Duane A. Benoit

Toxic effects of cadmium on three generations of brook trout (Salvelinus fontinalis)

Abstract Three generations of brook trout (Salvelinus fontinalis) were exposed to several concentrations of total cadmium (0.06–6.4 μg Cd/liter). Significant numbers of first- and second-generation adult males died during spawning at 3.4 μg Cd/liter. This concentration also significantly retarded growth of juvenile second- and third-generation offspring. The maximum acceptable toxicant concentration (MATC) for brook trout exposed to cadmium in Lake Superior water (hardness 44 mg/liter as CaCO 3, pH 7–8) lies between 1.7 and 3.4 μg Cd/liter. Cadmium-residue analyses of kidney, liver, gill, gonad, spleen, muscle, and red blood cells frown first- and second- generation trout indicated that kidney, liver, and gill tissue accumulated the greatest amounts of cadmium at each water exposure concentration. No significant increases in cadmium were measured in edible muscle at any of the cadmium water concentrations tested. Cadmium residues in kidney, liver, and gill tissue of fish frown all exposure concentrations ...

A continuous-flow mini-diluter system for toxicity testing

Abstract A space saving portable mini-diluter exposure system for testing early life stages of fish and invertebrates has been developed and successfully used both in the laboratory and on-site with single chemicals and with complex effluents. This gravity-operated system can also be installed in a compact, vented enclosure to permit safe testing of hazardous volatile chemicals. The mini-diluter test system has several additional advantages over other widely used dosing systems in that it: (1) uses small volumes of complex effluents and/or single chemicals which reduces the problem of removing hazardous material from the test systems waste water; (2) works well with waste containing suspended solids; and (3) can maintain normal operation for up to 10 h if the effluent headbox supply pump fails and up to 4 h if the diluent water headbox supply pump fails.

Development and evaluation of test methods for benthic invertebrates and sediments: Effects of flow rate and feeding on water quality and exposure conditions

In order to ensure among-laboratory comparability in the results of sediment toxicity tests, it is necessary to characterize the influence of variations in test regimes on organism responses and exposure conditions. The objective of these studies was to develop and document an optimized combination of overlying water renewal (flow) and feeding rates for sediment tests with three commonly used benthic species (midges, Chironomus tentans; amphipods, Hyalella azteca; oligochaetes, Lumbriculus variegatus). Optimal conditions were defined by a number of chemical and biological considerations including: (1) flow rate through the system, (2) amount of food added, (3) acceptable responses (survival, growth, reproduction) of the organisms over the course of a 10-day test, and (4) maintenance of an adequate concentration of dissolved oxygen in overlying water. The goal was to minimize factors (1) and (2), while maximizing criteria (3) and (4). The major reason for minimizing (1) and (2) was the concern that excessive water flow or addition of food could reduce exposure of the test organisms to sediment-associated contaminants. To evaluate this, interstitial (pore) water concentrations of contaminants (ammonia, zinc, copper, dieldrin) were measured over the course of 10 day tests conducted with a number of different sediments under various flow and feeding regimes. The different combinations of flow/feeding had variable effects upon pore water concentrations of contaminants; for example under our optimized regime, in some instances slight decreases in interstitial water contaminant concentrations were observed, whereas in other cases contaminant concentrations remained constant or even increased. Overall, the use of minimal water renewal and feeding rates should result only in small changes in exposure of benthic organisms to contaminants in pore water over the course of 10-day tests.

Seasonal variation of acid volatile sulfide concentration in sediment cores from three northeastern Minnesota lakes

Acid volatile sulfide (AVS) is a natural agent in sediments which complexes some cationic metals and thereby influences the toxicity of these metals to benthic organisms. Because of its influence on metal bioavailability, AVS has been proposed as a key normalization phase for the development of sediment quality criteria for metals. However, studies conducted primarily in marine and estuarine systems have shown that AVS concentrations can vary markedly both temporally and with (sediment) depth. In this study, AVS concentrations were measured monthly for 16 mo in several segments of sediment cores from three freshwater lakes: Caribou Lake, Fish Lake and Pike Lake in northeastern Minnesota, USA. The concentrations of AVS in cores from the three lakes varied inversely with sediment depth. AVS concentrations also varied seasonally by as much as two orders of magnitude and were directly correlated with changes in water temperature. The correlation between AVS and temperature likely was related both to changes in primary productivity and sediment microbial activity.

Long-Term Effects of Zinc Exposures on Brook Trout (Salvelinus fontinalis)

Abstract Exposure of three generations of brook trout (Salvelinus fontinalis) to zinc concentrations ranging from 2.6 to 534 μg/liter produced no significant harmful effects. During a separate exposure of embryos and larvae, 1,368 μg Zn/liter significantly reduced (P = 0.05) both embryo and 12-week larval survival. An additional partial chronic exposure also resulted in significantly reduced (P = 0.05) egg chorion strength and embryo survival at 1,360 μg Zn/liter. The maximum acceptable toxicant concentration (MATC) for brook trout exposed to zinc in Lake Superior water (hardness = 45.4 mg/liter as CaCO3; pH = 7.0–7.7) lies between 534 and 1,360 μg Zn/liter. The 96-hour LC50 (median lethal) concentration for brook trout was 2,000 μg Zn/liter; thus the application factor (MATC/96-hour LC50) lies between 0.267 and 0.680. Brook trout gill, liver, kidney, and opercular bone tissues accumulated the greatest amounts of zinc. Edible muscle tissue did not accumulate zinc. Zinc loss from gill and liver from first-...

