Research On Method And Distribution Pattern Of Functional Diversity In Chinese Freshwater Fish Assemblages

With the rapid growth of world population and human economic activities, the biodiversity around the world is reducing beyond the imagination of people, which had greatly influenced the human’s ecosystem well-being depend on the biosphere. Currently, the function of community ecology has become an key way to solve ecological problems, community functional diversity research in China mainly concentrated on the microbial community and plant community, while the fish community research is almost blank. Fish resources in China was facing a serious threat, including habitat destruction, the deterioration of water quality, species invasions, disconnection between lake and river. Thus, we carried out a study of fish biodiversity to provide a novel theoretical basis and applications of fish resources protection. Firstly, we built a database of China’s inland waters of freshwater fish through researching the species information recorded in the database and ichthyology books, combining the authors’ wild fish survey records in recent years. Then, we tested the methods of functional diversity, which were measured by species functional traits(such as feeding, foraging strategy, size, movement, breeding and habitat) or by a set of morphological index of ecological significance and function. Finally, we studied the beta functional diversity of Cyprinidae fish community in Chinese tributaries, which was divided into taxonomic turnover(i.e. species replacement between communities) and nestedness-resultant components(i.e. those that reflect the difference in the number of species among communities). The main research results were concluded in the following aspects:(1)Species information recorded in the database and Chinese ichthyology showed that 1133 kinds of freshwater fish species was belong to 19 orders, 54 families, 286 genera. In the native species, Cyprinidae is the most abundant, containing 578 species, 51.02% of the total. Diversity of freshwater fish species showed a gradual decreasing trend from south to north, while showed a gradual increasing trend from west to east. And the distribution of species diversity in Cyprinidae has a similar trend.(2)Relationship between functional morphology and trophic position were examined in 116 species of freshwater fishes from the middle and lower Yangtze river flood plain. Results showed that the fish have specialized morphology corresponding with function only when it is herbivores and carnivores. For instance, herbivores have narrow gap. For carnivorous fish, specialized morphological characteristics were found i.e. ambushing predator exhibited fusiform, dorsal fin close to the head, larger eyes diameter, and pursuiting predator exhibited the streamlined body, a relatively smaller head region, dorsal and ventral fin near the tail. For omnivorous, there was no more evidence to prove that there are specialized external form.(3)quantitative relationship between morphology and trophic strategy and habitat use indicated that there was no significant correlation between external morphological and ecological traits in community levels. Morphology of fishes may be more inclined to deal with changes in hydrological conditions in floodplains. However, taxa with a relatively narrow taxonomic range show relationships between shape and functional traits, which suggests the need of further study of relationship between morphological and ecological functions.(4)By analyzing the functional diversity of fish communities in the China tributaries, we found that functional richness of Cyprinidae increased with the species richness. Taxonomic beta diversity in northern was higher than the southern, indicating high niche differentiation, in the southern region and low functional diversity due to harsh environmental constraints in northern region. High functional beta diversity is mainly due to the influence of the high nestedness-resultant, and high nestedness-resultant functional is mainly due to the low functional redundancy, indicating that the function redundancy between assemblages were low.