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Land hermit crabs are a group of shell-carrying crabs that have evolved remarkable terrestrial adaptations in behavior, morphology, physiology, and biochemistry. However, the genetic mechanisms underlying these adaptations remain unclear. In addition, usually it is very difficult to get good genome assemblies for crustaceans. In this study, we managed to assemble the first chromosome-level genome for a land hermit crab (Coenobita brevimanus) with careful manual curation. The final assembly spans 4.74 Gb, with the contig N50 of 1.75 Mb and scaffold N50 of 42.95 Mb, encompassing 117 chromosomes that account for 96.54% of the genome. The evaluations including genome BUSCO (95.26%), Merqury qv (35.88) and the mapping ratio of pair-end short reads (99.48%) showed the high-continuity of C. brevimanus genome assembly, making it the genome with the highest quality in crustaceans with genome size bigger than 3 Gb. The availability of this chromosome-scale genome of crustaceans represents a valuable resource for the land hermit crab, which represents an independent water-to-land transition evolutionary event in the animal kingdom. [ABSTRACT FROM AUTHOR]

ABSTRACT The red rock crab, Cancer productus, is primarily harvested by a recreational fishery, with a small commercial harvest in California. Although relatively large, meat yields are low because the legs are small, and meat is largely confined to the claws. We investigated the potential for a claw‐only harvest for this species. Although hand removal is used in the stone crab fishery, it caused > 90% post‐harvest mortality in red rock crabs. Inducing autotomy by inserting a spike into the arthrodial membranes or by cutting into the autotomy plane resulted in a high post‐harvest survival. We recommend a minimum harvest size of 35 mm claw height to produce a claw size similar to medium‐sized stone crabs and standard‐sized brown and Jonah crabs and to ensure that severed claws are unlikely to have come from female crabs, which is important for regions that mandate a male‐only harvest. [ABSTRACT FROM AUTHOR]

Environmentally explicit models can improve model performance and our understanding of biological processes. However, these models must be retested over time, as the mechanisms influencing biological processes can change. The relationship between recently settled young‐of‐year (i.e., settlers) and pre‐recruit American lobsters was revisited to determine if our perception on post‐settlement lobster processes has changed. Analyses were focused within the southern region of the species' latitudinal range (Rhode Island, United States), where several environmental factors have been theorized to contribute to the Southern New England stock decline and continued depleted state. The inclusion of additional, recent years' data provided insight on how the density‐dependent nature of the settler–pre‐recruit lobster relationship has varied over time. Including both new and retested environmental drivers reaffirmed the importance of incorporating environmental data when describing this process. Specifically, modeling revealed the importance of epizootic shell disease, finfish predators, and Asian shore crabs in the settler–pre‐recruit relationship. Including disease, predation, and competition metrics in the lobster post‐settlement relationship has allowed for improved modeling and insight into settlement dynamics. This renewed analysis supports reevaluating environmentally explicit models over time and calls for further directed research regarding the biological processes we seek to model with time series data. [ABSTRACT FROM AUTHOR]

Introduction: Fluctuations in water quality characteristics influence the productivity of blue crabs (Callinectes sapidus), and the risk of human exposure to pathogenic Vibrio species. Thus, this study assessed the prevalence of total and pathogenic/clinical markers of Vibrio parahaemolyticus and Vibrio vulnificus in blue crabs and seawater from the Maryland Coastal Bays (MCBs) and the correlation between Vibrio levels and physicochemical parameters. Methods: Three to five crabs and 1 L of seawater were collected monthly for 3 years (May 2018 to December 2020) from six sites within the MCBs. Hemolymph and crab tissue were extracted and pooled for each site. Extracted hemolymph, crab tissue, and seawater were analyzed for V. parahaemolyticus and V. vulnificus using the Most Probable Number (MPN) and real-time PCR methods. A one-way Analysis of Variance (ANOVA), correlations, and linear models were used to analyze the data. Akaike Information Criterion (AICc) was evaluated to determine the model that provides the best fit to the data relating to Vibrio concentrations and environmental factors. Results: Results suggested that environmental factors could influence the growth of Vibrio spp. Both V. parahaemolyticus and V. vulnificus were more prevalent during the warmer months than colder months. Vibrio was more prevalent in crab samples compared to seawater. Vibrio vulnificus concentrations in seawater and hemolymph were positively correlated with temperature (p = 0.0143 seawater) and pH (p = 0.006 hemolymph). A negative correlation was observed between the concentration of V. vulnificus in whole crab (tissue) and dissolved oxygen level (p = 0.0256). The concentration of V. parahaemolyticus in seawater was positively correlated with temperature (p = 0.009) and negatively correlated with dissolved oxygen (p = 0.012). Discussion: These results provide current information on the spatial and temporal distributions of Vibrio spp. in the MCBs that are useful for implementing more efficient processing and handling procedures of seafood products. [ABSTRACT FROM AUTHOR]

Understanding the feeding behavior of Portunidae crabs with different baits can improve bait selection and is crucial for improving the effectiveness of crab fishing gear. This study, conducted in indoor experimental tanks, used trajectory tracking software and two types of natural baits (mackerel (Scomber australasicus) and squid (Uroteuthis chinensis)) to understand the behavior of Portunus sanguinolentus and Charybdis natator. Spatial distribution results showed that P. sanguinolentus was frequently present in the starting area (S1) and bait area (S3) in the control and treatment groups. However, C. natator was frequently present and concentrated in the S1 area compared to the middle areas S2 and S3, and only in the mackerel treatments were they observed to move to the S3 areas. The spatial distribution results indicate that P. sanguinolentus shows a stronger willingness to explore its surroundings, while C. natator is generally in a stationary, wait-and-see state. The swimming speeds of P. sanguinolentus and C. natator showed different trends. P. sanguinolentus showed continuous movement with no fixed speed when no bait was present in the control groups. However, when treated with mackerel and squid, the average swimming speed of P. sanguinolentus was faster (>5 cm/s) in the first 10 min and showed a more stable movement speed when searching for the baits. C. natator showed a stationary or low movement speed when no bait was present in the control groups. However, when C. natator perceived the presence of the baits in the treatment groups, their movement speed increased in the first 10 min. In addition, there was no significant difference between male and female crabs of P. sanguinolentus and C. natator in movement speed in the control and treatment groups. Compared to C. natator, P. sanguinolentus might be more sensitive to natural baits, as shown by its movement from S1 to S3. The results indicate that the species of Portunidae crabs show different bait selections. Natural baits (mackerel and squid) are recommended for catching P. sanguinolentus in crab fisheries. [ABSTRACT FROM AUTHOR]

