Effects of natural exposure to copper and zinc on egg size and larval copper tolerance in white sucker (Catostomus commersoni)

Sucker eggs were collected from a metal-contaminated site where previous collections had documented a maternal yolk factor associated with an increased larval copper tolerance during yolk nutrition. In this study, white sucker eggs were divided into groups which were water hardened and/or incubated at the contaminated site or a reference (control) site. Incubation at the contaminated site was associated with a decreased egg size and an increased deformity rate, but had no effect on fertilization rate or larval size. Incubation in contaminated streams increased the larval whole-body metal content, and decreased the tolerance and resistance of larvae exposed to copper in laboratory bioassays. An increase in water temperature accelerated the developmental rate of the larvae, but had no detectable effect on copper tolerance. Although metals did enter the eggs during water hardening, there was no difference in egg metallothionein content, and the lack of obvious hepatic activity until several days after hatching may prevent the formation of protective proteins. The authors hypothesize that the transfer of metals to white sucker eggs in association with yolk precursors, and the subsequent mobilization of these metals during yolk utilization, can account for the observed differences in larval tolerance and growth.     

Effects of copper on hatching of larvae and prezoea survival of Petrolisthes galathinus (Porcellanidae): assays with ovigerous females and isolated eggs

Ovigerous females of the porcellanid crab Petrolisthes galathinus were selected for toxicological bioassays. A first assay was made on isolated eggs, exposing them to 0 (control), 0.5, or 1 mgL(-1) copper. Both copper concentrations caused significant mortality just before hatching. The few prezoeas hatched at 0.5 and 1 mgL(-1) were unable to reach the zoea stage. A second assay was conducted on the ovigerous females isolated and exposed to 0 or 0.1 mgL(-1) copper. Females were checked daily and the percentages of mortality, egg loss, and hatching larvae were recorded. No differences in either mortality of females or number of hatched larvae were noted between control and copper-exposed groups. From each of these groups, 15 recently hatched prezoeas were transferred to clean seawater, while another 15 were exposed to 0.1 mgL(-1) copper. The numbers of dead or alive prezoeas, transitional larvae, and zoeas were ascertained every 24 h. Prezoeas hatched from exposed eggs and transferred to clean seawater at hatching showed enhanced mortality and a delay in development, compared with control larvae maintained in clean water throughout. Copper at 0.1 mgL(-1) was lethal to almost all larvae exposed only after hatching, while those that had also been preexposed to copper during embryonic development showed a certain degree of tolerance to copper exposure, at least during the first 24 h after hatching.     

Toxicity of lindane to freshwater insect larvae in compartments of an experimental pond.

The acute and chronic toxicities of lindane to larvae of the freshwater insects Chironomus riparius Meigen, Chaoborus flavicans (Meigen), and Sigara striata (L.) were investigated in mesocosm compartments of an experimental pond. The following median lethal concentrations (LC50s) were determined: 240-hr LC50 of 2.0 micrograms lindane liter-1 for second instar C. riparius, 72-hr LC50 of 6.5 micrograms lindane liter-1 for fourth instar C. riparius, and 96-hr LC50s of 4.0 and 3.9 micrograms lindane liter-1 for fourth instar C. flavicans and fourth or fifth instar S. striata, respectively. Lindane significantly reduced the growth over 10 days of second instar C. riparius compared to that of the control at the treatment concentrations where larvae survived (1.0, 2.5, and 7.0 micrograms lindane liter-1). A significant increase in the median emergence time in comparison to that of the control was observed for C. riparius exposed to 0.8 and 2.0 micrograms lindane liter-1, with higher concentrations causing 100% mortality. The findings compare well with previously reported laboratory data on the toxicity of lindane to insects and support the methodology and results of a laboratory growth test for C. riparius.     

Ingestion of petroleum by breeding mallard ducks: Some effects on neonatal progeny

