Blue Swimming Crab Portunus Segnis Research Articles

Comparison of lipid content and fatty acid profile of fresh and frozen blue swimming crab Portunus Segnis

The blue swimming crab Portunus segnis has a great economic interest in local and foreign fishing markets and is in high demand by consumers. The aim of the present work was to evaluate the change in total lipid (TL), fatty acids composition and nutritional quality indices (NQI) of the meat of blue swimming crab Portunus segnis after freezing at -18◦C for 15, 30, 60 and 90 days. The comparison of fresh and frozen crabs showed that freezing had significant effects on the nutritional quality of this marine product. Lipid peroxidation was enhanced during the freezing process. Total lipid content decreased significantly as a function of days of storage, especially from 30 days. A significant change was also observed in the fatty acid composition of frozen crab meat. During the freezing process, saturated fatty acids (SFA) increased significantly, while polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA) decreased. We can conclude that storage of blue crab P. segnis at -18◦C was not efficient enough for long preservation, as it has a strong effect on the deterioration of the nutritional quality of the meat over time. Frozen crabs should preferably be consumed within 15 days of storage. Our research targets both domestic and international consumers of this crab, with a specific focus on restaurants and hotels that incorporate this item into their menus. We recommend that consumers of this product exercise increased caution regarding the advantages and drawbacks associated with the freezing techniques employed.

Effect of Freezing Process on the Chemical Properties of Blue Swimming Crab Portunus segnis: Storage Stability and Acceptability

ABSTRACT The effect of frozen storage at a commercial temperature (−30°C) on the nutritional characteristics of the blue swimming crab Portunus segnis for a period of 120 days was investigated. Lipid and protein oxidation was investigated by analyses of peroxide value, thiobarbituric acid reactive substances, free fatty acids, and advanced oxidation protein products. Results showed significant lipid deterioration with extended storage time and changes in fatty acids composition and lipid classes. From a nutritional standpoint, it would be preferable for human consumption to eat frozen crabs for no more than 30 days as they retain a higher nutritional value.

The blue swimming crab Portunus segnis (Forskål, 1775) reaches the Adriatic Sea: a distant and disjointed occurrence

The blue swimming crab Portunus segnis (Forskål, 1775) reaches the Adriatic Sea: a distant and disjointed occurrence

Isotopic Niche and Trophic Position of the Invasive Portunid Portunus segnis Forskål, (1775) in Elounda Bay (Crete Island, Eastern Mediterranean)

There is a growing recognition that an advanced understanding of the trophic characteristics of an invasive consumer can provide important information on its ecological impact. In recent years, the blue swimming crab Portunus segnis, one of the earliest Lessepsian invaders, has considerably expanded its distribution range in the Mediterranean Sea, yet, its trophic habits in invaded areas remain scarcely investigated. In this study, we used carbon and nitrogen stable isotopes analysis (SIA) to determine the trophic position and isotopic niche of the crab compared with other representatives of the flora and fauna occurring in Elounda Bay (Crete). P. segnis showed a trophic position of 3.9, higher than the values determined by SIA or conventional gut content analysis in other areas of the Mediterranean Sea or in the native range. Crab specimens showed a high inter-individual variability in both δ13C and δ15N values; further analysis indicated negligible differences in the isotopic niche of adult males and females. Conversely, δ15N values were significantly related to the size of the specimens, ultimately suggesting an ontogenetic dietary shift. This study represents the first attempt to characterize the trophic habits of the blue swimming crab in the context of an invaded food web and may contribute to the implementation of long-term management strategies of control and mitigation of its ecological impact.

The Blue Swimming Crab Portunus segnis in the Mediterranean Sea: Invasion Paths, Impacts and Management Measures.

