Crab Carapace Research Articles

Upcycling Shellfish Waste: Distribution of Amino Acids, Minerals, and Carotenoids in Body Parts of North Atlantic Crab and Shrimp.

The snow/pink crab (Chionoecetes opilio) and Northern shrimp (Pandalus borealis) are widely distributed in the North Atlantic Ocean. During processing/consumption, about 80% of the harvest is discarded as processing waste, which is a rich source of protein, chitin, minerals, and carotenoids. This study, for the first time, investigated the proximate composition and individual amino acids, minerals, and carotenoids from different body parts (carapace, shoulder, claw, tip, and leg) of snow crabs and shrimp shells. Shrimp proteins were found to be abundant and well-balanced in their amino acid composition. Compared to shrimp shells, a lower content of amino acids was found in the snow crab, depending on the part of the shell used. Moreover, crab shells, mainly crab claws, contained a higher (p < 0.05) level of chitin compared to shrimp shells. Seven micro-elements (Mn, Fe, Cu, Zn, As, Ba, and Ce) and six macro-elements (Ca, Na, K, Mg, P, and Sr) were identified using inductively coupled plasma-mass spectrometry (ICP-MS). Among them, calcium and iron were higher in crab carapaces (p < 0.05), followed by shrimp shells and other crab shell segments. Additionally, shrimp and crab carapaces contained a significant level of carotenoids, and these were mainly composed of astaxanthin and its mono- and diesters, along with zeaxanthin, astacene, canthaxanthin, and lutein. Thus, this investigation provides detailed information to allow upcycling of shellfish waste and addresses the knowledge gap concerning the availability of various nutrients in different crab sections and shrimp shells.

Feature Extraction and Recognition of Chinese Mitten Crab Carapace Based on Improved MobileNetV2

Feature Extraction and Recognition of Chinese Mitten Crab Carapace Based on Improved MobileNetV2

Occurrence of parasitism promoted by Myzobdella lugubris Leidy, 1851 (Annelida: Piscicolidae) in Callinectes bocourti (Crustacea: Portunidae): A report of invasive leech in Brazilian Amazon province

This study reports the presence of high parasitic load by Myzobdella lugubris Leidy, 1851 in the swimming crab Callinectes bocourti A. Milne-Edwards, 1879 from Amazon mangrove. We sampled the swimming crabs using a baited trap, between January and June 2023, in Santa Maria River, located in the municipality of Curuçá, state of Pará, Brazil (geographical coordinates 0°40′3.705”S, 047°54′43.405”W). After sampling, each swimming crab was individually placed in plastic containers for the count of leeches per individual. In the laboratory, the specimens were sexed, measured (parasite and host) and fixed in 70% alcohol. For the leech species identification, macroscopic techniques were combined with light microscopy (LM) and scanning electron microscopy (SEM). We examined 86 specimens of C. bocourti (75 males and 11 females) in a ratio of 1 M:0.14 F, all infested with leeches. In total, 186 leech specimens were collected, ranging from 1 to 21 leeches per host. Leeches oviposited the cocoons in greater quantities in ventral area of swimming crab carapace (32%), followed by dorsal area of carapace (29.09%), chelipeds (24.34%) and ambulatory legs (14.57%). The presence of M. lugubris is a risk to the health of the host, once it may transmit a range of diseases to aquatic organisms, and subsequently risk to human health.

MODIFIKASI DINDING BUBU LIPAT UNTUK MELOLOSKAN RAJUNGAN YANG BELUM LAYAK TANGKAP

Increasing of fishing pressure poses a serious threat to the sustainability of blue swimminng crab resources. Trap design modifications are needed to improve size selectivity and to release under size crabs. This study aimed to determine the type of wall modification of collapsible trap that is effective in excluding under size blue swimming crab. Laboratory observations were conducted using four escape vents treatments and three different mesh sizes. The escape gap used are rectangular, square, circular and oval respectively. Moreover, the mesh sizes used are 2.0 inches, 2.5 inches and 3.0 inches. Descriptive analysis and scoring were used to determine the most effective type of wall trap modification to be used in the blue swimming crab fishing. The results showed that the rectangular escape gap has better effectiveness than other shapes with the percentage of crabs that pass through at 86.7%. The wall modification using a 3.0-inch mesh size had better performance than the other modification types with a total score of 19. Collapsible trap with a 3.0-inch mesh wall was able to escape 86.7% of the crabs with an escape time of only 11.2 seconds and an average escaped crab carapace width of 78 mm. Keywords: Collapsible trap, escape gap, environmentaly-frendly fisheries, mesh size of trap wall

