Marine phanerogams as a tool in the evaluation of marine trace-metal contamination: an example from the Mediterranean

New ways of evaluating the quality of the coastal marine environment in a p ractical, dependable and cost-efficient manner are continually sought. It w ould thus appear of some value to make use of bioindicator species that ref lect both the average levels and the temporal variations of contaminants at a given site. Owing to their extensive distribution in the littoral zone a nd the ecological importance of such populations, it is of interest to exam ine the potential of marine phanerogams as indicator species of metal conta mination in the marine environment. Based on results obtained in the Medite rranean, it would appear that the accumulation by marine phanerogams of met allic elements present in the environment is both extensive and specific. T he levels accumulated vary according to the metal, the species and the tiss ue type examined. In addition, the plant's physiology, which will vary with the season and/or the age of the tissues, has a significant effect on the stocking process. Nevertheless, a number of laboratory and in situ experime nts seem to indicate that the levels of contaminants that are accumulated a re a good reflection of environmental contamination. Recent studies offer n ew research outlooks with the possibility of (i) using biochemical paramete r measurements as a means of early detection and estimation of metal contam inant levels, and (ii) evaluating the current and past contamination levels for a given site by making use of the dating and memorization capacities t hat are characteristic of certain phanerogam species.