[MARMAM] The ability of breath-hold diving vertebrates to vary heart rate

[Andreas Fahlman]

Dear MarMamers
For those interested in the heart rate response during diving, this article may 
be of interest and summarizes the current knowledge of the capacity of 
vertebrates to cognitively alter heart rate. The abstract and doi are included 
below and the link provides a number of free downloads. If you would like a pdf 
copy and cannot access it below, please send me an email.
Sincerely,
Andreas

Title: The role of cognition as a factor regulating the diving responses of 
animals, including humans

Authors: Fahlman, A., Burggren, W., Milsom, W.K.

Abstract: The dive response involves three main components - breath holding, 
reduced heart rate and increased peripheral vasoconstriction - and is 
ubiquitous during forced dives in air-breathing vertebrates; however, numerous 
studies in free-diving animals have shown that the heart rate response to 
diving varies considerably in a manner that suggests cognitive control. 
Furthermore, studies on free-diving animals and controlled experiments in 
trained animals both indicate that the dive response can be conditioned, such 
that the reduction in heart rate begins before submergence and the extent of 
the reduction is set early in the dive. In addition, numerous species also 
experience an increase in heart rate and blood flow during ascent at the end of 
a dive, a phenomenon commonly called 'ascent tachycardia'. Collectively, these 
data suggest that although the dive response is under autonomic control, many 
species can vary its magnitude depending on the length and type of the planned 
dive - an indication of a role for cognition in the overall physiological 
responses associated with diving. Here, we provide examples of the conditioned 
cardiac responses - including anticipatory changes in heart rate - in several 
diving species and propose potential underlying mechanisms. We also discuss how 
the anticipatory cardiovascular responses not only improve diving capacity, but 
also prevent diving-related problems, such as decompression sickness or 
barotrauma, through a mechanism described by the selective gas exchange 
hypothesis.

doi: https://doi.org/10.1242/jeb.246472

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[MARMAM] Baseline lung function values in healthy dolphins

[Andreas Fahlman]

Dear MarMamers
We would like to share our new open-access publication titled "Respiratory 
reference values for bottlenose dolphins (Tursiops spp.) and its importance for 
conservation" where we define baseline lung function variables in bottlenose 
dolphins and how these may be useful for conservation efforts on cetaceans.
The article is open access and can be found at the link below.
Sincerely,
Andreas

Title: Respiratory reference values for bottlenose dolphins (Tursiops spp.) and 
its importance for conservation
Authors: Cauture, F.,  Sweeney, J., Stone, R., Fahlman, A.
Journal: Marine Mammal Science:
doi: http://doi.org/10./mms.13151
Abstract: Respiratory disease is one of the main causes for morbidity and 
mortality in cetaceans, which highlights the importance of understanding normal 
lung function and how it may impede homeostasis, and diving capacity. In 
addition, the use of breathing frequency as a proxy for metabolic rate requires 
a better estimate of the normal range of tidal volume, respiratory flow, and 
breath durations. In the current study, we use data on clinically healthy 
bottlenose dolphins (Tursiops spp.) collected over a decade to define how lung 
function varies with body mass, age, and sex while in water or during voluntary 
beaching. The data show that tidal volume consistently varies with body mass 
both during spontaneous and forced breaths both in water and while beached. 
Both peak expiratory and inspiratory flow varies with body mass, but also in 
some circumstances with sex and age. Total and inspiratory breath durations 
only varied with body mass during forced breaths on land. Expired tidal volume 
varied with both body mass and either total or expiratory breath duration. 
These data provide baseline for respiratory function in healthy bottlenose 
dolphins and suggest that either total or expiratory breath duration provide a 
useful proxy for tidal volume.
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[MARMAM] The selective gas exchange hypothesis, a mechanism how cetaceans avoids the bends?!

[Andreas Fahlman]

Dear MarMamers
A new review on the cardiorespiratory physiology in cetaceans is published in 
Experimental Physiology and summarizes the current knowledge on 
cardiorespiratory physiology and how a combination of anatomy and physiology 
allows cetaceans to manage gases while diving. This mechanism, the selective 
gas exchange hypothesis, was proposed to explain how cetaceans avoid excessive 
uptake of N2 while also being able to exchange O2 and CO2 while diving. This 
article is open access and can be downloaded at: 
https://physoc.onlinelibrary.wiley.com/doi/10.1113/EP091095 (doi: 
10.1113/EP091095), and if you have any questions, please contact me at: 
gdrs...@gmail.com
Sincerely,
Andreas

Title: Cardiorespiratory adaptations in small cetaceans and marine mammals
Author: Fahlman, A.
Journal: Experimental Physiology
doi: 10.1113/EP091095
ABSTRACT
The dive response, or the “master switch of life”, is probably the most studied 
physiological trait in marine mammals and is generally thought to conserve the 
available O2 for the heart and brain. Although generally thought to be an 
autonomic reflex, several studies indicate that the cardiovascular changes 
during diving can also be conditioned. The respiratory adaptations, where the 
aquatic breathing pattern resemble intermittent breathing in land mammals, with 
expiratory flow exceeding 160 l · sec-1 has been measured in cetaceans, and 
where exposure to extreme pressures result in alveolar collapse (atelectasis) 
and recruitment upon ascent. Cardiorespiratory coupling, where breathing 
results in changes in heart rate, has been proposed to improve gas exchange. 
This cardiorespiratory coupling has also been reported in marine mammals, and 
in the bottlenose dolphin, where it alters both heart rate and stroke volume. 
When accounting for this respiratory dependence on cardiac function, several 
studies have reported an absence of a diving related bradycardia except during 
dives that exceed the duration that appears to be fuelled by aerobic 
metabolism. In this review, the attempt is made to summarize what is known 
about the respiratory physiology in marine mammals, with a special focus on 
cetaceans. The cardiorespiratory coupling is reviewed, and the selective gas 
exchange hypothesis is summarized, which provides a testable mechanism how 
breath-hold diving vertebrates may actively prevent uptake of N2 during routine 
dives and how stress results in failure of this mechanism which results in 
diving related gas emboli.
NEW FINDINGS:
1. What is the topic of this review?
This review summarizes the current knowledge of the respiratory physiology in 
small cetaceans and its influence of cardiac function.

2. What advances does it highlight?
The review presents the selective gas exchange hypothesis, which is a framework 
how marine mammals manage gases during diving and based upon the current 
understanding of cardiorespiratory coupling in breath-hold diving vertebrates.

KEYWORDS: diving physiology, marine mammal, cetacean, heart rate, perfusion
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[MARMAM] Resting/basal metabolic rate and lung function in the rough toothed dolphin

[Andreas Fahlman]

Dear MarMamers
We would like to share our new open-access publication that measured the 
resting/basal metabolism, the cost of digestion (heat increment of feeding), 
and lung function in the rough toothed dolphin. The details about the paper can 
be found below, and please send me an email if you have any questions or cannot 
get access to this open access paper..
Sincerely,
Andreas

Title: Resting metabolic rate and lung function in fasted and fed rough-toothed 
dolphins, Steno bredanensis
Authors: Andreas Fahlman, Kaylee Rhieu, Brie Alessi, Shelly Marquardt, Michelle 
B. Schisa, Guillermo J. Sanchez-Contreras, Josefin Larsson
Journal: Marine Mammal Science
doi: https://doi.org/10./mms.13068
Abstract: We measured resting metabolic rate (RMR), tidal volume (VT), 
breathing frequency (fR), respiratory flow, and end-expired gases in 
rough-toothed dolphins (Steno bredanensis) housed in managed care after an 
overnight fast and 1–2 hr following a meal. The measured average (± standard 
deviation) VT (4.0 ± 1.3 L) and fR (1.9 ± 1.0 breaths/min) were higher and 
lower, respectively, as compared with estimated values from both terrestrial 
and aquatic mammals, and the average VT was 43% of the estimated total lung 
capacity. The end-expired gas levels suggested that this species keep alveolar 
O2 (10.6% or 80 mmHg) and CO2 (7.6% or 57 mmHg), and likely arterial gas 
tensions, low and high, respectively, to maximize efficiency of gas exchange. 
We show that following an overnight fast, the RMR (566 ± 158 ml O2/min) was 1.8 
times the estimated value predicted by Kleiber for terrestrial mammals of the 
same size. We also show that between 1 and 2 hr after ingestion of a meal, the 
metabolic rate increases an average of 29% (709 ± 126 ml O2/min). Both body 
mass (Mb) and fR significantly altered the measured RMR and we propose that 
both these variables should be measured when estimating energy use in cetaceans.
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[MARMAM] Cardiorespiratory function in the bottlenose dolphins

[Andreas Fahlman]

Dear MarMamers
We would like to share our new open-access publication that investigated how 
breathing is affecting heart rate. The details about the paper can be found 
below, and please send me an email if you have any questions.
Sincerely,
Andreas

Title Cardiorespiratory coupling in the bottlenose dolphin (Tursiops truncatus)
Authors: A. Fahlman, J. C. Mcknight, A. M. Blawas, N. West, A. G. Torrente, K. 
Aoki
Journal: Frontiers Physiology
doi: https://doi.org/10.3389/fphys.2023.1234432
Abstract:
Introduction: The bottlenose dolphin (Tursiops truncatus) is an intermittent 
breather, where the breath begins with an exhalation followed by inhalation and 
an extended inter-breath interval ranging from 10 to 40 s. Breathing has been 
shown to alter both the instantaneous heart rate (ifH) and stroke volume (iSV) 
in the bottlenose dolphin, with a transitory ventilatory tachycardia following 
the breath, and an exponential decrease to a stable ifH around 40 beats • min−1 
during the inter-breath period. As the total breath duration in the dolphin is 
around 1 s, it is not possible to assess the contribution of exhalation and 
inhalation to these changes in cardiac function during normal breathing.
Methods: In the current study, we evaluated the ifH response by separating 
expiration and inspiration of a breath, which allowed us to distinguish their 
respective contribution to the changes in ifH. We studied 3 individual male 
bottlenose dolphins trained to hold their breath between the different 
respiratory phases (expiration and inhalation).
Results: Our data show that inspiration causes an increase in ifH, while 
expiration appears to result in a decrease in ifH.
Discussion: These data provide improved understanding of the cardiorespiratory 
coupling in dolphins, and show how both exhalation and inhalation alters ifH.
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[MARMAM] Shining light on dolphin physiology

[Andreas Fahlman]

Dear MarMamers
We would like to share our new open-access publication that investigated the 
use of Near Infrared Spectroscopy as a non-invasive tool to study physiology in 
the bottlenose dolphin. We report preliminary data which indicate that this 
technology allows us to measure blood flow and tissue and blood oxygenation in 
this dolphins. The details about the paper can be found below, and please send 
me or Alex Ruesch (arue...@andrew.cmu.edu) an email if you have any questions.
Sincerely,
Andreas

Title: Evaluating feasibility of functional near-infrared spectroscopy in 
dolphins
Authors: Ruesch, A., Acharya, D., Bulger, E., Cao, J., McKnight, J. C., Manley, 
M., Fahlman, A., Shinn-Cunningham, B. G. and Kainerstorfer, J. M.
Journal: Journal of Biomedical Optics
doi: 10.1117/1.JBO.28.7.075001
Abstract: Significance: Using functional near-infrared spectroscopy (fNIRS) in 
bottlenose dolphins (Tursiops truncatus) could help to understand how 
echolocating animals perceive their environment and how they focus on specific 
auditory objects, such as fish, in noisy marine settings.
Aim: To test the feasibility of near-infrared spectroscopy (NIRS) in 
medium-sized marine mammals, such as dolphins, we modeled the light propagation 
with computational tools to determine the wavelengths, optode locations, and 
separation distances that maximize sensitivity to brain tissue.
Approach: Using frequency-domain NIRS, we measured the absorption and reduced 
scattering coefficient of dolphin sculp. We assigned muscle, bone, and brain 
optical properties from the literature and modeled light propagation in a 
spatially accurate and biologically relevant model of a dolphin head, using 
finite-element modeling. We assessed tissue sensitivities for a range of 
wavelengths (600 to 1700 nm), source-detector distances (50 to 120 mm), and 
animal sizes (juvenile model 25% smaller than adult).
Results: We found that the wavelengths most suitable for imaging the brain fell 
into two ranges: 700 to 900 nm and 1100 to 1150 nm. The optimal location for 
brain sensing positioned the center point between source and detector 30 to 50 
mm caudal of the blowhole and at an angle 45 deg to 90 deg lateral off the 
midsagittal plane. Brain tissue sensitivity comparable to human measurements 
appears achievable only for smaller animals, such as juvenile bottlenose 
dolphins or smaller species of cetaceans, such as porpoises, or with 
source-detector separations ≫100 mm in adult dolphins.
Conclusions: Brain measurements in juvenile or subadult dolphins, or smaller 
dolphin species, may be possible using specialized fNIRS devices that support 
optode separations of >100 mm. We speculate that many measurement repetitions 
will be required to overcome hemodynamic signals originating predominantly from 
the muscle layer above the skull. NIRS measurements of muscle tissue are 
feasible today with source-detector separations of 50 mm, or even less..

