River size as a determinant of lotic ecosystem structure: The case for suspended algae.

Abstract

Rivers have long been considered physically driven ecosystems, and the physical environment varies between streams and large rivers. The objective of this thesis was to investigate the importance of river size for suspended algal development. In the first chapter, I examine the seasonal variability of discharge, water chemistry, and suspended algal abundance to evaluate the accepted (but rarely tested) assumption that streams are more temporally variable than large rivers. Temporal variance of discharge and water quality parameters was determined for 114 stations on 104 rivers in eastern United States with data measured between May to October of 1978 by the U.S. National Stream Water Quality Accounting Network (NASQAN). In the second chapter, I examine suspended algal communities in 46 rivers in Ontario and Quebec to determine the influence of river size and nutrient status on algal biomass and size structure. Chlorophyll a estimates of size structure were compared with greatest axial linear dimension estimates (GALD) determined by microscope enumeration of suspended algal samples collected in 31 Ontario and Quebec rivers. (Abstract shortened by UMI.)