Environmental factors controlling the development of microbial mats in inland saline lakes; the granulometric composition of the sediment

Abstract

The presence of inland saline and alkaline lakes is one of the most original limnological features of the Iberian Peninsula. These waterbodies are associated with endorheic phenomena that occur in arid and semi-arid climates. On a global basis, inland saline lakes are common (Williams 1986), but in Western Europe, these lakes are confined to the Iberian Peninsula. The Spanish continental salt and soda lakes lakes occur in groups known as endorheic centers (see Fig. 1). These lakes encompass a broad variety of different physico-chemical conditions, seasonal fluctuations and sediment features. Lake Chiprana (Aragon) is the only deep permanent hypersaline lake in Spain (Guerrero et al. 1991). In contrast, all other inland saline and alkaline lakes in Spain are temporal water basins which contain water during 3 to 10 months of the year. During the inundation periods, the water level and concomitantly the salinity is subjected to extreme temporal fluctuations. The ionic composition of these lakes has been studied previously (Montes and Martino 1987; Comin and Alonso 1988). In summary, the Spanish inland lakes encompass a wide spectrum of ionic types: in the Andalusian lakes, sodium predominates with either chloride or sulphate as the dominant anion; the lakes in La Mancha mainly contain magnesium sulphate; and the lakes in Aragon encompass a whole range from sodium chloride to magnesium sulphate.