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[MARMAM] Extreme diving by Bottlenose dolphins

[Andreas Fahlman]

Dear MarMamers
We would like to share our new open-access publication that investigated the 
dive behavior of bottlenose dolphins in Bermuda. We report the deepest dive 
recorded for a bottlenose dolphin of 1000 meter. The details about the paper 
can be found below, and please send me an email if you have any questions.
Sincerely,
Andreas
Title: Deep diving by offshore bottlenose dolphins (Tursiops spp.)
Authors: Fahlman, A., Tyson Moore, R. B., Stone, R., Sweeney, J., Faulkner 
Trainor, R., Barleycorn, A.A., McHugh, K., Allen, J.B., Wells, R.S.
Journal: Marine Mammal Science:
doi: https://doi.org/10./mms.13045
Abstract: We used satellite-linked tags to evaluate dive behavior in offshore 
bottlenose dolphins (Tursiops spp.) near the island of Bermuda. The data 
provide evidence that bottlenose dolphins commonly perform both long (>272 s) 
and deep (>199 m) dives, with the deepest and longest dives being to 1,000 m 
and 826 s (13.8 min), respectively. The data show a relationship between dive 
duration and dive depth for dives longer than about 272 s. There was a diurnal 
pattern to dive behavior, with most dives deeper than 50 m being performed at 
night; deep diving began at sunset and varied throughout the night. We used the 
cumulative frequency of dive duration to estimate a behavioral aerobic dive 
limit (bADL) of around 560-666 s (9.3-11.1 min) in adult dolphins in this 
population. Dives exceeding the bADL spent significantly longer time in the 
upper-most 50 m following a dive as compared with dives less than the bADL. We 
conclude that the offshore ecotype off Bermuda, unlike the shallow-diving 
near-shore bottlenose dolphin, is a deep diving ecotype, and may provide a 
useful animal model to study extreme diving behavior and adaptations.
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[MARMAM] New publication on energy flow in aquatic and terrestrial mammals

[Andreas Fahlman]

Dear colleagues,

On behalf of my co-authors, I am happy to announce the publication of our new 
paper in Physiological Reports

Title: Allometric scaling of metabolic rate and cardiorespiratory variables in 
aquatic and terrestrial mammals

Authors: Rebecca S. He, Stacy De Ruiter, Tristan Westover, Jason A. Somarelli, 
Ashley M. Blawas, Divya L. Dayanidhi, Ana Singh, Benjamin Steves, Samantha 
Driesinga, Lewis G. Halsey, Andreas Fahlman

Journal: Physiological Reports

Full view access to the article can be found here:
https://physoc.onlinelibrary.wiley.com/doi/abs/10.14814/phy2.15698

Abstract:
While basal metabolic rate (BMR) scales proportionally with body mass (Mb), it 
remains unclear whether the relationship differs between mammals from aquatic 
and terrestrial habitats. We hypothesized that differences in BMR allometry 
would be reflected in similar differences in scaling of O2 delivery pathways 
through the cardiorespiratory system. We performed a comparative analysis of 
BMR across 63 mammalian species (20 aquatic, 43 terrestrial) with a Mb range 
from 10 kg to 5318 kg. Our results revealed elevated BMRs in small (>10 kg and 
<100 kg) aquatic mammals compared to small terrestrial mammals. The results 
demonstrated that minute ventilation, that is, tidal volume (VT)·breathing 
frequency (fR), as well as cardiac output, that is, stroke volume·heart rate, 
do not differ between the two habitats. We found that the “aquatic breathing 
strategy”, characterized by higher VT and lower fR resulting in a more 
effective gas exchange, and by elevated blood hemoglobin concentrations 
resulting in a higher volume of O2 for the same volume of blood, supported 
elevated metabolic requirements in aquatic mammals. The results from this study 
provide a possible explanation of how differences in gas exchange may serve 
energy demands in aquatic versus terrestrial mammals.

Feel free to contact me with any questions.

Andreas

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[MARMAM] Publication on diving metabolism

[Andreas Fahlman]

Dear MARMAMers,

My co-authors and I are pleased to share this new open-access publication:
Fahlman A, Allen AS, Blawas A, Sweeney J, Stone R, Trainor R, Jensen FH, McHugh 
K, Allen JB, Barleycorn AA & Wells RS (2023). Surface and diving metabolic 
rates, and dynamic aerobic dive limits (dADL) in near- and off-shore bottlenose 
dolphins, Tursiops spp., indicate that deep diving is energetically cheap. 
Marine Mammal Science, 1-18.

Abstract:
High-resolution dive depth and acceleration recordings from nearshore (Sarasota 
Bay, dive depth < 30 m), and offshore (Bermuda) bottlenose dolphins (Tursiops 
spp.) were used to estimate the diving metabolic rate (DMR) and the locomotor 
metabolic rate (LMR, L O2/min) during three phases of diving (descent, bottom, 
and ascent). For shallow dives (depth ≤ 30 m), we found no differences between 
the two ecotypes in the LMR during diving, nor during the postdive shallow 
interval between dives. For intermediate (30 m < depth ≤ 100 m) and deep dives 
(depth > 100 m), the LMR was significantly higher during ascent than during 
descent and the bottom phase by 59% and 9%, respectively. In addition, the rate 
of change in depth during descent and ascent (meters/second) increased with 
maximal dive depth. The dynamic aerobic dive limit (dADL) was calculated from 
the estimated DMR and the estimated predive O2 stores. For the Bermuda 
dolphins, the dADL decreased with dive depth, and was 18.7, 15.4, and 11.1 min 
for shallow, intermediate, and deep dives, respectively. These results provide 
a useful approach to understand the complex nature of physiological 
interactions between aerobic metabolism, energy use, and diving capacity.

Publication available open access here: https://doi.org/10./mms.13023

If you have any questions or need a pdf copy of the paper, you can reach me at: 
afahl...@whoi.edu



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[MARMAM] Respiratory function in dolphins on land

[Andreas Fahlman]

Dear MarMamers
We would like to share our new publication investigating the respiratory 
effects of beaching in healthy bottlenose dolphins. The citation and abstract 
are pasted below. For pdf requests, please send an email to: afahl...@whoi.ed

Sincerely,
Andreas and co-authors

Citation: Fahlman, A., Brodsky, M., Rocho-Levine, J., Garcia-Parraga, D., 
Ivančić, M., Camarena, C., Ibarra, L., and Rocabert, J. (2021). Respiratory 
changes in stranded bottlenose dolphins (Tursiops truncatus) Journal of Zoo and 
Wildlife Medicine 52, 49-56, 48.https://doi.org/10.1638/2020-0033

Abstract: Lung function (breath duration, respiratory flow [], and tidal volume 
[VT]), and end-expiratory O2 were measured in 19 adult bottlenose dolphins 
(Tursiops spp.) while at rest in water or beached for up to 10 min. The results 
show that inspiratory VT, expiratory VT, or inspiratory did not differ on land 
or in water. The average expiratory for all dolphins on land decreased by 16%, 
and the expiratory and total breath durations increased by 5% and 4%, 
respectively, compared with in water. There were temporal changes observed 
during beaching, where expired and inspired VT and inspired decreased by 13%, 
16%, and 9%, respectively, after 10 min on land. These data suggest that 
dolphins compensate for the effect of gravity by adjusting respiration to 
maintain alveolar ventilation and gas exchange, but during extended durations, 
the increased work of breathing may impede ventilation and gas exchange. 
Continuous monitoring of lung function and gas exchange may help prevent 
long-term damage during out-of-water medical procedures, optimize animal 
transport conditions, and improve survival during stranding events.

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Re: [MARMAM] How do marine mammals avoid the bends during diving?

[Andreas Fahlman]

Dear All
My apologies and the link to the paper below was to another article and for 
anyone interested in the review, it can be found here:

https://www.frontiersin.org/articles/10.3389/fmars.2021.598633/full

Again, sincere apologies for the hassle.

Best
Andreas 

> On 6 Feb 2021, at 19:31, Andreas Fahlman  wrote:
> 
> Dear MarMamers
> My coauthors and I would like to share our new open access review on “How Do 
> Marine Mammals Manage and Usually Avoid Gas Emboli Formation and Gas Embolic 
> Pathology? Critical Clues From Studies of Wild Dolphins” 
> (https://www.frontiersin.org/article/10.3389/fmars.2021.598633), which is a 
> part of a collection of papers that celebrates "The Dolphins of Sarasota Bay: 
> Lessons from 50 years of Research and Conservation" 
> (https://www.frontiersin.org/research-topics/12832).
> 
> In this review, we have tried to summarize decompression theory based on 
> studies on humans and land mammals that have allowed us to understand the 
> physiological processes that may result in Gas Embolic Pathology (GEP) in 
> marine mammals (and sea turtles). We then review the studies over the last 15 
> years that have investigated the the potential mechanism that result in GEP 
> in during unusual events such as sonar exposure, and how this research has 
> resulted in the Selective gas Exchange which explains how marine mammals can 
> selective exchange oxygen and carbon dioxide without exchange of nitrogen and 
> thereby maximize aerobic dive duration and also minimize the risk of the 
> bends (see below for short video explaining this hypothesis).
>  
> If you have any questions, please do not hesitate to get in contact: 
> afahl...@whoi.edu
> 
> Title: How Do Marine Mammals Manage and Usually Avoid Gas Emboli Formation 
> and Gas Embolic Pathology? Critical Clues From Studies of Wild Dolphins
> 
> Authors: Fahlman,A., Moore, M.J., Wells, R.S.
> 
> DOI: 10.3389/fmars.2021.598633
> 
> URL: https://www.frontiersin.org/article/10.3389/fmars.2021.598633
> 
> Abstract: Decompression theory has been mainly based on studies on 
> terrestrial mammals, and may not translate well to marine mammals. However, 
> evidence that marine mammals experience gas bubbles during diving is growing, 
> causing concern that these bubbles may cause gas emboli pathology (GEP) under 
> unusual circumstances. Marine mammal management, and usual avoidance, of gas 
> emboli and GEP, or the bends, became a topic of intense scientific interest 
> after sonar-exposed, mass-stranded deep-diving whales were observed with gas 
> bubbles. Theoretical models, based on our current understanding of diving 
> physiology in cetaceans, predict that the tissue and blood N2 levels in the 
> bottlenose dolphin (Tursiops truncatus) are at levels that would result in 
> severe DCS symptoms in similar sized terrestrial mammals. However, the 
> dolphins appear to have physiological or behavioral mechanisms to avoid 
> excessive blood N2 levels, or may be more resistant to circulating bubbles 
> through immunological/biochemical adaptations. Studies on behavior, anatomy 
> and physiology of marine mammals have enhanced our understanding of the 
> mechanisms that are thought to prevent excessive uptake of N2. This has led 
> to generation of a new hypothesis, the selective gas exchange hypothesis, as 
> to how stress-induced behavioral change may cause failure of the normal 
> physiology, which results in excessive uptake of N2, and in extreme cases may 
> cause formation of symptomatic gas emboli. Studies on cardiorespiratory 
> function have been integral to the development of this hypothesis, with work 
> initially being conducted on excised tissues and cadavers, followed by 
> studies on anesthetized animals or trained animals under human care, 
> participating voluntarily. These studies then enabled research on 
> free-ranging common bottlenose dolphins in Sarasota Bay, FL, and off Bermuda, 
> and have included work on the metabolic and cardiorespiratory physiology of 
> both shallow- and deep-diving dolphins and have been integral to better 
> understand how cetaceans can dive to extreme depths, for long durations.
> Explanation of the Selective Gas Exchange hypothesis:  
> https://www.youtube.com/watch?v=sfBOpUuJv1c
> 
> 
> 
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[MARMAM] How do marine mammals avoid the bends during diving?

[Andreas Fahlman]

Dear MarMamers
My coauthors and I would like to share our new open access review on “How Do 
Marine Mammals Manage and Usually Avoid Gas Emboli Formation and Gas Embolic 
Pathology? Critical Clues From Studies of Wild Dolphins” 
(https://www.frontiersin.org/article/10.3389/fmars.2021.598633 
), 
which is a part of a collection of papers that celebrates "The Dolphins of 
Sarasota Bay: Lessons from 50 years of Research and Conservation" 
(https://www.frontiersin.org/research-topics/12832).

In this review, we have tried to summarize decompression theory based on 
studies on humans and land mammals that have allowed us to understand the 
physiological processes that may result in Gas Embolic Pathology (GEP) in 
marine mammals (and sea turtles). We then review the studies over the last 15 
years that have investigated the the potential mechanism that result in GEP in 
during unusual events such as sonar exposure, and how this research has 
resulted in the Selective gas Exchange which explains how marine mammals can 
selective exchange oxygen and carbon dioxide without exchange of nitrogen and 
thereby maximize aerobic dive duration and also minimize the risk of the bends 
(see below for short video explaining this hypothesis).
 
If you have any questions, please do not hesitate to get in contact: 
afahl...@whoi.edu 

Title: How Do Marine Mammals Manage and Usually Avoid Gas Emboli Formation and 
Gas Embolic Pathology? Critical Clues From Studies of Wild Dolphins

Authors: Fahlman,A., Moore, M.J., Wells, R.S.

DOI: 10.3389/fmars.2021.598633 


URL: https://www.frontiersin.org/article/10.3389/fmars.2021.598633 


Abstract: Decompression theory has been mainly based on studies on terrestrial 
mammals, and may not translate well to marine mammals. However, evidence that 
marine mammals experience gas bubbles during diving is growing, causing concern 
that these bubbles may cause gas emboli pathology (GEP) under unusual 
circumstances. Marine mammal management, and usual avoidance, of gas emboli and 
GEP, or the bends, became a topic of intense scientific interest after 
sonar-exposed, mass-stranded deep-diving whales were observed with gas bubbles. 
Theoretical models, based on our current understanding of diving physiology in 
cetaceans, predict that the tissue and blood N2 levels in the bottlenose 
dolphin (Tursiops truncatus) are at levels that would result in severe DCS 
symptoms in similar sized terrestrial mammals. However, the dolphins appear to 
have physiological or behavioral mechanisms to avoid excessive blood N2 levels, 
or may be more resistant to circulating bubbles through 
immunological/biochemical adaptations. Studies on behavior, anatomy and 
physiology of marine mammals have enhanced our understanding of the mechanisms 
that are thought to prevent excessive uptake of N2. This has led to generation 
of a new hypothesis, the selective gas exchange hypothesis, as to how 
stress-induced behavioral change may cause failure of the normal physiology, 
which results in excessive uptake of N2, and in extreme cases may cause 
formation of symptomatic gas emboli. Studies on cardiorespiratory function have 
been integral to the development of this hypothesis, with work initially being 
conducted on excised tissues and cadavers, followed by studies on anesthetized 
animals or trained animals under human care, participating voluntarily. These 
studies then enabled research on free-ranging common bottlenose dolphins in 
Sarasota Bay, FL, and off Bermuda, and have included work on the metabolic and 
cardiorespiratory physiology of both shallow- and deep-diving dolphins and have 
been integral to better understand how cetaceans can dive to extreme depths, 
for long durations.
Explanation of the Selective Gas Exchange hypothesis:  
https://www.youtube.com/watch?v=sfBOpUuJv1c 


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[MARMAM] New publication: Can dolphins decide to reduce their heart rate?

[Andreas Fahlman]

Dear MarMamers
My coauthors and I would like to share our new publication on conditioned heart 
rate responses in dolphins 
(https://www.frontiersin.org/articles/10.3389/fphys.2020.604018/abstract). In 
this study we show that the change in heart rate during diving varies depending 
on anticipation. This suggest that dolphins conditionally reduce their heart 
rate, and these results provide further evidence for the Selective Gas Exchange 
hypothesis (https://royalsocietypublishing.org/doi/full/10.1098/rspb.2018.0482) 
that explains how marine mammals can selective exchange oxygen and carbon 
dioxide without exchange of nitrogen and thereby maximize aerobic dive duration 
and also minimize the risk of the bends (see below for short video explaining 
this hypothesis).

