Robbins Jeff, Pyron Mark
Department of Biology Ball State University Muncie IN USA.
Ecol Evol. 2021 Mar 18;11(9):4542-4549. doi: 10.1002/ece3.7349. eCollection 2021 May.
River hydrogeomorphology is a potential predictor of ecosystem and assemblage variation. We tested for fish assemblage variation as a function of hydrogeomorphology in a Midwestern US large river, the Wabash River. Fish data were classified by taxonomy and traits and we tested if assemblages varied with river hydrogeomorphology or river distance, defined into 10-km distinct reaches. Three unique geomorphological units, Functional Process Zones (FPZ), were identified using an ArcGIS hydrogeomorphic model, based primarily on channel width, floodplain width, and down valley slope. Five locations were identified as FPZ A with narrow stream channel, high down valley slope, and an expansive floodplain. Ten locations were identified as FPZ B with a wide river channel and wide floodplain. Thirty-five locations were identified as FPZ C with wide river channel and a constrained floodplain. The sites were categorized into three stream orders: 5, 6, and 7. We found hydrogeomorphology classified by unique FPZs or by river distance influenced taxonomic and functional fish assemblages for the Wabash River. There was high overlap among fish occurrences among FPZs, but nine species resulted as significant indicators of specific FPZs. Five traits were significant indicators of FPZs: an intermediate Swim Factor score, medium tolerance to silt, small-large stream size preference, and two Shape Factor categories. Our conclusions are that fish assemblages respond strongly to local geomorphology and river distance, fitting the riverine ecosystem synthesis and the river continuum concept.
河流地貌学是生态系统和生物群落变化的一个潜在预测指标。我们在美国中西部的一条大河——沃巴什河中，测试了鱼类群落变化与河流地貌学之间的关系。鱼类数据按分类学和特征进行了分类，我们检验了生物群落是否随河流地貌学或河流距离而变化，河流距离被划分为10公里的不同河段。使用ArcGIS水文地貌模型确定了三个独特的地貌单元，即功能过程区（FPZ），主要依据河道宽度、洪泛平原宽度和河谷下游坡度。五个地点被确定为FPZ A，其溪流河道狭窄，河谷下游坡度大，洪泛平原广阔。十个地点被确定为FPZ B，其河道宽阔，洪泛平原广阔。三十五个地点被确定为FPZ C，其河道宽阔，洪泛平原受限。这些地点被分为三个河流等级：5级、6级和7级。我们发现，按独特的功能过程区或河流距离分类的水文地貌学影响了沃巴什河的鱼类分类学和功能群落。功能过程区之间的鱼类出现情况有很高的重叠，但有9种鱼类成为特定功能过程区的显著指示物种。有五个特征是功能过程区的显著指示特征：中等游泳因子得分、对淤泥的中等耐受性、中小河流大小偏好以及两种形状因子类别。我们的结论是，鱼类群落对当地地貌和河流距离反应强烈，符合河流生态系统综合理论和河流连续体概念。
