Physical properties of the environment relevant to the pelagic ecosystem of a deep high-mountain lake (Estany Redó, Central Pyrenees)

Resum

From an ecological approach the physical environment of lakes can be summarized by four components: temperature, light, turbulence and Lhe morphology of the basin and its watershed. The variabWity Lhrough an annual cycle of Lhese components of Lhe physical environment of the Estany Redó is described in the paper and their implicattions for Lhe dynamics of its biota are examined. The ratio between catchment area size (155 hm2 ) and lake volumen (7.75 hm3 ) is extremally small.The value of relaLive depth is extraordinarilly high (1 3 %). Both aspects contribute to the oligotrophy of Lhe lake. Because of the hypsographic configuration of the lake Redó there is a sediment focusing above 40 m and between 15 and 25 m. Production peak s should be linked to the interaction of the mixing layer with these sediment-rich bottoms. Other implications of the temperature, the light and the mixing time scales in the lake biological dynamics are also examined.