Marine Crustacean Species Research Articles

Molecular Identification and Phylogenetic Analysis of Bioluminescent Bacteria Isolated from Selected Marine Crustacean in Manila Bay, Philippines

Bioluminescent bacteria (BLB) are the most widely distributed light-emitting microorganisms, most of which are found as symbionts of free-living marine organisms, including the crustacean species. In this study, 4 out of 7 marine crustaceans in the northeastern section of Manila Bay were found to contain bioluminescent bacteria. Marine crustacean species namely Thenus orientalis (Oriental Slipper Lobster), Oratosquilla oratoria (Mantis Shrimp), Penaeus monodon (Giant Tiger Prawn), Litopenaeus vannamei (Whiteleg shrimp), Scylla serrata (Mud Crab), Portunus pelagicus (Blue Swimming Crab), and Charybdis feriata (Crucifix crab), were swabbed after collection. Bioluminescent bacteria were isolated from the inner surface of the carapace, eyes, abdomen, and abdominal segments of the crustacean samples. All glowing colonies were isolated and upscaled. Only bioluminescent bacteria from T. orientalis, O. oratoria, and P. monodon completed the isolation process and were identified using 16S rRNA gene sequencing for phylogenetic analysis. Furthermore, results from molecular identification through Nucleotide BLAST identified that it was Vibrio alginolyticus and Mucus bacterium. At the same time, the presence of Vibrio rumoiensis was also identified which was proved to be understudied and needs exploration. This study was aimed to identify the present bioluminescent bacteria in selected marine crustaceans in Manila Bay, Philippines through microbiological isolation, molecular identification, and phylogenetic reconstruction.

Marine pollutant Phenanthrene (PHE) exposure causes immunosuppression of hemocytes in crustacean species, Scylla paramamosain

Phenanthrene (PHE), a representative polycyclic aromatic hydrocarbons (PAHs), is widely found in aquatic environments, which exhibits high toxicity to aquatic organisms and has a substantial impact on overall health. In order to investigate the immunosuppressive effects of PHE exposure on marine crustacean species, the Scylla paramamosain was exposure to different concentrations of PHE, which was 0 μg/L (control group), 0.7 μg/L, 7 μg/L, or 70 μg/L PHE with 35 individuals in every group, respectively. The results showed that the color of hemocytes gradually deepened with increasing PHE concentration, and the total hemocyte count (THC) was activated and increased after PHE exposure analyzed by Flow cytometry. Meanwhile, compared with the control group, cryostat sections of hepatopancreas showed cell infiltration, cell steatosis, eosinophilic masses and vacuolization in PHE groups. The superoxide dismutase (SOD) activity was decreased immensely in PHE exposure groups, meanwhile, the acid phosphatase (ACP) activity and glutathione (GSH) activities were increased after PHE exposure compared with control group. Moreover, the expression profile of Crustin, TLR, MCM7, JAK, caspase, Moyosin and P53 were up-regulated significantly after 7th day PHE exposure in all treatment groups by Q-PCR. Those data illustrated that PHE exposure could inhibit the immune function of mud crab by causing hepatopancreas damage, induce the activity of antioxidant enzymes and the expression of immune genes. These data provide a scientific basis for evaluating the impact of PAH pollution on marine organisms.

Complete genome sequence and characterization of four Decapod iridescent virus 1 isolates from crab and shrimp

Decapod iridescent virus 1 (DIV1) is an emerging viral pathogen that infects diverse freshwater and marine crustacean species and causes considerable economic losses that seriously threaten crustacean farming and has caused enormous financial losses in recent years. In this study, we detected DIV1 from diseased crabs, with clinical symptoms such as loss of vitality and white gill filaments with edema, in a Marsupenaeus japonicus and Portunus trituberculatus polyculture pond. Four DIV1 isolates from crab samples (two isolates) and shrimp samples (two isolates) were sequenced and assembled successfully. Molecular characterization and phylogenetic analysis of the four DIV1 isolates were conducted. The DIV1 isolates from crab samples have a close genetic relationship with shrimp DIV1s, indicating the viruses share the same ancestor with those from shrimps. Our study provides valuable insights into disease prevention and control of the shrimp-crab polyculture system.

