Distribution Of Crabs Research Articles

Redox and metabolic strategies developed by anterior and posterior gills of the crab Neohelice granulata after short periods of hypo- or hyper-osmotic stress

The aim of this study was to identify the response pattern of redox balance, Na+/K+ATPase activity and HSP70 expression in the posterior and anterior gills of the crab Neohelice granulata submitted to hypo- or hyper-osmotic stress for 1 h and 6 h. After 1 h of either type of osmotic stress, there was an increase in catalase activity, but a decrease in GSSG/GSH ratio (oxidized to reduced glutathione ratio) and Na+/K+ATPase activity in both gill sets. H2O2 levels decreased only in the posterior gills. H2O2 levels and Na+/K+ATPase activity remained reduced after 6 h of exposure to either type of osmotic stress in both gill sets. The GSSG/GSH ratio returned to initial levels after 6 h of hyper-osmotic stress, whereas it increased 10 times in both gill sets after hypo-osmotic stress. Furthermore, HSP70 protein expression increased in posterior gills after 6 h of hypo-osmotic stress. H2O2 levels in tank water decreased after hypo-osmotic challenge and increased after 6 h of hyper-osmotic stress, indicating increased H2O2 excretion. Therefore, N. granulata gills have redox, metabolic and molecular strategies to deal with rapid osmotic challenges, an important environmental parameter that influences juvenile and adult crab distribution and abundance within different populations.

Diversity and distribution of Dorippid Crabs (Brachyura: Dorippidae) in East Coast of Lampung, Indonesia

Dorippid crabs (Brachyura: Dorippidae) commonly live in sand or mud substrate at shallow coastal water. These crabs are a macro-benthos, mostly found in tropic, have no economic value, but have high abundance in blue swimming crab habitat and lack information in Indonesia. This study aims to determine diversity and species distribution of dorippid crabs in East Coast of Lampung, Indonesia. This study was conducted on March-April 2017 in seven locations along coastal area (i.e. Labuhan Maringgai, Kuala Penet, Sekopong, Wako, Seputih, Sungai Burung, and Kuala Teladas). The specimen was collected from the blue swimming crab gill-net fishery as by-catch. Each location found by this family was noted at coordinate point at satellite imagery map and processed using ArcGIS. Two species have been found, there are Dorippe quadridens and Dorippoides facchino. Both species were found at every location, except D. quadridens at Sungai Burung as well as D. facchino in Sekopong. There are 74% among the sample of fishermen caught D. quadridens in those areas with an average number of 36 individuals and weight of 959 grams. While, 40% of fishermen caught D. facchino with an average number of 17 individuals and weight 152 grams.

Does the wild-caught Chinese mitten crab megalopae perform better than the hatchery-produced seed during the juvenile culture?

Although wild Yangtze Eriocheir sinensis juveniles (coin‐sized seed) have better culture performance than the pond‐reared juveniles during the adult crab culture stage, the culture performance of wild‐caught megalopae (WC) remains unknown. Therefore, this study was designed to compare the growth, survival rate, crab yield, feed conversion rate (FCR), precocity, final weight and size distribution between WC and hatchery‐produced megalopae (HP) during the juvenile culture stage. Wild‐caught megalopae had significantly higher body weight, weight gain rate (WGR) and specific growth rate (SGR) during 0–4 weeks but lower WGR and SGR than HP during 4–8 weeks (p < .05). Although WC had a significantly lower survival rate and yield of normal juvenile crabs than HP, total yields of normal juveniles and precocious crabs were similar. Wild‐caught megalopae had a significantly higher precocious rate and yield of precocious crabs than HP (p < .05). Regardless of sex, no significant differences were found in the gonadosomatic index (GSI), hepatosomatic index (HSI) and final weight of normal juveniles and precocious crabs between WC and HP. As for the size distribution of normal crabs, WC had a higher percentage of small female juveniles (<3 g) but a lower proportion of middle size ranges (3–5.99 g and 6–8.99 g) than HP for females (p < .05), and there was no significant difference for males. In conclusion, wild megalopae of the Yangtze E. sinensis had worse culture performance than the hatchery‐produced seeds; therefore, wild megalopae would not be recommended for commercially juvenile culture of E. sinensis.

