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The commercially important Atlantic blue crab, Callinectes sapidus , recruits to bays and estuarine habitats from planktonic megalopal larvae throughout the eastern United States. These megalopae engage in vertical and horizontal swimming to reach a location of primary settlement, most commonly seagrass beds. These benthic habitats provide food and shelter for the megalopae as they metamorphose into juveniles. These benefits may be gained from planktonic association as well. Across 4 years and multiple sites in the Northwestern Gulf of Mexico, we record Callinectes megalopae and small juveniles actively clinging to Chrysaora chesapeakei (the Chesapeake Bay Nettle) medusae. Up to 301 individual megalopae were recorded on a single jellyfish. This establishes that C. chesapeakei is used as transport and temporary nursery habitat by the C. sapidus megalopae. This report brings light to a mid-water interaction of a commercially valuable crustacean and a seasonal scyphozoan that may facilitate juvenile recruitment. [ABSTRACT FROM AUTHOR]

Patterns and processes of species diversification in the oceans are still not fully understood. Traditionally, studies have been using the pelagic larval duration (PLD) to explain the genetic structure and phylogeographic history of marine taxa. However, this trait has given inconsistent results, especially when there is a physiological barrier. Phylogeographic studies comparing species that have similar PLD but differ in other important traits can indicate which ones drive intraspecific evolution. To test our hypothesis, we selected two species with similar distribution and PLD and different salinity tolerance to explore the role of Amazon-Orinoco plume (the biggest freshwater discharge into the ocean worldwide) in the diversification of western Atlantic species. We amplified mtDNA markers (COI and 16S rRNA) of Callinectes ornatus (less tolerant to low salinity) and C. danae (tolerant to low salinity) from both sides of the Amazon-Orinoco plume (four biogeographical provinces). Then, we performed genetic structure, historical demography, divergence time, and biogeographic modelling analyses. Our results show contrasting phylogeographic and demographic patterns that can be explained by salinity tolerance. The Amazon-Orinoco plume represents a barrier for C. ornatus, which has two evolutionary units (ESUs). The plume is not a barrier for C. danae, which has no genetic structure. Furthermore, C. ornatus is formed by an ancestral Caribbean group that dispersed to the southwestern Atlantic after the establishment of the Amazon-Orinoco plume. Callinectes danae has undergone demographic changes during the Last Glacial Maximum, probably due to the loss of estuarine habitats due to sea level fall, while C. ornatus was not affected because it is absent in this type of environment. Therefore, we show that ecological traits of marine taxa, like salinity tolerance, are more reliable predictors of genetic variation than the usually used larval dispersal potential. [ABSTRACT FROM AUTHOR]

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Graphical abstract Highlights • C. bellicosus has a latitudinal gradient in genetic diversity and effective population size. • There is asymmetric northward flow of propagules in this crab metapopulation. • Southern populations are sources, northern populations are sinks. • Northward larval dispersal during spawning explains the genetic structure. • Current fisheries management does not recognize the metapopulation structure. Abstract Management of commercial fisheries resources is commonly done assuming that populations are spatially homogeneous throughout their geographic range. However, uneven gene flow can result in gradients of genetic diversity that can affect population dynamics and management reference points and may contribute to overfishing. We examined whether the brown swimming crab, Callinectes bellicosus , fished along 1200 km on the coast of Sonora (Mexico) is a homogeneous population. Based on previous empirical evidence of differences in phenology, we hypothesized that C. bellicosus has a metapopulation structure which needs to be included in management tools. We conducted a genetic study of C. bellicosus taken at seven sites along the coast of Sonora and obtained their microsatellite genotypes. Recent gene flow, as well as the role of each site as source or sink, were investigated. We found a latitudinal gradient in genetic diversity and identified sites along the coast acting as sources or sinks of migrants. Central sites act as sources, while northern sites are sinks; the main source of migrants was the southern-most site. A predominantly asymmetric metapopulation structure composed of local populations with moderate connectivity may be explained by larval dispersal in the northward oceanic current during the spawning period. Including migration rates between sites in a metapopulation dynamics model of C. bellicosus and considering that fishing and management decisions in source populations will impact neighboring populations located downstream can improve current management of this important commercial fishery. [ABSTRACT FROM AUTHOR]