Molting enhances internal concentrations of fipronil and thereby decreases survival of two estuarine resident marine crustaceans.

In aquatic arthropods, molting is a pivotal physiological process for normal development, but it may also expose them to higher risks from xenobiotics, because the organism may take up additional water during that time. This study aimed to assess the effects of molting on bioconcentration and survival after 96-h exposure to insecticide fipronil with or without oxygenase (CYP450s) inhibitor piperonyl butoxide (PBO) of two estuarine resident marine crustacean species: the sand shrimp Crangon uritai and the kuruma prawn Penaeus japonicus, with 96-h LC50 value of fipronil=2.0µg/L and 0.2µg/L, respectively. Two graded concentrations included group high (H) (equivalent to the 96-h LC50 values) and low (L) (one-tenth of the H group concentration). Molting and survival were individually checked, and internal concentrations of fipronil and its metabolites (fipronil desulfinyl, fipronil sulfide, fipronil sulfone) were measured. The results showed that, only fipronil and fipronil sulfone were detected from organism, and that internal concentrations of these insecticides in molted specimens were higher than those of unmolted ones but comparable with those of dead ones. Accordingly, mortality was more frequent in molted specimens than those that were unmolted. Furthermore, involvement of oxygenase and higher lethal body burden threshold may confer higher tolerance to fipronil in sand shrimp than in the kuruma prawn. This study is the first to demonstrate that the body-residue-based approach is useful for deciphering the causal factors underlying fipronil toxicity, but highlights the need to consider physiological factors in arthropods, which influence and lie beyond body burden, molting and drug metabolism.

The mechanism of semicarbazide (SEM) exposure causes immunosuppression and reduces disease resistance of marine crustacean species, Scylla paramamosain

Semicarbazide (SEM) is a common pollutant in the marine environment. It can cause cell mutation, carcinogenesis, and teratogenesis, threatening the health and survival of marine species. In this study, the immunotoxicity of SEM was investigated in a marine crustacean species, the mud crab Scylla paramamosain. After seven days of exposure to 0.2 μg/L, 2 μg/L, or 20 μg/L concentrations of SEM, the effects of SEM on hemocytes and immune function were analyzed in S. paramamosain. The results showed that the hemolymph color deepened and total hemocyte count (THC) was down-regulated significantly with increasing SEM concentration. Meanwhile, tissue sections showed cell infiltration, cytoplasmic vacuolization, and cell steatosis. The survival rate of hemocytes decreased after SEM treatment in vitro, which revealed that SEM showed a cytotoxic to hemocytes. Superoxide dismutase (SOD), glutathione (GSH), phenoloxidase (PO) and catalase (CAT) activity decreased with increasing SEM concentration, while the activity of glutathione peroxidase (GSH-Px) was increased compared with the control group. Similarly, intracellular ROS content increased to about 1.2-, 1.3-, and 2-fold that of the PBS group after exposure to 0.2, 2, and 20 μg/L SEM, respectively. There was a trend of significant up-regulation of p53 and caspase-3 with increasing concentrations of SEM identified by Q-PCR. Meanwhile, the hemocytes apoptosis rate were increased with the SEM concentration, which induced by caspase-3 pathway activated by SEM. The phagocytic activity of hemocytes decreased with increasing SEM concentration. The challenge experiment illustrated that SEM exposure reduced the resistance of mud crab to Vibrio alginolyticus. Our results demonstrated that SEM exposure could inhibit the immune function by causing cell damage, inducing reactive oxygen species (ROS), reducing the activity of antioxidant enzymes and inducing hemocytes apoptosis in a marine crustacean species. SynopsisSEM in seawater could inhibit the immune function and threaten the survival in crustaceans.