Breeding female mallard ducks consuming petroleum-contaminated food show significant induced increases in the naphthalene-metabolizing properties of microsomes prepared from their livers. Food contaminated with South Louisiana crude oil was more potent than food contaminated with similar concentrations of Prudhoe Bay crude oil and in each instance food contaminated with 3% (v/w) induced greater increases than food contaminated at the 1% level. These increases in hepatic naphthalene-metabolizing activity may reflect their responses to circulating petroleum contaminants derived from ingested crude oil. When incubated, fertilized eggs laid by the females consuming South Louisiana crude oil yielded ducklings that upon emergence possessed high levels of naphthalene-metabolizing activity associated with hepatic microsomes. In contrast, ducklings derived from eggs laid by females consuming food contaminated with Prudhoe Bay crude oil showed no increases in total hepatic naphthalene-metabolizing activity and only those ducklings hatched from eggs laid by females consuming food contaminated with 3% crude oil showed significantly induced levels of specific naphthalene-metabolizing activity at hatching. During the first week of postnatal life both the uncontaminated ducklings and the ducklings hatched from eggs laid by females consuming food contaminated with South Louisiana crude oil showed initial transient rises in specific and total hepatic naphthalene-metabolizing activity. In each instance, these rises were proportional to the level of contamination in the food consumed by the females. Thereafter, the specific activities of the naphthalene-metabolizing enzyme in all ducklings declined to the level found at hatching in uncontaminated ducklings. Similarly, the total hepatic naphthalene-metabolizing activities in ducklings derived from females consuming food contaminated with 3% crude oil also declined to the level at hatching in uncontaminated ducklings. In contrast, after one week, ducklings hatched from eggs laid by females consuming food contaminated with 1% crude oil showed total hepatic naphthalene-metabolizing activities that were more than twice those found at hatching.     

The Potential Association Between Menta Deformities and Trace Elements in Chironomidae (Diptera) Taken from a Heavy Metal Contaminated River

Elevated morphological deformity rates in Chironomidae larvae have been attributed to such pollutants as oil tars, pesticides, organochlorines, and heavy metals. The potential of chironomids as biological indicators of heavy metal contamination and bioavailability in a contaminated ecosystem was assessed. Chironomid larvae and river sediment were collected from the Coeur d' Alene River system, Idaho, USA, contaminated with heavy metals from mining activities. Chironomid larvae collected at contaminated sites exhibited mouthpart deformity proportions between 3.8 and 10.3% compared to the control site of 0.9%. As, Cd, Cu, Ni, Pb, and Zn were determined in both larvae and sediment samples. Significant correlation between metal concentrations and deformity rates were observed for all metals except Ni. The data also suggests that feeding habits may influence differences in pollution tolerance among genera. Received: 18 June 2001/Accepted: 25 October 2001     

Influence of larval period on responses of overwintering green frog (Rana clamitans) larvae exposed to contaminated sediments

Pond-breeding amphibians exhibit large intra- and interspecific differences in the duration of the aquatic larval phase. In contaminated aquatic environments, a prolonged larval phase means prolonged exposure to pollutants and, potentially, more severe toxic effects. In the laboratory, we tested this hypothesis by exposing green frog larvae (Rana clamitans) to commercial clean sand (control), sediment from an abandoned surface mine (mine), or sediment contaminated with coal combustion waste (CCW). By collecting eggs late in the breeding season, we obligated larvae to overwinter and spend a protracted amount of time exposed to contaminated sediments. The experiment was continued until all larvae either successfully completed metamorphosis or died (301 d). Larvae exposed to mine sediments accumulated significant levels of Pb and Zn, whereas larvae exposed to CCW-contaminated sediment accumulated significant levels of As, Se, Sr, and V. Larvae exposed to mine sediments suffered sublethal effects in the form of reduced growth and size at metamorphosis, but the proportion of larvae successfully completing metamorphosis (93%) was the same for both control and mine treatments. In contrast, larvae exposed to CCW-contaminated sediment suffered greatly reduced survival (13%) compared to both control and mine treatments. Moreover, among larvae in the CCW treatment, the majority of mortality occurred during the latter part the overwintering period (after day 205), corresponding to the onset of metamorphosis in the controls. Our results suggest that the length of the larval period may be one of many life-history or ecological characteristics that influence the sensitivity of aquatic breeding amphibians to environmental pollutants.     

Copper tolerance in fathead minnows: I. The role of genetic and nongenetic factors

Swim performances of male and female fathead minnows (Pimephales promelas) from three different suppliers were determined before and after an 8- to 9-d exposure to 175 microg/L copper (Cu). The reduction in swim performance (delta) due to the Cu exposure varied widely among individual fish, but was surprisingly consistent from one supplier to the next and between males and females. Genetic analysis of the individuals revealed significant correlations between delta and genotypic variation at the glucosephosphate isomerase-1, phosphoglucomutase-1, and lactate dehydrogenase-2 enzyme loci. Based upon delta, the most Cu-resistant fathead minnows were bred together, as were the most Cu-susceptible individuals and two groups of unselected minnows. Larvae produced by each group of adults were subjected to a survival test. The median lethal concentration (LC50) for larvae produced by Cu-resistant adults was significantly greater than the LC50s for the control groups. Surprisingly, the LC50 for the larvae produced by Cu-susceptible adults was also significantly greater than the LC50s for the control groups, but not significantly different from the larvae produced by Cu-resistant parents. While Cu tolerance has a genetic component in fathead minnows, the Cu tolerance of larval fish appears to be influenced by nongenetic as well as genetic factors.     

