Body size and its variability in the copepod acartia margalefi (Calanoida) from Lake Acquatina (SE Italy)

Abstract

A long-term study on the body size of adult copepods was carried out on the Acartia margalefi population of Lake Acquatina in 1988–1991. Males were unusually longer than females independently from the season or the year. The specimens (both sexes) collected during cold months were longer than those collected during warm months. The body size of A. margalefi was strongly correlated with temperature. A correlation was found also with photoperiod, salinity and (but only for females) with adult sex-ratio and population density. The average body size of 1988-speci-mens proved statistically different from other years. Specimens collected from the lake were smaller than those from the sea, where in addition they did not show any sex size-dimorphism. These results suggest that the body size of A margalefi (a. species adapted to variable environments) is inversely correlated with favourable conditions for reproduction, and it shows a different variability range in the two sexes probably due to the different cost of gametogenesis in two sexes. © 1997 Taylor & Francis Group, LLC.