A SEDIMENT TESTING INTERMITTENT RENEWAL SYSTEM FOR THE AUTOMATED RENEWAL OF OVERLYING WATER IN TOXICITY TESTS WITH CONTAMINATED SEDIMENTS

A sediment testing intermittent renewal (STIR) system (stationary or portable) for invertebrate toxicity testing with contaminated sediments has been successfully developed and thoroughly tested at ERL-Duluth. Both the stationary and portable systems enable the maintenance of acceptable water quality (e.g. DO) through the capability of automatically renewing overlying water in sediment tests at rates ranging from 1 to 21 volume renewals/day. The STIR system not only significantly reduces the labor associated with renewal of overlying water but also affords a gentle exchange of water that results in virtually no sediment resuspension. Both systems can also be installed in a compact vented enclosure to permit safe testing of hazardous contaminated sediments. To date the STIR system has been used extensively for conducting 10-day bulk sediment tests with Chironomus tentans, Hyalella azteca and Lumbriculus variegatus.

Toxic effects of hexavalent chromium on brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri)

Abstract Exposing brook trout to various concentrations of chromium [Cr(VI)] for up to 22 months (including reproduction) significantly increased alevin mortality at 0.35 mg Cr l−1 and retarded growth of young brook trout at the lowest concentration tested (0.01 mg Cr l−1). Eight month exposures of rainbow trout significantly increased alevin mortality at 0.34 mg Cr l−1 and also retarded growth at the lowest concentration tested (0.10 mg Cr l−1). Exposures of brook trout lasting 22 months showed, however, that growth was only temporarily affected, and therefore, it was not used as an end point to measure the affects of chromium on either species. Reproduction, and embryo hatchability of brook trout were unaffected at Cr(VI) concentrations that affected survival of newly hatched alevins. The maximum acceptable toxicant concentration (MATC) for brook and rainbow trout exposed to Cr(VI) in water with a hardness of 45 mg l−1 (as CaCO3) and a pH range of 7–8 lies between 0.20 and 0.35 mg Cr l−1. The 96-h lc 50 for brook and rainbow trout was 59 and 69 mg Cr l−1, respectively: therefore, the application factor (MATC/96-h lc 50) for both species lies between 0.003 and 0.006.

A fathead minnow Pimephales promelas early life stage toxicity test method evaluation and exposure to four organic chemicals

Abstract A 32-day test was developed at the Environmental Research Laboratory—Duluth for conducting early life stage (ELS) toxicity tests with fathead minnows Pimephales promelas. These test procedures were evaluated by using the prescribed methods to establish estimated maximum acceptable toxicant concentrations (MATC) for fathead minnows exposed to four previously untested organic chemicals. Toxic effects on early developmental stages demonstrated that larval growth and survival were the most sensitive indicators of toxic stress. Embryo hatch and larval deformities at hatch were the least sensitive indicators of toxicity. The estimated MATCs for fathead minnows exposed to hexachlorobutadiene, 1,2-dichloropropane, 1,3-dichloropropane and 1,2-dichloroethane lie between 6·5 and 13 μg litre−1, 6 and 11 mg litre−1, 8 and 16 mg litre−1 and 29 and 59 mg litre−1, respectively. Results obtained from the four ELS test method evaluations and the estimated MATCs derived from these evaluations demonstrate the consistency of the ELS toxicity test procedures for fathead minnows currently being adopted as standards by the US Environmental Protection Agency and the American Society for Testing and Materials. These ELS test methods produced good replication and, when used to predict long-term chronic toxicity, will provide a rapid means to develop water quality criteria and screen large numbers of single chemicals or complex effluents.

Note a simplified flow-splitting chamber and siphon for proportional diluters

Abstract Simplified flow-splitting chambers and siphons were designed and tested for use with proportional diluters in bioassay systems. The apparatus allows each concentration from the diluter to be thoroughly mixed and divided four ways for delivery to duplicate fry and adult exposure tanks. Test water delivered to each exposure tank varied by only 5–10 per cent of the calculated volumes.

Acute and long-term effects of nine chemicals on the Japanese medaka (Oryzias latipes)

Ninety-six-hour acute and 28-day larval survival and growth tests were conducted with nine organic chemicals, using the Japanese medaka (Oryzias latipes) as the test organism. The nine tested chemicals were allyl isothiocyanate, aniline, benzyl acetate, 4-chloroaniline, 2-chloroethanol, 2,4-diaminotoluene, 1,2-dibromoethane, 2,4-dichlorophenoxyacetic acid (2,4-D), and phenol. The derived 96-h LC50 values for medaka for all chemicals ranged from 0.077 mg/L for allyl isothiocyanate to 2,780 mg/L for 2,4-D. The chronic values for six of the nine chemicals tested ranged from 0.013 mg/L for allyl isothiocyanate to 42.5 mg/L for 2,4-D. Acute-to-chronic ratios for these six chemicals ranged from 1.4 for 2-chloroethanol to 70.9 for 2,4-D. Growth of medaka was significantly reduced in the lowest exposure concentration during 28-day larval tests with aniline, 4-chloroaniline, and 2,4-diaminotoluene. The estimated maximum acceptable toxicant concentration was reported as less than the lowest exposure concentration of 4.6, 2.2 and 40.3 mg/L for tests with aniline, 4-chloroaniline and 2,4-diaminotoluene, respectively. Chronic values for 2-chloroethanol and medaka were 12.6 mg/L during an embryo-larval test and 22.1 mg/L during the 28-day larval test.