Effects of copper and zinc on growth, feeding and oxygen consumption of Farfantepenaeus paulensis postlarvae (Decapoda: Penaeidae)

Species distribution models to predict the impacts of environmental disasters on shrimp species of economic interest

Here, we used distribution models to predict the size of the environmentally suitable area for shrimps of fishing interest that were impacted by the tailing plume from the collapse of the Fundão Dam, one of the largest ecological disasters ever to occur in Brazil. Species distribution models (SDMs) were generated for nine species of penaeid shrimp that occurred in the impacted region. Average temperature showed the highest percentage of contribution for SDMs. The environmental suitability of penaeids varied significantly in relation to the distance to the coast and mouth river. The area of environmental suitability of shrimps impacted by tailings plumes ranged from 27 to 47 %. Notably, three protected areas displayed suitable conditions, before the disaster, for until eight species. The results obtained by the SDMs approach provide crucial information for conservation and restoration efforts of coastal biodiversity in an impacted region with limited prior knowledge about biodiversity distribution.

Effects of post-fire contamination in sediment-dwelling species of riverine systems

Wildfires are an important environmental problem in forested watersheds and can significantly alter water quality. Besides the reported ecotoxicological effects on pelagic species, the accumulation of post-fire contaminants in river sediments can also impair the benthic species. In this study, three sediment-dwelling species, Chironomus riparius, Atyaephyra desmarestii and Echinogammarus meridionalis, with different sensitivities, habitats, behaviours and/or feeding strategies, were exposed to water and sediments, in in-situ and in laboratory. Four sites were selected in a partially burnt basin (Alfusqueiro river basin), within and upstream the burnt area. The sites within the burnt area showed higher metal burden in both water and sediment, as well as changes in water physico-chemistry, consistently with the typical effects of incoming post-fire runoff. Both in-situ and laboratory exposures to water and sediments affected by the wildfire induced post-exposure feeding inhibition in the three tested macroinvertebrates. In fact, laboratory and field bioassays have produced generally consistent post-exposure feeding inhibition responses, but the most impactful response could be recognised after in-situ bioassays at the river site within the burnt area, where the species respond to the physico-chemical fluctuations during the exposure period. This comparative perspective supports the importance of using in-situ bioassays as a more realistic approach when dealing with complex and intermittent natural samples such as those affected by post-fire runoff. Overall, our results reinforce the awareness about the negative effects of wildfires on benthic biota, with significant feeding depression and consequent reduction in the available energy budget to ensure successful detoxification, growth and reproduction signalling potential trophic and functional disruption at the ecosystem level. In addition, the duality conditions of sediments as a sink and source of contaminants reinforce concerns, as the exposure of benthic organisms may persist in the long term, even after runoff income ceases due to the resuspension of contaminated sediments.

Effects of Cd accumulation on cutworm Spodoptera litura larvae via Cd treated Chinese flowering cabbage Brassica campestris and artificial diets

By exposing herbivorous cutworm Spodoptera litura (Lepidoptera: Noctuidae) larvae to Cadmium (Cd) stress via Cd treated cabbages Brassica campestris and artificial diets, we investigated effects of Cd accumulation in larvae on their survival and food utilization. The results showed that Cd transferred from soils contaminated with different Cd concentrations through cabbages-larvae, and be mainly accumulated in larvae guts. There was a dose-response relationship between Cd accumulations in larvae cuticle, head, guts and Cd concentrations in artificial diets, and the highest one was found in the guts, regardless of generations. High Cd stress (10 mg kg^-1 Cd in soil, 40.6, 81.2 mg kg^-1 Cd in artificial diets) had inhibited effects on larvae growth and food utilization, whereas low Cd stress (Lvbao 701 planted in 2.5 mg kg^-1 Cd soil, 4.06 mg kg^-1 Cd in artificial diets) showed stimulated effect. Cd accumulations in the guts were significantly negative correlated with efficiency of conversion of ingested food (ECI) and relative growth rate (RGR) of larvae feeding on Cd treated diets or cabbages while were significantly positive correlated with relative consumption rate (RCR). Therefore, after S. litura larvae feed on Cd treated natural food or artificial diets, Cd could be transferred to different tissues, and mainly accumulated in the guts, which significantly affected growth and food utilization. Additionally, Cd stress via Cd treated artificial diets presented less detrimental effects on S. litura larvae than via Cd treated cabbages.

Acute toxic effects of zinc and mercury on survival, standard metabolism, and metal accumulation in juvenile ridgetail white prawn, Exopalaemon carinicauda

