Abstract
The Llanquihue lake is included in the called Araucanian or Nord Patagonian lakes located between 38-41° S. These lakes are characterized by their oligo-mesotrophic status due to human intervention which takes to the increase in nutrients inputs from industries and towns. Effects on zooplankton assemblages are observed with marked increase of daphnids abundance. The aim of the present study is to analyze the trophic status and zooplankton relative abundance in different bays of Llanquihue lake. It was found direct associations between chlorophyll a with daphnids percentage, total dissolved nitrogen with reactive soluble phosphorus nitrogen/phosphorus molar radio with cyclopoids percentage, and an inverse relation between daphnids and calanoids percentages. The occurrence of three kinds of microcrustacean assemblages and environmental conditions was evidenced: the first one with high calanoids percentage, low species number and low chlorophyll and nutrients concentration, a second with moderate chlorophyll and nutrients concentration and moderate daphnids percentage; high species number and a third site with high chlorophyll and nutrients concentration, high daphnids percentage and high species number. Daphnids increase under mesotrophic status, agree with similar results observed for southern Argentinean and New Zealand lakes.
Highlights
The called Araucanian or Nord Patagonian lakes are located in Argentina and Chile between 38-41° S, these lakes are characterized by their oligo or oligomesotrophic status, and glacial origin (Thomasson, 1963)
These lakes have low zooplankton species number with marked higher calanoid abundance compared to daphnids in oligotrophic status which can observed under oligomesotrophic status (Modenutti et al, 1998; De los Ríos-Escalante, 2010)
The Pearson index correlation matrix generated by principal component analysis (PCA) shows direct significant correlations between dissolved inorganic nitrogen and reactive soluble phosphorus, daphnids percentage with chlorophyll “a” concentration”, daphnids percentage with cyclopoids percentage and nitrogen/phosphorus molar ratio with cyclopoids abundance, species number with N/P ratio, and daphnids with cyclopoids percentages
Summary
The called Araucanian or Nord Patagonian lakes are located in Argentina and Chile between 38-41° S, these lakes are characterized by their oligo or oligomesotrophic status, and glacial origin (Thomasson, 1963) These lakes have low zooplankton species number with marked higher calanoid abundance compared to daphnids in oligotrophic status which can observed under oligomesotrophic status (Modenutti et al, 1998; De los Ríos-Escalante, 2010). These lakes located in Chile has marked human intervention due to changes in their surrounding basins, because the original native forest was replaced by towns, agricultural, and industrial activities, with consequent nutrient inputs (Soto, 2002). The aim of the present study is to analyze the zooplankton assemblages in different bays of Llanquihue lake in order to determine the potential role of nutrient and chlorophyll concentration on distinct zooplankton groups abundance
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