Alan W. McIntosh

Sublethal effects of heavy metal contaminated sediment on midge larvae (Chironomus tentans)

Chironomid larvae were maintained for 17 days in sediments with various heavy metal levels. The control sediment had levels of 0.6 ppm cadmium, 17 ppm chromium and 77 ppm zinc. The most contaminated sediment had levels of 1030 ppm cadmium, 1640 ppm chromium, and 17300 ppm zinc.The mean length and weight of the larvae from the control sediment were 1.83 cm and 2.86 mg. The mean length and weight of larvae from the most contaminated sediment were 0.82 cm and 0.20 mg. A linear relationship was found for the square root of length versus metal levels in the sediment.

Emergence of the midge chironomus tentans when exposed to heavy metal contaminated sediment

This experiment tested the effects of heavy metal contaminated sediment on emergence of chironomids. The number of adults emerging from test chambers containing an uncontaminated sediment and ones with sediment containing 1030 ppm cadmium (Cd), 17,300 ppm zinc (Zn), and 1640 ppm chromium (Cr) were observed for 14 days. It was found that emergence was reduced by over three times and delayed for two days in the heavy metal contaminated sediment.

Avoidance response of Midge Larvae (Chironomus Tentans) to sediments containing heavy metals

Avoidance reactions of chironomid larvae to contaminated sediment taken from a heavy metal impacted lake were studied. Heavy metal levels in the test sediment ranged from background of 0.6 parts per million (ppm) cadmium, 77 ppm zinc and 17 ppm chromium to a maximum of 1,029 ppm cadmium, 17,262 ppm zinc and 2,106 ppm chromium. A linear relationship was established between cadmium and zinc levels in the sediment and avoidance by chironomids.An approximate threshold avoidance of metals in the sediment was determined to be between 213–422 ppm cadmium, 4385–8330 ppm zinc and 799–1513 ppm chromium.

Sediment contamination and benthic macroinvertebrate distribution in a metal-impacted lake

Abstract Sediment contamination and benthic macroinvertebrate distribution were studied in Palestine Lake, Indiana, a public 80-ha system contaminated by effluents from a nearby electroplating plant. Trace metal levels in the upper 3 cm of sediment ranged from a high of 969 ppm cadmium, 14,032 ppm zinc and 2106 ppm chromium (dry weight basis) near the influent ditch, to a low of 4 ppm cadmium, 139 ppm zinc and 38 ppm chromium in the uncontaminated eastern basin of the lake. The midge Chironomus tentans was absent from areas of highest contamination; how ver, midge numbers increased to an average of 28 individuals/grab sample in the eastern basin. Specimens of the aquatic oligochaete Limnodrilus sp. were abundant (89/sample) in the most heavily impacted areas of the lake and scarce (3·4/sample) in the eastern basin.

Evidence of resistance to metals in larvae of the midge Chironomus tentans in a metal contaminated lake.

Currently the existence of toxicant resistant strains of aquatic invertebrates is of interesto Recently BRYAN (1974) noted tolerance of copper and zinc but not cadmium or lead in the polychaete Nereis diversicolor taken from polluted Engllsh estuaries. LUOMA (1977) has suggested that resistance testing may be used to indicate which contaminants are of primary concern in aquatic systems. In the current study, chlronomid larvae (Chironomus tentans) were collected from two areas, one contaminated by heavy metals and one uncontaminated, of Palestine Lake, Indiana, and subjected to a series of laboratory tests to determine if metal resistant strains have developed within the lake.

Trace Metal Contamination of Bluegill (Lepomis macrochirus) from Two Indiana Lakes

Abstract Bluegill (Lepomis macrochirus) from two industrially contaminated Indiana lakes were analyzed for cadmium, zinc, and lead content. Bluegill collected from several uncontaminated sites were used to establish background metal concentrations. The highest mean concentrations of Cd and Zn were found in Palestine Lake bluegill (3.4 μg Cd/g and 220 μg Zn/g) and the highest mean concentration of Pb was found in Little Center lake bluegill (6.1 μg Pb/g). These mean concentrations were significantly higher than background.

Acute lethality and effects of sublethal cadmium exposure on ventilation frequency and cough rate of bluegill (Lepomis macrochirus)

Several experiments were designed to determine the effects of sublethal cadmium exposure on ventilation rate and cough response of bluegill. Populations of test fish were selected to represent extremes in history of heavy metal exposures. Exposure to cadmium concentrations less than 1% of the reported median lethal threshold value produced significant increases in both ventilation frequency and cough rate. Changes in cough rates were directly proportional to the cadmium concentration. Cough response is an accurate short-term measure of chronic cadmium toxicity. There was good correlation between cadmium concentrations producing significant increases in cough rates and known MATC values. Based on acute toxicity studies and on changes in ventilation and cough rates, bluegill collected from a metal-contaminated lake did not exhibit increased tolerance to the toxic effects of cadmium.

Time dependent cadmium uptake by fathead minnows (Pimephales promelas) during field and laboratory exposure

Fathead minnows (Pimephales promelas) exposed to 2.5 ppb cadmium in an industrially contaminated lake accumulated whole body burdens of 3.19 ppm Cd in 12 hours, while minnows exposed to 48 ppb Cd in a continuous flow laboratory system did not reach comparable levels until the eighth day of exposure. Significant whole body accumulation of Cd (approximately 9 ppm) peaked within 17–20 days of exposure in the laboratory.

Cadmium and zinc in muscle of bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides) from an industrially contaminated lake

Abstract Cadmium and zinc analyses of 44 largemouth bass (Micropterus salmoides) and 29 bluegill (Lepomis macrochirus) indicate that fish in an ecosystem heavily contaminated by trace metals accumulate significantly more metal in edible muscle tissue than do fish in an uncontaminated ecosystem. Concentrations detected ranged from 0·010 to 1·308 ppm Cd and 18·2 to 158·2 ppm Zn (dry weight). Bluegill contained significantly greater concentrations of Cd and Zn than did bass and small bass contained significantly more Cd than did large bass. Human consumption of these fish is probably not a health hazard unless such fish constitute a major portion of the diet.

Changes in phosphorus concentrations in a eutrophic lake as a result of macrophyte-kill following herbicide application

Phosphorus (P) concentrations in water and sediment of a highly eutrophic lake were monitored before and after application of diquat to control the macrophyte Potamogeton crispus. Only a relatively small and short-term increase in P concentration in water occurred shortly after plant die-off resulting from herbicide application. Phosphorus concentrations in shallow water sediments decreased during the summer, and those in deep water sediments increased. Although a large increase in P concentration in the water occurred in late summer, it was not attributed to diquat. No major secondary effects of herbicide application were found during this study.