Variations in Physiological Biomarkers among Mummichogs Collected from Connecticut Salt Marshes

Abstract

In fall 1998, a sample of 716 mummichogs Fundulus heteroclitus was collected from seven Connecticut salt marshes as part of an estuary biomonitoring program. The collection sites consisted of one relatively unpolluted reference site and six others with varying pollution loads. Several physiological biomarkers (body weight and length, liver weight, RNA:DNA ratio, liver somatic index, liver glycogen content, and condition index) were determined and compared with the known pollution characteristics at the collection sites. When normalized to the levels found at the reference site, average health indices were 12% lower at the low- to moderate-impact sites and 30% lower at the high-impact sites. Average health indices were more strongly depressed in female fish (18% and 35%) than in male fish (0% and 15%). For individual fish, body weight was strongly correlated with length, liver weight, condition index, and the RNA:DNA ratio. Liver glycogen content was not correlated with any of the other health indicators. This study begins to establish not only physiological biomarkers for mummichogs at several Connecticut salt marshes but also the relationship of these indicators to each other and to specific geographical locations and known pollution loads.