A chromosome-level genome of the kuruma shrimp (Marsupenaeus japonicus) provides insights into its evolution and cold-resistance mechanism

Marsupenaeus japonicus is an important marine crustacean species. However, a lack of genomic resources hinders the use of whole genome sequencing to explore their genetic basis and molecular mechanisms for genome-assisted breeding. Consequently, we determined the chromosome-level genome of M. japonicus. Here we determine the chromosome-level genome assembly for M. japonicus with a total of 665.19 Gb genomic sequencing data, yielding an approximately1.54 Gb assembly with a contig N50 size of 229.97 kb and a scaffold N50 size of 38.27 Mb. With the high-throughput chromosome conformation capture (Hi-C) technology, we anchored 18,019 contigs onto 42 pseudo-chromosomes, accounting for 99.40% of the total genome assembly. Analysis of the present M. japonicus genome revealed 24,317 protein-coding genes and a high proportion of repetitive sequences (61.56%). The high-quality genome assembly enabled the identification of genes associated with cold-stress and cold tolerance in kuruma shrimp through the comparison of eyestalk transcriptomes between the low temperature-stressed shrimp (10 °C) and normal temperature shrimp (28 °C). The genome assembly presented here could be useful in future studies to reveal the molecular mechanisms of M. japonicus in response to low temperature stress and the molecular assisted breeding of M. japonicus in low temperature.

What evidence exists for the impact of climate change on the physiology and behaviour of important aquaculture marine crustacean species in Asia? A systematic map protocol

BackgroundClimate is one of the most important driving factors of future changes in terrestrial, coastal, and marine ecosystems. Any changes in these environments can significantly influence physiological and behavioural responses in aquatic animals, such as crustacea. Crustacea play an integral role as subsistence predators, prey, or debris feeders in complex food chains, and are often referred to as good indicators of polluted or stressed conditions. They also frequently have high production, consumption, and commercial significance. However, crustacean’s responses to climate change are likely to vary by species, life-history stage, reproduction status and geographical distribution. This map is undertaken as part of the Long-Term Research Grant project which aims to identify any interactive effect on physiological compensation and behavioural strategy of how marine organisms, especially crustaceans, deal with stress from environmental change. Our proposed map will aim to outline the evidence currently existing for the impacts of climate change on the physiology and behaviour of important aquaculture crustacean species within Asia.MethodsWe will document peer-reviewed articles in English using published journal articles and grey literature. Two bibliographic databases (Scopus and Web of Science) and multiple organizational websites with Google scholars will be searched. The systematic map protocol will follow in accordance with the Collaboration for Environmental Evidence Guidelines and Standards. Literature will be screened at the title, abstract, and full-text level using pre-defined inclusion criteria. The map will highlight marine crustacea physiological compensation and behavioural strategies to cope with climate change. It will also improve our knowledge of the available evidence and current gaps for future research recommendations.

Immunotoxicity of polychlorinated biphenyls (PCBs) to the marine crustacean species, Scylla paramamosain

Polychlorinated biphenyls (PCBs) are persistent organic pollutants in environments, and they can negatively affect aquatic animal health. After 7 days of PCBs exposure, the activities of catalase, phenoloxidase, and superoxide dismutase and the total hemocyte count in the haemolymph were significantly decreased and the reactive oxygen species (ROS) content and phagocytic rate of hemocytes were significantly increased in mud crab Scylla paramamosain. Additionally, serum lysozyme, glutathione, glutathione-S-transferase, and glutathione peroxidase activities were significantly down-regulated in mud crab after PCBs exposure. The survival rate of crab hemocytes significantly declined as the PCBs concentration increased, indicating that PCBs had a cytotoxic effect on hemocytes. Exposure to increasing concentrations of PCBs also increased the degree of DNA damage in crab hemocytes. After PCBs exposure, the expression levels of P53 and caspase-3 in hemocytes were significantly up-regulated, which suggests that apoptosis was occurring. The apoptosis rate of hemocytes was up-regulated as the PCBs concentration increased, indicating that apoptosis was induced by the PCBs-activated caspase-3 pathway. These data suggest that exposure to PCBs hampered the immune response of mud crabs, most likely by (1) inducing ROS, causing DNA damage, and reducing the viability of hemocytes, (2) reducing the activities of antioxidant enzymes, and (3) inducing phagocytosis and apoptosis of hemocytes. And the final result of PCBs-induced immunotoxicity to mud crabs is the reduced bacterial disease resistance and survival rate of crabs under Vibrio alginolyticus challenge.

