Gulf toadfish (Opsanus beta) were continuously exposed as embryos, sac fry, and juveniles to technical chlorpyrifos in two 49-day early life-stage toxicity tests. Survival was significantly (α = 0.05) reduced only in 150 μg/liter. However, toadfish exposed to chlorpyrifos concentrations from 3.7 to 150 μg/liter weighed significantly less than control fish: 9% lower in 3.7 μg/liter to 62% lower in 150 μg/liter. The 96-hr LC50 for juvenile fish was 520 μg/liter. Concentrations of chlorpyrifos in toadfish and bioconcentration factors increased with increasing exposure concentration, a condition not generally observed with other marine fishes and other test chemicals. These results demonstrated the procedures for, and the practicality of, early life-stage tests with this marine species. We recommend the use of the gulf toadfish for comparative toxicity testing and for evaluating the toxicity of substances in conjunction with ontogenetical, physiological, and histological investigations of this considerably studied genus. We do not recommend it for routine effects testing.

California grunion were continuously exposed as embryos and fry to technical chlorpyrifos in two toxicity tests conducted in the same exposure apparatus. The first test, a 35-day early life-stage (ELS) test, began with approximately 2.5-day-old embryos that were exposed in flow-through aquaria in darkness until hatching was stimulated on Day 9 of exposure. The second toxicity test, a fry test, began with newly hatched fry and lasted 26 days. Test water temperature ranged from 23 to 26°C and salinity from 24.5 to 34.0%.. Results of the two tests were similar, indicating that exposure of embryos added little to the overall toxicity of chlorpyrifos to grunions. Percentage hatch of embryos was unaffected by the chlorpyrifos concentrations tested. Fry survival was apparently reduced in nominal concentrations ⩾ 1.0 μg/liter in both tests, but significantly so in concentrations ⩾ 1.0 μg/liter in the ELS test and ⩾2.0 μg/liter in the fry test. When compared with carrier controls, mean fish weights were significantly reduced in nominal chlorpyrifos concentrations ⩾ 0.5 μg/liter in the ELS test and ⩾1.0 μg/liter in the fry exposure. Mean bioconcentration factors were 770× for fish that survived the ELS test and 190× for those that survived the fry test. Results demonstrate the practicality of conducting ELS tests for the first time with a marine fish from the Pacific coastal waters of the United States.

Swimming performance of the estuarine sheepshead minnow, Cyprinodon variegatus, was measured in a stamina tunnel at the end of life-cycle toxicity tests with the organophosphate pesticides EPN (265 days) and Guthion (219 days). Effects of acetylcholinesterase (AChE) inhibition were also determined. These measures were compared to survival, growth and reproduction data obtained in the life-cycle toxicity test. Significant effects on swimming stamina were detected in fish exposed to 2.2 μg EPN/1 (57% that of control fish) and in fish exposed to 4.1 μgEPN/1 (46% of controls). Survival and growth were reduced only in 7.9 μg EPN/1. Swimming performance was not affected by Guthion concentrations up to 0.5 μg/1, a concentration affecting reproduction. AChE was significantly inhibited by all tested concentrations of EPN, 0.25 to 7.9 μg/1, and Guthion, 0.06 to 0.50 μg/1. Swimming stamina may be an important endpoint to include with measurements of effects on survival, growth and reproduction in chronic toxicity tests with fish, but the relation of AChE inhibition to these endpoints is uncertain.