For more information, the title and abstract is below and also a link to the 
open access article. In addition, we have also included a video abstract of the 
paper, and also a link to an educational video explaining the Selective Gas 
Exchange hypothesis.

If you have any questions, please do not hesitate to get in contact: 
afahl...@whoi.edu


Title: Conditioned variation in heart rate during static breath-holds in the 
bottlenose dolphin (Tursiops truncatus)

Authors: Fahlman,A., Cozzi, B.,  Manley, M., Jabas, S.,  Malik, M., Blawas A., 
and Janik, V.M..

DOI: 10.3389/fphys.2020.604018

URL: https://www.frontiersin.org/articles/10.3389/fphys.2020.604018/abstract

Abstract: Previous reports suggested the existence of direct somatic motor 
control over heartrate (fH) responses during diving in some marine mammals, as 
the result of a cognitive and/or learning process rather than being a reflexive 
response. This would be beneficial for O2 storage management, but would also 
allow ventilation-perfusion matching for selective gas exchange, where O2 and 
CO2 can be exchanged with minimal exchange of N2. Such a mechanism explains how 
air breathing marine vertebrates avoid diving related gas bubble formation 
during repeated dives, and how stress could interrupt this mechanism and cause 
excessive N2 exchange. To investigate the conditioned response, we measured the 
fH-response before and during static breath-holds in three bottlenose dolphins 
(Tursiops truncatus) when shown a visual symbol to perform either a long (LONG) 
or short (SHORT) breath-hold, or during a spontaneous breath-hold without a 
symbol (NS). The average fH (ifHstart), and the rat!
 e of change in fH (difH/dt) during the first 20 s of the breath-hold differed 
between breath-hold types. In addition, the minimum instantaneous fH (ifHmin), 
and the average instantaneous fH during the last 10 s (ifHend) also differed 
between breath-hold types. The difH/dt was greater, and the ifHstart, ifHmin, 
and ifHend were lower during a LONG as compared with either a SHORT, or an NS 
breath-hold (P < 0.05). Even though the NS breath-hold dives were longer in 
duration as compared with SHORT breath-hold dives, the difH/dt was greater and 
the ifHstart, ifHmin, and ifHend were lower during the latter (P < 0.05). In 
addition, when the dolphin determined the breath-hold duration (NS), the fH was 
more variable within and between individuals and trials, suggesting a 
conditioned capacity to adjust the fHresponse. These results suggest that 
dolphins have the capacity to selectively alter the fH-response during diving 
and provide evidence for significant cardiovascular plasticity
in dolphins.

Video summary: https://www.youtube.com/watch?v=666zieqGv0A

Explanation of the Selective Gas Exchange hypothesis:  
https://www.youtube.com/watch?v=sfBOpUuJv1c

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[MARMAM] Heart function in cetaceans

[Andreas Fahlman]

Dear MARMAM community,

We would like to share our new publication on cardiac function and 
cardiorespiratory coupling in cetaceans. In this study, the function of the 
heart was investigated in the bottlenose dolphin, the beluga, the killer whale, 
the false killer whale, and the pilot whale. The results showed that cetaceans 
have large variation in heart rate directly after a breath, and when compared 
with land mammals, the relationship between breathing frequency and heart rate 
is very different. We propose that these differences may indicate a mechanism 
that helps improve gas exchange during a surface interval.

Fahlman, A., Miedler, S., Marti-Bonmati, L., Ferrero Fernandez, D., Muñoz 
Caballero, P., Arenarez, J., Rocho-Levine, J., Robeck, T., and Blawas, A.M. 
(2020). Cardiorespiratory coupling in cetaceans; a physiological strategy to 
improve gas exchange? Journal of Experimental Biology 223, jeb226365.

Video abstract: https://www.youtube.com/watch?v=WxqKniwIVf4 


Abstract: In the current study we used transthoracic echocardiography to 
measure stroke volume (SV), heart rate ( fH) and cardiac output (CO) in adult 
bottlenose dolphins (Tursiops truncatus), a male beluga whale calf 
[Delphinapterus leucas, body mass (Mb) range: 151–175 kg] and an adult female 
false killer whale (Pseudorca crassidens, estimated Mb: 500–550 kg) housed in 
managed care.Wealso recorded continuous electrocardiogram (ECG) in the beluga 
whale, bottlenose dolphin, false killer whale, killer whale (Orcinus orca) and 
pilot whale (Globicephala macrorhynchus) to evaluate cardiorespiratory coupling 
while breathing spontaneously under voluntary control. The results show that 
cetaceans have a strong respiratory sinus arrythmia (RSA), during which both fH 
and SV vary within the interbreath interval, making average values dependent on 
the breathing frequency ( fR). The RSA-corrected fH was lower for all cetaceans 
compared with that of similarly sized terrestrial mammals breathing 
continuously. As compared with terrestrial mammals, the RSA-corrected SV and CO 
were either lower or the same for the dolphin and false killer whale, while 
both were elevated in the beluga whale. When plotting fR against fH for an 
inactive mammal, cetaceans had a greater cardiac response to changes in fR as 
compared with terrestrial mammals.We propose that these data indicate an 
important coupling between respiration and cardiac function that enhances gas 
exchange, and that this RSA is important to maximize gas exchange during 
surface intervals, similar to that reported in the elephant seal.

The journal provides a couple of free downloads that can be found here: 
https://jeb.biologists.org/content/jexbio/223/17/jeb226365.full.pdf?ijkey=zKzvXDpWjAFqTvV&keytype=finite
 

Or else please send me an email if you would like a pdf copy at: 
afahl...@whoi.edu 

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[MARMAM] Blood and tissue gas solubility alters lung volume during diving

[Andreas Fahlman]

Dear All
We are happy to share our new paper that details how differences in blood and 
tissue gas solubility of oxygen, carbon dioxide and nitrogen results in changes 
in mass-balance and ung volume during diving. The reference, url and abstract 
are below and anyone wanting a pdf copy of the article can send an email to: 
afahl...@whoi.edu <mailto:afahl...@whoi.edu>
Thank you
Andreas

Reference: Fahlman, A., Sato, K., and Miller, P. (2020). Improving estimates of 
diving lung volume in air-breathing marine vertebrates. The Journal of 
Experimental Biology 223, jeb216846. DOI: 10.1242/jeb.216846
URL: https://jeb.biologists.org/content/223/12/jeb216846 
<https://jeb.biologists.org/content/223/12/jeb216846> 

Abstract:
The air volume in the respiratory system of marine tetrapods provides a store 
of O2 to fuel aerobic metabolism during dives; however, it canalso be a 
liability, as the associated N2 can increase the risk of decompression 
sickness. In order to more fully understand the physiological limitations of 
different air-breathing marine vertebrates, it is therefore important to be 
able to accurately estimate the air volume in the respiratory system during 
diving. One method that has been used to do so is to calculate the air volume 
from glide phases – periods of movement during which no thrust is produced by 
the animal – which many species conduct during ascent periods, when gases are 
expanding owing to decreasing hydrostatic pressure. This method assumes that 
there is conservation of mass in the respiratory system, with volume changes 
only driven by pressure. In this Commentary, we use previously published data 
to argue that both the respiratory quotient and differences in tissue and blood 
gas solubility potentially alter the mass balance in the respiratory system 
throughout a dive. Therefore, near the end of a dive, the measured volume of 
gas at a given pressure may be 12–50% less than from the start of the dive; the 
actual difference will depend on the length of the dive, the cardiac output, 
the pulmonary shunt and the metabolic rate. Novel methods and improved 
understanding of diving physiology will be required to verify the size of the 
effects described here and to more accurately estimate the volume of gas 
inhaled at the start of a dive.

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[MARMAM] Online course @ Duke University: Building a Database for Marine Mammal Molecular Genetics, Anatomy, and Physiology.

[Andreas Fahlman]

Building a Database for Marine Mammal Molecular Genetics, Anatomy, and 
Physiology. Online course @ Duke University

Decades of research in molecular biology and physiology has produced a treasure 
trove of data that illuminate how different cell types and organ systems 
respond to environmental stimuli across marine mammal species. Yet, despite 
this wealth of knowledge, access to this incredible resource is hampered by the 
lack of a central database in which to access and integrate these data sets. In 
this problem- and team-based on-line course, we will work with students as a 
virtual team to create and publish a comparative molecular, anatomical and 
physiological data base. The students, Teaching Assistant (TA), and instructors 
(the team) will work together to search for published peer reviewed articles 
for marine mammals. The information will be extracted and inserted into a 
central place for searching. We are specifically interested in adaptations from 
a range of marine species with a focus on integrating marine mammal physiologic 
and molecular systems and environmental adaptations. 
 
The class will produce a deliverable in the form of the launch of a web-based 
platform with a searchable body with different organs and systems in one marine 
mammal species that includes details about which of these are absent or 
anatomically different in other species. Another output would be updated 
information on allometric scaling relationships that include more species and 
that are phylogenetically corrected. Prerequisites: college introductory 
biology, introductory chemistry, or consent of the instructor.
 
Instructors:
·Andreas Fahlman (afahl...@duke.edu <mailto:afahl...@whoi.edu>)
·Jason Somarelli (jason.somare...@duke.edu 
<mailto:jason.somare...@duke.edu>)
 
Undergraduate Registration: ENV 390-02
Tuition: $2,500+fees
 
Dates: July 7 - July 30, 2020, Weekdays 9-12 EST

To apply: Visit Duke’s Summer Session website: 
https://summersession.duke.edu/visiting-college-students 
<https://summersession.duke.edu/visiting-college-students> and complete the 
online application:https://duke.qualtrics.com/jfe/form/SV_22XiGjJTUGVB7lb 
<https://duke.qualtrics.com/jfe/form/SV_22XiGjJTUGVB7lb>
 
Tuition and fees can be found here: 
https://summersession.duke.edu/visiting-college-students/u-s-students/tuition-aid
 
<https://summersession.duke.edu/visiting-college-students/u-s-students/tuition-aid>

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Re: [MARMAM] Comparative respiratory physiology in cetaceans

[Andreas Fahlman]

Dear All
Apologies for the double post, but for some reason the DOI is correct but the 
link directs you to another article and for anyone interest use either of these:
https://www.frontiersin.org/articles/10.3389/fphys.2020.00142/full
or 
 https://doi.org/10.3389/fphys.2020.00142

Sincerely,
Andreas

> On 3Mar, 2020, at 07:21, Andreas Fahlman  wrote:
> 
> Dear All
> We are happy to share our new publication looking at lung function in a 
> number of cetaceans. We investigated lung function in 2 false killer whales 
> and a juvenile beluga and compared these against previously published data. 
> These data provide comparative estimates for tidal volume, respiratory 
> frequency, and flow in a range of cetacean species. These data show that 
> tidal volume in cetaceans is greater while breathing frequency is lower as 
> compared with terrestrial mammals. However, tidal volume is only about 30% of 
> total lung capacity, much smaller than most past studies have assumed.
> 
> Abstract: In the current study we used breath-by-breath respirometry to 
> evaluate respiratory physiology under voluntary control in a male beluga calf 
> (Delphinapterus leucas, body mass range [Mb]: 151-175 kg), an adult female 
> (estimated Mb = 500-550kg) and a juvenile male (Mb = 279kg) false killer 
> whale (Pseudorca crassidens) housed in managed care. Our results suggest that 
> the measured breathing frequency (fR) is lower, while tidal volume (VT) is 
> significantly greater as compared with allometric predictions from 
> terrestrial mammals. Including previously published data from adult 
> bottlenose dolphin (Tursiops truncatus) beluga, harbour porpoise (Phocoena 
> phocoena), killer whale (Orcinus orca), pilot (Globicephala scammoni), and 
> gray whale (Eschrichtius robustus) show that the allometric mass-exponents 
> for VT and fR are similar to that for terrestrial mammals (VT: 1.00, fR: 
> -0.20). In addition, our results suggest an allometric relationship for 
> respiratory flow, with a mass-exponent between 0.63-0.70, and where the 
> expiratory flow was an average 30% higher as compared with inspiratory flow. 
> These data provide enhanced understanding of the respiratory physiology of 
> cetaceans and are useful to provide proxies of lung function to better 
> understand lung health or physiological limitations.
> 
> Reference: Fahlman, A., Borque-Espinosa, A., Facchin, F., Ferrero Fernandez, 
> D., Muñoz Caballero, P., Haulena, M Rocho-Levine, J. Comparative respiratory 
> physiology in cetaceans. Frontiers Physiology. 11(142): 2020. 
> https://doi.org/10.3389/fphys.2020.00142 
> <https://www.aquaticmammalsjournal.org/index.php?option=com_content&view=article&id=1978&catid=185&Itemid=326>
> 
> The article is open access and can be downloaded at: 
> https://doi.org/10.3389/fphys.2020.00142 
> <https://www.aquaticmammalsjournal.org/index.php?option=com_content&view=article&id=1978&catid=185&Itemid=326>
> Or a pdf can be requested through afahl...@whoi.edu 
> <mailto:afahl...@whoi.edu>___
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[MARMAM] Comparative respiratory physiology in cetaceans

[Andreas Fahlman]

Dear All
We are happy to share our new publication looking at lung function in a number 
of cetaceans. We investigated lung function in 2 false killer whales and a 
juvenile beluga and compared these against previously published data. These 
data provide comparative estimates for tidal volume, respiratory frequency, and 
flow in a range of cetacean species. These data show that tidal volume in 
cetaceans is greater while breathing frequency is lower as compared with 
terrestrial mammals. However, tidal volume is only about 30% of total lung 
capacity, much smaller than most past studies have assumed.

