CAGE EXPERIMENTS IN AN EAST-AFRICAN MANGROVE FOREST - A SYNTHESIS

The impact of epibenthos on endobenthos has frequently been investigat ed for temperate saltmarsh regions by using cage exclusion experiments . Although the insight into the function of the endobenthos of mangrov e forests is crucial for their management, very few cage experiments h ave so far been carried out in such areas. The present paper summarise s the results of such experiments in a typical East African mangrove f orest at Gazi Bay about 60 km south of Mombasa, Kenya. Epibenthic anim als were excluded for one year in two mangrove zones which differed in forest morphology and intertidal position (Ceriops tagal and Avicenni a marina). Environmental factors and meiobenthic and macrobenthic dens ities were followed in a randomised block design, and procedural and e xclusion effects were statistically detected. In confronting the separ ate responses of all faunal groups in the two mangrove zones, this syn thesis gives a better insight into the tropho-dynamical interactions t han the earlier separate reports on the same experiment. The ecosystem of the mangrove zones and the competitive interactions within this sy stem provided an ideal opportunity to discover the existence of two fo od systems. This confirmed a strong involvement of the majority of the endobenthos in an isolated decompositional pathway in the mangrove se diment. It became clear that this exploitative competition was more im portant than the epibenthic predation in structuring and regulating th e global endobenthic community. This synthesis therefore both demonstr ates the decisive role of the endobenthos as regenators of mangrove ma terial, and suggests that endobenthos plays a minor role as prey for t he demersal or pelagic carnivores.