A SIMPLIFICATION THE BIVALVE EMBRYOGENESIS AND LARVAL DEVELOPMENT BIOASSAY METHOD FOR WATER-QUALITY ASSESSMENT

A simplification of the standard bivalve embryo-larval bioassay method for seawater quality assessment is described. Methodological features aimed to increase reliability, sensitivity and accuracy, and to reduc e time and costs, include: induced natural spawning to guarantee gamet e quality, earlier exposure to the test solutions and direct observati on without subsampling. In the first example of application, embryos o f oysters (Crassostrea gigas) and mussels (Mytilus galloprovincialis) were used to compare the adequacy of artificial and natural seawater f or the incubation of bivalve larvae. An average of 91-93% of the embry os developed normally in all cases, and there were no significant diff erences between species or between the two waters tested, concluding t hat both species and both types of water are equally suitable for ecot oxicological monitoring purposes. In the second example the C. gigas e mbryo-larval bioassay was used for the assessment of the water quality in 15 tributaries of an oyster farming area: the Bay of Arcachon. Met hods can be applied to freshwater ecotoxicological studies. Copyright (C) 1996 Elsevier Science Ltd.