LIMNOLOGICAL DESCRIPTION OF 4 TEMPORARY PONDS IN THE DONANA-NATIONAL-PARK (SW, SPAIN)

Temporary ponds of Donana are small, shallow water bodies with alkalin e waters rich in Na+. Periodic wet and dry seasons force their biota t o function within a wide range of physical and chemical conditions. Th e ponds are basically fed by ground water and by direct rainfall durin g rainy periods. Thus, they are largely influenced by water table fluc tuations and groundwater chemical composition. These ponds are also su bject to frequent allochthonous inputs of nutrients and organic matter from adjacent terrestrial ecosystems. Their dependence on groundwater feeding has recently led some ponds to an endangered situation.