AB prepress abstract  -  doi: 10.3354/ab00072

ABSTRACT: A wide range of anthropogenic activities are impacting on the ecology of coastal areas. Exploitation of marine resources is one such activity which, through cascading trophic effects, can have influences well beyond that of the target species. We investigated the mid-rocky shore community structure of the Azores archipelago, a seldom studied habitat, and where there is a local tradition of exploiting limpets, the main intertidal grazers. Limpet population structure differed among islands and there was an inverse relationship between the abundance of larger limpets and the human population per coastal perimeter, but not the associated catch data. At small scales of resolution (quadrats), there was a negative relationship between the cover of algae and limpets and a positive relationship between barnacles and limpets. This relationship was also apparent at the larger scale of islands as a function of the gradient of exploitation. Our results show how natural habitat fragmentation may be useful where the experimental test of hypothesis is not possible and provides evidence for the trophic cascading effects of organism removal at landscape scales.