To investigate the effects of predation by the paddle crab Charybdis japonica on the culture and survival of scallops (Mizuhopecten yessoensis) during bottom culture, we investigated the behavioral characteristics of three sizes (small, medium, and large) of scallops in response to exposure to crabs. We found that scallops escaped from crab predation by continuous shell closure or movement. Shell closure force increased with scallop size, and scallops of the same size that were stimulated by the presence of crabs closed their shell more frequently than control scallops. We also measured the activities of superoxide dismutase, catalase, arginine kinase, and octopine dehydrogenase in the gill, adductor muscle, and mantle of scallops before and after exposure to predation. Tissues that showed significant differences between control and test specimens were selected for deep sequencing of the transcriptome to identify and validate the key genes that were sensitive to predation. We found that when M. yessoensis is stimulated by the presence of predators, its behavioral characteristics and related physiological and ecological indexes undergo significant changes. The results are relevant for developing specifications for M. yessoensis seedling casting during bottom culture. [ABSTRACT FROM AUTHOR]

Crustaceans are a valuable resource globally, both ecologically and economically, and investigations into their health are becoming increasingly important as exploitation rises. The microbiome plays a crucial role in crustacean immunity, and understanding its composition and structure can provide insights into the health of an organism and its interactions with various factors. In this study, we investigated the hepatopancreas microbiome of the velvet swimming crab, Necora puber, and compared its composition and structure with several study factors, including two different sampling points and infection with a paramyxid parasite, Paramarteilia canceri. To our knowledge, we provide the first description of a velvet crab microbiome, highlighting the dominance of a single microorganism, Candidatus hepatoplasma. We identified variations in microbiome composition between sampling points and discussed the possible processes affecting microbiome assembly. We also outline a core microbiome for the velvet crab hepatopancreas, consisting of 12 core phyla. Our study adds to the growing literature on crustacean microbiomes and provides a baseline for future investigations into the velvet crab microbiome and the health of this crustacean species. [ABSTRACT FROM AUTHOR]

We present the first report of the Peruvian Fiddler Crab, Leptuca tallanica (von Hagen, 1968), in Panama. The species identification from two sites in the Parita Gulf was confirmed by the presence of a moderately wide front, comma-shaped patches of pile on the male carapace, a pilous triangular depression at the base of the pollex, and a strong, tuberculate projection subdistally on the pollex. Our findings extend the previously known distribution range in the eastern Pacific from southern Ecuador and northern Peru northward to Panama. [ABSTRACT FROM AUTHOR]

Fosfomycin has been used to treat carbapenem‐resistant Acinetobacter baumannii (CRAB) infections. However, there is insufficient information on dosage adjustment among critically ill patients with renal impairment. This study aims to evaluate the attainment of PK/PD targets for different dosage regimens of CRAB treatment in critically ill patients based on their renal function. Monte Carlo simulations were conducted to assess the probability of achieving time above the minimum inhibitory concentration (T > MIC) of 80% and 100% and to determine the cumulative fraction response (CFR) against institutional MICs. Our results demonstrated that administering fosfomycin 20–24 g/day to individuals with normal renal function (CrCl ≥60 mL/min) achieved the target at a MIC of ≤64 and ≤32 μg/mL during the first 24 h of treatment and at steady state, respectively. Notably, those with renal impairment achieved higher MIC values at a steady state despite dosage reduction. None of the regimens reached the target CFR. Our study suggested that administering fosfomycin at least 20 g/day to those with normal renal function provides sufficient exposure throughout the treatment course when the MIC value is ≤32 μg/mL. Less aggressive dosing regimens are advisable for patients with renal impairment. Additional clinical studies are necessary to verify our suggestions. [ABSTRACT FROM AUTHOR]

Motion vision is vital for a wide range of animal behaviors. Fiddler crabs, for example, rely heavily on motion to detect the movement of avian predators. They are known to detect first-order motion using both intensity (defined by spatiotemporal correlations in luminance) and polarization information (defined separately as spatiotemporal correlations in the degree and/or angle of polarization). However, little is known about their ability to detect second-order motion, another important form of motion information; defined separately by spatiotemporal correlations in higher-order image properties. In this work we used behavioral experiments to test how fiddler crabs (Afruca tangeri) responded to both second-order intensity and polarization stimuli. Fiddler crabs responded to a number of different intensity based second-order stimuli. Furthermore, the crabs also responded to second-order polarization stimuli, a behaviorally relevant stimulus applicable to an unpolarized flying bird when viewed against a polarized sky. The detection of second-order motion in polarization is, to the best of our knowledge, the first demonstration of this ability in any animal. This discovery therefore opens a new dimension in our understanding of how animals use polarization vision for target detection and the broader importance of second-order motion detection for animal behavior. Fiddler crabs detect second-order motion in both intensity and polarization, a finding that expands our understanding of motion vision in animals and its role in predator detection and behavior. [ABSTRACT FROM AUTHOR]

A small number of pulsars are known to emit giant pulses (GPs), single pulses much brighter than average. Among these is PSR J0534+2200, also known as the Crab pulsar, a young pulsar with high GP rates. Long-term monitoring of the Crab pulsar presents an excellent opportunity to perform statistical studies of its GPs and the processes affecting them, potentially providing insight into the behavior of other neutron stars that emit bright single pulses. Here, we present an analysis of a set of 24,985 Crab GPs obtained from 88 hr of daily observations at a center frequency of 1.55 GHz by the 20 m telescope at the Green Bank Observatory, spread over 461 days. We study the effects of refractive scintillation at higher frequencies than previous studies and compare methods of correcting for this effect. We also search for deterministic patterns seen in other single-pulse sources, possible periodicities seen in several rotating radio transients and fast radio bursts, and clustering of GPs like that seen in the repeating fast radio burst FRB 121102. [ABSTRACT FROM AUTHOR]

Species recognition can be interpreted as the identification of sexual compatibility among individuals, which is related to the assessment of partner quality. This compatibility can be assessed using visual signals of conspecifics such as body coloration. Fiddler crabs constitute a group with a global distribution, comprising over 100 species with diverse colours. They perceive these body colours and use them for intersexual communication, primarily through signalling of the hypertrophied claw of males. However, few species have been investigated regarding the role of body coloration as a species-specific signal, and it remains unknown whether other body regions, such as the carapace, convey information about individual quality or species identity. Hence, this study aimed to examine whether carapace coloration of two sympatric fiddler crab species (Leptuca leptodactyla and Leptuca cumulanta) affects species recognition. To do this, we used individual females of L. leptodactyla that were subjected to a binomial choice of males with claws and carapaces reflecting different colours, simulating conspecifics (L. leptodactyla) or heterospecifics (L. cumulanta). We observed that females were unable to distinguish conspecifics from heterospecifics using only claw colour. On the other hand, we discovered that the white carapace coloration of L. leptodactyla was crucial for females to identify conspecific males. This is the first study to demonstrate that carapace coloration of male fiddler crabs functions in species recognition, reinforcing the idea that body traits beyond sexual ornaments can influence animal communication, affecting species identity and/or mate selection. • We examined whether Leptuca fiddler crabs use male body colour in species recognition. • Females chose males based solely on carapace colour. • Female L. laptodactyla chose L. cumulanta males with white painted carapaces. • Claw colour did not play a crucial role in interspecific recognition. [ABSTRACT FROM AUTHOR]

