INTERIM REPORT TASK 002 ROAP 10CAR TOXICITY OF COPPER, CADMIUM AND ZINC TO PACIFIC NORTHWEST SALMONIDS Gary A. Chapman Western Fish Toxicology Station National Water Quality Laboratory 1350 S.E. Goodnight Avenue Corvallis, Oregon 97330 June 1975 NATIONAL ENVIRONMENTAL RESEARCH CENTER OFFICE OF RESEARCH AND DEVELOPMENT U.S. ENVIRONMENTAL PROTECTION AGENCY CORVALLIS, OREGON 97330 ------- INTERIM REPORT TASK 002 ROAP 10CAR TOXICITY OF COPPER, CADMIUM AND ZINC TO PACIFIC NORTHWEST SALMONIDS Gary A. Chapman Western Fish Toxicology Station National Water Quality Laboratory 1350 S.E. Goodnight Avenue Corvallis, Oregon 97330 June 1975 NATIONAL' ENVIRONMENTAL RESEARCH CENTER OFFICE OF RESEARCH AND DEVELOPMENT U.S. ENVIRONMENTAL PROTECTION AGENCY" CORVALLIS, OREGON 97330 ------- LIST OF TABLES Number I Water quality characteristics of dilution water for bioassays. II Ninety-six hour mortality data from static bioassays of coho salmon alevins and buttoned-up fry. Solutions were made up in Willamette River water and renewed every 24 hours. Bioassays were conducted at 10 C. Ill Mortality data from copper, cadmium, and zinc acute lethality tests with adult salmonids. IV LC50 values (yg/1) for cadmium to various life stages of salmonids. V LC50 values (ug/T) for zinc to various life stages Of salmonids. VI LC50 values (yg/1) for copper to various life stages of salmonids. VII Growth and mortality in 4 month, egg-through-fry, partial chronics with chinook salmon and cadmium, zinc, and copper. The cadmium, zinc, and copper bioassays were terminated after 12, 13, and 14 weeks post-hatch respectively. 2 ------- SECTION I INTRODUCTION Active and abandoned mining sites create heavy metal pollution problems in several areas in the Pacific Northwest (Sceva, 1973). Most notable pollution problems from these activities are acidity, copper, iron, zinc, manganese, and copper pollution. In addition, data for water quality criteria are being developed on numerous chemicals including copper, cadmium, and zinc, but little data are available on the salmonids of the Pacific Northwest. This report covers a series of 50 toxicity tests with heavy metals, primarily cadmium, copper and zinc, and their effects on selected species of salmon and trout native to the Pacific Northwest. The series began in February, 1971, and was completed in March, 1975. Forty-six of the tests were acute lethality tests lasting from 96 to 390 hours, and four tests were partial (less than full life cycle) chronic toxicity bioassays lasting from 19 weeks to 21 months. The studies can be split into five separate groups according to purpose: GROUP I: COHO SALMON STATIC ACUTE BIOASSAYS. These tests were conducted to find the approximate lethal threshold ranges for coho salmon (Oncorhynchus kisutch) for cadmium, copper, lead, and zinc. Data were collected for 96 hr. LC50 calculation, and changes in metal tolerance were followed closely through the early larval and juvenile stages. 3 ------- GROUP II: SOCKEYE SALMON ADULT THROUGH SMOLT PARTIAL CHRONIC BIOASSAY. This 21-month test was designed to determine the maximum allowable level of zinc for the sockeye salmon (Oncorhynchus nerka). GROUP III: ADULT SALMONID FLOW-THROUGH ACUTE BIOASSAYS. These tests were conducted to determine the levels of heavy metals acutely lethal to adult coho salmon (Oncorhynchus kistuch) and steel head trout (Salmo gairdneri), which because of their large size and relative inavailability, had never been bioassayed. GROUP IV: JUVENILE SALMONID FLOW-THROUGH ACUTE BIOASSAYS. This series of bioassays was designed to yield data on the relative sensitivity to metals of the various juvenile life stages of coho and chinook salmon and steelhead trout. Ninety-six hour, 200 hours, and longer LC50 values were calculated whenever possible. GROUP V: CHINOOK SALMON EGG-THROUGH-FRY PARTIAL CHRONIC BIOASSAYS. These tests were conducted to determine if continuous exposure to metals through the embryo, alevin and young fry stages would produce adverse effects at lower metal concentrations than those causing mortality in the acute bioassays. 