PHYSICAL HABITAT ASSESSMENT OF A REMAINING HIGH-BIODIVERSITY REACH OF THE UPPER YANGTZE RIVER, CHINA
Applied Ecology and Environmental Research
Zhang et al.: Physical habitat assessment of a remaining high-biodiversity reach -129 -APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 14(1): 129-143. Abstract. A scientific assessment on the physical habitat of a river in the only remaining free-flowing stretch in the Upper Yangtze, which has one of the world's highest fish diversity and is critically important. A field survey was tentatively conducted in this non-wadeable and data-limited reach (392 km river length, its 98.3% included the national
... cluded the national protected area) of the Upper Yangtze River using a 200 kHz echosounder and a 600 kHz Acoustic Doppler Current Profiler in 2011. The water depth, acoustic backscatter characteristics of river bottom (hardness and roughness), and flowing characteristics (depthaveraged velocity (DAV), Froude number (Fr), and Reynolds number (Re)), which are popular in describing the habitat preference of aquatic organisms, were determined to describe the river habitat properties. The K-means clustering method using parameters river thalweg depth, DAV, and Fr categorized the 392 river segments into three biological meaningful habitat types, pool, run and riffle, with occupied 5.4%, 30.1% and 64.5%, respectively. Thus, the pool was the most comparatively rare habitat type and should be carefully protected. This study provides a fast and efficient method for assessing the habitat characteristics of a non-wadeable and data-limited river, moreover, the results supply fundamental information for better national protected reach management.