Simple SummaryThe blue swimming crab Portunus segnis is native to the western Indian Ocean, including the Red Sea and the Persian Gulf. It entered the Mediterranean Sea through the Suez Canal at the end of the 19th century and has colonized most of the eastern Mediterranean coasts, becoming an invasive species. This study describes the distribution, aggregation patterns, and spatial structure of this species in the Mediterranean Sea through a series of ecological indicators. The results indicated a long phase of establishment and a recent, rapid expansion phase. Several settlement areas, where the species continues to be reported, were found. Since 2015 P. segnis has shown a conspicuous presence in Tunisia from where it is spreading northward and eastward. The study provides an insight on the impact of P. segnis on biodiversity and ecosystem services and proposes a series of desirable management actions to mitigate the expansion of its population. Invasive alien species represent one of the main environmental emergencies and are considered by the scientific community as being among the leading causes of biodiversity loss on a global scale. Therefore, detecting their pathways, hotspot areas and invasion trends becomes extremely important also for management purposes. A systematic review on presence of Portunus segnis in the Suez Canal and Mediterranean Sea was carried out in order to study the invasion paths from its entry from the Red Sea into the Suez Canal (1886) until recently (2021) through ecological indicators elaborated with GIS spatial–temporal statistics. Arrival, establishment and expansion phases and areas of P. segnis in the Mediterranean were identified. Settlement areas were detected along the Suez Canal as well as in the Levantine Sea, western Ionian Sea and Tunisian plateau ecoregions. Since 2015 a persistent area has formed in Tunisia from where the species is spreading northward and eastward. The study provides an insight on the impact of P. segnis on biodiversity and ecosystem services and proposes a series of desirable management actions to mitigate the expansion of its population. Following the 8Rs model that introduces the rules to mitigate non–indigenous species pollution, six of them (Recognize, Reduce, Replace, Reuse, Remove, and Regulate) have been identified as applicable and are discussed.

Extraction and characterization of chitin, chitosan, and protein hydrolysate from the invasive Pacific blue crab, Portunus segnis (Forskål, 1775) having potential biological activities.

The diversity of marine biomasses is a set of exploitable and renewable resources with application in several sectors. In this context, a co-culture based on three protease-producing bacterial isolates, namely Aeribacillus pallidus VP3, Lysinibacillus fusiformis C250R, and Anoxybacillus kamchatkensis M1V strains, was carried out in a medium based on the blue swimming crab Portunus segnis bio-waste. Proteases production was optimized using a central composite design (CCD). The highest level of proteases production obtained was 8,809 U/mL in a medium comprising 75g/L of Portunus segnis by-product powder (Pspp). The biological value of Pspp and its obtained derivatives were evidenced via accredited protocols. The recovered protein hydrolysate (PHyd) was found to be active towards radical scavenging power and against angiotensin I-converting enzyme (ACE). The blue crab chitin (BC) extraction efficiency was achieved with a yield of 32%. Afterwards, chitosan was prepared through chitin N-deacetylation with a yield of 52%, leading to an acetylation degree (AD) of 19% and solubility of 90%. In addition, chitosan is found to be active against the growth of all pathogenic bacteria tested.

Reproductive biology of the blue swimming crab Portunus segnis (Forskål, 1775) (Brachyura: Portunidae) in the Gulf of Gabes (southeastern Tunisia, central Mediterranean Sea)

The blue swimming crab Portunus segnis (Forskål, 1775) (family Portunidae) is one of the earliest Lessepsian invaders of the Mediterranean Sea and has been recorded for several decades in various Mediterranean areas. However, its presence on the southeastern Tunisian coast is very recent. This study describes the reproductive biology of the species in the Gulf of Gabes, including sex ratio, ovarian maturation, size at sexual maturity, spawning season and fecundity. Samples for biological investigation were collected from the commercial catches of trawlers and artisanal fishing units, from January to December in 2018. A total of 2 762 specimens, ranging from 19 to 158 mm carapace width (CW) and 0.638 to 356.109 g body weight (BW), were analysed. Females outnumbered males by 1.3 to 1 (1 581 vs 1 181 individuals). Sexual maturity was classified into five stages for females and three stages for males, based on visual observation of the colour and shape of the gonads. Spawning occurred three times during the year, with the first peak in May, the second in July, and the third—the most intensive peak—in October–November. Size at sexual maturity was 93.1 mm CW for males, and 93.6 mm CW for females. Females carried 142 242–2 640 080 eggs on their abdomen, with a positive linear relationship between fecundity and CW. The data presented in this study should be useful not only to detect variations in the reproductive cycle of P. segnis between regions but also to ensure sustainable management of the new fishery for the species in Tunisian waters.