POPULATION PARAMETERS OF BLUE SWIMMING CRAB PORTUNUS PELAGICUS IN THE TIWORO STRAIT, SOUTHEAST SULAWESI

The blue swimming crab (Portunus pelagicus) has a wide distribution in the fishing ground waters for fishermen's activity in the Tiworo Strait. The coastal area of Tiworo Strait has quite a lot of crab potential. Therefore, it is used as one of the pilot locations for sustainable crab management projects of the Indonesian Blue Swimming Crab Association (APRI). Growth, total mortality, natural death, fishing mortality, and the exploitation rate were the population parameters of crabs that need to be known so that management can be carried out in a sustainable manner of fisheries. A study on the population parameters of crabs has been conducted in the Tiworo Strait, based on carapace width frequencies data collected from Juli to December 2021 and analyzed using FISAT (FAO-Iclarm Stock Assessment Tool) II. The total sample is 7,809 samples, where the number of male blue swimming crabs is 3,295 samples and 4,514 females. The average size of the blue swimming crab carapace width caught was 107.57 mm for males and 110.65 mm for females. The results of the study showed that the growth rate (K) was 1.01/year, the total mortality rate (Z) was 0.67/year, the natural death rate (M) was 1.25/year, and the fishing mortality rate was 0.58/year. The exploitation rate (E) of blue swimming crab was 0.86, which showed symptoms of over–exploitation, so the management of crabs in these waters must be carried out more carefully to sustain the availability of crab resource stocks. &#x0D; Keywords: blue swimming crab, width, weight, Tiworo Strait

Bycatch reduction devices exclude diamondback terrapins and maintain blue crab catch in two Virginia tidal creeks

AbstractObjectiveThe diamondback terrapin Malaclemys terrapin is frequently caught as bycatch in both commercial and recreational blue crab Callinectes sapidus fisheries throughout its range along the Atlantic and Gulf coasts of North America. Bycatch reduction devices (BRDs) are plastic or wire rectangles mounted in the entrance funnels of crab traps, designed to exclude terrapins while still allowing crabs to enter. In this study conducted in two tidal creeks in Virginia, USA, we assessed the effectiveness of four BRD designs, including two novel oval designs, against control traps with no BRDs.MethodsWe tested four replicates of each of the five trap treatments (1.75‐inch oval BRD, 2‐inch oval BRD, 1.75‐inch rectangular BRD, 2‐inch rectangular BRD, and a control trap without a BRD) in each tidal creek, for a total of 20 traps per creek and 40 traps total. We fitted traps with wire chimneys that extended above the high tide water line to allow trapped terrapins to surface for air. For eight weeks during summer 2021, we baited traps with Atlantic Menhaden Brevoortia tyrannus each day, beginning on Monday. Tuesday–Friday, we emptied traps of any animals inside, and recorded terrapin sex, terrapin carapace length, terrapin carapace width, and terrapin shell height, as well as blue crab carapace length.ResultWe found that all four BRD designs were highly effective at excluding terrapins and maintaining crab catch when compared to control traps. We found a significant difference (p = 0.003) in catch per unit effort (CPUE) of diamondback terrapins among treatments, with the control group (those without BRDs) having the highest CPUE (0.97 ± 0.18). All traps fitted with BRDs decreased terrapin capture significantly compared to the control group. Oval BRDs excluded more terrapins than their rectangular counterparts with the same height dimension, although these differences were not significant. We found no significant difference in CPUE of blue crabs among treatments (p = 0.392), or in the size of legal crabs caught in each treatment (p = 0.216).ConclusionThis study provides evidence of the effectiveness of both rectangular and oval‐shaped BRDs to exclude terrapins and maintain crab catch in Virginia waters, where BRDs are not currently required.

