Miram Gleiber
Integrative Biology
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Presentation Time: 
2015 - 2:45pm
Copepods are important grazers on phytoplankton and contributors to carbon export through production of sinking fecal pellets, but their impact on both is poorly known along the Western Antarctic Peninsula (WAP), a region of rapid climate warming. We conducted copepod grazing and fecal pellet production experiments in the WAP each January from 2012-2014. Gut evacuation and ingestion rates linearly increased with increasing chlorophyll a for most species, with ingestion rates 4-70 times greater in the productive coastal region than in offshore waters. Copepods had a lower grazing impact on phytoplankton biomass (<1%) and productivity (1%, up to 11%) compared to the dominant macrozooplankton in the WAP. Calculated body rations indicated copepods were likely feeding on other sources of carbon (i.e., protozoans and metazoans) to meet metabolic demands, although copepod reliance on phytoplankton varied with chl a and productivity. We found high egestion rates, even in low chl a conditions, but relatively high retention of fecal pellets in the upper water column. Thus, compared to krill, copepods may not be efficient exporters of carbon to depth in this region.