Is Atyaephyra desmarestii a useful candidate for lethal and sub-lethal toxicity tests on pharmaceutical compounds?

Single and mixture toxicity tests on three pharmaceutical compounds, Diclofenac (DF), Ibuprofen (IB) and Carbamazepine (CBZ), were carried out with the freshwater shrimp Atyaephyra desmarestii. Lethal and sublethal responses were analyzed for single compounds. Lethal concentrations (LC50) obtained for each individual compound, after 96 h of exposure, were 6.3 mg L(-1) for DF, 13.3 mg L(-1) for IB and 94.3 mg L(-1) for CBZ. The selected sublethal endpoints of food ingestion, osmoregulatory capacity and respiration rates were not affected by the exposures to environmentally-relevant concentrations. Based on mortality data obtained, the predictive no effect concentration (PNEC) was calculated for each of the compounds, and compared with predicted environmental concentrations (PEC) reported in surface waters. The environmental risk of each compound was estimated as the ratio between PEC/PNEC, and indicated that IB could represent a medium risk in freshwater environments. Additionally, binary and ternary mixture toxicity assays of the selected compounds were carried out. The data obtained was applied to two predictive toxicity models: Concentration Addition (CA) and Independent Action (IA). Finally, risk assessment was estimated using risk quotients (RQ) for the compound mixtures based on EC50 and LC50 values.

Cd-induced apoptosis through the mitochondrial pathway in the hepatopancreas of the freshwater crab Sinopotamon henanense

Cd is one of the most common pollutants in the environment that also induces the apoptosis. To explore the mechanism of apoptosis in the hepatopancreas, freshwater crab S. henanense were treated with 0, 3.56, 7.12, 14.25, 28.49 and 56.98 mg/L Cd for 72 h. Apoptosis was noticeable in every treatment group and necrosis was observed clearly in the high concentration Cd groups. Classical apoptotic bodies were found by transmission electronic microscopy, which revealed chromatin condensation under nuclear membrane and mitochondrial membrane rupture. An increasing number of autolysosomes, damaged rough endoplamic reticulum and Golgi complex were observed as the Cd concentration increase. Brown colored apoptotic cells were detected by the TUNEL test in all Cd-treatment groups. The apoptosis index increased following the elevation of Cd concentration and got 32.9% in the highest Cd group. Caspase-9 and caspase-3 activities increased in the lower Cd treatment groups but no changes in the higher Cd concentration groups (comparing to the control group). The activity of caspase-8 did not change significantly. No significant change in the content of mitochondrial cytochrome c (cyt c) in Cd exposed groups except the decrease in the 56.98 mg/L group. In crabs treated with 3.56, 7.12 and 14.25 mg/L Cd, hyperpolarization of mitochondrial membrane potential (Δψ_m) significantly increased. These results implied that apoptosis in the hepatopancreas induced by Cd occurrs through the mitochondrial caspase-dependent pathway. However, whether there are other apoptotic pathways needs to be studied further.

The effects of cadmium exposure on the oxidative state and cell death in the gill of freshwater crab Sinopotamon henanense

We studied here the short-term toxicity effects of Cd on the oxidative state and cell death in the gill of freshwater crab Sinopotamon henanense. Crabs were exposed to Cd that resulted in Cd accumulation and a significant increase in the metallothionein (MT) level in the gill, but MT level increased disproportionally compared to the Cd accumulation with an extension of exposure time. Significant changes in the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were observed. An increase in the levels of reactive oxygen species (ROS) and lipid peroxidation (LPO) was detected that will cause oxidative stress. Histological abnormalities of the gills were discovered, including the expansion of gill cavity, a decrease in the numbers of connection of the upper and the lower of the gill lamellae and epithelial cells, and an increase in the number of hemocytes. The results of a TUNEL test and transmission electron microscope (TEM) showed that more gill cells had apoptotic characteristics after 48 h of Cd treatment compared to the control, but epithelial cell necrosis and inflammatory response appeared only after 72 h. It was concluded that (1) Cd induced the ROS production and accumulation through inhibiting antioxidant enzyme activities and exceeding the saturation values of MT binging; (2) Cd led to lipid peroxidation and histopathological alternations; and (3) Cd induced apoptotic response at short time exposure, followed by necrotic features and inflammatory reaction after longer time exposure.

