Structure of endemic fish assemblages in the upper Yangtze River Basin

Abstract

This study focused on characterizing the endemic fish assemblages in the upper Yangtze River Basin and identifying the relative influences of catchment land-cover variables on observed fish patterns in order to suggest a conservation strategy. A model based on a self-organizing map was applied to determine endemic fish assemblages along the river network, based on presence/absence data for 124 endemic species. Five fish assemblages (Ia, Ib, IIa, IIb1, IIb2) were described. These assemblages varied significantly in terms of individual species patterns as well as species richness. Indicator species were identified for each class of community (0, 3, 9, 27, 0 species for cluster Ia, Ib, IIa, IIb1, IIb2, respectively). Structure of the endemic fish assemblages in the upper Yangtze River was highly correlated with local topographic and geomorphic characteristics. Simultaneously, the catchment land cover features also reflected out this endemic fish distribution structure. Among 18 land-cover types, alpine and sub-alpine meadow, together with farmland, were revealed to be the most important factors both in discriminating the endemic fish assemblages and in correlating species distributions by using discriminant analysis and co-inertia analysis. Finally, in order to preserve the rare and endemic fish in the upper Yangtze River, reserve networks, rather than a single national nature reserve, should be established.

Interannual variations of the fish assemblage in the transitional zone of the Three Gorges Reservoir: persistence and stability

“…Our results support the view that flow regime had a large impact on the fish assemblage. Human-induced threats related to hydroelectric development lead to the decreasement of endemic fish resources in the upper Yangtze River (He et al 2011). Fortunately, the endemic fishes in the upper reaches of the Yangtze River, such as C. guichenoti, R. ventralis, L. elongate, and R. cylindricus, continue to account for a certain proportion in the transitional zone.…”

Fish assemblages and diversity in three tributaries of the Irrawaddy River in China: changes, threats and conservation perspectives

“…Due to a lack of richness information from literature resources and uncontrolled sample sizes in different collections, only presence/absence data were used in this study. Despite the simplicity of presence/absence data, they provide reliable information for analyzing fish assemblage patterns (He et al, 2011). Some diversity indices that are robust under variable or uncontrolled sampling effort were chosen to reflect variation in the structure of the fish assemblages along different gradients.…”

Assessing fish distribution and threats to fish biodiversity in the Yangtze River Basin, China

“…Within the threats to habitat loss/degradation, damming and other hydraulic construction appeared to be the most significant threats. The construction of dams at cascades in the river and its tributaries has blocked the passage of migratory fish species, changed hydrological conditions, made their habitats fragmented, and brought about severe impacts on fish habitat and spawning environments (Dudgeon 2000;He et al 2011). Water pollution influences fish resources not only through the direct effects on fish survival, but also through negative impacts on various kinds of food organisms of fishes such as plankton and benthos, resulting in decreases in the abundance of natural fish stocks (Huang and Xie 1996;Ye 2007).…”

“…In contrast, slow growth rate, population fluctuation, and high juvenile mortality could be minor causes of fish endangerment. The endemic fish distribution in the upper reach is represented by complicated assemblages, which are highly correlated to the topographic and geomorphic characteristics of the upper basin (He et al 2011). Generally, these endemic species are well adapted to specific habitats with relatively small population size.…”

“…A conservation recommendation, according to which the habitats rich in endemic fishes should be considered as nature reserves, has been put forward (Liu and Cao 1992). In view of the different endemic fish assemblages (with multiple habitats and different fish compositions) in the upper Yangtze River, different reserves aimed at different conservation objectives should be set up to preserve fish biodiversity (He et al 2011). At present, there are three fish reserves, of which one is for the protection of rare and unique species in the upper reach at the national level, and two are for the protection of the Chinese sturgeon at the provincial level.…”