Stream Algal Communities under potential climate change flow regimes


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.

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