The objective of this study was to report on some aspects of marine cladoceran reproduction in Guanabara Bay. Samples were collected during 1985 using a conical net with 200 mm mesh. Two species were identified: Penilia avirostris and Pseudevadne tergestina. Both species disappeared from the plankton in winter. Two months before this phenomenon, parthenogenetic females displayed reduction in brood size, while gamogenetic individuals appeared among the populations. This sequence of events is generally typical of marine cladoceran populations in temperate waters.
marine cladocerans; Penilia avirostris; Pseudevadne tergestina; Guanabara Bay; Brazil