Based on a long-term dataset of species composition and infestation levels of associated organisms on the invasive Barents Sea red king crab, a multivariate analysis was conducted to determine the contributions of biotic and abiotic factors to the fouling community structure. Results indicate that host size and exoskeleton age were the most significant factors for diversity indices and infestation intensity. Abiotic factors played a lesser role in the formation of fouling communities. Temperature conditions during the mass molting periods were found to have significant effects, apparently acting as a trigger for the primary settlement of crab shells by benthic organisms. Our data not only provide new insights into the formation of fouling communities of decapod crustaceans, but also provide valuable information for further studies on the adaptation process of the red crab to the conditions of the Barents Sea. [ABSTRACT FROM AUTHOR]

Larval morphology in brachyuran crabs is an essential trait defining survival in the planktonic environment. The present study describes the morphology (carapace and chelipeds) of megalopa larvae in three different species (Percnon gibbesi, Cronius ruber , and Achelous hastatus) using geometric morphometric analysis (GMA). The study aim was to compare the observed body patterns at interspecific and intraspecific levels. The results showed a marked interspecific distinction of C. ruber larvae based on the rostral region of carapace and cheliped length. We relate these differences to advantages in life performance, as in other animal models, suggesting that larval morphology can be another factor contributing to the invasiveness of C. ruber. At intraspecific level, we found a high morphological similarity between two distant geographical locations, indicating strong genetic connectivity in the populations of P. gibbesi from the Canary Islands. Our findings advance the importance of larval morphology for species performance during the plankton phase that eventually can determine invasiveness in brachyuran crabs. We suggest future studies focusing on the inter-population comparisons of megalopa morphology at larger spatiotemporal scales. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are among the most important in the world and provide essential functions and services to humans. In this study, we examine the roles of environmental and historical factors in explaining contemporary patterns of species richness. We investigated spatial patterns of species richness of freshwater crabs by compiling geographic distribution maps for 1271 species. We employed six environmental variables slightly correlated and non-collinear to test environmental hypotheses. At a global scale, we identified three regions characterized by particularly high species richness: in northern South America (Neotropical biogeographic realm), in the Western Ghats and Sri Lanka (Oriental), and southwestern China (Oriental). The best-fitting model that explained global richness variation included environmental hypotheses: Temperature-Speciation, ResourceAvailability, HabitatHeterogeneity and AnthropicImpact. We also observed a historical influence on the pattern of richness, with distinct sets of environmental predictors of richness across taxa and biogeographic realms. Our models suggest that freshwater crab richness is associated with by varying processes occurring within specific environmental and historical scenarios. In general, we documented a concentration of freshwater crab richness in areas heavily impacted by human activities. These findings hold implications for the conservation of this taxonomic group. [ABSTRACT FROM AUTHOR]

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Context. To date, three pulsars have been firmly detected by imaging atmospheric Cherenkov telescopes (IACTs). Two of them reached the TeV energy range, challenging models of very high-energy (VHE) emission in pulsars. More precise observations are needed to better characterize pulsar emission at these energies. The LST-1 is the prototype of the large-sized telescopes, which will be part of the Cherenkov Telescope Array Observatory (CTAO). Its improved performance over previous IACTs makes it well suited for studying pulsars. Aims. In this work we study the Crab pulsar emission with the LST-1, improving upon and complementing the results from other telescopes. Crab pulsar observations can also be used to characterize the potential of the LST-1 to study other pulsars and detect new ones. Methods. We analyzed a total of ∼103 hours of gamma-ray observations of the Crab pulsar conducted with the LST-1 in the period from September 2020 to January 2023. The observations were carried out at zenith angles of less than 50 degrees. To characterize the Crab pulsar emission over a broader energy range, a new analysis of the Fermi/LAT data, including ∼14 years of observations, was also performed. Results. The Crab pulsar phaseogram, long-term light curve, and phase-resolved spectra are reconstructed with the LST-1 from 20 GeV to 450 GeV for the first peak and up to 700 GeV for the second peak The pulsed emission is detected with a significance level of 15.2σ. The two characteristic emission peaks of the Crab pulsar are clearly detected (> 10σ), as is the so-called bridge emission between them (5.7σ). We find that both peaks are described well by power laws, with spectral indices of ∼3.44 and ∼3.03, respectively. The joint analysis of Fermi/LAT and LST-1 data shows a good agreement between the two instruments in their overlapping energy range. The detailed results obtained from the first observations of the Crab pulsar with the LST-1 show the potential that CTAO will have to study this type of source. [ABSTRACT FROM AUTHOR]

A new genus and species within the family Xanthidae MacLeay, 1838, are described from coral reefs in the South China Sea. The new genus, Gothus, with its type species G. teemo sp. nov., is distinguishable from allied genera by characteristics of the carapace, chelipeds, and male pleon. Based on morphological evidence, we tentatively place this genus within the subfamily Euxanthinae Alcock, 1898. However, molecular systematic analysis based on COI , 12S , 16S, and H3 indicates that it does not form a stable monophyletic group with any related subfamily. Another species, Actaeodes consobrinus (A. Milne-Edwards, 1873), is also reclassified into this new genus, based on both morphological and molecular evidence. [ABSTRACT FROM AUTHOR]

Sahu, A.; Venkataramani, V.K.; Chandravanshi, S., and Chandran, S., 2024. Spatio-temporal distribution of portunid crabs within the Gulf of Mannar, southeast coast of India. Journal of Coastal Research, 40(5), 937–951. Charlotte (North Carolina), ISSN 0749-0208. To explore the variety of portunid crabs along the Gulf of Mannar coast, an intensive survey was conducted for 1 year from October 2021 to September 2022. The sampling was done biweekly, at four landing sites, i.e., Vedalai, Keelakarai, Therespuram, and Thiruchendur. The Gulf of Mannar has a rich diversity of portunid crabs, and bottom set gillnets are the primary method of capture. Twenty-seven species were recorded in the study area, representing five genera. The genus Charybdis recorded the highest number of species with 11 species, followed by the genus Portunus and the genus Thalamita with eight and four species, respectively. The genus Scylla and the genus Podophthalmus were represented by three and one species, respectively. To conduct the biodiversity assessment, the occurrence and abundance data of portunid crabs were collected for 12 months in all the selected landing centers in the Gulf of Mannar. The data collected were pooled together by month, station and season, which included summer (March-May); pre-monsoon (June-August); monsoon (September-November) and post- monsoon (December-February). From the collected occurrence and abundance data, 15 biodiversity indices were calculated using the PRIMER v7 computer software package. [ABSTRACT FROM AUTHOR]

