Extraction of chitin from edible crab shells of Callinectes sapidus and comparison with market purchased chitin

Chitin and its derived products have immense economic value due to their vital role in various biological activities as well as biomedical and industrial application. Insects, microorganism and crustaceans are the main supply of chitin but the crustaceans shell like shrimp, krill, lobsters and crabs are the main commercial sources. Chitin content of an individual varies depending on the structures possessing the polymer and the species. In this study edible crabs’ shells (Callinectes sapidus) were demineralized and deproteinized resulting in 13.8% (dry weight) chitin recovery from chitin wastes. FTIR and XRD analyses of the experimental crude as well as purified chitins revealed that both were much comparable to the commercially purchased controls. The acid pretreatment ceded 54g of colloidal chitin that resulted in 1080% of the crude chitin. The colloidal chitin was exploited for isolation of eighty five chitinolytic bacterial isolates from different sources. Zone of clearance was displayed by the thirty five isolates (41.17%) succeeding their growth at pH 7 on colloidal chitin agar medium. Maximum chitinolytic activity i.e. 301.55 U/ml was exhibited by isolate JF70 when cultivated in extracted chitin containing both carbon and nitrogen. The study showed wastes of blue crabs can be utilized for extraction of chitin and isolation of chitinolytic bacteria that can be used to degrade chitin waste, resolve environmental pollution as well as industrial purpose.

Larvae of the blue crab Callinectes sapidus Rathbun, 1896 (Decapoda: Brachyura: Portunidae) in the Balearic Archipelago (NW Mediterranean Sea)

The invasive blue crab Callinectes sapidus has been frequently recorded during the last years along the NW Mediterranean Sea, leading to established populations. Two megalopae of C. sapidus were found during two different oceanographic surveys in open waters of the Balearic Archipelago, in July 2005 and October 2011, previous to the first reference of adult specimens documented in the Balearic sub-basin. The analyzed environmental conditions of the sampling periods allowed us to hypothesize the likely introduction pathways, namely by maritime transport and surface currents. Furthermore, the recorded megalopae seem to enlarge the life history of C. sapidus in regard to its native area, where spawning peaks occur in late July and early August.

State of Blue Crab Callinectes Sapidus in the Lagoon of Orikum in Albania

Callinectes sapidus Rathbun, 1896, or as it is otherwise called blue crab, is an invasive species, which was reported for the first time to the Mediterranean Sea in 1949. It has been spread and adapted well to almost the entire Mediterranean and during the recent years even along the coast of the Adriatic Sea. Today it is considered as one of the worst invasive marine species in this region, with an impact on both biodiversity and socio-economic aspects. After a preliminary study on the distribution of blue crab in the Albanian coast, the aim of this study is to provide data on the presence and abundance of this species and to evaluate the population structure by measuring biometric parameters in the lagoon of Orikum. Blue crab observations and collections are conducted almost every month during the period 2012, 2014 and 2015 in the Orikum lagoon. Based on standard method of biometric parameters, measurements of weight, height and width of individuals collected during the study period in the Orikum lagoon were performed. During the study period questionnaires were distributed to local fishermen to collect information on the presence of the blue crab, asses its condition and its possible impact on other populations in the Orikum lagoon.

Updated checklist of semi-terrestrial and estuarine crabs (Crustacea: Decapoda: Brachyura) of Barbados, West Indies

Considering the growing threats to the biodiversity of small Caribbean islands (e.g., habitat loss and fragmentation, overexploitation, invasive species, and climate change), it is important to establish biodiversity inventories that serve as baselines for monitoring and evaluation of conservation efforts. In Barbados (West Indies), the most recent comprehensive taxonomic account of brachyuran crabs came from Rathbun (1921) reporting the specimens collected by the University of Iowa Barbados-Antigua Expedition in 1918. The present study fills the 100-year gap in knowledge by providing an updated taxonomic checklist of brachyuran crabs associated with semi-terrestrial and estuarine habitats in Barbados. A total of 245 specimens representing three superfamilies, six families, nine genera, and 13 species were collected over a period of 425 search-hours in twenty-seven sampling locations in semi-terrestrial and estuarine habitats of Barbados between September 2018 and November 2020. The families with the highest numbers of species identified were Gecarcinidae (3) and Portunidae (3), followed by Grapsidae (2), Sesarmidae (2), Ocypodidae (2), and Varunidae (1). The species Armases ricordi (H. Milne Edwards, 1853), Cyclograpsus integer H. Milne Edwards, 1837, and Callinectes sapidus Rathbun, 1896, are recorded here for the first time for Barbados.

