Biodiversity differentials between seagrass and adjacent bare sediment change along an estuarine gradient

Differentials between the invertebrate biodiversity of seagrass (S) and adjacent bare sediment (B) were investigated at 8 localities spaced along axial gradient an estuarine system, that Knysna in South Africa; various assemblage metrics being compared paired S/B stations. Little or no S:B differentials found near mouth, but significant increase those both levels overall abundance taxon richness did occur upstream (in from <1 mouth to >2 towards head, 1 2). The habitat supporting greater therefore switched gradient. differential numbers co-dominant species assemblages also increased upstream, whereas taxonomic distinctness decreased. Functional diversity, evenness patchiness differentials, however, showed change; neither values Bray-Curtis similarity two types. Most affected epibenthic- subsurface-feeding components. As predicted, macrobenthic reacted differently gradient, enhanced much more upstream. However, location appeared equally important influence on composition presence absence seagrass. evident context-dependent nature such urges considerable caution extrapolation ecological indicators derived local areas wider regions.