As climate change transforms marine environments globally, species distributions correspondingly shift to locations where conditions have become or remain favourable. The ability to model these distributional shifts has been facilitated by species distribution models (SDMs). However, current SDM approaches have largely ignored climate‐driven changes in species interactions, which ultimately can have an important influence on species distributions. In this study, we utilize a long‐term, large‐scale dataset spanning 48 years and approximately 30 degrees latitude across the Canadian Atlantic shelf. We examine how climate influences the distribution and predation patterns of two invertebrates, northern shrimp Pandalus borealis and snow crab Chionoecetes opilio, aiming to evaluate the impacts of climate change on prey distributions. We found that both invertebrate species have a pronounced predicted response to climate change, with a northern shift in the distribution of northern shrimp and an overall reduction in abundance of both snow crab and shrimp associated with warming temperatures. Including predatory interactions as predictors in the SDMs (either directly via predator densities or via estimated predation rates) improved prediction accuracy for northern shrimp but not for snow crab. This is consistent with the ecology of these two species, as northern shrimp is more vulnerable to predation than snow crab. We found that the projections of future northern shrimp distributions are sensitive to the predicted spatial distribution and abundance of predators, highlighting the inherent complexity of predicting species response to climate change. Collectively, these results contribute to a broader literature that seeks to improve the capabilities of models to predict the effects of species interactions on species distributions under changing ecological conditions. [ABSTRACT FROM AUTHOR]

To evaluate the in vitro activity of ampicillin-sulbactam and cefoperazone-sulbactam against A. baumannii using the broth disk elution testing, a total of 150 A. baumannii isolates were collected from across China between January 2019 and January 2021, including 51 carbapenem-susceptible and 99 carbapenem-resistant isolates. Broth disk elution (BDE) and the broth microdilution (BMD) method were performed for all strains. The concentration range of the BDE was 10/10 µg/mL, 20/20 µg/mL, and 30/30 µg/mL for ampicillin-sulbactam, and 37.5/15 µg/mL, 75/30 µg/mL, 112.5/45 µg/mL, and 150/60 µg/mL for cefoperazone-sulbactam, respectively. Compared with BMD, the BDE results of ampicillin-sulbactam and cefoperazone-sulbactam showed a categorical agreement of 83.3% (125/150) and 95.3% (143/150), with minor errors of 16.7% (25/150) and 4.7% (7/150), respectively. No major error or very major errors were detected. The sensitivity differences by BDE of carbapenem-resistant A. baumannii (CRAb) to different concentrations of ampicillin-sulbactam showed statistically significant (p < 0.017), while those to cefoperazone-sulbactam at 37.5/15 µg/mL, 75/30 µg/mL, and 112.5/45 µg/mL were significant (p < 0.008). However, no significant difference in sensitivity was observed between 112.5/45 µg/mL and 150/60 µg/mL (p > 0.008). In conclusion, the BDE is a reliable and convenient method to detect the in vitro activity of cefoperazone-sulbactam against A. baumannii, and the results could serve as a clinical reference value when deciding whether or not to use high-dose sulbactam for the treatment of A. baumannii infections. [ABSTRACT FROM AUTHOR]

Fiddler crabs have been used as model organisms in many laboratory and field studies. In their natural environment, social interaction with other fiddler crabs (conspecific or heterospecific) is recurrent, but manipulative studies involving these crabs as models are often performed with isolated individuals. The isolation of an animal can interfere in the behaviors recorded as response variables. Thus, the aim of this study was to evaluate whether the presence of other individuals affects the performance of behaviors of fiddler crabs Leptuca uruguayensis. We tested two hypotheses in the field: (1) the visual stimulus of the crab assemblage affects the activity of male fiddler crabs; and (2) the presence of other conspecific affects the activity of male fiddler crabs depending on the sexes of the individuals present. We found the activities of L. uruguayensis males mediated by social interactions does not depend exclusively on visual stimuli. Physical interaction with other conspecifics of both sexes enables the perception of stimuli which can influence the waving behavior of L. uruguayensis males. We suggest that behavioral studies with this model should consider the presence of other individuals. Understanding the behavioral complexity of a model organism contributes to more robust experiments with greater control of interfering variables. [ABSTRACT FROM AUTHOR]

One of the Brachyura crabs found in the lower reaches of the Serayu River is Varuna litterata, also known as the "herring bow crab". This crab usually inhabits shallow tidal areas and hides under rocks, logs, or dead leaves. It is a highly adapted crab found in a wide range of salinities. V. litterata is also a fishery product consumed in Thailand, the Philippines, and Indonesia. This research was conducted in the Lower Serayu River, Central Java, which consists of three observation stations, namely: 1) the first station is located above the dam with fresh water, 2) the second station is below the dam with fresh water properties and 3) the third station is downstream (estuary) of the Serayu River with brackish water. This research was conducted for four months, from October 2023 to January 2024. This study aimed to determine the level of egg development in V. litterata. The results showed that V. litterata experienced four stages in egg development and then hatched into zoea. At the initial development stage, V. litterata eggs will be purple; in the second stage, the eggs will turn reddish; in the third development stage, the eggs will turn orange to brownish; and in the fourth stage, the eggs will develop and become black. V. litterata that will spawn will migrate to brackish waters to hatch their eggs. V. litterata produces 20,708 - 85,886 eggs with an average egg diameter of 0.440 - 0.466 mm. [ABSTRACT FROM AUTHOR]

This study reports the presence of Percnon gibbesi in the North Adriatic Sea, specifically at Cape Kamenjak, Croatia. The species was first observed in the Mediterranean in 1999, and has rapidly proliferated across the region, with Cape Kamenjak now representing its northernmost finding. Seven individuals were identified during free-diving activities in Pinižule Bay in December 2023. Follow-up surveys in January 2024 revealed their presence approximately 15 meters from the shore, under large boulders, at depths ranging from 2.6 to 3.6 meters, with water temperatures ranging from 13 to 15 °C. Morphological examinations confirmed the specimen as male P. gibbesi, with a carapace length of 15 mm, carapace width of 14.3 mm, and a weight of 1.87 g. Shipping was identified as a primary vector of introduction due to the proximity of Cape Kamenjak to major Mediterranean ports. This research provides insights into the invasion dynamics of P. gibbesi in the northern Adriatic, urging proactive management strategies and collaborative efforts in monitoring programs. [ABSTRACT FROM AUTHOR]

The degree of deacetylation, DDA is the most important characteristic for a specific chitosan sample as it mainly influences its chemical and biological properties. Several natural wastes may be used as sources for chitin as for example crabs' and shrimps' exoskeletons, and the yield of chitosan extraction is generally small and depends on the chitin extraction and the deacetylation step. The simultaneous maximization of yield and deacetylation degree DDA pointed out some optimal operating conditions of the deacetylation procedure. The maximum yield and maximum DDA can be obtained working with higher NaOH concentrations and longer duration of this step. [ABSTRACT FROM AUTHOR]