The bioavailability and bioaccumulation of sedimentary hydrophobic organic compounds (HOCs) is of concern at contaminated sites. Passive samplers have emerged as a promising tool to measure the bioavailability of sedimentary HOCs and possibly to estimate their bioaccumulation. We thus analyzed HOCs including organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and polychlorinated dibenzo‐p‐dioxins/furans (PCDD/Fs) in sediment, porewater, and river water using low‐density polyethylene passive samplers and in 11 different finfish species and blue crab from the lower Passaic River. In addition, perfluorinated alkyl acids (PFAAs) were measured in grab water samples, sediment, and fish. Best predictors of bioaccumulation in biota were either porewater concentrations (for PCBs and OCPs) or sediment organic carbon (PBDEs and PFAAs), including black carbon (OCPs, PCBs, and some PCDD/F congeners)–normalized concentrations. Measured lipid‐based concentrations of the majority of HOCs exceeded the chemicals' activities in porewater by at least 2‐fold, suggesting dietary uptake. Trophic magnification factors were >1 for moderately hydrophobic analytes (log octanol–water partitioning coefficient [KOW] = 6.5–8.2) with low metabolic transformation rates (<0.01 d−1), including longer alkyl chain PFAAs. For analytes with lower (4.5–6.5) and higher (>8.2) KOWs, metabolic transformation was more important in reducing trophic magnification. Environ Toxicol Chem 2019;38:872–882. © 2019 SETAC [ABSTRACT FROM AUTHOR]

This technical note aims to report, in detail, the development, suitability and analytical validation of an artificial food to assess metal bioaccumulation in the blue crab Callinectes danae after metal exposure assays. For this purpose, lead (Pb) was chosen as the metal of interest. First, a non-contaminated artificial food was prepared by mixing commercial shrimps and agarose. The food was then offered on alternate days to two groups of crabs for 7 and 14 days, respectively. After confirming that this food was well-accepted by crabs, analytical procedures were performed to confirm that Pb added to the mixture would remain in the artificial food. For this purpose, two foods containing Pb at concentrations of 0.5 and 2.0 µg g−1 were prepared by adding aliquots of an ultrapure Pb standard solution to the mixture. Samples of each food were subjected to an acid extraction and Pb concentrations were determined by a GF-AAS. Pb recoveries in both contaminated foods were > 90%. Subsequently, another experiment was performed, and two groups of crabs were fed with contaminated artificial foods (0.5 and 2.0 µg g−1 of Pb) during 7 and 14 days, respectively. The observed acceptance of these foods by crabs at both Pb concentrations was of 100%. Article Highlights: An artificial food was prepared to assess bioaccumulation in the blue crab Lead (Pb) was chosen as the metal of interest The acceptance of artificial food was evaluated In the contaminated artificial foods, Pb was determined It was concluded that this food can be applied in metal exposure assays [ABSTRACT FROM AUTHOR]

Abstract Crustacean aquaculture is prone to mortality from the combined effects of disease agents and the stresses associated with crowded, closed conditions. The culture practice of producing soft-shell blue crabs is no exception, suffering from mortality of about 25%. The virus, Callinectes sapidus reovirus 1 (CsRV1), has been reported at high viral loads in crabs dying in soft-shell shedding facilities. We investigated the relationship between crab mortality and CsRV1 prevalence and load in soft-shell crab production and whether death and virus infection correlated with identifiable aquaculture practices, environmental stresses, crab characteristics, or geographic regions. The patterns of CsRV1 prevalence, infection intensity, and mortality in blue crab aquaculture were studied in the Chesapeake Bay and Gulf of Mexico, USA. Using a genome-targeted assay, we compared virus loads in live and dead aquaculture crabs by individual sex and injury state from recirculating and flow-through systems of variable salinity, temperature, and crabs per aquaculture tank. Mortality was two-fold higher in flow-through aquaculture systems (33%) than in recirculating aquaculture systems (16%). Flow-through aquaculture systems had higher daily water temperature variability than recirculating aquaculture, and hypoxic events were observed only in flow-through systems during this study. High CsRV1 intensity was found in 62% of all pre-molt mortalities in production compared with 7% of successfully molted soft-shell crabs. The CsRV1 virus load in dead crabs was elevated in higher salinity conditions. In a mixed-effect model analysis, the random effects of location and time were more significant than salinity in predicting CsRV1 load in all crabs and dead crabs. Our results support previous research showing that recirculating aquaculture has lower mortality in soft-shell production, and confirms the association of high viral loads of CsRV1 with crab mortality in these production systems. Moreover, the findings indicate that although CsRV1 is ubiquitous in these systems, management of culture conditions such as salinity and temperature may limit virus-associated mortality. Highlights •.A study of US soft crab producers showed that 16% of peelers die before molting in recirculating systems, and 33% die in flow through systems. • The pathogenic virus, CsRV1, was present at high levels in most crabs that died in soft-shell production and in 7% of successfully molted crabs. • Virus in dead crabs was associated with lower salinity, but random effects of location and date were also associated with prevalence and load. • Though CsRV1 is ubiquitous, management of culture conditions (e.g., salinity and temperature variation) may limit virus-associated mortality. [ABSTRACT FROM AUTHOR]