Orange mud crab (Scylla olivacea) exploitation at Sorong waters

Mangrove forests along the vast coast of West Papua serve as the habitat for mud crabs, which are high-value economic resources marketed to various regions in Indonesia. However, intensive utilization impacts the sustainability of mangrove crab populations, especially orange mud crabs (Scylla olivacea). Exploitation studies need to be conducted for further use to manage crab resources. This study was conducted for six months, from April to September 2021, with a sample of 2,971 orange mud crabs. Data analysis was carried out using crab carapace width (CW) data to predict resource exploitation and sustainability. The caught orange mud crab size was 80-190 mm, with natural mortality (M) lower than fishing mortality (F). The exploitation of this crab has attained E = 0.72, which proves that overfishing. We can do the management of orange mud crabs by observing the size of mature gonads and spawning areas to provide an opportunity to increase the population in the waters.

Stable isotopes of archaeological and modern semi-terrestrial crabs (Potamon potamios) provide paleoecological insights into brachyuran ecology and human resource acquisition in late Holocene Jordan

Archaeological remains of brachyurans (e.g. crabs) are often overlooked as potential paleoenvironmental and paleoclimatical proxies in contrast to other marine and terrestrial invertebrates such as mollusks and landsnails. The potential for fine-scale regional paleoclimate reconstruction based upon these organisms' behavioral ecology has yet to be examined. We present novel isotopic analyses of the remains of a semiterrestrial freshwater crab (Potamon potamios) endemic to southwest Asia recovered from the archaeological site of Khirbat al-Mudayna al-’Aliya (KMA). KMA lies on a southern tributary of the Wadi al-Mujib in the Hashemite Kingdom of Jordan, approximately 40 km east of the Dead Sea. Excavations here recovered architecture, artifacts, and ecofacts dating to a single-period occupation during the early Iron Age (∼1000 cal BCE). Oxygen and carbon isotopes from these brachyuran remains were analyzed in conjunction with a two-year isotopic and morphometric study of the modern potomonautid population near the archaeological site and at nearby wadi systems to assess whether the isotopic values of modern crab populations correlated with variables such as temperature, including isotopic study of the pools in which crabs were found. In turn, these data could be used to reconstruct paleoclimate or paleoenvironment in the archaeological population. The high correlation in oxygen isotope values between crab carapaces and the water of the pools in which they were sampled suggest that variability in isotopic values of crab specimens recovered from KMA is tracking ancient human capture of these organisms across potentially different pools. Further, intra-year variability in isotopic values in modern crab carapaces as well as the similarity of isotopic values across wadi systems with different environments suggest that P. potamios remains cannot be used as reliable paleoenvironmental indicators. The implications of this research will have significance for archaeologists and other researchers in the study of paleoenvironment and paleoecology, and bears upon human mobility, resource acquisition, and human-nonhuman animal relationships.

PH-Dependent Behavior of Novel 5-FU Delivery System in Environmental Conditions Comparable to the Gastro-Intestinal Tract

A biogenic carrier for 5-fluorouracil (5-FU) loading and subsequent tableting as a new drug formulation for slow release has been proposed using the biomineral from blue crab carapace. Due to its highly ordered 3D porous nanoarchitecture, the biogenic carbonate carrier could achieve increased effectiveness in colorectal cancer cure provided that the formulation would successfully pass through the gastric acid conditions. Following the recently proven viability of the concept by demonstrating the slow release of the drug from the carrier using the highly sensitive SERS technique, here we investigated the 5-FU release from the composite tablet drug in pH conditions replicating the gastric environment. The released drug from the tablet was studied in solutions with three relevant pH values, pH 2, pH 3, and pH 4. The 5-FU SERS spectral signature for each pH value was used to build calibration curves for quantitative SERS analysis. The results suggested a similarly slow-releasing pattern in acid pH environments to that in neutral conditions. Although biogenic calcite dissolution was expected in acid conditions, the X-ray diffraction and Raman spectroscopy showed preservation of calcite mineral along with the monohydrocalcite during acid solution exposure for two hours. The total released amount in a time course of seven hours, however, was lower in acidic pH solutions, with a maximum fraction of ~40% of the total amount of loaded drug, for pH 2, as opposed to ~80% for neutral values. Nonetheless, these results clearly prove that the novel composite drug retains its slow-releasing character in environmental conditions compatible with the gastrointestinal pH and that it is a viable and biocompatible alternative for oral delivery of anticancer drug to reach the lower gastro-intestinal tract.