Freshwater crabs (Potamiscus manipuriensis), commonly consumed as local delicacies by the native people in the state of Manipur, were found to harbour metacercariae of Microphallus sp. (Family Microphyllidae), which were morphologically different from metacercariae of Microphallus spp reported earlier from different regions. So, PCR-based molecular characterization of this metacercaria was done utilizing rDNA marker regions: larger subunit (LSU) or 28S (D1-D3 region) and inter-transcribed spacer 2 (ITS2). Sequence and phylogenetic analyses confirmed that the taxon under study belonged to family Microphyllidae of genus Microphallus. [ABSTRACT FROM AUTHOR]

Nepinnotheres villosulus (Guérin-Méneville, 1832) [ Guérin-Méneville, 1829–1837 ] [type locality: Timor] and Nepinnotheres edwardsi (De Man, 1887) [type locality: Mergui Archipelago], as currently understood, are both reportedly widespread in Southeast Asia and northern Australia, and unique in the genus in having females densely covered by a setal tomentum that completely obscures the surfaces of the carapace and pereiopods. Based on the limited information contained in the type accounts, N. edwardsi and N. villosulus appear indistinguishable, but this cannot currently be confirmed by comparing type material because the holotype of N. villosulus , the senior name, is lost. A neotype is therefore designated for N. villosulus to fix its identity and taxonomic status as a senior synonym of N. edwardsi. In addition to the unique setation pattern of female N. villosulus , males of the species also present important differences from those of male Nepinnotheres sensu stricto. Pinnotheres trichopus Tesch, 1918 [type locality: Elat, Great Kei Island, Indonesia], is also shown to be a junior synonym of P. villosulus. Moreover, recent molecular phylogenetic analyses determined that N. villosulus is phylogenetically distant from Nepinnotheres sensu stricto. As such, we establish a new genus for N. villosulus. [ABSTRACT FROM AUTHOR]

The corystid Gomeza serrata Dana, 1852, described from Patagonia in South America has rarely been reported and its taxonomy is poorly understood. While superficially similar to G. bicornis Gray, 1831 from the Indo-West Pacific and the type species of Gomeza Gray, 1931, direct comparisons have not been recorded. Examination of topotypic specimens show that Gomeza serrata is actually a juvenile of Peltarion spinosulus (White, 1843), a member of the family Trichopeltariidae. A neotype is selected for G. serrata to stabilize its taxonomy. [ABSTRACT FROM AUTHOR]

Decapod crustaceans and their associated fisheries are an important resource globally, and demand for seafood continues to grow alongside a growing human population. With a combined 2023 value of €36 million in Ireland, three species of brachyuran crabs, the velvet crab (Necora puber Linnaeus, 1767), edible crab (Cancer pagurus Linnaeus, 1758), spider crab (Maja squinado Herbst, 1788)), and the European lobster (Homarus gammarus Linnaeus, 1758) are decapods of commercial importance. These species are also important components of their respective ecosystems. Parasite infection can affect the health of crustaceans and may affect population productivity. Microparasites, including paramyxids (Hematodinium spp.) and microsporidians can infect decapod crustaceans and have a range of effects on their hosts. We assessed three microparasites in four crustacean species. Paramarteilia canceri was found in all three crab species, and we provide the first genetic confirmation in spider crabs. A microsporidian associated with cotton crab disease, Ameson sp. was identified in N. puber , along with a second species of microsporidian which will require further classification. None of the three parasite groups were identified in Homarus gammarus. Species of Hematodinium were not identified in any of the species studies. Our work highlights the need for parasite surveys to uncover parasite diversity and prevalence in crustaceans to help elucidate host-parasite interactions, and the potential impacts of parasites. [ABSTRACT FROM AUTHOR]

The sex-specific differences in the growth and population characteristics of the high-commercial-value sand crab Ovalipes punctatus were investigated in Korea. The estimated allometric growth between the sexes showed significant differences in all morphometric measurements. In the classification of growth types, carapace width-chela length exhibited positive and negative allometric growth in males and females, respectively. Carapace width-abdominal width showed positive relative growth in both sexes, and orbital spine width exhibited negative relative growth in both sexes. Consequently, sexual dimorphism was evident in all measured traits. Growth parameters estimated using the ELEFAN function of the FiSAT II program indicated higher values in males compared to females. Asymptotic length (CW∞) for males was estimated at 139.2 mm, whereas for females it was 116.6 mm. Additionally, the growth coefficient (K) was higher in males (0.65) than in females (0.54), suggesting faster growth in males. The winter point (WP) was 1 for males and 0.7 for females, indicating slower growth in males during the colder December and slower growth in females during the spawning period in August. The modified von Bertalanffy growth curves indicated asymptotic growth in all sexes, and the growth performance index (φ') showed higher values in males (4.10) compared to females (3.87), reflecting differences in growth curves. The steady increase in recruitment rates from July to September was associated with the appearance of larvae and their subsequent growth into juveniles, leading to their recruitment into the population during this period. Therefore, O. punctatus exhibited sex-specific differences in growth parameters, suggesting distinct growth strategies between the sexes. [ABSTRACT FROM AUTHOR]

The present study examined the genetic diversity of two populations of Dotilla myctiroides (Milne-Edwards) from Peninsular Malaysia. Based on 640-bp COX1 (cytochrome c oxidase subunit 1) gene sequences, the D. myctiroides specimens from Peninsular Malaysia, Singapore and India formed a lineage which was distinctly separated from Dotilla wichmanni and D. fenestrata. Sixteen COX1 haplotypes were found in Peninsular Malaysia samples, with 11 haplotypes in the Morib sample, eight in the Tanjung Tuan sample, and three common haplotypes in these samples. The Singapore specimen had the commonest haplotype of Peninsular Malaysia, while the Indian specimen had a distinct haplotype. The proportions of the two most common COX1 haplotypes were not significantly different between the Morib and Tanjung Tuan samples. The difference in the mean haplotype diversity between these samples was statistically significant. However, the nucleotide diversity of the two samples was not significantly different and there was no genetic subdivision/differentiation between the two populations. The high number of closely related haplotypes indicates the possibility of a recent population expansion. The data provide valuable information for future studies on the genetic diversity, population structure and phylogeography of Dotilla species. [ABSTRACT FROM AUTHOR]