Abstract: In the current study we used breath-by-breath respirometry to 
evaluate respiratory physiology under voluntary control in a male beluga calf 
(Delphinapterus leucas, body mass range [Mb]: 151-175 kg), an adult female 
(estimated Mb = 500-550kg) and a juvenile male (Mb = 279kg) false killer whale 
(Pseudorca crassidens) housed in managed care. Our results suggest that the 
measured breathing frequency (fR) is lower, while tidal volume (VT) is 
significantly greater as compared with allometric predictions from terrestrial 
mammals. Including previously published data from adult bottlenose dolphin 
(Tursiops truncatus) beluga, harbour porpoise (Phocoena phocoena), killer whale 
(Orcinus orca), pilot (Globicephala scammoni), and gray whale (Eschrichtius 
robustus) show that the allometric mass-exponents for VT and fR are similar to 
that for terrestrial mammals (VT: 1.00, fR: -0.20). In addition, our results 
suggest an allometric relationship for respiratory flow, with a mass-exponent 
between 0.63-0.70, and where the expiratory flow was an average 30% higher as 
compared with inspiratory flow. These data provide enhanced understanding of 
the respiratory physiology of cetaceans and are useful to provide proxies of 
lung function to better understand lung health or physiological limitations.

Reference: Fahlman, A., Borque-Espinosa, A., Facchin, F., Ferrero Fernandez, 
D., Muñoz Caballero, P., Haulena, M Rocho-Levine, J. Comparative respiratory 
physiology in cetaceans. Frontiers Physiology. 11(142): 2020. 
https://doi.org/10.3389/fphys.2020.00142 


The article is open access and can be downloaded at: 
https://doi.org/10.3389/fphys.2020.00142 

Or a pdf can be requested through afahl...@whoi.edu 

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[MARMAM] Spirometry in dolphins, a conservation tool to help wild cetaceans

[Andreas Fahlman]

Dear All
We are happy to share our new publication looking at lung function/spirometry 
as a diagnostic tool to assess lung health in bottlenose dolphins. We evaluated 
lung health in 3 bottlenose dolphins under human care to assess whether 
pulmonary function testing (or spirometry) provide diagnostic information about 
respiratory health. In human medicine, respiratory health is evaluated through 
measurement of respiratory flow from maximal respiratory manoeuvres. In this 
study, we collected data from trained maximal respiratory efforts in water and 
from spontaneous breaths while beached. We evaluated how the flow-volume 
relationship and two indices of respiratory capacity changed for the animals 
when diagnosed with pulmonary disease, and during treatment and recovery. Our 
study suggest that pirometry in marine mammals could provide a simple, portable 
and non-invasive diagnostic tool to help assess respiratory health in dolphins 
under human care, and improve  conservation efforts while assessing health 
status in wild stranded animals..

Abstract: Pulmonary function testing was performed in 3 dolphins under managed 
care (1 female and 2 males) during a 2-year period to assess whether these data 
provide diagnostic information about respiratory health. Pulmonary radiographs 
and standard clinical testing were used to evaluate the pulmonary health of 
each dolphin. The female dolphin had evidence of chronic pulmonary fibrosis 
(F1), and one male developed pneumonia during the study (M2). Pulmonary 
function data were collected from maximal respiratory efforts in water and from 
spontaneous breaths while beached. From these data, the flow-volume 
relationship, the flow measured between 25% and 75% of the expired vital 
capacity (FEF25%-75%), and the percent of the vital capacity (VC) at the peak 
expiratory flow (%VCPEF), were evaluated and compared with the diagnostic 
assessment. For maximal respiratory manoeuvres in water, there were no 
differences in FEF25%-75% nor %VCPEF, and the flow-volume relationship showed a 
consistent pattern for F1. Additionally, FEF25%-75% and %VCPEF decreased by 27% 
and 52% respectively, and the flow-volume relationship showed clear flow 
limitations with emerging disease in M2. While spontaneously breathing on land, 
M2 also showed a 49% decrease in %VCPEF and changes in the flow-volume 
relationship indicating flow limitations when developed pneumonia. Based on 
these preliminary results, we suggest that pulmonary function testing should be 
given more attention as a non-invasive, and possibly adjunctive diagnostic 
tool, to evaluate lung health in both managed care and wild dolphins.

Reference: Borque Espinosa A., Burgos F., Dennison S., Laughlin R., Manley M., 
Capaccioni R., Fahlman A. 2020 Lung function testing as a diagnostic tool to 
assess respiratory health in bottlenose dolphins, Tursiops truncatus. Dis Aquat 
Org 138, 17-27. (doi:https://doi.org/10.3354/dao03447).

This article is open access and can be downloaded at: 
https://doi.org/10.3354/dao03447, or by request to afahl...@whoi.edu 
<mailto:afahl...@whoi.edu>

Sincerely,
Andreas

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[MARMAM] Lung function and metabolism in California sea lions

[Andreas Fahlman]

Dear All
We are happy to share our new publication looking at lung function and 
metabolic rate while at rest on land and in water for California sea lions. We 
investigated how sea lions vary respiratory flow and breath duration on land 
and in water to keep tidal volume constant. It also confirms that the tidal 
volume in marine mammals is greater as compared with terrestrial mammals but 
only about 24-30% of the vital capacity.

Abstract: Respiratory flow, expired O2, and CO2 were measured during normal 
voluntary breathing in thirteen confirmed healthy, male California sea lions 
(Zalophus californianus), body mass (Mb) range 49-130 kg. Expiratory and 
inspiratory flow (V), tidal volume (VTexp, VTinsp), and breath durations (Texp, 
Tinsp, Ttot) were collected on land (lying down in sternal recumbency and 
sitting up) and floating in water to test the hypothesis that lung function 
changes with body position and on land vs in water. For sea lions on land, no 
differences were seen in any of the lung function values when comparing lying 
down versus sitting up. However, when comparing animals in water versus on 
land, both Texp and Tinsp decreased, and expiratory and inspiratory flow 
increased while the VTexp and VTinsp remained the same. The resting mass 
specific VT (25.1 ± 1.7 ml kg-1) in the current study was approximately 24-30% 
of the estimated total lung capacity. We also measured breath-by-breath gas 
uptake to determine the O2 consumption rate (VO2) and CO2 production rates 
(VO2) during rest on land and in water. There were no differences in  VO2 or 
VCO2 on land as compared with water, and the average estimated values were 0.58 
± 0.22 l O2 min-1 (range: 0.24-1.01 l O2 min−1) and 0.50 ± 0.19 l CO2 min-1 
(range: 0.22-0.89 l CO2 min-1), respectively, which agrees with results from 
other studies in otariids. Additionally, the allometric mass-exponent for VT 
and VO2 were 1.13-1.20 and 0.86, respectively. These data are the first 
reported estimates of metabolic rate and lung function in confirmed healthy 
California sea lions.

Reference: Fahlman, A., Meegan, J., Borque-Espinosa, A., Jensen, E.D., 
Pulmonary function and resting metabolic rates in California sea lions 
(Zalophus californianus) in water and on land. 2020. Aquatic Mammals, 46:1, 
67-79.  DOI 10.1578/AM.46.1.2020.67 

The article is open access and can be downloaded at: 
https://www.aquaticmammalsjournal.org/index.php?option=com_content&view=article&id=1978&catid=185&Itemid=326
Or a pdf can be requested through afahl...@whoi.edu

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[MARMAM] Estimating energy use from acceleration

[Andreas]

Dear All
Sorry for any cross-listing but this may be of general interest to this 
community and is a new paper using acceleration to estimate energy use: 
"Estimates for energy expenditure in free-living animals using acceleration 
proxies; a reappraisal":


Wilson, R.P., Börger, L., Holton, M.D., Scantlebury, D.M., Gómez-Laich, A., 
Quintana, F., et al. (2019). Estimates for energy expenditure in free-living 
animals using acceleration proxies; a reappraisal. Journal of Animal Ecology, 
1-12. doi: 10./1365-2656.13040.

ABSTRACT

1. It is fundamentally important for many animal ecologists to quantify the 
costs of animal activities, although it is not straightforward to do so. The 
recording of
triaxial acceleration by animal‐attached devices has been proposed as a way 
forward for this, with the specific suggestion that dynamic body acceleration 
(DBA) be used as a proxy for movement‐based power.
2. Dynamic body acceleration has now been validated frequently, both in the 
laboratory and in the field, although the literature still shows that some 
aspects of DBA theory and practice are misunderstood. Here, we examine the 
theory behind DBA and employ modelling approaches to assess factors that affect 
the link between DBA and energy expenditure, from the deployment of the tag, 
through to the calibration of DBA with energy use in laboratory and field 
settings.
3. Using data from a range of species and movement modes, we illustrate that 
vectorial and additive DBA metrics are proportional to each other. Either can 
be used as a proxy for energy and summed to estimate total energy expended over 
a given period, or divided by time to give a proxy for movement‐related 
metabolic power. Nonetheless, we highlight how the ability of DBA to predict 
metabolic rate declines as the contribution of non‐movement‐related factors, 
such as heat production, increases.

If you have any questions or would like a pdf copy of the  article,  please do 
not hesitate to contact me at afahl...@whoi.edu 

Sincerely
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[MARMAM] Is the dive response an extension of the respiratory sinus arrhythmia in the dolphin?

[Andreas]

Dear All
My co-authors and I would like to share our recent publication measuring 
cardiovascular responses in the bottlenose dolphin during breath-holds at rest. 

In this paper we measure heart rate and stroke volume and calculate cardiac 
output. We correct the values for the cofounding changes in cardiac function 
associated with each breath, the Respiratory Sinus Arrhythmia, and conclude 
that the dive response is minimal. We propose that in the dolphin, the dive 
response (reduced heart rate and cardiac output) is an extension of the 
Respiratory Sinus Arrhythmia and a more generalized physiological response and 
not a specialized trait for diving.

We also provide results that suggest that dolphins can voluntarily alter heart 
rate and blood flow. This mechanism would allow them to adjust blood flow based 
on the dive they are planning, and adjust flow during the dive to alter changes 
due to metabolic demand. Voluntary adjustment of heart rate has been shown 
previously in other species, such as the harbor porpoise or sea lion, and a 
limited ability for such an adjustment have also been shown in human elite 
athletes. We propose that this ability to voluntary alter blood flow as needed 
during the dive is the key adaptation how they match demand and supply, and may 
explain how failure of this mechanism during stress can cause diving related 
issues such as the bends. 

While controversial, this new article questions the importance of the dive 
response that has for long been thought to be one of the main mechanisms for 
how diving animals can perform extended breath-holds, and argues that evolution 
has enabled dolphins and marine mammals to become efficient at voluntary 
adjustment of heart rate and blood flow to improve use of the available oxygen.

For anyone interested in this Open Access publication, the details and a link 
are below, or send me an email at afahl...@whoi.edu <mailto:afahl...@whoi.edu> 
for a pdf, or for questions of comments.

Sincerely,
Andreas

Title:Re-evaluating the significance of the dive response during voluntary 
surface apneas in the bottlenose dolphin, Tursiops truncatus
Authors:Fahlman, A.,Miedler, S., Rocho-Levine, J., Jabois, A., Arenarez, J., 
Marti-Bonmati, L., García-Párraga, D., Cauture, F.
Journal: Scientific Reports, 9, 
DOI: 10.1038/s41598-019-45064-8
URL: www.nature.com/articles/s41598-019-45064-8

Abstracts: The dive response is well documented for marine mammals, and 
includes a significant reduction in heart rate (fH) during submersion as 
compared while breathing at the surface. In the current study we assessed the 
influence of the Respiratory Sinus Arrhythmia (RSA) while estimating the 
resting fH while breathing. Using transthoracic echocardiography we measured 
fH, and stroke volume (SV) during voluntary surface apneas at rest up to 255 s, 
and during recovery from apnea in 11 adult bottlenose dolphins (Tursiops 
truncatus, 9 males and 2 females, body mass range: 140-235 kg). The dolphins 
exhibited a significant post-respiratory tachycardia and increased SV. 
Therefore, only data after this RSA had stabilized were used for analysis and 
comparison. The average (± s.d.) fH, SV, and cardiac output (CO) after 
spontaneous breaths while resting at the surface were 44 ± 6 beats min-1, 179 ± 
31 ml, and 7909 ± 1814 l min-1, respectively. During the apnea the fH, SV, and 
CO decreased proportionally with the breath-hold duration, and after 255 s 
they, respectively, had decreased by an average of 18%, 1-21%, and 12-37%. 
During recovery, the fH, SV, and CO rapidly increased by as much as 117%, 34%, 
and 190%, respectively. Next, fH, SV and CO rapidly decreased to resting values 
between 90-110 s following the surface apnea. These data highlight the 
necessity to define how the resting fH is estimated at the surface, and 
separating it from the RSA associated with each breath to evaluate the 
significance of cardiorespiratory matching during diving.

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[MARMAM] New article how breath-holding affect breathing in dolphins?

[Andreas]

Dear all,
 
Me and my co-authors are pleased to share our recent publication with you:
 Fahlman, A., Brodsky, M., Miedler, S., Dennison, S., Ivančić, M., Levine, G., 
Rocho-Levine, J., Manley, M., Rocabert, J., Borque Espinosa, A., 2019. 
Ventilation and gas exchange before and after voluntary static surface 
breath-holds in clinically healthy bottlenose dolphins, Tursiops truncatus. J. 
Exp. Biol. 222, 1-9. doi: 10.1242/jeb.192211

The article describes changes in lung function and end-expired O2 following 
status surface apneas up to 5 min in the bottle nose dolphin. 
 
A B S T R A C T
We measured respiratory flow (V̇), breathing frequency (fR), tidal volume (VT), 
breath duration and end-expired O2 content in bottlenose dolphins (Tursiops 
truncatus) before and after static surface breath-holds ranging from 34 to 292 
s. There was considerable variation in the end-expired O2, VT and fR following 
a breath-hold. The analysis suggests that the dolphins attempt to minimize 
recovery following a dive by altering VT and fR to rapidly replenish the O2 
stores. For the first breath following a surface breath-hold, the end-expired 
O2decreased with dive duration, while VT and fR increased. Throughout the 
recovery period, end-expired O2 increased while the respiratory effort (VT, fR) 
decreased. We propose that the dolphins alter respiratory effort following a 
breath-hold according to the reduction in end-expired O2 levels, allowing 
almost complete recovery after 1.2 min.
 
