Polychaeta community in peri-urban equatorial and subtropical mangroves of East Africa

Abstract

Mangrove ecosystems are adversely affected by anthropogenic activities despite their great socioeconomic and environmental importance. Benthic infaunal community studies, and more specifically Polychaeta species, are a useful tool to determine the health of an ecosystem. In this study, an unbalanced ACI (After Control/Impact) design was used to compare the infaunal community structure in contaminated peri-urban mangrove swamps with nearby pristine mangroves of similar ecological traits in Kenya and Mozambique. This work, as a baseline study, found differences in Polychaeta community between peri-urban and rural, less human-impacted, mangroves in both countries. At the Kenyan study sites, it is possible to state that peri-urban mangroves suffer a larger and more severe human impact leading to a decrease of diversity and a shift to more opportunistic polychaete species. In contrast, at the Mozambican sites it seems that the peri-urban system, contaminated with domestic sewage, leads to higher Polychaeta diversity, when compared with local control sites, probably by making available more organic matter in the foodweb.

Among the polychaete community found in this study, the best tolerant families of environmental disturbance are Nereididae and Capitellidae, with Dendronereides zululandica, Perinereis vancaurica and Mediomastus sp. as main representatives.