Algae as biomarkers, bioaccumulators and toxin producers

Uncontrolled accumulation of wastes in marine environments involves an incr ease in organic substances and/or nutrients, as well as toxicity. The conse quences of this enrichment for the homeostasis of ecosystems are unpredicta ble. The best studied consequence of such enrichment is eutrophication (Con ti, 1996). Natural or anthropogenic eutrophication is the enrichment of a w ater body in nutrients, utilizable by algae. Sources of these nutrients are the atmosphere, rivers, soil erosion and runoff from catchment areas, sewa ge, industrial effluents, fertilizers, and waste disposal from animal farms . Mathematical models predicting pollutant dispersion and pollutant bioavai bility may make a substantial contribution to the study of the marine pollu tion phenomena and may be a valuable tool for the description of the pollut ion flux (Benedini and Cicioni, 1992). Generally, mathematical models refer to the propagation and transport of particular pollutants originating from one-point contamination sources and also in this case need a broad spectru m of experimental data. This requirement is particularly true for sea ecosy stems, owing to the large number of required variables and to the various e ffects on different species and ecosystems. For these reasons, biomonitorin g programmes in sea environments are very important. Establishing the pollu tant level in organisms may help to evaluate the possible toxicity for vari ous species at different levels of the trophic chain.