Differences in the effects of mercury on Telson regeneration in two populations of the grass shrimpPalaemonetes pugio

AdultPalaemonetes pugio were collected from two tidal creek systems, Piles Creek (PC), a mercury polluted estuary, and Big Sheeps head Creek (BSC), a relatively non-polluted creek in New Jersey. Telsons were ablated from shrimp in each population. Twenty ablated individuals from each population were placed in each of the following concentrations: 20 g/L artificial sea water (ASW), 20 g/L ASW with 0.01 mg/L mercuric chloride (HgCl₂), or 20 g/L ASW with 0.01 mg/L methyl-mercuric chloride (meHg). In addition, 20 BSC shrimp were pre-treated with each of the following prior to ablatement: 0.01 mg/L HgCl₂ or 0.01 mg/L meHg. No significant difference between the control group and treated animals was noted in the PC population with respect to all parameters examined. Significant differences (P < 0.05) existed between BSC controls and BSC shrimp treated with HgCl₂, which had not been pre-treated, with respect to survival at molt, in that controls had a greater survival rate. No such difference was noted between BSC control animals, and animals pretreated with HgCl₂. In addition, BSC shrimp treated with meHg had a significantly (P < 0.05) shorter intermolt period when compared to BSC control shrimp, and BSC meHg pre-treated shrimp had a significantly shorter intermolt period than did meHg-treated shrimp which had not been pretreated.     

Effects of methylmercury on sperm and egg viability of two populations of killifish (fundulus heteroclitus)

Exposure of sperm of killifish (Fundulus heteroclitus) from a relatively clean area in Long Island (LI) to 0.01 mg/L methylmercury (meHg) in 15%o sea water caused significant reduction of fertilization success. However, exposure of killifish sperm from polluted Piles Creek (PC) to either 0.01 or 0.05 mg/L meHg in 15%o sea water prior to insemination had no effect on fertilization success. Exposure of LI killifish sperm to 0.05 mg/L meHg caused significant reduction in motility. However, PC killifish sperm showed no significant difference in motility between 0 and 0.05 mg/L meHg exposure. Exposure for 5 min to 0.05 mg/L meHg caused significant reduction in motility. These data indicate that meHg is less toxic to PC killifish sperm than LI killifish sperm. Exposure of PC and LI killifish sperm to 0.05 mg/L meHg for 15 min had no effect on sperm morphology. PC killifish sperm also showed higher (20 min) motility in 15%o sea water than LI killifish sperm (10 min). Exposure of PC and LI killifish eggs up to 25 min to 0.05 mg/L meHg prior to fertilization had no effect on fertilization success.     

Toxicity of methylmercury,mercuric chloride,and lead in killifish (Fundulus heteroclitus) from Southampton,New York

We have previously found great differences in susceptibility to teratogenic effects of methylmercury (meHg) among batches of eggs produced by different females of Fundulus heteroclitus. In the present study we investigated the relationships of resistance to meHg by a batch of eggs with other parameters of resistance. There was a positive correlation between embryonic meHg resistance and HgCl₂ resistance, although HgCl₂ generally caused less severe defects at a given dose level. The batches that were more susceptible to meHg had a greater uptake of mercury than the more resistant batches. There was a negative correlation of meHg resistance and Pb resistance (as measured by a skeletal index hatching), however. There was a positive correlation of meHg resistance of embryos and the subsequent meHg resistance of larvae after hatching.     

Effect of methylmercury on egg and juvenile viability in two populations of killifish Fundulus heteroclitus

Killifish (Fundulus heteroclitus) eggs from a polluted creek (Piles Creek (PC)) and a relatively pristine estuary in Long Island (LI) were exposed for 20 min to various concentrations of methylmercuric chloride (MeHg) prior to combination with untreated sperm. PC killifish eggs showed a higher LC50 value (1.7 mg/liter) than LI eggs (0.7 mg/liter). PC eggs that were fertilized by nontreated sperm after exposure to 1.0 or 2.5 mg/liter meHg and then placed in clean sea water (15 parts per thousand) for 1 week showed a 5 and 7% malformations of the embryos, respectively. However, exposure of LI eggs to 1.0 mg/liter prior to fertilization caused 32% malformations of the embryos, and at 2.5 mg/liter almost all the embryos died. The data indicate that LI killifish eggs are less tolerant to meHg than PC eggs. This is in keeping with previous data on embryonic tolerance to meHg in these two populations. However, 96-hr LC50 values of juvenile fish (25-45 mm standard length) did not differ between these two populations.     

