DISTRIBUTION PATTERNS OF OSTRACODS IN IBERIAN SALINE LAKES - INFLUENCE OF ECOLOGICAL FACTORS

A limnological survey of the Iberian mesosaline and hypersaline lakes allowed study of biogeographical and ecological aspects of their ostracod populations. Eucypris aragonica Brehm & Margalef; Eucypris mareotica (Fischer) and Heterocypris barbara inermis (Gauthier) are the only species found in waters with salinities between 10 and 100‰. Each species tends to be restricted to one of the three large Iberian Tertiary depressions: E. aragonica in the Ebro River basin; E. mareotica in the Guadalquivir River basin (South Spain) and H. barbara inermis in the tableland of La Mancha (Central Spain). Both E. mareotica and H. barbara inermis are distributed in inland waters of regions around the Mediterranean Sea, while E. aragonica is only known from Spain. Historical factors have been traditionally used to account for the distribution of several crustacean species and recent faunas have been seen as the remnat of those inhabiting Tertiary Depressions around ancient Mediterranean Sea. Ecological factors, mainly ion composition, account for their observed distribution pattern in Spanish lakes. E. mareotica typically inhabits high chloride waters while H. barbara inermis 'prefers' lakes with high sulphate. E. aragonica seems to be restricted to chloride waters with a high sulphate content and very irregular (or aperiodic) hydrological regimes. Presence of parthenogenetic populations and waterfowl exchange between different saline-lake areas in the Iberian Peninsula facilitate ostracod dispersion. © 1990 Kluwer Academic Publishers.