The vertical distribution and diurnal migrations of calanoid copepods collected on the Sond cruise, 1965 IV. Systematic account of families Lucicutiidae to Candaciidae. the relative abundance of the numerically most important genera

Abstract

The vertical distributions and diurnal migrations are analysed for nineteen species of calanoid copepods in the families Lucicutiidae up to and including the Candaciidae. The relative abundance, both vertical and horizontal, is given for each species.With few exceptions most of these species show little or no vertical migration. There is some suggestion of a reversed (downward) migration for Paracandacia bispinosa andP. simplex but since there are difficulties in analysing the surface samples the evidence is inconclusive. The species which are abundant in the family Heterorhabdidae all have little or no vertical migration and are at least partially vertically segregated by both day and night. Phyllopus impar and P. helgae are clearly vertically segregated and Haloptilus acutifrons and, to a lesser extent, H. ornatus each have two vertically separated populations by both day and night. Two size groups are present in each sex of Lucicutia flavicornis.The vertical distributions and numbers throughout the water column are analysed for 203 and 176 species in the day and night series respectively; it is concluded that while many species are relatively abundant at one or more particular depth most of them are numerically relatively insignificant in the water column as a whole. Only two species (day) and four species (night) formed more than 5 % of the total numbers caught in their respective series.The relative abundance, both vertical and horizontal, of the commonest genera are analysed. In the whole water column the relative abundance of most of the genera is constant by both day and night, and, as with the individual species, most of them are relatively scarce.