In-situ striped bass (Morone saxatilis) contaminant and water quality studies in the Potomac River and upper Chesapeake Bay in 1989

Abstract

In-situ striped bass contaminant studies were conducted in two important Chesapeake Bay spawning areas during the spring of 1989. The objectives of this research were to: (1) conduct three 96-h in-situ striped bass prolarval survival studies and one 27-day in-situ yearling survival study at three stations in the Potomac River during a major portion of the spawning season; (2) monitor 11 water quality parameters. 11 inorganic contaminants and 14 organic contaminants during the above experiments; (3) conduct three 96-h in-situ striped bass prolarval studies, one 14-day in-situ yearling test and one 27-day in-situ yearling test at three stations in the Upper Chesapeake Bay; (4) evaluate the water quality and contaminant conditions described in Objective (2) during these Upper Bay studies and (5) conduct histological and hematological examinations on surviving yearling striped bass tested in both the Potomac River and Upper Bay. Survival of prolarvae ranged from 3 to 33% in all three 96-h tests conducted in the Potomac River. Control survival was greater than 83%. Lowest prolarval survival was reported during the first experiment (less than 8%) when low water temperatures of 10 to 11°C were reported. These temperatures are stressful to prolarvae. Stressful conditions during the second and third experiments were not documented although 12 μg/l of arsenic was reported during experiment 3. Yearling survival during the 27-day in-situ test was 5% on the Maryland side of the river, 80% in the middle of the river and 30% on the Virginia side of the river. Control survival was 100%. Potentially stressful concentrations of chromium (29 μg/l) and arsenic (12 μg/l) were reported at the Virginia station (30% survival) during the yearling study. Stressful conditions were not documented at the Maryland station where survival was low (5%) or the middle river station where survival was high (80%). Survival of prolarvae at the three stations during Upper Chesapeake Bay tests ranged from 31 to 46% for experiment 1, 28 to 52% for experiment 2, and 6 to 22% for experiment 3. Control survival was 77% or greater. Prolarval survival during experiments 1 and 2 was considered good based on natural mortality that occurs with this life stage. The low survival during experiment 3 was likely related to the low temperatures of 10–11 °C reported during these tests. Survival of striped bass yearlings during the first 14-day yearling study ranged from 10 to 35% at the three field locations: control survival was 100%. This lest was conducted before the spawning season. Low water temperatures and temperature reductions of 7°C during short time periods were likely responsible for the reduced survival. Survival of yearlings during the 27-day yearling study (representing the spawning season) was greater than 98% al all stations. Control survival was 100%-. Although the survival of striped bass prolarvae and yearlings was generally good during these tests, it is important to note that various potentially toxic concentrations of metals (cadmium, chromium, copper and lead) were reported in the Upper Bay. The following insecticides were also reported after a major storm event in the Upper Bay between prolarval experiments 1 and 2: heptachlor epoxide ( 0.008 μg/l). edosulfan l(0.006 μg/l). dieldrin (0.005 μg/l) and 4.4-DDT (0.0014 μg/l). All contaminant concentrations were reported from composite samples: therefore, maximum values were likely much higher. Histological and hematological examinations of yearling striped bass exposed to Potomac River water suggested pathology that may be associated with water-borne contaminants. The following pathology was observed in these fish. PAS-positive inclusions of variable size and distribution in the hepatocytes of the liver, dilated kidney tubules and deposits of amorphous material near the glomerular arterioles and increased erythrocyte destruction resulting in hemoglobin in the liver and excessive accumulation and hemosiderin in the spleen. Pathology of yearlings exposed to Upper Chesapeake Bay water did not provide conclusive data to suggest the presence of contaminants. The condition of the gills from these nsh suggested a possible non-specific irritant in the water.