Distribution and Habitat Use of the InvasiveCarcinus maenasL. (European Green Crab) and the NativeCancer irroratus(Say) (Rock Crab) in Intertidal Zones in the Upper Bay of Fundy, Canada

Carcinus maenas (European Green Crab) is an invasive marine portunid crab that has established populations globally outside of its native range and has been implicated in declines of benthic invertebrates in invaded ecosystems. Observations of Green Crab on intertidal mudflats in the upper Bay of Fundy have increased in recent years. We assessed the distribution and relative abundance of crab populations in Chignecto Bay, an arm of the upper Bay of Fundy, by trapping Green Crab and native Cancer irroratus (Say) (Rock Crab) at mudflats and in rocky intertidal zones in 2013 and 2014. Spatial distribution of Green Crabs indicated a preference for rocky intertidal habitats and greater abundance geographically lower in the Bay, which would correspond with an initial introduction at the mouth of the Bay and subsequent inward expansion. Abundance declined drastically from 2013 to 2014, suggesting that Green Crab may not yet be well established in Chignecto Bay. Carapace width indicated that crab age may be less variable further into the Bay, suggesting these sites may only be colonized in years with favorable environmental conditions. The population may be vulnerable under poorer conditions in other years, like 2014, when high overwintering mortality is a possible cause for the observed decline. There was not a corresponding decline in native Rock Crab. While Green Crab abundance is currently relatively low in Chignecto Bay, and their impact on mudflats likely minimal, prolonged favorable environmental conditions could lead to an increased presence.

Interference competition as a key determinant for spatial distribution of mangrove crabs

BackgroundThe spatial distribution of mangrove crabs has been commonly associated with tree zonation and abiotic factors such as ground temperature and soil granulometry. Conversely, no studies were designed to investigate the role of competition for resources and predation in shaping crab distribution in mangroves, despite these biotic factors are recognised as key determinants for spatial patterns observed in the communities colonising rocky and sandy intertidal habitats.We studied floral and faunal assemblages in two zones of a Sri Lankan mangrove, a man-made upper intertidal level and a natural eulittoral, mid-shore one. Leaf choice experiments were designed to study both feeding rate and intra and inter-specific interactions for food of sesarmid crabs in the two habitats in order to better understand crab spatial distribution.ResultsThe two intertidal belts differed in terms of floral composition and crab species abundance. The eulittoral zone was strongly dominated by Neosarmatium smithi, while within the elevated littoral fringe four sesarmids (N. smithi, N. asiaticum, N. malabaricum and Muradium tetragonum) were more evenly distributed. At both levels, all sesarmids showed to collect significantly more Bruguiera spp. and Rhizophora apiculata leaves than Excoecaria agallocha ones. There was no temporal segregation in feeding activity among the four species, resulting in a high interference competition for leaves. Regardless of the habitat, N. smithi was always successful in winning inter-specific fights.ConclusionsOur results showed that the elevated littoral fringe was more crowded with crabs, but was less favourable in terms of food availability and environmental conditions. The dominance of N. smithi in gathering mangrove leaves suggests that this species may segregate the other sesarmids into less favourable habitats. The present data strongly suggest for the first time that interference competition for food can contribute to shape mangrove crab spatial distribution.

Distribution of larval crabs (Eriocheir sinensis) and relationship with oceanographic features in the Yangtze Estuary

ABSTRACTEriocheir sinensis, the Chinese mitten crab, has decreased dramatically in the Yangtze Estuary in recent years. Distribution of mitten crab larvae in the Yangtze Estuary and the influence of oceanographic features on their densities were analyzed based the samples collected from 27 stations in March, April and May 2013–2015. Results showed zoeae I and II began to appear in March, zoeae III and IV in April, and zoeae V and megalopae in May. The spatial patterns of zoeae II, III and IV were identified as having a highly clustered distribution. Habitats located near the mouth of the North Branch were mainly hotspots of each stage larvae. Both biotic (zooplankton biomass) and abiotic variables (water temperature and depth) had significant impacts on the larval densities. Compared with 1986–1988, the original nursery habitats have moved approximately 20–50′E towards the shore, and have locally lost the nursery function after the Three Gorges Dam (TGD) construction.

