RELATING FLUVIAL GEOMORPHOLOGY TO MACROINVERTEBRATE DISTRIBUTION

Modern rivers undergo constant stress from disturbances such as bank stabilization, channelization, dams, and water expenditures. As these anthropogenic activities persist, efficient methods of characterizing rivers remain essential. Macroinvertebrates are an important feature in evaluating fluvial health, because they are often the first to react to contaminants. These toxins can be transferred through macroinvertebrates to other trophic levels. The purpose of this research was to use a geospatial model to differentiate instream macroinvertebrate habitats, and determine if the model is a viable method for stream evaluation. Through the use of ArcGIS and digital elevation models, the geomorphology of the Qu’Appelle River, Saskatchewan was assessed. Four geomorphological characteristics of the river were isolated (sinuosity, slope, fractal dimension, stream width) and clustered through a Principle Component Analysis, yielding sets of river reaches with similar geomorphological characteristics, called typologies. These typologies were mapped to form a geospatial model of the river, and grouped into geomorphological response units (GRUs). Macroinvertebrate data were aligned to the model, revealing relationships between macroinvertebrate taxa and fluvial geomorphology. A Kruskal-Wallis analysis and post hoc pairwise multiple comparisons pinpointed significant relationships between several genera and typologies. Furthermore, certain GRUs contained more sensitive macroinvertebrate families and healthier levels of diversity than other GRUs. Typologies were better suited to relate geomorphology to macroinvertebrate taxa, because they represented a more direct relationship to localised geomorphological characteristics than GRUs