Ridgetail white prawn (Exopalaemon carinicauda) is widely distributed in Chinese coastal zones, especially in the Yellow Sea and Bohai Sea. It is not only considered as an important economic species in China, but also taken as a potential indicator species for the environmental pollution in the estuaries. At present, the responses of this species to environmental toxicants, including trace metal are not well understood. In this study, the acute toxic effects of zinc (Zn) and mercury (Hg) on the survival, oxygen consumption, ammonia-N excretion, and metal accumulation were investigated in the juveniles of E. carinicauda. The median lethal concentrations (LC₅₀) of Zn were 76.4, 44.0, 30.2, and 17.2mg/L, respectively, after the juveniles were exposed in for 24, 48, 72, and 96h, and the LC₅₀ of H_g was 0.212, 0.096, 0.084, and 0.065mg/L under the same exposure duration. The juveniles decreased the oxygen consumption by 51.4%, and increased ammonia-N excretion by 129% when they were exposed in Zn at the concentration of 76.4mg/L compared with their controls without Zn exposure, therefore the O:N ratio decreased by 82.9% compared with the control. Hg exposure with the concentration of 0.212mg/L caused the inhibition of oxygen consumption by 48.1% and increasement of ammonia-N excretion by 161%, and the atomic ratio of consumed oxygen to excreted ammonia-nitrogen (O:N ratio) decreased by 80.6% in the juveniles in comparison with the control. A concentration-dependent accumulation of heavy metals was observed in the gills, hepatopancreas and muscles of the experimental animals, with a maximum accumulation of 16.3 folds for Zn and 72.8 fold for Hg in the gills of the juveniles after 24h exposure. The data obtained from the present study would provide useful information for help further understanding on the toxicological responses of this species to trace metals.

Effects of Copper on Hemocyte Apoptosis, ROS Production, and Gene Expression in White Shrimp Litopenaeus vannamei

Copper, a common chemical contaminant in aquatic environment, is known to be toxic to aquatic life at high concentrations. In the present study, we evaluated the apoptotic cell ratio and ROS production in hemocytes of the white shrimp Litopenaeus vannamei exposed to 1 or 5 mg L^-1 Cu for 0, 3, 6, 12, 24, and 48 h. The expression changes of antioxidant biomarker genes, i.e., copper-zinc superoxide dismutase (Cu-Zn SOD) and catalase (CAT), apoptosis-related genes, i.e., caspase-3 and inhibitor of apoptosis protein (IAP), and a specific biomarker gene of heavy metal pollution, i.e., metallothionein (MT), were also determined in hemocytes. Significant increases in ROS production were observed in both treatment groups at each time points. The apoptotic cell ratios were significantly increased at 6-48 h among shrimp exposed to 1 mg L^-1 Cu and at each time points in 5 mg L^-1 Cu group. These results indicated that Cu would induce oxidative stress and apoptosis in the hemocyte of L. vannamei. Quantitative real-time PCR analysis revealed that the relative expression levels of Cu-Zn SOD, CAT, caspase-3, IAP, and MT were upregulated in a dose-dependent and time-dependent manner, suggesting the involvement of these genes in stress response against Cu exposure.

Physiological effects of essential metals on two detritivores: Atyaephyra desmarestii (Millet) and Echinogammarus meridionalis (Pinkster)

Freshwater ecosystems are essential for humans; however, input of several types of contamination has led to the degradation of these ecosystems. Thus, it is urgent to assess their health to allow actions for prevention and remediation. The level of trace metals can be enhanced by natural or anthropogenic sources. Essential metals, such as copper and zinc, become toxic when present in the environment above threshold concentrations. To evaluate the physiological effects of these 2 essential metals for 2 freshwater detritivores, the shrimp Atyaephyra desmarestii and the amphipod Echinogammarus meridionalis, acute tests were performed. Forty-eight hour median lethal concentration (LC50) values were estimated for these species using static bioassays with copper and zinc. Sublethal assays for both metals with several phases were also done to evaluate the effects on feeding behavior. The LC50 values of copper for the shrimp A. desmarestii and amphipod E. meridionalis were 0.128 mg/L and 0.050 mg/L and those of zinc were 7.951 mg/L and 11.860 mg/L, respectively. The results indicated that copper is more toxic to both species. Only E. meridionalis showed deleterious effects of copper on feeding rate. Zinc showed some tendency for feeding inhibition in both species. Environ Toxicol Chem 2016;35:1442-1448. © 2015 SETAC.

Impaired regulation of divalent cations with acute copper exposure in the marine clam Mesodesma mactroides

The mechanism of copper (Cu) toxicity in marine invertebrates remains unclear. Therefore, marine clams (Mesodesma mactroides) were exposed (96h) to a concentration of dissolved Cu (1.6μmolL(-1)) inducing 10% mortality in sea water (30ppt). After in vivo exposure, tissue Cu accumulation (hemolymph, gill and digestive gland); hemolymph ionic (Na(+), K(+), Mg(2+) and Ca(2+)) and osmotic concentrations; tissue (gill and digestive gland) ionic concentration, enzyme (Na(+),K(+)-ATPase and carbonic anhydrase) activity, and oxygen consumption; and whole-body oxygen consumption were analyzed. Succinate dehydrogenase activity was evaluated in mitochondria isolated from gills and digestive gland and exposed (1h) in vitro to different concentrations of dissolved Cu (0.8, 7.7 and 78.7μmolL(-1)). In vivo exposure induced Cu accumulation in hemolymph, gills and digestive gland; increased Mg(2+) and decreased Ca(2+) concentration in hemolymph; decreased Mg(2+) concentration, increased Na(+),K(+)-ATPase activity and reduced carbonic anhydrase activity in gills; decreased Mg(2+) concentration, increased Ca(2+) concentration and increased Na(+),K(+)-ATPase activity in digestive gland; and reduced gill, digestive gland and whole-body oxygen consumption. Succinate dehydrogenase activity was inhibited after in vitro exposure to 78.7μmolL(-1) Cu. These findings indicate that Cu is an ionoregulatory toxicant in the marine clam M. mactroides. However, toxicity is related to disturbances in regulation of divalent cations (Mg(2+) and Ca(2+)) without effect on regulation of major monovalent cations (Na(+) and K(+)), as opposed to that observed in osmoregulating invertebrates exposed to Cu. However, other mechanism(s) of toxicity cannot be ruled out. Future studies must be performed to evaluate the consequence of the Cu-induced respiratory disturbances observed in M. mactroides.

