Genetic and meristic variations in the mummichog Fundulus heteroclitus, living in polluted and reference estuaries

Genetic and meristic variations were assessed in mummichogs (Fundulus heter oclitus) living in two sites downstream from a bleached kraft pulp mill in the Miramichi Estuary (Miramichi E,) (New Brunswick, Canada) and in four re ference estuaries. Genetic variability detected by electrophoresis of enzym es was low except for EST-3. Geographic distribution of rare alleles at fou r loci, discontinuity in allelic frequencies at the EST-3* locus and differ ences in the estimated number of migrants indicated that F. heteroclitus do es not form a panmictic population in the study area. Temporal variability in allelic frequencies at the EST-3' locus was detected only at the site cl osest to the mill (M1). The proportion of fish with high pelvic fin ray cou nts was consistently higher at site M1 and was correlated at all sites to t he proportion of fish with asymmetric fin ray counts. The possible impact o f the observed genetic discontinuity on the response of this sentinel speci es to pollutants should be considered in further studies. (C) 1999 Elsevier Science Ltd. All rights reserved.