Research Product

As part of the Environmental Monitoring and Assessment Program in 1991, the field efficacy of six "research" indicators was examined in the estuarine systems of the Gulf of Mexico. The utility of these indicators was tested by examining those responses at both ends of multiple environmental gradients; namely, under minimally impacted conditions (reference) and heavily impacted conditions (by hypoxia, industrial discharges, agricultural runoff). In addition, the geographic effects of location (east and west of the Mississippi River) were examined. Numbers and frequencies of pathologies, abundance of splenic macrophage aggregates, and vertebral abnormalities showed response patterns that suggest wider field testing along full gradients rather than simply the extremes of the gradient are warranted. Selected blood proteins showed some promise but logistical constraints in estuarine environments may limit its utililty. Concentrations of selected organic compounds in bile showed no differences in this study between references and contaminated sites. Molecular bioindicators are discussed with regard to their potential utility as indicators of ecosystem conditions. Of these potential indicators, the use of vitellogenin assays as a measure of reproductive impairment and frequency of shell disease in selected crustaceans as an indicator of immunological aberrations deserve further examination.