5 research outputs found
Seasonal ecosystem variability in remote mountain lakes: implications for detecting climatic signals in sediment records.
22 páginas, 12 figuras, 20 tablas.Weather variation and climate fluctuations are the main sources of ecosystem variability in remote mountain lakes.
Here we describe the main patterns of seasonal variability in the ecosystems of nine lakes in Europe, and discuss
the implications for recording climatic features in their sediments. Despite the diversity in latitude and size, the
lakes showed a number of common features. They were ice-covered between 5–9 months, and all but one were
dimictic. This particular lake was long and shallow, and wind action episodically mixed the water column throughout
the ice-free period. All lakes showed characteristic oxygen depletion during the ice-covered-period, which was
greater in the most productive lakes. Two types of lakes were distinguished according to the number of production
peaks during the ice-free season. Lakes with longer summer stratification tended to have two productive periods: one at the onset of stratification, and the other during the autumn overturn. Lakes with shorter stratification had a
single peak during the ice-free period. All lakes presented deep chlorophyll maxima during summer stratification,
and subsurface chlorophyll maxima beneath the ice. Phosphorus limitation was common to all lakes, since nitrogen
compounds were significantly more abundant than the requirements for the primary production observed. The
major chemical components present in the lakes showed a short but extreme dilution during thawing. Certain lake
features may favour the recording of particular climatic fluctuations, for instance: lakes with two distinct productive
periods, climatic fluctuations in spring or autumn (e.g., through chrysophycean cysts); lakes with higher oxygen
consumption, climatic factors affecting the duration of the ice-cover (e.g., through low-oxygen tolerant
chironomids); lakes with higher water retention time; changes in atmospheric deposition (e.g., through carbon or
pigment burial); lakes with longer stratification, air temperature changes during summer and autumn (e.g., through
all epilimnetic species).This study was supported by the European Commission,
Environment and Climate Programme, contract ENV4
CT95 0007 (MOLAR) and by the Swiss Federal Office
of Education and Science (grant no. 95.0518-1).Peer reviewe
Seasonal ecosystem variability in remote mountain lakes. Implications for detecting climatic signals in sediment records.
22 páginas, 12 figuras, 20 tablas.Weather variation and climate fluctuations are the main sources of ecosystem variability in remote mountain lakes.
Here we describe the main patterns of seasonal variability in the ecosystems of nine lakes in Europe, and discuss
the implications for recording climatic features in their sediments. Despite the diversity in latitude and size, the
lakes showed a number of common features. They were ice-covered between 5–9 months, and all but one were
dimictic. This particular lake was long and shallow, and wind action episodically mixed the water column throughout
the ice-free period. All lakes showed characteristic oxygen depletion during the ice-covered-period, which was
greater in the most productive lakes. Two types of lakes were distinguished according to the number of production
peaks during the ice-free season. Lakes with longer summer stratification tended to have two productive periods: one at the onset of stratification, and the other during the autumn overturn. Lakes with shorter stratification had a
single peak during the ice-free period. All lakes presented deep chlorophyll maxima during summer stratification,
and subsurface chlorophyll maxima beneath the ice. Phosphorus limitation was common to all lakes, since nitrogen
compounds were significantly more abundant than the requirements for the primary production observed. The
major chemical components present in the lakes showed a short but extreme dilution during thawing. Certain lake
features may favour the recording of particular climatic fluctuations, for instance: lakes with two distinct productive
periods, climatic fluctuations in spring or autumn (e.g., through chrysophycean cysts); lakes with higher oxygen
consumption, climatic factors affecting the duration of the ice-cover (e.g., through low-oxygen tolerant
chironomids); lakes with higher water retention time; changes in atmospheric deposition (e.g., through carbon or
pigment burial); lakes with longer stratification, air temperature changes during summer and autumn (e.g., through
all epilimnetic species).This study was supported by the European Commission,
Environment and Climate Programme, contract ENV4
CT95 0007 (MOLAR) and by the Swiss Federal Office
of Education and Science (grant no. 95.0518-1).Peer reviewe