Human exploitation and benthic community structure on a tropical intertidal mudflat

Human exploitation of intertidal marine invertebrates is known to alter benthic community structure. This study describes the impact that harvesting by women and children has on the intertidal community structure of the mudflats of the Saco on Inhaca Island, Mozambique, by comparing the benthic communities of exploited and unexploited areas. Sampling was done using two different methods: a standard core sampling method with sieving over a 1 mm mesh, and collection by the women of all animals within a 10x10 m quadrat. A number of predictions were tested on the basis of previous studies. Species richness analyses were based on multivariate non-parametric tests. The women collected in total 64 different species per tide period, their mean catch amounting to 30.5 g AFDW (Ash-Free Dry Weight) per person, 69 f which comprised predators. The crab Portunus pelagica was the dominant species in weight. Average harvest was estimated at 0.12 g AFDW m-2 y-1. The benthic community comprised 117 different species, totalling 2200 organisms m-2 or 6.0 g AFDW m-2. No impact of the exploitation could be detected for any of the following macrobenthos parameters: biomass, abundance, density or percentage of target species, predator:prey ratio, target species size, species richness, species-rank abundance, or biomass/abundance ratio. No significant correlation was found between the benthos variables obtained with the core samples and the human predation pressure. The low biomass figures for predators obtained in the Saco could be linked with the human exploitation there. The samples collected in the 10x10 m quadrats comprised <0.1 f the numerical abundance and