The effect of substances on the development of estuarine communities was assessed by comparing the numbers, species, and phyla of benthic animals that grew from planktonic larvae in an uncontaminated apparatus and in three identical apparatuses continuously contaminated (each with a different concentration) for 2 to 4 months. Each apparatus was separated into ten sand-filled compartments (40 total) and received a continuous flow of seawater containing natural plankton. We conducted six experiments, using Aroclor 1254, toxaphene, pentachlorophenol, Dowicide G-ST, barite, and a lignosulfonate drilling mud. The communities that developed during each test were diverse, averaging more than 4000 individuals, 50 species, and 7 phyla. Comparison of the results of these tests with results of acute and chronic exposures of single species demonstrates that: (a) the test can be as sensitive or more sensitive than chronic exposures of single species because the often more sensitive early developmental stages are exposed; and (b) the species typically impacted are representatives of phyla that are also sensitive in single-species tests. Also, the test may identify sensitive species not normally tested, thereby helping us to select species for additional toxicity tests. The test can also assess impacts of substances that affect community structure by physically altering the substrate.

Abstract. Sheepshead minnows, Cyprinodon variegatus Lacépède, exposed to 5.5 to 31 μg/1 of the herbicide trifluralin, throughout their first 28 days of life, developed a heretofore undescribed vertebral dysplasia. This dysplasia consisted of semi‐symmetrical hypertrophy of vertebrae (three to 20 times normal), characterized by foci of osteoblast and fibroblasts actively laying down bone and bone precursors. Effects of the abnormal vertebral development were dorsal vertebral growth into the neural canal, ventral compression of renal ducts, and longitudinal fusion of vertebrae. Pish, exposed for 51 days to 16.6 μg/1 trifluralin and thereafter depurated for 41 days, showed no increase in vertebral dysplasia during depuration; however, residual spinal column damage was evident. Serum calcium concentrations were elevated in adult fish exposed for 4 days to 16.6 μg/1 trifluralin. Fluorosis or mimicry of hypervitaminosis A are considered possible mechanisms for the osseous effect, but are not considered to be the only possible causes. The highly predictable nature of this disorder in experimental exposures strengthens the probability that young fish may serve as experimental models for determining effects of chemicals on early vertebrate ontogeny, particularly in regard to skeletal development.

We investigated the toxicity of Diazinon to sheepshead minnows continuously exposed in flow-through toxicity tests. In the 96-hour acute test, a measured concentration of 1,400/ μg/liter was lethal to 50% of the juvenile test animals. In the partial life-cycle test, we also investigated uptake of Diazinon by sheepshead minnows and effect of Diazinon on brain acetylcholinesterase (AChE) activity. Average measured concentrations in the partial life-cycle test were nondetectable (control), 0.47, 0.98, 1.8, 3.5, and 6.5 μg of Diazinon per liter of seawater. Although the number of eggs spawned by continuously exposed fish was significantly reduced (α = 0.05) in all concentrations, no concentration tested significantly affected parental survival or fertility of eggs, nor were survival and growth of progeny affected in a subsequent 28-day test. Fish exposed to 0.47 μg/liter spawned 22.6 eggs/female-day, or 69% of control production (32.8 eggs/female-day). The number of eggs spawned by fish exposed to 6.5, 3.5, 1.8, and 0.98 μg/liter Diazinon was similar (14.9–17.9 eggs/female-day), averaging 45–55% of production by control fish. Egg production by fish that had been previously exposed to 3.5 μg/liter did not change significantly following deputation for 23 to 31 days. AChE activity varied inversely with exposure concentration, fish in the highest concentration (6.5 μg/liter) averaging 71% inhibition. The concentration of Diazinon measured in adult fish exposed to 1.8, 3.5, and 6.5 μg/liter averaged 169 times the concentration measured in the water. Diazinon was not consistently detected (<0.05 mg/kg) in fish exposed to 0.98 and 0.47 μg/liter. The maximum acceptable toxicant concentration (MATC) for sheepshead minnows continuously exposed to Diazinon, based on reduced fecundity, is <0.47 μg/liter; the application factor (MATC ÷ 96-hour median lethal concentration) is <0.0003.

