Ostracoda from springs on the eastern Iberian Peninsula: ecology, biogeography and palaeolimnological implications

Abstract

An extensive survey was undertaken of 117 (mostly helocrene-type) springs on the eastern Iberian Peninsula to generate an ostracod database of use for palaeoecological studies. For this purpose, the main physico-chemical parameters of the habitat, including water chemistry, temperature, pH and oxygen content, were recorded. Twenty-eight species, with an average of two species per site, were recorded. Some of these are new records for the Iberian Peninsula ( Sarscypridopsis lanzarotensis and Paralimnocythere messanai). In addition, the presence in this area of several rare and little-known species is validated. Autoecological traits, deduced by means of Canonical Correspondence Analysis (CCA), have allowed the main habitat factors affecting the distribution of non-marine ostracods in this area to be determined. According to this analysis, four groups of springs, each one characterised by principal and secondary species, are distinguished: (1) Bicarbonate-rich springs with relatively low water temperature, low mineralisation and wet climate are characterised by Potamocypris zschokkei, Herpetocypris intermedia, and secondary species Ilyocypris bradyi, Ilyocypris inermis, Potamocypris villosa and Cyclocypris ovum. (2) Bicarbonate-rich springs with warm and oxygenated waters are characterised by Herpetocypris brevicaudata, S. lanzarotensis and Cypridopsis vidua as main species, and Notodromas persica, P. villosa and Cyclocypris ovum as secondary species. These latter two species are related to wetter climates and higher altitudes. (3) Bicarbonate-rich waters enriched with sulphate and/or chloride, also with warm water and often with high mineral content. Characteristic species are Paralimnocythere messanai, Ilyocypris gibba and Pseudocandona pratensis and secondary species Heterocypris incongruens, Heterocypris salina, Darwinula stevensoni, C. vidua, and Herpetocypris helenae (4) The last group is defined by brackish sulphate-rich and chlorinated waters with high temperature, and it is mainly composed of typical brackish species as Cyprideis torosa, Xestoleberis nitida or Loxoconcha elliptica. Secondary species are Sarscypridopsis cf. aculeata, Paralimnocythere psammophila, D. stevensoni and H. salina. The combination of biogeographical factors (i.e. latitude) and the relatively constant conditions of the springs (i.e. constant temperature) may explain the common occurrence of species which had previously been reported only in distant areas. S. lanzarotensis and P. messanai are examples of such species, their distributions were thought to be confined to the Canary Islands and the Italian Peninsula, respectively. Distinctive morphological carapace traits are provided for most species to facilitate the use of these ostracod species in the interpretation of past environments from sedimentary deposits.