Presence, fate and effects of the intense sweetener sucralose in the aquatic environment

Sucralose (1,6-dichloro-1,6-dideoxy-b-D-fructo-furanosyl 4-chloro-4-deoxy-a-D-galactopyranoside), sold under the trade name Splenda, has been detected in municipal effluents and surface waters in the United States and Europe. The environmental presence of sucralose has led to interest in the possibility of toxic effects in non-target species. This review presents an environmental risk assessment of sucralose based on available data concerning its presence, fate and effects in the environment. Sucralose, which is made by selective chlorination of sucrose, is a highly stable compound, which undergoes negligible metabolism in mammals, including humans, and displays a low biodegradation potential in the environment. This intense sweetener is highly soluble in water, displays a low bioaccumulation potential and a low sorption potential to soil and organic matter, and thus is predominantly present in the water column. The predicted environmental concentration (PEC) for sucralose, based on measured data in surface waters, was determined to be 10 μg/L. Aquatic toxicity studies using standardized, validated protocols used in regulatory decision making indicate that sucralose does not alter survival, growth and reproduction of aquatic organisms (such as plants, algae, crustaceans and fish) at concentrations >9000 times higher than those detected in the environment. Some studies, using non-standardized protocols, have reported behavioral and other non-traditional responses in aquatic organisms, but the relevance of these findings for assessing adverse effects on individuals and populations will require further investigation. In terms of traditional risk assessment, the proposed predicted no effect concentration for aquatic organisms (PNEC) was determined to be 0.93 mg/L, based on the lowest no effect concentration (NOEC) from a validated chronic study with mysid shrimp and an application factor of 100. The resultant PEC/PNEC quotient was determined to be well below 1 (PEC/PNEC=0.08), thus indicating a limited risk to the environment using traditional ecological risk assessment approaches.

Effects of glyphosate and polyoxyethylenamine on growth and energetic reserves in the freshwater crayfish Cherax quadricarinatus (Decapoda, Parastacidae)

Freshwater crayfish Cherax quadricarinatus have a high commercial value and are cultured in farms where they are potentially exposed to pesticides. Therefore, we examined the sublethal effects of a 50-day exposure to glyphosate acid and polyoxyethylenamine (POEA), both alone and in a 3:1 mixture, on the growth and energetic reserves in muscle, hepatopancreas and hemolymph of growing juvenile crayfish. Exposure to two different glyphosate and POEA mixtures caused lower somatic growth and decreased muscle protein levels. These effects, caused by both compounds interacting in the mixture, could also be synergistic because they were expressed even at the lowest concentration. The decrease in protein levels could be related to the greater use of other energy reserves. This hypothesis is supported by the decrease in muscle glycogen stores due to glyphosate exposure and the decrease in lipid reserves associated with exposure to POEA.

Genes are differentially expressed at transcriptional level of Neocaridina denticulata following short-term exposure to nonylphenol

To assess the toxicity of nonylphenol towards aquatic crustaceans, Neocaridina denticulata were exposed short-term to sublethal concentration (0.001-0.5 mg/L). Following treatment, differentially expressed genes were identified using suppression subtractive hybridization on samples prepared from whole specimens. There were 20 differentially expressed sequence tags that corresponded to known genes and could be divided into six functional classes: defence, translation, metabolism, ribosomal gene expression, respiration, and genes involved in the stress response. Using semi-quantitative RT-PCR, we found that 14 of the differentially expressed sequence tags significantly responded to nonylphenol, including six at a nominal concentration of 0.01 mg/L; among them, 12 genes were down-regulated. These results suggest that under non-lethal concentrations of nonylphenol, the polluted aquatic environment may still present a potential risk to N. denticulata.