Chronic toxicity of copper to a partial life cycle of the midge,Chironomus decorus

The development and hatchability ofChironomus decorus eggs were not affected by 0.1 to 5 mg/L of copper in water. The embryos developed normally and hatched at about the same time (after 55 hr of incubation). All larvae survived the duration of the test (72 hr) except those subjected to 5 mg/L of copper in water, which died after only partial emergence from the egg shell. Apparently, eggs were protected by their shell from copper. Growth ofC. decorus larvae was reduced significantly when they were reared in copper-spiked food-substrate (bound copper) from the age 1 to 15 days old (900–4,500 mg/kg of copper). The substrate copper concentration at which larval growth was reduced to 50% (EC50) was 1,602 mg/kg. Substrate copper caused deformities in the epipharyngeal plate of larval mouthparts and copper concentration higher than 1,800 mg/kg delayed adult emergence. The copper concentration in pupal exuviae and adults were positively correlated to copper concentration in the substrate in which they had been reared as larvae. Larval stage appeared to be the most sensitive to copper toxicity, while eggs were the least sensitive. Larval growth was the best indicator in detecting copper pollution, since it could detect copper at relatively low concentrations. The time to adult emergence was not considered a very good indicator, while larval deformities offered a quick tool to evaluate copper pollution.     

Selenium in eggs and milt of razorback sucker (Xyrauchen texanus) in the middle Green River,Utah

Eggs from three female and milt from five male endangered razorback suckers (Xyrauchen texanus) were collected from the Razorback Bar (about 20 km upstream of Ashley Creek) in the Green River of northeastern Utah. Eggs, but not milt, had concentrations of selenium that were above the range of selenium concentrations in control fish from laboratory studies or reference fish from field studies. The concentrations, however, were below those reported in selenium-exposed fish that had reproductive problems in laboratory studies or field investigations. Tests with three streamside spawned pairs of razorback suckers, which were sampled for eggs and milt in this study, resulted in no hatching of fertilized eggs. Concentrations of selenium in eggs and milt were significantly correlated with selenium concentrations in muscle plugs taken from the same fish, but egg and milt concentrations were not significantly different from muscle plugs. Selenium concentrations in eggs of razorback suckers in the Green River may be sufficiently elevated to cause reproductive problems that are contributing to the decline of this species in the upper Colorado River basin.     

Whole-body arsenic concentrations in rainbow trout during acute exposure to arsenate.

This research explored the influence of temperature and waterborne arsenate exposure level on the whole-body arsenic (As) concentration in rainbow trout (Oncorhynchus mykiss) at loss of equilibrium (LOE), an acute toxicity endpoint. The mean median times (ET50s) to LOE for fish exposed to 120 mg arsenate liter-1 at 5 degrees C, as well as 60 and 120 mg liter-1 at 15 degrees C were 56.8, 210, and 34.8 hr, respectively. Despite the differences in ET50, the fish showed respective mean (SE) whole-body As concentrations of 8.6 (0.3), 8.1 (0.6), and 8.6 (0.4) micrograms As g-1, values which were not significantly different. Fish exposed to 240 mg arsenate liter-1 at 5 degrees C, which had a LOE ET50 of 32.2 hr, were observed to have a mean (SE) whole-body arsenic concentration of 13.5 micrograms g-1, significantly higher than the levels in fish from all other treatments. A 3-hr delay between LOE and sampling did not significantly alter whole-body As concentration. The results are discussed in terms of the utility of using whole-body As concentrations to interpret the impacts of arsenate on fish populations in the field.     

Hazard assessment of selenium and other trace elements in wild larval razorback sucker from the Green River, Utah

