Copepod fecal pellets: abundance, sedimentation and content at a permanent station in the Norwegian Sea in May/June 1986

Abstract

Vertical distribution of fecal pellets and their sedimentation were studied during May and June 1986 at a permanent station on the Voering Plateau in the Norwegian Sea. Pellets were collected with water bottles as well as with moored time-series sediment traps and free-floating traps. Fecal pellets were counted, their carbon content was calculated and their composition was analyzed by scanning electron microscopy. Over 90 O/O of all suspended and sedimented fecal pellets orig~nated from copepods. Dally loss of suspended pellets from the upper 250 m of the water column via sedimentation was approx. 1 % of fecal pellet standing stock. Between 10 and 90 % of total sedimented material was attributable to these pellets; foraminifers and tintinnids accounted for the rest. It is suggested that most of the copepod pellets were broken down in the water column and/or were reingested (coprophagy). The chief constituent of both suspended and sedimented pellets was amorphous, hyalin material, in which small diatoms, coccol~thophores and coccoliths were occasionally found; large diatoms or fragments were rare. Microflagellates, which were the main autotrophs, could not be recognized in the pellets. Thus, sedimented material does not necessarily reflect species composition and abundance of phytoplankton of the upper water layers.