TWENTY-THIRD ANNUAL EASTERN FISH HEALTH WORKSHOP JOHN CARVER INN, PLYMOUTH, MA 30 MARCH - 2 APRIL, 1998 Dietary Exposures Of Striped Bass To Arsenic And Dieldrin: Effects On Pigment Distribution Within Macrophage Aggregates Kim L. Jefferson1 and Vicki S. Blazer2 1School of Forest Resources, University of Georgia, Athens, GA 30602; 2National Fish Health Laboratory, USGS/BRD, 1700 Leetown Rd, Kearneysville, WV 25430 Biomarkers are often used to assess environmental degradation and its effect on fish populations. Macrophage aggregate (MA) size, number and percent of tissue occupied by MAs have been used in a number of studies as indicators of environmental degradation. In a histochemical analysis with Perl's method for iron, the pigments hemosiderin, ceroid/lipofuscin, and melanin can be visualized within MA. We hypothesized that pigment distribution within MAs may be representative of exposure to certain types of contaminants. In a laboratory study, striped bass (Morone saxatilis) were fed 0, 50, 200, and 800 (ppm) arsenic or 0, 0.01, 0.10, 1.0, 10.0, and 25 (ppm) dieldrin. The spleens were removed from each fish and fixed for histologic preparation. Pigment distribution within MAs was determined using true color image analysis. A preliminary evaluation found significant dose-dependent increases in hemosiderin in the arsenic-fed fish, up to 200 ppm. In fish fed dieldrin there was an increase in ceroid/lipofuscin within MA. These findings may be useful in field studies for indicating contaminants of potential concern.   Return to 23rd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page