Contaminant investigations of the Green River in northeastern Utah have documented selenium contamination at sites receiving irrigation drainage. The Green River provides critical habitat for four endangered fishes including the largest extant riverine population of endangered razorback sucker. Although 2175 larval razorback suckers were collected from the river between 1992 and 1996, very few juveniles have been captured within recent decades. Selenium concentrations were measured in larval razorback suckers collected from five sites in the Green River (Cliff Creek, Stewart Lake Drain, Sportsman's Drain, Greasewood Corral, and Old Charlie Wash) to assess the potential for adverse effects on recruitment of larvae to the juvenile stage and the adult population. Larvae from all sites contained mean selenium concentrations ranging from 4.3 to 5.8 microg/g. These values were at or above the proposed toxic threshold of 4 microg/g for adverse biological effects in fish, which was derived from several laboratory and field studies with a wide range of fish species. At two sites, Cliff Creek and Stewart Lake Drain, selenium concentrations in larvae increased over time as fish grew, whereas selenium concentrations decreased as fish grew at Sportsman's Drain. Evaluation of a 279-larvae composite analyzed for 61 elements demonstrated that selenium and, to a lesser extent, vanadium were elevated to concentrations reported to be toxic to a wide range of fish species. Elevated selenium concentrations in larval razorback suckers from the five sites suggest that selenium contamination may be widespread in the Green River, and that survival and recruitment of larvae to the juvenile stage may be limited due to adverse biological effects. Selenium contamination may be adversely affecting the reproductive success and recruitment of endangered razorback sucker.     

Effect of fenitrothion on reproduction of the freshwater prawn Macrobrachium lamerrii

Acute and toxic effects of fenitrothion on eggs and larvae of Macrobrachium lamerrii have been studied. The hatching success of the eggs is not affected when berried females are exposed to fenitrothion. No drastic changes in egg production are seen at sublethal levels, while at higher concentrations females abort their eggs. The first-stage larvae hatching in subacute chronic exposure are not morphologically abnormal. The rate of heart pulsation in embryos and larvae increased under pollutant stress. Larvae are highly susceptible and death rate of larvae does not increase during molt period. On chronic exposure there are drastic changes in the gonads of M. lamerrii.     

Laboratory breeding of the European rabbit flea, Spilopsyllus cuniculi (Dale).

A method is described for the laboratory breeding of the rabbit flea in which the immature stages are reared at constant temperature and humidity. Eggs are obtained by confining fleas taken from a rabbit and her nest shortly after parturition with two of her nestlings in an incubator for 24 h. The eggs are transferred to an artificial diet medium on which the immature stages are reared. On average a female flea produces 50 eggs during the first six days post-partum. At 25 degrees C, 95% of eggs hatched at 79% RH and 98% at 84% RH. Most eggs hatched on the third day after laying and hatching was completed by the fourth day. Significantly more fleas of both sexes were obtained when larvae were reared at 25 degrees C on a medium containing powdered 41B rodent diet than on one containing terrier meal. Both diets also contained yeast and dried rabbit blood. There was no significant difference between the numbers of fleas obtained at 79% RH and 84% RH. Significantly more fleas were also obtained when larvae were reared at 27 degrees C, 84% RH, than at 25 degrees C. Female fleas emerged sooner than males at both 27 degrees C and 25 degrees C. Fleas from the laboratory culture were heavier than those from wild nests. Female fleas were heavier than male fleas in both cases.     

The effects of salinity and temperature on the toxicity of copper to 1-day and 7-day-old larvae of Hediste (Nereis) diversicolor (O. F. Muller)

The effects of salinity and temperature on the toxicity of copper to 1-day and 7-day-old larvae of Hediste diversicolor were tested using factorial analysis. Mortality of larvae was influenced by salinity, temperature, and copper, but 1-day-old larvae were more susceptible than the 7-day-old larvae. Resistance to copper increased with age. Low concentrations of 5 and 20 micrograms/liter copper were more inhibitory to 1-day and 7-day old larvae, respectively, than were higher copper levels. The responses of 1-day-old larvae to copper levels from 0 to 20 micrograms/liter and 7-day-old to copper levels from 0 to 100 micrograms/liter copper were complex. Increasing salinity 7.6 to 30.5% reduced both copper toxicity and protozoa/bacteria attacks.     

The Effect of Bioaccumulated Selenium on Mortalities and Deformities in the Eggs, Larvae, and Fry of a Wild Population of Cutthroat Trout (Oncorhynchus clarki lewisi)

To determine if elevated concentrations of waterborne selenium (Se), caused by coal mining, in the Elk River in southeastern British Columbia, may be causing reproductive or teratogenic effects in wild cutthroat trout (Oncorhynchus clarki lewisi), fertilized eggs from exposed and reference fish were raised in the laboratory. Eggs from each female were reared separately and the percent mortalities and deformities were related to the selenium content of the eggs. Selenium concentrations in females from the exposed site were highest in the liver (36.6 ± 22.5 μg/g dry weight, range: 18.3 to 114), followed by the eggs (21.0 ± 18.3 μg/g, range: 8.7 to 81.3) and the muscle (12.5 ± 7.7 μg/g, range: 6.7 to 41). Despite these elevated egg Se concentrations, there was no significant effect on fertilization; time to hatch; percent hatch; or egg, larvae, and fry deformities or mortalities. Reproductive failure and embryonic terata have been reported at much lower egg Se concentrations in other fish species. The lack of any toxic response in this study may be due to an evolved tolerance to higher tissue Se concentrations in a population of fish living in a seleniferous river system. Received: 16 August 1999/Accepted: 28 December 1999     

Hepatic steatosis in zebra fish (Brachydanio rerio) induced by long-term exposure to gamma-hexachlorocyclohexane.