Effects of Methylmercury on Ontogeny of Prey Capture Ability and Growth in Three Populations of Larval Fundulus heteroclitus

We used three populations of mummichogs (Fundulus heteroclitus), one from a polluted site (Piles Creek [PC], New Jersey) and two from cleaner sites (Tuckerton [TK], New Jersey, and East Hampton [EH], New York), to study (1) whether embryonic, embryonic plus larval, or larval exposure to methylmercury (MeHg) altered larval prey capture ability and growth; and (2) whether there were differences in tolerance to MeHg-induced behavioral changes among the three populations. Eggs and sperm were obtained from mummichogs captured in the field, and their embryos and larvae were kept in clean sea water or MeHg solution (5, 10 μg/L). Larvae were then tested regularly for prey capture rates and prey capture efficiencies, and their lengths were measured. Embryonic exposure to MeHg induced transitory and recoverable impairments in larval prey capture ability, whereas larval exposure alone was relatively ineffective. When both embryos and larvae were treated, larval prey capture ability was affected at a lower concentration and a wider range of larval ages. In terms of growth and prey capture ability, response of larvae to embryonic or larval or exposure to both stages to MeHg varied with populations. TK fish were the most tolerant with respect to behavioral changes but were the most sensitive to MeHg in reduction of growth. EH fish were the most sensitive whenever embryos were treated, and PC fish were the most vulnerable after larval exposure. The population differences in response to MeHg intoxication may be due to pollution related factors or differences in behavioral-related genetic factors. Received: 23 February 2000/Accepted: 21 January 2001     

Selenium impacts on razorback sucker, Colorado: Colorado River III. Larvae

Razorback sucker (Xyrauchen texanus) larvae from adults exposed to selenium at three sites near Grand Junction, Colorado, for 9 months were used in a 30-day waterborne and dietary selenium study. Selenium concentrations in water averaged <1.6 microg/L from 24-Road, 0.9 microg/L from Horsethief, 5.5 microg/L from Adobe Creek, and 10.7 microg/L from the North Pond. Selenium in dietary items averaged 2.7 microg/g in brine shrimp, 5.6 microg/g in zooplankton from Horsethief east wetland, 20 microg/g in zooplankton from Adobe Creek, and 39 microg/g in zooplankton from North Pond. The lowest survival occurred in larvae fed zooplankton rather than brine shrimp. Survival of larvae at Adobe Creek and North Pond was lower in site water than in reference water. Survival of brood stock larvae was higher than Horsethief larvae even though they received the same water and dietary treatments. Arsenic concentrations in brine shrimp may have resulted in an antagonistic interaction with selenium and reduced adverse effects in larvae. Deformities in larvae from North Pond were similar to those reported for selenium-induced teratogenic deformities in other fish species. Selenium concentrations of 4.6 microg/g in food resulted in rapid mortality of larvae from Horsethief, Adobe Creek, and North Pond, and suggested that selenium toxicity in the Colorado River could limit recovery of this endangered fish.     

Methylmercury effects on regeneration and ecdysis in fiddler crabs (Uca pugilator,U. pugnax) after short-term and chronic pre-exposure

Methylmercury (meHg) inhibits limb regeneration and molting in fiddler crabs. The present study shows that, inUca pugilator from a clean site, the inhibitory effects of 0.5 Μg/ml meHg were unaffected by short term pre-exposure to low levels (0.06 or 0.1 Μg/ml) of meHg under laboratory conditions. Chronic exposure tests onUca pugnax showed that the inhibitory effects of meHg varied with the sex of the crabs and the level of contamination at the site of collection. These effects were less pronounced in crabs from an area subjected to heavy metal pollution (Piles Creek, Linden, NJ) than in crabs from a relatively cleaner area (Big Sheeps-head Creek, Tuckerton, NJ). The order of susceptibility to meHg according to its interaction with sex and site from least susceptible to most was: Piles Creek females, Piles Creek males, Tuckerton males, Tuckerton females. Residue analysis showed that all groups absorbed equivalent amounts of mercury, but only the females from Piles Creek were able to depurate to near control levels after two weeks in clean water.     

