|Molluscs as bioindicator for the ecological recovery of Ceriops tagal mangrove reafforestation|
Pecceu, B. (2006). Molluscs as bioindicator for the ecological recovery of Ceriops tagal mangrove reafforestation. MSc Thesis. VUB: Brussels. 94 pp.
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VLIZ: Non-open access 247986
|Document type: Dissertation|
Bioindicator organisms; Reafforestation; Ceriops tagal (Perr.) C.B. Robinson [WoRMS]; Cerithidea decollata (Linnaeus, 1767) [WoRMS]; Littoraria Gray, 1833 [WoRMS]; Terebralia palustris (Linnaeus, 1767) [WoRMS]; ISW, Kenya, Gazi Bay [Marine Regions]
The main objective of this study was to assess the ecological recovery of two Ceriops tagal mangrove reafforestation sites at Gazi Bay (Kenya), using molluscs as bioindicators. Four natural C. tagal stands were considered to investigate the normal abundance and biomass of molluscs. We expected to see a lower mollusc diversity and biomass in the reafforestation sites. Vegetation structure, nutritional soil parameters and physical data were analysed to find out the factors that determined the variation of molluscs in the natural stands. All considered locations were monospecific probably due to the high salinity of the substrate. Minimum 3 snail species were abundant: Terebralia palustris, Cerithidea decollate and Littoraria sp.. The latter possibly consisted of more than one species. Food availability, and shelter against desiccation and predators were controlling the abundance and biomass of the snails. The two reafforestation sites were strongly different from each other. The first site, which was the oldest, looked more successful for the recovery at first sight. The physicochemical parameters and vegetation structure were similar to the natural stands. The molluscs however revealed a low ecological recovery of the stand due to a wrong mangrove species choice during the reafforestation. The second reforested site suffered from environmental stress which resulted in a limited vegetation growth. Yet, the molluscs showed a better ecological recovery of the stand. The results of this study show that the mollusc assemblage of a reafforestation which is planted properly evolves to an assemblage similar like the one found in a natural C. tagal forest.