In a full life cycle test, newly hatched eggs of zebra fish, Brachydanio rerio, were reared to sexual maturity under continuous exposure to 40, 80, 110, 130, and 150 micrograms/liter lindane, gamma-hexachlorocyclohexane. The effects of lindane were investigated by recording behavior and survival of the F0- and F1-generation as well as morphological alterations in liver ultrastructure of F0. Changes in peroxisomes were visualized by cytochemical staining for catalase activity with diaminobenzidine. Whereas behavioral changes can already be observed at 40 micrograms/liter, survival and number of eggs in F0 as well as survival and growth of F1 are unaffected by up to 80 micrograms/liter lindane. At concentrations greater than or equal to 110 micrograms/liter, survival of larvae is reduced already after 35 days, and mortality is 100% after 3 months. From 40 micrograms/liter, liver ultrastructure displays a microvesicular fatty vacuolation (steatosis) characterized by lipid deposition within the cisternae of the RER. At 40 micrograms/liter, this highly specific pathological change is accompanied by accumulation of hepatic macrovesicular triglyceride droplets, glycogen depletion, and the occurrence of club-shaped mitochondria. Additional alterations at 80 micrograms/liter comprise proliferation of SER in males and progressive fractionation of RER in females, stacking of club-shaped mitochondria, a conspicuous decrease in peroxisomal catalase activity, infiltration of macrophages into the liver parenchyma, and a significant stimulation of hepatocytic mitosis. Among several substances tested so far in zebra fish (4-nitrophenol, 4-chloroaniline 3,4-dichloroaniline, atrazine, lindane), lindane is the only compound inducing behavioral changes and hepatic steatosis in conjunction with a reduction in fertility. With regard to the relative sensitivity of the methods applied, behavioral and cytological studies appear more responsive to lindane exposure than survival studies.     

Copper tolerance in fathead minnows: II. Maternal transfer

Female fathead minnows (Pimephales promelas) exposed to copper (Cu) maternally transfer Cu tolerance to their larval offspring. Larvae produced after female parents received a sublethal 5-d, 100 microg/L Cu exposure had significantly greater survivorship in potentially lethal Cu solutions than larvae produced before those females were exposed to Cu.     

Laboratory colonization and life cycle of Coquillettidia crassipes in Malaysia

Methods are described for the laboratory colonization of Coquillettidia crassipes. The highest rate of insemination occurred in 60 x 60 x 120 cm cages and better insemination in laboratory adapted F15 generation. Embryonation and hatchability of eggs ranged from 69.6 to 97.9% and 63.3 to 94.3% respectively. Gravid females laid egg rafts on water in 500 ml breakers with small leaves of Salvinia for resting. Newly hatched larvae were set up in a basal medium of guinea pig dung and water or liver powder, yeast powder and water. Larvae attached to aquatic plants or 'Keaykolour' ruffia snow white paper. The cultures with paper gave better yields. At present 21 generations of Cq. crassipes have been reared in the laboratory.     

Pikes (Esox lucius L.) shown to be affected by low pH values during first weeks after hatching.

Newly hatched pike (Esox lucius L.) sac fry from artificially fertilized eggs were reared for eight days in water solutions with different pH values. At pH 6.8 the mortality was 17%, 26% at pH 5.0, and 97% at pH 4.2.     

Insecticide susceptibility of Aedes aegypti from Santo Domingo, Dominican Republic.

The insecticide susceptibility of Aedes aegypti adults and larvae from Santo Domingo, Dominican Republic, was investigated using World Health Organization standard procedures. A field strain was more resistant to insecticides than a colony strain that originated from the same place. Larvae produced from ovitrap-collected eggs were resistant to temephos (78.2% mortality on exposure to 0.025 mg/liter). Mortality rates after exposure of adults to discriminating concentrations showed that wild populations were resistant to DDT, malathion, propoxur, permethrin and deltamethrin. The problem of resistance was considered serious enough to warrant consideration of control measures other than the use of chemicals.