Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

2016

Journal

Journal Of Plankton Research

Volume

38

Issue

3

First Page

732

Last Page

750

Abstract

Copepods are important grazers on phytoplankton and contributors to carbon export, but their role is poorly understood in theWestern Antarctic Peninsula (WAP), a region of high productivity and rapid climate warming. We conducted grazing and egestion experiments with large, dominant copepods each January from 2012 to 2014. We found higher gut evacuation rates (k), initial gut pigment and ingestion rates (I) for Calanus propinquus and Rhincalanus gigas compared with Calanoides acutus. Since k and I linearly increased with chlorophyll a for most species, ingestion rates were 4-70 times greater in more productive coastal regions than offshore, slope waters. Copepods have a low grazing impact on phytoplankton biomass (< 1%) and productivity (1%, up to 11%) compared with the dominant WAP macro-and microzooplankton. Egestion rates were high (0.8-37.3 mu gC ind.(-1) day(-1)); however, similar to 58% of fecal pellets are retained in the upper water column. Daily carbon rations of similar to 1% indicated feeding on other carbon sources (protozoans and metazoans) to meet metabolic demands. However, during a coastal phytoplankton bloom, daily C rations increased to up to 13%, indicating increased reliance on phytoplankton. Future changes in theWAP plankton community may affect food web carbon flow and export.

DOI

10.1093/plankt/fbv070

Keywords

Rhincalanus-Gigas Copepoda; Particulate Organic-Carbon; Northern Barents Sea; Polar Frontal Zone; Marginal Ice-Zone; Southern-Ocean; Vertical Flux; Calanoides-Acutus; Atlantic Sector; Austral Summer

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