Inter- and Intralaboratory Variability of Marine Chronic Toxicity Test Methods, 1995 Environmental Conference Proceedings

R.A. Pastorok

M.K. Butcher

J.E. Sexton

PTI Environmental Services

G. Cherr

Bodega Marine Laboratory

R. Caldwell

Northwestern Aquatic Sciences

P. Chapman

EVS Environmental Consultants

J. W. Anderson

Columbia Aquatic Sciences

P. Dinnel

Dinnel Marine Research

R. Cardwell

Parametrix

Biomonitoring of effluents is being incorporated into National Pollutant Discharge Elimination System permits for industrial wastewater discharges in Washington State. This study evaluated inter- and intralaboratory variability of EC50 values in four chronic marine bioassay protocols that may be used to evaluate the toxicity of complex effluents: 1) bivalve larval developmental abnormality, using the oyster Crassostrea gigas or the mussel Mytilus sp., 2) echinoderm fertilization, using the sand dollar Dendraster excentricus or the sea urchin Strongylocentrotus purpuratus, 3) fish growth, using the inland silverside Menidia beryllina, and 4) kelp sexual reproduction, using the brown alga Laminaria saccharina. Five commercial labora-tories conducted several round-robin tests of fresh effluent samples from two pulp and paper mills (representing a bleached kraft process and a bleached sulfite process) and two reference toxicants (CdCl2 and lyophilized effluent from a pulp and paper mill). Monthly testing of the two reference toxicants was performed for 13 months using the bivalve and echinoderm tests. The bivalve test was usually less variable than the echinoderm test. Hypothesis tests using analysis of variance on EC50 values for these two tests revealed significant bivalve and echinoderm phyla. The kelp reproduction test usually provided results, although both inter- and intralaboratory variability were high. The fish growth test did not yield sufficient numbers of EC50 estimates for an analysis of inter-and intralaboratory variability. Overall, the order of assay sensitivity, from most to least sensitive, was C. gigas abnormality, Mytilus sp. abnormality, D. excentricus fertilization, S. purpuratus fertilization, L. saccharina reproduction, and M. beryllina growth.