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Sinking Sea Pickles - The role of pyrosomes off the Oregon Coast

Pyrosoma atlanticum (pyrosome) is a warm water species of pelagic colonial tunicate that has become increasingly abundant in the Northern California Current (NCC) off the coasts of Oregon and Washington, extending as far north as the Gulf of Alaska, with substantial implications for ecosystem productivity and commercial fisheries. Pyrosomes have been recorded in the stomach contents of a number of fish species, including Pacific halibut, rockfishes, sablefish, and Pacific salmon, yet their caloric content is half that of these fish species’ preferred prey, krill. Pyrosome blooms have fouled fishing gear and filled fishing nets, with unknown immediate and long-term economic impacts. Yet we are not able to predict the frequency of these events. In this study, we are using archived time-series data of seafloor video footage collected during beam trawl surveys off the Oregon Coast between 2012 and 2018 to assess presence/absence, abundance, and biomass of pyrosomes in the California Current. In addition, by estimating pyrosome biomass, we can apply known biomass-carbon conversions for the species to estimate the role of pyrosomes in contributing to carbon flux to the seafloor. Our study will enhance scientific understanding of range expansion in P. atlanticum and its role in biogeochemical cycles off the Oregon Coast.

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