Project description:Some rookeries of the western distinct population segment (WDPS) of Steller sea lions (Eumetopias jubatus) in the Aleutian Islands (Alaska, USA) have experienced continued declines since the initial collapse of the population in the 1970-1980s. Several theories have been put forward to explain the decline and lack of subsequent recovery including predation, nutritional stress, contaminants, and infectious disease agents, but thus far a primary cause has not been identified. Examining gene expression profiles of organisms has been promoted as a way to assess several health indicators related to toxicoses, infection, and nutritional stress using recent advances in metagenetics (next-generation sequencing) analyses. Next-generation sequencing may provide a more refined and adaptable method of investigating sea lion health under difficult research field collections. Here we suggest that the application of next-generation sequencing tools has the potential to evaluate the transcriptomic (gene expression) profile of animals from declining rookeries. We show that high quality RNA can be obtained from wildlife populations despite logistically challenging field conditions. We compared RNA expression in whole blood using whole transcriptome sequencing (RNA-Seq) among animals with relatively high concentrations of total mercury ([THg]) to animals with lower concentrations. There did not appear to be significant changes in gene expression in animals with high [THg] in whole blood, despite some animals having concentrations above thresholds of concern for model organisms. We did find evidence of a bias toward downregulation of some genes in animals with higher [THg].