Acute Toxicity of Sodium Metabisulphite in Larvae and Post-Larvae of the Land Crab, <Emphasis Type="Italic">Cardisoma guanhumi</Emphasis>

Sodium metabisulphite (SMB) is used in marine shrimp aquaculture to prevent the occurrence of black spot. The release SMB into the estuarine environment from shrimp farm pond effluents has been reported. This study evaluated the susceptibility of larvae and post-larvae of land crab, Cardisoma guanhumi to this salt. A decrease in dissolved oxygen and pH occurred with increasing concentration of SMB and exposure time. LC₅₀ values after 48 h of exposure were 34 ± 1.1 mg/L, 31.1 ± 1.9 mg/L, and 30.6 ± 0.5 mg/L for I zoea larvae, megalopa larvae and stage I juveniles, respectively.     

Accumulation and Depuration of Cd and its Effect on the Expressions of Metallothionein and Apoptotic Genes in Litopenaeus vannamei

We investigated cadmium (Cd) accumulation in muscles, gills and hepatopancreas of Litopenaeus vannamei following 48 h exposure to 5.25 mg/L, and depuration of Cd in these tissues on 1, 5 and 15 d post exposure. We also detected the expressions of metallothionein (MT), caspase-3 and p53 in hepatopancreas of shrimp exposed to 0, 5.25 and 10.5 mg/L Cd (the 24 h median lethal concentration, 24 h LC₅₀) at 0, 3, 12, 24 and 48 h. Cd accumulated with high concentration in hepatopancreas, and low concentration in muscles. Cd depurated fast in hepatopancreas and gills. MT expression increased in a time-dependent manner after Cd exposure. The p53 and caspase-3 increased at 12 and 24 h in 10.5 mg/L group. In conclusion, the accumulation and depuration of Cd in three tissues were tissues-specific. The changes of the expressions of MT, p53 and caspase-3, were stress response of L. vannamei under Cd exposure.

     

Response of a freshwater bacterial community to mercury contamination (HgCl2 and CH3HgCl) in a controlled system

An experimental study was made on the effects of inorganic mercury (HgCl₂) and methylmercury (CH₃HgCl) on freshwater aerobic heterotrophic bacterial population. The experimental system was based on two-compartment biotopes: natural sediment, from the Garonne River, and dechlorinated tap water. The response of bacterial communities to mercury additions (to the water column) was monitored by determining total Hg in water and enumerating the total number of bacteria and the evolution of the mercury resistant community. Isolation was carried out by plate count method. Enumeration of mercury resistant strains was made with a general medium (Iron-Tryp-tone agar) amended with 10 g Hg/ml of HgCl₂. The response to 2 g Hg/L (HgCl₂) was fast approximately 50% of the maximum percentage of mercury resistant bacteria being reached after one hour (21.7% after 17 h exposure). Spikes of CH₃HgCl (2 g Hg/L) in the water column caused an initial inhibition of growth of Hg-resistant and sensitive bacteria followed by a complete recovery of the background microbial population after 84 h. Seven mercury resistant bacterial strains were isolated from the experimental systems and each of them was checked for HgCl₂ and CH₃HgCl transformation. All were able to volatilize HgCl₂ by producing elemental mercury, but none was able to degrade methylmercury. Additions of different concentrations of HgCl₂ (0.02 g Hg/L to 2 g Hg/L) to the water column caused a proportional increase in the percentage of mercury-resistant bacteria. Low concentrations (<0.6 g Hg/L) of CH₃HgCl also induced the Hg-resistant community, whereas 2 g Hg/L of CH₃HgCl inhibited the growth of both Hg-sensitive and Hg-resistant heterotrophic bacteria.     

