Chapter 3.1 - Water Physicochemistry in Intermittent Rivers and Ephemeral Streams

Abstract

In this chapter, we explore how the dynamics of key physicochemical parameters (temperature, light, salinity, pH, dissolved oxygen, and turbidity) differ in intermittent rivers and ephemeral streams (IRES) compared to their perennial counterparts. Disruption of longitudinal, lateral, and vertical hydrological connectivity through intermittence explains many of the differences in the physicochemistry between IRES and perennial systems. Physicochemical conditions affect the structure and functioning of all aquatic ecosystems; however, because of the greater variability (e.g., substantial daily, seasonal, and supraseasonal variation in parameters like dissolved oxygen, temperature, and pH) in IRES compared to perennial systems, changes in the physicochemistry are particularly important in defining the ecological conditions of IRES. IRES are especially vulnerable to anthropogenic inputs because their low water volume during flow cessation limits their dilution capacity. Understanding the processes responsible for the natural temporal and spatial variability in the physicochemistry in IRES informs the design and implementation of effective conservation and management plans in IRES.