The freshwaters and wetlands of Patagonia: Ecosystems and socioecological aspects

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

Extreme freshwater ecosystems in Patagonia: The Copahue-Agrio system

Springer

Lugar: Cham; Año: 2022; p. 1 - 540

The chapter compiles 20 years of research work carried out in the River Agrio-Lake Caviahue system by the Water Quality and Aquatic Resources Research Group. This system is characterized by its natural gradient of acidity, and concentration and transport of nutrients and metals, which is expressed in a low diversity of species in both lake plankton and river epilithic community. The replacement of algal species (seasonal succession) does not occur in the lake under low pH (Avg. 2.5) conditions. The low pH allows most of the elements present to remain in solution, conditioning environments with a high content of metals and phosphorus 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, a situation that is controlled by magmatic activity, causing changes in chemical composition. If the increase continues, it is expected to affect the epilithic and phytoplanktonic compositions. This fact is unprecedented for aquatic environments in Argentina. The chapter will cover a) basic aspects such as water chemistry, nutrient loading, trophic status, algal communities (phytoplankton and epilithic algae), sediment geochemistry and their role in metal and nutrient dynamics, and b) applied aspects such as the use of acidophilic algae as indicators of remediation processes of soils contaminated by hydrocarbons, the behaviour of a naturally acidic lake as a Fenton reactor, and the use of such environments as a potential sentinel for nutrient deposition in Patagonia.