The access to updated data on the names of the crustacean species and their distribution in a given area is a first step to evaluate changes due to local, regional and global factors such as overfishing, pollution, and climatic change. Data in this study are based on the expeditions of the RV Skimmer (20 stations, 1979-1980) and RV Victor Hensen (1993-1994, 12 stations) in the Gulf of Nicoya estuary. The crustaceans were collected by means of an Otter trawl (Skimmer, mesh 3.5 cm) and by Otter and Beam trawls (V. Hensen, mesh 2.5 cm and 1.0 cm, respectively) at depths from 10 m to 228 m. Data from two later studies were also included, one from an intertidal flat in the upper Gulf and the other from stations at the mouth of the estuary, which expand the depth range from 0 to 350 m. The list of species in the original publications were updated and 32 corrections were made based on recent literature and the web page, World Register of Marine Species (WORMS). The total number of species for both surveys was 131, of which 119 were decapods and 12 were stomatopods. Data from the other two studies and from the crustacean collection deposited at the University of Costa Rica Zoology Museum added 43 records for a total of 174 species collected in sediments from the estuary. For the Skimmer, the minimum number of species found in one station was four (three stations) and the maximum was 27, with an average of 12.3 species / station. For the V. Hensen, the minimum of species found in one station was eight, with a maximm of 27 and an average of 17 species / station. The species present in 50% or more of the 20 stations of the Skimmer expedition, were: Callinectes arcuatus, Rimapenaeus faoe, Penaeus brevirostris, Achelous asper and Hepatus kossmanni. For the V. Hensen expedition, the species present in 50% or more of the 12 stations, were: A. asper, Sicyonia disdorsalis, S. picta, and Persephona subovata. During the Skimmer survey a total of 15 species were found at only one station, while for the V. Hensen the number was 26. Two presence-absence matrices based on the updated names of the crustaceans collected by the Skimmer (57 species x 20 stations) and V. Hensen (82 species x 12 stations) were analyzed by Non Metric Dimensional Scaling (NMDS) to display the distribution of stations in a two-dimensional space. The results revealed heterogeneous groups of stations. Several sub-groups of two or three stations agreed with their geographical proximity. The four V. Hensen stations, located at the mouth of the estuary at depths greater than 60 m, were separated more clearly from the others and may indicate a transition, from estuarine to deep waters, in the composition of the crustacean fauna. Future evaluations of the crustacean diversity of the Gulf of Nicoya must take into account the wide spatial distribution of some species and the patchy distribution of others. Temporal variability is also important in the estuary as evidenced by the population oscilallations of Pinnixulala valerii over a three year period. [ABSTRACT FROM AUTHOR]

Abstract Pot fisheries occur worldwide with a significant proportion of the gear becoming derelict. Derelict pots induce detrimental ecological and economic impacts, and more recently were found to reduce blue crab harvests in the Chesapeake Bay commercial fishery. We simulated the presence of derelict pots near actively fished pots in seasonal field experiments to quantify the effect derelict pots have on blue crab harvest. Derelict pots reduced harvests by 30% during the summer, but not during the fall. Female blue crab capture rates were consistently lower when derelict pots were present; while capture rates of the less abundant males were not negatively affected by derelict pots. Variable responses to derelict pots may be due to seasonal differences in female and male blue crab behavior and movements. The costly effect that derelict pots have on harvest should be investigated in other pot fisheries to recognize the magnitude and mechanisms behind these impacts. Highlights • Derelict blue crab pots can reduce harvests in actively fished pots. • The effect of derelict pots on harvest differs seasonally. • Reduced harvests due to derelict pots were more evident in female blue crabs. [ABSTRACT FROM AUTHOR]

