底生性カイアシ類の糞粒食・糞粒破壊行動

概要

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Faecal pellets (FP) produced by crustacean zooplankton in the epipelagic zone have been considered to sink down to deep layers because of their fast sinking velocity (>>10m d^<-1>). On the contrary, recent laboratory and field studies suggested that sinking faecal pellets were rapidly lost in and below the epipelagic layers, and one of the most likely processes can be omnivorous feeding behaviors of copepods, called as coprophagy, coprorhexy and coprochaly. This study showed feeding behaviors of benthic copepods Tigriopus sp. (Harpacticoidae) on freshly produced faecal material produced by fishes and bivalves observed using a digital video camera with a dissecting and an inverted microscope. Fish faecal material larger than Tigriopus sp. (fragmented into 3-4mm pieces) were often directly ingested and frequently fragmented into small particles by copepods. Unexpectedly high production rates of faecal pellets of 4.7h^<-1> and 5.2h^<-1> were observed for fish and bivalve faecal material, respectively. The higher ration with coprophagy than that with herbivorous feeding may be explained by superfluous feeding of Tigriopus sp. on less nutritious faecal material.
石巻専修大学の論文