Fauna and Flora of the Atlantic Islands : Proceedings of the 3rd Symposium, Ponta Delgada, 21-25-September 1998.The fish community of a small rocky area near Ponta Delgada, Azores, was assessed using two methods: visual census and rotenone collections. The results obtained with each method are analysed and compared. A total of 46 species was recorded for this site. The visual census recorded more species than did the rotenone collections, but each method detected species that escaped the other. The total fish diversity was found to be similar to that reported in other localized studies of littoral rocky areas of the eastern Atlantic and the
Mediterranean. Each method used revealed a different spatial structure and different
trophic relationships of the ichthyological community. The visual census put in evidence
the pelagic/demersal component, while the rotenone collections emphasized the benthic
one. Both methods agree on the importance of the benthic primary production in the
trophic food web. Visual census data further suggest that the relevance of the direct
consumption of algal material by omnivores and herbivores is greater than could be
guessed by the species diversity in this group. Strategies are discussed for combining visual and destructive sampling methods in order to achieve a more accurate representation of a given fish community
