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Abstract. Ostracods are common lacustrine calcitic microfossils. Their faunal assemblage and morphological characteristics are important ecological proxies, and their valves are archives of geochemical information related to palaeoclimatic and palaeohydrological changes. In an attempt to assess ostracod ecology (taxonomic diversity and valve morphology) combined with valve geochemistry (δ18O and δ13C) as palaeosalinity indicators, we analysed sedimentary material from the International Continental Scientific Drilling Program (ICDP) Ahlat Ridge site from a terminal and alkaline lake, Lake Van (Turkey), covering the last 150 kyr. Despite a low species diversity, the ostracod faunal assemblage reacted sensitively to changes in the concentration of total dissolved salts in their aquatic environment. Limnocythere inopinata is present throughout the studied interval, while Limnocythere sp. A is restricted to the Last Glacial period and related to increased lake water salinity and alkalinity. The presence of species belonging to the genus Candona is limited to periods of lower salinity. Valves of Limnocytherinae species (incl. L. inopinata) display nodes (hollow protrusions) during intervals of increased salinity. Both the number of noded valves and the number of nodes per valve appear to increase with rising salinity, suggesting that node formation is related to hydrological changes (salinity and/or alkalinity). In contrast to Lake Van's bulk δ18O record, the δ18O values of ostracod valves do record relative changes of the lake volume, with lower values during high lake level periods. The δ13C values of different species reflect ostracod habitat preferences (i.e. infaunal vs. epifaunal) but are less sensitive to hydrological changes. However, combined with other proxies, decreasing Holocene δ13C values may indicate a freshening of the lake water compared to the low lake level during the Last Glacial period. The Lake Van example underscores the significance and value of coupling ostracod ecology and valve geochemistry in palaeoenvironmental studies of endorheic lake basins.

-To understand ostracod distribution and ecology at high altitudes (1659-2889 m a.s.l.), 78 different aquatic sites located in the city of Van were sampled during summer of 2009. A total of 29 ostracod species were recorded in 57 sites. Among the species, Trajancypris laevis (G.W. Mu¨ller 1900), is a new report for the Turkish ostracod fauna. First axis of Canonical Correspondence Analysis (CCA) explained about 68% of the relationships between the 13 most abundant species and environmental variables. Four variables (redox potential, habitat type, pH and electrical conductivity) had the greatest effect on species composition (P < 0.01). Twenty-six species encountered from 38 stations were restricted between 1659 and 1750 m a.s.l. Above 1750 m a.s.l., the numbers of species were not significantly affected by altitude (P > 0.05). Three species (Heterocypris incongruens (Ramdohr, 1808), Ilyocypris bradyi Sars, 1890 and Potamocypris villosa (Jurine, 1820)) occurred extensively from 1650 to 2350 m a.s.l. Spearman rank correlation revealed a negative relationship between Limnocythere inopinata (Baird, 1843) and altitude (r = x 0.894, P = 0.05), while two species (I. bradyi and Prionocypris zenkeri (Chyzer and Toth, 1858)) had a positive correlation to dissolved oxygen (P = 0.05). There was a significantly negative relationship between Ilyocypris inermis Kaufmann, 1900 and electrical conductivity, and H. incongruens showed a significant correlation to station type. Five groups of species were determined by UPGMA analysis. Species in each cluster were grouped according to ecological conditions suitable for them. Results revealed that species ecological tolerances and optimum levels can be species-specific but species with cosmopolitan distributions tend to have high tolerance ranges to different variables, including altitudinal changes.

To understand the relationship between local (alpha) diversity of ostracods and their distribution, 95 different locations were randomly sampled from southern Kahramanmaraş (Turkey) between 7 June and 31 July, 2010. Total of 46 ostracods were encountered from 68 sites. Four alpha diversity indices (Shannon‐Wiener, Menhinick, Brillouin, Margalef) individually quantified higher species diversity and evenness for three types of habitats (limnocrene springs, ponds, stream). Diversity partitioning analyses revealed a significant and substantial beta‐diversity among the sites. First axis of CCA exhibited about 71% of the correlations between species and environmental variables. Water temperature, having either a negative or positive correlation with individual species, was the most influential factor affecting diversity. Altitude did not significantly affect the numbers of species identified from the elevation ranges of 400–600 m and 800–1000 m. At least nine cosmopolitan species from 56 sites had an important contribution to local diversity. Hence, suitability of aquatic (ecological) conditions and habitat types provide better explanations for ostracod diversity than do other abiotic factors such as altitude, pH and salinity. The results may support the Habitat Diversity Hypothesis but the study needs to be expanded to different regions and cannot be generalized at the moment. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We investigated how the richness and ecological characteristics of non-marine ostracod species varied across nine 100-m elevation bands (from 549 to 1457 m) in theÇankırı region. We collected a total of 37 taxa (25 living and 12 sub-recent) from 114 of 130 aquatic sites sampled during September of 2011; 34 of the taxa were new records for the region. Eight widely distributed 'cosmopolitan' species (Candona neglecta, Cypridopsis vidua, Heterocypris incongruens, Ilyocypris bradyi, Limnocythere inopinata, Potamocypris villosa, Prionocypris zenkeri, and Psychrodromus olivaceus) were found more frequently than other species. The first two axes of canonical correspondence analyses (CCA) explained 73.2% of the correlation between 11 species and 5 environmental variables. Of which, electrical conductivity (F D 3.99, p D 0.028) and altitude (F D 2.69, p D 0.004) were the most explanatory (p < 0.05) variables for species. Optimum altitude and water temperature values of the cosmopolitan species were relatively higher than the other species. Significant regression models (p < 0.01, r 2 D 0.81) indicate that the frequency of occurrence was affected by changes in numbers of samplings sites from 549 to 1457 m. When highest numbers of species (15 spp.) were found at the range of 1231À1332 m, numbers of asexual species (10 spp.) were twice of the sexual species (5 spp.) with no statistical difference between numbers of swimming (7 spp.) and non-swimming (8 spp.) species. Results were discussed based on the ecological conditions that individual species prefer.