METHODS article
Front. Mar. Sci.
Sec. Marine Megafauna
The Dolphin FRESH Protocol: visual Freshwater-Related Evaluation of Skin Health in free-ranging bottlenose dolphins (Tursiops spp.)
Kristi L Fazioli 1,2
Christina Toms 3,4
Ryan Takeshita 5
Alyssa Quackenbush 6
Denise Greig 7,8
Teresa Rowles 9
Lori Schwacke 10
Kathleen Colegrove 11
Ruth Y Ewing 12
Deborah Fauquier 9
Denise Boyd 13
Aaron Bouwkamp 2,6
Pádraig Duignan 14
Erin Fougeres 15
Leslie Hart 16
Sherah McDaniel 2
Timothy Morgan 17
Carrie Sinclair 12
Todd Speakman 5
Meghan Sutton 6
Heidi Whitehead 18
Vanessa Mintzer 6
1. Charted Marine Consulting, LLC, Norfolk, United States
2. Environmental Institute of Houston, University of Houston-Clear Lake, Houston, United States
3. Social Sciences Division, New College of Florida, Sarasota, United States
4. Brookfield Zoo Chicago, Sarasota Dolphin Research Program, Sarasota, United States
5. National Marine Mammal Foundation, San Diego, United States
6. Galveston Bay Foundation, Kemah, United States
7. under contract to Office of Protected Resources, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Ocean Associates Inc, Arlington, United States
8. California Academy of Sciences, San Francisco, United States
9. NOAA Office of Protected Resources, Silver Spring, United States
10. Marine Mammal Commission, Bethesda, United States
11. Zoological Pathology Program, University of Illinois Urbana-Champaign, Urbana, United States
12. NOAA Fisheries Southeast Fisheries Science Center, Miami, United States
13. Southwest Marine Mammal Field Lab, Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute, Port Charlotte, United States
14. The Marine Mammal Center, Sausalito, United States
15. NOAA Fisheries Southeast Regional Office, St. Petersburg, United States
16. School of Health Sciences, Department of Public Health Sciences and Administration, College of Charleston, Charleston, United States
17. Department of Pathobiology and Population Medicine, Mississippi State University College of Veterinary Medicine, Starkville, United States
18. Texas Marine Mammal Stranding Network, Galveston, United States
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Abstract
Exposure to freshwater is a pressing health issue for coastal bottlenose dolphins (Tursiops spp.). Environmental changes, including increased precipitation events and future coastal infrastructure projects, are altering salinity within estuarine systems. Consequently, understanding effects of freshwater exposure on dolphins and developing tools to evaluate related health conditions is urgent. To address this need, a group of veterinarians, pathologists, epidemiologists, natural resource managers, and field biologists convened to create a protocol to visually assess freshwater-related skin lesions in free-ranging bottlenose dolphins. The Dolphin FRESH (Freshwater-Related Evaluation of Skin Health) Protocol guides users without medical backgrounds to screen and evaluate photographs by focusing on the visual identification of three primary indicators of freshwater skin disease: Overgrowth, Target-like Lesions, and Light Discoloration. By determining presence of the primary indicators and scoring associated characteristics, FRESH provides users with a relative assessment of the severity of these skin anomalies, and metrics to track progressive changes. The scoring rubric performed well during systematic testing, with evaluators correctly identifying freshwater cases through recognition of primary indicators and with no significant differences in total severity scores between field biologists and medical experts. FRESH is an important step in advancing knowledge on the effects of salinity fluctuations on dolphin health. When applied to photo datasets over time, this tool will enable researchers and managers to evaluate progression and regression of freshwater skin disease, occurrence and effects of multiple exposures, and the relationship between freshwater exposure skin indicators and health and survival outcomes.
Summary
Keywords
cetacean - marine mammal, Discoloration, Freshwater (health/environment), lesions, Low salinity, Pallor, protocol & guidelines, skin disease
Received
10 November 2025
Accepted
26 January 2026
Copyright
© 2026 Fazioli, Toms, Takeshita, Quackenbush, Greig, Rowles, Schwacke, Colegrove, Ewing, Fauquier, Boyd, Bouwkamp, Duignan, Fougeres, Hart, McDaniel, Morgan, Sinclair, Speakman, Sutton, Whitehead and Mintzer. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Kristi L Fazioli
Disclaimer
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