THE EFFECTS OF IMPERVIOUS SURFACE, GEOMMORPHOLOGY, AND STREAMBED SCOUR DEPTH ON ESSENTIAL BROOK TROUT HABITAT

Abstract

Results of this study determined whether percentage of impervious land cover and geomorphology within the upstream drainage area of designated field sites would be predictive of average scour depth and whether this scour depth would have the potential to affect essential brook trout habitat. Impervious land cover in the upstream drainage area of all field sites, reach-level geomorphological data, and scour measurements collected throughout the summer and fall semesters of 2015 and the spring semester of 2016 were analyzed to determine any predictive or correlative relationships between brook trout density and stream geomorphology. These data were compared to total and young of the year (YOY) brook trout density data obtained from the Maryland Department of Natural Resources (MD DNR) and Maryland Biological Stream Survey (MBSS).

A Pearson correlation matrix and simple linear regression were used to analyze data within this study. Analyses showed brook trout density to be positively correlated with stream gradient and negatively correlated to impervious land cover. Total and YOY brook trout were negatively correlated to percent impervious cover (p < 0.05). Only total brook trout was positively correlated to stream gradient (p < 0.05). This indicated brook trout density to be predicted by percentage of impervious land cover and stream gradient. Additionally, pebble count modes were significantly correlated to stream gradient (p = 0.01). Scour depth, width to depth ratio, pebble count, and upstream drainage area were not statistically correlated to brook trout density in this study.