Distribution, abundance, and life history traits of the blue swimming crab Portunus segnis (Forskål, 1775) in the Saudi waters of the Arabian Gulf

The blue swimming crab, Portunus segnis (Forskål, 1775), formerly known as P. pelagicus (Linnaeus, 1758) has become a major fishery resource in the Gulf. Yet, there are no regional studies on the stock population dynamics and life history processes of this species. Considering the extreme oceanographic features of the Gulf (high salinity and high temperature variations), which is hypothesized to cause fast growth of P. segnis, a study was conducted to determine the abundance/biomass distribution of its stocks, growth rates, and sexual maturation in the territorial Saudi waters in the Arabian Gulf. The study was based on trawling surveys, landing sites monitoring, and records of fisheries catch and efforts and juvenile habitat surveys. The spatial distribution patterns supported by generalized linear model indicated the occurrence of P. segnis in the nearshore shallow waters, and its absence from the offshore deeper waters, attributed to the variability of environmental conditions including salinity, temperature, and trophic resources. Manifa, one of the productive areas in the northern Saudi waters of the Gulf, had high abundance of the crab. In agreement with the hypothesis, the growth rate of the Saudi P. segnis was found to be the higher (2.12 K year −1) compared to other parts of the Gulf (1.1–1.7 K year −1) or other sea areas of tropical regions (0.95–1.68 K year −1). The study shows that P. segnis can spawn throughout the year, with at least three peaks: winter, late spring–early summer, and autumn. The L50% record obtained in this study with females (127 mm) and males (125 mm) are larger than those reported with the same species from other parts of the Gulf (113 mm) or with other congeneric blue species crabs reported from other tropical regions (61–113 mm). The present study provided basic data to develop a management strategy for the fishery of P. segnis in the region.

Morphometric and genetic characterizations of blue swimming crab Portunus segnis, (Forskal, 1775) along the Iranian coasts of the Persian Gulf and Oman Sea

Portunid crabs form the basis of important fisheries in many parts of the world, however, their population biology is poorly understood. The more than 90 species of the Portunidae are widely distributed in global oceans often with indistinct boundaries among species, especially in the Indian Ocean. To clarify the species occurrence and population genetic structure of Portunus pelagicus and Portunus segnis in Iranian waters, crab specimens were collected from four sites along the Iranian coast of the Persian Gulf and Oman Sea. For a subset of 40 sampled crabs, the Cytochrome C Oxidase subunit 1 (COI) was sequenced and compared among the four sites. This analysis identified P. segnis as the predominant species (39 out of 40 sequenced samples) with the infrequent occurrence of P. pelagicus (one out of 40 sampled). Genetic diversity analysis for P. segnis samples identified high to moderate haplotype (0.98) and nucleotide (0.04) diversities. Analysis of molecular variance (AMOVA) (ΦST=0.09629 P = 0.00673) revealed significant genetic differentiation between two sampling sites inside the Persian Gulf, at Chabahar and Qeshm which are 500 km apart. Comparisons of the variation in the carapace morphometrics of 104 male P. segnis among sites using canonical variate analysis showed significant differences among the four sampling sites (P < 0.0001). Overall, the results revealed a high degree of morphological and genetic heterogeneity in P. segnis over relatively small spatial scales in this region of the Indian Ocean. The morphological variability of this species is such that it masked the sympatric presence of the species, P. pelagicus. It is likely that other cryptic portunid congeners will be identified in other Indo-Pacific regions given the high level of genetic variability that has been previously described for P. pelagicus from this region.

Allometry, condition factor and growth of the swimming blue crab Portunus segnis in the Gulf of Gabes, Southeastern Tunisia (Central Mediterranean)

