Extreme freshwater ecosystems in Patagonia: The Copahue-Agrio system

TEMPORETTI PEDRO; BAFFICO GUSTAVO; DIAZ MÓNICA; BEAMUD GUADALUPE; NICHELA DANIELA; CABRERA JUAN ; PEDROZO FERNANDO

FRESHWATERS AND WETLANDS OF PATAGONIA. ECOSYSTEMS AND SOCIOECOLOGICAL ASPECTS

Springer Nature Switzerland AG

Año: 2022;

Thechapter compiles 20 years of research work carried out in the River Agrio-Lake Caviahuesystem by the Water Quality and Aquatic Resources Research Group. This systemis characterized by its natural gradient of acidity, as well as concentrationand transport of nutrients and metals, which is expressed in low diversity ofspecies, both in lake plankton and river epilithic communities. The replacementof algal species (seasonal succession) does not occur in the lake under low pHconditions (Avg. 2.5). The low pH allows most of the elements present to remainin solution, conditioning environments with a high content of metals andphosphorus in the Upper River Agrio section and Lake Caviahue. In recent years,the lake has experienced a significant increase of at least one pH unit, (asituation that is controlled by magmatic activity), causing changes in chemicalcomposition. If the increase continues, it is expected to affect the epilithicand phytoplanktonic compositions. This fact is unprecedented for aquatic environmentsin Argentina. The chapter covers a) basic aspects such as water chemistry,nutrient loadings, trophic status, algal communities (phytoplankton andepilithic algae), the geochemistry of sediments and their role in metal andnutrient dynamics, and b) applied aspects such as the use of acidophilic algaeas indicators of remediation processes of soils contaminated by hydrocarbons,the behaviour of a naturally acidic lake as a Fenton reactor, and the use of suchenvironments as a potential sentinel for nutrient deposition in Patagonia.