Taxonomic and Functional Assessment of Subtidal Macrobenthic Communities in the Bahía Blanca Estuary (Argentina)

Abstract

The macrobenthic communities in the soft-bottom subtidal areas of the BahíaBlanca Estuary are dominated by polychaetes, crustaceans, and mollusks. Speciesrichness, abundance, biomass, and taxonomic and functional diversity of themacrobenthic communities vary between the myxohaline and euhaline zones.These biological descriptors of the macrobenthic communities also vary betweenzones located near urban and industrial effluent discharges compared to thoselocated farther away. For the whole area studied, 155 morphospecies are listed with dominance of the polychaetes Nicolea sp. and Leodamas verax in themyxohaline zone, Terebellides totae in the middle zone, and Axiothella sp. andthe bivalve Corbula patagonica in the euhaline zone. Also, the polychaeteLaeonereis acuta was dominant in the vicinity of sewage discharges. Mostorganisms are deposit-feeders and lack calcified bodies. There are more smallsized (<1 cm), discretely motile and burrowing organisms in the myxohaline zonethan in the euhaline zone, which has more medium-sized (1?5 cm) and motileorganisms. The ecological role of burrowing and deposit-feeding organisms, suchas bioturbators, potentially promoting the bioavailability of contaminatingsubstances, is highlighted throughout the chapter. There are several sources ofanthropogenic disturbance, presumably acting synergistically and cumulatively.Based on the macrobenthic community, the affected areas are detected nearsewage and industrial discharges. The inner area of the Bahía Blanca Estuaryshows greater environmental sensitivity with the highest anthropogenic pressure.