Acknowledgements—This work was part of the European Union research project MEAM— Macrobenthos of East African Mangroves: Life Cycles and Reproductive Biology of Exploited Species. Contract no. IC18-CT96-0125. The authors would like to thank Francesca Porri, Sekiwe Mbande, Pakama Buyeye and Chumisa Thengwa for their help with field collection and cultures at Umtata, and Maria Dornelas with data processing. Acknowledgement is also due to Fundação Calouste Gulbenkian for funding the presentation of this work at the Meeting on Mangrove Macrobenthos, Kenya, 2000.