Differential immune responses of the green neon shrimp (Neocaridina denticulate) to dipropyl phthalate

This study set out to understand the sublethal effect of xenobiotic phthalate esters (PAEs) on the relationship between the susceptibility of shrimp to bacterial infection and the immune response of the shrimp. Neocaridina denticulate were exposed to different concentrations of the PAE dipropyl phthalate (DPrP), and mortality and six immune parameters were measured on days 1, 3, 5, and 10 after exposure. On days 1 and 3 after exposure, shrimp exposed to 0, 1, 5, 10, and 50 mg/L of DPrP and challenged with Aeromonas veronii experienced 14% and 16%, 16% and 16%, 18% and 18%, 34% and 24%, and 38% and 26% mortality, respectively. On day 1, five immune parameters (acid phosphatase, AcP; β-glucuronidase, β-Glu; phenoloxidase, PO; superoxide dismutase, SOD; and haemocyanin mRNA) were significantly altered in the all of the groups treated with DPrP compared to the untreated shrimp and were elevated in the 10 mg/L- and 50 mg/L-treated groups. Beta-Glu activity and haemocyanin mRNA levels were significantly increased in a dose-dependent manner. These results suggest that the increased susceptibility of N. denticulate exposed to DPrP is short-term and may be related to the increased expression of DPrP-induced immune mediators.

Response and recovery of acetylcholinesterase activity in freshwater shrimp, Paratya australiensis (Decapoda: Atyidae) exposed to selected anti-cholinesterase insecticides

The toxicity of carbaryl, chlorpyrifos, dimethoate and profenofos to the freshwater shrimp, Paratya australiensis was assessed by measuring acetylcholinesterase (AChE) inhibition after 96h exposures. Shrimp exposed to these pesticides exhibited significant AChE inhibition, with mortality in shrimp corresponding to 70-90% AChE inhibition. The sensitivity of P. australiensis to the four pesticides based on AChE inhibition can be given as chlorpyrifos > profenofos > carbaryl > dimethoate. Recovery of AChE activity was followed in shrimp after 96 h exposures to carbaryl, chlorpyrifos and dimethoate. Recovery after exposure to the carbamate pesticide carbaryl was more rapid than for the two organophosphorus pesticides, chlorpyrifos and dimethoate. The slow recovery of depressed AChE activity may mean that affected organisms in the natural system are unable to sustain physical activities such as searching for food or eluding predators. To investigate the ecological significance of AChE inhibition, chemotaxis behaviour was assessed in shrimp exposed to profenofos for 24h. Abnormal chemotaxis behaviour in the exposed shrimp was observed at concentrations representing 30-50% AChE inhibition. A clear relationship existed between the depression of AChE activity and observed chemotaxis responses, such as approaching and grasping the chemoattractant source. These results suggest that in vivo toxicity tests based on this specific biomarker are sensitive and present advantages over conventional acute tests based on mortality. Behavioural studies of test organisms conducted in conjunction with measurement of AChE inhibition will provide data to clarify the toxic effects caused by sublethal chemical concentrations of anti-cholinesterase compounds.

Toxicity of selected pesticides to freshwater shrimp, Paratya australiensis (Decapoda: Atyidae): use of time series acute toxicity data to predict chronic lethality

Toxicity of six pesticides (carbaryl, chlorpyrifos, cypermethrin, dimethoate, diuron and fenarimol) to the freshwater shrimp, Paratya australiensis was assessed after 96 h exposures. Of the six pesticides tested, alpha cypermethrin was the most toxic to the shrimp followed by chlorpyrifos, carbaryl, dimethoate, fenarimol and diuron. Regression methods for predicting chronic toxicity (lethality) from acute lethality data with shrimp were developed and compared, and it was found that the log-log model gives the most reliable predictions of the probability of death as a function of extended exposure times. Based on this model, chronic toxicity (21 days) to P. australiensis was estimated as 0.0058 microg/L for alpha cypermethrin, 4.9 microg/L for carbaryl, 0.004 microg/L for chlorpyrifos, 89 microg/L for dimethoate, 240 microg/L for diuron and 1500 microg/L for fenarimol. Acute LC(10) values were also useful predictors of the chronic lethality. The log-log model was used to derive extrapolated chronic values that were compared to measured experimental chronic values for two fish species. The predictions of chronic toxicity based on acute toxicity data were found to give credible results for both fish species. These predictions of chronic toxicity can therefore be used in ecological risk assessments to fill in gaps with reasonable confidence where no measured estimates of chronic toxicity are available.

