Speaker: Anela Choy, Associate Professor, Scripps Institution of Oceanography, University of California San Diego

Topic:

Quantitative sampling of animal communities that span the oceanic water column is central to understanding the dynamics of deep-sea food web structure, biogeochemical cycling, and resource management. Midwater communities inhabit Earth’s largest habitat by volume and include representatives from nearly all major marine animal phyla. Thus, fostering taxonomic expertise and developing sampling and laboratory methods to comprehensively describe these communities is key to drawing food web connections and assessing spatial and temporal dynamics in the sea. In the eastern boundary upwelling system of the southern California Current Ecosystem, we have been sampling and quantifying micronekton communities with a 10m² MOCNESS between the surface and ~2,000 m to understand their horizontal and vertical dynamics. Across five annual cruises, we quantify community composition at seven stations within deep basins, the escarpment, and offshore stations along a ~700 km transect. We identified over 140 families of fishes, crustaceans, molluscs, gelatinous plankton and other invertebrates. This seminar will present preliminary results examining distance from shore as a proxy for environmental variability along our transect, looking at the effects of depth, sampling time, and station on community biomass, composition, and vertical patterns. To understand the connectivity of these communities across epipelagic, mesopelagic, and upper-bathypelagic depth horizons, we are also measuring stable carbon and nitrogen isotope compositions of dominant species, migrators, and residents. Our goal is to refine our understanding of the ecological roles of deep pelagic animal communities and how these animals shape biogeochemical cycling and dynamically connect ecosystems.