Algae as biomarkers, bioaccumulators and toxin producers

Uncontrolled accumulation of wastes in marine environments involves an increase in organic substances and/or nutrients, as well as toxicity. The consequences of this enrichment for the homeostasis of ecosystems are unpredictable. The best studied consequence of such enrichment is eutrophication (Conti, 1996). Natural or anthropogenic eutrophication is the enrichment of a water body in nutrients, utilizable by algae. Sources of these nutrients are the atmosphere, rivers, soil erosion and runoff from catchment areas, sewage, industrial effluents, fertilizers, and waste disposal from animal farms. Mathematical models predicting pollutant dispersion and pollutant bioavaibility may make a substantial contribution to the study of the marine pollution phenomena and may be a valuable tool for the description of the pollution 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 spectrum of experimental data. This requirement is particularly true for sea ecosystems, owing to the large number of required variables and to the various effects on different species and ecosystems. For these reasons, biomonitoring programmes in sea environments are very important. Establishing the pollutant level in organisms may help to evaluate the possible toxicity for various species at different levels of the trophic chain.