 The article can be found at:
http://jeb.biologists.org/content/222/5/jeb192211 
<http://jeb.biologists.org/content/222/5/jeb192211>
JEB also offers 50 free download which canoe found at:
http://jeb.biologists.org/content/jexbio/222/5/jeb192211.full.pdf?ijkey=ql8FIWLYX0Vvl2v&keytype=finite

If you have additional questions or would like a pdf copy of the article, 
please send an email to: afahl...@whoi.edu <mailto:afahl...@whoi.edu>
 
Sincerely,
Andreas
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[MARMAM] Heart rate and breathing in dolphins

[Andreas]

Dear all,
 
Me and my co-authors are pleased to share our recent publication with you:
 
Cauture, F., SterbaBoatwright, B., Miedler, S., Rocho-Levine, J., Harms, C. and 
Fahlman, A. (2019). Using Respiratory Sinus Arrhythmia to Estimate Inspired 
Tidal Volume in the Bottlenose Dolphin (Tursiops truncatus). Frontiers in 
Physiology 10. 128. doi: 10.3389/fphys.2019.00128

The article describes heart rate changes associated with breathing and uses 
these to assess how well they correlate with inspired tidal volume. In 
addition, once we correct the resting heart rate for the respiratory sinus 
arrhythmia (RSA) it appears that the resting heart rate at the surface is close 
to, or similar to the heart rate reported for diving dolphins. Consequently, 
without accounting for the RSA studies may incorrectly overestimate the 
importance of the dive response in diving dolphins. We realize this may be 
controversial but deserves further investigation.
 
A B S T R A C T
Man-made environmental change may have significant impact on apex predators, 
like marine mammals. Thus, it is important to assess the physiological 
boundaries for survival in these species, and assess how climate change may 
affect foraging efficiency and the limits for survival. In the current study, 
we investigated whether the respiratory sinus arrhythmia (RSA) could estimate 
tidal volume (VT) in resting bottlenose dolphins. For this purpose, we measured 
respiratory flow and electrocardiogram (ECG) in five adult bottlenose dolphins 
(Tursiops truncatus) at rest while breathing voluntarily. Initially, an 
exponential decay function, using three parameters (baseline heart rate, the 
change in heart rate following a breath, and an exponential decay constant) was 
used to
describe the temporal change in instantaneous heart rate following a breath. 
The three descriptors, in addition to body mass, were used to develop a 
Generalized Additive Model (GAM) to predict the inspired tidal volume (VTinsp). 
The GAM allowed us to predict VTinsp with an average (  SD) overestimate of 3  
2%. A jackknife sensitivity analysis, where 4 of the five dolphins were used to 
fit the GAM and the 5th dolphin used to make predictions resulted in an average 
overestimate of 2  10%. Future studies should be used to assess whether similar 
relationships exist in active
 
Please feel free to download the article here (open access):
 
https://www.frontiersin.org/article/10.3389/fphys.2019.00128 
<https://www.frontiersin.org/article/10.3389/fphys.2019.00128>

If you have additional questions or cannot download a copy of the paper, please 
send an email to: afahl...@whoi.edu
 
Sincerely,
Andreas
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[MARMAM] Paper on beluga lung function

[Andreas]

Dear MARMAMers
On behalf of my co-authors, I'm pleased to announce the publication of our 
article:
Characterizing respiratory capacity in belugas (Delphinapterus leucas)
Andreas Fahlman, A. Epple, A., Garcia-Parraga,D. Robeck,T. Haulena, M., 
Piscitelli-Doshkov, M., Brodsky, M. Respiraotry Physiology and Neurobiology, 
https://doi.org/10.1016/j.resp.2018.10.009
Abstract

We measured respiratory flow, breath duration, and calculated tidal volume (VT) 
in nine belugas (Delphinapterus leucas, mean measured body mass: 628 +-151 kg, 
n=5) housed in managed care facilities. Both spontaneous (resting at station) 
and trained maximal respirations (chuffs) were measured. The mean (+-s.d.) 
inspiratory VT for spontaneous breaths (16.7 +- 4.7 l, range: 7.5-18.7 l) was 
larger than those predicted based on respiratory scaling equations from 
terrestrial mammals and was 32 +- 10% of estimated total lung capacity (TLCest) 
based on an equation from static measurements made on a range of cetaceans and 
pinniped lungs, and 52 +- 18% of estimated vital capacities (VC, mean: 27.7 +- 
8.9 l, range: 16.7-40.3 l) based on respiratory measurements obtained
during trained maximal respirations. Expiratory flow (Vexp, spontaneous: 26.1 
Å} 5.5 l s−1, chuff: 66.8 +- 22.5 l s−1) was significantly higher as compared 
with inspiratory flow (Vinsp, spontaneous: 22.3 +- 4.6 l s−1, chuff: 30.1 Å} 
8.4 l s−1), and the maximal expiratory flow recorded was 212 l s–1. The breath 
duration was shorter for forced breaths (Expiration: 518 +- 101 ms; 
Inspiration: 905 +- 170 ms; Total: 1423 +- 227 ms) as compared with spontaneous 
breaths (Expiration: 995 +- 176 ms; Inspiration: 1098 +- 219 ms; Total: 2093 +- 
302 ms). These data provide baseline estimates of the respiratory capacity of 
belugas.

The full pre-print article, is available at 
https://doi.org/10.1016/j.resp.2018.10.009 

For a pdf copy, please email afahl...@whoi.edu

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[MARMAM] Two papers on deep diving, pelagic bottlenose dolphins

[Andreas]

Dear All,

We are pleased to announce that the following two papers have been published 
looking at resting metabolic rate, lung function (article 1) and theoretical 
blood and tissue gas tensions (article 2) in free-ranging bottlenose dolphin


Article 1: Fahlman A, McHugh K, Allen J, Barleycorn A, Allen A, Sweeney J, 
Stone R, Faulkner Trainor R, Bedford G, Moore MJ, Jensen FH, and Wells R (2018) 
Resting Metabolic Rate and Lung Function in Wild Offshore Common Bottlenose 
Dolphins, Tursiops truncatus, Near BermudaFront. Physiol. 9:886. doi: 
10.3389/fphys.2018.00886

URL: https://www.frontiersin.org/articles/10.3389/fphys.2018.00886/full

Abstract:
Diving mammals have evolved a suite of physiological adaptations to manage 
respiratory gases during extended breath-hold dives. To test the hypothesis 
that offshore bottlenose dolphins have evolved physiological adaptations to 
improve their ability for extended deep dives and as protection for lung 
barotrauma, we investigated the lung function and respiratory physiology of 4 
wild common bottlenose dolphins (Tursiops truncatus) near the island of 
Bermuda. We measured blood haematocrit (Hct, %), resting metabolic rate (RMR, l 
O2 min-1), tidal volume (VT, l), respiratory frequency (fR, breaths min-1), 
respiratory flow (l min-1), and dynamic lung compliance (CL, l cmH2O-1) in air 
and in water, and compared measurements with published results from coastal, 
shallow-diving dolphins. We found that offshore dolphins had greater Hct 
(56±2%) compared to shallow-diving bottlenose dolphins (range: 30-49%), thus 
resulting in a greater O2 storage capacity and longer aerobic diving duration. 
Contrary to our hypothesis, the specific CL (sCL, 0.30 ± 0.12 cmH2O-1) was not 
different between populations. Neither the mass-specific RMR (3.0±1.7 ml O2 
min-1 kg-1), nor VT (23.0 ± 3.7 ml kg-1) were different from coastal ecotype 
bottlenose dolphins, both in the wild and under managed care, suggesting that 
deep-diving dolphins do not have metabolic or respiratory adaptations that 
differs from the shallow-diving ecotypes. The lack of respiratory adaptations 
for deep diving further support the recently developed hypothesis that gas 
management in cetaceans is not entirely passive but governed by alteration in 
the ventilation-perfusion matching, which allows for selective gas exchange to 
protect against diving related problems such as decompression sickness.


Article 2: 

Fahlman A, Jensen FH, Tyack PL and Wells RS (2018) Modeling Tissue and Blood 
Gas Kinetics in Coastal and Offshore Common Bottlenose
Dolphins, Tursiops truncatus. Front. Physiol. 9:838. doi: 
10.3389/fphys.2018.00838

URL: https://www.frontiersin.org/articles/10.3389/fphys.2018.00838/full

Abstract: 
Bottlenose dolphins are highly versatile breath-holding predators that have 
adapted to a wide range of foraging niches from rivers and coastal ecosystems 
to deep-water oceanic habitats. Considerable research has been done to 
understand how dolphins manage O2 during diving, but little information exists 
on other gases or how pressure affects gas exchange. Here we used a dynamic 
multi-compartment gas exchange model to estimate blood and tissue O2, CO2 and 
N2 from high-resolution dive records of two different common bottlenose dolphin 
(Tursiops truncatus) ecotypes inhabiting shallow (Sarasota Bay) and deep 
(Bermuda) habitats. The objective was to compare potential physiological 
strategies used by the two populations to manage shallow and deep diving life 
styles. We informed the model using species-specific parameters for blood 
hematocrit, resting metabolic rate, and lung compliance. The model suggests 
that the known O2 stores were sufficient for Sarasota Bay dolphins to remain 
within the calculated aerobic dive limit (cADL), but insufficient for Bermuda 
dolphins that regularly exceeded their cADL. By adjusting the model to reflect 
the body composition of deep diving Bermuda dolphins, with elevated muscle 
mass, muscle myoglobin concentration and blood volume, the cADL increased 
beyond the longest dive duration, thus reflecting the necessary physiological 
and morphological changes to maintain their deep-diving life-style. The results 
indicate that cardiac output had to remain elevated during surface intervals 
for both ecotypes, and suggests that cardiac output has to remain elevated 
during shallow dives in-between deep dives to allow sufficient restoration of 
O2 stores for Bermuda dolphins. Our integrated modelling approach contradicts 
predictions from simple models, emphasising the complex nature of physiological 
interactions between circulation, lung compression and gas exchange.


Please email me (afahl...@whoi.edu) if you would like a PDF copy of the paper 
or if you have any questions regarding the work.

Best regards,
Andreas


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[MARMAM] A new hypothesis how stress may alter physiology and diving related trauma

[Andreas]

My co-authors and I are pleased to share our recently published article:

García-Párraga, D., Moore, M. and Fahlman, A. (2018). Pulmonary ventilation– 
perfusion mismatch: a novel hypothesis for how diving vertebrates may avoid the 
bends. Proceedings Royal Society B 285: p. 20180482-2018048.

This article is open access and copies can be downloaded at: 
http://rspb.royalsocietypublishing.org/content/285/1877/20180482 
  For further 
information, please contact afahl...@whoi.edu. 


SHORT-SYNOPSIS
How some marine mammals and turtles can repeatedly dive as deep and long as 
they do has perplexed scientists for a very long time. This review opens a new 
window through which we can take a new perspective on the question

ABSTRACT
Hydrostatic lung compression in diving marine mammals, with collapsing alveoli 
blocking gas exchange at depth, has been the main theoretical basis for 
limiting N2 uptake and avoiding gas emboli as they ascend. However, studies of 
beached and bycaught cetaceans and sea turtles imply that air breathing marine 
vertebrates may, under unusual circumstances, develop gas emboli that result in 
decompression sickness (DCS) symptoms. Theoretical modeling of tissue and blood 
gas dynamics of breath-hold divers suggests that changes in perfusion and blood 
flow distribution may also play a significant role. The results from the 
modeling work suggest that our current understanding of diving physiology in 
many species is poor, as the models predict blood and tissue N2 levels that 
would result in severe DCS severe symptoms (chokes, paralysis and death) in a 
large fraction of natural dive profiles. In this review, we combine published 
results from marine mammals and turtles to propose alternative mechanisms for 
how marine vertebrates control gas exchange in the lung, through management of 
the pulmonary distribution of alveolar ventilation (V) and cardiac output/lung 
perfusion (Q), varying the level of V/Q in different regions of the lung. 
Man-made disturbances, causing stress, could alter the V/Q  mismatch level in 
the lung, resulting in an abnormally elevated uptake of N2, increasing the risk 
for gas emboli. Our hypothesis provides avenues for new areas of research, 
offers an explanation for how sonar exposure may alter physiology causing gas 
emboli, and provides a new mechanism for how marine vertebrates usually avoid 
the diving related problems observed in human divers.

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Re: [MARMAM] Workshop

[Andreas]

Dear All
I am sorry and the date below is incorrect and should be Tuesday January 30. 
Sincerely,
Andreas

> On Jan 26, 2018, at 18:54, Andreas  wrote:
> 
> Dear All 
> The Oceanografic Foundation are organizing a workshop on biosensors that may 
> be of interest to some marine mammal enthusiasts. The workshop includes 4 
> lectures on Tuesday (January 31) by the following researchers:
> Carlos Duarte: CAASE: a new approach to ocean observation
> Rory Wilson: Tracking marine life
> Mark Meekan:  Movement of large animals at the Ocean scale
> Muhammad Hussain: New technology in animal wearables
> 
> The lectures will be streamed live starting at 18:00 (European standard time) 
> and please join us at the following link:
> 
> 
> https://www.oceanografic.org/oceanoexpertos/ 
> <https://www.oceanografic.org/oceanoexpertos/>
> 
>>  
>>  <https://www.oceanografic.org/oceanoexpertos/>
>>  
>>  
> 
> ___
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[MARMAM] Fwd: Workshop

[Andreas]

Dear All 
The Oceanografic Foundation are organizing a workshop on biosensors that may be 
of interest to some marine mammal enthusiasts. The workshop includes 4 lectures 
on Tuesday (January 31) by the following researchers:
Carlos Duarte: CAASE: a new approach to ocean observation
Rory Wilson: Tracking marine life
Mark Meekan:  Movement of large animals at the Ocean scale
Muhammad Hussain: New technology in animal wearables

The lectures will be streamed live starting at 18:00 (European standard time) 
and please join us at the following link:


https://www.oceanografic.org/oceanoexpertos/ 


>  
>  
>  
>  

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[MARMAM] New paper on energy requirements and lung function in free-ranging bottlenose dolphins

[Andreas]

Dear All,

We are pleased to announce that the following paper has been published looking 
at resting metabolic rate and lung function in free-ranging bottlenose dolphin

Fahlman, A., Brodsky, M., Wells, R., McHugh, K., Allen, J., Barleycorn, A., 
Sweeney, J. C., Fauquier, D. & Moore, M. 2018 Field energetics and lung 
function in wild bottlenose dolphins, Tursiops truncatus, in Sarasota Bay 
Florida. Royal Society Open Science 5, 171280. (DOI:10.1098/rsos.171280).
 