Antenna regeneration as an ecotoxicological endpoint in a marine amphipod: a proof of concept using dimethyl sulfoxide and diflubenzuron.

Regeneration is a widely spread process across the animal kingdom, including many species of marine crustaceans. It is strongly linked to hormonal cycles and, therefore, a great endpoint candidate for toxicology studies. We selected the amphipod Parhyale hawaiensis as test organism, already used in ecotoxicological studies and able to regenerate its body appendages. We are proposing a protocol to use the antenna regeneration as a toxicity endpoint. First, we evaluated differences in time of completion of regeneration in males and females after the amputation of one antenna of 6 months old animals. Then we compared the influence of different testing volumes in the regeneration process (100 and 5 mL). We used as testing substances, dimethyl sulfoxide (DMSO) and diflubenzuron, a chitin synthesis inhibitor. The most suitable protocol consisted of volumes of 5 mL in 12-well microplates, with 1 organism per well, 12 organisms per concentration (1:1 females/males) and test time duration of around 5 weeks. DMSO accelerated regeneration time with a NOEC of 0.06%. Diflubenzuron inhibited the time necessary to its completion with a NOEC of 0.32 μg L-1. We conclude that the Parhyale hawaiensis antenna regeneration protocol proposed here is a potential tool in ecotoxicology, but more studies are required for its validation not only to verify its utility for testing chemicals but also environmental samples.

Enhanced immune responses and protection against the secondary infection in mud crab (Scylla paramamosain) primed with formalin-killed Vibrio parahemolyticus

Mud crab (Scylla paramamosain) is an economically important marine crustacean species commonly distributed in China and Indo-west Pacific countries. However, the disease outbreaks caused by Vibrio parahemolyticus have resulted in high mortality and disastrous economic losses in the mud crab culture industry. Immune priming has shown the capacity of protecting invertebrates against pathogens in the second exposure, with profound implications for the prevention of infectious diseases. In this study, the survival and immune responses of mud crabs received primary exposure to formalin-killed V. parahemolyticus (immune priming, IP) and secondary challenge with live counterparts (lethal challenge, LC) were investigated. The priming dose of 2 × 105 cells·g−1 of inactivated V. parahemolyticus showed the highest survival rate (75.7%). There was no significant difference among the primed groups that received lethal challenge at different time points (P > .05). The cumulative survival of the primed (FVP) group (73.5%) was significantly higher than that of the control (SA) and naïve groups after the second challenge with live V. parahemolyticus. The efficiency of pathogen clearance, total hemocyte count, and phagocytic rate were significantly increased in FVP group compared to SA group after the IP and LC treatments. By contrast, no significant changes in antibacterial activity, phagocytic index and phenoloxidase activity (excepting at 6 hpi) were found in the comparison between FVP and SA groups. These results suggested the occurrence of priming phenomenon in mud crab, primary immunization with inactivated V. parahemolyticus can improve survival following infection and enhance cellular immune responses, the particularly phagocytic rate that contributes to the elevated phagocytosis. This finding provides a novel direction in protecting mud crab against vibriosis.

Nanoparticles: An Experimental Study of Zinc Nanoparticles Toxicity on Marine Crustaceans. General Overview on the Health Implications in Humans.

The presence of products containing nanoparticles or nanofibers is rapidly growing. Nanotechnology involves a wide spectrum of industrial fields. There is a lack of information regarding the toxicity of these nanoparticles in aqueous media. The potential acute toxicity of ZnO NPs using two marine crustacean species: the copepod Tigriopus fulvus and the amphypod Corophium insidiosum was evaluated. Acute tests were conducted on adults of T. Fulvus nauplii and C. insidiosum. Both test species were exposed for 96 h to 5 increasing concentrations of ZnO NPs and ZnSO4H2O, and the endpoint was mortality. Statistical analysis revealed that the mean LC50 values of both ZnO NPs and ZnSO4H2O (ZnO NPs: F = 59.42; P < 0.0015; ZnSO4H2O: F = 25.57; P < 0.0015) were significantly lower for Tigriopus fulvus than for Corophium insidiosum. This result confirms that the toxic effect could be mainly attributed to the Zn ions, confirming that the dissolution processes play a crucial role in the toxicity of the ZnO NPs.

