Benthic macroinvertebrate assemblages in mangroves and open intertidal areas on the Dar es Salaam coast, Tanzania

Abstract

The assemblages of benthic macroinvertebrates in mangroves and open intertidal areas of the Dar es Salaam coast, Tanzania, was investigated in 2013–2014, revealing 56 species. Higher density, species richness and diversity were recorded in open intertidal areas, compared to nearby mangrove forests. Non-metric multidimensional scaling indicated differences in assemblages between mangrove and open intertidal samples. These differences were confirmed by analysis of similarity. SIMPER identified an average dissimilarity of 97.24% between mangroves and open intertidal samples, most of which were due to the malacostracan Uca annulipes and the gastropod Cerithidea decollata. PRIMER RELATE indicated significant correlation between macroinvertebrate assemblages and the measured physico-chemical parameters salinity, pH, redox potential and sediment particle size, whereas BIOENV and the Monte Carlo permutation test indicated that redox potential, sediment particle size and pH contributed significantly to variation in species composition. Mangroves were dominated by the gastropod C. decollata, and by the malacostracans Neosarmatium africanum and U. annulipes, and open intertidal areas by the bivalves Dosinia hepatica and Eumarcia paupercula. Due to the rich biodiversity in open intertidal ecosystems, it is recommended that conservation efforts along the Tanzanian coast should focus here.