Effects of selenium on the antioxidant enzymes response of Neocaridina heteropoda exposed to ambient nitrite

The effects of dietary Selenium (Se) supplementation on muscle superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) activities and haemolymph superoxide anions (O(2)-) of Neocaridina heteropoda exposed to ambient nitrite were investigated. The results showed supplementation of Se in diet could enhance the resistance of shrimp to low concentration ambient nitrite. The results demonstrated that Se might have a potentially useful role as an effective antioxidant and resistance to aqueous nitrite in shrimp and the effect of the organic Se was better than that of the inorganic Se.

Dietary supplementation of mannan oligosaccharide improves the immune responses and survival of marron, Cherax tenuimanus (Smith, 1912) when challenged with different stressors

Three trials were conducted to determine the effects of mannan oligosaccharide (Bio-Mos ) on the immune responses of marron. In the first trial marron were challenged with Vibrio mimicus infection, in the second with NH3 exposure and in the third, the marron were exposed to air during a simulated live transportation trial. For V. mimicus infection and live transportation trials, marron (10.44 +/- 0.20 g and 4.44 +/- 0.20 g initial weights, respectively) were fed three different diets containing 0% (control diet), 0.2% and 0.4% Bio-Mos for 30 days and 112 days respectively before challenge, whereas for the NH3 exposure trial, marron (94 +/- 2.17 g initial weight) were reared with the control diet and 0.4% Bio-Mos diet for 42 days before exposure to NH3. Marron were examined for survival and total haemocyte count (THC), differential haemocyte count (DHC), haemolymph clotting time, bacteraemia and lysosomal membrane stability as indicators of immune responses during the course of the challenge. Survival of marron infected with bacteria and exposed to NH3, were significantly improved when fed Bio-Mos. THCs were significantly reduced in marron fed the control diet when they were infected with bacteria and subjected to live transportation while it remained unchanged in the marron fed the Bio-Mos supplemented diets. THCs of marron fed any of the diets were reduced when they were exposed to NH3 but the THCs were higher (P < 0.05) in marron fed Bio-Mos diets. Vibrio spp. in haemolymph of marron fed the control diet significantly increased when they were infected with V. mimicus and challenged with NH3 but it remained unchanged in the marron fed the Bio-Mos diets. Haemolymph clotting time was higher in marron fed the control diets when subjected to live transportation and 3 days of exposure to NH3. After 96 h infection marron fed the Bio-Mos diets had longer NRR time than those fed the control diet. All the findings demonstrated the ability of Bio-Mos to improve the survival, health status and immunity of marron under the bacterial infection and stress conditions caused by air and NH3 exposures.

Effects of river water and salinity on the toxicity of deltamethrin to freshwater shrimp, cladoceran, and fish

Deltamethrin is a pyrethroid insecticide used extensively to control invertebrate pests on cotton and other crops. It is acutely toxic to nontarget aquatic organisms, but existing toxicity data are mostly from toxicity tests using purified laboratory water that differs greatly from the turbid, high-conductivity rivers in the cotton-growing regions of Australia. The aim of this study was to determine whether the water quality variables conductivity, suspended particles, and dissolved organic matter alter the toxicity of deltamethrin to freshwater crustaceans and a fish. We tested three Australian native species: a cladoceran (Ceriodaphnia cf. dubia), a freshwater shrimp (Paratya australiensis), and larvae of the eastern rainbow fish (Melanotaenia duboulayi). Conductivity of the test solutions ranged from 200 to 750 microS/cm, but such changes did not modify the toxicity of deltamethrin to any of the test species. However, the toxicity of deltamethrin to C. cf. dubia and P. australiensis in river water was significantly decreased (1.8-fold to 6.3-fold reduction) compared to that in laboratory water. Variability in the toxicity data limited our ability to detect differences between laboratory and river water for M. duboulayi. Despite reductions in toxicity in natural waters, deltamethrin remained highly toxic [all L(E)C(50) values <0.26 microg/L] to all organisms tested; thus, further investigation of the hazard of deltamethrin is warranted.

