Characterizing ocean change impacts on three marine species vital to recreational, subsistence, and commercial fisheries in Alaska

Abstract

Global climate change, facilitated by increased greenhouse gas production, is driving physical and chemical alterations to the marine environment, including a long-term decrease in oceanic pH, referred to as ocean acidification (OA), and an increase in global marine temperature, referred to as ocean warming (OW). Alterations to the chemistry and temperature of the marine environment may result in bottom-up community restructuring mediated by changes in food web dynamics. In Alaska, there are many species-specific knowledge gaps, thus necessitating an assessment of the potential sensitivity of said species to climate change-related conditions. Pacific razor clams (Siliqua patula), bidarkis (Katharina tunicata), and pink salmon (Oncorhynchus gorbuscha) are prominent species utilized by Alaska’s recreational, subsistence, and commercial fisheries, respectively. This dissertation examines how, and to what extent, anthropogenically forced ocean change impacts these organisms, while simultaneously bridging knowledge gaps regarding their development and biomineralogy. This research 1) characterized the embryonic and early larval development of S. patula, and 2) examined the developmental and biomineralogical responses of S. patula in Alaska to elevated and variable pCO2 conditions. Additionally, I 3) investigated the impact of future OA and OW conditions on bidarki physiology, biomineralogy, and behavior, and 4) assessed the impact of both elevated pCO2 and reduced food availability on juvenile pink salmon. My research yielded several novel discoveries. Firstly, shell development in S. patula involves a unique concretion development process, which could leave this species vulnerable to dissolution in an acidic environment, and the developmental rate of S. patula concretions is accelerated under future OA conditions. Secondly, results suggest that bidarkis are resilient to future conditions of OA and OW. In addition, bidarkis exert a strong level of biomineralogical control under OA conditions, as calcification increased within the pleural shell margin (despite observed de-silicification) and display no evidence of dissolution in the jugal lamina. This robust response could position bidarkis as particularly successful grazers in the rocky intertidal of a future warmer and more acidic ocean. Juvenile pink salmon displayed the most sensitivity to ocean change of the species investigated here, experiencing significant reductions in conditional index and mass, significant increases in cortisol levels and routine metabolic rate, while producing significantly larger otoliths (mass-corrected) under elevated pCO2 conditions. The interaction between elevated pCO2 and reduced food availability also altered caudal fin morphology significantly.