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EN
In this study, the effects of different feeds on fatty acid composition in the Chinese mitten crab (Eriocheir sinensis) were investigated. The fatty acid composition in the Chinese mitten crab was significantly correlated with the type of feed source provided. Differences between the feed groups pertained mainly five fatty acids: oleic acid, linoleic acid, palmitic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The content of EPA and DHA was higher in the group of frozen trash fish than in the group of formulated feed. On the other hand, the content of oleic acid, linoleic acid and palmitic acid was higher in the formulated feed group than in the frozen trash fish group. There were significant differences in the nutritional value of the Chinese mitten crab reared under different feed sources, i.e. Chinese mitten crabs reared with the frozen trash fish feed were larger than those reared with the formulated feed, especially as regards the ω-3/ω-6 PUFA ratio and essential fatty acid levels.
EN
The feeding ecology of the Chinese mitten crab Eriocheir sinensis was studied by analyzing the stomach fullness and its content with regard to sex, size and brackish water habitats occurring on the coast of the Baltic Sea (Gulf of Gdańsk and Vistula Lagoon, Poland) and the Atlantic (Tagus Estuary, Portugal). The presented results show that neither the site, sex (except the Gulf of Gdańsk) nor the size of an individual had a significant (p > 0.05) effect on the stomach fullness of E. sinensis. However, the type of food consumed was significantly (p < 0.05) correlated with the inhabited locality. The stomachs of crabs contained the remains of animal and plant origin, as well as detritus. The remains of animals (Bivalvia, Amphipoda, Gastropoda and Polychaeta) were more frequently found in the crabs from the Gulf of Gdańsk, while the remains of plants (Tracheophyta, Chlorophyta) were most often found in the stomachs of crabs from the Vistula Lagoon and the Tagus Estuary. Detritus was found only in the Gulf of Gdańsk and the Vistula Lagoon. Research indicates that the feeding ecology of omnivore E. sinensis is habitat specific, which should be taken into account when assessing the risk associated with this invasive species.
EN
We have quantified the relative growth of the merus and the propodus & carpus of walking legs of an adult of Eriocheir sinensis against the carapace width by fitting the major axis lines. Different lines have been fitted to data relative to male and female individuals. Slope and elevation tests have been performed to investigate sexual dimorphism. Isometry tests have been used to classify the relative growth of each part of the legs against the carapace width as isometric or allometric. All the slope tests have not rejected the null hypothesis of a common slope for the major axes fitted to male data and to female data. However, all the elevation tests have rejected the null hypothesis of a common elevation; so sexual dimorphism was detected for all measured leg parts. The isometry tests have rejected the null hypothesis of isometry only for the merus of the first (left and right) legs of male individuals. All the other isometry tests have not rejected the null hypothesis of isometry. So the relative growth of all the measured leg parts, but the merus of the first (left and right) legs of males, against the carapace width was isometric both for males and for females.
EN
A total of 379 individuals of Eriocheir sinensis (198 males and 181 females) were captured in the Odra estuary (Poland). The crabs were thawed and their carapace length (CL), the maximum carapace width (CW) and the maximum height (CH) were measured. Measurements were also taken on each claw, the claw length (CHL1, the right claw; CHL2, the left claw), the width (CHW1 and CHW2 for the right and the left claw, respectively), and the height (CHH1 and CHH2 for the right and the left claw). For each crab, the wet weight was measured for each of the following body components: the whole crab (CrWe), the carapace (CaWe), the right claw (WRC) and the left claw (WLC). For females, the relationship between CL and CW, CH and CW were isometric, and for all linear measures, the relationship with CW was positively allometric. For males only this first relationship was isometric, but others were positively allometric. The differences between relative growth parameters for males and females were statistically significant.
EN
Carapace length and width as well as condition were analysed in 2336 Chinese mitten crabs, Eriocheir sinensis, caught in 1999-2007 in the Odra River estuary (Poland). Their condition was assessed using the Fulton coefficient and the carapace width-individual weight relationship. September through November catches netted the highest number of crabs (83.60% of the total sample); males accounted for 53.56% of the crabs caught at that time. Males showed a significantly higher mean individual weight, significantly higher carapace width and length, and a higher Fulton coefficient than the females. The lowest mean individual weight, carapace width and length, and the highest condition coefficients were recorded in those crabs caught in 1999-2000. Later on, the mean carapace width and individual weight increased, and the increase was accompanied by a reduction in condition of the crabs. Causes of the differences are being sought in environmental changes taking place in the Odra estuary.
EN
Selected biological and morphometric characters of two populations of the non-indigenous Chinese mitten crab, one from the Szczecin Lagoon (SL) and the other from San Francisco Bay (SFB), both sampled in autumn, were analysed. The SL crabs showed a significantly higher individual weight, length and carapace width. Males accounted for 55% (87 individuals) of the 179 SL crabs, and 62.9% (90 individuals) of the SFB crabs. Statistical analysis of metric characters, expressed as a percentage of carapace width (X2), enabled four diagnostic characters to be identified: abdomen width (X11), carapace height (X3), left claw length (X7) and carapace length (X1). These jointly explain 71.75% of the differences between the SL and SFB crabs and are indicative of the distinctness of the populations.
EN
A newcomer to the Baltic Sea, the Chinese mitten crab is especially abundant in the Szczecin Lagoon (NW Poland), where it was first reported in 1927. Body weight, and carapace width and length, were studied in 647 individuals collected with fyke nets in the Szczecin Lagoon from 30 March-18 April 2001 and from 5-21 November 2001. 51.01 of the 543 autumn specimens were males, but only 30.97% of the 113 spring specimens were males. Body weight varied from 45.1 to 306.5 g, carapace length from 41.07 to 81.02 mm and carapace width from 46.68 to 88.85 mm. The autumn crabs were significantly heavier than the spring specimens.
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