Accumulation and elimination of chromium by freshwater species exposed to spiked sediments

The bioaccumulation and elimination capacity of chromium were examined in four freshwater species: the submersed aquatic plant Ceratophyllum demersum (Ceratophyllaceae), the oligochaete Limnodrilus udekemianus (Tubificidae), the crab Zilchiopsis collastinensis (Decapoda), and the fish Cnesterodon decemmaculatus (Poeciliidae). All of the species were exposed simultaneously to sediments spiked with Cr (K(2)Cr(2)O(7)) at different concentrations for 28 days, followed by 7 days without Cr to evaluate the concentration of residual Cr. We found that Cr accumulated in the tissues of all four species. The highest bioconcentration factor obtained for each species is as follows: C. demersum, 718.66 (+/-272.91); L. udekemianus, 172.55 (+/-80.8), Z. collastinensis, 67.72 (+/-35.4); C. decemmaculatus, 23.11 (+/-12.82), all at 28 days of exposure.

Lethal and sublethal effects of the pyrethroid, bifenthrin, on grass shrimp (Palaemonetes pugio) and sheepshead minnow (Cyprinodon variegatus)

This study investigated the lethal and sublethal effects of the pyrethroid insecticide bifenthrin on adult and larval grass shrimp, Palaemonetes pugio, and adult sheepshead minnows, Cyprinodon variegatus. The effects were determined by conducting 96-h aqueous static renewal tests and 24-h static tests with sediment. Oxidative stress biomarkers, lipid peroxidation, glutathione, and catalase were also assessed. The 96-h aqueous LC50 value for adult shrimp was 0.020 microg/L (95% CI: 0.015-0.025 microg/L) and for larval shrimp was 0.013 microg/L (95% CI: 0.011-0.016 microg/L). The 96-h aqueous LC50 for adult sheepshead minnow was 19.806 microg/L (95% CI: 11.886-47.250 microg/L). The 24-h sediment LC50 for adult shrimp was 0.339 microg/L (95% CI: 0.291-0.381 microg/L) and for larval shrimp was 0.210 microg/L (95% CI: 0.096-0.393 microg/L). The oxidative stress assays showed some increasing trends toward physiological stress with increased bifenthrin concentrations but they were largely inconclusive. Given the sensitivity of grass shrimp to this compound in laboratory bioassays, additional work will be needed to determine if these exposure levels are environmentally relevant.

Effects of Cadmium and Zinc on the feeding behaviour of two freshwater crustaceans: Atyaephyra desmarestii (Decapoda) and Echinogammarus meridionalis (Amphipoda)

Lethal and sublethal effects of Cadmium and Zinc on two freshwater crustaceans were investigated. The 96-h LC50 for Cadmium and Zinc were 42.20 microg l(-1) and 5.43 mg l(-1) for Atyaephyra desmarestii, and 36.17 microg l(-1) and 4.61 mg l(-1) for Echinogammarus meridionalis, respectively. An increase in metal concentrations at sublethal levels resulted in significant reductions of the feeding rate of both species. The LOECs in the chronic feeding assays for Zinc were 1.29 mg l(-1) for A. desmarestii and 0.4 mg l(-1) for E. meridionalis. For Cadmium the LOEC was 6.53 microgl(-1) for both species. The results suggest the potential use of these two crustacean species as test organisms in ecotoxicological tests. Feeding assays appear to be a rapid, cheap and effective tool to be used in biomonitoring studies of Portuguese freshwaters.

Branchial carbonic anhydrase activity and ninhydrin positive substances in the Pacific white shrimp, Litopenaeus vannamei, acclimated to low and high salinities