Mapping and validation of sex-linked SNP markers in the swimming crab Portunus trituberculatus

Portunus trituberculatus is one of the most commercially important marine crustacean species for both aquaculture and fisheries in Southeast and East Asia. Production of monosex female stocks is attractive in commercial production since females are more profitable than their male counterparts. Identification and mapping of the sex-linked locus is an efficient way to elucidate the mechanisms of sex determination in the species and support the development of protocols for monosex female production. In this study, a sex-averaged map and two sex-specific genetic maps were constructed based on 2b-restriction site-associated DNA sequencing. A total of 6349 genetic markers were assigned to 53 linkage groups. Little difference was observed in the pattern of sex-specific recombination between females and males. Association analysis and linkage mapping identified 7 markers strongly associated with sex, four of which were successfully mapped on the extremity of linkage group 22. Females were homozygous and males were heterozygous for those 7 markers strongly suggesting an XX/XY sex determination system in this species. Three Markers were successfully validated in a wild population of P. trituberculatus and exhibited a specificity ranging from 93.3% to 100%. A high-resolution melting based assay was developed for sex genotyping. This study provides new knowledge and tools for sex identification which will help the development of protocols for monosex female production of P. trituberculatus and support future genomic studies.

An ecosystem services perspective for the economic value of seafood production supported by seagrass ecosystems: An exercise in Derawan Island, Indonesia

Seagrass meadows provide provisioning services that play a vital role in food security and human wellbeing, especially on the small island. However, the utilisation value is uncalculated as support for seafood production and livelihoods for the community, because they are considered as alternative uses, so that seagrass ecosystem services are underestimated and undervalued. This paper aims to show the economic value provided by seagrass ecosystem services in providing seafood, both as a primary or secondary source. Through field survey and effect on production (EOP) analysis shows that capture fisheries and other marine biota collecting, both crustacean and mollusc species associated with the seagrass ecosystem are utilised directly by coastal communities in Derawan Island, Indonesia. Estimates of the economic value of fish and marine biota employed in the seagrass ecosystem area are US$ US$ 13,488.80 and US$ 35,744.69 per hectare per year, respectively, or a total of US$ 49,233.49 per hectare per year. This value demonstrates the potential importance of seagrass ecosystems. Unfortunately, these benefit values have not been fully understood by the communities, so that many people ignore the function of seagrass ecosystem services as provisioning services, although in the scarcity the utilisation of the seagrass ecosystem is quite intensive. Hence, the precautionary principle and suggesting conservation actions in a participatory manner is challenging to implement.

Acute and chronic toxicity of the benzodiazepine diazepam to the tropical crustacean Mysidopsis juniae.

Pharmaceuticals occur in the environment due to their excessive consumption and the inefficiency of treatment plants to degrade, inactivate or remove them. Diazepam (DZP) stands out as the most consumed benzodiazepine, and induces sedative effects and reduces anxiety. Considering its potential appearance in several environmental compartments, the aim of the present study was to determine the effects of DZP under acute and chronic exposures on the mysid Mysidopsis juniae. Mortality was assessed using an acute toxicity test and a LC50 of 3.7 ± 0.5 mg·L-1was derived. The mass and length of the mysids was recorded in the chronic exposure to test for sublethal effects, and concentrations of 0.25 and 0.5 mg·L-1 of DZP affected mysids length and dry weight, respectively. Although effect-inducing concentrations used in this study are above environmentally relevant levels, the present study adds value to the limited available data for DZP toxicity to marine organisms, and we have shown that M. juniae is the most sensitive marine crustacean species tested thus far.

Stock assessment methods on marine crustacean species: A review.

Crustaceans, such as crab, lobster, prawn, and Antarctic krill, have formed a vast and commercially valuable fishery globally. Although the importance and scale of these crustacean fishe-ries are increasing, the suitable and effective methods for stock assessment and management of crustacean fisheries are urgent to be improved compared to other fisheries. We reviewed and evaluated four kinds of stock assessment methods for assessing crustacean fishery, including the surplus production model, delay-difference model, the depletion model, and size-structured model. We described the application of those models in stock assessment of crustacean fishery, and briefly summarized the assumptions and data needed in these models. We further compared the advantages and disadvantages of those models. In addition, the assumptions of the models, the estimation method of the parameters, and the general solution of uncertainty were analyzed. Finally, the future direction and prospect of crustacean stock assessment were discussed.