Temperature can impact many processes in ectotherms. With global temperatures rising due to climate change, many ectotherms may exhibit changes in growth rates and size at maturity, and these changes can have population-level effects. Predicting responses of species to climate change will require not only knowledge of thermal-tolerance limits, but also effects of temperature change on growth rates and other life-history parameters. For arthropods that exhibit discontinuous growth (i.e. molting), this includes both intermolt period and growth per molt. Previous laboratory and field experiments suggest that temperature affects both intermolt period (IMP) and growth per molt (GPM) in many crustaceans. We investigated the effect of temperature on the growth process in the lesser blue crab Callinectes similis Williams, 1966 to examine differences in temperature sensitivity of growth rates. Crabs reared under elevated temperatures exhibited decreased intermolt period (IMP) and growth per molt (GPM), resulting in smaller sizes at each instar. If this pattern continued through the pubertal molt, elevated temperatures would result in smaller size at maturity. [ABSTRACT FROM AUTHOR]

A large number of coastal ecosystems globally are subjected to concurrent hypoxic and acidified conditions that will likely intensify and expand with continued climate change. In temperate regions, the spawning of many important organisms including the Atlantic blue crab Callinectes sapidus occurs during the summer months when the severity of coastal hypoxia and acidification is the greatest. While the blue crab earliest larval stage can be exposed to co-occurring hypoxia and acidification observed in many coastal ecosystems, the effects of these concurrent stressors on larval blue crab survival is unknown. This study investigated the individual and combined consequences of low dissolved oxygen (DO) and low pH on blue crab larvae survival through a series of short-term experiments. During 14-day experiments with moderately hypoxic conditions (117–127 μM O2 or 3.74–4.06 mg L-1) and acidified conditions (pH on total scale of 7.16–7.33), low DO and low pH individually and significantly reduced larval survival by 60% and 49%, respectively, with the combination of stressors reducing survival by 87% compared to the control treatment (210–269 μM O2 or 6.72–8.61 mg L-1, 7.91–7.94 DO and pH, respectively). During 4-day experiments with lower DO levels (68–83 μM O2 or 2.18–2.62 mg L-1) and comparable pH levels of 7.29–7.39, low DO individually reduced survival by >90% compared to the control (261–267 μM O2 or 8.35–8.54 mg L-1, 7.92–7.97 DO and pH, respectively), whereas low pH had no effect and there was no interaction between stressors. Over a 4-day period, the DO threshold at which 50% of the larval blue crab population died (LC50) was 121 μM O2 (3.86 mgL-1). In 14-day experiments, the DO and pH effects were additive, yielding survival rates lower than the individual treatments, and significantly correlated with DO and pH concentrations. Collectively, these findings indicate that blue crab sensitivity to both low DO and low pH are acute within the larval stage, depend on the intensity and duration of exposure, and leads to mortality, thereby potentially contributing to the interannual variability and possible regional declines of this fishery. [ABSTRACT FROM AUTHOR]

This work analyses how the fecundity of the brown swimming crab, Callinectes bellicosus , varies along the coast of Sonora in the Gulf of California. Ripe female crabs were collected during May 2015 in four zones, and fecundity was determined and compared with carapace width (CW), total body weight (TW) and egg mass weight (MW). TW ranged between 100.5 g and 209.8 g (average = 158.2 g, coefficient of variation (CV) = 23.4%); CW ranged from 97.9 mm to 123.6 mm (average = 113.4 mm, CV = 8.3%); MW varied from 16.4 g to 34.1 g (average = 25.3 g, CV = 20.4%). The total fecundity (number of eggs per female) of C. bellicosus varied from 1 769 195 to 3 739 254 (average = 2 730 217, CV = 22.2%); partial fecundity (number of eggs per g of egg mass) ranged from 100 422 to 117 130 (average = 107 721, CV = 5.1%). A general north-south decrease in fecundity was observed, although the least fecund females were found in central Sonora (Kino Bay). The most significant linear correlation was found between total fecundity vs. egg mass weight. Total fecundity was better explained by a Von Bertalanffy model, with a maximum average fecundity of 3.7 million eggs for a female of 230 g total weight. [ABSTRACT FROM AUTHOR]