Geosesarma shows intraspecific carapace color variation, which might lead to species misidentification. The problem can be solved using DNA barcoding. There is one research about Geoserarma from the southern slopes of Mount Slamet, but samples were only collected from the Banjaran River for morphological identification. Here, we collected samples from wider areas covering south slope and applied molecular identification. This research aims to assess Geosesarma diversity in south-slope Mount Slamet Central Java, Indonesia based on the cytochrome c oxidase 1 gene barcoding. Surveys were carried out at six sites. Taxonomic identification was done using the barcoding technique. Four morphotypes were obtained during the research. Three morphotypes with the square carapace were identified as Geosesarma, while the remaining one morphotype was included in Parathelphusa. The three Geosesarma morphotypes were barcoded as Geosersarma dennerle because their genetic identity was more than 97% of the G. dennerle sequence in Boldsystems. In contrast, the Parathelphusa morphotype was barcoded as P. convexa with a genetic identity of 97.50%. It can be concluded that the Geosesarma crab on the south-slope Mount Slamet only consists of one species but has carapace and claw color variations. The data are essential for Geosesarma market development and conservation in the region. [ABSTRACT FROM AUTHOR]

The detection technology of soft-shell crab breaks the traditional soft-shell crab breeding method. Conventional farming practices rely heavily on human labor for the identification of soft-shell crab birth, and manual inspections are prone to issues such as delayed and inaccurate results. In this paper, we propose an improved high-precision detection algorithm called YOLOF based on YOLOv5. This algorithm achieves precise detection of soft-shell crab. To address the absence of soft-shell crab detection datasets on the internet, this paper establishes the Crab Molting Detection Dataset (CMP) for the purpose of training neural networks. The detection algorithm has undergone several improvements in the following aspects: the introduction of the FassterNetT1 feature extraction network to replace the original CSPDarknet53 backbone network significantly reduces model complexity and computational overhead; The incorporation of an additional auxiliary prediction feature layer of size 5 × 5 enhances the model's adaptability for detecting various molting states of crabs; the activation function GeLU was introduced, to enable the model to extract features more smoothly and reduce information loss during feature extraction; additionally, the definition of Mixed Convolution (MConv) was proposed to replace Partial Convolution (PConv) in the FasterNet Block. MConv exhibits comparable speed to PConv while possessing high-performance convolution capabilities, allowing the backbone network to extract more abundant semantic information; The introduction of the Content-Aware ReAssembly of FEatures (CARAFE) operator, a universal upsampling algorithm, enhances the extraction of crab shell contour information, thereby improving the model's accuracy in detecting soft-shell crab; addition of an Explicit Visual Center (EVC) in the network neck to strengthen the model's grasp of long-range dependencies and critical information in the image, enhancing the model's robustness. The experimental results demonstrate that YOLOF achieves a 5.4% improvement in mean average precision compared to the original YOLOv5s algorithm. The average precision for the classes "shedding_crab" and "end_unshell" increased by 1.7% and 16.3% respectively. The model running speed is 28FPS, indicating that the proposed YOLOF algorithm can accurately and efficiently identify the molting states of crabs. This study provides the theoretical foundation and technical support for the realization of an automated system for soft-shell crab cultivation. [ABSTRACT FROM AUTHOR]

Species experience a variety of environmental and anthropogenic conditions across their ranges leading to spatial variation in population dynamics. Understanding population dynamics under different conditions is important but it is challenging to allocate limited effort to spatial and temporal subpopulation monitoring. Using GLMMs, we analyze survey data of a metapopulation of coconut crabs spanning 7 years and 15 sites in and near the Pemba archipelago, Zanzibar, to estimate trends in population size (based on catch per unit effort), weight and sex ratio at the meta‐ and subpopulation level and investigate anthropogenic drivers of these trends. We found that the overall metapopulation has remained stable in terms of size and composition over the survey period, but observed diverging trends in population size and sex ratio at some subpopulations. Formal protection of sites was associated with positive population trends. Of nine sites for which we could estimate site‐specific trends, three showed increasing and two decreasing trends, whereas four sites had stable subpopulations. Although anthropogenic factors affected the average weight, and the incidence of small and large individuals, we found no temporal trends in any weight‐related measures. Furthermore, there were no apparent patterns between weight‐related measures and subpopulation trends. The metapopulation was biased toward males, and exploitation appeared to be associated with declining trends in the proportion of females, likely an artifact of a strong decline in the proportion of females in one of only two exploited sites in the dataset. Educational campaigns implemented in 2020 at six sites were not related to higher population sizes in later surveys. The variable trends in subpopulation sizes and composition highlight the need for spatially replicated monitoring in metapopulations. The analyses further provide a detailed baseline for future subpopulation studies of this vulnerable species in one of its last remaining metapopulations in the Western Indian Ocean. [ABSTRACT FROM AUTHOR]

In order to gain better understanding of the Neanderthals' subsistence exploitation of marine crustaceans, this work presents evidence on the consumption of brown crabs using experimentation following-up from the archaeological evidence recovered from the 2010-2013 excavation of Gruta da Figueira Brava (Portugal). Amongst the aquatic fauna from occupation phase FB4, which dates to MIS-5b, brown crabs (Cancer pagurus) are numerous. The average carapace width estimated from their remains is 16 cm, and skeletal part analysis reveals the introduction of complete animals and their on-site processing. Due to the lack of a referential corpus for the interpretation of archaeological crab taphonomy, we experimented with the processing of two raw, two boiled, and two roasted brown crabs. We found that manual processing of large adult Cancer pagurus is only possible for the disarticulation of the walking legs, and the separation of the claws. Experimental results indicate that archaeological crabs were roasted, which weakened the shell and facilitated breaking it open. Though it is also possible to manually disarticulate the fingers, most times it requires a small hammerstone. Impact scars and longitudinal fractures bear witness to the use of such tools to access the meatier parts of both the propodus and the dactylopodus. [ABSTRACT FROM AUTHOR]

The article presents a comparative analysis of the fecundity of the Barents Sea red king crab, its size composition, and size at 50% maturity during the period of its expansion and acclimatization and at present during intense fishing. In addition, based on the published literature data, differences are estimated between the above parameters of Barents Sea individuals and individuals from the crab's natural habitat. In 2019–2022, the Barents Sea red king crab showed a trend of decreasing its fecundity compared to the period of active acclimatization (1995–2003) before commercial exploitation started. In recent years, changes in the reproductive parameters of the Barents Sea red king crab population have increased the similarity of these characteristics to those for native populations from the Pacific region that began to be actively exploited in the early 20th century. [ABSTRACT FROM AUTHOR]

The article presents analyses of the dynamics of injuries of the snow crab opilio in catches taken during surveys in 2008–2022, as well as data collected by observers in the fishery for this species in the Russian part of the Barents Sea in 2014–2022. The average proportion of injured crabs in catches taken during research surveys increased from 5–11% in 2008–2010 to 45% in 2022. The increase in the number of injured individuals in catches is higher for large males. The modeling results showed that the increased proportion of injured individuals in the period preceding commercial exploitation is associated with an increase in intrapopulation interactions, while during active commercial exploitation, it is associated with fishing pressure on the population, when some individuals, including crabs injured during capture, are returned to the sea after processing. [ABSTRACT FROM AUTHOR]