Development and characterization of 24 SNP markers in Kuruma shrimp (Marsupenaeus japonicus) by illumina sequencing

We performed Illumina-based RNA-Seq for Kuruma shrimp Marsupenaeus japonicus and discovered single-nucleotide polymorphisms (SNPs) markers using de novo assembly transcriptome without reference genome. Totally 43,001 putative SNPs were obtained using Genome Analysis Toolkit (GATK) software from 15684 contigs, furthermore, 9149 contigs were annotated based on Basic Local Alignment Search Tool (BLAST) against GenBank’s non-redundant protein database (NR). Among these, 24 SNPs were validated by PCR amplification of multiple specific alleles (PAMSA) procedure using 30 individuals from Xiamen population. All loci had two alleles and the minor allele frequency ranged from 0.1041 to 0.4583. Expected (H E) and observed (H O) heterozygosities ranged from 0.1866 to 0.5071 and 0.1250 to 0.9167, respectively. This was the first SNP mining study in M. japonicus using high throughout transcriptome technology and provided useful information for future conservation and management of this overexploited marine crustacean species.

Annotated list of species of marine crustaceans (Decapoda and Stomatopoda) from Golfo Dulce, Costa Rica.

The present study is an annotated list of the marine crustaceans (Decapoda and Stomatopoda) from Golfo Dulce, Costa Rica, collected during the RV Victor Hensen Cruise 1993-1994, at depths ranging from 20 to 260 m. Stomatopoda was represented by one family and two species. Decapoda was represented by 12 families and 21 species. Two new records for Costa Rica, Cancer johngarthi and Lysmata californica are reported. This increases the reported marine crustaceans of Golfo Dulce to three species of Stomatopoda and sixty-six of Decapoda (a complete checklist in included). A list of species reported in the literature from the gulf is also included.

The protected taxon Ocypode cursor (Linnaeus, 1758) (Crustacea: Decapoda: Ocypodidae) – documenting its well-established presence in the central Mediterranean

Ocypode cursor (Linnaeus, 1758) is the only Ocypode species present in the Mediterranean Sea, and one of the nine marine crustacean species protected in the basin. It is widely distributed in the eastern Mediterranean, but knowledge about its presence in the central Mediterranean is very limited so far. We hereby first document the established presence of O. cursor in the central Mediterranean (Sicily and Malta), backdate the known presence of this taxon in Italy, and offer preliminary observations on the main known Maltese population. In Sicily, O. cursor is distributed along most of the south-western coast of the island of Sicily, whilst at least three beaches in the Maltese Islands are known to support populations of this species. The main Maltese population exhibits numerous similarities (e.g. burrow width, zonation along the beach) to another Mediterranean population studied in northern Cyprus, although occurring at lower densities. We conclude that the species has been probably present within the study area for a long period, but went undetected in view of the low population densities at which it previously occurred, the lack of a comprehensive census for the species within the same study area, and its nocturnal habits. The presence of this species in the central Mediterranean seems to be attributable to secondary natural spreading.

Biomonitoring of environmental stress in Pollicipes pollicipes from the northern coast of Portugal: a non-destructive approach using haemolymph