URL: http://rsos.royalsocietypublishing.org/content/5/1/171280

Abstract:
We measured respiratory flow-rates, and expired O2 in 32 (2-34 years, body mass 
[Mb] range: 73-291 kg) common bottlenose dolphins (Tursiops truncatus) during 
voluntary breaths on land or in water (between 2014 and 2017). The data were 
used to measure the resting O2 consumption rate ( , range: 0.76-9.45 ml O2 
min-1 kg-1) and tidal volume (VT, range: 2.2-10.4 l) during rest. For adult 
dolphins, the resting VT, but not , correlated with body mass (Mb, range: 
141-291kg) with an allometric mass-exponent of 0.41. These data suggest that 
the mass-specific VT of larger dolphins decreases considerably more than that 
of terrestrial mammals (mass-exponent: 1.03). The average resting s  was 
similar to previously published metabolic measurements from the same species. 
Our data indicate that the resting metabolic rate (RMR) for a 150 kg dolphin 
would be 3.9 ml O2 Ÿ min-1 Ÿ kg-1, and the metabolic rate for active animals, 
assuming a multiplier of 3-6, would range from 11.7-23.4 ml O2 Ÿ min-1 Ÿ kg-1. 
Our measurements provide novel data for resting energy use and respiratory 
physiology in wild cetaceans, which may have significant value for conservation 
efforts and for understanding the bioenergetic requirements of this species.

 
Please email me (afahl...@whoi.edu) if you would like a PDF copy of the paper 
or if you have any questions regarding the work.

Best regards,
Andreas


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[MARMAM] New paper on man-made disturbances in cetaceans

[Andreas]

Dear All,

We are pleased to announce that the following paper has been published which 
may be of interest to people interested in the effect of man-made disturbances 
on marine mammals (cetaceans). This is a different initiative of the journal 
Frontiers, a European open access journal which is growing rapidly. The paper 
is a review/revision of some work we have done in an attempt to define risk of 
gas emboli and decompression sickness in large whales exposed to sound. It is 
written for a younger audience and something we wanted to share.

Fahlman, A., Tyack, P. L., Miller, P. J. M. and Kvadsheim, P. H. (2017). Human 
Disturbances Might Cause Dangerous Gas Bubbles to Form in Deep-Diving Whales. 
Frontiers Young Minds 5, 62. DOI:10.3389/frym.2017.00062
 
URL: https://kids.frontiersin.org/article/10.3389/frym.2017.00062

Abstract:
Over millions of years, whales have evolved for diving in the ocean to obtain 
food while holding their breath. Because whales are air-breathing mammals, they 
eventually have to return to the ocean surface to get more oxygen. However, the 
air in the lungs also contains nitrogen, a gas that is taken up but not used by 
the body. As the whale dives deeper, the pressure from the water increases and 
more nitrogen is taken up by blood circulating from the lungs to other tissues. 
When the whale returns to the surface and the water pressure decreases, the 
nitrogen gas is returned to the lungs. If the whale spends too much time in the 
zone where nitrogen is taken up at elevated pressure, bubbles may form when the 
whale returns to the surface; similar to what happens when you open a soda 
bottle. The bubbles can cause many different problems inside the whale’s body 
and even cause death. Whales normally do not experience problems caused by 
bubbles. In recent years, scientists have discovered that when humans disturb 
whales, their dive behavior or their bodily functions may change in ways that 
increase the risk of formation of bubbles that could cause problems and death. 
A better understanding of whale behavior and how the nitrogen bubbles form may 
help scientist develop tools that can prevent these problems in whales.

 
Please email me if you would like a PDF copy of the paper or if you have any 
questions regarding the work.

Best regards,
Andreas
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[MARMAM] Decompression sickness in a marine vertebrate, the turtle

[Andreas]

Dear colleagues,

We would like to announce our new paper on defining risk variables for 
decompression sickness/Gas emboli in a marine vertebrate, the loggerhead 
turtle. While this work is about the turtle, it has wide applicability and may 
be of interest to those interested in these problems in marine mammals.
For those interested, the title and abstract are cited below:

Scientific Reports: doi: 10.1038/s41598-017-02819-5

TITLE:
Defining risk variables causing gas embolism in loggerhead sea turtles (Caretta 
caretta) caught in trawls and gillnets

AUTHORS:
A. Fahlman, J-L. Crespo, B. Sterba-Boatwright, B.A. Stacy, D. Garcia-Parraga

ABSTRACT
Incidental capture, or ‘bycatch’ in fishing gear is a major global threat to 
sea turtle populations. A recent study showed that underwater entrapment in 
fishing gear followed by rapid decompression may cause gas bubble formation 
within the blood stream (embolism) and tissues leading to organ injury, 
impairment, and even mortality in some bycaught individuals. We analyzed data 
from 128 capture events using logistic and ordinal regression to examine risk 
factors associated with gas embolism in sea turtles captured in trawls and 
gillnets. Likelihood of fatal decompression increases with increasing depth of 
gear deployment. A direct relationship was found between depth, risk and 
severity of embolism, which has not been previously demonstrated in any 
breath-hold diving species. For the trawl fishery in this study, an average 
trawl depth of 65 m was estimated to result in 50% mortality in by-caught 
turtles throughout the year. This finding is critical for a more accurate 
estimation of sea turtle mortality rates resulting from different fisheries and 
for devising efforts to avoid or minimize the harmful effects of capture.

KEYWORDS:

• Animal physiology
• Conservation biology
• Embolism

PDF available at:
https://www.nature.com/articles/s41598-017-02819-5 


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[MARMAM] New review paper on respiratory function and mechanics in pinnipeds and cetaceans

[Andreas]

Dear colleagues,

We would like to announce our review paper on respiratory function and 
physiology in marine mammals
 
For those interested, the title and abstract are cited below:
 
The Journal of Experimental Biology: doi: 10.1242/jeb.126870
 
Title:
Respiratory function and mechanics in pinnipeds and cetaceans 

Authors:
 A. Fahlman, M. Moore , D. Garcia-Parraga

Abstract
In this Review, we focus on the functional properties of the respiratory system 
of pinnipeds and cetaceans, and briefly summarize the underlying anatomy; in 
doing so, we provide an overview of what is currently known about their 
respiratory physiology and mechanics. While exposure to high pressure is a 
common challenge among breath-hold divers, there is large variation in 
respiratory anatomy, function and capacity between species – how are these 
traits adapted to allow the animals to withstand the physiological challenges 
faced during dives? The ultra-deep diving feats of some marine mammals defy our 
current understanding of respiratory physiology and lung mechanics. These 
animals cope daily with lung compression, alveolar collapse, transient 
hyperoxia and extreme hypoxia. By improving our understanding of respiratory 
physiology under these conditions we will be better able to define the 
physiological constraints imposed on these animals, and how these limitations 
may affect the survival of marine mammals in a changing environment. Many of 
the respiratory traits to survive exposure to an extreme environment may 
inspire novel treatments for a variety of respiratory problems in humans.

 
Keywords:
Compliance, marine mammal, lung function, respiratory flow, tidal volume, 
residual volume, total lung capacity, respiratory frequency, alveolar collapse
 
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[MARMAM] Paper on the effect of cardiac output on decompression sickness risk

[Andreas]

Dear Colleagues
The paper below may be of interest for those in the community that are 
interested in understanding the potential of gas emboli and decompression 
sickness in marine mammals. The study used previously published data from 
experiments on land mammals to model how the risk of decompression sickness 
scales between species of different size and for different air dive profiles. 
The main conclusion is that the majority of symptoms in air breathing mammals 
are related to variation in cardiac output. 

In breath-hold diving mammals the story is a bit more complicated, but there 
are some conclusions that can be made that are also valid for marine mammals: 
the risk of decompression sickness 1) changes with animal size, and 2) 
variation in blood flow significantly alters risk, 3) but there is no 
difference in susceptibility between species.

Abstract: A probabilistic model was used to predict decompression sickness 
(DCS) outcome in pig (70 and 20 kg), hamster (100 g), rat (220 g) and mouse (20 
g) following air saturation dives. The data set included 179 pig, 200 hamster, 
360 rat, and 224 mouse exposures to saturation pressures ranging from 1.9–15.2 
ATA and with varying decompression rates (0.9–156 ATA • min−1). Single 
exponential kinetics described the tissue partial pressures (Ptiss) of N2: 
Ptiss = ∫(Pamb – Ptiss) • τ−1 dt, where Pamb is ambient N2 pressure and τ is a 
time constant. The probability of DCS [P(DCS)] was predicted from the risk 
function: P(DCS) = 1−e−r, where r = ∫(PtissN2 − Thr − Pamb) •Pamb–1 dt, and Thr 
is a threshold parameter. An equation that scaled τ with body mass included a 
constant (c) and an allometric scaling parameter (n), and the best model 
included n, Thr, and two c. The final model provided accurate predictions for 
58 out of 61 dive profiles for pig, hamster, rat, and mouse. Thus, body mass 
helped improve the prediction of DCS risk in four mammalian species over a body 
mass range covering 3 orders of magnitude.


A copy of the paper can be downloaded at: 
http://www.nature.com/articles/srep40918
or by sending an e-mail to: afahl...@whoi.edu

Reference: Fahlman, A. (2017). Allometric scaling of decompression sickness 
risk in terrestrial mammals; cardiac output explains risk of decompression 
sickness. Scientific Reports 7, 1-9. DOI: 10.1038/srep40918

Sincerely,
Andreas


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[MARMAM] Fwd: Seminar on tag technology to study animal behavior, ecology and physiology

[Andreas]

Dear MarMamers
My excuses for the late notice of the seminar but a recorded version can be 
found at the following link:
https://www.youtube.com/watch?v=fpeUrZoM2bg 
<https://www.youtube.com/watch?v=fpeUrZoM2bg>
Sincerely
Andreas



> Begin forwarded message:
> 
> From: Andreas 
> Subject: Seminar on tag technology to study animal behavior, ecology and 
> physiology
> Date: January 18, 2017 at 20:22:17 GMT+1
> To: "MARMAM (marmam@lists.uvic.ca)" 
> 
> Dear All
> The Oceanografic Foundation would like to invite you to join us for an 
> on-line seminar on the use of tag technology to study animal behavior, 
> ecology and physiology by Rory Wilson. The seminar will available on-line at 
> the link below. We are working to provide a link so the seminar can be viewed 
> later on for those that may not be able to join us live.
> 
> Presenter: Professor Rory Wilson, Swansea University
> 
> Title: What can smart tags tell us about animals?'
> 
> Abstract: Animal-attached smart tags are getting smarter and smarter. Things 
> like acceleration, magnetic field intensity,  and pressure are now being 
> sampled at crazily  high rates. This sounds cool. But what can such tags tell 
> us about the animals that carry them. This lecture will explore some of these 
> things and perhaps air some surprises.
> 
> Time: Friday January 20, 10:30 Central European time
> 
> Streaming Link: https://www.youtube.com/watch?v=bJ5qZfUqzyQ 
> <https://www.youtube.com/watch?v=bJ5qZfUqzyQ>
> 
> 
> Sincerely,
> Andreas Fahlman

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[MARMAM] Seminar on tag technology to study animal behavior, ecology and physiology

[Andreas]

Dear All
The Oceanografic Foundation would like to invite you to join us for an on-line 
seminar on the use of tag technology to study animal behavior, ecology and 
physiology by Rory Wilson. The seminar will available on-line at the link 
below. We are working to provide a link so the seminar can be viewed later on 
for those that may not be able to join us live.

Presenter: Professor Rory Wilson, Swansea University

Title: What can smart tags tell us about animals?'

Abstract: Animal-attached smart tags are getting smarter and smarter. Things 
like acceleration, magnetic field intensity,  and pressure are now being 
sampled at crazily  high rates. This sounds cool. But what can such tags tell 
us about the animals that carry them. This lecture will explore some of these 
things and perhaps air some surprises.

Time: Friday January 20, 10:30 Central European time

Streaming Link: https://www.youtube.com/watch?v=bJ5qZfUqzyQ 
<https://www.youtube.com/watch?v=bJ5qZfUqzyQ>


Sincerely,
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[MARMAM] Respiratory physiology in Patagonia sea lions

[Andreas]

Dear MARMAM colleagues,


We​ are pleased to announce a paper on respiratory function in Patagonia sea 
lions:

Fahlman, A., Madigan, J. (2016), Respiratory function in voluntary 
participating Patagonia sea lions in sternal recumbency. Frontiers Physiology  
doi: 10.3389/fphys.2016.00528

We measured esophageal pressures (n=4), respiratory flow rates (n=5), and 
expired O2 and CO2 (n=4) in five adult Patagonia sea lions (Otaria flavescens, 
body mass range 94.3-286.0 kg) during voluntary breaths while laying down. The 
data were used to estimate the dynamic specific lung compliance (sCL, cmH2O-1), 
the O2 consumption rate (VO2) and CO2 production rates (VCO2) during rest. Our 
results indicate that the resting tidal volume in Patagonia sea lions is 
approximately 47-73% of the estimated total lung capacity. The esophageal 
pressures indicated that expiration is passive during voluntary breaths. The 
average sCL of dolphins was 0.41±0.11 cmH2O−1, which is similar to those 
measured in anesthetized sea lions and awake cetaceans, and significantly 
higher as compared with humans (0.08 cmH2O−1). The average estimated and using 
breath-by-breath respirometry were 1.023 ± 0.327 L O2 min-1 (range: 0.695-1.514 
L O2 min−1) and 0.777 ± 0.318 L CO2 min-1, (range: 0.510-1.235 L CO2 min-1), 
respectively, which is similar to previously published metabolic measurements 
from California and Steller sea lions using conventional flow-through 
respirometry. Our data provide end-tidal gas composition and provide novel data 
for respiratory physiology in pinnpeds, which may be important for clinical 
medicine and conservation efforts.

The paper is available at: 
http://journal.frontiersin.org/article/10.3389/fphys.2016.00528


Sincerely,
Andreas Fahlman

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[MARMAM] New publication on biomarkers for decompression stress in marine mammals

[Fahlman, Andreas]

Dear MarMam-ers,

We are proud to announce our new publication on biomarkers for decompression 
stress in Steller sea lions in American Journal of Physiology-Regulatory, 
Integrative and Comparative Physiology

Title: Dive, food, and exercise effects on blood microparticles in Steller sea 
lions (Eumetopias jubatus): exploring a biomarker for decompression sickness

Authors:  Andreas Fahlman, Michael J. Moore, Andrew W. Trites, David A. S. 
Rosen, Martin Haulena, Nigel Waller,  Troy Neale,  Ming Yang, and Stephen R. 
Thom

Journal: American Journal of Physiology-Regulatory, Integrative and Comparative 
Physiology
Volume: 310
Pages: R596–R601, 2016.