The blue swimming crab Portunus segnis (Forskål, 1775) is one of the earliest Lessepsian invaders of the Mediterranean Sea, and is recorded since decades in various areas of the Mediterranean. Its presence in the southeastern Tunisian coasts (Gulf of Gabes) is, however, very recent. Allometry, condition factor and growth of P. segnis were studied along the Gulf of Gabes coasts. Sampling was performed by artisanal fishing gears as well as trawl net during a one-year period (October 2015 to September 2016) as processed 4971 crabs were collected. The crab carapace width (CW) ranged from 45 to 168 mm for males and 50 to 159 mm for females. The crab carapace length (CL) was 22.02-89.20 mm and 38.70-85.28 mm, respectively for males and females. The carapace width-carapace length, carapace width- front, carapace width-carapace height and carapace width-weight relationships were studied in separate sexes of crab. The covariance analysis indicates a significant difference between the two sexes with respect to the carapace width-carapace length and the carapace width-weight relationships. The condition factor ranged between 0.0042 and 0.0118 with a mean of 0.0078. The condition factor decreased with increasing crab size. The Von Bertalanffy growth parameters CW∞, K and t0 were estimated on the basis of Length-frequency modal progression analysis methods. The mean values of L∞ (mm), K (year-1) and t0 would be, respectively, 206.48 mm, 1.34 and -0.130 for males; 183.89 mm, 1.42 and -0.127 for females and, 190.60 mm, 1.02 and -0.177 for combined sexes.

Baseline assessment of heavy metals content and trophic position of the invasive blue swimming crab Portunus segnis (Forskål, 1775) in the Gulf of Gabès (Tunisia)

This study provides a baseline assessment of cadmium, copper, iron, manganese, lead, and zinc concentrations in muscles, gills, and exoskeleton of the Lessepsian blue swimming crab Portunus segnis captured in the Gulf of Gabès (Southern Mediterranean Sea, Tunisia) in November 2015. Furthermore, the species' trophic position is estimated using CN stable isotope analysis. The exoskeleton showed the lowest metal contents; in soft tissues, the essential Cu, Fe, and Zn and the non-essential Cd, Mn, and Pb showed the highest and lowest concentrations, respectively. The crab was characterized by a trophic position of 3.32, confirming its carnivorous trophic habits. Compared with literature data on invertebrate and fish species from the same area, Cd and Pb resulted remarkably low in the crab's soft tissues, while a food web-scale dilution effect was indicated. The need of a comprehensive assessment of the ecological impact of Portunus segnis in invaded Mediterranean waters is discussed.

Feeding habits of blue swimming crab Portunus segnis (Forskal, 1775) in the northern coastal waters of Iran

The study of food and feeding habits of crab has manifold importance in fishery sciences. The blue swimming crab Portunus segnis is an opportunistic predator and the diet of which depends on local availability of food items. The distribution and biological aspects of crabs are largely dependent on the availability of preferred prey organisms. Feeding habits of the blue swimming crab, P. segnis were studied in the northern Persian Gulf by trawl nets during the period from May 2010 to April 2012. The stomach contents of 1722 crabs, ranging from 36 to 175 mm carapace width, were analyzed. The stomach contents appeared to consist of mainly large quantities crustaceans, fish and molluscs, also small quantities of unidentifiable matter and debris. Based on the major food groups were observed in different season, the crustaceans was the most dominant in summer (56 %) and the fish items and Mollusca were the most dominant in autumn (67 %) and winter (45 %) respectively. In Juvenile and sub adult crabs, crustaceans constituted the dominant food source and these were present in 56.7 % and 45.1 % respectively. In the adult groups and larger size groups, fish were the principal food item and these were present in 44.5 % and 53.5 % respectively, of the stomachs analyzed. There were no difference observed in the quantity of the food consumed in both sexes and also significant differences observed in the preference for food items in the different size groups. The crabs without barnacle comparatively voracious with barnacle-carrying crabs. Their diet also increased with increasing ovary stages while that the percentage of empty stomachs in ovigerous females was higher than non-ovigerous females. The C.V. index varied significantly in both sex that was ranged between 6.9- 56.0 % and 16.5- 48.0 % for male and female, respectively. This study shows that, despite the diversity in blue crab diets and feeding habits, there are carnivores with a preference for animal food and the behavior of active predators of sessile and slow-moving macro-invertebrates. It is suggested that a major reduction in availability of one prey group would not have a major effect on the crab population.

Bioaccumulation of polychlorinated biphenyl (PCB), polycyclic aromatic hydrocarbon (PAH), mercury, methyl mercury, and arsenic in blue crab Portunus segnis from Persian Gulf.