King crab gills as a new source of chitin/chitosan and protein hydrolysates

This is the first report on the physicochemical properties of chitin obtained from gills of the king crab Paralithodes camtschaticus. In the present study, we investigated the chemical composition of red king crab gills and considered methods of its complex processing to obtain chitin and enzymatic protein hydrolysates. The gills contained approximately 21 % chitin in terms of dry matter. For the first time, the gills of the king crab were investigated as a source of chitin and chitosan.Chitin was isolated from crab gills using chemical and enzymatic methods. The physicochemical properties of chitin and chitosan from the gills were investigated. By performing infrared spectroscopy and X-ray phase analyses, the chitin present in the gills was established to be α-chitin. The physical and chemical properties (degree of deacetylation, molecular weight and crystal structure) of gill chitin and chitosan were absolutely similar to those of crab shell.Crab gills can be used as an additional source of chitin in the integrated processing of king crabs. The yield of chitin from the gills is up to 45 % of the yield of chitin from the crab carapace.

Pilot-scale phosphate recovery from wastewater to create a fertiliser product: An integrated assessment of adsorbent performance and quality

Eutrophication and the predicted limited future availability of rock phosphate has triggered the increased development of phosphorus (P) recovery technologies, however, for remote regions, recovery solutions are still limited. Here, we report on a novel pilot-scale technology (FILTRAFLOTM-P reactor) to recover phosphate (PO43−) from wastewater effluent through a filtration/adsorption process in a rural setting. This unit employs enhanced gravitational filtration through adsorption media (here, a novel KOH deacetylated crab carapace based chitosan-calcite material (CCM)) with continuous self-backwashing. Trials were designed to assess how the FILTRAFLOTM-P unit would operate under ‘real’ conditions (both at low and high PO43− levels), and to ascertain the effectiveness of the adsorbent to recover phosphate from final effluent. High removal was achieved at low phosphate concentrations, bringing the residual effluent PO43− level below 1 mg/L (EU limit for sensitive water bodies), while phosphate was efficiently harvested (at more than 50%) at higher PO43− levels. Surface microprecipitation and inner-sphere complexation were postulated as the main PO43− adsorption mechanisms through XRD, XPS and EDX elemental mapping. Further, a quality assessment of the P-enriched CCM (which could be used as a potential soil amendment) was undertaken to consider elemental composition, microbiological assessment and quantification of organic micropollutants. Quality analysis indicated ∼2.5% P2O5 present, trace levels (well below legislative limits) of heavy metals and extremely low levels of organic pollutants (e.g., PCBs, pharmaceuticals). No detectable levels of target bacterial pathogens were observed. Pot trials showed that ryegrass cultivated with the addition of the CCM adsorbent achieved higher plant dry matter and P concentration when compared to unfertilised controls, with a slow-release kinetic pattern. This study showed that CCM used with the FILTRAFLOTM-P pilot reactor has high potential to recover phosphate from effluents and encourage resource recovery via bio-based management of waste.

Crab contributions as an ecosystem engineer to sediment turnover in the Yellow River Delta

