Diet And Morphological Differences Of Feeding Organs Among Five Culters In Changhu Lake

As the third largest lake in Hubei Province, Changhu Lake is situated at the juncture of Jingzhou City, Jingmen City and Qianjiang City. It locates in the upstream of "Four-Lake drainage area" in Hubei Province. Meanwhile, it is an important ecological function zone of Jianghan Plain in the middle- and downstream of Yangtze River.With 140 square kilometers water area and 310 kilometers coastline, it is always being called as "Hundred miles Changhu Lake". With abundant biodiversity, it is known as the important "gene pool" of aquatic plants and animals and wetland ecosystem in the middle- and downstream of Yangtze River basin. There are five Culters in Changhu Lake, Cultrichthys erythropterus, Culter alburnus, Culter dabryi dabryi, Culter mongolicus mongolicus, Culter oxycephaloides. The Culters resource of Changhu Lake mainly comes from the Yangtze River. Compared to the past, the current output of Culters in Changhu Lake has declined, but which is still as high as tens of thousands of kilograms every year. Therefore, Changhu Lake is a large Lake with various and high abundant Culters resources. In 2010, the Ministry of Agriculture formally approved the establishment of Culters Aquatic Germplasm Resources Reserves of Changhu Lake in order to protect the five Culters and other biological resources. Establishment of protected areas for the conservation and restoration of aquatic biodiversity and wetland ecosystems, to better play Changhu Lake aquatic germplasm resources, sustainable wetland ecosystem functions and regional economic development are of great practical significance.(1) Diet differences of five Culters in Changhu LakeAbout the composition of food, food consists Hemiculter leucisculus, Carassius auratus, Pseudorasbora parv, Abbottina rivulari, Rhodeus., Hypseleotris swinbonis, fish residues, shrimp, shrimp debris, insects, plants and other other food. Main food of Cultrichthys erythropterus, Culter alburnus, Culter dabryi dabryi, Culter mongolicus mongolicus are small fish and shrimp, but the kind of differences in the proportion of food intake. Food composition changes with the seasons change.Cultrichthys erythropterus feeding on fish more in the spring, summer, winter, in autumn feeding shrimp more. Culter alburnus in the spring and autumn feeding smaller appetite for Carassius auratus and Rhodeus., in autumn feeding a lot of food without Carassius auratus and Rhodeus. Other than winter feeding more single with Pseudorasbora parva. Culter dabryi dabryi main feeding Carassius auratus spring, summer mainly fed Hemiculter leucisculus, Carassius auratus, Pseudorasbora parva. In autumn feeding a lot of food except Carassius auratus and Rhodeus.,in winter feedingPseudorasbora parva and Hypseleotris swinbonis. Culter mongolicus mongolicus anniversary of a variety of food intake are more balanced, volatility is not only in winter feeding on Pseudorasbora parva more single and prominent. Composition of food of Culter oxycephaloides is not clear, but contains fish and shrimp.Feeding intensity of four Culters changes with seasons. The average stuff of four Culters is highest in summer and lowest in winter.’Cultrichthys erythropterus average full index lay highest in spring and lowest in winter. Culter alburnus and Culter dabryi dabryi and Culter mongolicus mongolicus lay the average full index Mongolian Culter are highest in spring and lowest in autumn, there may be short-term stop feeding the situation.Food niche and food overlapping calculations between four Culters Changhu Lake show food niche is very close, there is a significant overlap between food species, to serious overlapping, indicating that there is a serious competition for food among the four Culters.(2) Morphological variation of feeding organs of five Culters in Changhu LakeThe morphological variation of feeding organ of these five species was investigated by using multivariate statistical analysis methods. The results showed that there were significant differences in the morphological-traits of 11 feeding organs morphological traits (P<0.05).The maximum difference lay between Cultrichthys erythropterus and Culter mongolicus mongolicus,-with only the number of gill rakers having no significant difference. The minimal difference lay between Culter alburnus and Culter dabryi dabryi, with more than half characters having no significant difference. The discriminant functions of the five Culters were established based on 9 morphological characters. The total accuracy of discrimination was 86.64%.The principal component analysis yielded four principal components with a cumulative contribution ratio of 68.41%. A cluster analysis indicated that the morphological characters of Culter alburnus were most similar to Culter dabryi dabryi, and Culter mongolicus mongolicus similar to Culter oxycephaloides. The results suggest that there are differences and similarities between morphological variation of feeding organ five Culters and this variation has correlation and adaptation with diet composition.To make sure rational management and utilization of fishery resources, good protection of five Culters and other aquatic germplasm resources, peple need to make adjustments on the fishing structure, strengthen the management of fishery law on closed areas during closed season reinforce the management of fishing gear and methods. When necessary, measures must be taken to make artificial supplement. So that fishery resources of Changhu Lake would get better restoration and supplement, finally to achieve sustainable development.