Distribution of non-marine ostracods in the streams of the Ceyhan River Basin (Turkey) and assessment of their indicator properties for water quality

The potential of ostracod species as indicators of water quality and the influence of key ecological parameters on their distribution were evaluated by collecting samples from 39 streams during the spring, summer, and autumn seasons. Thirty-seven ostracod taxa (23 living, 14 subfossil) were identified, with Hemicypris anomala (Klie, 1938) being newly reported for Turkey. The summer season exhibited the highest diversity, indicated by the highest Shannon index value of 2.119, while the spring season showed the lowest diversity with a Shannon index value of 1.673. The variability in species composition was greater in the autumn than in other seasons. Among the nine factors affecting species distribution, the first three were found to be total nitrogen, magnesium, and elevation. Ilyocypris decipiens Masi, 1905 and Stenocypris intermedia Klie, 1932 indicated medium water quality in relation to the electrical conductivity, dissolved oxygen, total nitrogen and phosphorus. Stenocypris intermedia depicted waters of medium quality for biological oxygen demand and poor quality for nitrate. Ilyocypris monstrifica fi ca (Norman, 1862) signaled waters of good quality for total nitrogen and medium quality for dissolved oxygen. Potamocypris fallax Fox, 1967 and Potamocypris similis G.W. M & uuml;ller, 1912 characterized good and medium water quality regarding dissolved oxygen and total phosphorus, respectively. Cypridopsis vidua (O.F. M & uuml;ller, 1776) was identified fi ed as a positive-pollution indicator related to ammonium. The results suggest that ostracods have great potential as indicators of water quality, but more detailed studies on water quality parameters and ostracods are needed.