Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, Chile
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...
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Sociedad de Biología de Chile
2011
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oai:scielo:S0716-078X20110003000102011-12-26Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, ChileKARRASCH,BERNHARDWOELFL,STEFANURRUTIA,ROBERTOGONZÁLEZ,JENNYVALDOVINOS,CLAUDIOCID,HERNÁNPARRA,OSCAR bacterioplankton extracellular enzymes heterotrophic flagellates 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 flagellates were encountered. Weak trophic interrelations were derived from a high bacteria-to-heterotrophic flagellate 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 specific 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.info:eu-repo/semantics/openAccessSociedad de Biología de ChileRevista chilena de historia natural v.84 n.3 20112011-09-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2011000300010en10.4067/S0716-078X2011000300010 |
| institution |
Scielo Chile |
| collection |
Scielo Chile |
| language |
English |
| topic |
bacterioplankton extracellular enzymes heterotrophic flagellates N-limitation, phytoplankton |
| spellingShingle |
bacterioplankton extracellular enzymes heterotrophic flagellates N-limitation, phytoplankton KARRASCH,BERNHARD WOELFL,STEFAN URRUTIA,ROBERTO GONZÁLEZ,JENNY VALDOVINOS,CLAUDIO CID,HERNÁN PARRA,OSCAR Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, Chile |
| description |
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 flagellates were encountered. Weak trophic interrelations were derived from a high bacteria-to-heterotrophic flagellate 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 specific 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. |
| author |
KARRASCH,BERNHARD WOELFL,STEFAN URRUTIA,ROBERTO GONZÁLEZ,JENNY VALDOVINOS,CLAUDIO CID,HERNÁN PARRA,OSCAR |
| author_facet |
KARRASCH,BERNHARD WOELFL,STEFAN URRUTIA,ROBERTO GONZÁLEZ,JENNY VALDOVINOS,CLAUDIO CID,HERNÁN PARRA,OSCAR |
| author_sort |
KARRASCH,BERNHARD |
| title |
Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, Chile |
| title_short |
Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, Chile |
| title_full |
Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, Chile |
| title_fullStr |
Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, Chile |
| title_full_unstemmed |
Ecomicrobiology and microbial assimilative capacity of the oligotrophic Andean Lake Laja, Chile |
| title_sort |
ecomicrobiology and microbial assimilative capacity of the oligotrophic andean lake laja, chile |
| publisher |
Sociedad de Biología de Chile |
| publishDate |
2011 |
| url |
http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2011000300010 |
| work_keys_str_mv |
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