| Summary: | Dissertation (Ph.D.) University of Alaska Fairbanks, 2018 King crab play an integral role in both marine ecosystems and fisheries; they influence benthic community structure through predation, help regulate trophic cascades, and are an important food source for large fishes, marine mammals, and humans. To sustainably manage king crab fisheries in a changing climate, it is essential to have a thorough understanding of king crab biology and behavior, as well as knowledge on how they utilize and interact with other components of the ecosystem. I investigated factors important to king crab sustainability and management, including distribution patterns and a parasitic castrator. Rhizocephalan barnacles in the genus Briarosaccus parasitize and castrate king crab hosts, thereby preventing host reproduction and potentially altering host abundance. In Alaska, prevalence is generally low (< 1% infection rate), yet higher prevalence has occurred in localized bays and fjords. I studied the larval biology of Briarosaccus regalis infecting Paralithodes camtschaticus (red king crab) to better understand how environmental factors in Alaska may influence prevalence. Maximum larval B. regalis survival occurred from 4 to 12°C and at salinities between 25 and 34. Given these parameters, current conditions in the Gulf of Alaska and Bering Sea appear favorable for high survival of B. regalis larvae. Rhizocephalans not only castrate their hosts, but they cause changes in host morphology, physiology, and behavior. I used an untargeted metabolomics (liquid chromatography mass spectrometry) approach to compare the metabolite profiles (e.g., signaling molecules, hormones) of P. camtschaticus and Lithodes aequispinus (golden king crab) with and without rhizocephalan infections. Hundreds of putative metabolites were identified, yet few differed with crab sex and no metabolites could differentiate infected from healthy crab (regardless of crab sex). There were large variations in the crab metabolome with collection year and location, ...
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