Bioaccumulation of polychlorinated biphenyl (PCB), polycyclic aromatic hydrocarbon (PAH), mercury (Hg), methyl mercury (MMHg), and arsenic (As) in the hepatopancreas and muscle of blue swimming crab Portunus segnis from Bushehr shore, north Part of Persian Gulf, were investigated. In addition, the relationships between crab size (carapace width) and PCBs, PAH, Hg, MMHg, and As levels in tissues were investigated by linear regression analysis. There were significant correlation between pollutants levels and crab size which were positive. The pollutants' concentrations were highest in hepatopancreas whereas lowest in the muscle of all crab species. The mean concentrations were 0.51ngg(-1)PCB 16, 0.64ngg(-1) PCB 99, 1.2μgg(-1) Hg, 0.81μgg(-1) MMHg, and 0.14μgg(-1) As. Also, mean concentrations of different PAHs were 0.31ngg(-1) Acenaphthylene, 0.51ngg(-1) Acenaphthene, and 0.71ngg(-1) Anthracene. Comparison between male and female indicated that the average PCBs, PAH, Hg, MMHg, and As concentrations in tissues of male crab were found to be significantly higher than those found in the female crab.

Condition factor and carapace width versus wet weight relationship in the blue swimming crab Portunus segnis

The size-weight relationship of a species allows for estimating the expected weight based on size. The present contribution aims at evaluating the body weight vs. carapace width relationship and the condition factor of the blue swimming crab Portunus segnis. These characteristics were analyzed for each sex using specimens collected monthly from April 2012 through to March 2013, at the Persian Gulf (Hormozgan Province, Iran). The size of each specimen was measured (carapace width) and weighed (total body wet weight). A total of 302 individuals of P. segnis were analyzed. The body weight-carapace width relationship indicated positive allometric growth in males and isometric growth in females. Body weight was higher in males than females of equivalent carapace width, and the means for condition factors were always higher in females than in males, due to the heavier gonads in the former, an expected pattern for many crabs. In both sexes, the lowest condition factor was detected in winter with an ascending trend in the next seasons. The oscillation in condition factor throughout the sampling year was more prominent in females and related to the reproductive cycle. The information reinforces data to define fishing closed seasons for this portunid that is used in many places in the world.

Study on PCB 101, PCB 153, mercury and methyl mercury content in blue crab Portunus Pelagicus from Khuzestan shore (Persian Gulf)

Distribution of polychlorinated biphenyl (PCB 101, PCB 153), Mercury (Hg) and methyl mercury (MMHg) in muscle, gill and hepatopancreas of blue swimming crab Portunus segnis from Persian Gulf were investigated. In addition, the relationships between crab size (carapace width) and PCBs, Hg, MMHg levels in tissues were investigated by linear regression analysis. There were significant differences in crab PCB 101, PCB 153, Hg and MMHg concentrations were detected between different tissues (ANOVA, P<0.05). The pollutants concentrations were highest in hepatopancreas whereas lowest in the muscle of all crab species. The recorded mean concentrations were 0.485 μg g−1 PCB 101, 1.89 μg g−1 PCB 0.463, 0.815 μg g−1 Hg and 0.471 μg g−1 MMHg. The results showed that significant relationships between PCB and Hg-MMHg levels and crab size were positive. Comparison between male and female indicated that the average PCBs and Hg-MMHg concentrations in tissues of male crab were found to be significantly higher than those found in the female crab.

Size at Maturity, Sex Ratio and Variant Morphometrics of Blue Swimming Crab Portunus segnis (Forskal, 1775) from Boushehr Coast (Persian Gulf)

Size at maturity, sex ratio and variant morphometrics of blue swimming crab Portunus segnis was studied for one year along the Persian Gulf coasts, Iran. Sex ratio during a year of study was M:F=0.92:1 which should be the relative frequency of females. Male blue crabs have a V-shaped abdomen and female have an abdomen broad and rounded. The carapace width/length- weight relationship was studied in both sexes of crab. The allometric relationships between the characters of this set suggest that most relationships are positive and highly significant. An analysis of covariance indicates that there is a significant difference between sexes with respect to the carapace width-weight relationship. The crab’s carapace widths ranged were from 75 to175 mm for males and 70 to170 mm for females. The crab’s carapace lengths were from 35 to 80 mm for male and 30 to 80 mm for female. The results of this study show that at the same size, weight and the parameters of carapace length and carapace width male of Portunus segnis are higher than females in Persian Gulf coasts.