The Effects of Low Salinity Environmental Exposures on Bottlenose Dolphins (Tursiops Truncatus)
Abstract
Bottlenose dolphins (Tursiops truncatus) are a marine species with a worldwide distribution in temperate and tropical waters. Often estuarine, this species utilizes low salinity bays and freshwater rivers. Thus, these animals have homeostatic mechanisms allowing them to be in freshwater for limited periods. U.S. Navy Marine Mammal Program (MMP) dolphins travel globally and work in varied environments comparable to those in which free-ranging dolphins are observed. Exposure to low salinity is also occasionally implemented for medical treatment of MMP dolphins. These situations offer unique opportunities to examine what health effects can transpire following exposure to varied salinities. In total, retrospective analysis of 11 natural low salinity exposure events and two medical low salinity exposure events was performed. Forty-nine animals were exposed to salinity levels ranging from 0-33 parts per thousand (ppt). Serum and urine electrolytes, aldosterone, and skin changes were analyzed. Serum electrolyte aberrations were found in 28.5% of the cases with the most common aberration being mild decreases in serum sodium and chloride. Serum aldosterone was sampled in two different events and findings showed elevated serum aldosterone levels during low salinity exposure. The overall prevalence of skin lesions was 35%. The duration between the first exposure to a low salinity environment and the first documented serum electrolyte change was observed between 1-13 days. The duration between the first exposure to a low salinity environment and the first documented skin change was observed between 2-28 days. The health impacts of low salinity exposure on bottlenose dolphins are highly variable and likely dependent on multiple factors including duration and route of exposure (oral ingestion and/or skin absorption), salinity profile, environmental conditions (water quality, temperature), and individual animal health status.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 2021
- Accession Number
- AD1133417
Entities
People
- Abby M McClain
- Cynthia R. Smith
- Eric D. Jensen
- Forrest M. Gomez
- Lori H. Schwacke
- Risa L. Daniels
- Sam H Ridgway
Organizations
- Naval Information Warfare Center Pacific