BIOMONITORING OF HEAVY-METAL AVAILABILITY IN THE MARINE-ENVIRONMENT

Biomonitors can be used to establish geographical and/or temporal vari ations in the bioavailabilities of heavy metals in the marine environm ent, offering time-integrated measures of those portions of the total ambient metal load that are of direct ecotoxicological relevance. Heav y metal biomonitors need to conform to certain required characteristic s, not least being metal accumulators, Use of a suite of biomonitors a llows recognition of the presence and relative magnitude of different metal sources, For example, a macrophytic alga responds essentially to dissolved metal sources only, a suspension feeder like a mussel respo nds to metal sources in dissolved and suspended phases, and a deposit feeder responds to metal available in the sediment. Examples are given of suitable heavy metal biomonitors in the coastal waters of Europe, New Zealand, Hong Kong and China, It is not valid to compare absolute accumulated metal concentrations in biomonitors interspecifically, alt hough interspecific comparisions of rank orders do allow cross correla tions of relative bioavailabilities of heavy metals to different biomo nitors at the same sites. There is a need to identify widespread cosmo politan biomonitors to allow intraspecific comparisons of bioavailabil ities between geographical areas. Such cosmopolitan biomonitors may in clude the alga Ulva lactuca, mussels of the genera Mytilus and Perna, the oysters Ostrea and Crassostrea, barnacles Like Balanus amphitrite and Tetraclita squamosa, and the talitrid amphipod Platorchestia plate nsis, A major caveat in the use of such cosmopolitan biomonitors remai ns the need for reliable, specific taxonomic identification.