In the intertidal area, the interactions between anthropogenic contaminants and natural variations (biotic and abiotic factors) are poorly understood. Consequently, there is a great need for new assessment procedures to characterize the biological responses occurring in organisms from this extreme environment. Considering the intrinsic inter-individual variations among organisms from a single population, it is important to propose new methods that address this variability, by validating a sampling strategy in target groups of organisms, encompassing seasonal fluctuations. This strategy must however be less invasive than traditional methods, avoiding the mandatory sacrifice of the sampled organisms. By doing so, it is also possible to increase the ecological relevance of obtainable data, and contribute to minimize damage to endangered species. The main purpose of the present study was to assess the influence of seasonal variations in the responses elicited by anthropogenic compounds on a marine crustacean species, by using a biomarker-based approach. According to this purpose, the seasonal variations in key physiological responses (biomarkers) were investigated in the crustacean Pollicipes pollicipes from the Northern coast of Portugal. Biomarkers used for this purpose were the activity of the phase II biotransformation isoenzymes glutathione-S-transferases (GSTs), the activity of cholinesterases (ChEs), and the levels of lipid peroxidation (TBARS). All biomarkers were quantified in distinct tissues (such as cirri, and peduncle) and haemolymph (a non-destructive source of biological samples). The glycogen content in peduncle tissue, and the variation in haemocyte number in haemolymph were also analyzed. Samples were collected monthly, during a year, in Lavadores, located in the proximity of an estuarine area (Douro River). The results showed a seasonal pattern in all tested biomarkers. The results also showed a significant increase in GSTs activities, and in peroxidative damage, especially during warmer months. The lowest ChEs values were recorded during the rainy season. The results also showed a similar pattern among all tested tissues, validating the proposed use of the haemolymph as a source tissue for non-lethal sampling strategy for biomarker determinations. Glycogen content was apparently related to the reproductive cycle, with lower values being observed in spring and summer. Total haemocyte count (THC) increased during summer months. The results pointed to an influence of natural variations in the levels of biomarkers in P. pollicipes, highly dependent upon abiotic factors, a factor that must be considered when interpreting biological responses elicited by anthropogenic contaminants from the marine coastal environment. The validation of haemolymph as a non-lethal source tissue for the quantification of biomarkers was successfully attained, opening the possibility of less invasive and almost unlimited sampling in a small number of organisms.

How does the dinoflagellate parasite Hematodinium outsmart the immune system of its crustacean hosts?

Dinoflagellates of the genusHematodinium infect over 40 species of marine crustaceans. Since the initial description of this parasite in France in the 1930s [1], it appears to have spread globally, causing economic loss in some species, including Tanner crabs (Chionoecetes bairdi) in Alaska [2], blue crabs (Callinectes sapidus) in the United States [3], edible crabs (Cancer pagurus) and Norway lobsters (Nephrops norvegicus) in Europe [4–7], sand crabs (Portunus armatus) in Australia [8], and Chinese swimming crabs (Portunus trituberculatus) in northern China [9]. Because this disease is thought to be fatal, it may be of great significance to the sustainability of both captive shellfish fisheries and aquaculture [10,11]. For instance, the decline in blue crabs from the Atlantic to Gulf Coasts in the US appears to be linked to epizootic outbreaks of disease caused byHematodinium [12]. Similarly, the reduction in velvet swimmer crab (Necora puber) numbers in Brittany in the 1980s has been attributed to the high prevalence of such infections [13]. Finally, the recent reports ofHematodinium infections in crabs and shrimp raised under aquaculture conditions in China [9,14,15] highlight the danger to additional, cultured crustacean populations. The number and host range of species ofHematodinium is unclear. Chatton and Poisson [1] identified one species of this parasite that they termed H. perezi. Notably, this species of parasite was reported in two different species of crabs from several locations around the French coast. A second species,H. australis, was first described in sand crabs fromMoreton Bay in Australia [8]. Recent studies making use of the variability of the ITS1 rDNA region ofH. perezi suggest that there are three clades (genotypes), I–III, of this species (see [11] for further details). Pagenkopp Lohan et al. [16] concluded that blue crab populations collected from the Atlantic to the Gulf coasts of the US were all affected by one genotype, H. perezi (III), which implies a large geographic range. Importantly, other species of crabs collected from the same region were also infected by the same genotype of H. perezi [16]. In Europe, there may be two clades of Hematodinium infecting a range of crabs. H. perezi genotype I has been reported in Liocarcinus depurator [17] and Carcinus maenas. The second species ofHematodinium, currently unnamed (Hematodinium sp.) infects a wider range of crustaceans, including edible crabs (C. pagurus). Importantly, these observations imply that this parasite is a host generalist and may be able to “jump” from host species to species, thereby making it a significant threat to a wide variety of commercially important decapods.