The common method of using lobster-pot catch data for investigating relative abundance, sex and size distribution has serious disadvantages. This study estimates relative abundance and size of the European lobster Homarus gammarus and the brown crab Cancer pagurus using scuba diving techniques. The study areas were the Kåvra lobster reserve (Kåvra) on the Swedish west coast and three very different nearby areas where fishing for crustaceans is allowed: Gullmarsfjorden; the archipelago; and the offshore area. A total of 167 lobsters and 337 brown crabs were observed during 33 scuba dives (each 30 minutes long) in 2018-2019. The estimated mean abundance of lobsters was three to fifteen times as high at Kåvra in comparison with the other three areas (all exact showing that the statistical populations were distinct in comparison with Kåvra; Wilcoxon-Mann-Whitney Test). Dive sites in the outer part of the offshore area had the lowest abundance of lobsters although they had seemingly good lobster habitats and low fishing intensity. Large lobsters with a carapace length of ⩾15 cm were found only at Kåvra where they made up 24% of the lobsters. The proportion of large lobsters inside Kåvra continues to increase after 30 years of protection. Together, this emphasizes the impact of fishing on lobster abundance and size distribution, and indicates that limited recruitment and migration might possibly affect offshore lobster “sub populations”. Kåvra was the only area where the abundance of lobsters exceeded the abundance of brown crabs (). However, the abundance of brown crabs at Kåvra was as low as in Gullmarsfjorden () where fishing for crabs is allowed. Possible complex lobster/brown crab interactions together with other factors that might explain the low abundance of the protected brown crab at Kåvra, need to be investigated further.
Heat shock proteins play an important role in maintaining normal cell function and overcoming stress conditions in organisms. Expression of the heat shock protein 70 gene (hsp70) at different stages of embryos and larvae of the giant freshwater prawn, Macrobrachium rosenbergii (De Man, 1879) was analysed using quantitative real-time polymerase chain reaction. Expression of hsp70 was first detected in embryos of 5.5 days old; the expression levels gradually increased during the course of embryonic development, reaching their maximum at the stage prior to hatching. Whereas the expression levels were high in newly hatched larvae, they lowered subsequently before increasing to their maximum after 20 days post-hatch. Moreover, induction of hsp70 expression in 5.5 days old embryos and newly hatched larvae by two xenobiotics, 4-nonylphenol (4-NP) and chlorpyrifos (CPF) was also investigated. The results showed that both 4-NP and CPF caused similar patterns of hsp70 expression changes. Embryos exposed to 4-NP or CPF for 24 h increased the hsp70 expression levels with increasing concentrations of 4-NP or CPF. Prolonged exposure for 96 h induced higher levels of responses. The larvae were more sensitive than the embryos to both 4-NP and CPF challenges, by responding to lower concentrations of stressors and producing higher expression levels. The study suggests that hsp70 plays an active role during early life stages of M. rosenbergii, indicating the presence of mechanisms to overcome stress caused by development or by external stressors at these stages.
Pentias thompsoni Collinge, 1916 is recorded for the first time from China. The male specimen is described firstly, including the micromorphological characters of penes and appendix masculina. The partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) of the species are also provided for a molecular characterization.
Two species of the family Majidae, Sakaija japonica (Rathbun, 1932) and Schizophroida simodaensis Sakai, 1933, are herein newly reported from Korean waters. These are also the first records of Sakaija Ng & Richer de Forges, 2015 and Schizophroida Griffin & Tranter, 1986 in Korea. There are currently 14 majoid species from nine genera in Korea. Herein, diagnoses of Sakaija japonica and Schizophroida simodaensis are provided together with illustrations.
A new species of telescope shrimp, Ogyrides sindibadi sp. nov. is described from Kuwait. The new species is morphologically similar to O. striaticauda Kemp, 1915, originally described from Chilka Lake (India), but can be distinguished by the shape of the scaphocerite, the much longer dactylus of the third pereiopod, as well as the shape of the distal margin of the telson.
Between 2014 and 2019, four specimens of Paragalene longicrura (Nardo, 1868) were accidentally caught in the Adriatic Sea near Pula (Istrian Peninsula, Croatia). These are the first records of the little known species from the northern Adriatic Sea, as well as the northernmost occurrence over its global distribution. We have collected all documented occurrences from the literature since the description of the crab, resulting in a total number of 85 known specimens. Upon comparing the habitat type and depth distribution of our specimens with the recorded sightings, water temperature, and not depth, appeared to be the major determining factor for vertical distribution. Twenty-nine specimens have been detected in museum inventories, but not included in published articles. Our discoveries increased the number of known Adriatic specimens from 7 to 11. For the first time, we compiled all available carapace measurements to get an impression of the size range of the species.