Habitat-mediated, density-dependent dispersal strategies affecting spatial dynamics of populations in an anthropogenically-modified landscape

A major challenge in managing natural populations in ecosystems is understanding and predicting the complexity and consequences of population dispersal. Although many studies have documented the importance of conspecific density and habitat quality in the dispersal process, we lack an understanding of how to integrate these factors in determining the spatial dynamics of populations or how habitat quality can mediate density-dependent dispersal. In this study, we propose a Habitat-mediated, Density-dependent, Spatial Population Dynamics model (HD-SPDM), in which we combined a Habitat Suitability Index (HSI) with a migration function, to explore the emergent effects of habitat mediated, density-dependent dispersal strategies on the spatial dynamics of a population. Our results show that habitat condition (based on HSI score) can influence ranges in conspecific density (which in turn can alter spatial patterns of populations distributed in homogeneous patches). We tested this model using the spatial distribution of Chinese mitten crab in the Yangtze River Estuary, which has been subjected to excessive sea reclamations over time, this allowed us to obtain insight into spatial distribution of population by determining how habitat-mediated, density-dependent dispersal at a small scale interacts with habitat heterogeneity and fragmentation at a landscape scale. We found that each progressive sea reclamation reduced suitable habitat area and habitat connectivity in the estuary. However, the model predicts that intermediate intensities of habitat compression and fragmentation could improve habitat utilization somewhat by facilitating population dispersal. Our model could be used to improve resource management of populations being increasingly impacted by anthropogenic alterations.

Сезонное распределение камчатского краба в районе губы Зелёная Баренцева моря

Сезонное распределение камчатского краба в районе губы Зелёная Баренцева моря

Filling missing links in albuneid crab distributions (superfamily Hippoidea) in the Bay of Bengal, eastern Indian Ocean

Abstract Albuneid crabs are specialized and active sand-burrowing organisms. Despite their substantial diversity, their ability to avoid fishing gear leads to “under collection” and a discontinuous record of distribution. The present study documents the first distributional record of Albunea occulta Boyko, 2002 from the Bay of Bengal, eastern Indian Ocean. Albunea thurstoni Henderson, 1893 is also recorded for the first time from the area, i.e., from the Gulf of Mannar, southwestern Bay of Bengal. This study further reports variation in morphological characters, especially in the carapace grooves (CG) from previous records and across specimens from different regions. Morphometric characters were found useful in species discrimination, which is explained as well.

Dynamics of snow crab (Chionoecetes opilio) movement and migration along the Newfoundland and Labrador and Eastern Barents Sea continental shelves

This study uses survey and tagging data and cluster analysis to interpret dynamics of ontogenetic movements and seasonal migrations in snow crab (Chionoecetes opilio) along the Newfoundland and Labrador (NL) continental shelves. Most historic literature from Atlantic Canada suggests snow crab undertake small-scale ontogenetic movements while observations of seasonal migrations had been near-exclusive to the inshore. Information on both types of movement in the most spatially expansive offshore region of Atlantic Canada, in NL, was lacking. We find that that both ontogenetic movements and seasonal migrations occur in most areas of the NL offshore, with ontogenetic movements generally down-slope and seasonal migrations generally up-slope. Conservative estimates of average ontogenetic movements range from 54 to 72 km for both males and females in the largest offshore regions while seasonal migrations are slightly smaller, with two independent studies on the Grand Bank producing average estimates of 43–46 km and an adjacent tagging study in a smaller inshore bay producing an average estimate of 25 km. Ontogenetic movements appear associated with a search for warm water while seasonal migrations appear associated with both mating and molting in shallow water. On average, morphometrically mature crab of both sexes move less vertical distance than morphometrically immature crab during seasonal migrations. We investigate plausible explanations for ontogenetic movements and spring migrations and detail how bottom temperature affects crab distribution and life history dynamics. We further document movement patterns from tagging studies on the burgeoning snow crab stock in the Eastern Barents Sea toward establishing consistencies in species behaviour on the global scale. Finally, we discuss explanations for historical disparities in the literature between scales of movement for snow crab in the Eastern Bering Sea of Alaska versus Atlantic Canada and advance perspectives on life history theory for the species.

