Excess nutrients and algae blooms: Revealing deterioration of lakes in south-central Chile
Productive activities and the increase in population around lakes in central and southern Chile without adequate sewerage have deteriorated water quality. A new DGA monitoring project raises the alarm about the imbalance in lakes and lagoons between the O’Higgins and Biobío regions.
Lagos with green water and concern among bathers has been the tone of every summer in recent years. These cases are part of a process that affects more and more bodies of water in the country: the eutrophication.
Now, a monitoring by the General Directorate of Water (DGA) revealed increasing eutrophication, especially in coastal lagoons from the regions of O’Higgins y Biobío In addition to Lake Budi in The Araucanía.
Eutrophication
The process, which has also affected lakes such as Villarrica or Vichuquén, is called eutrophication; a phenomenon that occurs when there is a Increased nutrients in the water, especially phosphorus and nitrogen, which exceed the ecosystem’s capacity to assimilate them.
Thus, plants, algae and others organisms grow out of control generating an imbalance in the water that has effects on the health of people and the ecosystem, such as the mass death of fish.
The cause of this process is the accumulation of human activities that occur in the basin. One of the factors that generates the most concern is the increasing urbanization from these places, without having adequate treatment systems sewage. The fish farming and the plantations forestry of exotic species in the basin also generate this fertilization of aquatic systems.
Affected lakes
The lakes with the worst trophic conditions were the Swan Lagoon in the region of O’Higginsand the Green and Lo Mendez lagoons in it Biobío. These ecosystems presented hypereutrophy, that is to say a high content of nutrients in their waters. Similar situations were identified in the Round Lagoon in Biobío and in the Budi’s lake in Araucania.
The presence of was also monitored. cyanobacteria; microalgae blooms that are produced by the excess of nutrients and can eliminate the oxygen present in the water, unbalancing the ecosystem. A high presence of cyanobacteria was found in the Great Lagoon of San Pedro de La Paz in Biobío, and in the Budi Lake.
Los lakes monitored between La Araucanía and Los Lagosas they experienced lower temperatures, they showed a better trophic state. It should be noted that this monitoring focused on lakes about which there is little information. Other lakes such as Villarrica or Llanquihue, which are monitored in other areas, have presented algae blooms and eutrophication problems in recent years.
The monitoring was carried out by a team from the University of Concepción, with the DGA as the client.
Photo: DGA.
