Utilizing Multidisciplinary Methods to Understand Trace Element Accumulation in Northern Gulf of Mexico Odontocetes

• Main Author: McCormack, Meaghan
• Other Authors: Dutton, Jessica, Nowlin, Weston, Roberts, Aaron, Swannack, Todd, Weckerly, Floyd
• Language: English
• Published: 2022
• Subjects: Toxicology; Dolphins; Mercury; Odontocetes; toothed whales
• Online Access: https://digital.library.txstate.edu/handle/10877/16403

Due to their long lifespan and top trophic position, odontocetes (toothed whales) can accumulate high concentrations of trace elements [e.g., cadmium (Cd), mercury (Hg)] in their tissues. In addition, for many species, their coastal distribution makes them appropriate sentinels for ecosystem and human health. Acquiring odontocete tissues for ecotoxicology studies is a challenge due to logistical and legal constraints. Although data is opportunistic, collecting tissues from deceased stranded individuals is a viable alternative to sampling free-ranging populations. In this dissertation, I focused on trace element accumulation in odontocetes, primarily bottlenose dolphins (Tursiops trunactus), that stranded along the northern Gulf of Mexico (nGOM) coast. Many samples were from dolphins that stranded during the nGOM Cetacean Unusual Morality Event (2010-2014), which provided access to an unusually large number of individuals (> 250). The primary objectives were to 1) measure the concentration of total Hg (THg) in blubber and skin from bottlenose dolphins that stranded along the Florida (FL) panhandle and Louisiana (LA) coasts and explore the relationship between total Hg (THg) concentration and sex, body length, age, stranding location, diet/relative tropic position, (δ13C and δ15N, respectively), and foraging habitat (δ34S); 2) assign bottlenose dolphins to predicted habits east and west of the Mississippi River Delta (MRD) using δ13C and δ34S values, and determine whether variation in THg concentrations could be explained by differences in trophic positions among dolphins; 3) explore the tissue-specific accumulation of Hg and selenium (Se) and the potential protective role of Se against Hg toxicity by measuring the concentrations of THg and Se in multiple tissues from 11 species of odontocetes that stranded along the FL panhandle and Louisiana coast and calculating the Se:Hg molar ratios; 4) determine the effects of long-term and short-term formalin fixation on the concentration of 14 trace elements in ...