The catch characteristics and population structure of the brown crab (Cancer pagurus) fishery in the Isle of Man, Irish Sea

Brown crab contributes to small-scale fisheries in the Isle of Man and landings (495 t) were worth in excess of £0.5 million in 2012. The present study sought to fill evidence gaps needed to improve the scientific understanding of this fishery. Observer data were collected to examine the spatial and temporal variations in the size distribution and sex ratio of crabs around the Isle of Man. This study also aimed to evaluate the catch characteristics of brown crab using logbook data (2007–2012), observer data (2012–2013) and questionnaire survey data (2013). The sex ratio is highly variable in different areas across seasons and was perhaps indicative of migration patterns in relation to mating. This change was most notable with a strong increase in the proportion of females to the south and west of the Isle of Man in the autumn months. The depth and pot volume were important factors that influenced the catch per unit effort (CPUE). Future survey designs would need to ensure adequate spatial coverage of the east and west coast of the Isle of Man together with a seasonal sampling regime that captures the spatial change in the distribution and abundance of male and female crabs.

Microhabitat differences in crab assemblage structures in a subtropical mangrove estuary on Iriomote Island, southern Japan

Crab assemblage structures in sandy flat, muddy flat and mangrove forest microhabitats in a mangrove estuary of the Urauchi River, Iriomote Island, southern Japan, differed clearly among the three microhabitats, species and individual numbers being greater inside the mangrove forest than on the flats. A similarity index showed distinct differences in species composition among the microhabitat assemblages, primarily due to the differential distributions of dominant species, such as the soldier crab Mictyris guinotae, sentinel crab Macrophthalmus convexus and sesarmid crab Perisesarma bidens. A canonical correspondence analysis indicated that the differences likely arose from among-microhabitat differences in the physical environment, the mangrove forest being characterized mainly by structurally complex mangrove roots, lower soil porewater temperatures and higher relative substrate elevation, the sandy flat by lower organic content of the sediment and higher porewater oxygen amount, and the muddy flat by higher levels of sediment water and organic material. The findings suggested that microhabitat-related physical differences are important factors determining crab distribution patterns in mangrove estuaries.

The Relative Importance of the Sedge Island Marine Conservation Zone for Adult Blue Crabs in Barnegat Bay, New Jersey

ABSTRACT Jivoff, P.R.; Moritzen, L.; Kels, J.; McCarthy, J.; Young, A.; Barton, A.; Ferdinando, P.; Pandolfo, F., and Tighe, C., 2017. The relative importance of the Sedge Island Marine Conservation Zone for adult blue crabs in Barnegat Bay, New Jersey. In: Buchanan, G.A.; Belton, T.J., and Paudel, B. (eds.), A Comprehensive Assessment of Barnegat Bay-Little Egg Harbor, New Jersey. Marine protected areas have become an important tool for the management of commercially important species. The Sedge Island Marine Conservation Zone (SIMCZ) in Barnegat Bay is 15 years old, but its effectiveness has never been assessed. This study evaluated the relative importance of the SIMCZ for adult blue crabs by comparing the abundance and size frequency distribution of crabs inside the SIMCZ with physically similar locations outside the SIMCZ that (1) were nearby, providing straight-line access to Barnegat Inlet but varying in habitat, and (2) varied in distance from an inlet but shared the same habitat. The SIMCZ contain...

