Seasonal dynamics of winter‐spring algal blooms in the temporary wetlands of Andean Patagonia, Argentina

Abstract

Algal blooms have profound impacts on freshwater ecosystems worldwide. This study investigates the dynamics of algal blooms in temporary wetlands within protected areas of northwestern Argentinean Patagonia. We characterised the algal community and biomass (measured by chlorophyll-a) in two wet meadows (Pitranto and Poza), assessing key environmental variables throughout the algal bloom. The blooms persisted from winter to early spring in 2023. Algal community composition varied between wetlands: at Pitranto, five green filamentous species, whereas at Poza, the community was primarily composed of the cyanobacterium Aphanocapsa sp., with a smaller proportion of filamentous algae. Excessive algal proliferation resulted in dense mats that blanketed the wetlands, attaching to vegetation and shading the water column, which, in turn, trapped macroinvertebrates within the mats. Cold winter temperatures triggered algal growth, and as water temperatures increased in early spring, the algae began to senesce. Chlorophyll-a concentrations and nutrient levels were lower than in previous years, likely due to nutrient depletion following efficient algal uptake. Sediment disturbance, exacerbated by invasive wild boar activity, may have altered nutrient dynamics and influenced algal blooms within these wetlands.