Moira Décima 

Assistant Professor 

Curator - Pelagic Invertebrate Collection

Scripps Institution of Oceanography

University of California San Diego

https://mdecima.scrippsprofiles.ucsd.edu/

Title: Drivers of plankton communities and foodweb structure in a changing ocean

Abstract: Zooplankton are essential components of marine pelagic ecosystems: as trophic intermediaries they play a key role in energy transfer up the food web, they mediate biogeochemical cycling and organic export, and their month-to-year life cycles and close species links to the physical environment make them important sentinels of climate change. My research employs a multipronged approach that combines ship-board sampling and laboratory-based manipulations, using a variety of methods including, biochemical markers (bulk isotopes, amino acid isotpoes, fatty acids, DNA metabarcoding) and data assimilation tools to understand the drivers of plankton food-web structure and function within the larger context of ecosystem response to environmental forcing. I will present my research on plankton foodweb structure and biogeochemical implications in connection to zooplankton community response to physical forcing. I will focus these presentations on the two food-web pathways that determine secondary production in the ocean and impact zooplankton-mediated carbon export: the links from phytoplankton and microzooplankton to metazoan zooplankton. These trophic pathways are driven by resource availability but also impacted by the type of metazoan zooplankton: e.g., gelatinous (salps and pyrosomes) or crustacean (copepods, euphausiids) zooplankton. Importantly, increases in gelatinous zooplankton are hypothesized to be linked to climate change, and could represent fundamental shifts in ecosystem function. I will contrast trophic and biogeochemical fluxes between gelatinous- and crustacean- domination regions, demonstrating the ecosystem effects of zooplankton community composition, which also have documented shifts in response to climate change in some areas of the world. Understanding that mechanisms driving foodweb and biogeochemical pathways is needed for predicting the response of marine ecosystems to climate change, required for developing effective mitigation and sustainability plans in a rapidly changing earth system.