4 ------- SECTION II METHODS CHEMICAL All bioassays were conducted with reagent grade chloride salts of the metals (CuCl2*2H£0; CdCl2"2 1/2H20; and ZnCl2)• Stock solution for static bioassays were mixed in distilled or deionized water, while stock-solutions for flow-through bioassays were mixed in diluent water. (Cadmium superstocks for dilution to make up flow- through cadmium stock solutions were also mixed in distilled or deionized water). Stock solutions were usually acidified with concentrated nitric acid to about pH 4. Six static bioassays (GROUP I) were conducted using Willamette River water for dilution. All other bioassays used Western Fish Toxicology Station (WrTS) well water for dilution. Both waters are characterized by low hardness and alkalinity. In some instances where the well water quality differed significantly from the norm, reverse osmosis treated well water was mixed with ambient well water to attain normal water quality using hardness as the index of normality. A summary of water quality values for the three diluent waters is listed in Table I. BIOLOGICAL All bioassays were conducted on marine anadromous salmonids native to the west coast of North America. Four species were used: 5 ------- TABLE I. Water quality characteristics of dilution water for bioassays Blend: . Well + Reverse Parameter Units Willamette WFTS Weill/ Osmosis Product Total Organic Carbon mg/1 3.4 l.a 1.4 pH 7.4 7.3 7.2 A1kalinity mg/1 23 24 22 Hardness mg/1 22 25 24 Nitrate mg/1 0.15 0.19 0.18 Ammonia mg/1 D.06 0.04 0.02 Calcium mg/1 5.5 6.8 6.1 Magnesium mg/1 2.1 1.8 1.8 Sodium mg/1 4.1 5.0 4.4 Potassium mg/1 0.8 0.6 0.4 Sulfate mg/1 6.6 4.2 5.8 Dissolved Solids mg/1 52 59 53 Suspended Solids mg/1 15 1.5 <1 Chloride mg/1 4 6 6 Cadmium yg/l <1 <1 <1 Chromium yg/1 <2 <2 <2 Cobalt yg/l <1 <2 <1 Copper yg/l 3.3 3.1 1.8 Iron yg/1 736 98 36 Lead yg/l 3.0 4.0 5.5 Manganese yg/i 30.7 3.5 2.2 Nickle yg/l 1.9 1.9 1.6 Zinc yg/l 9.4 4.8 4.0 Mercury yg/l 0.9 1.2 0.9 •I/Mean values excluding periods of fluctuating hardness and alkalinity. 6 ------- sockeye salmon, Oncorhynchus nerka; coho salmon, Oncorhynchus kisutch; Chinook salmon, Oncorhynchus tshawytscha; and steel head trout, Salmo qairdneri. Adult salmonids were guided into traps or ponds by water flow, individually brail led into a refrigerated fish hauling truck, and transported to the WFTS test facility. Adult coho salmon and steelhead trout were taken at the end of their spawning migrations at the Fall Creek and North Fork Hatcheries respectively, on the Alsea River in western Oregon. Sockeye salmon adults were collected during their spawning migration at Bonneville Dam on the Columbia.River. All non-adult fish were reared at the WFTS test facility from eggs obtained from state fish hatcheries in Oregon. Coho salmon eggs were obtained from the Fall Creek Hatchery, steelhead trout eggs from the North Fork Alsea Hatchery, and chinook salmon eggs from the Willamette Hatchery. Iodophore disinfectant (Wescodyne or Betadyne) has been used at WFTS since 1973 for prophylactic treatment of eggs brought into the laboratory. Solutions of 1:600 to 1:150 have been employed for from 5 to 15 minutes as a dip-bath treatment. The pH of the solutions was adjusted to pH 7 by the addition of sodium bicarbonate. Egg disinfection was the only treatment given any of the fish used in the bioassays. Juvenile fish were fed a commercial diet (usually Oregon Moist Pellet) except for 48 hours prior to and during acute lethality bioassays. All partial chronic test juveniles were fed an OMP ration based on fish number, disregarding growth differences between treatments. 