Using bioassays for testing seawater quality in Greece

Abstract

The purpose of this study is to show the seawater quality in the Thermaikos Gulf, the Pagassitikos Gulf and Skiathos island in the Northern Aegean Sea. The assessment of coastal water quality presented here is based on two bioassays that use marine organisms as indicators of seawater quality, the invertebrate Artemia franciscana and the marine bioluminescent bacterium Vibrio fischeri. Bioassays are necessary in water pollution evaluations as physical and chemical tests alone are not sufficient to assess potential effects on aquatic organisms. According to our results, there was an improvement in coastal water quality in the Thermaikos Gulf between September 1997 and April- May 2000. In the Pagassitikos Gulf the coastal water quality was generally good in April- May 2000, while in October 1999 it was generally poor. Between the two bioassays that we used in this study, the Microtox test, which uses the marine bacterium Vibrio fischeri as a test organism, was more sensitive in detecting toxicity in seawater.