Abstract: Recent studies of stranded marine mammals indicate that exposure to 
underwater military sonar may induce pathophysiological responses consistent 
with decompression sickness (DCS). However, DCS has been difficult to diagnose 
in marine mammals. We investigated whether blood microparticles (MPs, measured 
as number/μl plasma), which increase in response to decompression stress in 
terrestrial mammals, are a suitable biomarker for DCS in marine mammals. We 
obtained blood samples from trained Steller sea lions (Eumetopias jubatus, 4 
adult females) wearing time-depth recorders that dove to predetermined depths 
(either 5 or 50 meters). We hypothesized that MPs would be positively related 
to decompression stress (depth and duration underwater). We also tested the 
effect of feeding and exercise in isolation on MPs using the same blood 
sampling protocol. We found that feeding and exercise had no effect on blood MP 
levels, but that diving caused MPs to increase. However, blood MP levels did 
not correlate with diving depth, relative time underwater, and presumed 
decompression stress, possibly indicating acclimation following repeated 
exposure to depth.

For reprints please e-mail Andreas Fahlman: 
andreas.fahl...@tamucc.edu<mailto:andreas.fahl...@tamucc.edu>
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[MARMAM] New Publication: Estimating energetics in cetaceans from respiratory frequency: why we need to understand physiology

[Fahlman Andreas]

Dear All
We are pleased to share our new publication “Estimating energetics in cetaceans 
from respiratory frequency: why we need to understand physiology” that was 
recently published in Biology Open. The study takes a closer look at the 
possibility of obtaining reasonable estimates of metabolic rates from breathing 
frequency in bottlenose dolphins. 
A copy of the paper can be found at: 
http://bio.biologists.org/content/biolopen/early/2016/03/16/bio.017251.full.pdf 

or by sending a request to afahl...@whoi.edu 

Title:Estimating energetics in cetaceans from respiratory frequency: why we 
need to understand physiology
Authors: Fahlman, A., van der Hoop, J., Moore, M.J., Levine, G., Rocho-Levine, 
J., Brodsky, M.
Journal: Biology Open
Year: 2016

Abstract: The accurate estimation of field metabolic rates (FMR) in wild 
animals is a key component of bioenergetic models, and is important for 
understanding the routine limitations for survival as well as individual 
responses to disturbances or environmental changes. Several methods have been 
used to estimate FMR, including accelerometer-derived activity budgets, isotope 
dilution techniques, and proxies from heart rate. Counting the number of 
breaths is another method used to assess FMR in cetaceans, which is attractive 
in its simplicity and the ability to measure respiration frequency from visual 
cues or data loggers. This method hinges on the assumption that over time a 
constant tidal volume (VT) and O2 exchange fraction (ΔO2) can be used to 
predict FMR. To test whether this method of estimating FMR is valid, we 
measured breath-by-breath tidal volumes and expired O2 levels of bottlenose 
dolphins, and computed the O2 consumption rate (V̇ O2) before and after a 
pre-determined duration of exercise. The measured V̇ O2 was compared with three 
methods to estimate FMR. Each method to estimate V̇ O2 included variable VT 
and/or ΔO2. Two assumption-based methods overestimated V̇ O2 by 216-501%. Once 
the temporal changes in cardio-respiratory physiology, such as variation in VT 
and ΔO2, were taken into account, pre-exercise resting V̇ O2 was predicted to 
within 2%, and post-exercise V̇ O2 was overestimated by 12%. Our data show that 
a better understanding of cardiorespiratory physiology significantly improves 
the ability to estimate metabolic rate from respiratory frequency, and further 
emphasizes the importance of eco-physiology for conservation management efforts.___
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[MARMAM] New publication on cardiac responses before and after exercise in dolphins

[Fahlman, Andreas]

Dear marmers,

We are proud to announce our new publication in cardiac function in bottlenose 
dolphins published in Journal of Experimental Biology.

Title: Evaluating cardiac physiology through echocardiography in bottlenose 
dolphins: using stroke volume and cardiac output to estimate systolic left 
ventricular function during rest and following exercise

Authors: Stefan Miedler, Andreas Fahlman, Mónica Valls Torres, Teresa Álvaro 
Álvarez, Daniel Garcia-Parraga

Journal: Journal of Experimental Biology  2015  218: 3604-3610;  doi: 
10.1242/jeb.131532

Abstract: Heart-rate (fH) changes during diving and exercise are well 
documented for marine mammals, but changes in stroke volume (SV) and cardiac 
output (CO) are much less known. We hypothesized that both SV and CO are also 
modified following intense exercise. Using transthoracic ultrasound Doppler at 
the level of the aortic valve, we compared blood flow velocities in the left 
ventricle and cardiac frequencies during rest and at 1, 3 and 4 min after a 
bout of exercise in 13 adult bottlenose dolphins (Tursiops truncatus, six male 
and seven female, body mass range 143–212 kg). Aortic cross-sectional area and 
ventricle blood velocity at the aortic valve were used to calculate SV, which 
together with fH provided estimates of left CO at rest and following exercise. 
fH and SV stabilized approximately 4–7 s following the post-respiratory 
tachycardia, so only data after the fH had stabilized were used for analysis 
and comparison. There were significant increases in fH, SV and CO associated 
with each breath. At rest, fH, SV and CO were uncorrelated with body mass, and 
averaged 41±9 beats min−1, 136±19 ml and 5514±1182 l min−1, respectively. One 
minute following high intensity exercise, the cardiac variables had increased 
by 104±43%, 63±11% and 234±84%, respectively. All variables remained 
significantly elevated in all animals for at least 4 min after the exercise. 
These baseline values provide the first data on SV and CO in awake and 
unrestrained cetaceans in water.

For reprints please e-mail Andreas Fahlman: 
andreas.fahl...@tamucc.edu<mailto:andreas.fahl...@tamucc.edu>
or download at: http://jeb.biologists.org/jexbio/218/22/3604.full.pdf


Andreas Fahlman
Department of Life Sciences
Texas A&M- Corpus Christi
6300 Ocean Dr Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax +1-361-825-2025
mail: andreas.fahl...@tamucc.edu<mailto:andreas.fahl...@tamucc.edu>
web: http://www.comparative-physiology.tamucc.edu/



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[MARMAM] New Paper: Lung function in Cetaceans

[Fahlman, Andreas]

Dear All
We would like to announce the publication of our recent paper on lung function 
and mechanics in cetaceans.

Title: Fahlman, A., Loring, S. H., Levine, G., Rocho-Levine, J., Austin, T. and 
Brodsky, M. (2015). Lung mechanics and pulmonary function testing in cetaceans 
Journal of Experimental Biology 218, 2030-2038.

Abstract: We measured2 and CO2 in six adult bottlenose dolphins (Tursiops 
truncatus) during voluntary breaths and maximal (chuff) respiratory efforts. 
The data were used to estimate the dynamic specific lung compliance (sCL), the 
O2 consumption rate () and CO2 production rates () during rest. Our results 
indicate that bottlenose dolphins have the capacity to generate respiratory 
flow-rates that exceed 130 l Ÿ sec-1 and 30 l Ÿ sec-1 during expiration and 
inspiration, respectively. The esophageal pressures indicated that expiration 
is passive during voluntary breaths, but active during maximal efforts while 
inspiration is active for all breaths. The average sCL of dolphins was 0.31 ± 
0.04 cmH2O-1, which is considerably higher than that of humans (0.08 cmH2O-1) 
and that previously measured in a pilot whale (0.13 cmH2O-1). The average 
estimated  and  using our breath-by-breath respirometry system ranged from 
0.857 l Ÿ O2 min-1 to 1.185 l Ÿ O2 min-1 and 0.589 l Ÿ CO2 min-1 to 0.851 l Ÿ 
CO2 min-1, respectively, which is similar to previously published metabolic 
measurements from the same animals using conventional flow-through 
respirometry. In addition, our custom-made system allows us to approximate 
end-tidal gas composition. Our measurements provide novel data for respiratory 
physiology in cetaceans, which may have significant value for clinical medicine 
and conservation efforts.

Please send an e-mail to Andreas Fahlman: 
andreas.fahl...@tamucc.edu<mailto:andreas.fahl...@tamucc.edu> if you would like 
a re-print.

Thank you
Andreas



Andreas Fahlman
Department of Life Sciences
Texas A&M- Corpus Christi
6300 Ocean Dr Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax +1-361-825-2025
mail: andreas.fahl...@tamucc.edu<mailto:andreas.fahl...@tamucc.edu>
web: http://www.comparative-physiology.tamucc.edu/



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[MARMAM] Recently published paper comparing breath-hold diving capacity in marine mammals and humans

[Fahlman, Andreas]

Dear colleagues,
We are pleased to announce the publication of our recent paper:

Title: Fahlman, A., E. Schagatay (2014). Man’s Place Among the Diving Mammals. 
Human Evolution, 29:1-3, 47-66.

Abstract: A theory was forwarded in 1960 that humans significantly deviate in 
anatomy, physiology and behavior from their closest relatives, the great apes, 
and instead resemble diving mammals, as a result of a period of selective 
pressure to enter the water (Hardy, 1960). Humans can learn how to dive and in 
many aspects resemble diving mammals, but how similar is man when compared with 
aquatic species? To evaluate this, we compared diving performances in a number 
of aquatic, semiaquatic, and terrestrial species. As an index of aquatic diving 
specialization, we used maximal and average dive depth and duration, and 
proportion of time spent under water during repeated dives. Our analysis 
indicates that aquatic “deep divers” form a separate group, to which humans – 
and most aquatic and semi aquatic mammals – do not compare in diving 
specialization. Several species perform dives of intermediate duration and to 
intermediate depths, and form a group of “moderate divers”. A great number of 
species show more modest diving skills, despite being dependent on an aquatic 
life or food sources, and form a group of “shallow divers”. Humans fit well in 
this latter group and their maximum diving capacity is well within the typical 
ability performed by shallow near shore foragers. It may be the case that, as 
most accessible food is present near the shores, a great number of air 
breathing species have specialized to utilize this niche, while only a smaller 
group have developed the specialized extreme physiology necessary for extended 
deep diving. While foraging in shallow water, humans may repeatedly dive to 20 
m and spend as much as 60% of the time submerged in shallow diving, and trained 
individuals have reached depths of 100 m on single maximal dives. From this 
perspective, human diving capacity is well within that of typical diving 
mammals.

If you would like a pdf copy of the paper, please send an e-mail to: 
andreas.fahl...@tamucc.edu<mailto:andreas.fahl...@tamucc.edu> .

Sincerely,
Andreas
Andreas Fahlman
Department of Life Sciences
Texas A&M- Corpus Christi
6300 Ocean Dr Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax +1-361-825-2025
mail: andreas.fahl...@tamucc.edu<mailto:andreas.fahl...@tamucc.edu>
web: http://www.comparative-physiology.tamucc.edu/



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[MARMAM] New publication on lung function in pinnipeds

[Fahlman Andreas]

Dear colleagues,
We are pleased to announce the publication of our recent paper: 
Title: Fahlman, A., S. H. Loring, S. Johnson, M. Haulena, A. W. Trites, V. A. 
Fravel and W. Van Bonn (2014). "Inflation and deflation pressure-volume loops 
in anesthetized pinnipeds confirms compliant chest and lungs." Frontiers in 
Physiology 5.


Abstract: We examined structural properties of the marine mammal respiratory 
system, and tested Scholander’s hypothesis that the chest is highly compliant 
by measuring the mechanical properties of the respiratory system in five 
species of pinniped under anesthesia (Pacific harbor seal, Phoca vitulina; 
northern elephant seal, Mirounga angustirostris; northern fur seal Callorhinus 
ursinus; California sea lion, Zalophus californianus; and Steller sea lion, 
Eumetopias jubatus). We found that the chest wall compliance (CCW) of all five 
species was greater than lung compliance (airways and alveoli, CL) as predicted 
by Scholander, which suggests that the chest provides little protection against 
alveolar collapse or lung squeeze. We also found that specific respiratory 
compliance was significantly greater in wild animals than in animals raised in 
an aquatic facility. While differences in ages between the two groups may 
affect this incidental finding, it is also possible that lung conditioning in 
free-living animals may increase pulmonary compliance and reduce the risk of 
lung squeeze during diving. Overall, our data indicate that compliance of 
excised pinniped lungs provide a good estimate of total respiratory compliance.

An open access copy of the article can be found at: 
http://www.frontiersin.org/Journal/Abstract.aspx?s=54&name=aquatic_physiology&ART_DOI=10.3389/fphys.2014.00433
 
<http://www.frontiersin.org/Journal/Abstract.aspx?s=54&name=aquatic_physiology&ART_DOI=10.3389/fphys.2014.00433>

If you have any questions, please do not hesitate to contact me.

Sincerely,
Andreas

Andreas Fahlman
Department of Life Sciences
Texas A&M- Corpus Christi
6300 Ocean Dr Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax +1-361-825-2025
mail: andreas.fahl...@tamucc.edu
web: http://www.comparative-physiology.tamucc.edu/



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[MARMAM] New publication: comparative analysis of marine mammal tracheas

[Andreas Fahlman]

Dear All,
We would like to draw attention to our recently published paper on the 
structural and functional properties of the conducting airways in marine 
mammals. If you would like a pdf copy of the paper, please send an 
e-mail to:

Andreas Fahlman: andreas.fahl...@tamucc.edu
or Colby Moore: colby_mo...@baylor.edu

CITATION
Moore, C., Moore, M.J., Trumble, S., Niemeyer, M., Lentell, B., 
McLellan, W., Costidis, A., Fahlman, A., A Comparative Analysis of 
Marine Mammal Tracheas. Journal of Experimental Biology 217, 1154 (2014).


ABSTRACT
In 1940, Scholander suggested that stiffened upper airways remained
open and received air from highly compressible alveoli during marine
mammal diving. There are few data available on the structural and
functional adaptations of the marine mammal respiratory system. The
aim of this research was to investigate the anatomical (gross) and
structural (compliance) characteristics of excised marine mammal
tracheas. Here, we defined different types of tracheal structures,
categorizing pinniped tracheas by varying degrees of continuity of
cartilage (categories 1–4) and cetacean tracheas by varying
compliance values (categories 5A and 5B). Some tracheas fell into
more than one category along their length; for example, the harbor
seal (Phoca vitulina) demonstrated complete rings cranially, and as
the trachea progressed caudally, tracheal rings changed morphology.
Dolphins and porpoises had less stiff, more compliant spiraling rings
while beaked whales had very stiff, less compliant spiraling rings. The
pressure–volume (P–V) relationships of isolated tracheas from
different species were measured to assess structural differences
between species. These findings lend evidence for pressure-induced
collapse and re-inflation of lungs, perhaps influencing variability in
dive depth or ventilation rates of the species investigated.