7 ------- APPARATUS AND DESIGN Coho salmon static lethality tests (group I) were conducted in 3 liters of water in 1 gallon jars. Solutions were maintained at 10 C, aerated continuously, and renewed every 24 hours. Two jars were prepared at each metal concentration and 5 fish were placed in each jar. Loading factors increased from 0.27 to 1.15 g/1 during the series of tests. All adult salmon tests were conducted in a series of 5 tanks 3.67 m in diameter and 0.9 m deep. Tank volume was maintained at 5250 liters with a flow rate of 19 liters per minute and a recycle rate of 150 1/min. Adult tests were conducted at 10 t 2 C. Loading factors were from 5 to 17 g/1. Twenty adult sockeye were held at each zinc concentration during the initial phase of the partial chronic bioassay (group II). Eggs from 5 females per concentration were used as the source of fish for the juvenile phase of this bioassay. After hatching, the eggs from a common treatment were pooled and 400 fry (200 fry per duplicate aquarium) were exposed to each zinc concentration. During the adult salmonid acute lethality test series (group III) the number of test fish per tank varied. The minimum was 10 fish per concen~ tration. The maximum was 33 fish per concentration. Egg and juvenile test chambers were dosed by continuous flow diluters with flow rates of 500 ml/min/aquarium except for smolt 8 ------- tests which had 1.5 1/min/aquarium flow rates. Eggs were incubated in small incubator chambers, juveniles were exposed in 19 liter aquaria, and smolts were exposed in 100 liter aquaria. Loading factors ranged from 0.2 g/1 to 14.6 g/1 and mean temperatures were 12 t 1 C. All group IY juvenile acute lethality tests utilized 40 fish per concentration (20 fish per duplicate aquarium). The egg through fry partial chronic bioassays (group V) were started with about 200 eggs (100 eggs per duplicate incubator). With the above loading factors, flow rates, and chamber volumes, mean dissolved oxygen concentrations never fell below 8.8 mg/1 in any chamber, aquarium, or tank. 9 ------- SECTION III RESULTS GROUP I: COHO SALMON STATIC TESTS The most definitive data were collected in a series of six weekly 96 hr. lethality tests of Cd, Cu, Pb, and Zn using coho salmon from two weeks post-hatch through seven weeks post-hatch. Dilution water was coarse-filtered Willamette River water. Results of these bioassays indicated that 96 hr. LC50's could be expected at concentrations near 45 ppb with copper, 200 ppb with zinc, 600 ppb with lead, and 2 ppb with cadmium (Table-II).¦ The susceptibility of the fish to copper, zinc, and lead did not vary appreciably with age, but the susceptibility to cadmium increased significantly as the fish developed from two week old alevins to seven week old fry during the series of bioassays. GROUP II: SOCKEYE SALMON PARTIAL CHRONIC TEST A 22-month, adult-through-smolt, partial chronic bioassay was begun in July 1971 with the completion of the adult test facility at the Western Fish Toxicology Station. Sockeye salmon were chosen as the test organism because of their relatively long freshwater residence as prespawning adults (4 to 5 months), their relatively small size, and their availability. Test exposure concentrations were based on the available data from juvenile coho and chinook salmon. Zinc concentrations of 30, 60, 90, and 120 ppb were selected as exposure levels. 10 ------- Table II. N1nety-s1x hour mortality data from static bloassays of coho salmon alevlns and buttoned-up fry. Solutions were made up 1n Willamette River water and renewed every 24 hours. Bloassays were conducted at 10 C. Date 1000 300 100 60 Cu (ppb) 45 30 10 Developmental"^ Index 'F1sh Wet Wt. (nig) 02/02/71 100 100 100 0 0 43.8 159 02/08/71 — 100 100 80 0 0 61.8 225 02/15/71 — ... 100 60 20 0 0 75.0 328 02/22/71 — — 100 60 70 0 0 83.5 375 03/01/71 — ¦ — 100 70 10 0 0 (100) 474 03/08/71 100 80 60 10 0 (100) 486 Zn (ppb) Date 30,000 10,000 3,000 1,000 600 400 300 200 140 100 60 02/02/71 02/08/71 02/15/71 02/22/71 03/01/71 03/08/71 100 100 100 100 80 100 100 90 100 100 10 90 60 80 100 100 50 50 80 80 30 0 0 0 40 0 Pb (ppb) Date 30,000 10,000 6,000 3,000 1,000 600 300 100 60 02/02/71 100 100 90 90 0 _ — —' 02/08/71 100 100 100 60 100 ¦ — 02/15/71 — — 80 10 0 0 0 02/22/71 — 70 60 40 0 0 — 03/01/71 — — 100 100 60 10 0 — 03/08/71 — — 100 100 50 20 0 Cd (ppb) Date 3,000 1,000 300 TOO 30 15 10 6 4.5 3 2 1 0.5 02/02/71 — 20 ... 10 30 ... 40 ... ... ... 02/08/71 100 100 100 100 100 — — — .