The Chinese Sturgeon Habitat Landscape Pattern Change In The Yangtze Estuary And Its Habitat Suitability Assessment

Chinese sturgeon (acipenser sinensis Gray), Class Ⅰ endangered species in1988by chinese government, threatened animal listed in IUCN Red in1994, is one ofthe most primitive fish species all over the world about140million years ago andtypical anadromous species that presently only remains in the chinese coastal watersand mainstream of yangtze river. The yangtze estuary, with international importantwetlands and chinese sturgeon nature reserve, is not only the unique channel formature chinese sturgeon upriver reproductive migration and the juvenile downriverfattening, but also the most vulnerable, the inhabiting longest, the most concentratedand unique natural habitat of juvenile stage in the sturgeon life cycle. So this area isgreat significant to its survival. Nearly30years, Chinese sturgeon habitat in theyangtze river estuary gets more and more seriously disturbances, such as habitat loss,degradation and fragmentation, attributed to the water conservancy projects, ThreeGorges Dam, Gezhouba Dam, building in the yangtze river mainstream, as well as thetideland reclamation, environmental pollution, large wading engineering, bycatch, etc.It is so necessary to get down to Chinese sturgeon habitat suitability assessment in theyangtze estuary. So habitat suitability evaluation and its model development of GIStechnology have been accomplished after the habitat landscape pattern changeananlysis. The habitat model including habitat mapping, biodiversity calculation,habitat suitability index assessment and suitability areas calculation, can be run inArcgis9.3software and be able to find suitable region quickly for jourvnile sturgeongrowth. The results will provide a scientific reference for Chinese sturgeon speciesconservation and nature reserve construction management. Its main contents are asfollows:(1) The Yangtze estuary ecological environment change between August2001and August2006has been studied by landscape pattern index from landscape ecology. The results show that the ecological environment of the Yangtze estuary waters wasdisturbed significantly by human activity. The pollution of inorganic nitrogen andactivated phosphate were seriously, and their patches sensitivity were high fordisturbance and the diversity indices of patches declined; the predominant indicesgenerally increased as well as the concentration of suspended sediments attributed tohuman activity that dominated by major project during the5years. Fragmentationdegree indices of these patches, salinity, COD, suspended sediments, chlorophy a, hadrised; the diversity and fragmentation indices of phytoplankton, zooplankton andbenthos of the Yangtze estuary waters in2006remained at a high level.(2) Various ecological factors impacting Chinese sturgeon juvenile habitatselection had been statistical studies. Five habitat indices were selected by thequantification theory I and their most suitability scope were determined, thensuitability index analysis was used to do quantitative evaluation on the platform ofGeographical Information System (GIS). Suitability Index was verified by the CPUEof Chinese sturgeon from tidal nets monitor, water quality and biological data nearbythe monitoring station in Chongming Dongtan of the Yangtze River Estuary from theyear of2004to2010. At last, the data of the coastal water investigation of Shanghai insummer2006were evaluated. The study results demonstrated that the excellenthabitat area is142.38km2（0.75＜HSI≤1.0）, the good area is1312.98km2（0.5＜HSI≤0.75）, the fair area is2097.60km2（0.25＜HSI≤0.5） and the poor area forChinese sturgeon is2883.80km2（0＜HSI≤0.25）.these all determined by Habitatsuitability index，while the fair habitat area is comparative larger，it is6362.79km2（0.25＜HSI≤0.5）.(3) Custom scripting tools edited by python computer language were added intoarctoolbox of Arcgis9.3software. The habitat assessment model function wereaccomplished preliminarily after four modules, habitat mapping, biodiversitycalculation, habitat suitability index assessment and suitability areas calculation,created in the ModelBuilder platform.