POPULATION TREND OF THE INVASIVE BLUE CRAB CALLINECTES SAPIDUS RATHBUN,1896 IN PATOKU LAGOON.

The blue crab Callinectes sapidus is one of the 23 marine alien species reported for the Albanian coast so far (Beqiraj et al., 2012; Katsanevakis et al., 2011). The first scientific report on the presence of this species in the Albanian coast is in 2009, in Patoku Lagoon. The blue crab population in Patoku Lagoon had grown significantly by 2009 and the blue crab had started to be traded. The data collected in that year showed that this species is assessed to be established in the Patoku Lagoon (Beqiraj & Kashta, 2010). Special attention has been paid to the study of blue crab population in the following years during 2010 - 2015. The aim of this study is to evaluate the development and population trend of blue crab in the Patoku Lagoon referring to the data collected throughout years of study.

Factors Influencing Colonization and Survival of Juvenile Blue Crabs Callinectes sapidus in Southeastern U.S. Tidal Creeks

Tidal creeks along the southeastern U.S. and Gulf of Mexico coastlines provide nursery habitats for commercially and ecologically important nekton, including juvenile blue crabs Callinectes sapidus, a valuable and heavily landed seafood species. Instream and watershed urbanization may influence the habitat value that tidal creeks provide to blue crabs. We investigated natural and anthropogenic factors influencing juvenile blue crab occupancy dynamics in eight first-order tidal creeks in coastal North Carolina (USA). An auto-logistic hierarchical multi-season (dynamic) occupancy model with separate ecological and observation sub-models was fitted to juvenile blue crab presence/absence data collected over replicate sampling visits in multiple seasons at three fixed trapping sites in each creek. Colonization and survival are the processes operating on occupancy that are estimated with this formulation of the model. Covariates considered in the ecological sub-model included watershed imperviousness, the percent of salt marsh in each creek’s high tide area, percent salt marsh edge, site-level water depth, and site-level salinity. Temperature, salinity, and dissolved oxygen were covariates considered in the observation sub-model. In the ecological sub-model, watershed imperviousness was a meaningful negative covariate and site-level salinity was a positive covariate of survival probability. Imperviousness and salinity were each marginally meaningful on colonization probability. Water temperature was a positive covariate of detection probability in the observation sub-model. Mean estimated detection probability across all sites and seasons of the study was 0.186. The results suggest that development in tidal creek watersheds will impact occupancy dynamics of juvenile blue crabs. This places an emphasis on minimizing losses of natural land cover classes in tidal creek watersheds to reduce the negative impacts to populations of this important species. Future research should explore the relationship between imperviousness and salinity fluctuations in tidal creeks to better understand how changing land cover influences water chemistry and ultimately the demographics of juvenile blue crabs.

Improving of Gelling Capacity of Cooked Crab Meat Proteins

Cooked crab meat subjected to a cutting process can aggregate again, forming weak gels. The objective of this work was to determine the effect of two mixing methods, combined with the addition of the microbial enzyme TGase (MTGase) on the mechanical and functional properties of gels from washed or unwashed blue crab (Callinectes sapidus) meat. Live crabs were obtained from Laguna Madre, Tamaulipas, Mexico, and cooked at 120°C for 20 min before hand-picking the meat from the shell. Cooked meat was processed by mixing and cut at temperatures of 25 or 60°C, without (control) or 0.5% of MTGase. Then cooked at 90°C for 15 min. Changes in texture profile analysis, percentage of extractable water, and color were evaluated. The mixing method at 60°C allowed increasing the textural properties of the gels, and the addition of MTGase significantly improved the mechanical properties. The results allowed stablishing a viable technique to obtain restructured gels from cooked crab meat with no need to extract the soluble compounds responsible for their distinctive odor and taste which often affect the mechanical properties.