— . —. . ... 02/15/71 100 ... 100 100 100 100 30 — ' .— 02/22/71 100 — — — 100 90 70 50 10 03/01/71 100 — — — — — 100. 100 100 100 — 0 ... 03/08/71 — — — — — — 100 100 100 90 10 0 1/ Index of development of alevlns Is the percent of total alevin weight which 1s not yolV. This is calculated: Index = fish weight w/o yolk weight of fish plus yolk X 100 11 ------- No effects were observed through egg-take in October, so one additional concentration (240 ppb) was employed throughout the remainder of the bioassay, (i.e. eggs from control fish were subsequently reared through the smolt stage at 240 ppb zinc). The adult-to-smolt bioassay was concluded in April 1973, when smolts from each zinc concentration were successfully held for 96 hours in 30 ppt seawater. No adverse effect of zinc exposure was noted during the 22 month test. The following parameters were measured for effect and yielded "no effect" results: adult mortality; fecundity; spawning time; hatchability; growth; embryo, alevin, parr and smolt mortality; and ability to survive transfer to 30 ppt seawater. About mid-way through the bioassay, an acute lethality flow-through test was conducted to determine if acclimation to zinc may have occurred and to check the 96 hr. LC50 of control juvenile sockeye. The results indicated that the 96 hr. LC50 for 9 month old juvenile sockeye'was about 740 ppb, a concentration at which all the 240 ppb acclimated juveniles survived. The data produced from this adult-to-smolt bioassay do not allow the determination of either a Maximum Allowable Toxicant Concentration (MATC) or an application factor relating the 96 hr. LC50 with the MATC. However, the application factor shown to be "safe" from the adult-to- smolt exposure is ^ 120/740 or 0.16; that based on egg-to-smolt exposure 12 ------- is > 240/740 or 0.32. Thus, zinc concentrations of about 0.2 of the 96 hr. LC50 appear to be safe for spawning and rearing sockeye salmon, however no application factor is derivable for an effect or unsafe level because chronic exposure levels of zinc were too low to produce an effect. GROUP III: ADULT SALMONID ACUTE LETHALITY TESTS The acute lethalities of cadmium, copper, and zinc were determined for adult coho salmon and steelhead trout in a series of bioassays from November, 1971 through February, 1972 (Table III). Fluctuations in hardness and alkalinity occurred during the series of bioassays and made direct comparisons between bioassays impossible. GROUP IV: JUVENILE SALMONID ACUTE: LETHALITY TESTS Full life cycle chronic bioassays with copper and zinc have indicated that the effect of copper on brook trout (Salvelinus fontinalis) appears most severe during the very young juvenile stages (McKim and Benoit, 1971) and that the effect of zinc is manifested by poor reproductive success in fathead minnows (Brungs, 1969). Since zinc was shown to have no discernible adult-to-smolt effect at 0.16 of the 96 hr. LC50 (as opposed to an application factor of at least 0.01 in the fathead minnow), I decided to concentrate on the acute lethality of metals to the various freshwater life stages of salmonids. 13 ------- TABLE III. Mortality data from copper, cadmium, and zinc acute lethality tests with adult salmonids. Species Exposure Period Steel head Trout n A1kalinity copper 11 25-45 cadmium 12 25-62 zinc 11 45-59 zinc 11 37-55 96 hr. 57 ppb 1400-2000 ppb <1265 ppb 400 hr. 5 ppb Coho Salmon copper cadmi um zinc^ n 33 20 10 A1 kalinity 22 22 25 96 hr. 43 ppb 17 ppb 1250 ppb 200 hr. 3 ppb y Static bioassay with recirculation for aeration. 