| Chinese mitten crab (Eriocheir sinensis) as an important aquaculture species are farmed in most parts of China. Because the geographical origin differences of crabs result in different qualities and prices, fake products and counterfeit brands can be often found to replace the highly esteemed crabs in markets. In the present study, characteristics of morphology and element accumulation were studied comparatively with E. sinensis from different waters (Panjin, Hongze Lake, Xinghua and Liangzi Lake) in the Liaohe river system and the Yangtze River system. A truss network of 16 distance measurements were measured within each individual in morphology study. At the same time, an Agilent 7500ce inductively coupled plasma mass spectrometry (ICP-MS) was used to determinate the element concentration in the third pereiopod of the Chinese mitten crabs from the three lakes for element accumulation study. The distribution and concentration of major element calcium (Ca), magnesium (Mg) and phosphorus (P) in the exoskeleton of the crabs were measured using a JEOL 8100 electron probe microanalysis (EPMA). Furthermore, the patterns of morphological parameters and the element environment fingerprint were further investigated by discriminant analysis in order to assesse the validation of the approachs in the present study for the possible geographical origin identification of Chinese mitten crabs from different water regions (i.e., geographical origin). The present study hopes to provide the theoretical basis and technical information for future application of geographical origin identification on broad fishery products in China.1. Morphological character study:One-way ANOVA analysis results showed that samples of the crabs in four water regions of same/different river systems were significantly different (P<0.05) among 16 morphological parameters, and the significantly difference (P<0.05) could be also found in the crabs from the three water regions in the same river system among the 10 morphological parameters (e.g., E/A, Q/A, H/A, I/A, and J/A, and K/A, and L/A, N/A, P/A, F/A, etc.). Cluster analysis showed samples from Liangzi Lake were the nearest to those from Hongze Lake and gathered into a category. Samples from Xinghua presented a separate cluster, and those from Panjin showed another separate cluster, which were far from the cluster of the crabs from the aforementioned three water regions. Top five main ingredients were obtained with Principal Components analysis (PCA), and the variance contribution rate were 22.484%,16.679%,13.833%,11.391% and 6.757%, cumulative variance contribution rate,71.155%, respectively. It shows that very few independent producers of factors not easily summed up in 4 groups of the Crabs morphological differences. Discriminant analysis of Chinese mitten crabs from four water regions awarded a correct rate of 100%. Therefore, the usage of discriminant analysis on morphological characteristics can possibly distinguish the crabs from four water regions, which may be contributed not only by with natural environment, but also by the auqculture envuronment.2. Element environment fingeprint:Elemental fingerprints of Na, Mg, Al, K, Ca, Mn, Fe, Cu, Zn, Sr, Ba, and T1 were studied comparatively with the third pereiopods of Chinese mitten crabs from four origin waters, i.e. The results suggested that the crabs between the dual origin waters presented significant differences of concentration for Na, Mg, Al, K, Mn, Fe, Cu, Sr, Ba, and T1 (P<0.01). Principal components analysis suggested that Fe, Mn, Al, Na, Cu, Ba, Zn and K related more to the crabs from Panjin, while Mg, Sr, T1 related more to those form Hongze Lake, respectively. In contrast, Ca, Mg, Sr, T1, K, Zn related more to crabs from Xinghua, while Fe, Mn, Al, Na, Cu, Ba related more to those from Liangzi Lake, respectively. Moreover, the origin of the crabs from the four different waters could be identified consistently by discriminant analysis of the elemental fingerprints with a 100% accuracy rate. The present study further demonstrated that the approach of the elemental fingerprints in the third pereiopod of E. sinensis is potentially valid for geographical origin identification of Chinese mitten crabs from the waters of either the same river or different river systems.3. Element microchemistry analysis of exoskeleton:the exoskeleton of E. sinensis was found comprising four layers, i.e., the epidermis, the exocuticle, the endocuticle and the membraneous layer. Mapping analysis of Ca, Mg, and P in the exoskeleton showed a tendency of the highest in Ca content, the moderate in P content, and the lowest in Mg content. The highest concentrations of Ca were in the epidermis, those in the exocuticle markedly decline, and those in the endocuticle were more uniform, but there was a decline trend of Ca content in the location close to the membranous layer. Mg distributions were similar to those of Ca. There was a clear downward trend outer the exocuticle, but distributed evenly within the endocuticle. P was mainly existed at the front of the exocuticle and the end of the endocuticle. Element line transect analysis of four samples of the crab exoskeletons in the epidermal laye suggested that Mg were very significant differences. Discriminant analysis showed that the discriminant correct rate of crabs from four water regions of Panjin and the Hongze Lake, Xinghua, Liangzi Lake were 40%,40%, and 60%, respectively, with combined rate of 55%. Due to the low distinguish rate, element line transect analysis seemed to not be enough to distinguish the crabs from different water habitats, but element mapping analysis has the potential for discriminant analysis because of the different elemental accumulation patterns of the crabs from different water regions. |
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