Contribution by mezooplankton focal pellets to the carbon flux on Nordvestkbanken, north Norwegian shelf in 1994

Abstract

Abstract Fecal pellet production rates for mesozooplankton (> 500 µm) were measured monthly at a shelf edge and inshore station in northern Nonvegian coastal waters during Nlarch-September as part of the Ocean Margin Exchange (OMEX) stLrdy. The total potential fecal pellet carbon flux was higher at the inshore station except in May when Calanus finmarchicus (Gunnerus) was more abundant at the shelf edge. Mesozooplankton fecal pellets had the potential to contribute 2.5 % (April & September) to> 100% (May-August) of the POC flux found in sediment traps. This compared with only 5-35 %, when fecal pellet carbon flux was measured from trap pellets suggests that a significant amount of fecal pellet remineralization or coprophagy was occurring in the surface waters. Calanus finmarchicus apparently plays a pivotal role in moderating pellet carbon flux on Nordvestbanken both through its potential fecal pellet production and possibly through coprophagy. Carbon ingestion by the lccrge mesozooplankton at the shelf edge station was found to be 250 g C m-2 for the duration of the OMEX study (March-September). This is significantly higher than that estimated for new production during the course of this study suggesting that the large copepods were also feeding on detritus and/or microzooplankton. The high estimated carbon ingestion also indicates that the mesozooplankton were able to apply sufficient pressure to maintain the low chlorophyll standing stock;, observed during this study. Keywords: Fecal pellet production ratescarbon fluxOMEXsedimentation