14 ------- Due to limitations of time and space the study was confined mainly to two species, the chinook.salmon and the steelhead trout. The coho salmon was de-emphasized as it inhabits mainly small coastal streams away from existing population centers and pollution sources. The sockeye salmon was eliminated from this phase of the study due to evidence that it is more resistant to metal toxicity than other salmonids. Flow-through lethality tests were conducted on newly hatched alevins, swim-ups, parr, and smolts of steelhead trout and chinook salmon with cadmium, copper, and zinc. Each test required up to 3 weeks, including a one-week, post-handling acclimitization period for fish in the test aquaria prior to metal introduction. The series of tests was begun August 1972 and concluded August 1974, although no tests were conducted between January 1973 and March 1974 because of inability to control fluctuating hardness and alkalinity in ambient well water. The completion of a system to variably blend osmosis treated well water with ambient well water made it possible to complete the series after March 1974. The mortality data from these tests are included in Tables IV, V, and VI. The 200-hour LC50's for steelhead and chinook (excluding the more resistant alevins) were 0.9 to 2.3 ppb for Cd, 93 to 395 ppb for Zn, and 14.7 to 26 ppb for Cu. 15 ------- TABLE IV. LC50 values (yg/1) for cadmium to various life stages of salmonids. Species Stage (Age)l^ 96-hr. Time 200-hr. Terminal^ Steel head Parr (5 mo.) 1.0 0.9 0.9 (390 hr) Steel head Swim-ups (4 wk.) 1.3 1.3 1.3 (216 hr) Chinook Parr (6 mo.) 3.5 2.0 1.4 (339 hr) Chinook Swim-ups (3 wk.) 1.8 1.6 1.5 (264 hr) Chinook Smolts (18 mo.) >2.9 2.3 1.4 (339 hr) Steel head Smolts (13 mo.) 4.1 1.5 1.5 (339 hr) Co ho Parr (6 mo.) 2.7 -*•- 2.0 (225 hr) Coho Adults 17.5 3.3 Steel head Adults •» ^ 4.8 (408 hr) Chinook Alevins (1 day) >26.3, >26.3 >26.3 (261 hr) Steel head Alevins (1 day) >27.0 >27.0 (186 hr) i/Age (from hatch) at start of test. 2/LC50 value at the time that the test was terminated. 16 ------- TABLE V. LC50 values (yg/1) for zinc to various life stages of salmonids. Species Staqe (Aqe)-^ 96-hr. 200-hr. Terminal-^ Steel head Swim-ups (4 wk.) 93 93 93 (216 hr) Chinook Swim-ups (3 wk.) 97 97 95 (264.hr) Steel head Parr (5 mo.) 136 120 120 (344 hr) Steel head Smolts (13 mo.) >651 278 278 (339 hr) Chinook Smolts (18 mo.) 701 369 306 (369 hr) Chinook Parr (6 mo.) 463 395 374 (276 hr) Steel head Alevins (1 day) 815 — 555 (186 hr) Chinook Alevins (1 day) >661 >661 >661 (214 hr) Co ho Parr (6 mo.) >1232 1058 (217 hr) .1/ Age (from hatch) at start of test. if LC50 value at the time that the test was terminated. 17 ------- TABLE VI. LC50 values (yg/1) for copper to various life stages of salmonids. Species Staqe (Aqe)^ 96-hr. 200-hr. Terminal 2/ Steel head Parr (5 mo.) 18.0 14.7 13.8 (387 hr) Steel head Swim-ups (4 wk.) 17.1 16.6 — Steel head Smolts (13 mo.) >26.0 21.4 18.4 (339 hr) Chinook Swim-ups (3 wk.) 19.1 18.7 18.7 (264 hr) Chinook Alevins (1 day) 26.4 20.4 19.7 (235 hr) Chinook Parr (6 mo.) 38.0 29.8 21.6 (276 hr) Chinook Smolts (18 mo.) 26.0 26.0 22.0 (339 hr) Steel head Alevins (1 day) 28.2 — 25.8 (186 hr) Co ho Parr (6 mo.) 28.0-38.0 28.0-38.0 (217 hr) Co ho Adults 42.9 — — Steel head Adu]ts 57.4 ^ « ... y Age (from hatch) at start of test. y LC50 value at the time that the test was terminated. 18 ------- GROUP V: EGG-TO-FRY PARTIAL CHRONIC TESTS. The finding of acute mortality of swim-up and parr salmonids at very low levels of Cd, Cu, and Zn raised the question of whether longer-term exposure of very young stages of these fish would produce adverse effects at even lower levels of these metals. Accordingly, a series of 3, egg-through-fry 4-month partial chronic tests were conducted on Chinook salmon, one test each with Cd, Cu.and Zn. Exposure was continuous from several hours post-fertilization through hatch, swim-up and feeding fry stages. Mortality in these 3 bioassays is summarized in Table VII. Significant mortality occurred with all 3 metals, but even though the highest test concentrations of each metal exceeded the 200 hr. LC50's for chinook parr and/or swim-ups, only-the, 20. ppb Cu concen^ tration produced greater than 50 percent mortality. Neither 0.96 ppb cadmium nor 272 ppb zinc produced adverse effects during the four month egg-to-fry partial chronic, even though these concentrations were near the 200 hr. LC50 value observed in acute lethality tests. Only copper, which produced significant mortality at 15.5 ppb and 11.7 ppb appeared to produce adverse effects at