Resumen de Aspectos generales de la limnología invernal de dos lagos pirenaicos morfológicamente muy distintos (Estany Redó y Estany Baciver)

Enric Ballesteros Sagarra, Jordi Catalan, Lluís Camarero Galindo, E. Garcia

• español

  El estudio del periodo invemal en dos lagos pirenaicos de caractensticas tróficas y de mineralizaci6n similares, pero morfológicamente muy distintos, ha permitido comparar la influencia de la profundidad y la tasa de renovación del agua sobre algunos aspectos caracteristicos de este periodo: el decrecimiento de la biomasa fitoplanctónica, el consumo de oxigeno, la supervivencia de macrófitos, etc. Las distintas fases de la dinámica de la cubierta (formación del hielo, acumulación y metamorfismo de la nieve, los procesos de inundación y hundimiento, el deshielo) afectaron de distinta manera los procesos bajo el hielo en los dos lagos.

• English

  Most lakes in the Pyrenees have an ice cover about half of the year. The information about this period is scarce. Comparing the winter period of two lakes of similar trophic and chemical features but quite different morphology, we studied the influence of depth and spring flushing in several processes: phytoplankton decay, macrophyte winter survival, water chemistry and oxygen consumption. In the dynamics of the winter cover severa1 processes can be distinguished: ice formation, snow accukulation and metamorphism, flooding processes, and thawing. These processes had different influences in the water mass below ice depending on the lake morphology. In the shallowest lake, Isoetes growing at little depth\ere squashed by the subsidence of the cover owing to the flooding processes and hydrostatic arrangement. Phytoplankton decayed very slowly in the deepest lake, because of depth and the absence of wash-out. On the other hand, in the shallowest lake, phytoplankton growth was more important during the regressive periods of the cover that allowed light penetration, probably because of a shorter nutrient recycling length. Oxygen saturation decreased more in the lake with higher ratio between sediment surface and volume, in spite of its location in a valley that maintained the stream flow during all the winter. In this lake, changes in the chemistry of the input water affected the entire water mass during thaw, drastic changes succeeded in a short time. In contrast, the deepest lake maintained a near-surface water flow during most of the thaw because lake cover melted slower than the watershed snowpack, only at the end of the period was there a renewal of water at most of the depths.

• català

  L'estudi del període hivernal en dos llacs pirenaics de característiques tròfiques i de mineralizació semblants, però morfològicament molt diferents, ha permes comparar la influència de la profunditat i la taxa de renovació de l'aigua sobre alguns aspectes característics d'aquest període: el decrexeiment de la biomasa fitoplanctònica, el consum d'oxigen, la supervivència de macròfits, etc. Les diferents fases de la dinhica de la cuberta (formació del gel, accumulació i metamorfisme de la neu, els processos d'inundació i enfonsament, el desgel) afectaren de diferent manera els processos sota el gel en els dos llacs