Feeding preferences of two detritivores related to size and metal content of leaves: the crustaceans Atyaephyra desmarestii (Millet) and Echinogammarus meridionalis (Pinkster)

The equilibrium of the structure and functioning of freshwater ecosystems is dependent of detritivores that link all the other functional groups. The preference for feeding leaves with different diameters (particle size) and leaves with metal contamination (several concentrations of the essential metals copper and zinc) were determined for two detritivores, the decapod Atyaephyra desmarestii and the amphipod Echinogammarus meridionalis. Several no-choice and multi-choice assays were done to determinate which leaf diameter the amphipod and the decapod species would eat when they had or not had alternatives available and include a set of dual-choice assays with contaminated and uncontaminated foods. No significant preference was shown by either species relative to the diameter of leaves, either on no-choice or multi-choice assays. The presence of essential metals on food did not had any influence on the feeding choice of these organisms over the concentration range studied. Both showed no preference on ingesting food spiked with these essential metals, except E. meridionalis which preferred ingesting leaves with 2.19 μg.l(-1) of copper instead of uncontaminated leaves. For further works, despite no preference for leaves with a certain diameter, the leaves with 0.70 cm (0.385 cm(2)of area) and with 0.50 cm (1.767 cm(2) of area) should be used for A. desmarestii and E. meridionalis, respectively. Furthermore, to maintain E. meridionalis, the diet should include some percentage of copper in order to accomplish metabolic needs.

Effects of copper exposure on the energy metabolism in juveniles of the marine clam Mesodesma mactroides

In freshwater osmoregulating mollusks, Cu can cause toxicity by inducing ionoregulatory disturbances. In mussels, it inhibits the activity of key enzymes involved in Na(+) uptake and consequently induces ionic and osmotic disturbances. In snails, Cu induces disruption of the Ca(2+) homeostasis leading to effects in shell deposition and snail growth. However, the mechanisms involved in Cu toxicity in osmoconforming sweater mollusks remain unclear. Recent findings from our laboratory have suggested that Cu toxicity in marine invertebrates can be associated with both ionic and respiratory disturbances. In the present study, metabolic changes induced by waterborne Cu exposure were evaluated in the osmoconforming clam Mesodesma mactroides, a bivalve species widely distributed along the South American sandy beaches. Juvenile clams were kept under control conditions (no Cu addition in the water) or acutely (96h) exposed to Cu (96-h LC10=150μgL(-1)) in artificial seawater (30ppt). ATP, protein, lipid, glycogen and glucose contents were analyzed in gills, digestive gland, pedal muscle and hemolymph. Dinucleotide (NAD(+) and NADH) content was also analyzed in gills, digestive gland and pedal muscle while pyruvate and lactate content was determined in pedal muscle and hemolymph. In all tissues analyzed, Cu exposure did not affect ATP content and NAD(+)/NADH ratio, except in the hemolymph, where a decrease in ATP content was observed. These findings indicate that clam cells, except those from hemolymph, were able to maintain a constant level of free energy. A significant increase in total protein content was observed in the digestive gland, which could be a compensatory mechanism to counteract the higher level of protein oxidation previously observed in M. mactroides exposed to Cu under the same experimental conditions. Finally, reduced glucose content in the pedal muscle paralleled by increased lactate content in the pedal muscle and hemolymph was observed in Cu-exposed clams. Overall, these findings indicate that Cu exposure is leading to an increased reliance upon the anaerobic energy production to maintain the overall cellular ATP production in the clam M. mactroides.

Acute effects of cadmium and copper on survival, oxygen consumption, ammonia-N excretion, and metal accumulation in juvenile Exopalaemon carinicauda

Ridgetail white prawn (Exopalaemon carinicauda), a commercially important species in China, is a potential candidate for evaluating impairments caused by environmental pollutants in coastal and estuarine areas. The main purpose of the present study was to investigate the acute effects of cadmium (Cd) and copper (Cu) on survival, oxygen consumption, ammonia-N excretion, and metal accumulation in E. carinicauda. The feasibility of using this species for pollution monitoring was also evaluated. Results showed that the median lethal concentrations (LC50) for 24h, 48h, 72h, and 96h were 0.66mg/L, 0.379mg/L, 0.343mg/L, and 0.258mg/L for Cd, and 0.932mg/L, 0.748mg/L, 0.725mg/L, and 0.712mg/L for Cu. Cd exposure (0.66mg/L) caused an inhibition in oxygen consumption of 21.1 percent and an increase in ammonia-N excretion of 47.1 percent, thereby decreasing the atomic ratio of oxygen consumed to nitrogen consumed (O:N ratio) of 46.32 percent relative to the control. Cu exposure (0.932mg/L) also resulted in an inhibition in oxygen consumption of 34.8 percent and a decrease in the O:N ratio of 23.9 percent in relation to the control, but the ammonia-N excretion was not influenced by the Cu exposure. Concentration-depended accumulation was observed in the experimental animals, which a maximum of 244.8 folds and 1.1 folds increase of mental concentration was measured upon exposure to 24h LC50 of Cd and Cu for 24h, respectively. The change in O:N ratio indicated an alteration in energy utilization. Based on its sensitivity to heavy metals and its availability all year round, E. carinicauda can be used as a test organism to monitor for metal pollution.

Influence of copper pre-exposure on biochemical responses of the sea anemone Bunodosoma cangicum to changes in oxygen availability

The influence of copper on the ability of the intertidal sea anemone Bunodosoma cangicum to cope with reactive oxygen species generation associated with changes in oxygen availability was evaluated. Sea anemones were kept under control condition or pre-exposed (96 h) to dissolved copper (6.1 μg ± 2.7 μg/L) and then subjected to a 6-h period of hypoxia (0.5mg O₂/L) followed by a 6-h period of re-oxygenation (7.5mg O₂/L). Antioxidant capacity against peroxyl radicals (ACAP), superoxide dismutase (SOD) activity, reduced glutathione (GSH) concentration, lipid peroxidation (LPO) level, and ATP concentration were evaluated. Control sea anemones showed variations in SOD and LPO while copper pre-exposed sea anemones displayed changes in ACAP, GSH, LPO and ATP. However, no clear pattern of change over time was observed. ACAP was lower in copper pre-exposed sea anemones than in the control ones during hypoxia and recovery. SOD activity was increased during hypoxia and reduced shortly after recovery in control sea anemones. GSH concentration was higher in copper pre-exposed sea anemones than in the control ones in all experimental conditions. The LPO level increased shortly after recovery in both groups of sea anemones, being higher in control sea anemones than in copper pre-exposed ones. ATP concentration showed transient changes in copper pre-exposed sea anemones, being lower in these sea anemones than in control ones during recovery. These findings suggest that B. cangicum possess mechanisms to prevent oxidative stress generated by changes in oxygen availability associated with the tidal cycle, which can be disturbed by pre-exposure to copper.

Food utilization and growth of cutworm Spodoptera litura Fabricius larvae exposed to nickel, and its effect on reproductive potential

Food utilization and growth of the 5th and 6th instar Spodoptera litura Fabricius larvae, and its effect on reproduction potential was evaluated by feeding larvae diets with different doses of Ni for 3 generations. Dose-dependent relationships between Ni levels and food consumption and growth were variable with different larval developmental period and Ni exposure duration. RCR, AD and RGR of the 6th instar larvae were much more affected by Ni exposure than those of 5th instar larvae, and the effects were strongest in the 3rd generation. It was found that RCR was significantly stimulated after 1 and 20 mg kg(-1) Ni exposure, while AD was significantly inhibited after 1, 5, 10 and 40 mg kg(-1) Ni exposure. However, lower levels of Ni (≤5 mg kg(-1)) significantly increased and higher levels of Ni (≥10 mg kg(-1)) significantly decreased RGR. In 3 successive generations, 10 mg kg(-1) Ni significantly increased the ECI and ECD of the 5th instar larvae, and 5 mg kg(-1) Ni significantly increased the ECD of the 6th instar larvae. However, ECD were all significantly inhibited with 20 mg kg(-1) Ni exposure. Results also revealed that durations of larvae were shortened at low levels of Ni, but extended at high levels of Ni. Fecundity was inhibited by the highest Ni doses in each generation, while improved by low Ni doses in the 3rd generation. Hatching rates in all treatments were significantly decreased in a Ni dose-dependent manner. Study indicated that effects of Ni on these parameters were predominant with the increasing Ni exposure period.

Biomarkers of waterborne copper exposure in the guppy Poecilia vivipara acclimated to salt water

The responses of a large suite of biochemical and genetic parameters were evaluated in tissues (liver, gills, muscle and erythrocytes) of the estuarine guppy Poecilia vivipara exposed to waterborne copper in salt water (salinity 24 ppt). Activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione reductase, and glutathione S-transferase), metallothionein-like protein concentration, reactive oxygen species (ROS) content, antioxidant capacity against peroxyl radicals (ACAP), and lipid peroxidation (LPO) were evaluated in liver, gills, and muscle. Comet assay score and nuclear abnormalities and micronucleated cell frequency were analyzed in peripheral erythrocytes. The responses of these parameters were evaluated in fish exposed (96 h) to environmentally relevant copper concentrations (5, 9 and 20 μg L⁻¹). In control and copper-exposed fish, no mortality was observed over the experimental period. Almost all biochemical and genetic parameters proved to be affected by waterborne copper exposure. However, the response of catalase activity in liver, ROS, ACAP and LPO in muscle, gills and liver, and DNA damages in erythrocytes clearly showed to be dependent on copper concentration in salt water. Therefore, the use of these parameters could be of relevance in the scope of biomonitoring programs in salt water environments contaminated with copper.

Effects of metal burden and food avoidance on the transfer of metals from naturally contaminated prey to a marine predator Nassarius siquijorensis

Nassarid snails are important opportunistic scavengers widely found in marine intertidal shores and trophic transfer is a predominant source of metal accumulation in these species, thus there is a significant need to understand the controls of metal trophic transfer. In the present study, we took advantage of a severely contaminated estuary and collected two prey organisms (oysters Crassostrea angulata and barnacles Fistulobalanus albicostatus) with different contamination histories. These naturally contaminated prey were fed to a marine neogastropod Nassarius siquijorensis for a period of up to 7 weeks. We then investigated the influences of prey type, metal burden, and subcellular distribution in the prey on the metal accumulation, trophic transfer, and potential toxicity on N. siquijorensis. We demonstrated an obvious negative relationship between the trophic transfer and the metal concentration in prey or the metal dosage. N. siquijorensis exhibited food avoidance behavior to the Cu contaminated food, which effectively reduced the metal ingestion and resulted in a decrease of trophic transfer, as well as a potential toxic effect from dietary exposure. On the other hand, our results also implied the metal-specific impact of subcellular metal distribution in prey on the trophic transfer to N. siquijorensis. Our study suggested that metal burden and feeding avoidance should be considered in studying the trophic transfer of metals in marine benthic food chain.

Copper effects on key metabolic enzymes and mitochondrial membrane potential in gills of the estuarine crab Neohelice granulata at different salinities

The estuarine crab Neohelice granulata was exposed (96 h) to a sublethal copper concentration under two different physiological conditions (hyperosmoregulating crabs: 2 ppt salinity, 1 mg Cu/L; isosmotic crabs: 30 ppt salinity, 5 mg Cu/L). After exposure, gills (anterior and posterior) were dissected and activities of enzymes involved in glycolysis (hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase), Krebs cycle (citrate synthase), and mitochondrial electron transport chain (cytochrome c oxidase) were analyzed. Membrane potential of mitochondria isolated from anterior and posterior gill cells was also evaluated. In anterior gills of crabs acclimated to 2 ppt salinity, copper exposure inhibited hexokinase, phosphofructokinase, pyruvate kinase, and citrate synthase activity, increased lactate dehydrogenase activity, and reduced the mitochondrial membrane potential. In posterior gills, copper inhibited hexokinase and pyruvate kinase activity, and increased citrate synthase activity. In anterior gills of crabs acclimated to 30 ppt salinity, copper exposure inhibited phosphofructokinase and citrate synthase activity, and increased hexokinase activity. In posterior gills, copper inhibited phosphofructokinase and pyruvate kinase activity, and increased hexokinase and lactate dehydrogenase activity. Copper did not affect cytochrome c oxidase activity in either anterior or posterior gills of crabs acclimated to 2 and 30 ppt salinity. These findings indicate that exposure to a sublethal copper concentration affects the activity of enzymes involved in glycolysis and Krebs cycle, especially in anterior (respiratory) gills of hyperosmoregulating crabs. Changes observed indicate a switch from aerobic to anaerobic metabolism, characterizing a situation of functional hypoxia. In this case, reduced mitochondrial membrane potential would suggest a decrease in ATP production. Although gills of isosmotic crabs were also affected by copper exposure, changes observed suggest no impact in the overall tissue ATP production. Also, findings suggest that copper exposure would stimulate the pentose phosphate pathway to support the antioxidant system requirements. Although N. granulata is very tolerant to copper, acute exposure to this metal can disrupt the energy balance by affecting biochemical systems involved in carbohydrate metabolism.

Toxicity tests aiming to protect Brazilian aquatic systems: current status and implications for management

The current status of toxicological tests performed with Brazilian native species was evaluated through a survey of the scientific data available in the literature. The information gathered was processed and an electronic toxicology database (http://www.inct-ta.furg.br/bd_toxicologico.php) was generated. This database provides valuable information for researchers to select sensitive and tolerant aquatic species to a large variety of aquatic pollutants. Furthermore, the toxicology database allows researchers to select species representative of an ecosystem of interest. Analysis of the toxicology database showed that ecotoxicological assays have significantly improved in Brazil over the last decade, in spite of the still relatively low number of tests performed and the restricted number of native species tested. This is because most of the research is developed in a few laboratories concentrated in certain regions of Brazil, especially in Southern and Southeast regions. Considering the extremely rich biodiversity and the large variety of aquatic ecosystems in Brazil, this finding points to the urgent need for the development of ecotoxicological studies with other groups of aquatic animals, such as insects, foraminifera, cnidarians, worms, amphibians, among others. This would help to derive more realistic water quality criteria (WQC) values, which would better protect the different aquatic ecosystems in Brazil. Finally, the toxicology database generated presents solid and science based information, which can encourage and drive the Environmental Regulatory Agencies in Brazil to derive WQC based on native species. In this context, the present paper discusses the historical evolution of ecotoxicological studies in Brazil, and how they have contributed to the improvement of the Brazilian Federal and Regional regulations for environment.

Effects of copper, zinc and dragonfly kairomone on growth rate and induced morphology of Bufo arabicus tadpoles

It is well documented that many amphibian species can detect chemical signals from predatory invertebrates and subsequently develop alternate phenotypes that are protective against predation. The effects of metallic pollutants on the development of predator-induced morphology have not previously been reported. Tadpoles of the Arabian toad Bufo arabicus were exposed for 20 days to copper (0, 10 or 100 μg/L), zinc (0, 10 or 100 μg/L) and kairomones of larval dragonflies (Crocothemis erythrea 1 dragonfly/12 L) in a fully crossed design. The effects of these treatments of growth and body shape were measured. Measured copper concentrations after 24 h were 4.25 μg/L±1.30 (10 μg/L nominal) and 34.9 μg/L±2.15 (100 μg/L nominal). Measured zinc concentrations were 3.04 μg/L±0.1 (10 μg/L nominal) and 26.3 μg/L±12.3 (100 μg/L nominal). Tadpoles exposed to 34.9 μg/L copper were significantly lighter and had a shorter body length than other groups. There was no direct effect of zinc on growth or tadpole shape. Tadpoles exposed to dragonfly kairomones were heavier, wider and had deeper bodies when viewed laterally and had longer tails but overall length was not affected. At 4.25 μg/L copper differences between the control and predator-exposed phenotypes increased but at 34.9 μg/L the phenotypes converged, indicating that copper may inhibit the induced response.

Macrobenthic community response to copper in Shelter Island Yacht Basin, San Diego Bay, California

We examined Cu contamination effects on macrobenthic communities and Cu concentration in invertebrates within Shelter Island Yacht Basin, San Diego Bay, California. Results indicate that at some sites, Cu in sediment has exceeded a threshold for "self defense" mechanisms and highlight the potential negative impacts on benthic faunal communities where Cu accumulates and persists in sediments. At sites with elevated Cu levels in sediment, macrobenthic communities were not only less diverse but also their total biomass and body size (individual biomass) were reduced compared to sites with lower Cu. Cu concentration in tissue varied between species and within the same species, reflecting differing abilities to "regulate" their body load. The spatial complexity of Cu effects in a small marina such as SIYB emphasizes that sediment-quality criteria based solely on laboratory experiments should be used with caution, as they do not necessarily reflect the condition at the community and ecosystem levels.

Reproductive and life stage-specific effects of aqueous copper on the grass shrimp, Palaemonetes pugio

Palaemonetes pugio exposed to copper (9 or 26 microg Cu(2+)/L) for a full life cycle were unable to produce viable embryos, precluding completion of the life cycle, despite no lethal effects on larval, juvenile, or adult life stages. Exposure to copper also resulted in a significant delay in larval development. When adults raised in copper were transferred to control seawater, they produced viable embryos, but larval output per clutch was reduced by 43% compared to clutches from females that had never been exposed to copper, suggesting reduced energetic allocation to reproduction. In acute exposures, adults exposed to copper for as little as three days were unable to produce viable embryos. Furthermore, exposure of control embryos to copper reduced hatching success by 74%. The reduction in hatching success and energetic allocation to reproduction are unlikely to be completely responsible for the lack of larval production observed in pre-spawning exposures to copper, suggesting that copper may also inhibit processes before or during spawning and fertilization.

Effects of zinc on molting and body weight of the estuarine crab Neohelice granulata (Brachyura: Varunidae)

The semiterrestrial burrowing crab Neohelice granulata is one of the main inhabitants of the supratidal and intertidal zones of brackish salt marshes, estuaries and coastal lagoons from South America's Atlantic littoral. A large population of this species spreads out Mar Chiquita coastal lagoon (in Argentina) and its corresponding wetlands, and is considered as a key species within this system. Since high values of dissolved heavy metals (including Zn) have been recently reported within Mar Chiquita coastal lagoon, with levels unusually higher than those from other coastal systems within Argentina, it has been explored that the existence of a risk of environmental conditions endanger these populations. So, juveniles of this estuarine crab were experimentally exposed to increasing concentrations of dissolved Zn (i.e., 0, 0.5 and 1 mg Zn(2+)L(-1)) during six months, the time involved between two successive molts; in addition, both the size and weight reached after each molt were also studied in this assay. It can be concluded that zinc can be toxic to crabs only at high concentrations. Considering that levels up to 1 mg ZnL(-1) were recently reported in Mar Chiquita coastal lagoon waters, the potential occurrence of mean chronic effects on the crab population within the coastal lagoon is discussed.

Long-term ammonia toxicity to the pink-shrimp Farfantepenaeus paulensis

Juvenile pink-shrimp Farfantepenaeus paulensis were exposed (75 days) to NH(3) (0.016-0.287 mg L(-1)) under static condition with water renewal every 24h. Experiments were performed at 20 degrees C, at a water salinity of 15 ppt, and at pH 7.8. Endpoints analyzed were survival, growth and predation rates. After 75 days of exposure, survival was >or=90% in all concentrations tested. However, growth (carapace length and wet body mass) was reduced after exposure to NH(3) concentrations as low as 0.033 mg L(-1), while the relative growth (dry body mass and ash content) was reduced after exposure to the highest NH(3) concentration (0.287 mg L(-1)). Predatory activity was inhibited after exposure to 0.144 or 0.287 mg L(-1) NH(3). Post-larvae exposed (75 days) to 0.301 mg L(-1) NH(3) under the same experimental conditions also showed a reduced growth (wet body mass) and relative growth (dry body mass). In addition, they showed decreased body lipids content and increased body glycogen and glucose contents. However, no changes in body protein, chitin and uric acid contents were observed. Also, NH(3) did not affect post-larvae feeding response. Altogether, findings suggest that F. paulensis reduces its food intake to limit the internal accumulation of nitrogenous waste products when exposed for long time to high levels of ambient ammonia. As a consequence, shrimp show a marked change in energy metabolism, characterized by a decreased content of body lipids paralleled by an increased content of body carbohydrates, resulting in a significant reduction in growth.

Bioenergetic effects of aqueous copper and cadmium on the grass shrimp, Palaemonetes pugio

Adult grass shrimp (Palaemonetes pugio) were exposed to either aqueous copper (ranging from 7.54 to 41.29 microg Cu(2+)/L) or cadmium (2.48- 6.55 microg Cd(2+)/L) for 14 days in laboratory experiments to quantify effects on survival and bioenergetic processes, including respiration, somatic growth, energy (lipid) storage, and food consumption. The lowest observed effect concentrations for mortality were 41.29 microg Cu(2+)/L or 6.55 microg Cd(2+)/L, expressed as free metal ion concentrations. Both copper and cadmium caused a decrease in respiration rate at concentrations of 7.54 to 41.29 microg Cu(2+)/L or 6.55 microg Cd(2+)/L. Exposure to copper (>or=27.03 microg Cu(2+)/L) resulted in negative somatic growth (i.e., weight loss). Cadmium exposure (6.17 microg Cd(2+)/L) caused a decrease in growth rate, relative to the control, but growth remained positive. Nonpolar lipid content and food consumption were not significantly affected by exposure to either copper or cadmium. Our results suggest that both copper and cadmium result in overall metabolic depression, decreasing energy allocation to both maintenance and production.

Relating disparity in competitive foraging behavior between two populations of fiddler crabs to the subcellular partitioning of metals

Behavioral changes in aquatic organisms such as reduced prey capture and decreased mobility have been linked to exposure to contaminants in the field. The purpose of this study was to compare competitive foraging and dominance behaviors of two populations of the fiddler crab, Uca pugnax, and to examine the relationship between tissue metal residues and observed differences in behavior. Foraging behavior (number of total scoops and scoops on a protein-rich patch) and dominance behavior (percentage of successful attacks) of fiddler crabs from an impacted site (Meredith Creek, New York) and a reference site (Tuckerton, New Jersey) were compared in the laboratory. Tuckerton (Tk) crabs were found to have twice the number of total scoops (70 vs. 38 scoops, p < 0.05) and three times the number of scoops on patch (34 vs. 10 scoops, p < 0.05) than Meredith (Me) crabs. No difference was observed between crab populations in the number of successful attacks (i.e., fights over the protein-rich patch). Analyses of total metal body burdens and metals associated with various subcellular fractions showed that, when compared with Tk crabs, Me crabs had higher levels of Ag, Cd, Cu, Ni, and Se in the heat-denatured proteins (HdeP) (i.e., enzymes). Metal bioaccumulation can have inhibitory effects on enzymes, which play an essential role in the regulation of various biochemical, metabolic, and physiological activities in crustaceans. This study suggests that there is a relationship between the accumulation of metals in HdeP (i.e., enzymes) and impairment of competitive foraging behavior in fiddler crabs. Additionally, this study shows that when compared with dominance behavior, foraging behavior is a more sensitive indicator of metal exposure and might be used as an end point in ecotoxicology studies.

Heavy metal toxicity in Exosphaeroma gigas (Crustacea, Isopoda) from the coastal zone of Beagle Channel

Acute toxicity of copper, cadmium, and zinc on isopod Exosphaeroma gigas was evaluated at 20 per thousand and 30 per thousand salinity. Six concentrations were assayed to estimate effective concentration of the toxicant that affects 50% of tested animal (EC50), while physiological responses and bioaccumulation were determined at 0.42 and 1.95 mg L(-1) of each metal. The following toxicity orders were obtained: Cd>or=Cu>Zn at 20 per thousand salinity and Cu>Zn>or=Cd at 30 per thousand salinity. Copper treatments showed a reduction in oxygen consumption at 30 per thousand salinity, while an opposite trend was observed at 20 per thousand salinity. Zinc caused dissimilar effects, while in cadmium significant reduction was only registered in 0.42(20 per thousand) mg L(-1). Ammonia excretion was generally higher in treatments than control at 20 per thousand salinity. At 30 per thousand salinity, excretion did not change in relation to control or diminished. In general terms, O:N atomic ratios indicated a preponderant protein metabolism. Bioaccumulation of assayed metals was higher at lowest salinity and increased with increasing toxic concentrations.

Physiological effects of copper in the euryhaline copepod Acartia tonsa: waterborne versus waterborne plus dietborne exposure

The physiological effects of waterborne and waterborne plus dietborne copper exposure were determined in the euryhaline copepod Acartia tonsa at different salinities (5, 15 and 30ppt). Copepods were exposed (48h) to a reported 48-h LC50 for copper (CuCl(2)), which had been previously determined under the same experimental conditions. Whole body copper accumulation, ion concentrations (Na(+), Cl(-), Mg(2+)), and Na(+), K(+)-ATPase activity were the endpoints measured in all experimental groups. Feeding rate was also measured in fed experimental groups. In copper-exposed copepods, whole body copper accumulation was dependent on salinity, decreasing as salinity increased. However, it was similar in copepods exposed to waterborne and waterborne plus dietborne copper, irrespective the salinity tested. Waterborne copper exposure induced a disturbance of the whole body Na(+) concentration in all salinities tested. This effect was characterized by an increased whole body Na(+) concentration in seawater (salinity 30ppt) and a decreased whole body Na(+) concentration at lower salinities (5 and 15ppt). The ionoregulatory imbalance in low salinity (5ppt) was associated with an inhibition of the whole body Na(+), K(+)-ATPase activity, as observed in freshwater fish and crustaceans. When copepods were exposed to waterborne plus dietborne copper, the physiological effects described were only observed at a low salinity (5ppt) and were associated with a marked inhibition of the feeding rate. Taken altogether, the data suggest that the physiological effects induced by waterborne copper exposure in A. tonsa acclimated to higher salinities (15 and 30ppt) are due to a combined effect of food restriction and copper exposure. Differential physiological responses to waterborne and waterborne plus dietborne copper cannot be ascribed to differences in whole body copper burden.

Pollution biomarkers in estuarine animals: critical review and new perspectives

In this review, recent developments in monitoring toxicological responses in estuarine animals are analyzed, considering the biomarker responses to different classes of pollutants. The estuarine environment imposes stressful conditions to the organisms that inhabit it, and this situation can alter their sensitivity to many pollutants. The specificity of some biomarkers like metallothionein tissue concentration is discussed in virtue of its dependence on salinity, which is highly variable in estuaries. Examples of cholinesterase activity measurements are also provided and criteria to select sensitive enzymes to detect pesticides and toxins are discussed. Regarding non-specific biomarkers, toxic responses in terms of antioxidant defenses and/or oxidative damage are also considered in this review, focusing on invertebrate species. In addition, the presence of an antioxidant gradient along the body of the estuarine polychaete Laeonereis acuta (Nereididae) and its relationship to different strategies, which deal with the generation of oxidative stress, is reviewed. Also, unusual antioxidant defenses against environmental pro-oxidants are discussed, including the mucus secreted by L. acuta. Disruption of osmoregulation by pollutants is of paramount importance in several estuarine species. In some cases such as in the estuarine crab Chasmagnathus granulatus, there is a trade off between bioavailability of toxicants (e.g. metals) and their interaction with key enzymes such as Na(+)-K(+)-ATPase and carbonic anhydrase. Thus, the metal effect on osmoregulation is also discussed in the present review. Finally, field case studies with fish species like the croaker Micropogonias furnieri (Scianidae) are used to illustrate the application of DNA damage and immunosuppressive responses as potential biomarkers of complex mixture of pollutants.

Copper reduced mating behaviour in male shore crabs (Carcinus maenas (L.))

Many crustaceans use pheromones to find mates and induce mating behaviours. If pollutants impair the ability to detect chemosensory cues and respond to pheromone signals, they could profoundly affect mating. In a series of laboratory experiments, the effect of copper (0, 0.1 or 0.5 mg Cu(II) per litre for 5 days) on specific components of the mating behaviour of male shore crab Carcinus maenas was investigated, as well as differences in sensitivity between red and green colour morphs. The results show that copper exposure clearly altered the response of C. maenas males to a pheromone stimulus (pre-moult female urine) presented alone, together with a dummy female (a sponge injected with pre-moult female urine) or with a real female. Crabs exposed to the highest copper treatment took more than twice as long to initiate search activity after pheromone introduction and their search behaviour was less directed. When offered a dummy female, male crabs showed decreased pheromone discrimination in both copper treatments. Stroking was the only mating behaviour significantly affected, with a 90% reduction in red crabs in the highest copper treatment. Additionally, crabs of the highest copper treatment more often pinched the dummy female (non-mating behaviour). Finally, male crabs exposed to copper more often pinched pre-moult females and it took about three times longer to establish cradle-carrying. Thus, copper affects the ability of males to detect female pheromones, perform specific mating behaviours and to form pairs.

Effects of manganese on chemically induced food search behaviour of the Norway lobster, Nephrops norvegicus (L.)

The decapod Norway lobster, Nephrops norvegicus (L.), lives on muddy sediments rich in manganese (Mn). In hypoxic conditions, manganese is reduced and released from the sediment, so increased concentrations of dissolved Mn(2+) become bioavailable. In excess, manganese acts as a neurotoxin and may inhibit vital functions of benthic organisms, such as muscle contraction. We investigated in a laboratory flume experiment, the effect of environmentally realistic concentrations of manganese (0.1 and 0.2mM for 12 days) on the food search behaviour of N. norvegicus. We found that lobsters exposed to manganese had a more than doubled reaction time to food odour stimuli compared to the controls (p<0.05). In addition, manganese exposure reduced the number of N. norvegicus reaching the food stimuli source. Compared to the controls where 86% reached the stimuli source, only about half of the lobsters exposed to 0.1mM Mn and one-third of the lobsters exposed to 0.2mM Mn reached the stimuli source (p<0.05 and 0.001, respectively). There was no significant difference between treatments in the number of lobsters leaving their shelter or in the time from reaction until leaving the shelter and there was no difference in search time for those animals that eventually did locate the stimuli source. This study shows that environmentally realistic manganese concentrations affect parts of the food search behaviour of N. norvegicus, likely due to impaired chemosensory ability or reduced motivation for feeding. Thus, the ability of N. norvegicus to detect and find food can be reduced in areas with high manganese concentrations, with possible consequences on individual and population levels.