levels below 200 hr. LC50 values. The effect of cadmium and zinc on growth were small, and indicated that the metal exposed fish grew as well as or better than control fish. Copper caused very much lower growth rates at all concentrations 19 ------- TABLE VII. Growth ami mortality in 4 month, egg-through-fry, partial chronics with chlnook salmon and cadmium, zinc, and copper. The cadmium, zinc, and copper bioassays were terminated after 12, 13, and 14 weeks post-hatch respectively. Cadmium Concentration (pg/1) Nominal I s 2.0 1.88 0.29 1.34 1.30 0.22 0.9 0.96 0.18 0.6 0.71 0.13 0.4 0.51 0.13 Control 0.16 0.11 Z1nc Concentration (pg/1) Nominal X S 500 511 20 280 272 11 157 173 10 88 101 15 49 60 7 Control 9 6 Copper Concentration (yg/1) Nominal J s 20 20.2 1.8 15 *5.5 0.8 11.25 H.7 0.8 8.4 9.4 1.0 6.3 7.4 1.0 Control 1.2 1.7 Mortality (X) Mean Dry Weight (mg) 27 140 18 131 3 162 6 159 5 127 9 127 Mortality (%) Mean Dry Weight (mg) 22 143 11 167 13 163 4 175 9 202 9 141 Mortality (2) Mean Dry Weight (mg) 94 41 49 63 20 99 10 91 10 113 9 177 20 ------- tested. A similar effect was reported by McKim and Benoit (1971), where copper levels down to 3.4 ppb reduced growth of brook trout for up to 23 weeks post-hatch, however the growth rate of copper intoxicated fish was the same as control fish after 23 weeks. A similar recovery could have occurred in the chinook bioassay had it been continued longer. 21 ------- SECTION IV SUMMARY ZINC Exposure of salmonids, especially post-swim up juveniles, to zinc concentrations as low as 93 ppb produced 50 percent mortality in 96 hours. Extending the exposure period longer (up to 344 hours exposure) didn't produce appreciably greater mortality. Steel head trout appeared to be the most susceptible species tested, followed by Chinook salmon, coho salmon and sockeye salmon, although data on the latter two species were not as complete. Partial chronic exposures to zinc produced no evidence of effect levels below those seen in acute flow-through tests. In fact, effect levels in Chinook egg through fry tests, (4 month) were three to five times higher than 96 hr. LC50 concentrations for Chinook swim-ups, indicating that significant acclimation to zinc occurred. No effect was seen in adult through smolt partial chronic tests at a high concentration of 120 ppb, or in egg-thru-smolt partial chronic tests at a high concentration of 240 ppb. These presumably safe concentrations would, when coupled with the 740 ppb 96 hr LC50 for sockeye fry, result in application factors for "safe" levels of zinc of not less than 0.16 for adult thru smolt exposure and not less than 0.32 for egg thru smolt exposure. 22 ------- Concentrations below the 96 hr. LC50 produced mortality in the acute exposure tests; 20 percent mortality occurred at 67 ppb with steelhead swim-ups and 10 percent mortality was seen at 63 ppb with chinook swim-ups. Acclimation to zinc accounts for the higher "no effect" levels seen in partial chronic exposures. Recent communications from NWQL (McKim, personal communication) revealed similar acclimation of brook trout to zinc, and showed no effect of 500 ppb Zn on reproduction in brook trout. Thus, the 0.01-0r-so application factor for Zn, derived from fathead minnow reproduction effects, appears to have little relation to salmonids. Lorz (personal communication!/) has shown that Zn has little effect on saltwater adaptation of salmonids following acute exposure to zinc. It therefore appears that the acute toxicity tests reported here represent a surprisingly sensitive direct estimator of safe and unsafe levels of zinc. COPPER Acute lethality tests with copper produced 96 hr. LC50 values as low as 18 ppb and 200 hr. LC50 values as low as 14.7 ppb (with steelhead trout swim-upsjL Appreciable mortality, 33 and 18 percent, occurred at 13.8 and 11.5 ppb respectively. Other stages of steelhead trout and chinook salmon had 200 hr. LC50 values between 16.6 and 29.8 ppb. Dr. Harry Lorz, Oregon State Wildlife Commission, Research Division, Corvallis, Oregon 97330. 