The Pacific white shrimp, Litopenaeus vannamei, acclimated to 30 ppt salinity, was transferred to either low (15 and 5 ppt), or high (45 ppt) salinity for 7 days. Hemolymph osmolality, branchial carbonic anhydrase activity, and total ninhydrin-positive substances (TNPS) in abdominal muscle were then measured for each condition. Hemolymph osmotic concentration was regulated slightly below ambient water osmolality in shrimp acclimated to 30 ppt. At 15 and 5 ppt, shrimp were strong hyper-osmotic regulators, maintaining hemolymph osmolality between 200 and 400 mOsm above ambient. Shrimp acclimated to 30 ppt and transferred to 45 ppt salinity were strong hypo-osmotic and hypo-ionic regulators, maintaining hemolymph osmolality over 400 mOsm below ambient. Branchial carbonic anhydrase (CA) activity was low (approximately 100 micromol CO(2) mg protein(-1) min(-1)) and uniform across all 8 gills in shrimp acclimated to 30 ppt, but CA activity increased in all gills after exposure to both low and high salinities. Anterior gills had the largest increases in CA activity, and levels of increase were approximately the same for low and high salinity exposure. Branchial CA induction appears to be functionally important in both hyper- and hypo-osmotic regulations of hemolymph osmotic concentrations. Abdominal muscle TNPS made up between 19 and 38% of the total intracellular osmotic concentration in shrimp acclimated to 5, 15, and 30 ppt. TNPS levels did not change across this salinity range, over which hemolymph osmotic concentrations were tightly regulated. At 45 ppt, hemolymph osmolality increased, and muscle TNPS also increased, presumably to counteract intracellular water loss and restore cell volume. L. vannamei appears to employ mechanisms of both extracellular osmoregulation and intracellular volume regulation as the basis of its euryhalinity.

Calcium movements during pigment aggregation in freshwater shrimp chromatophores

Pigment granule migration within crustacean chromatophores provides an excellent model with which to investigate cytoplasmic movements, given the antagonistic, neurosecretory peptide regulation of granule translocation, and the absence of innervation in these large, brightly colored cells. Red pigment-concentrating hormone (RPCH) induces pigment aggregation in shrimp chromatophores via an increase in intracellular Ca2+; however, how this increase is brought about is not known. To examine the putative Ca2+ movements leading to pigment translocation in red, ovarian chromatophores of the freshwater shrimp, Macrobrachium olfersii, this study manipulates intra- and extracellular Ca2+ employing ER Ca2+-ATPase inhibitors, ryanodine-sensitive, ER Ca2+ channel blockers, and EDTA/EGTA-buffered A23187/Ca2+-containing salines. Our findings reveal that during pigment aggregation, cytosolic Ca2+ apparently increases from an intracellular source, the abundant SER, loaded by the SERCA and released through ryanodine-sensitive receptor/channels, triggered by capacitative calcium influx and/or calcium-induced calcium release mechanisms. Aggregation also depends on external calcium, which may modulate RPCH/receptor coupling. Such calcium-regulated pigment movements form the basis of a complex system of chromatic adaptation, which confers selective advantages like camouflage and protection against ultra-violet radiation to this palaemonid shrimp.

Impact of waterborne copper on the structure of gills and hepatopancreas and its impact on the content of metallothionein in juvenile giant freshwater prawn Macrobrachium rosenbergii (Crustacea: Decapoda)

This study aims to elucidate both the impact of copper on the structure of the gills and hepatopancreas and the induction of metallothionein (MT) during waterborne copper exposure in juvenile Macrobrachium rosenbergii. Structural observations were performed with light microscopy, and the MT titrations were performed with the cadmium saturation assay. The structural changes that occurred in the gills and hepatopancreas appeared to result from copper accumulation, and the degree of damage observed in both tissues was relevant to the elevated waterborne copper concentration. Exposure to copper concentrations ranging from 0.01 mg/L to 0.4 mg/L for 7 days resulted in profound structural changes including the accumulation of hemocytes in the hemocoelic space; swelling and fusion of the lamellae; abnormal gill tips; and hyperplastic, necrotic, and clavate-globate lamellae in the gills. Similarly, hemocytic infiltration in the interstitial sinuses, an increased number of hemocytes, thickening and ruptures of the basal laminae, and necrosis of the tubules were observed in the hepatopancreas. The MT measurements showed no significant differences in MT contents between the control group and the group treated with 0.01 mg/L waterborne copper. The maximum MT content was observed at the level of 0.4 mg/L waterborne copper.

Osmoregulation and tissue water regulation in the freshwater red crab Dilocarcinus pagei (Crustacea, Decapoda), and the effect of waterborne inorganic lead

Inorganic lead has been measured in high concentrations in certain streams in Brazil. This study has evaluated the osmoregulatory effects of lead on the native freshwater red crab Dilocarcinus pagei. In order to probe its osmoregulatory and tissue volume regulatory capabilities and how it would be affected by lead, the crab has been submitted to individual and combined salt and chemical stresses (Pb2+). Male crabs were exposed for 10 days to either: (1) control (freshwater, FW), (2) brackish water of salinity 15 (BW), (3) inorganic lead in freshwater (FWPb), and (4) inorganic lead in brackish water (BWPb), 2.7 mgPb/L. In vivo, whole crabs lost weight transiently when exposed to Pb2+, both in FW and in BW. Haemolymph osmolality and ion concentrations increased and remained elevated upon exposure of crabs to BW, with or without Pb2+, showing a trend to hyper-conformation. In vitro, muscle weight decreased in isosmotic conditions upon exposure to Pb2+. Na+, Cl-, and ninhydrin positive substances (NPS) were increased in muscle exposed to hyperosmotic saline, well above what would be expected from simple efflux of water, suggesting a partial regulatory volume increase (RVI) capacity. This partial RVI involves the Na+, K+, 2Cl- -cotransporter and the Na+/H+ exchanger on Na+ and Cl- uptake, as judged from further decreases in muscle weight in the presence of the respective inhibitors. A breakdown of proteins into NPS seems to follow the uptake of inorganic ions. Pb2+ has affected water and ion movements in D. pagei both in the whole animal and in the isolated tissue. This study has highlighted the relevance of evaluating tissue volume regulation in aquatic animals confronted with metal polluted waters.

Reproduction obstacles for the female green neon shrimp (Neocaridina denticulata) after exposure to chlordane and lindane

The purpose of this study was to investigate the effects of chlordane and lindane on reproduction obstacles and endocrine disruption in female green neon shrimp (Neocaridina denticulata). Individuals of N. denticulata, a common inhabitant of freshwater systems in Taiwan, was exposed to different levels of chlordane (1 and 10 ngl(-1)) and lindane (0.1 and 1 microgl(-1)). The reproductive ability and reproductive hormone levels were observed after exposure. According to our findings, an increase in estrogen, induction of a vitellogenin-like protein, and changes in reproductive performance were observed in both chlordane- and lindane-treated shrimp. Thus, it was concluded that chlordane and lindane may cause some reproduction obstacles and disruption of endocrine functions in N. denticulata.

Behavioral changes and acute toxicity to the freshwater shrimp Atyaephyra desmaresti Millet (Decapoda: Natantia) from exposure to acid mine drainage

Short-term 48 h laboratory bioassays with water from an acid mine drainage (AMD: pH 3.3, 4.4, 5.0, 5.5, 6.4, control) and water from an arsenic containing reservoir were performed with the freshwater shrimp Atyaephyra desmaresti Millet, validated in situ and compared to acidified control water (ACID). Behaviour, mortality and time to death were monitored with the Multispecies Freshwater Biomonitor (MFB). The shrimps had equal 24 h-LC50s at pH 4 in AMD and ACID. However, after 48 h AMD proved more toxic (48 h-LC50 at pH 5.2) than ACID (48 h-LC50 at pH 4.5). Stress behaviour in AMD consisted at pH < or = 6.4 of a pH-dependent decrease in activity, with disappearance of circadian rhythmicity, and at pH 4.4 a clear increase of ventilation. At pH 5.5 bioaccumulation of metals was higher and locomotion lower than at pH 5.0. In ACID, only at pH < or = 4.4 locomotion became abated and arythmic. Locomotion in the field was equal or higher compared to the laboratory, whereas the ventilation was higher in the laboratory. A. desmaresti is a valuable species to be used in short term behavioural bioassays of AMD in Europe.

Immunostimulation of white shrimp (Litopenaeus vannamei) following dietary administration of Ergosan

Ergosan an algal product containing 1% alginic acid, developed for use in aquaculture and reported to have immunomodulatory activity, was administered orally to intermoult adult white shrimp (Litopenaeus vannamei) for 15 days. Examination of haemolymph proteins using SDS-PAGE did not reveal any obvious differences between control and Ergosan treated shrimp. Similarly, total haemocyte counts were found to be roughly equivalent for both the control and experimental samples. However, differential analysis of haemocyte populations revealed marked changes in terms of the relative levels of hyaline, semi-granular, and particularly granular haemocytes between the two groups. Moreover, enhancement of the in vitro antimicrobial activity of haemolymph towards two shrimp pathogenic Vibrio isolates was recorded for shrimp fed with Ergosan. Finally, shrimp fed with Ergosan showed a significant increase in relative growth when compared with control groups.

The effect of lead on the metabolic and energetic status of the Yabby, Cherax destructor, during environmental hypoxia

The concomitant effects of Pb and hypoxia on respiration and muscle energy status were examined in the freshwater crayfish Cherax destructor to determine if Pb intoxication exacerbated the effects of hypoxia. C. destructor, either intoxicated for 14 days with 0.5 mgL(-1)Pb, or from Pb-free control conditions, were subjected to progressive hypoxia at -2.7 kPah(-1) to a O2 partial pressure in the water (PwO2) of 1.33 kPa. This hypoxia was then sustained for 3 h. Pb-exposure reduced O2-uptake (MO2) at all PwO2 above 1.33 kPa but without any saving in ventilation, implying that Pb either unlinked ventilation from actual O2 requirements or rendered O2 transfer across the gill less efficient. Hypoxia alone induced no change in the adenylate energy charge (AEC), total adenylate (TAN), ATP/ADP ratio or in the equilibrium constant for adenylate kinase K'(ADEN), apparently due to protection of ATP levels by arginine phosphate. Under maximal hypoxia (PwO2=1.33 kPa) the Pb-exposed crayfish increased muscle ADP by 73% (tail) and 158% (chelae) but without any change in AMP, ATP or TAN. Thus, AEC declined (chelae AEC=0.71; tail AEC=0.85), as did the ATP/ADP ratio and K'(ADEN). L-Lactate increased in the muscle tissues of control but not Pb-exposed crayfish, consistent with a lowered O2 requirement in the Pb-exposed animals. The Pb intoxication slowed respiration and probably glycolysis, possibly altering the [ATP]:[ADP] equilibrium concentrations for adenylate kinase K'(AK). Lowered MO2 during severe hypoxia slows oxidative phosphorylation and ADP accumulation could occur as non-utilised substrate and may reflect a transient disequilibrium. During this time ATP levels were protected by arginine phosphate. AEC is sensitive to Pb in hypoxic crayfish but the changes have low importance for the energetic competence of the crayfish. During sustained hypoxia the crayfish recovered their energy status regardless of the Pb-exposure and this was, therefore, not a feature of Pb intoxication. Consequently, the ADP was recovered into the ATP pool of the hypoxic crayfish, and demand on arginine phosphate relieved. The Pb exposure did not otherwise exacerbate the effect of sustained hypoxia and C. destructor appeared to cope well with Pb intoxication, apparently by a specific Pb-induced hypometabolism separate from hypoxic response. Lowered metabolism as a survival response has limitations in the longer term and the implications for crustaceans generally warrant further study.

Effects of chlordane and lindane on testosterone and vitellogenin levels in green neon shrimp (Neocaridina denticulata)

The purpose of this study was to investigate the acute toxicity of chlordane and lindane as well as their endocrine disruption effect on green neon shrimp (Neocaridina denticulata), a common habitant in freshwater system of eastern Asia and Hawaii. First, the organisms were exposed to chlordane and lindane to estimate the 96-h LC(50)(96-h median lethal concentration). Then, levels of testosterone and vitellogenin in hemolymph of N. denticulata after exposure to sublethal concentrations of chlordane (1 ng/L and 10 ng/L) and lindane (0.1 microg/L and 1 microg/L) were also examined. The 96-h LC(50) values obtained from the results of acute exposure were 127.03 (130.11-122.35) ng/L and 9.36 (8.00-10.96) microg/L for chlordane and lindane, respectively. Furthermore, reductions of testosterone concentration were observed in both chlordane- and lindane-treated shrimps, whereas induction of vitellogenin-like protein was only apparent in chlordane-treated shrimps. Thus, it is concluded that chlordane and lindane may probably show some disruption endocrine functions on N. denticulata.