Ecology of southern African estuaries Part XI. Mngazana: a mangrove estuary in Transkei

Open Access
Publisher Website
Google Scholar
Abstract
Mngazana is a rich estuary dominated by mangroves and containing a diversity of both invertebrates and fish. Its richness is mainly due to favourable physical conditions. The invertebrate fauna includes temperate, tropical, and subtropical species, predominating in the lower reaches, middle reaches and head respectively. The fish have affinities with the tropics in summer, while in winter many warm-temperate species increase in numbers. In comparison with the fauna of soft substrates, that of rocks has a higher percentage of stenohaline and estuarine forms, and a more restricted distribution. The rocky habitat in estuaries favours greater specialization with respect to salinity tolerance. A high percentage of the biomass of invertebrates in soft substrates consists of detritivores, and the biomass is related to the organic content of the substrate. Mangrove mud has the hlghest organic content and supports the highest biomass, but few species can tolerate the conditions there. Mangroves are probably the major primary producers in the system. Mngazana is 'n ryk riviermond gekenmerk deur wortelbome en 'n verskeidenheid van invertebrate en visse. Dit het gunstige fisiese omstandighede.lnvertebrate sluit in gematigde, tropiese en subtropiese spesies wat in die lae, middel en bolope oorheers. Die visse toon verwantskappe met die trope gedurende die somer en baie warm-gematigde spesies vermeerder gedurende die winter. In vergelyking met die fauna van sagte (bodems), het die van rotse 'n hoe persentasie stenohaliene en riviermond-vorme en 'n meer beperkte verspreiding. Die rotsagtige habitat in riviermonde begunstig groter spesialisasie met betrekking tot soutgehalte verdraagsaamheid. 'n Hoe persentasie van die biomassa van invertebrate in sagte bodems bestaan uit detritus-voeders en is in verhouding tot die organiese inhoud van die bodem. Wortelboom-modder het die hoogste organiese inhoud en onderhou die grootste biomassa, maar min spesies kan die toestande daar oorleef. Wortelbome is waarskynlik die belangrikste primere produsente in die sisteem.

This publication has 0 references indexed in Scilit: