秦岭细鳞鲑栖息地环境特征研究

为研究秦岭细鳞鲑（Brachymystax lenok tsinlingensis）的栖息地环境选择偏好，对陕西陇县秦岭细鳞鲑国家级自然保护区和甘肃秦州珍稀水生野生动物国家级自然保护区内25个样点进行了鱼类采样和生境测量。共采集到130尾秦岭细鳞鲑样本，样点的平均分布密度为（0.10±0.07）尾/m，两个保护区内秦岭细鳞鲑的密度存在显著性差异（P < 0.05）。与秦岭细鳞鲑密度分布呈正相关的因子依次为坡度、跌水区密度、海拔、粗糙度、遮蔽度、底栖动物生物量和流速，与密度呈负相关的环境因子依次为河宽、水深和溶氧。冗余性分析（RDA）筛选了坡度、粗糙度、遮蔽度、海拔和跌水区5个关键环境因子。基于关键环境因子的实测值建立了栖息地适合度曲线，秦岭细鳞鲑分布的最适坡度范围为5%-10%，海拔分布范围为1500-2000 m，粗糙度范围0.3-0.4；跌水区密度范围12-18个/100 m，遮蔽度在0.5以上。

HABITAT ENVIRONMENTAL CHARACTERISTICS OF BRACHYMYSTAX LENOKTSINLINGENSIS

To evaluate the habitat preference of Brachymystax lenok tsinlingensis, fishes were caught for the habitat analysis from 25 sampling sites of Longxian and Qinzhou National Nature Reserve in June 2013. In total, 130 individua-ls were captured in 25 sites with the average density (0.10±0.07) ind./m. There was significant difference in the den-sity between two reserves. The fish density was positively correlated with slope, number of fall/pool, elevation, rough-ness, coverage, zoobenthos biomass, and velocity and it negatively associated with the river width, depth and dissolved oxygen. Redundancy Analysis (RDA) indicated that five key environmental factors (slope, roughness, coverage, eleva-tion and number of fall/pool) influenced the distribution of Brachymystax lenok tsinlingensis. Habitat suitability curve was established based on the five measured factors, and the best ranges of them were 5%—10%slope, 1500—2000 m altitude, 0.3—0.4 roughness, 12—18/100 m fall/pool, and more than 0.5 coverage, respectively.