The present work provides an updated and corrected list of hosts for the five European species of pinnotherid crabs, taking into consideration all recent published works as well as new data obtained in the present study. In relation to the number of hosts, there are two groups of species, one composed by Pinnotheres pisum and Afropinnotheres monodi with the highest number of hosts, and a second group, with a reduced number of hosts and more specific taxa, consisting of three other species: Nepinnotheres pinnotheres, Pinnotheres bicristatus, and P. pectunculi. When studying the relationships between host preferences, host distributions, and pea crab distributions, we could not find a clear direct relationship between these parameters. Temperature is also probably an important influence and relevant factor responsible for the distribution of pinnotherid crabs, and this may be independent from the potential distribution due to the distribution of hosts. [ABSTRACT FROM AUTHOR]

Crabs are fundamental in coastal ecosystems due to their role in nutrient cycling, habitat structuring, population control and as indicators of environmental health. Investigating the size distribution and life stages of these species is crucial for understanding their ecology and designing effective conservation strategies. This study provides data on the distribution and stage ratios of two populations of local species of the genus Cyrtograpsus (Decapoda: Brachyura: Varunidae) in the Playa Cangrejales intertidal. These endemic species had not been previously described in the study area, highlighting the need for further research in the future. Three surveys were conducted from December 2019 to February 2020, following a transect perpendicular to the coast, obtaining two series of data (C‐I and C‐II). Specimens were identified, sexed and measured in situ for subsequent release. A total of 1099 individuals were counted, identifying Cyrtograpsus affinis (C‐I = 278; C‐II = 332) and Cyrtograpsus angulatus (C‐I = 215; C‐II = 277), with a higher proportion of C. affinis. The presence of these species at Playa Cangrejales coincides with the geographical distribution reported in the literature, although the proportions differ from those reported for other Argentinean beaches. The most frequent lengths were equal to or less than 10 mm cephalothorax length (±1 mm). The maximum lengths reported in the literature for each species were not recorded. For C. angulatus, juveniles always predominated over adults and recruits. C. affinis showed fluctuations between adult and juvenile proportions in the upper and middle zones, with adults predominating in the lower zone during December and February. Juveniles occupied all mesolittoral floors, whereas adults were more frequent in the middle and lower floors. This information is essential to develop management tools to protect these species and their environment. The division between stages was realized following criteria from the literature. Analyses and interpretations were made using data distribution and frequency graphs. [ABSTRACT FROM AUTHOR]

Freshwater crabs play essential roles in the well-functioning of the inland aquatic ecosystems. However, due to the lack of sufficient molecular resources, the study of freshwater crabs has been greatly hindered. In this study, the mitochondrial genome of Huananpotamon koatenense, a freshwater crab endemic to China, was sequenced for the first time. This mitogenome sequence is 15,528 bp long, and contains 13 protein-coding genes, 2 rRNA genes and 22 tRNA genes. Phylogenetic analyses based on 25 mitogenomes showed that H. koatenense was clustered with the known congeneric species of H. lichuanense. [ABSTRACT FROM AUTHOR]

Symbiosis is one of the most important evolutionary processes shaping biodiversity. Phylogenetic and morphological analyses can enhance our understanding of the origin and evolution of symbiosis. The symbiotic relationship between Trapezioidea crabs and branching corals, with high species diversity and flexible symbiosis, is iconic coral/crustacea symbiosis in the marine ecosystem. In this study, the evolutionary history of Trapezioidea crabs was investigated by constructing a phylogenetic relationship based on the whole mitogenome sequences of 66 Brachyura species, including 17 newly sequenced Trapezioidea species. Trapezioidea crabs were split at least into two phylogenetically distant lineages originated at different times. The two lineages, both including facultative and obligate symbionts, convergently evolved smooth and flattened trapezoidal carapaces favorable for specific coral-living. The significantly larger cheliped in obligate species indicated a deeper degree of coral dependence compared with facultative and other associate species. [ABSTRACT FROM AUTHOR]

We established a mathematical model for predicting the health status of Chinese mitten crab based on deep inference model (YOLO-v7). Firstly, crabs grew in the natural environment form the back pattern characteristics, which could be divided into six features of lateral teeth, keel ridge, frontal gibbosity, verruca process, neck groove, compound eye according to morphometrics. Based on the human visual attention mechanism, the effective feature characterizations were visualized with higher classification accuracy in the YOLO-v7 model. Moreover, according to the calculation results, the image labeling software-Labellmg was used to mark the vitality grade of the first five different feature combination modes, respectively. Then, the YOLO-v7 model was used to train and reason the marked data, and the optimal Chinese mitten crab freshness identification model was obtained. The experimental results showed that the proposed texture feature combination algorithm of verruca process + cervical groove could basically realize the recognition of the health status of Chinese mitten crab. The overall training accuracy could reach 95%, the reasoning accuracy could reach 96.20%. Moreover, the reasoning time of each vitality grade of Chinese mitten crab was less than one second. This method had great application prospect and market value, which provided key technology for developing nondestructive testing equipment for large-scale online quality of Chinese mitten crab. [ABSTRACT FROM AUTHOR]

Simple Summary: Simple Summary: We developed R-TNET, a detection model tailored to identify one-year-old sexually precocious crabs. By addressing issues like subtle classification features and overlapping masks, the model was able to accurately identify and localize juvenile crabs on the validation data, and the mean average precision reached 88.78%. This effect meets practical needs and can be applied in the field of intelligent sorting, thus improving non-destructive technology in aquaculture. The cultivation of the Chinese mitten crab (Eriocheir sinensis) is an important component of China's aquaculture industry and also a field of concern worldwide. It focuses on the selection of high-quality, disease-free juvenile crabs. However, the early maturity rate of more than 18.2% and the mortality rate of more than 60% make it difficult to select suitable juveniles for adult culture. The juveniles exhibit subtle distinguishing features, and the methods for differentiating between sexes vary significantly; without training from professional breeders, it is challenging for laypersons to identify and select the appropriate juveniles. Therefore, we propose a task-aligned detection algorithm for identifying one-year-old precocious Chinese mitten crabs, named R-TNET. Initially, the required images were obtained by capturing key frames, and then they were annotated and preprocessed by professionals to build a training dataset. Subsequently, the ResNeXt network was selected as the backbone feature extraction network, with Convolutional Block Attention Modules (CBAMs) and a Deformable Convolution Network (DCN) embedded in its residual blocks to enhance its capability to extract complex features. Adaptive spatial feature fusion (ASFF) was then integrated into the feature fusion network to preserve the detailed features of small targets such as one-year-old precocious Chinese mitten crab juveniles. Finally, based on the detection head proposed by task-aligned one-stage object detection, the parameters of its anchor alignment metric were adjusted to detect, locate, and classify the crab juveniles. The experimental results showed that this method achieves a mean average precision (mAP) of 88.78% and an F1-score of 97.89%. This exceeded the best-performing mainstream object detection algorithm, YOLOv7, by 4.17% in mAP and 1.77% in the F1-score. Ultimately, in practical application scenarios, the algorithm effectively identified one-year-old precocious Chinese mitten crabs, providing technical support for the automated selection of high-quality crab juveniles in the cultivation process, thereby promoting the rapid development of aquaculture and agricultural intelligence in China. [ABSTRACT FROM AUTHOR]