External morphology has been shown to influence predation and locomotion of decapod larvae and is, therefore, directly related to their ability to survive and disperse. The first goal of this study was to characterize first-stage blue crab zoeal morphology and its variability across larval broods to test whether inter-brood differences in morphology exist. The second was to identify possible correlations between maternal characteristics and zoeal morphology. The offspring of 21 individuals were hatched in the laboratory, photographed, and measured. Zoeae exhibited substantial variability, with all metrics showing significant inter-brood differences. The greatest variability was seen in the zoeal abdomen, rostrum, and dorsal spine length. A principal component analysis showed no distinct clustering of broods, with variation generally driven by larger zoeae. Using observed morphology, models of drag induced by swimming and sinking also showed significant inter-brood differences, with a maximum twofold difference across broods. In contrast to trends in other decapod taxa, maternal characteristics (female carapace width and mass and egg sponge volume and mass) are not significant predictors of zoeal morphology. These results suggest that brood effects are present across a wide range of morphological characteristics and that future experiments involving Callinectes sapidus morphology or its functionality should explicitly account for inter-brood variation. Additionally, inter-brood morphological differences may result in differential predation mortality and locomotory abilities among broods. [ABSTRACT FROM AUTHOR]

The academic interest in the production of soft‐shell swimming crabs has increased in direct proportion to the increasing demand worldwide for this gastronomic delicacy. The techniques of obtaining this product are essentially based on the maintenance of swimming crabs at premoult stage in open, semi‐closed or closed farming systems, until the moment of moulting. These different types of systems reflect the biological e environmental control method evolution. To achieve industrial scale production of soft swimming crabs, the option of using closed systems has increased in recent years. This type of system offers several advantages, such as greater control over environmental variables, greater ease of installation, higher storage densities, greater ease of monitoring ecdysis occurrence and, especially, the possibility of incorporating several forms of automation. In this review, the main production systems currently used, as well as the main techniques for obtaining the animals, their management under controlled conditions, harvesting and slaughter, are presented and discussed, focusing on future perspectives for the world production of soft‐shell swimming crabs. [ABSTRACT FROM AUTHOR]

Crabs are encased in a rigid exoskeleton or cuticle that is hardened by both protein crosslinking and calcification. In order to grow, the exoskeleton must be periodically molted. The two outermost layers of the exoskeleton of crabs are deposited prior to the molt, but remain uncalcified until the animal sheds its old exoskeleton. The inhibition of premolt calcification and initiation of postmolt calcification are effected by biochemical changes in the organic matrix. In the 2 h after the molt, sugar moieties are enzymatically altered on cuticular glycoproteins by an N-acetylhexosaminidase secreted by the underlying epithelium. These alterations appear to unmask nucleation sites that allow calcification to commence. The initial deposition of mineral is in the form of amorphous calcium carbonate (ACC). As postmolt calcification continues and the principal layer (endocuticle) is deposited and mineralized, the ACC is largely converted to or overgrown by calcite. Prior to the onset of ACC deposition, silicon has been detected in those areas of the exoskeleton that are about to undergo mineralization. As calcification proceeds, silicon is no longer detected. It is hypothesized that silicon is involved in the stabilization of ACC by destabilizing the crystal lattice of calcite before it undergoes the transition to or is overgrown by crystalline calcite.

This study aimed to assess the bioaccumulation of Pb and induction of metallothionein-like proteins (MT) in Callinectes danae through single and combined dietary and waterborne exposures. Male C. danae individuals were collected in the south area of the Cananéia-Iguape-Peruíbe Protected Area (APA-CIP), in São Paulo State, Brazil. After an acclimatization period, exposure assays were performed during 7 and 14 days, at two Pb concentrations (0.5 e 2.0 µg/g) in 4 treatments: 1) control; 2) contaminated water only; 3) contaminated food only; 4) contaminated water and food. The results indicate that C. danae is highly tolerant to Pb exposure at the evaluated concentrations. In gills, Pb bioaccumulation is more dependent of water efflux and time of exposure (higher Pb values). However, pathways act simultaneously in the induction of MT expression in this tissue. The decreases in Pb accumulation in the combined treatments and MT increases after 14 days in gills suggests that these proteins play a detoxification function in the presence of Pb. In hepatopancreas, depending on the predominance of a certain pathway or combined pathways, accumulation occured at different times. For muscle tissue, bioaccumulation was observed due to contaminated water exposure, but not dietary exposure, probably because Pb concentrations were low. [ABSTRACT FROM AUTHOR]

