Callinectes exasperatus

Abstract: From 1979 to 1983 nine species of Portunidae were identified in the estuarine-bay complex of Santos. Callinectes bocourti, Callinectes danae, Callinectes exasperatus and Callinectes sapidus occurred in the estuary and bay while Callinectes larvatus, Cronius ruber and Portunus spinimanus, only in the bay. Arenaeus cribrarius and Callinectes ornatus were found in the bay and also off the bay. In the estuary were found only species of the genus Callinectes, while in the bay were collected all the Portunidae sampled. Callinectes danae was the dominant species, with 92% of the specimens collected.

Abstract: Distribution patterns are defined for 20 brachyuran crab species of Laguna de Terminos based on the range of salinity and the habitats occupied by each. Habitats include unvegetated soft substrates, macroalgae, and sea grasses. "Wide" and "restricted" distributions relate species abundance to a wide and a narrow salinity range, whereas "associated with the habitat" and "not associated with the habitat" consider the presence of a species in one or several types of habitat. Fourteen species were grouped in the restricted and associated with the habitat pattern, of which the 3 spider crabs and the 10 mud crabs were associated with submerged aquatic vegetation in salinities above 18‰, and the swimming crab Callinectes exasperatus was distributed in an adjacent limnetic lagoon on unvegetated soft substrates. The mud crab Dyspanopeus texanus was placed in the wide and associated with the habitat pattern, since it is a euryhaline species and was always found on macroalgae and sea grasses. Three other swimming crabs and two other mud crabs were found on all sorts of substrates along a wide range of salinity and were included in the wide and not associated with the habitat pattern. Six faunistic groups were formed after analysis of the abundance data, using an ordination method with axes defined by salinity and type of habitat. Four functional guilds of brachyuran crabs are proposed, based on the 3 distribution patterns, the 6 faunistic groups, and the 2 subsystems and 4 areas previously described for the lagoon. Guild A grouped 2 swimming crabs and 1 mud crab distributed along the areas of the lagoon directly influenced by river runoff, where detritus-rich unvegetated soft substrates and macroalgae are common. Guild B included: (1) the 3 spider crabs and most of the mud crabs of which seven restricted and associated with the habitat species congregated in the northcentral-northeastern subsystem of the lagoon, where the greatest heterogeneity of habitats, dense sea-grass beds and poly-euhaline environments, is common; (2) 5 restricted and associated with the habitat species mostly distributed in this subsystem were also collected in areas influenced by river runoff during the dry seasons when salinity was above 24‰; and (3) 2 wide and not associated with the habitat species were mostly found in this subsystem, but extended their distribution to areas without submerged vegetation and lower salinities. Guild C was represented by D. texanus, which was found throughout most of the lagoon on macroalgae and sea-grass beds. Guild D included Callinectes sapidus and C. similis that were distributed throughout the lagoon independently of a particular type of habitat.

Abstract: This paper is the first record of the blue crab, Callinectes exasperatus, in European waters and the first record for this species out of its natural distribution. Due to the similar morphology with Callinectes sapidus, a widely extended invader in the Atlantic, Mediterranean and Pacific waters, the initial determination based on morphological characters was further confirmed by DNA barcode analysis. A possible introduction vector is also discussed.

Abstract: In order to improve the efficiency of soft-shell crab production, we investigated whether it is technically viable to increase harvesting rates of soft-shelled crabs of the species Callinectes danae and C. exasperatus by selecting animals based on macroscopic molt signs and maintaining them in specific facilities. The study was conducted in three stages. In the first stage, macroscopic anatomic changes possibly related to the molting cycle identified under laboratory conditions. In the second stage we used the macroscopic clues observed in the first assay to select premolt animals harvested from their natural environments. Yet in this stage of the work, the relationship between the macroscopic changes and the microscopic signs of molting was evaluated. Lastly, an assay verified the technical feasibility of increasing the fraction of soft-shells in the total catch by selecting and maintaining premolt swimming crabs of species C. danae and C. exasperatus in specific facilities until the molt. Our results indicated that we can macroscopically identify, and therefore select, individuals in premolt phases II, III and IV that will soon molt, but further investigations are necessary to identify the requisite conditions for successful molting of individuals in premolt phase I.