Vertical and seasonal distribution of eight Clausocalanus species (Copepoda: Calanoida) in oligotrophic waters

Copepods of the genus Clausocalanus Giesbrecht, 1888 are among the most abundant calanoids in the Mediterranean Sea, both in coastal and offshore regions. The vertical distribution of C. arcuicornis, C. furcatus, C. jobei, C. lividus, C. mastigophorus, C. parapergens, C. paululus, and C. pergens, which co-occur in the upper 200 m in the Gulf of Naples (Tyrrhenian Sea), was investigated during an annual sampling cycle conducted at an offshore station in 2002. The quantitative data on distribution of each species were analysed in relation to the environmental parameters. The patterns that we observed in the seasonal cycles and vertical distribution provided insights on the ecological niches of the eight Clausocalanus species.