Contribution by mesozooplankton fecal pellets to the carbon flux on Nordvestbanken, north Norwegian shelf in 1994

Fecal pellet production rates for mesozooplankton (> 500 mu m) were measure d monthly at a shelf edge and inshore station in northern Norwegian coastal waters during March-September as part of the Ocean Margin Exchange (OMEX) study. The total potential fecal pellet carbon flux was higher at the insho re station except in May when Calanus finmarchicus (Gunnerus) was more abun dant at the shelf edge, Mesozooplankton fecal pellets had the potential to contribute 2.5 % (April & September) to > 100 % (May-August) of the POC flu x found in sediment traps. This compared with only 5-35 %, when fecal pelle t carbon flux was measured from trap pellets suggests that a significant am ount of fecal pellet remineralization or coprophagy was occurring in the su rface waters, Calanus finmarchicus apparently plays a pivotal role in moder ating pellet carbon flux on Nordvestbanken both through its potential fecal pellet production and possibly through coprophagy. Carbon ingestion by the large 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 significa ntly higher than that estimated for new production during the course of thi s study suggesting that the large copepods were also feeding on detritus an d/or microzooplankton. The high estimated carbon ingestion also indicates t hat the mesozooplankton were able to apply sufficient pressure to maintain the low chlorophyll standing stocks observed during this study.