23 ------- Egg thru fry partial chronic bioassays produced 20 percent mortality at 11.7 ppb in 5 months. According to McKim and Benoit (1971) alevin-juvenile mortality was the most sensitive life stage in brook trout, regardless of previous parental or embryonic exposure. However, the bulk of the mortality occurred between 3 and 11 months post-hatch. The lowest effect level in their study (17.4 ppb) produced double the control mortality at three months post-hatch. A similar mortality (20 percent Vs. 9 percent in controls) at 3 1/2 months post-hatch occurred at 11.7 ppb in my chinook egg-to-fry partial chronic. The effect and no-effect concentrations in the chinook egg thru fry partial chronic were 11.7 ppb and 9.4 ppb respectively, and the 96 hr. LC50 for chinook swim-ups (most sensitive stage) was 19.1 ppb. Therefore the apparent application factors would be 11.7/19.1 and 9.4/19.1 or 0.61 and 0.49 respectively for the effect and no effect levels. These levels (11.7 and 9.4 ppb) are very close to what would be predicted from the acute toxicity bioassay with chinook swim-ups (18 percent mortality at 11.5 ppb). CADMIUM Cadmium concentrations as low as 0.9 ppb can produce 50 percent mortality in acute toxicity bioassays (200 hr. LC50 for steel head parr). Ten percent mortality occurred at 0.65 ppb. These are the 24 ------- lowest cadmium effect levels measured In studies at WFTS. Chronic egg-thru-fry exposure indicates that acclimation occurs and this implies that unless reproductive or smoltification problems can be shown at sub-acute levels, there is little liklihood for direct effect levels below these acutely lethal concentrations. GENERAL There is little doubt that the acute toxicity bioassay tests conducted on metals at WFTS were very sensitive with respect to estimating safe levels. None of the partial chronic tests (which were far fewer than the acutes) yielded evidence of a large application factor and supposably "safe" levels could be estimated fairly well at the highest no kill concentration from the acute lethality tests. These results seem atypical with respect to much of the heavy metal data developed at other NWQL laboratories. However, on closer examination, the smaller application factors derived at WFTS, coupled with the lower LC50's, produce effect and no-effect levels for these metals which are similar to other NWQL data. This is especially true with the brook trout data of McKim and Benoit (1971) which show unsafe and safe levels of copper at 9.5 yg/1 and 17.4 yg/1 respectively (ours are 9.4 yg/1 and 11.7 yg/1). Much of the variability in LC50 and application factor data probably derives from the effect of metal complex formation. Natural 25 ------- waters of distinctly different chemical composition will yield different proportions and types of metal forms. Metal uptake rates will therefore vary and this will affect LC50 concentrations. This factor alone could produce different application factors. Some forms of a metal may have significant long term toxic effect but have little acute lethal effect (or visa-versa). In addition, intra- and inter-specific fish variability may also affect the application factor. Considering all these phenomona it is surprising how well the bioassay data compare. Further research is planned to compare lethal levels of metals in the field and laboratory, especially with respect to free cation to total metal ratios. In addition, the Cu and Cd complexing capacity of various natural waters will be investigated to ascertain the variability and predictability of metal complexing. 26 ------- BIBLIOGRAPHY Brungs, William A. 1969. Chronic toxicity of zinc to the fathead minnow Pimephales promelas Rafinesque. Trans. Am. Fish. Soc., 98(2J: 272-2797^ McKim, J. M., and D. A. Benoit. 1971. Effects of long term exposures to copper on survival, growth, and reproduction of brook trout (Salvelinus foritinalis). J. Fish. Res. Bd. Canada 28; 655-662. Sceva, Jack E. 1973. Water quality considerations for the metal mining industry in the Pacific Northwest. E.P.A. Region X, Report No. Region X-3, 69 pp. 27 ------- |