Survival, osmoregulatory pattern, oxygen consumption, energy spent on metabolism, ammonia excretion, type of oxidized energy substrate, and hepatosomatic index were evaluated in decapods (an osmoregulating crab, Callinectes danae, and an osmoconforming seabob shrimp, Xiphopenaeus kroyeri) exposed to carbon dioxide-induced water acidification (pH 7.3, control pH 8.0) and different salinities (20, 25, 30, 35, and 40‰) for 3 days. Compared to the animals kept at controlled pH, exposure to reduced pH resulted in the loss of osmoregulatory capacity in C. danae at all salinities, except for some hyporegulation at 40‰, and reduced oxygen consumption and ammonia excretion at 20 and 40‰. Xiphopenaeus kroyeri remained an osmoconformer in all evaluated conditions, except for some hyporegulation at 40‰, and when exposed to the reduced pH, it presented changes in oxygen consumption at all salinities and reductions in ammonia excretion at 20 and 35‰ compared to the control animals. Both species use protein as the main energy substrate and decrease the hepatosomatic index when exposed to reduced pH relative to the control. The observed changes may be associated with changes in the activity of enzymes related to osmoregulation, the use of amino acids as osmotic effectors of cell volume control and recovery, and the Bohr effect, and, because the gills are multifunctional organs related to osmoregulation, the changes may be related to acid-base control, nitrogen excretion, and respiration, with a change in one of these functions bringing about changes in the others. [ABSTRACT FROM AUTHOR]

In Mexico, swimming crabs are considered a strategic resource because it supports artisanal fishing when the main fish resource (shrimp) is in closed season. In “Marismas Nacionales” the blue crab fishery is relatively new, and the catches have been maintained due to the national demand and the availability of the resource. Individual growth, sexual maturity, sexual ratio and mortality were estimated for Callinectes arcuatus for providing information about its population dynamics. Samplings were carried out every 10 days from October 2002 to November 2003. A total of 6022 specimens of C. arcuatus were collected (70.05% were males and 29.95% females) with a maximum carapace width (CW) of 138.5 mm in males and 118.7 mm for females. For males, case 5 of the Schnute model was the best model for describing the individual growth (k=0.97 year−1 and ε=196 mm), while case 2 (k=3.11 year−1 and ε=121.6 mm) was a better fit for females. The size at sexual maturity was 88.9 mm CW in males (CI = 88-90 mm) and 82.2 mm CW in females (CI = 81.7-82.9 mm). The estimated age at sexual maturity was 0.79 and 0.91 years for males and females, respectively. The male/female sex ratio was 1 : 0.43, significantly different (p<0.001, χ2=969) from the theoretical sexual ratio (1 : 1). Mortality rates in males were M=1.63, Z=2.43 and F=0.80, and in females they were M=1.46, Z=2.56 and F=1.10. The exploitation rate indicated the resource is below the optimum level of exploitation and the maximum yield per recruit. [ABSTRACT FROM AUTHOR]

The blue crab Callinectes sapidus is an alien decapod established in the Mediterranean Sea. Since 2007, increased abundance has been reported from the northern Aegean Sea sustaining local scale fishery. The present work aims to assess the abundance and population structure of C. sapidus in Thermaikos Gulf using fyke nets. Population abundance, estimated as CPUE, exhibited strong temporal variability with decreased values in the cold season; this pattern was correlated with seawater temperature. Females exhibited also spatial differences with increased abundance close to the Aliakmon estuary. In total, 543 individuals were measured for carapace width. Males prevailed in the population; however, mean size was similar between sexes. Larger individuals were caught from deeper waters and the estuarine areas, whereas mean size decreased temporally. The fyke nets used proved to be size-selective, thus preventing fisheries mortality for juveniles. However, recurrent monitoring is necessary for a sustainable management of blue crab fisheries in the gulf. [ABSTRACT FROM AUTHOR]

The introduction of species is a major threat to biodiversity conservation. Island biodiversity is especially sensitive to the arrival of new species, and species introductions are one of the major concerns of conservation management policies. Here, we report for the first time the arrival of Callinectes sapidus, a new potentially invasive crab species from the East coast of America to the Balearic Islands (Spain). It appeared simultaneously in both Mallorca and Menorca islands. Nine different records of 20 individuals were documented in six different localities, suggesting an initial colonization process of the territory. [ABSTRACT FROM AUTHOR]

