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 reduce time and costs, include: induced natural spawning to guarantee gamete quality, earlier exposure to the test solutions and direct observation without subsampling. In the first example of application, embryos of oysters (Crassostrea gigas) and mussels (Mytilus galloprovincialis) were used to compare the adequacy of artificial and natural seawater for the incubation of bivalve larvae. An average of 91–93% of the embryos developed normally in all cases, and there were no significant differences between species or between the two waters tested, concluding that both species and both types of water are equally suitable for ecotoxicological monitoring purposes. In the second example the C. gigas embryo-larval bioassay was used for the assessment of the water quality in 15 tributaries of an oyster farming area: the Bay of Arcachon. Methods can be applied to freshwater ecotoxicological studies.