--
Andreas Fahlman
Department of Life Sciences
Texas A&M- Corpus Christi
6300 Ocean Dr Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax +1-361-825-2025
mail: andreas.fahl...@tamucc.edu
web: comparativephysiology.webs.com

--
Andreas Fahlman
Department of Life Sciences
Texas A&M- Corpus Christi
6300 Ocean Dr Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax +1-361-825-2025
mail: andreas.fahl...@tamucc.edu
web: comparativephysiology.webs.com

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[MARMAM] New review paper: How man-made interference might cause gas bubble emboli in deep diving whales

[Andreas Fahlman]

We are pleased to announce the publication of a short review that 
summarizes our current ideas how sonar may interfere with diving in 
cetaceans.


This article is an open access publication, which means that it is 
freely accessible to any reader anywhere in the world. We encourage you 
to share the article link with any colleagues who may be interested in 
this work.

**

*
Title: * How man-made interference might cause gas bubble emboli in deep 
diving whales*
*Authors: **Andreas Fahlman, Peter L Tyack, Patrick James Miller, and 
Petter H Kvadsheim

**Journal: **Frontiers in Physiology**
URL: 
**http://www.frontiersin.org/Journal/Abstract.aspx?f=65&name=physiology&ART_DOI=10.3389/fphys.2014.00013&utm_source=Email_to_authors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication&journalName=Frontiers_in_Physiology&id=66907 



*Abstract**: *

Recent cetacean mass strandings in close temporal and spatial 
association with sonar activity has raised the concern that 
anthropogenic sound may harm breath-hold diving marine mammals. Necropsy 
results of the stranded whales have shown evidence of bubbles in the 
tissues, similar to those in human divers suffering from decompression 
sickness (DCS). It has been proposed that changes in behavior or 
physiological responses during diving could increase tissue and blood 
N_2 levels, thereby increasing DCS risk. Dive data recorded from sperm, 
killer, long-finned pilot, Blainville's beaked and Cuvier's beaked 
whales before and during exposure to low- (1-2 kHz) and mid- (2-7 kHz) 
frequency active sonar were used to estimate the changes in blood and 
tissue N_2 tension (P_N2 ). Our objectives were to determine if 
differences in 1) dive behavior or 2) physiological responses to sonar 
are plausible risk factors for bubble formation. The theoretical 
estimates indicate that all species may experience high N_2 levels. 
However, unexpectedly, deep diving generally result in higher end-dive 
P_N2 as compared with shallow diving. In this focused review we focus on 
three possible explanations: 1) We revisit an old hypothesis that CO_2 , 
because of its much higher diffusivity, forms bubble precursors that 
continue to grow in N_2 supersaturated tissues. Such a mechanism would 
be less dependent on the alveolar collapse depth but affected by 
elevated levels of CO_2 following a burst of activity during sonar 
exposure. 2)_During deep dives, a greater duration of time might be 
spent at depths where gas exchange continues as compared with shallow 
dives. The resulting elevated levels of N_2 in deep diving whales might 
also make them more susceptible to anthropogenic disturbances. 3) 
Extended duration of dives even at depths beyond where the alveoli 
collapse could result in slow continuous accumulation of N_2 in the 
adipose tissues that eventually becomes a liability.**



*Citation:* Fahlman A, Tyack PL, Miller PJO and Kvadsheim PH (2014) How 
man-made interference might cause gas bubble emboli in deep diving 
whales./Front. Physiol/.*5*:13. doi: 10.3389/fphys.2014.00013




--
Andreas Fahlman
Department of Life Sciences
Texas A&M- Corpus Christi
6300 Ocean Dr Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax +1-361-825-2025
mail: andreas.fahl...@tamucc.edu
web: http://www.comparative-physiology.tamucc.edu/

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[MARMAM] Request about information on video camera gear for recording wild seals

[Andreas Salling]

Dear marmam subscribers,

My name is Andreas Salling, and I'm doing my master thesis in biology at
the University of Copenhagen, Denmark, with collaboration from Aarhus
University, Institute of BioScience, also in Denmark.

I seek any information, tips and/or experience regarding the use of camera
equipment to record video footage of seals in their natural habitat. I am
interested in the conflict with seals and fisheries, and I am particularly
curious about details in the act of stealing fish from gill nets, and hope
that experiments with stationary video recording gear can answer some of
our questions. I find myself particularly constrained by the relatively
short-lived batteries found in widely popular cameras such as the GoPro
series. I wish to record longer than the mere couple of hours which seem to
be the limit of a GoPro.

Any suggestions or tips on solving the battery-life problem will be greatly
appreciated.
Also, if anyone has knowledge on *marine camera traps*, this too will be
incredibly helpful.


Replies are welcomed at:   andreassall...@gmail.com

Hopeful regards,
Andreas.
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[MARMAM] New Publication: Activity as a proxy to estimate metabolic rate and to, partition the metabolic cost of diving vs. breathing in, pre- and post-fasted Steller sea lions

[Andreas Fahlman]

Dear All
The following paper was recently published in Aquatic Biology
Title: Activity as a proxy to estimate metabolic rate and to partition 
the metabolic cost of diving vs. breathing in pre- and post-fasted 
Steller sea lions
Authors: Fahlman, A., Svärd, C., Rosen, D. A. S., Wilson, R. P., Trites, 
A. W.

Journal: Aquatic Biology, Vol. 18: 175–184, 2013
doi: 10.3354/ab00500

Abstract: Three Steller sea lions Eumetopias jubatus, trained to dive 
voluntarily to depths ranging from 10 to 50 m, were used to determine 
whether the relationship between activity and
metabolic rate during a diving interval (MRDI, dive + surface interval) 
was affected by fasting (9 d) during the breeding season (spring through 
summer). We subsequently used the relationship between activity and MRDI 
to partition the metabolic costs between underwater breath-holding 
activity and surface breathing activities. We estimated activity from 
overall dynamic body acceleration (ODBA) measured using a 3-axis 
accelerometer, and measured MRDI using flow-through respirometry. The 
relationship between ODBA-based activity and MRDI was not affected by 
fasting period, suggesting that ODBA can be used to predict energy 
expenditure regardless of nutritional state in the spring and summer. 
However, the relationship between ODBA and dive metabolic rate differs 
from the relationship between ODBA and the surface metabolic rate before 
diving. Partitioning MRDI into the metabolic cost of remaining at the 
surface versus swimming underwater suggests that the metabolic cost of 
diving for Steller sea lions is approximately 29% lower than when 
breathing at the surface. ODBA appears to be a reasonable proxy to 
estimate metabolic rate in marine mammals, but more detailed behavioral 
data may be required to accurately apply the method in the field.


If you would like a copy, please send an e-mail to: 
andreas.fahl...@tamucc.edu


Sincerely,
Andreas

--
Andreas Fahlman
Department of Life Sciences
Texas A&M- Corpus Christi
6300 Ocean Dr Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax +1-361-825-2025
mail: andreas.fahl...@tamucc.edu
web: http://www.comparative-physiology.tamucc.edu/

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[MARMAM] New paper on the estimated blood and tissue N2 levels in odontocetes following sonar exposure

[Andreas Fahlman]

Dear All
We are happy to to announce the publication of our open access paper in Frontiers in 
Aquatic Physiology called "Estimated tissue and blood N2 levels and risk of 
decompression sickness in deep-, intermediate- and shallow diving toothed whales during 
exposure to naval sonar". (Kvadsheim, P. H., Miller, P. J. O., Tyack, P. L., Sivle, 
L. L. D., Lam, F.-P. A. and Fahlman, A. (2012). Estimated tissue and blood N2 levels and 
risk of in vivo bubble formation in deep-, intermediate- and shallow diving toothed 
whales during exposure to naval sonar. Frontiers in Physiology 3). For those that might 
be interested, the paper can be downloaded at the following link:
http://www.frontiersin.org/aquatic_physiology/10.3389/fphys.2012.00125/abstract

Sincerely,
Andreas

Abstract:
Naval sonar has been accused of causing whale stranding by a mechanism which 
increases formation of tissue N2 gas bubbles. Increased tissue and blood N2 
levels, and thereby increased risk of decompression sickness (DCS), is thought 
to result from changes in behavior or physiological responses during diving. 
Previous theoretical studies have used hypothetical sonar-induced changes in 
both behavior and physiology to model blood and tissue N2 tension (PN2), but 
this is the first attempt to estimate the changes during actual behavioral 
responses to sonar. We used an existing mathematical model to estimate blood 
and tissue N2 tension (PN2) from dive data recorded from sperm, killer, 
long-finned pilot, Blainville’s beaked and Cuvier’s beaked whales before and 
during exposure to Low- (1-2 kHz) and Mid- (2-7 kHz) frequency active sonar. 
Our objectives were; 1) to determine if differences in dive behavior affects 
risk of bubble formation, and if 2) behavioral- or 3) physiological responses 
to sonar are plausible risk factors. Our results suggest that all species have 
natural high N2 levels, with deep diving generally resulting in higher end-dive 
PN2 as compared with shallow diving. Sonar exposure caused some changes in dive 
behavior in both killer whales, pilot whales and beaked whales, but this did 
not lead to any increased risk of DCS . However, in three of eight exposure 
session with sperm whales, the animal changed to shallower diving, and in all 
these cases this seem to result in an increased risk of DCS, although risk was 
still within the normal risk range of this species. When a hypothetical removal 
of the normal dive response (bradycardia and peripheral vasoconstriction), was 
added to the behavioral response during model simulations, this led to an 
increased variance in the estimated end-dive N2 levels, but no consistent 
change of risk. In conclusion, we cannot rule out the possibility that a 
combination of behavioral and physiological responses to sonar have the 
potential to alter the blood and tissue end-dive N2 tension to levels which 
could cause DCS and formation of in vivo bubbles, but the actually observed 
behavioral responses of cetaceans to sonar in our study, do not imply any 
significantly increased risk of DCS.

--
Andreas Fahlman
Department of Life Sciences
Texas A&M- Corpus Christi
6300 Ocean Dr Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax +1-361-825-2025
mail: andreas.fahl...@tamucc.edu
web: http://www.comparative-physiology.tamucc.edu/



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[MARMAM] Recent publications on the dive response and lung function

[Fahlman, Andreas]

Dear All
We are pleased to announce the recent publication of the following papers. The 
first article is open access, and a link is provided below to the journal web 
site where the article can be downloaded. A pdf copy of the second article will 
be provided upon request. We realize that the first paper is not directly 
related to marine mammals, but it may be of interest to those interested in the 
physiological ecology of these animals.

Fahlman, A. B.L. Bostrom, K.H. Dillon, D.R. Jones. 2011. The genetic component 
of the forced diving bradycardia response
in mammals. Frontiers in Physiology. 2: 63 doi: 10.3389/fphys.2011.00063

We contrasted the forced diving bradycardia between two genetically similar 
(inbred) rat strains (Fischer and Buffalo), compared to
that of outbred rats (Wistar). The animals were habituated to forced diving for 
4 weeks. Each animal was then tested during one
40-sec dive on each of 3 days. The heart rate (fH) was measured before, during, 
and after each dive. Fischer and Buffalo exhibited
marked difference in dive bradycardia (Fischer: 120.9 ± 14.0 beats • min-1 vs. 
Buffalo: 92.8 ± 12.8 beats • min-1, P < 0.05). Outbred
rats showed an intermediate response (103.0 ± 30.9 beats • min-1) but their 
between-animal variability in mean dive fH and pre-diving
resting fH were higher than the inbred strains (P < 0.05), which showed no 
difference (P > 0.05). The decreased variability in fH in
inbred rats as compared with the outbred group indicates that reduced genetic 
variability minimizes variability of the diving bradycardia
between individuals. Heritability within strains was assessed by the 
repeatability (R) index and was 0.93 ± 0.05 for the outbred, 0.84 ± 0.16
for Buffalo, and 0.80 ± 0.12 for Fischer rats for fH during diving. Our results 
suggest that a portion of the mammalian diving bradycardia
may be a heritable trait.

http://www.frontiersin.org/aquatic_physiology/10.3389/fphys.2011.00063/abstract

Fahlman, A. S.H. Loring, M. Ferrigno, C. Moore, G. Early, M. Niemeyer, B. 
Lentell, F. Wenzel, R. Joy, M. 2011. Moore. Inflation
and deflation pressure-volume loops in breath-hold diving marine mammals. In 
Press Journal to Experimental Biology. 214:
3822-3828.

 Excised lungs from eight marine mammal species [harp seal (Pagophilus 
groenlandicus), harbor seal (Phoca vitulina), gray seal
(Halichoerus grypus), Atlantic white-sided dolphin (Lagenorhynchus acutus), 
common dolphin (Delphinus delphis), Rissoʼs
dolphin (Grampus griseus), long-finned pilot whale (Globicephala melas) and 
harbor porpoise (Phocoena phocoena)] were used
to determine the minimum air volume of the relaxed lung (MAV, N=15), the 
elastic properties (pressure–volume curves, N=24) of
the respiratory system and the total lung capacity (TLC). Our data indicate 
that mass-specific TLC (sTLC, l kg–1) does not differ
between species or groups (odontocete vs phocid) and agree with that estimated 
(TLCest) from body mass (Mb) by applying the
equation: TLCest=0.135Mb0.92. Measured MAV was on average 7% of TLC, with a 
range from 0 to 16%. The pressure–volume curves
were similar among species on inflation but diverged during deflation in 
phocids in comparison with odontocetes. These
differences provide a structural basis for observed species differences in the 
depth at which lungs collapse and gas exchange
ceases.

If you have any questions, please do not hesitate to send me an e-mail.
Sincerely,
Andreas

Department of Life Sciences
Texas A&M University-Corpus Christi
6300 Ocean Drive, Unit 5892
Corpus Christi, TX 78412
Ph. +1-361-825-3489
Fax. +1-361-825-2025
e-mail: andreas.fahl...@tamucc.edu<mailto:andreas.fahl...@tamucc.edu>

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