The sheepshead minnow (Cyprinodon variegatus) was continuously exposed for 23 wk to the organochlorine insecticide endrin, from the embryonic state through hatching until adulthood and spawing. The resultant progeny were monitored to determine the effects of the toxicant on their survival, growth, and reproduction. Average measured exposure concentrations were O (control), 0.027, 0.077, 0.12, 0.31, and 0.72 microgram/liter. Embryos exposed to 0.31 and 0.72 microgram/liter hatched early; all fry exposed to 0.72 microgram/liter died by day 9 of exposure. At 0.31 microgram/liter, fry were initially stunted and some died. Survivors seemed unaffected until maturity, when some females died during spawning; fewer eggs were fertile and survival of exposed progeny decreased. No significant effects were observed th roughout this fish's life cycle at an exposure concentration of 0.12 microgram/liter. Four-week-old juvenile fish accumulated 2,500 times the concentration of endrin in the exposure water; adults, 6,400 times; and their eggs, 5,700 times. The specific application factor (calculated by dividing the limits on the maximum acceptable toxicant concentration, greater than 0.12 and less than 0.31 microgram/liter, by the concentration lethal to 50% of the juvenile fish in 96 hr, 0.34 microgram/liter) ranged from 0.35 to 0.91. To our knowledge this is the first toxicity test carried out through the entire life cycle of an oviporous esturarine fish. Data from this experiment and from experiments with another estuarine fish and four freshwater fish all demonstrate that there is little difference between endrin concentrations that produce acute effects and concentrations that do not affect the fish in chronic exposures lasting four or more weeks.

Dynamic marine toxicity tests were performed with technical grade chlordan and eastern oysters (Crassostrea virginica), pink shrimp (Penaeus duorarum), grass shrimp (Palaemonetes pugio), sheepshead minnows (Cyprinodon variegatus), and pinfish (Lagodon rhomboides). The 96-hr LC20S (and 95% confidence limits) based on measured concentrations of chlordane (in mug/liter) are: ping shrimp 0.4 (0.3-0.6); grass shrimp, 4.8 (4.0-6.0); sheepshead minnows, 24.5 (19.9-28.6); and pinfish, 6.4 (5.0-7.3). The 96-hr EC50 for eastern oysters was 6.2 (4.8-7.9). In a flow-through test, embryos and fry of sheepshead minnows were exposed to average measured concentrations of chlordane from 1.3 to 36.0 mug/liter for 28 days. Neither fertilization success nor embryo survival was affected by the concentrations of chlordane to which these life stages were exposed. However, sheepshead minnow fry did not survive for more than 10 days in chlordane concentrations greater than 7.1 mug/liter.

An electrically operated brine shrimp feeder is described. The device may be set to cycle 1–12 times each day for tests in fish and invertebrate culture and bioassay. Major advantages of the feeder are that it is readily adapted to flow-through bioassay and culture apparatuses which require that equal quantities of food be delivered to animals in two or more test aquaria and that the number of feedings be recorded. The components, all readily available, cost approximately $190.

Transactions of the American Fisheries SocietyVolume 104, Issue 3 p. 584-588 Original Articles Effects of Aroclor(R) 1016 on Embryos, Fry, Juveniles, and Adults of Sheepshead Minnows (Cyprinodon variegatus) David J. Hansen, David J. Hansen United States Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USASearch for more papers by this authorSteven C. Schimmel, Steven C. Schimmel United States Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USASearch for more papers by this authorJerrold Forester, Jerrold Forester United States Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USASearch for more papers by this author David J. Hansen, David J. Hansen United States Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USASearch for more papers by this authorSteven C. Schimmel, Steven C. Schimmel United States Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USASearch for more papers by this authorJerrold Forester, Jerrold Forester United States Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USASearch for more papers by this author First published: July 1975 https://doi.org/10.1577/1548-8659(1975)104<584:EOAROE>2.0.CO;2Citations: 19AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Abstract We investigated the toxicity of Aroclor 1016 to, and uptake by, fry and juvenile and adult sheepshead minnows (Cyprinodon variegatus) in intermittent-flow bioassays lasting 28 days. Survival of eggs, of fry hatched from them, and of juvenile and adult fish apparently was not affected by 0.1, 0.32, 1.0, 3.2, or μg/liter of Aroclor 1016 added to aquaria, but 32 and 100 μg/liter killed newly hatched fry and juvenile and adult fish. Sheepshead minnows accumulated the chemical in proportion to its concentration in the test water. Fry contained 2,500 to 8,100 X the concentration of Aroclor 1016 added to the test water, adults 4,700 to 14,000 X, and juveniles 10,000 to 34,000 X. As much as 77 μg/g of Aroclor 1016 in eggs from exposed adults apparently did not affect survival of embryos and fry. Citing Literature Volume104, Issue3July 1975Pages 584-588 RelatedInformation

