Analysis Of Spatial Patterns Of Fish Diversity And Resources Of The Yangtze River Basin

Since the 1930s, Chinese ichthyologists have investigated the fish fauna in this area, anda large amount of information was published on the systematic, biogeographical, andecological aspects of the inland fishes. In spite of the numerous publications, synthesis andanalysis or assessment of fish biodiversity patterns are limited, which in turn limitsformulation of biodiversity conservation strategies. In this study, we attempt to synthesizeinformation on freshwater fish biodiversity in the Yangtze River basin. And we do aprelimary survey of slangids in the basin, and also explore molecular phylogeneticrelationships of salangid fishes (Osteichthyes: Osmeridae). First,we synthesized information on freshwater fish biodiversity in the Yangtze Riverbasin. We documented 361 species and subspecies that had been recorded and describedfrom the basin. Of these, 177 species are endemic. The basin is accustomed to be dividedinto three parts, i.e. the upper reaches, the middle reaches and the lower reaches. This studyindicated that the "three reaches"approach was not supported by fish distribution patterns.Hydrological alterations are perhaps the largest threat to fish biodiversity in the basin.Fishes in the upper reaches will be seriously affected by the construction of the ThreeGorges Dam and other dams, and action should be taken for priority conservation. The mostimmediate restoration need is reconnection of the Yangtze River with its lakes. The clusterof lakes in the Central Yangtze should be protected to maintain habitats for spawning,feeding and migration of migratory fishes. Our study indicates a need to identify areas ofhigh fish biodiversity and to selected nature reserves to mitigate the loss of fish biodiversityin the Yangtze River basin. Second,we document patterns of diversity, elevation range and body size thatcharacterize freshwater fish assemblages along the Yangtze River basin elevation gradient inChina. We used published data to compile the distribution, elevational ranges and body sizeof freshwater fishes in the Yangtze River basin. We assumed that a species occurrence at allelevational bands between its minimum and maximum elevation records. Maximum bodylength was used an estimate of body size. Correlation, regression, cluster and graphicalanalyses were used to explore the patterns of diversity, elevation range and body sizebetween 0 and 5200m elevational zones. The results showed that total species richnessdecreased slightly from 0-100m to 100-200m, increased from 100-200m to 400-500m, andthen tended to decrease rapidly with increasing elevation. Non-endemic species richness4长江流域鱼类生物多样性空间格局兼论银鱼的生物多样性与系统发育showed a significant monotonically decrease with increasing elevation (P<0.0001).Endemic species richness has two peaks, and exhibits major peak in 500-600m elevationzone, and minor peak in 1800-1900m elevation zone. The ratio of endemic species richnessto total species increased from 0-100m to 2300-2400m, and then decrease with increasingelevation. Area on a crude scale (500m interval) explained a significant amount of thevariation in species richness for total, endemic and non-endemic species. Cluster analysisrevealed 5 distinct assemblages along the basin elevation gradient. Species density of totalspecies and non-endemic species exhibits major peak in 500-1000m elevation zone, andminor peak in 3500-4000m elevation zone. For endemic species, exhibits major peak in1500-2000m elevation zone, and minor peak in 3500-4000m elevation zone. The elevationextent of species tended to increase with increasing elevation for total species, endemicspecies and non-endemic species, as Rapoport's rule predicts. The frequency distribution oflog maximum body length data displays the right-skewed pattern characteristic. Of the 6major families analyzed here, body size increase signi...