Vertical distribution of snow crab (Chionoecetes opilio) pelagic stages in the Gulf of St. Lawrence (Canada) and effect of temperature on development and survival

AbstractKnowledge of the vertical distribution, thermal habitat, and growth of the larvae of the cold stenothermic snow crab (Chionoecetes opilio) is incomplete and inconsistent. This study explored aspects of the vertical distribution and development rate of larvae from eastern Canada. In the Gulf of St. Lawrence (GSL), during 2002, the mean vertical positions of the snow crab zoeae I and II larvae were recorded within and above the permanent thermocline and in close association with the depth of strong density discontinuities in the stratified water column. No statistically significant differences were detected between nighttime and daytime vertical positions. The water temperatures at the centre of the larvae distributions were 2–3 °C in late May in the colder northern GSL and 7–8 °C in June in the warmer southern GSL. Data from the literature and from a rearing experiment in 2014 were used to develop functions linking development and survival to water temperature. Assuming the snow crab larvae remain in the upper mixed layer until final metamorphosis, development may last 2.2–4 months depending on hatch time and location. Development would be prolonged by several weeks if premolt megalopae move into and reside in the deeper, colder waters as appears to be the case. A relative survival index suggests that optimum temperature for development is around 10.8 °C, 9.5 °C, and 8.7 °C for snow crab zoea I, zoea II, and megalopa, respectively. These results should contribute to modelling efforts that aim to evaluate the extent of larval drift and location of potential settlement areas, as well as the potential impact of climate change on snow crab in the North Atlantic.

Larval cycle, ecology and distribution of the red mangrove crab ( Ucides occidentalis ) in the Gulf of Guayaquil, Ecuador: understanding multiple impacts on fishery sustainability

Larval cycle, ecology and distribution of the red mangrove crab ( Ucides occidentalis ) in the Gulf of Guayaquil, Ecuador: understanding multiple impacts on fishery sustainability

Shore to landward transect burrow diversity of fiddler crab in a tropical intertidal coast of Chittagong in Bangladesh

Burrows indicate the abundance and distribution of fiddler crab in an intertidal coast that varies with structure and morphology within intertidal habitats. We observed fiddler crab burrow density and characters (burrow length, depth, diameter and volume) within randomly selected six 1m2 quadrate from three intertidal habitats: higher saltmarsh, mangrove pool (a small ditch distributed within mangrove) and mangrove land through field surveys in a coast of Chittagong, Bangladesh. Burrows were observed and counted for density estimation, and burrow characteristics were studied through excavating 10 representative burrows from each quadrate of each habitat. Spearman correlation was used to relate between the distances (from shore towards land) and burrow characters. Transect starting from saltmarsh as base towards mangrove land showed burrow density decreased from shore to higher intertidal habitat. Simultaneously, higher burrow length and diameter were observed landward and contrariwise shoreward. Burrow prevalence in mangrove pools represents fiddler crabs are abundant within land and shore interface presumably due to the dual privilege of easy burrowing and moist condition required for gill ventilation.Res. Agric., Livest. Fish.4(2): 131-140, August 2017

Habitat use of globally threatened juvenile Chinese horseshoe crab, Tachypleus tridentatus under the influence of simulated intertidal oyster culture structures in Hong Kong

Abstract Little is known about the ecological impacts of oyster culture structures on intertidal communities. In the present study, distribution and movement patterns of juvenile Chinese horseshoe crab, Tachypleus tridentatus were assessed on a mudflat at Ha Pak Nai in Deep Bay, Hong Kong. As the traditional bottom‐laying method of using concrete posts as cultch for collecting oyster spat is a common practice in Hong Kong, structurally similar bricks were used to simulate the potential effects of cultch on intertidal flats. Over the two‐month experimental period, all the tested sediment physico‐chemical characteristics, including median particle size and total organic content, remained unchanged among the treatment areas. However, juvenile densities and foraging trails at low‐ and high‐density brick areas were significantly lower/shorter compared with the adjacent bare areas. Such effects were more evident for larger individuals since significant correlations were found between foraging distance and juvenile prosomal width in no‐brick areas, but not the low‐ and high‐density brick areas. In addition, most juveniles (&gt; 95%) were observed feeding along the outer boundaries of brick areas. Such findings imply that the extensive artificial structures in oyster cultivation sites could induce physical disturbance and alter the habitat use of juvenile horseshoe crabs in the intertidal zone. Considering the high conservation value of Chinese horseshoe crabs, appropriate mitigation measures should be implemented to buffer the detrimental effects on horseshoe crabs and other marine organisms of conservation concern that utilize intertidal habitats as nursery and hatchery grounds.

