Dear MARMAM community,

My co-authors and I are pleased to share our recent publication “The dolphin 
tap: assessing the ecosystem role of spinner dolphins in supplying nutrients to 
coral reefs in Maui Nui, Hawai‘i” in the journal Frontiers in Mammal Science.

Please find our open access article at: 
https://www.frontiersin.org/journals/mammal-science/articles/10.3389/fmamm.2025.1712553/full

Olson, G.L., Barber-Meyer S.M. and Currie J.J. (2026). The dolphin tap: 
assessing the ecosystem role of spinner dolphins in supplying nutrients to 
coral reefs in Maui Nui, Hawai‘i. Front. Mamm. Sci. 4:1712553. 
https://doi.org/10.3389/fmamm.2025.1712553.

Abstract
Introduction: Considering the ecological functioning of small cetaceans is 
important for ecosystem-based management and conservation, including their 
potential role in transporting limiting nutrients across habitats. Spinner 
dolphins (Stenella longirostris longirostris) in Hawai‘i forage nocturnally on 
mesopelagic prey offshore and, during the day, rest and avoid predators 
inshore. These predictable behavioral and spatial use patterns in the Maui Nui 
region suggest that spinner dolphins may transfer pelagic nutrients to inshore 
habitats, including shallow coral reefs - a mechanism we refer to as “the 
dolphin tap”.

Methods: To assess the role of spinner dolphins as nutrient vectors, we 
quantified spatial overlap between spinner dolphins and inshore and coral reef 
habitats in Maui Nui using vessel-based survey data collected from 2013–2022. 
We estimated nutrient deposition using standard metabolic models, spinner 
dolphin distribution and temporal overlap of dolphins with coral reef habitats

Results and Discussion: We determined spinner dolphin distribution from 51 
encounters. We estimated that an individual spinner dolphin deposited 0.10 kg N 
day-1 (SD = 0.02) into the overall marine environment. Dolphins overlapped with 
coral reef habitat during 25 encounters and 28% (SD = 36%) of total sighting 
time. Using daytime-only observations, we estimated an individual spinner 
dolphin deposited between 0.01 kg N day-1 (SD = 0.02) and 0.02 kg N day-1 (SD = 
0.03) over coral reefs, depending on the extent of nighttime deposition. 
Individual-level annual deposition values were extended to group (mean = 65.40 
individuals, SD = 45.24) and population (594 individuals) levels to quantify 
nutrient deposition in the overall marine environment and to coral reef 
habitats. 

This naturally occurring nutrient input from pelagic foraging grounds to 
inshore habitats may enhance productivity and promote coral reef resilience and 
health. Our findings provide baseline estimates of nutrient deposition by 
spinner dolphins in Maui Nui, yet additional research and monitoring are needed 
to better understand the nutrient dynamics. As Maui Nui’s coral reefs 
experience stress from warming oceans, this dolphin-mediated subsidy may become 
increasingly important for sustaining coral reef function. Protecting spinner 
dolphins is therefore essential to maintaining “the dolphin tap” nutrient 
pathway and supporting the health of Hawai‘i’s coral reef ecosystems.

Please feel free to reach out if you have any questions.

Best,
Grace

Grace Olson (she/her)

Research Biologist

Pacific Whale Foundation

300 Ma‘alaea Road Ste 211, Wailuku, HI 96793

Cell (612) 423-2618

PacificWhale.org<http://www.pacificwhale.org/>


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