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

An extensive survey was undertaken of 117 (mostly helocrene-type) springs o n the eastern Iberian Peninsula to generate an ostracod database of use for palaeoecological studies. For this purpose, the main physico-chemical para meters of the habitat, including water chemistry, temperature, pH and oxyge n content, were recorded. Twenty-eight species, with an average of two spec ies 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 ran acid little-known speci es is validated. Autoecological traits, deduced by means of Canonical Corre spondence Analysis (CCA), have allowed the main habitat factors affecting t he distribution of non-marine ostracods in this area to be determined. Acco rding to this analysis, four groups of springs, each one characterised by p rincipal and secondary species, are distinguished: (1) Bicarbonate-rich spr ings with relatively low water temperature, low mineralisation and wet clim ate are characterised by Potamocypris zschokkei, Herpetocypris intermedia, and secondary species Ilyocypris bradyi, Ilyocypris inermis, Potamocypris v illosa and Cyclocypris ovum. (2) Bicarbonate-rich springs with warm and oxy genated waters are characterised by Herpetocypris brevicaudata, S. lanzarot ensis and Cypridopsis vidua as main species, and Notodromas persica, P. vil losa and Cyclocypris ovum as secondary species. These latter two species ar e related to wetter climates and higher altitudes. (3) Bicarbonate-rich wat ers enriched with sulphate and/or chloride, also with warm water and often with high mineral content. Characteristic species are Paralimnocythere mess anai, Ilyocypris gibba and Pseudocandona pratensis and secondary species He terocypris incongruens, Heterocypris salina, Darwinula stevensoni, C. vidua , and Herpetocypris helenae (4) The last group is defined by brackish sulph ate-rich and chlorinated waters with high temperature, and it is mainly com posed 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 combinatio n of biogeographical factors (i.e. latitude) and the relatively constant co nditions of the springs (i.e. constant temperature) may explain the common occurrence of species which had previously been reported only in distant ar eas. S. lanzarotensis and P. messanai are examples of such species, their d istributions were thought to be confined to the Canary Islands and the Ital ian Peninsula, respectively. Distinctive morphological carapace traits are provided for most species to facilitate the use of these ostracod species i n the interpretation of past environments from sedimentary deposits. (C) 19 99 Elsevier Science B.V. All rights reserved.