An insect model for assessing mercury toxicity: Effect of mercury on antioxidant enzyme activities of the housefly (Musca domestica) and the cabbage looper moth (Trichoplusia ni)

The effect of mercury as Hg₂Cl₂ and HgCl₂ on the antioxidant enzyme levels and its toxicity was investigated in an insect model comprised of adult females of the common housefly, Musca domestica, and fourth-instar larvae of the cabbage looper moth, Trichoplusia ni. HgCl₂ was found to be more toxic than Hg₂Cl₂ to both M. domestica and T. ni. The LC₅₀s for M. domestica were 1.17% and 0.38% w/v concentration for Hg₂Cl₂ and HgCl₂, respectively. For the more tolerant T. ni, the LC₅₀s were 5.15% for Hg₂Cl₂ and 0.96% w/w concentration for HgCl₂. The minimally acute LC₅ dose of both oxidation states of Hg was approximately 0.005% for both insects (w/v for M. domestica and w/w for T. ni). At the LC₅, both forms of Hg significantly induced the activity of superoxide dismutase in both insect species. Catalase was induced by both Hg₂Cl₂ and HgCl₂ in M. domestica but was only induced by HgCl₂ in T. ni. Glutathione-S-transferase, its peroxidase activity, and glutathione reductase activites were also significantly altered in most cases by Hg in both insects although the pattern of alteration was different between the two insects. It is evident that mercury induces oxidative stress in insects as it does in vertebrates. Our findings suggest that insects may serve as a valuable, non-mammalian model species to assess Hg-induced oxidative stress as a component of environmental toxicity.     

Chronic effects of inorganic and organic mercury onDaphnia magna: Toxicity,accumulation, and loss

The chronic toxicity of mercury (Hg) toDaphnia magna was studied under flow-through and renewed static conditions. Concentrations of mercuric chloride (HgCl₂), methyl mercuric chloride (MMC) and phenyl mercuric acetate (PMA) in flow-through tests significantly affecting survival were 1.92, between 0.26 and 0.98, and 2.25g Hg/L, respectively. Concentrations of HgCl₂, MMC, and PMA significantly impairing young production (P0.05) were 0.72, 0.04, and 1.90g Hg/L, respectively. Body accumulation of mercury was greatly influenced by the chemical form of mercury in the water. About nine times more mercury, added as MMC, was tolerated in daphnids at water concentrations permitting survival than was tolerated when added as HgCl₂. At about the same mercury concentration in water (0.26g Hg/L) daphnids accumulated 20 times more mercury when it was added as MMC than when it was added as HgCl₂. Mercury was rapidly accumulated in daphnids; however, 35 and 57% of the mercury added as MMC and HgCl₂, respectively, was lost when animals were placed in control water for four days following exposure. Different forms of mercury behaved quite differently in renewed-static and flow-through systems. The results also indicate the shortcomings of renewed-static tests with volatile and readily degradable compounds.     

Effects of carvacrol and thymol on the antioxidant and detoxifying enzymes of Rhipicephalus microplus (Acari: Ixodidae)