The consumption of sea food especially crabs in the Niger Delta is an indelible aspect of the culinary culture of the people and a veritable avenue to contracting zoonotic infections. A comparative analysis of the parasitic fauna status of two edible crabs; C. armatum from the New Calabar River and the marine crab; C. amnicola from the Elechi Creek was conducted from March to June, 2016. The physico-chemical parameters of the water samples were determined using standard techniques. The samples were dissected and the hemolymph, the appendages, gill, mouth parts and eye, carapace and gastrointestinal tract (GIT) examined. 147 samples of C. amnicola comprising of 79 (53.74%) males and 68 (46.26%) females were sampled while 123 samples of C. armatum comprising of 59 (47.96%) males and 64 (52.03%) female were also sampled. Data revealed that out of the 147 C. amnicola sampled, 61(41.49%) were infected while 63 (41.50%) were infected out of the 123, C. amnicola sampled. Sex related prevalence showed that C. amnicola, females had higher prevalence when compared to the males. However, C. armatum, males had a higher prevalence when compared to the females although the prevalence between the sexes was not statistically significant (p>0.05). There was variability in the parasite load across the sets of infections with the gastrointestinal tract, hemolymph and gills while the least infected sites were the mouthparts/eyes and appendages in both species of crabs. Also, protozoa had the highest prevalence in C. amnicola while nematodes had the highest prevalence in C. armatum. There were also variation in parasitic infection in relation to weight, width and length. The study is of the opinion that blue crabs and land crabs from new Calabar River and Elechi Creek were heavily infected with parasites and should be adequately cooked before consumption. The study also opines that public awareness campaigns should be more regular to educate the riverine residence on current waste management strategies. [ABSTRACT FROM AUTHOR]

Coastal marine and estuarine environments are experiencing higher average temperatures, greater frequency of extreme temperature events, and altered salinities. These changes are expected to stress organisms and increase their susceptibility to infectious diseases. However, beyond these generalities, little is known about how environmental factors influence host-pathogen relationships in the marine realm. We investigated the prevalence and intensity of infections by Vibrio cholerae, V. parahaemolyticus, and V. vulnificus in blue crabs, Callinectes sapidus , from Louisiana saltmarshes in relation to temperature and salinity. We evaluated relationships for single measurements taken at the time of collection and for more complex measurements representing accumulated exposure to physiologically-stressful environmental conditions for up to 31 days prior to collection. We found that: (1) prevalence of infection varied across the Louisiana coast, (2) prevalence of all three Vibrio species was influenced by temperature and salinity, and (3) measurements that represent accumulated exposure to extreme conditions are useful predictors of infection prevalence and can provide insights into underlying biological mechanisms. [ABSTRACT FROM AUTHOR]

Total mercury (Hg; ppm dry weight) was measured in blue crabs, Callinectes sapidus , collected from Narraganset Bay and adjacent coastal lagoons and tidal rivers (Rhode Island/Massachusetts, USA) from May to August 2006–2016. For juvenile crabs (21–79 mm carapace width, CW), total Hg was significantly greater in chelae muscle tissue (mean ± 1 SD = 0.32 ± 0.21 ppm; n = 65) relative to whole bodies (0.21 ± 0.16 ppm; n = 19), and irrespective of tissue-type, crab Hg was positively related to CW indicating bioaccumulation of the toxicant. Across a broader range of crab sizes (43–185 mm CW; n = 465), muscle Hg concentrations were significantly higher in crabs from the Taunton River relative to other locations (0.71 ± 0.35 ppm and 0.20 ± 0.10 ppm, respectively). Spatial variations in crab Hg dynamics were attributed to habitat-specific Hg burdens of their prey, including bivalves, gastropods, polychaetes, and shrimp. Prey Hg, in turn, was directly related to localized sediment Hg and methylmercury conditions. Biota-sediment accumulation factors for crabs and prey were negatively correlated with sediment organic content, verifying that organically-enriched substrates reduce Hg bioavailability. From a human health perspective, frequent consumption of crabs from the Taunton River may pose a human health risk (23% of legal-size crabs exceeded US EPA threshold level); thus justifying spatially-explicit Hg advisories for this species. [ABSTRACT FROM AUTHOR]