Friday, August 7, 2009

PS 76-11: Impacts of land use on benthic invertebrate diversity in the East River in China

Yixin Zhang1, David Dudgeon2, Dongsheng Chen3, Wai Thoe2, Zhaoyin Wang4, and Joseph H. W. Lee2. (1) Texas State University at San Marcos, (2) The University of Hong Kong, (3) Institute of Water Resources and Hydropower Research, (4) Tsinghua University


Land use change and aquatic habitat degradation have important implications for lotic biodiversity because these anthropogenic disturbances pose severe threats to river ecosystems.  This is evident in the Pearl River Delta, southern China, where rapid population growth, economic development and urbanization have been associated with changes to streams and rivers caused by pollution, sand dredging, dam construction, and over-fishing.  However, there are limited data on the impacts of these threats to benthic invertebrate diversity.  We examined human impacts on the East River (Dong Jiang) tributary of the Pearl River, a major source of water supply for Hong Kong and Guangdong Province in China.  We hypothesized that increased disturbance intensity in river channel would significantly reduce taxon richness and affect the structure of benthic communities. We used total impervious area (TIA, % of total urban and rural areas within a catchment) for measuring land-use disturbance at 11 sites along the East River. Benthic invertebrates were sampled at each site. Water Quality Index was calculated from 7 water-quality parameters to indicate water quality condition.


Forty-one insect families were collected.  At upstream sites with relatively low anthropogenic disturbance, taxon diversity was high (34 families); it declined downstream (26 families in the middle section), and decreased to a minimum (20 families) in the main channel of the lower course.  Ordination by principal components (PC) analysis separated the 11 study sites into 3 groups, in which PC 1, correlated with TIA, explained 51% of total variance, and PC 2, correlated with nutrients, explained 20% of total variance.  Modeling by partial least squares projection onto latent structures showed that taxon diversity was strongly, negatively influenced by TIA and pollution.  Multi-response permutation procedure tests showed highly significant differences in richness and relative abundance of different taxa among site groups.  Richness and total macroinvertebrate abundance were positively correlated with a composite Water Quality Index.  This study confirms the impact of human activities on the ecological integrity of the East River, showing it is associated with a loss of biodiversity and probable decline in ecosystem services.