The present study was conducted to evaluate the effects of carvacrol and thymol on the antioxidant and detoxifying enzymes of larvae from two populations of R. microplus: Jaguar (tick population resistant to six classes of acaricides) and Porto Alegre (susceptible tick population). Carvacrol and thymol were tested at concentrations ranging from 0.14 to 5.0 mg mL^?1 in both populations to determine the LC₅₀. In addition, the LC₁, LC₂₅, and LC₇₅ were estimated using the LC₅₀ and HillSlope of each compound. Larvae of both populations of R. microplus were then treated with the LC₁, LC₂₅, LC₅₀, and LC₇₅ of each monoterpene, and those that survived were processed to evaluate the effects of the compounds on the antioxidant and detoxifying systems of larvae; these effects were assessed by determining the activity of the enzymes, glutathione-S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX). Larvae from the Jaguar population treated with different lethal concentrations of carvacrol and thymol displayed a dose-dependent increase in CAT, GPX, SOD, and GST after treatment with LC₂₅. Further, larvae treated with the LC₇₅ had the highest levels of enzyme activity for carvacrol (1.76 mg mL^?1) and thymol (1.32 mg mL^?1). CAT, GPX, SOD, and GST activity in Porto Alegre population larvae treated with carvacrol and thymol also increased significantly up to the LC₅₀ of each monoterpene. However, at the LC₇₅ of carvacrol and thymol, a decrease in the activity of all enzymes was observed for this tick population. These findings indicate that carvacrol and thymol induced increased activity of all evaluated enzymes at different lethal concentrations in R. microplus larvae from two populations. Such findings unveil the possible mechanisms of action of these natural acaricides.     

Tissue-specific cadmium accumulation, metallothionein induction, and tissue zinc and copper levels during chronic sublethal cadmium exposure in juvenile rainbow trout

Juvenile rainbow trout, on 3% of body weight daily ration, were exposed to 0 (control) or 3 μg/L Cd (as Cd(NO₃)₂· 4H₂O) in moderately hard (140 mg/L as CaCO₃), alkaline (95 mg/L as CaCO₃, pH 8.0) water for 30 days. Particular attention focused on Cd burden in tissues (gills, liver, kidney, and whole body) and induction of metallothionein (MT) in gills, liver, and kidney during chronic Cd exposure. Mortality in Cd-exposed fish was minimal (∼10%), and no growth effects occurred over the 30-day exposure. Cd accumulated in a time-dependent fashion to 9 times (gills), 3 times (liver), 20 times (kidney), 2 times (carcass), and 2 times (whole body) control levels by 30 days; absolute concentrations were in the order kidney > gill > liver > whole body > carcass. Tissue (gills, liver, and kidney) Zn and Cu burdens were not altered by chronic exposure to 3 μg/L Cd. MT concentrations in all tissues increased over the 30 days of Cd exposure, but the increases were much less than those of Cd on a molar binding site basis. Absolute MT concentrations were in the order liver > kidney > gill, but relative increases were greatest in kidney (fourfold), followed by gills (twofold) and liver (1.3-fold). MT levels were sufficient to bind all Cd in gill, liver, and kidney under control conditions, and after chronic Cd exposure remained sufficient in liver and kidney, but not in gills. Total metal levels (Cd + Zn + Cu) greatly exceeded MT binding capacity in all tissues under all conditions. Received: 20 February 2001/Accepted: 20 May 2001     

Ultrastructural changes in renal proximal tubules after chronic organic and inorganic mercury intoxication.

Adult male rats were intoxicated daily with CH₃HgCl and HgCl₂ (1.0 mg/kg BW). Kidneys were sampled for electron microscopic and histochemical evaluation as well as neutron activation analysis between 1 day and 6 weeks of the experimental period. Ultrastructural changes were confined primarily to the pars recta segment of proximal tubules. HgCl₂ induced epithelial changes, observed at 5 days, consisted of apical vacuolation, mitochondrial swelling with dilation of cristae and calcinosis. Marked increase in lysosomal profiles, formation of membranous cytosomes and isolated cellular necrosis were observed after 14–21 days of CH₃HgCl intoxication. Electron microscopic histochemical studies demonstrated mercury within mitochondria, lysosomes, microbodies, cytomembranous profiles and on cellular membrane structures. Neutron activation analysis demonstrated highest kidney total mercury levels after 5 days (HgCl₂) and 6 weeks (CH₃HgCl) intoxication.     

