Publication Details

Category Text Publication
Reference Category Journals
DOI 10.4067/S0716-078X2011000300010
Title (Primary) Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, Chile
Author Karrasch, B.; Woelfl, S.; Urrutia, R.; González, J.; Valdovinos, C.; Cid, H.; Parra, O.
Journal Revista Chilena de Historia Natural
Year 2011
Department FLOEK
Volume 84
Issue 3
Page From 433
Page To 450
Language englisch
Keywords bacterioplankton; extracellular enzymes; heterotrophic fl agellates; N-limitation; phytoplankton

A strong socio-economic development pressure in South Chile will more and more cause an impact to the present lakes and rivers. Nevertheless, our knowledge concerning the ecological structure and the microbial self-purification capabilities of these lacustrine water bodies is scant but essential for a future sustainable development of land and water use. We studied Lake Laja, a lake already heavily impacted by water diversions for hydropower generation and irrigation. Typical for the Andean region Lake Laja is an oligotrophic water body, limited by nitrogen nutrients. Only very low chlorophyll a and particulate organic carbon (POC) concentrations and a small abundance and biomass of bacteria (mainly ultramicrobacteria) and heterotrophic fl agellates were encountered. Weak trophic interrelations were derived from a high bacteria-to-heterotrophic fl agellate ratio. For the ten investigated extracellular enzymes (alkaline phosphatase, leucine-, arginine-, glycine- and tyrosine-aminopeptidase, α-, β-D-glucosidase, α-, β-D-galactosidase, N-acetyl-β-D-glucosaminidase), with the exception of α-D-glucosidase, a broad range of organic matter degradation activities was proven. Probably, due to the N-limitation, organic nitrogen hydrolysing extracellular enzymes reached activities on average of 45 % compared to other studies in oligotrophic waters. The possible effect of N-limitation on extracellular enzyme activities was more pronounced by cell specifi c extracellular enzymatic activity rates, which exceeded those of other oligotrophic water bodies on average by factor 2. The overall activities of all microbial extracellular enzymes studied proved to be dominated by the dissolved free external enzymes (up to 98 %) over the ectoenzymes which are associated with particulate organic matter (bacterial cell walls, particles, and aggregates). It is concluded that future socio-economic changes, dealing with watershed human intervention (accelerating inorganic and organic loads) as well as global change (temperature and precipitation changes) could lead to significant changes in the ecology of Lake Laja.
Persistent UFZ Identifier
Karrasch, B., Woelfl, S., Urrutia, R., González, J., Valdovinos, C., Cid, H., Parra, O. (2011):
Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, Chile
Rev. Chil. Hist. Nat. 84 (3), 433 - 450