Reproductive features of sympatric species of Caprella (Amphipoda) on the southeastern Brazilian coast: a comparative study

Abstract

Caprellid amphipods play an important role in coastal ecosystems, establishing a link between producers and higher trophic levels. Also, they are sensitive to environmental changes, toxins and pollutants. The aim of the present study was to analyse the main reproductive parameters (fecundity, reproductive periodicity and juvenile recruitment) of the sympatric speciesCaprella danilevskii,C. equilibraandC. scauraassociated withSargassum cymosum(Phaeophyta, Fucales) beds on the southeastern coast of Brazil, in order to evaluate the strategies used by them to ensure their coexistence. Fecundity (F) and the volume of eggs (VE) produced varied among species, but significant relationships were observed only forC. danilevskiiandC. equilibra. It was found that the total length of females (TL) was inversely proportional to F, whereC. danilevskii, the larger species, showed a lower number of eggs, but with larger sizes. Ovigerous females ofC. scaura, despite having a total length greater than that ofC. equilibra, showed a similar volume of eggs. Ovigerous females of the three caprellid species were not retrieved in every month of the study, resulting in the observation of a reproduction of a periodic or discontinuous type, with peaks in autumn and winter. The presence of juveniles also varied throughout the study period. These variations of ovigerous females and juveniles may occur, mainly due to the fluctuation of environmental conditions, as well as the reproductive strategies exhibited by the species, allowing the coexistence ofC. danilevskii,C. equilibraandC. scaurain the study area.