Sympatric mud crab species Panopeus americanus and Panopeus austrobesus are found in intertidal environments associated with muddy and rocky habitats in the Western Atlantic coast. Therefore, they are a suitable model system to be used in studies focused on investigating biological coexistence aspects between close species, such as population structure and habitat. The aims of the current study are to describe and compare the distribution of two sympatric mud crab species -- P. americanus and P. austrobesus -- based on their spatial and temporal distribution, in a low human impact estuarine complex area. The hypothesis that these two species show similar distribution, although one species is more abundant than the other, was herein tested. Sampling was carried out in the intertidal zone of a specific area in Cananeia estuarine complex, São Paulo State, Southeastern Brazil, in different periods of time for two years. Both species presented similar pattern distribution and frequency, with predominance in the middle and high intertidal zones, including all demographic categories. However, Panopeus americanus was more abundant and presented smaller mean size in all sampling zones. The pronounced disparity in size between the species suggests divergent dietary preferences, potentially related to prey size allowing the coexistence of these sympatric and syntopic species. The predominance of these two species in the upper intertidal zones was understood as a strategy for avoiding competition with the intertidal alpheid shrimps. [ABSTRACT FROM AUTHOR]

Limitations on energetic resources create evolutionary trade-offs, prompting us to investigate if investment in claw strength remains consistent across crustaceans living in diverse habitats. Decapod crustaceans living in deep-sea hydrothermal vents are ideal for this study due to their extreme environment. In this study, we investigated whether decapods (blind crab Austinograea sp. and the squat lobster Munidopsis lauensis) living in deep-sea hydrothermal vents prioritize investing in strong claws compared to the carapace, like coastal decapods. We analyzed exoskeleton morphology, mechanical properties, structures, and elemental composition in both the carapace and claws of four Decapoda species (two each from Brachyura and Anomura infraorders) in vent and coastal habitats. Coastal decapods had ∼4–9 times more teeth on their claw cutting edge than the vent species. Further, only the coastal species exhibited higher firmness in their claws than in their carapaces. Each infraorder controlled exoskeletal hardness differently: Brachyura changed the stacking height of the Bouligand structure, while Anomura regulated magnesium content in the exoskeleton. The vent decapods may prioritize strengthening their carapace over developing robust claws, allocating resources to adapt to the harsh conditions of deep-sea hydrothermal vents. This choice might enhance their survival in the extreme environment, where carapace strength is crucial for protecting internal organs from environmental factors, rather than relying on the powerful claws seen in coastal decapods for a competitive advantage. [ABSTRACT FROM AUTHOR]

Fishing behavior is an important link between management decisions and bioeconomic outcomes. The diversity in fishers' behavior, motivations, and abilities should inform incentive structures if management aims to consider heterogeneous impacts on and by communities. Modeling human behavior in resource management is important for successful fisheries, especially for fisheries undergoing rapid transformation, such as the Alaskan snow crab fishery. This study modeled how snow crabbers choose where to fish in the eastern Bering Sea and examined the diversity of strategies among individuals by fitting a random utility model to data on fishing locations using a variety of potential drivers of behavior as covariates. The overall fishing strategy of the snow crab fleet prioritizes revenue and shared information, while avoiding risk, poor weather, and cost. Diversity of fishing strategies was driven by differences in spatial footprint, vessel size, and ports of landing. Larger vessels ventured farther north, where weather conditions are more extreme. Despite differences in vessel size, crabbers were spatially adaptive and switched fishing regions depending on the abundance and distribution of crab. These findings on the patterns of fishing strategies can inform better management of the Alaskan snow crab fishery as it undergoes rebuilding. [ABSTRACT FROM AUTHOR]

In Indonesia, the sand crab Albunea symmysta distribution includes Java, Sumatra, and Moluccas. Populations are assumed to be differentiated between western and eastern Indonesia due to the Wallace line; however, no information on the genetic diversity and differentiation of A symmysta in Indonesia is available. This study was conducted to clarify the genetic diversity and differentiation of A. symmysta in Indonesia. During the sampling campaign, A. symmysta specimens were found only in Java and Papua. Genetic analysis based on the 643-bp fragment of the partial COI gene from 32 individuals revealed significant genetic differentiation between the Java and Papua populations (FST = 0.94, p < 0.005). The haplotype connectivity of the five A. symmysta sampling sites revealed a two-clade network. Based on analysis of molecular variance, most of the variation was found among populations (94.21%) rather than within populations (5.79%). Tajima's D and Fu's FS values indicated a population expansion. Overall, the findings support a high level of differentiation between the Java and Papua A. symmysta populations, suggesting the separation of population stocks due to low connectivity. [ABSTRACT FROM AUTHOR]

This study examined heavy metals in some aquatic organisms [crabs (Callinectes amnicola), periwinkles (Tympanotonus fuscatus) and oysters (Crassostrea gasar)] from Eyaa Creek, Onne, in southern Nigeria. Samples were collected from four stations monthly for three months. Characterization of the environment was via physico-chemical properties, while heavy metal analysis was by Atomic Absorption Spectrometry. Physico-chemistry results indicated: temperature; 30.2 - 30.7oC; pH: 6.7 - 6.8; dissolved oxygen: 6.1 - 6.3 mg/l; electrical conductivity: 18.8 - 20. 8 mS/cm; total dissolved solids: 4698.5 - 6212.0 mg/l; salinity: 11.1 - 12.4 PSU and turbidity: 3.7 - 4.7 NTU. ANOVA showed insignificant difference (p>0.05) between stations indicating homogeneity of the area assessed. Mean metal concentrations (mg/kg) in the organisms were cadmium: 0.18 ± 0.09 - 0.60 ± 0.08; chromium: 0.41 ± 0.14 - 0.78 ± 0.08; iron: 12.1 ± 6.9 - 20.2 ± 7.7; lead: 0.31 ± 0.2 - 0.91 ± 0.05. Chromium and lead values were above permissible values of FAO/WHO and EU but cadmium fell within and above the limits. Principal component analysis did not show a clear pattern with organisms' feeding habit but discriminated based on metal concentrations. In conclusion metal concentration in periwinkles>crabs>oysters which was related to their feeding habits in terms of sediment and pelagic affiliations. [ABSTRACT FROM AUTHOR]