Transactions of the American Fisheries SocietyVolume 103, Issue 3 p. 582-586 Original Articles Effects of Aroclor(R) 1254 on Laboratory-Reared Embryos and Fry of Sheepshead Minnows (Cyprinodon variegatus) Steven C. Schimmel, Steven C. Schimmel U. S. Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USA Associate Laboratory of the National Environmental Research Center, Corvallis, Oregon, USASearch for more papers by this authorDavid J. Hansen, David J. Hansen U. S. Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USA Associate Laboratory of the National Environmental Research Center, Corvallis, Oregon, USASearch for more papers by this authorJerrold Forester, Jerrold Forester U. S. Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USA Associate Laboratory of the National Environmental Research Center, Corvallis, Oregon, USASearch for more papers by this author Steven C. Schimmel, Steven C. Schimmel U. S. Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USA Associate Laboratory of the National Environmental Research Center, Corvallis, Oregon, USASearch for more papers by this authorDavid J. Hansen, David J. Hansen U. S. Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USA Associate Laboratory of the National Environmental Research Center, Corvallis, Oregon, USASearch for more papers by this authorJerrold Forester, Jerrold Forester U. S. Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory, Sabine Island, Gulf Breeze, Florida, 32561 USA Associate Laboratory of the National Environmental Research Center, Corvallis, Oregon, USASearch for more papers by this author First published: July 1974 https://doi.org/10.1577/1548-8659(1974)103<582:EOAROL>2.0.CO;2Citations: 43AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Eggs of the sheepshead minnow (Cyprinodon variegatus) were artificially fertilized and maintained at temperatures from 15 to 35 C and in salinities from 0 to 35‰ to determine efficient culture conditions. Fertilization was not affected by temperature or salinity ranges chosen, but hatching success was greatest (x2; α = 0.01) at a temperature range of 24 to 35 C and a salinity range of 15 to 30‰. Artificially fertilized sheepshead minnow eggs were exposed to logarithmic concentrations of Aroclor 1254 (10.0 to 0.1 μg/liter) in seawater averaging 30 C and 24‰ in a flow-through bioassay. Fertilization was not affected but significantly fewer embryos developed in the 10.0 μg/liter concentration, and fewer fry survived in concentrations greater than 0.1 μg/liter. Fry were more susceptible to Aroclor 1254 than were embryos, juveniles, or adults. Citing Literature Volume103, Issue3July 1974Pages 582-586 RelatedInformation

Natural mortality, emigration, and yield to anglers were assessed in 1962 for three releases of cutthroat trout (Salmo clarki) in Munsel Lake, Oregon. Stocked fish were caught emigrating from March 30, the start of trapping, to July 3. Natural mortality, 16 to 75%, was the dominant factor determining the number of fish available to anglers, and this mortality was greatest when anglers could not fish immediately after stocking. Yield of trout to anglers, estimated by creel census, indicated that after release fish were removed rapidly from the lake. Catch by anglers could be increased and catch per unit effort stabilized by liberating trout just before the fishing season and once or twice in the summer. This policy could reduce losses of fish from natural mortality and emigrations.