摘要:

The effects of a thermal effluent on the distribution and condition of fishes were determined in a 330-ha reservoir in northeastern Texas. Fish were collected at five stations with 41-m experimental gill nets and a 6.1-m seine every 2 weeks between May 1971 and June 1972. Water temperatures at the mouth of the effluent canal were highest (42.2 C) in July and were typically 3-8 C higher at this location than in other areas of the reservoir. Two forage species (Mississippi silversides, Menidia audens, and pugnose minnow, Notropis emilae) were never found near the mouth of the effluent canal. White crappie (Pomoxis annularis) and river carpsucker (Cyprinus carpio) may have been attracted to the effluent area in spring and summer. Channel catfish, (Ictalurus punctatus), gizzard shad (Dorosoma cepedianum), threadfin shad (D. petenense), and bluegill (Lepomis macrochirus) were rather evenly distributed over the entire reservoir during all seasons. The size and condition of fishes collected at the mouth of the effluent canal were not significantly different from those of fish collected at other stations in the reservoir, although the condition coefficients of channel catfish, river carpsucker, gizzard shad, threadfin shad, and bluegill were lower than those reported for these species in other parts of the United States. The results suggest that in a small reservoir like North Lake the effects of a heated effluent on fish populations may be generalized over the entire body of water, particularly when a cool-water refuge area is present beneath the heated surface stratum.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<518:DACOFI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Recent habitat degradation within the desert areas of the southwestern United States and adjoining areas of Mexico has seriously depleted endemic fish populations. During the past 35 years, 4 species and 6 subspecies in 6 genera apparently have become extinct within California, Nevada, and Arizona, and at least 50 additional species and subspecies within 8 Great Basin states and northern Mexico are considered threatened. Of these, 19 are currently listed as endangered by the Secretary of the Interior. The urgency and complexity of the problem caused several governmental agencies to combine in 1970 with other concerned parties and form the Desert Fishes Council. This was done to improve communications and assist in the development of an interagency preservation program, the primary purpose of which was to reduce the rate of habitat destruction. A Pupfish Task Force established by the Department of the Interior in 1970 coordinated efforts of that agency and initiated an effective program based upon protection of native habitats. The Desert Fishes Council continues as an active participant. The methodology developed may prove useful in solving similar problems as they occur elsewhere.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<531:DFATH>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Rainbow trout fry developed whirling disease upon exposure to water contaminated with Myxosoma cerebralis. When similarly contaminated water was irradiated with 2537 Angstrom units of ultraviolet light at dosages of 35,000, 43,000, and 112,000 microwatt sec/cm2, infection of fry was prevented. The minimum effective dosage was not determined in the present experiments. High mortality and a 61% growth inhibition of survivors occurred in the infected fry.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<541:DOCWBU>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Exposure of fourth instar larvae of Chironomus tentans to 2.0-8.0 mg/liter of TFM (3-trifluormethyl-4-nitrophenol) for 6 hr at 22 ± 0.5 C in soft water resulted in a significantly increased rate of larval oxygen consumption compared to that of control larvae, as measured with the Warburg respirometer. Maximum stimulation of oxygen consumption occurred with 8.0 mg/liter of TFM, and 1.0 mg/liter of TFM had no measurable effect on basal respiration. When hardness of exposure water was progressively increased, the effect of TFM on oxygen consumption was diminished.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<551:EOTABO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Mosquitofish, Gambusia affinis, from two populations differing greatly in insecticide tolerance were tested for their ability to avoid concentrations of DDT, endrin, toxaphene and parathion in a Y-maze. Both susceptible and resistant fish avoided endrin, toxaphene, and parathion. DDT was avoided by susceptible fish but not by resistant fish. Resistant fish avoided damaging concentrations (except DDT) better than did susceptible fish.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<557:ABOISA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Two 9-month continuous-flow bioassays and several intermediate length continuous-flow tests were conducted to determine safe levels of Aroclor 1242, 1248, and 1254 for the fathead minnow (Pimephales promelas) and Aroclor 1248 for the flagfish, Jordanella floridae. Calculated 96-hr LC50 values for newly hatched fathead minnows were 7.7 μg/liter for Aroclor 1254 and 15 μg/liter for 1242. Three-month-old fatheads had a 96-hr LC50 of 300 μg/liter for 1242. Reproduction occurred at and below 1.8 μg/liter 1254 and at and below 5.4 μg/liter 1242. Newly hatched young were the most sensitive life stage. Growth of young fatheads was also affected above 2.2 μg/liter 1248, and none survived above 5.1 μg/liter after 30 days. Young flagfish did not survive at 1248 concentrations above 5.1 μg/liter and did not grow well above 2.2 μg/liter.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<562:EOPBCO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The toxicity of chlorine to juvenile chinook salmon (Oncorhynchus tshawytscha) was tested at five residual concentrations ranging from 0.05 to 1.0 mg/liter and at four temperatures (Δt 0, 2.6, 4.9, and 10 C) in a matrix design. Juvenile pink salmon (O. gorbuscha) were tested at three temperatures (Δt 0, 5.0, and 9.9 C). Each matrix was stressed at four exposure periods (7.5, 15, 30 and 60 min). An array of LC50 and LT50 values are presented for each of the conditions tested. A decrease in the tolerance of both species to residual chlorine was demonstrated with increasing temperature and exposure time. The 60-min exposure period and the 9.9 and 10 C Δt were the most acutely toxic to each species. The equilibrium loss response for chinook salmon exposed to heat and chlorine preceded the LT50 by at least 55%. The LC50 was 0.045 mg/liter for both species after exposure to fluctuating chlorine concentrations during 2-hr periods. The LT50 occurred in about 100 min at approximately 0.5 mg/liter residual chlorine.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<569:TOCAHT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Three collections of yellow perch, white bass and smallmouth bass were made in May, July and late October for analyses of DDT, PCB, mercury, copper and cadmium. Fat content varied seasonally among collections, lowest in spring and highest in fall. Total DDT residues were low for all species. Means ranged from 0.09 to 0.27 μg/g and exhibited no seasonal changes. No difference among species existed for DDT in spite of differing fat content, but concentrations within a species increased with increasing fat and subsequently age. PCB's were up to 6.5 times greater than DDT levels. PCB residues, lowest in yellow perch and highest in white bass, did not vary with season but increased with increasing fat. Dieldrin was low and no trends relating to season or fat were apparent.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<577:ORMCAC>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

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‰.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<582:EOAROL>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The herbivorous grass carp fed winter elodea exhibited a negative nitrogen balance in metabolism, suggesting that food having a higher protein content would be required for normal growth. About a third of the phosphorus contained in food was retained; hence, a combination of aquatic plants and grass carp might afford an effective biological method for removing phosphorus from water. Water quality was altered by the excretion of ammonium and orthophosphate by grass carp. Even though the grass carp might be useful in removing some phosphorus from water, its principal impact was to increase the rate of recycling of nitrogen and phosphorus.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<587:NAPBOG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor