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This study investigated the effects of Bisphenol A (BPA), a common endocrine-disrupting chemical, on the antioxidant enzyme activities in the hepatopancreas and the expression of genes related to ovarian development in oriental river prawns (Macrobrachium nipponense). The 24hLC50 and 48hLC50 values for BPA were 80.59 mg/L and 63.90 mg/L, respectively, with a safe concentration of 12.06 mg/L. Prawns were exposed to low (4.85 mg/L), safe (12.06 mg/L), and high (30.00 mg/L) concentrations of BPA for 10 days to measure enzyme activities, and for 20 days followed by 7 days in BPA-free water to measure gene expression. Short-term exposure (12 h, 1d, 3d) to low concentration BPA did not significantly affect superoxide dismutase (SOD) activity in the hepatopancreas (P > 0.05), but long-term exposure (6d, 10d) significantly reduced SOD activity (P < 0.05). Catalase (CAT) activity showed no significant changes throughout the low concentration exposure period (P > 0.05). At safe and high concentrations, SOD and CAT activities significantly decreased after 12 h of exposure (P < 0.05). BPA affected heat shock protein 90 (HSP90) expression in the ovary, with low concentration BPA significantly upregulating HSP90 after 1 day (P < 0.05), but returning to normal levels after 10 and 20 days. At the safe concentration, HSP90 was significantly upregulated at all three sampling points (1d, 10d, 20d) (P < 0.05), while high concentration exposure led to significant upregulation only on day 10 (P < 0.05). Low concentration BPA had no significant effect on Cathepsin B (CB) and Cathepsin L (CL) gene expression in the ovaries (P > 0.05). However, safe concentration exposure promoted CB expression on days 1, 10, and 20 (P < 0.05), while high concentration exposure significantly increased CB expression on day 1 (P < 0.05), with levels returning to normal on days 10 and 20. CL expression significantly increased after 20 days of exposure to both safe and high concentrations (P < 0.05). Gene expression levels in the ovaries returned to normal after transfer to BPA-free water, with HSP90 and CB normalizing by day 1, and CL by day 7. These results indicate that even safe concentrations of BPA impose stress on the hepatopancreas and increase the expression of HSP90, CB, and CL genes in the ovaries, affecting ovarian development. And, these effects are reversible within a certain period after the removal of BPA., Competing Interests: Declaration of competing interest The authors declare that there are no known competing financial interests or personal relationships that could have appeared to influence the work reported in this study., (Copyright © 2024. Published by Elsevier B.V.)

Habitat selection by aquatic organisms is dependent on the availability of adequate conditions to support life and the benefits that the habitat provides. Contaminated environments tend to be less attractive to organisms because reduced habitat quality leads to increased maintenance costs. Consequently, reduced colonization of such disturbed habitats is an expected response. However, colonization has been understudied as an ecotoxicological test endpoint, despite its proven ability to assess habitat selection by populations across various taxa. The aim of the present study was to investigate whether previous exposure to copper could alter the colonization behavior of the freshwater prawn Macrobrachium rosenbergii along a non-forced exposure gradient of interconnected copper-contaminated habitats (0 to 500 µg/L) due to physiological and behavioral impairments. To assess this, post-larvae of M. rosenbergii were pre-exposed to 0, 50, 250 and 500 µg/L copper for a maximum period of 48 h. The physiological status and motility of the organisms after pre-exposure to copper were evaluated using behavioral endpoints (swimming activity by video tracking) and biochemical biomarkers (biotransformation, oxidative stress and neurotoxicity). The results indicated that pre-exposure to copper (at concentrations of 0, 50 and 500 µg/L) significantly influenced the median colonization concentration (CC50), which decreased from 270 µg/L to 109 µg/L. None of the assessed swimming parameters (speed, motility rate, exploration rate, and total distance) were affected by the pre-exposure to copper (0, 50 and 250 µg/L). Biochemically, cholinesterase levels were only affected in the prawn population exposed to 250 µg/L of copper. The present study provides a better understanding of the relevance of colonization as an ecotoxicological endpoint for assessing the spatial distribution of populations, including both new inhabitants and previously exposed organisms, in recovering habitats., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Aquatic environmental pollutants have various impacts on aquaculture. Specifically, sulfide has been established as being toxic to aquatic animals including the oriental river prawn Macrobrachium nipponense. In response, the hepatopancreas has been broadly studied, as it plays a pivotal role in arthropod nutrient digestion and absorption, energy supply, and organ development as well as in crustacean immunity. However, the underlying molecular mechanisms of hepatopancreas's response to sulfide toxicity are still poorly understand. Herein, we used Nova-seq 6000 platform to conduct a comparative transcriptome analysis of gene expression profiles in the hepatopancreas of M. nipponense, while it was under the influence of a semi-lethal sulfide concentration (3.20 mg/L at 48 h). A total of 139 million raw reads were obtained, in which 67,602 transcripts were clustered into 37,041 unigenes for further analysis. After constant sulfide exposure for 48 h, 235 differentially expressed genes, i.e., DEGs (151 up-regulated and 84 down-regulated) were identified in the sulfide treatment group (TGHP) compared with the control group (CGHP). We used GO and KEGG databases to annotate all the DEGs into 1180 functions and 123 pathways, respectively. The metabolic pathways included proximal tubule bicarbonate reclamation, sulfur metabolism, glycolysis and gluconeogenesis, and the TCA cycle; while immune-related pathways contained Ras, Rap1, focal adhesion and platelet activation. Additionally, apoptosis-involved pathways e.g., lysosome, also exhibited remarkable alteration in the presence of sulfide stress. Notably, responses to external stimuli and detoxification genes- such as GSKIP, CRT2, APOD, TRET1, CYP4C3 and HR39- were significantly altered by the sulfide stress, indicating that significant toxicity was transferred through energy metabolism, growth, osmoregulatory processes and immunity. Finally, we demonstrated that in the present of sulfide stress, M. nipponense altered the expression of detoxification- and extracellular stimulation-related genes, and displayed positive resistance via tight junction activation and lysosome pathways. The results of these novel experiments shed light on the hepatopancreas's molecular response to sulfide stress resistance and the corresponding adaptation mechanism; and enable us to identify several potential biomarkers for further studies., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Many early stages of estuarine species congregate at the surface or in the upper mixing layer making them prone to UV light exposure and oil sheens. Laboratory testing was used to assess UV-oil sheen interactions with grass shrimp (Palaemon pugio). Newly hatched grass shrimp larvae were exposed to a 1-μm thick oil sheen for 24 h with or without an 8-h pulse of UV light. Grass shrimp were then transferred to clean seawater and non-UV conditions to measure development, growth, and reproductive fitness. Minimal toxicity was observed after the initial exposure but larval development was significantly delayed in shrimp exposed to the UV enhanced sheen. After reaching sexual maturity, shrimp were paired to evaluate effects on reproduction. Shrimp initially exposed to the UV enhanced sheen as larvae had a significant reduction in fecundity compared to controls. This demonstrates the importance of examining interactions between UV light and oil since negative effects to aquatic organisms may be underestimated if based on standard laboratory fluorescent lighting. Acute exposures of early life stages to thin oil sheens and UV light may lead to long-term impacts to individuals and ultimately to grass shrimp populations., (Published by Elsevier B.V.)

Glyphosate-based herbicides (GBH), including Roundup, are the most widely used pesticides in the world. Glyphosate residues have been detected in surface and groundwater, in food, and in human blood and urine. The effects of this herbicide on different levels of biological organization are an important concern that needs to be investigated. In general, the toxicity of GBH in invertebrates is poorly understood, and it is the motivation of this study. Thus, the aim of this study was to evaluate cellular responses of the hepatopancreas, an organ involved in the detoxification process in invertebrates, after exposure to environmentally relevant concentrations of GBH, using prawn Macrobrachium potiuna as a model. Prawns were exposed to three concentrations of GBH (0.0065, 0.065 and 0.28 mg L -1 ) for 7 or 14 days. Alterations in the morphology of the hepatopancreas and in subcellular components of R cells, which are responsible for the detoxification process, were analyzed, and an index for subcellular alterations was standardized. GBH exposure induced tissue commitments on the hepatopancreas, as well as important impairments of R cells that could compromise the normal functioning of the cells, especially in the detoxification processes. The major cellular impairments were intense vacuolization, dilatation of the cisterns of the rough endoplasmic reticulum and Golgi bodies, increase of perinuclear space, necrosis, concentric membrane formation and mitochondria crest loss. Our data contribute to the knowledge of the cytotoxic effects of low GBH concentrations on aquatic invertebrates, specifically their effects on the hepatopancreas, an important organ for the metabolism of crustaceans. These results also indicate that concentrations considered safe by regulatory agencies should be reviewed to minimize the effects on non-target organisms. This study also contributes to the standardization of an ultrastructure index for the assessment of GBH in palaemonids, which could be used for the assessment of contaminants in crustaceans and other species with hepatopancreas., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Aquaculture has shown great growth in the last decades. Due to the restrictions on water use, production systems are becoming increasingly more intensive, raising concerns about the production water quality. Macrobrachium amazonicum is among the freshwater prawn species with favorable characteristics for production and possibility of intensification. Nitrogen compounds such as ammonia and nitrite affect the health of aquatic organisms since they quickly reach toxic concentrations. These compounds can also cause damage to the gill structure, leading to hypoxia in tissues, affecting acid-base balance, osmoregulation (salt absorption) and ammonia excretion, decreasing the immune capacity of the animal and, in extreme cases, cause death. The aim of this study was to assess histological changes in the gills of Macrobrachium amazonicum juveniles subjected to different concentrations of total ammonia and nitrite. The prawns were subjected to different concentrations of those compounds and their gills were removed and preserved for histological analysis. The gills were assessed for changes according to the Organ Index (I org ) and, for each change, an importance factor (w) was attributed according to the degree of reversibility and applied according to the degree of extension or frequency of the damage. The damage to the gills in the treatments with 100% mortality, both for ammonia and nitrite, corresponded to the high occurrence of progressive, regressive, circulatory, and inflammation damages. The other treatments (which caused less mortality) had mainly inflammation and regressive damages, whose occurrence increased according to the increase in ammonia and nitrite concentration. The histological analysis confirmed that the higher the total ammonia and nitrite concentrations, the larger the damages caused to the gill structure and that lower nitrite concentrations caused similar damages to those caused by higher total ammonia concentrations, which reflects the lower capacity M. amazonicum has to tolerate nitrite., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The aim of this study was to evaluate the toxic effects of chlorpyrifos (CPF) at environmental concentrations on the shrimp Palaemonetes argentinus, a South American native species. Organisms were exposed to environmentally relevant concentrations of CPF (from 3.5 to 94.5ngCPFL(-1)) at laboratory conditions for 96h. A wide battery of biochemical responses including bioaccumulation, damage and defense biomarkers were measured in cephalothorax and abdomen of shrimp. The concentration of CPF was below the detection limit of the method in both body sectors (8ngCPFg(-1)ww), probably indicating fast biotransformation of the parental compound. Our results showed that CPF exposure inhibits acetylcholinesterase activity from 3.5ngCPFL(-1), a concentration below the suggested Argentinean guidelines for the protection of aquatic biota. Moreover, oxidative stress was evidenced by increased H2O2 content and increased levels of TBARs and carbonyl groups in proteins. The induction of antioxidant enzymes like catalase, glutathione S-transferase and glutathione peroxidase seems not be sufficient to prevent oxidative damages. In addition, the mobilization of α-tocopherol from abdomen to cephalothorax was observed and reported for the first time in non-reproductive condition. Likewise, a strong diminution of metallothioneins occurred in cephalothorax from the lowest CPF concentration while induction occurred from the same treatment in abdomen as an oxidative stress response. Finally, significant correlation between Integrated Biomarker Response values and exposure concentrations suggest the usefulness of P. argentinus as bioindicator of CPF exposure at concentrations as low as environmental ones., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Chlordecone (CLD) is an organochlorine insecticide abundant in aquatic environment of the French West Indies. However, few studies have investigated its impact on freshwater invertebrates. Whereas CLD is suspected of inducing endocrine disruption, this work aimed to study the effects of environmentally relevant concentrations of CLD on the 20-hydroxyecdysone (20-HE) hormone concentration and on the chitobiase activity, both having key roles in the molting process of crustaceans. In addition, the bioaccumulation of CLD was measured in the muscle tissue of Macrobrachium rosenbergii to underline potential dose-response relationship. The results have shown that CLD was bioaccumulated in exposed organisms according to a trend to a dose-response relationship. Moreover, it was observed that CLD decreased the 20-HE concentration in exposed prawns when compared to control, whatever the duration of exposure, as well as it inhibited the chitobiase activity after 30days of exposure. The present study indicates that CLD could interfere with molting process of M. rosenbergii by disturbing the 20-HE concentration and the activity of chitobiase, suggesting consequences at the long term on the shrimp development. This study also confirmed that CLD could be an endocrine disruptor in decapod crustaceans, as it was already observed in vertebrates., (Copyright © 2016 Elsevier B.V. All rights reserved.)

We evaluate the effects of total ammonia nitrogen-N (TAN) exposure for 72h on (Na(+),K(+))- and V(H(+))-ATPase activities and on their subunit expressions in gills of the diadromous freshwater shrimp Macrobrachium amazonicum. Specific (Na(+),K(+))- and V(H(+))-ATPase activities increased roughly 1.5- to 2-fold, respectively, after exposure to 2.0mmolL(-1) TAN. Quantitative RT-PCR analyses revealed a 2.5-fold increase in V(H(+))-ATPase B subunit mRNA expression while (Na(+),K(+))-ATPase α-subunit expression was unchanged. Immunohistochemical analyses of the gill lamellae located the (Na(+),K(+))-ATPase throughout the intralamellar septal cells, independently of TAN concentration, while the V(H(+))-ATPase was located in both the apical pillar cell flanges and pillar cell bodies. Systemic stress parameters like total hemocyte count decreased by 30% after exposure to 2.0mmolL(-1) TAN, accompanied by increased activities of the oxidative stress enzymes superoxide dismutase, glutathione reductase and glucose-6-phosphate dehydrogenase in the gills. The stress responses of M. amazonicum to elevated TAN include increases in gill (Na(+),K(+))- and V(H(+))-ATPase activities that are accompanied by changes in oxidative stress enzyme activities, immune system effects and an increase in gill V(H(+))-ATPase gene expression. These findings likely underpin physiological effects in a crustacean like M. amazonicum that exploits multiple ecosystems during its life cycle, as well as under culture conditions that may significantly impact shrimp production by the aquaculture industry., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are recognised as one of the main groups of contaminants that assume more importance in the marine environment, enhancing the need of studies concerning their adverse effects and more efficient and ecologically relevant tools for environmental monitoring purposes. This study aims to apply an integrated approach including several multi-level biological responses (accumulation levels, biochemical responses important for different physiological functions and behavioural alterations) to assess the ecological relevance of the effects induced by sub-lethal concentrations of anthracene (ANT) in Palaemon serratus (common prawn). ANT accumulation was assessed by measuring the levels of ANT-type compounds in prawn digestive gland, muscle and eye; biochemical responses were determined using biomarkers involved in biotransformation, oxidative damage, energy production and neurotransmission processes; and behavioural alterations through swimming performance after 96 h exposure bioassay (ANT:16-1,024 μg/L). The rationale behind this approach is to assess the ecologically relevant effects induced by ANT in prawn, given by the association between behavioural alterations with biochemical responses, in search for more efficient tools for environmental risk assessment. Results show a significant decrease of swimming velocity (LOEC=128 μg/L) along with increased levels of ANT-type compounds in digestive gland (LOEC=128 μg/L), muscle (LOEC=256 μg/L) and eye (LOEC=32 μg/L) in prawn exposed to ANT. Increased activities of glutathione peroxidase (GPx) and catalase (CAT), involved in anti-oxidant defence system, were also observed (LOEC=256 μg/L; 1024μg/L, respectively) in the digestive gland of prawn, induction of oxidative damage in lipids (LPO) also occurred (LOEC=32 μg/L). The inhibition of swimming velocity showed a correlation with some biochemical parameters measured, including the levels of ANT-type compounds in tissues and LPO, and thus these may be considered sensitive and ecologically relevant criteria as well as early warning endpoints for assessing polycyclic aromatic compounds exposure effects on marine organisms., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Trichlorfon is an organophosphorus (OP) insecticide that is used as an agriculture pesticide to destroy insects, a human medicine to combat internal parasites, and an ectoparasiticide in the livestock and aquaculture industries, but which has caused aquatic toxicity in the prawn industry. The aim of this study was to investigate the effects of trichlorfon on molecular and enzymatic processes of the immunological response of the giant freshwater prawn, Macrobrachium rosenbergii, at 0, 0.2, and 0.4mgL(-1) with 0, 3, 6, 12, and 24h of exposure. The total hemocyte count (THC), respiratory bursts (RBs), phenoloxidase (PO) activity, and superoxide dismutase (SOD) activity were examined to evaluate immunological responses and oxidative stress. Results showed that THCs of the prawn exposed to trichlorfon at both concentrations (0.2 and 0.4mgL(-1)) had increased after 12 and 24h; SOD and PO activities had significantly increased at 3h, whereas production of RBs had dramatically increased as oxidative stress at each sampling time after exposure to trichlorfon compared to the control. A potential biomarker of OPs, acetylcholinesterase (AChE) revealed a significant decrease after exposure for 6h, and showed a time-dependent tendency. Immune gene expressions, including prophenoloxidase (proPO), the lipopolysaccharide- and β-1,3-glucan-binding protein (LGBP), peroxinectin (PE), α2-macroglubulin (α2M), transglutaminase (TG), and copper, zinc (Cu,Zn)-SOD, of prawns exposed to trichlorfon at 0, 0.2, and 0.4mgL(-1) for 0, 6, and 24h were further evaluated. Expressions of all of the immune genes significantly decreased when prawns were exposed to 0.4mgL(-1) trichlorfon for 24h, and among them, an increase in SOD expression was seen after exposure to 0.4mgL(-1) for 6h. Prawns exposed to trichlorfon within 24h exhibited the decrease of circulating hemocytes, and also the induction of oxidative stress, which caused subsequent damage to DNA formation of immune genes. From these results, we concluded that immunological responses and immune gene expressions of prawn exposed to trichlorfon at 0.4mgL(-1) for 24h were perturbed, thus causing a deficiency in immunity and subsequent increased susceptibility to pathogen infections., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The main purpose of the present study was to investigate the effects of deltamethrin on biomarkers and behavior of Palaemon serratus (common prawn), since this attempt to link different levels of biological organization will allow determining which biomarkers might be ecologically relevant and will be useful to complement the information about the effects of pesticides by using behavioral parameters. Therefore, parameters of liver antioxidant status, energy metabolism and neurotransmission were determined in different tissues of the common prawn and used to assess the effects at sub-individual level, whereas swimming velocity was used to assess the effects at the individual level. It was also investigated if the swimming velocity can be used as an endpoint in ecotoxicology bioassays and if it can be as sensitive as biomarker endpoints. Swimming velocity was significantly reduced in prawns exposed to deltamethrin, showing a lowest observed effect (LOEC) of 0.6 ng L(-1). Eye acetylcholinesterase (AChE) activity was significantly increased in prawns exposed to 0.6, 1.2 and 2.4 ng L(-1) deltamethrin, whereas muscle cholinesterase (ChE) activity was significantly increased in prawns exposed to 19 and 39 ng L(-1). On the other hand, lactate dehydrogenase (LDH) activity was significantly increased in muscle of prawns exposed to 0.6, 1.2, 2.4, 4.9 ng L(-1) deltamethrin, showing that organisms were requiring additional energy, but probably using it for detoxification processes rather than locomotion, since swimming velocity was inhibited. Glutathione S-transferase (GST) activity was significantly increased in the digestive gland of common prawn exposed to 19 and 39 ng L(-1) deltamethrin. Catalase (CAT) activity was significantly increased in digestive gland of prawn exposed to 19 ng L(-1) deltamethrin. However, CAT activity decreased in digestive gland of prawn exposed to 39 ng L(-1), suggesting an antioxidant defense system failure concomitant with high levels of lipid peroxidation. Thus, global results showed that decreased swimming velocity was not associated with cholinesterase inhibition. In fact, the impairment of swimming velocity may be due to allocation of energy for detoxification and antioxidant protection instead of swimming activity. The present study showed that swimming velocity could be used as an ecologically relevant tool and a sensitive endpoint to assess and complement the study of pesticide effects on marine organisms., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Ingested pollutants may elicit digestive toxicity following incorporation into consumer tissues. This post-assimilatory toxicity may include tissue damage influencing synthesis of digestive enzymes, gut transit time and absorption of nutrients as well as pollutants by the gut epithelium. This study investigated impacts of chronic field exposure on gut residence time (GRT), feces elimination rate (FER), extracellular digestive protease activities and gut pH in grass shrimp Palaemonetes pugio. Adult shrimp were collected from differentially impacted sites within the New York/New Jersey Harbor Estuary and fed prepared meals containing fluorescent or near-infrared markers and analyzed for digestive toxicity. Relationships between digestive parameters and assimilation efficiencies (AE) for Cd, Hg and organic carbon reported previously were also analyzed. Minimum GRT did not vary significantly for field-collected shrimp, but was positively correlated with Cd, but not Hg or carbon, AE. FER was not impacted by field exposure. Digestive protease activities exhibited a marked decrease in grass shrimp from impacted field sites relative to reference shrimp. Relationships between the assimilation of elements and digestive physiology in field-collected shrimp suggest that digestive plasticity (increasing GRT) may be important in compensating for post-assimilatory digestive toxicity (reduced protease activities) in order to maintain nutrient assimilation. Stress-induced variability in digestive function among grass shrimp populations may, in turn, enhance the assimilation of non-essential elements, such as Cd., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A previous in vitro study has indicated that two alkylphenol ethoxylates (APEs) could potentially damage hemocytes and influence cellular immunity of prawns (Macrobrachium rosenbergii). The aim of this study was to investigate the effects of nonylphenol (NP) on susceptibility to a pathogen and on the mRNA expression of hemocyte genes, including four immune-related genes. NP at different concentrations was fed continuously to prawn (M. rosenbergii) for 1, 3, 6, and 9 days. Challenging prawns with Lactobacillus garvieae resulted in 44-50%, 20-24% and 10-12% mortality were detected after prawns were fed with 100, 10 and 1microNP/prawn for 6 days, respectively. In comparison with control prawns fed with phosphate-buffered solution (PBS), the increase of mRNA levels of four immune-related genes, alpha-2 microglobulin (alpha-2m), antimicrobial peptides (amp), peroxinectin (pon), and prophenoloxidase (propo), was detected on days 1, 3 and 6 after feeding with 100microg/prawn; on day 9, only the mRNA level of amp of the NP-treated group was significantly increased, while that of the remaining groups was not different from that of the control. In addition, two other hemocyte genes were also studied, including a respiration-related gene, cytochrome oxidase subunit (cos), and an unknown gene, L12X3. The mRNA level of cos was elevated during the experimental period, but an increase of L12X3 expression was detected only on day 1 after treatment. Regarding sensitivity of these genes to NP, the results from NP-treated prawns on day 1 after treatment revealed (1) that mRNA expression of the six genes in the 100-microg-NP-treated group was significantly different from that of control group, (2) that the mRNA levels of three immune-related genes (amp, pon and propo) in 10-microg-treated group were significantly higher than that of control group, and (3) that a significant change of propo was detected in 1-microg-treated group. These results suggest that NP may enhance the immune response of prawns, but the effect created by a high concentration of NP may damage prawns, and then increase the susceptibility to pathogen.

In an 8-month laboratory experiment, Palaemonetes pugio (grass shrimp) were exposed to aqueous cadmium (free cadmium ion concentrations of 1.51 or 2.51 microg Cd(2+)/L) for an entire life cycle, from larva to reproductive adult and through to production of second-generation larva. Individual-level effects on survival, life stage duration, and reproduction were measured, and population growth was projected using two models: a stage-based matrix model and a z-transformed life cycle graph analysis. Adult survival was significantly reduced at 2.51 microg Cd(2+)/L, but cadmium exposure had no effects on survival or stage duration of embryos, larvae, or juveniles. Survival of second-generation larvae was unaffected by maternal exposure. Brood size was reduced by 27% at 1.51 microg Cd(2+)/L and by 36% at 2.51 microg Cd(2+)/L. The percent of females in the population that was gravid was approximately 50% lower at 2.51 microg Cd(2+)/L, compared to controls. Both population models projected a dose-dependent decrease in population growth rate (lambda), up to a 12% reduction at 2.51 microg Cd(2+)/L, which can be attributed mainly to contributions from reproductive effects. Elasticity analysis revealed that population growth rate was most sensitive to changes in survival of juveniles and adults. However, lethal effects of cadmium made only a small contribution to the effect on population growth rate. Even though both models project positive growth (lambda>1) of grass shrimp populations exposed to low concentrations of cadmium, the ability of populations to withstand predation pressure would be compromised.

Piperonyl butoxide (PBO) is a commonly used synergist in many pyrethroid formulations due to its ability to interfere with cytochrome P450 (CYP) monooxygenases. Because PBO can co-occur in the estuarine environment with polycyclic aromatic hydrocarbons (PAHs), a class of compounds metabolized by CYP isozymes, the overall objective of this study was to investigate the influence of PBO on the bioconcentration and photoinduced toxicity of two common PAH contaminants, fluoranthene (FLU) and benzo[a]pyrene (BaP), on the larvae of the grass shrimp (Palaemonetes pugio). PBO alone was not particularly toxic to grass shrimp larvae. In dark exposures and under simulated sunlight (UV-A=211.0+/-7.0 microW/cm(2), UV-B=9.8+/-2.4microW/cm(2)), 96-h LC(50) values were similar (814.4 and 888.6 microg/L, respectively), suggesting that PBO toxicity is not enhanced in the presence of sunlight. The presence of sublethal concentrations of PBO in single PAH toxicity tests increased the bioconcentration of the two tested PAHs, and these increases were greatest at the lowest tested PAH concentrations. Mean bioconcentration factors (BCF) at the three lowest FLU and BaP treatments increased 14.3- and 7.1-fold, respectively, in the low PBO (127 microg/L) exposure compared to that of the no PBO exposure. Under simulated sunlight, PBO exposure also increased the photoinduced toxicity of the two tested PAHs, and this increase occurred in a PBO concentration-dependent fashion. For FLU, 96-h LC(50) values decreased from 2.35 microg/L in the absence of PBO to 0.76 microg/L in the high PBO (256 microg/L) exposure. For BaP, 96-h LC(50) values similarly decreased from 1.02 microg/L in the absence of PBO to 0.30microg/L in the high PBO exposure. The presence of PBO also influenced the PAH tissue residue-response relationship, but in different ways for FLU and BaP. For FLU, slopes of the tissue residue-response relationship decreased in the presence of PBO, and for BaP, there was a trend towards increased slopes in the presence of PBO. These results demonstrate that sublethal levels of PBO increase the bioconcentration and photoinduced toxicity of certain PAH in grass shrimp larvae, and underscore the need to consider the potential for PBO to synergize the toxicity of co-occurring environmental contaminants in future risk assessments.

The effect of the water-soluble fraction of crude oil (WSF) on lipid metabolism was studied at critical metabolic points, namely fatty acid activation, enzymes of triacylglycerol and phospholipid synthesis, and membrane (lipid packing) properties in the freshwater prawn Macrobrachium borellii. To determine the effect of the contaminant, adults and embryos at different stages of development were exposed to a sublethal concentration of WSF for 7 days. After exposure, microsomal palmitoyl-CoA synthetase (ACS) showed a two-fold increase in adult midgut gland. Embryo's ACS activity was also affected, the increment being correlated with the developing stage. Endoplasmic reticulum acylglycerol synthesis was also increased by WSF exposure in adults and stage 5 embryos, but not at earlier stages of development. Triacylglycerol synthesis was particularly increased (18.5%) in adult midgut gland. The microsomal membrane properties were studied by fluorescent steady-state anisotropy, using the rotational behavior of the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH). Microsomes from midgut gland of WSF-exposed prawn showed no differences in fluidity. Nevertheless, microsomes incubated with WSF in vitro increased their fluidity in a temperature- and WSF concentration-dependent fashion. Both, aliphatic and aromatic hydrocarbons individually tested elicited an increase in membrane fluidity at 10 mg/l, but at 4 mg/l only nC10-C16 aliphatics did. In vivo results indicate that WSF increased the activity of microsomal enzymes that are critical in lipid metabolism, though this change was not due to direct alterations in membrane fluidity, suggesting a synthesis induction, or an enzyme-regulatory mechanism. Nevertheless, hydrocarbons elicited membrane fluidity alterations in in vitro experiments at concentrations that could be found in the environment after an oil spill.

The main purpose of this study was to describe the kinetic properties of the cholinesterase (ChE) enzyme present in the eyes of the prawn Palaemon serratus, an abundant, ecological and commercially relevant species of European coastal environments. The obtained results suggest that the studied enzyme is a ChE and not a non-specific esterase, due to its apparent affinity for choline esters and the high sensitivity to eserine sulphate. This ChE displays a distinct preference for the substrate acetylthiocholine, showing a triphasic behaviour, with activation at low concentrations and inhibition by excess of substrate. Moreover, irreversible ChE inhibition by several organophosphate and carbamate compounds was characterized. All the irreversible inhibitions were homogeneous following a second-order rate reaction. The bimolecular rate constant (k(i)) values of ChE inhibition by the tested pesticides were also estimated and compared with available data from other invertebrate and vertebrate species. In conclusion, the results of the present study showed that prawn eyes possess only one ChE with typical properties of acetylcholinesterase, which is highly sensitive to the tested anti-cholinesterase compounds.

A previous in vitro study has indicated that four phthalate esters (PAEs) could damage hemocytes and decreases the cellular immunity of prawns [Sung, H.H., Kao, W.Y., Su, Y.J., 2003. Effects and toxicity of phthalate esters to hemocytes of giant freshwater prawn, Macrobranchium rosenbergii. Aquat. Toxicol. 64, 25-37]. The aim of this study was to investigate the in vivo effect of four PAEs, diethyl phthalate (DEP), dihexyl phthalate (DHP), dipropyl phthalate (DPrP) and diphenyl phthalate (DPP) on the defense system of the giant freshwater prawn, M. rosenbergii. PAE dissolved in corn oil was continuously fed to prawns for 8 days and five immune parameters (total hemocyte count, THC; ratio of granulocytes to hyalinocytes, G/H; intrahemocytic total phenoloxidase activity, PO(T); intracellular superoxide anion (O2-) production; transglutaminase (TGase) activity) were separately detected on days 1, 4 and 8. In addition, mortality was determined on days 4 and 8 after challenging the prawns with Lactobacillus garvieae. In comparison with untreated prawns, the results showed that DHP demonstrated the lowest toxicity in that it only influenced the PO activity and O2- production before 4 days after treatment and caused 6.6% mortality on day 8. DEP decreased G/H, PO(T) and TGase activity on day 1 and reduced THC, G/H and PO(T) and caused 16.6% mortality on day 4; however, on day 8, it increased O2- production and caused no mortality. In the DPrP-treated group, a reduction of all the immune reactions apart from TGase activity and 22.2% mortality were detected on day 4. As for the effect of DPP, results showed that it decreased all the immune parameters apart from THC on days 1 and 4, but caused no mortality on day 4; but on day 8, an increase of O2- production and 17.7% mortality were detected. These results indicated that the immune reactions of prawns were variable due to the different toxic effects of PAEs. In addition, it was found that, on day 8 after treatment, the three PAEs, DHP, DPrP and DPP increased O2- production and did not influence the other four reactions, but mortality was detected in these groups. These results suggest that other physiological responses may also be affected to increase the susceptibility of prawns to pathogens.

The primary objective of this research was to determine if the genotype of the enzymes glucose phosphate isomerase (Gpi), phosphoglucomutase (Pgm), or mannose phosphate isomerase (Mpi) are factors affecting survival during acute endosulfan, fluoranthene, and chromium(VI) exposures. Palaemonetes pugio were exposed in the laboratory to 6.3 microg/L endosulfan, 100 mg/L chromium(VI), or 0.6 mg/L fluoranthene. Dead shrimp were removed at approximately 15-30 min intervals and the individual's genotypes for the Gpi, Mpi, and Pgm enzymes were determined. These data were used to establish whether allozyme genotype was related to tolerance as analyzed with non-parametric methods (i.e. development of survival curves using the Kaplan-Meier method of estimation) and parametric methods (i.e. proportional hazards models). Since the sex and/or size of the organism was expected to affect tolerance, these variables were accounted for in the proportional hazards models. Results indicated individuals that were heterozygous (MF) for the Gpi allozyme survived longer and had less overall mortality than the homozygous MM genotype when exposed to chromium(VI) and to fluoranthene. No allozyme genotypes were related to tolerance during the endosulfan exposure when sex was included as a covariate in the analysis. These results support the hypothesis that there is a genetic basis for tolerance in P. pugio during acute exposures to chromium(VI) and to fluoranthene. Although a relationship between Gpi genotype and contaminant tolerance has been identified in previous studies, no such relationship has been documented in P. pugio or with chromium(VI) as the contaminant.

Grass shrimp (Palaemonetes pugio) populations exposed to anthropogenic contaminant sources in South Carolina (SC) have reduced densities when compared with populations at SC-reference sites. This laboratory study examined the effects of a commonly used agricultural insecticide, endosulfan, on grass shrimp reproduction. Reproductively active grass shrimp were chronically exposed to sublethal concentrations of endosulfan (200 or 400 ng/l) for 43 days. The cumulative number of females that became gravid and the rate at which they became gravid were measured. Endosulfan exposure reduced the cumulative number of gravid females by 31% in the 200 ng/l exposure and 39% in the 400 ng/l exposure. The first appearance of gravid females in the population was significantly delayed in treated populations compared with the control treatment in a dose dependent manner. Clutch size in these gravid females was not significantly different among the treatments. Additionally, there was no difference in the onset of reproduction in the treated populations. These results implicate a population reduction due to a decrease in the overall number of females becoming gravid in a population over time, not a reduction in clutch size per individual. While the mechanisms of action have yet to be defined, these results indicate that sublethal endosulfan concentrations may have a negative effect on grass shrimp reproductive biology.