Impact of bottom water temperature change on the southernmost snow crab fishery in the Atlantic Ocean

Snow crab populations are found in the Northern Atlantic, Arctic and Pacific Oceans. Snow crab are generally considered to be a stenothermic species with distributions constrained by the available thermal habitat. Crab fishing area 4X on the western Scotian Shelf is at the southernmost extent of Snow Crab distribution in the Northwest Atlantic. Bottom temperatures in this area provide very limited snow crab habitat. An incursion of warm slope waters flooded the western Scotian Shelf in 2011/2012 and created positive temperature anomalies. These warmer bottom temperatures appeared to have had a negative impact on some life stages of snow crab in local populations, with juvenile stages being the most affected. Evidence of this decrease was supported by various fisheries independent and dependent data sources. Though 4X snow crab populations are now increasing, likely due to immigration from an adjacent snow crab fishing area, this warm water event was very detrimental to the commercial fishery in the area.

Environmental Drivers of the Spatial and Temporal Distribution of Spawning Blue Crabs Callinectes sapidus in the Western Gulf of Mexico

AbstractThe blue crab Callinectes sapidus is an economically important shellfish found in the Gulf of Mexico and elsewhere. Recent declines in abundance of this species have driven progressive management actions throughout its range, including protection of spawning females by establishing “no‐take” zones on the Atlantic coast. To date, no‐take zones have not been established in the western Gulf of Mexico, although annual closures associated with mitigation of derelict traps exist in both Texas and Louisiana. In this study, we used long‐term data acquired via fishery‐independent sampling by the Texas Parks and Wildlife Department to assess spatial and seasonal distribution of spawning females in order to inform future evaluations of no‐take areas. The presence of spawning females was modeled statistically by using water quality and spatial variables as predictors. Distance to the nearest Gulf pass was the most reliable predictor of presence, accounting for over 43% of the deviance observed in models from two independent sampling eras. Salinity (&gt;21% of deviance) and temperature (&gt;12% of deviance) were also reliable predictors, and the values of salinity and temperature that were associated with peak presence remained consistent over an approximately 30‐year span despite increasing mean annual values of both variables through time. Peak presence in spawning grounds now occurs in early spring (March–April), contrasting with historical peak presence in the summer (June–July). These data imply seasonal shifts in spawning behavior despite relative spatial consistency through time, suggesting that Gulf pass areas would be ideal for protection of spawning blue crabs via no‐take zones if such a measure is deemed necessary.Received March 6, 2017; accepted May 18, 2017 Published online July 19, 2017

Effect of Environmental Factors on The Relative Fitness and Spatial Distribution of Mangrove Crabs (Scylla spp) in Blok Bedul Segoro Anak, Alas Purwo National Park, Indonesia

The mangrove forest are natural and renewable. resources Mangrove has the physical, chemicaland biological function which highly support the fulfillment of human needs and serve as a bufferbalance of the ecosystem in coastal areas. One of the functions associated with the mangrovebiological existence as a source of diversity of marine life. Marine life is affected by the presenceof mangrove forests among mangrove crab (Scylla serrata) to maintain the ecological balance andcause the energy cycle running fast. This study aims to determine the condition of environmentalfactors, the relative fitness and spatial distribution of mangrove crabin the mangrove forests BlockBedul Kali Segoro Alas Purwo National Park. Data from the study are described and classified bysimilarity of environmental factors, then performed multiple linear regression betweenenvironmental factors with relative fitness and spatial distribution of mangrove crabs. The resultsshowed that the average relative fitness mangrove crabs at all the research station is 69 with astandard deviation of 13.51. Spatial distribution of mangrove crab at any observation station isless than 1, so it can be concluded that the distribution is uniform. Environmental factors withrelative fitness mud crab significant correlation, but no significant correlation betweenenvironmental factors with the spatial distribution of mangrove crabs.&#x0D; Keywords: Relative Fitnes Crab Mangrove, Mangrove Crab Spatial Distribution, Alas Purwo National Park