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Article

Physiological Effects of Low Salinity Exposure on Bottlenose Dolphins (Tursiops truncatus)

1
National Marine Mammal Foundation, 2240 Shelter Island Dr. Suite 200, San Diego, CA 92106, USA
2
U.S. Navy Marine Mammal Program, 4301 Pacific Highway, San Diego, CA 92110, USA
*
Author to whom correspondence should be addressed.
J. Zool. Bot. Gard. 2020, 1(1), 61-75; https://doi.org/10.3390/jzbg1010005
Received: 17 September 2020 / Revised: 22 October 2020 / Accepted: 9 November 2020 / Published: 12 November 2020
(This article belongs to the Special Issue Cetaceans: Conservation, Health, and Welfare)
Bottlenose dolphins (Tursiops truncatus) have a worldwide distribution in temperate and tropical waters and often inhabit estuarine environments, indicating their ability to maintain homeostasis in low salinity for limited periods of time. Epidermal and biochemical changes associated with low salinity exposure have been documented in stranded bottlenose dolphins; however, these animals are often found severely debilitated or deceased and in poor condition. Dolphins in the U.S. Navy Marine Mammal Program travel globally, navigating varied environments comparable to those in which free-ranging dolphins are observed. A retrospective analysis was performed of medical records from 46 Navy dolphins and blood samples from 43 Navy dolphins exposed to a variety of salinity levels for different durations over 43 years (from 1967–2010). Blood values from samples collected during low salinity environmental exposure (salinity ranging from 0–30 parts per thousand (ppt) were compared to samples collected while those same animals were in a seawater environment (31–35 ppt). Epidermal changes associated with low salinity exposure were also assessed. Significant decreases in serum sodium, chloride, and calculated serum osmolality and significant increases in blood urea nitrogen and aldosterone were observed in blood samples collected during low salinity exposure. Epidermal changes were observed in 35% of the animals that spent time in low salinity waters. The prevalence of epidermal changes was inversely proportional to the level of salinity to which the animals were exposed. Future work is necessary to fully comprehend the impacts of low salinity exposure in bottlenose dolphins, but the physiological changes observed in this study will help improve our understanding of the upper limit of duration and the lower limit of salinity in which a bottlenose dolphin can maintain homeostasis. View Full-Text
Keywords: salinity; bottlenose; dolphin; physiology; freshwater; osmoregulation; skin salinity; bottlenose; dolphin; physiology; freshwater; osmoregulation; skin
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MDPI and ACS Style

McClain, A.M.; Daniels, R.; Gomez, F.M.; Ridgway, S.H.; Takeshita, R.; Jensen, E.D.; Smith, C.R. Physiological Effects of Low Salinity Exposure on Bottlenose Dolphins (Tursiops truncatus). J. Zool. Bot. Gard. 2020, 1, 61-75. https://doi.org/10.3390/jzbg1010005

AMA Style

McClain AM, Daniels R, Gomez FM, Ridgway SH, Takeshita R, Jensen ED, Smith CR. Physiological Effects of Low Salinity Exposure on Bottlenose Dolphins (Tursiops truncatus). Journal of Zoological and Botanical Gardens. 2020; 1(1):61-75. https://doi.org/10.3390/jzbg1010005

Chicago/Turabian Style

McClain, Abby M., Risa Daniels, Forrest M. Gomez, Sam H. Ridgway, Ryan Takeshita, Eric D. Jensen, and Cynthia R. Smith 2020. "Physiological Effects of Low Salinity Exposure on Bottlenose Dolphins (Tursiops truncatus)" Journal of Zoological and Botanical Gardens 1, no. 1: 61-75. https://doi.org/10.3390/jzbg1010005

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