Crustaceans usually autotomize their limbs in response to physical or physiological threats. In this study, the short term effects of different degrees of autotomy on immune function and disease resistance of Portunus trituberculatus were studied by autotomizing one limb (mild autotomy) or four limbs (severe autotomy). The results indicate that the total haemocyte count (THC) of these crabs showed a tendency to decrease rapidly at first, then increase, and then decrease after mild autotomy and severe autotomy, but the THC changes for individuals with mild autotomy lagged relatively behind. The haemocyte compositions of the crabs also changed greatly after limb autotomy; especially in the severe autotomy group, the proportion of large granular cells and non-granular cells increased significantly within 0.5 h and 2 h after treatment, and the proportion of small particle cells clearly decreased. From the changes in related immune enzyme activities, the effect of autotomy on the activity of haemolymph superoxide dismutase (SOD) in P. trituberculatus was notably low, but had a greater influence on the activities of phenoloxidase (PO), lysozyme (LZM), acid phosphatase (ACP) and alkaline phosphatase (AKP). Among these activities, PO activity decreased significantly within 1 h after treatment and then gradually recovered, LZM activity began to rise continuously within 4 h of autotomy, and both ACP and AKP activity increased immediately after treatment and then gradually decreased. Compared with the individuals with severe autotomy, the haemolymph immunoenzymatic activity of the mild autotomy crabs was slight and slower. In addition, limb autotomy directly affects the disease resistance of P. trituberculatus, especially for the case of severe autotomy, i.e., the resistance of P. trituberculatus to disease is significantly weakened, and the probability of death greatly increases. On the whole, P. trituberculatus could respond to the short term negative effects of limb autotomy by corresponding physiological regulation mechanisms, but the disease resistance was still reduced. This study showed that the self-regulation ability of P. trituberculatus in response to limb autotomy was limited, especially in the case of severe autotomy.
Double whey acidic protein domain-containing proteins (DWDs) or secretory leukocyte protease inhibitor (SLPI)-like proteins, have been identified in many species of Crustacea. The PvDWD1 from Penaeus vannamei was the first SLPI-like protein identified in a crustacean. Herein, we report that the expression of PvDWD1 was up-regulated at 6 h after acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio parahaemolyticus (VPAHPND) challenge. Similarly, after a different stress other than bacterial infection, the chronic non-lethal heat shock (NLHS) induction, the expression of the PvDWD1 gene was increased at 6 and 24 h after chronic NLHS treatment. The recombinant PvDWD1 (rPvDWD1) protein was over-expressed and tested for its deleterious activity against the bacteria. The rPvDWD1 protein exhibited growth inhibitory activity against Bacillus megaterium and VPAHPND. Moreover, the rPvDWD1 protein possessed an antiproteinase activity against the secreted proteinases from Bacillus subtilis and VPAHPND. The PvDWD1 perhaps functions in shrimp immunity through antimicrobial and antiproteinase properties.
The freshwater crab Aegla expansa Jara, 1992 (Aeglidae) is endemic to Chile and has a geographical distribution restricted to one stream in the locality of Hualqui (37°S), Concepción Province, Chile. A chromosome number is here described for somatic cells of A. expansa. The chromosomes are large in number and small in size (<2 μm). These cytogenetic data are the first reported for a species of the genus Aegla.
In tropical countries, a large number of finfish species and invertebrates are captured as by-catch, including several species of crustaceans, due to the low selectivity of the fishing methods. By-catch presents and optimal opportunity to study populations of crustaceans. Here, the goal was to determine the community structure, specifically through the size structure, as well as the average sizes at first maturity of crustacean species present in the shrimp by-catch caught aboard a fishing vessel operating in the Mexican Pacific, from Sinaloa to Guerrero, Mexico. From the 18 crustaceans found in this study, the crabs Euphylax robustus and Achelous asper were the dominant species, whereas four species were considered casual (i.e., not frequent). Interestingly, more than 40% of the organisms analysed were in the juvenile stage, and 19% were ovigerous females. The results demonstrate the negative impact of the low selectivity of shrimp trawls on the communities of species of Crustacea.