Effects of climate-related changes in flow on stream algal communities.

Abstract

Climate change predictions show increases in droughts and extreme precipitation events in the future. These types of events disturb aquatic stream ecosystems, and with increased droughts brings greater chances of stagnant pool forming out of drying streams. To further understand the consequences of increased stagnant pool formation and disturbance on stream algal communities, this experiment tested how stream algae responded to stagnant conditions and stagnant conditions with periods of high flow, mimicking extreme precipitation events. Chlorophyll amounts were used to estimate total amount of algae, and random field identification was used to check community composition. Both treatments were shown to decrease overall biomass of algae, regardless of stagnation duration. Both treatments also showed loses in Fragilaria algae, and streams experiencing the drought only treatment gained larger populations of loosely attached Mougeotia and Merismopedia. The overall changes in community suggest that highly-attached species of algae suffer in stagnant conditions.