IMAGE-ANALYSIS OF FECAL MATERIAL GRAZED UPON BY 3 SPECIES OF COPEPODS - EVIDENCE FOR COPRORHEXY, COPROPHAGY AND COPROCHALY

Experiments involving three species of copepods (Acartia clausi Giesbrecht 1889, Pseudocalanus elongatus Boeck 1872 and Calanus finmarchicus Gunnerus 1765) incubated with freshly produced copepod faecal material were conducted and analyzed using automatic image analysis. For two species (A. clausi and C. finmarchicus) the bulk of faecal material was not ingested but was fragmented. This process, coprorhexy, was accompanied by a shift toward smaller particles in the particle size-spectrum. Increases in total volume of the faecal particles after incubation with these copepods led us to propose a process which we refer to as 'coprochaly', derived from the Greek-chi-alpha-lambda-alpha-sigma-iota-sigma, (a loosening, as of bandages). Coprochaly was promoted by manipulation of the faecal material by the copepods. For the third species (P. elongatus), coprorhexy and coprochaly were coupled with coprophagy (ingestion of faecal material). Calculations indicated that the combined effect of coprorhexy and coprochaly reduced sinking velocities of the faecal particles by up to 50%. These processes increase pelagic residency time of particles, increase substrate area for aerobic microbes and presumably enhance remineralization of particulate organic matter.