Burrowing crabs are widely distributed and have large populations in estuarine wetlands. Crab excavation can have potentially significant bioturbation effects on the vertical structure of sediments, and the processes of nutrients deposition and mineralization. However, the effects of crab micro activities on the geochemical cycling processes of the whole estuarine ecosystems are not clear, specifically the contributions of burrowing crabs to sediment and nutrients turnover in coastal ecosystems. Due to the lack of knowledge on crab burrowing behavior and borrow morphology, it is difficult to accurately estimate the excavation and turnover volumes of crabs. Therefore, this study examined the bioturbation activity of the crab Helice tientsinensis in western Pacific estuary ecosystems by analyzing their burrow morphology and local sediment properties. The common burrow shapes of Helice tientsinensis were J- and Y-shaped burrows. Burrow morphological characteristics such as total burrow depth, curve burrow length, burrow volume, and opening diameter significantly differed among tidal zones. Crab carapace size, water depth, soil hardness, and bulk density were the main factors driving burrow morphology. Sediment excavation by crabs was ~50 times greater than the deposition of sediment into crab burrows. The net transported amounts of sediment (31.66–33.18 g·d-1·m-2) and nutrients (total nitrogen: 0.075–0.090 g·d-1·m-2, total carbon: 3.96–4.55 g·d-1·m-2, and organic matter: 0.44–0.77 g·d-1·m-2) were mainly from the belowground sediment to the surface. These results highlighted the important role of crabs in sediment and nutrients cycling within coastal estuary ecosystems.

An evaluation of the preferences of the juvenile swimming crab, Portunus trituberculatus, for different structural properties of shelters

Crustaceans select shelters non-randomly, and their preferences may be mediated by the structural properties of shelters. Providing shelters is an effective approach to improving the survival of pond-raised crabs, but the structural properties of shelters that would significantly benefit the survival rate remain unclear. Here, a laboratory experiment was conducted to examine the preference of swimming crabs (Portunus trituberculatus) for three types of shelter with different depths, heights, and widths using an animal behavioral observation system. The residence time of crabs in each shelter was calculated, the changes in their preference were described by the program PFunc, and the correlations between the carapace width and preference function traits were analyzed. The results showed that juvenile swimming crabs (carapace width = 5.08 ± 0.34 cm) preferred shallow, high, and wide shelters, and the strongest preferences observed were for depth and height. There was a correlation between crab carapace width and preference function traits, which suggests that preferences became stronger as the carapace width increased. Height and width are the two major dimensions that need to be controlled when designing a shelter, and their value should be determined by the carapace width of the crabs. Providing the crabs with shelter at their preferred dimensions in the pond can prolong the residence time, which may help to reduce the frequency of agonistic encounters and improve the survival of the crabs.

Artificial Neural Network Modeling of Abrasion Loss and Surface Roughness of Crab Carapace Impregnated Coir Vinyl Ester Composites

Roughness plays an important role in determining how an object would be related with its environment. In tribology, rough surfaces easily obtain wear more quickly and have higher friction coefficients than smooth surfaces. Roughness is often a good analyzer of the performance of a mechanical component. This investigation is aimed to study the abrasion loss and surface roughness behaviors in crab carapace-filled coir fiber reinforced vinyl ester composites. The development of filler-impregnated fiber-polymer composites in recent years necessitated the evaluation and prediction of tribological behaviors in fiber reinforced composites. The composite fabrication was planned by varying the three fabrication parameters with three levels such as fiber length (10 mm, 30 mm, and 50 mm), fiber diameter (0.1 mm, 0.18 mm, and 0.25 mm), and content of crab carapace fillers (0%, 2%, and 4%) as per Design of Experiments (DOEs) in this current investigation. Low velocity integrated wear loss tests on composite samples were carried out, and also the average surface roughness is measured in the fabricated composites. Nonlinear regression equations were developed to study the correlation between tribological behaviors and fabrication parameters. The interaction effect of fabrication parameters was studied using ANOVA two-tail test and validated using response surface plots. In order to forecast abrasion loss and surface roughness behaviors, artificial neural network (ANN) models were constructed, and it was discovered that the produced ANN models effectively predicted the abrasion loss as well as surface roughness behavior within the given ranges.

