Los ostrácodos como trazadores ambientales en medios contaminados: El río Odiel (SO España)

Abstract

In this paper, ostracods are used as tracers of the environmental changes observed in the lower estuary of the Odiel River during the last decades. These microorganisms have a differential behaviour according to the sedimentary environment studied (ebb-end channels, distributaries, main channels). In the ebb-end channels draining the salt marsh bodies, the subaerial exposure is the main factor controlling the evolution of the ostracod assemblages. In the deeper distributaries and the main channel, the acid wastes derived from two industrial concentrations cause the disappearance of these microcrustaceans between 1966 and 1985. In the distributaries, a recovery was observed in the present-day sediments, whereas no individuals were collected in the main channel. The ostracod carapace is a good indicator of water pollution. Percentages of SO3, FeO and CuO are higher in the valves belonging to the pre-industrial (before 1966) and industrial periods. These components may be derived from the industrial wastes, with a latter tidal redistribution along the estuary.