Effects of Mercury on the Isolated Perfused Rat Tail Vascular Bed Are Endothelium-Dependent

The effects of mercury on vascular smooth muscle results in vasoconstriction, but the mechanism of this action is not elucidated yet. To investigate this issue we examined the effects of HgCl₂ in the isolated rat tail vascular bed. The tail artery was dissected, cannulated, and perfused at a constant flow (2.5 ml/min) with Krebs solution plus EDTA 0.03 mM at 36°C. After equilibration for 30 min the effects of increasing concentrations of HgCl₂ (0.5, 1, 2, 5, and 10 μM) on the perfusion pressure were investigated. Concentrations of HgCl₂, 2 μM and above, significantly increased perfusion pressure. Blockade of α receptors (prazosin 84 ng/ml) did not alter the responses to HgCl₂, suggesting that the metal does not induce the release of neurotransmitters from sympathetic nerve terminals. To investigate the possible role of endothelium on the vasoconstriction produced by HgCl₂, preparations were precontracted with 10⁻⁷ M phenylepherine or perfused with 5 μM HgCl₂ for 20 min. Acetylcholine-vasodilated preparations precontracted with phenylepherine demonstrating the integrity of the endothelial nitric oxide–releasing mechanism. In contrast, after perfusion with 5 μM HgCl₂, the vasodilation produced by acetylcholine was abolished. In the presence of either phenylephrine or HgCl₂ the effects of sodium nitroprusside remained unchanged. Pretreatment with 30 μM indomethacin fully prevented the HgCl₂-induced vasoconstriction. However, the endothelium-dependent vasodilation in response to acetylcholine was significantly reduced after indomethacin plus HgCl₂ treatment, meanwhile the vasodilation produced by nitroprusside remained unchanged. Pretreatment with L-arginine (1 mM) did not prevent the vasoconstriction induced by HgCl₂, nor did it restore the ability of acetylcholine to produce vasodilation, and it did not alter the response to sodium nitroprusside. The possibility of HgCl₂'s actions mediated by the formation of free radicals was also investigated. The administration of 10 mM histidine significantly reduced the vasoconstrictor response if used before HgCl₂ treatment without improving the reduced vasodilation produced by acetylcholine. These results are consistent with the hypothesis that the vasoconstriction produced by HgCl₂ may be mediated by the formation of superoxide anions, stimulating the production of a COX-derived vasoconstrictor agent and by reducing the endothelial vasodilator activity. Received: 12 July 1999/Accepted: 30 December 1999     

Comparative Embryonic and Larval Developmental Responses of Estuarine Shrimp (<Emphasis Type="Italic">Palaemonetes pugio</Emphasis>) to the Juvenile Hormone Agonist Fenoxycarb

Grass shrimp (Palaemonetes pugio) were reared separately through both embryonic and total larval development during exposure to fenoxycarb at measured concentrations of <2.2 to 888 g L^–1. A fenoxycarb concentration of 888 g L^–1 significantly (p < 0.05) inhibited embryonic development to larval hatching and extended the embryonic developmental period from 11.9 to 12.7 days. Exposure to fenoxycarb concentrations 502 g L^–1 had no significant (p > 0.05) effect on complete embryonic development. Significantly fewer shrimp successfully metamorphosed to postlarvae when exposed through complete larval development to fenoxycarb concentrations 4 g L^–1. Larval development of grass shrimp was therefore >2 orders of magnitude more sensitive to this juvenile hormone agonist than was embryonic development. Viability of larvae developing in fenoxycarb was concentration dependent. Development beyond third zoeal stage was significantly inhibited at fenoxycarb concentrations 190 g L^–1, whereas development beyond fourth zoeal stage was inhibited by a concentration of 45 g L^–1. Fenoxycarb exposure of developing larvae did not alter either the duration of total larval development or the total number of larval stages before metamorphosis. Rearing of fenoxycarb-exposed embryos through larval development without further exposure had no significant effect on number of larval stages, larval development rate, or metamorphic success of larvae. Similarities in the sensitivity of grass shrimp larvae and mosquito larvae to fenoxycarb suggests that the use of a bioassay protocol measuring the metamorphic success of crustacean larvae would be a valuable adjunct to the hazard assessment of newly developed pesticides that target endocrine control of metamorphosis in insects and possibly other endocrine-disrupting xenobiotics as well.     