Occurrence, infestation rate, and spatiotemporal distribution of the African pea crab (Afropinnotheres monodi) inhabiting Mediterranean mussels (Mytilus galloprovincialis) from southern Portugal

AbstractThe present study aimed to analyze the occurrence and prevalence, infestation rate and intensity, host–guest colonization pattern, morphometric relationships, and spatiotemporal distribution of the African pea crab (Afropinnotheres monodi) inhabiting the shell of Mediterranean mussels (Mytilus galloprovincialis) from the Algarve coast and Ria Formosa lagoon (southern Portugal). Sampling campaigns were performed with a trimestral periodicity in 2018–2019 and comprised 13 collecting sites distributed in the Ria Formosa, along the Algarve coast, and in an offshore mussel farm. Altogether, 10,109 individuals of M. galloprovincialis in a broad range of sizes (9.0–91.2 mm in shell length) were sampled, among which 571 host mussels (14.6–73.6 mm in shell length) contained a total of 598 individuals of A. monodi, corresponding to an infestation rate of 5.6% (prevalence rate of 5.9% due to multiple occurrences). The sample of pea crabs also covered an extensive range of sizes (1.7–14.5 mm in carapace width) and included eight juveniles, 163 males, and 427 females (82 hard females and 345 soft females, of which 128 were non‐ovigerous and 217 ovigerous). Overall, hard (13.9%) and soft (58.5%) females prevailed over males (27.6%), corresponding to female‐biased sex ratio of 1 male:2.6 females. In terms of infestation intensity, 95.4% of host mussels contained a single pea crab, with multiple infestations (two or three crabs inside a single mussel) being more frequent in the lagoon than along the coast. Morphometric relationships between host shell length and pea crab carapace width were highly correlated (r values ranged .218–.631), although there were no significant differences between sexes or female demographic categories and maturity stages. Overall, the present study provided further insights into the colonization of M. galloprovincialis by A. monodi.

Shape variation in the carapace of Chinese mitten crabs (Eriocheir sinensis H. Milne Edwards, 1853) in Yangcheng Lake during the year-long culture period

To evaluate whether ontogenetic development over the grow-out culture period can cause geographical plasticity of carapace shape in a certain region, geometric morphometric analysis was used, in this study, to determine the ontogenetic changes in the carapace morphology of Chinese mitten crabs (Eriocheir sinensis) originating from Yangcheng Lake, China, during a year of growth from coin-sized juveniles to market-sized adults. The morphological differences in the carapace throughout the year of culture were characterized using a 35-landmark point system. We used principal component analysis and linear discriminant analysis to determine morphological variation using thin-plate spline analysis and mesh deformation. During the growth process, the changes in the carapace were mainly concentrated in the third and fourth anterolateral teeth and on the M-shaped pattern. During the growth of male and female crabs throughout the year, the shape of the carapace changed considerably over the first six months. Afterwards, the shape of the carapace began to stabilize and could not be differentiated through discriminant analysis. This study is the first to use geometric morphometrics to analyze the ontogenetic changes in the carapace shape of E. sinensis crabs native to Yangcheng Lake. The results demonstrate that it takes a long time for the carapace morphology of native crabs to stabilize.

Substrate-Driven Phosphorus Bioavailability Dynamics of Novel Inorganic and Organic Fertilizing Products Recovered from Municipal Wastewater—Tests with Ryegrass

Municipal wastewater is a valuable source of phosphorus (P) for the production of fertilizing products, such as microalgae (MA), crab carapace material (CCM), P salt produced by chemical leaching of sludge (P salt CL), and sewage sludge ash produced by pyrolysis and the incineration of sludge (SSA PI). This study compares the P availability of these fertilizing products in three planting substrates (S1, S2, and S3) during a four-month growth period of perennial ryegrass. The unfertilized control in substrate S3 had a high and available P that masked the effect of the added fertilizing products. The P salt CL fertilizer exhibited the lowest shoot dry matter in the alkaline S2 substrate. Still, it can be used as a good source of P in both acidic and alkaline substrates, given that its shoot P content was among the highest in all substrates tested. The organic-rich fertilizing products, MA and CCM, are better suited for acidic substrates since a pronounced reduction in the shoot yield and P content was seen in the alkaline S2 substrate. In contrast, for the SSA PI fertilizer, the very small differences in shoot dry matter and P content in S1 compared to S2 indicated that it is suitable for both acidic and alkaline substrates. Four months were needed to observe the maximum shoot yields treated with these P fertilizing products. Considering that the substrate solution P (using Rhizons) for the P salt CL and MA fertilizers proved to be similar to shoot P uptake, Rhizon extraction could be used for assessing P bioavailability. The chemical composition of novel products indicated their potential to deliver not only P, but also other nutrients to plants. However, concentrations of inorganic contaminants in all products, except CCM, pointed out a possibility to pollute the environment by applying these fertilizers.