The effects of a simulated refinery effluent on the grass shrimp,Palaemonetes pugio

Duplicate static bioassays were conducted using a simulated refinery effluent on the grass shrimp (Palaemonetes pugio, Hippolyte sp.) with the LC-50 values recorded at 4-, 8-, 24-, 48-, and 96-hr intervals. The simulated refinery effluent contained phenol (0.10 mg/L), sulfide (0.17 mg/L), chromium (0.25 mg/L), ammonia (10 mg/L), No. 2 fuel oil (10 mg/L), and kaolinite (20 mg/L). This arbitrary reference mixture (ARM) contains approximately the concentration of compounds recommended by EPA for 1977. Of the six ARM components, No. 2 fuel oil was the most toxic followed in decreasing order by sulfide, ammonia, phenol, chromium, and kaolinite. Temperature was the most important environmental variable affecting short term toxicity of the ARM to the grass shrimp. Light intensity, photo-period, and salinity had no significant effect. There was no difference in sensitivity of grass shrimp collected from five locations along the gulf and eastern coasts of the United States. Similarly, there was no difference in the response of two grass shrimp genera,Palaemonetes andHippolyte to the ARM and there were no differences among the three species ofPalaemonetes tested. In comparing the sensitivities of the two genera of grass shrimp and the pinfish (Lagodon rhombroides) to the ARM, the grass shrimp were more sensitive. Supported by a contract from theAmerican Petroleum Institute.     

Differences in Prey Capture in Grass Shrimp, <Emphasis Type="Italic">Palaemonetes pugio,</Emphasis> Collected Along an Environmental Impact Gradient

The waterways and associated salt marshes along the western border of Staten Island, New York (Arthur Kill) have long been under environmental duress. Environmental threats include industrial and municipal discharges, oil spills, and possible leachate from landfills. These impacts are compounded due to the low flushing of this body of water. Grass shrimp, Palaemonetes pugio, inhabiting the Arthur Kill are, therefore, potentially at risk of exposure to metal and organic pollutants. Successful prey capture (of live brine shrimp, Artemia franciscana) was used to compare the relative health of shrimp collected from three sites along an environmental impact gradient. Study sites included a relatively unimpacted harbor (Great Kills Harbor, GK) and two creeks adjoining the Arthur Kill (Nassau Creek, NC, and Richmond Creek, RC). Shrimp originating from GK exhibited a rate of prey capture (6.3 prey h^–1) that was about two times greater (p < 0.05) than that of shrimp originating from a creek behind a series of landfills (RC, 3.2 prey h^–1). The rate of prey capture for shrimp collected from a creek impacted by historic smelting activities (NC) was intermediate (5.4 prey h^–1). Laboratory studies with shrimp from a pristine site (Tuckerton, NJ) exposed to RC conditions (i.e., sediment and water) for eight weeks indicate that reduced prey capture can be induced in healthy shrimp. Finally, video analysis suggests that reduced prey capture in RC shrimp may not be the result of less effort, but rather the combination of (1) 80% fewer (p < 0.05) prey being captured with a lunge type of attack and (2) a greater reliance (p < 0.05) on a less efficient grab type of foraging behavior (64% success rate for RC versus 87% success rate for GK; p = 0.058). These results indicate that sublethal toxicity in environmentally impacted populations can occur and that prey capture may be used to assay the relative health of field specimens. Additionally, impaired prey capture may have important implications for the energy flow within impacted environments.     

Acute and Chronic Toxicity of Buprofezin on <Emphasis Type="Italic">Daphnia Magna</Emphasis> and the Recovery Evaluation

The toxic effects of buprofezin on Daphnia magna after both chronic and acute exposures were evaluated according to OECD guidelines. A 48-h acute exposure of buprofezin resulted in daphnid immobility at an EC₅₀ of 0.44 mg/L. In a 14 days chronic exposure of buprofezin (0, 0.025, 0.05, 0.10 and 0.15 mg/L), the development and reproduction of daphnids were all significantly affected and the body length was more sensitive than other observed parameters. However, the adverse effects of buprofezin on parental daphnids can be passed on to their offspring and cannot be recovered in a short time.