Burrow Morphology of Brachyuran Crab Dotilla blanfordi Alcock, 1900 from Gulf of Khambhat, Gujarat, India

The present study was conducted to understand the burrow morphology of brachyuran crab Dotilla blanfordi Alcock, 1900 at Dandi beach located in Gulf of Khambhat of Gujarat state, India. Burrows were selected randomly and their opening diameter was recorded. Diluted resin was poured in the burrows to generate burrow cast. If the occupant crab emerges out of the burrow, it was captured and carapace width and gender was recorded. The shapes of complete burrow casts were identified and measurements of various morphological characters of burrow cast were recorded. Total 7 different burrow shapes were identified, out of which single tube burrow was the most common as compared to other burrow shapes. The crab carapace width showed significant relationship with burrow opening diameter, burrow depth, burrow length and burrow volume. Juveniles (3.45 mm CW) were making burrow of all the seven shapes. Burrow depth, length and volume were significantly higher in adult crabs as compared to juveniles. No significant variation was observed between burrows of male and female individuals. The present study showed that burrow morphology is highly affected by the crab body size and also varies significantly with different life stages of the crab. Juveniles make shallow and simple burrows as their smaller gill areas stores lesser amount of respiratory water which needs to be changed frequently. However, adults make complex burrows to perform various tasks including copulation and reproduction.

Combining Knowledge Systems Helps Understand the Spatial Dynamics of Data-Limited Small-Scale Fisheries Systems in Brazil: A Methods Analysis

Mangrove habitats provide nursery, shelter, and feeding sites for many economically relevant fish, and invertebrates, such as crabs. Given the highly artisanal character and the patchy spatial distribution of small-scale fishing in mangroves, there is often little data available to inform management, potentially threatening the sustainability of this livelihood-supporting activity. This study assesses the combination of different data collection methods and of including published data in the analysis of the spatial dynamics. We examine crab fisheries in two sustainable-use protected areas as a case study to understand use patterns as indicated by a specific combination of mapping methods. Mangrove crab fishing grounds were mapped by overlaying crab gatherers’ tracked routes with maps produced during participatory-mapping-centered interviews. Information from the literature was used to spatialize crab carapace width and relate it to distance traveled by fishers. Results show that crabs tended to be larger if caught farther from the villages where fishers live. In terms of collection methods, even though GPS tracking is relatively time- and resource-consuming, incorporating some GPS tracking into participatory mapping helps overcome a downside of this type of mapping (e.g., lack of geographical precision) and identifies information that can be accessed through participatory techniques. This highlights the importance of linking different approaches in order to understand small-scale fisheries spatial dynamics.

Effect of acetic and citric acid solvent combination with cinnamon oil on quality of edible packaging from chitosan

Chitosan is one of the fishery by-products, which is extracted from shrimp and crab carapace. Chitosan can be processed into edible packaging. The nature of chitosan edible packaging is depended on the type of solvent used while extraction. Acetic acid produces a strong coating with good barrier properties but less elastic, while citric acid produces an elastic layer but has relatively low barrier properties and weak coating. Cinnamon essential oil can inhibit bacterial growth. This study aimed to obtain the best proportion combination of acetic and citric acid solvents which can improve mechanical properties and permeability of the edible packaging, also determine the effect of cinnamon essential oil in inhibiting Salmonella and S. aureus bacteria. The experimental design used a completely randomized design (CRD), with solvent combination treatment in preliminary research initially followed by chitosan and cinnamon essential oil addition in the subsequent research. Data showed that the best edible packaging properties were obtained from a combination of acetic and citric acid (2:2) with 30.67 MPa tensile strength, 65.35% elongation, 0.0422 mm thickness, and moisture permeability 3.02x10−10 g.m.m−2.s−1.pa−1. The concentration of 1.5 g of chitosan with 1.5% cinnamon essential oil can produce an antibacterial with 10.15 mm inhibition zone diameter in Salmonella sp. and 9.53 mm in Staphylococcus aureus