Detection of Zooplankton Fauna in Downstream of Euphrates

Zooplankton samples were taken for determination of the zooplankton fauna of the lower Euphrates basin (between Birecik Dam Lake and Karkamış Dam Lake). In the study, 10 families from Rotifera, 6 families from Cladocera and 4 families from Copepoda, totally 20 family were found. A total of 41 zooplankton species were identified. From Rotifera, Lepadellidae was the most species rich family with 4 species, from Cladocera, Daphnidae was the most species rich family with 4 species and from Copepoda, Cyclopoidae was the most species rich family with 7 species.


Introduction
Wetlands that are regarded as natural resources of the world because of their biodiversity; are the most important ecosystems of the earth with their natural functions and economic values.They regulate the water regime of the region by feeding or discharging underground waters, storing flood waters, controlling floods, and preventing the entry of sea water on coasts.They have a positive effect on the local climatic factors, mainly rainfall and temperature, by raising the humidity in the region.
The primary function of freshwater zooplankton is an important component in aquatic ecosystems, which act as primary and secondary links in the food chain.Zooplankton community structure is affected by physical and chemical environment.These communities are also affected by biological interactions, predation and their competition for food resources (Neves et al. 2003).Most groups of zooplankton have been used as a bioindicator for monitoring aquatic ecosystems and the integrity of water.Zooplankton community may be considered as a bioindicators of eutrophication, because they are coupled to environmental conditions, responding more rapidly to changes than do fishes, and are easier to identify than phytoplankton.Therefore, they are potential value as water quality indicators (Sládecek 1983;Murugan et al. 1998).
This study was carried out to determine the zooplankton fauna of the lower Euphrates basin, where no studies have been conducted on zooplankton until now.

Results
In the study a total of 41 species were found, including 19, 12 and 10 taxa belonging to Rotifera, Cladocera and Copepoda, respectively.Six families were detected from Cladocera, Daphnidae was the most species rich family with 4 species followed by Chydoridae with 3 species.Porcellionidae, Bosminidae and Sididae had the least species followed by Eurycercidae with 2 species.In the Copepoda with four families, Cyclopoidae had 7 species and others, Diaptomidae, Ameiridae and Canthocamptidae had 1 species each one.It was determined that some species with wide spread from Rotifera, Cephalodella gibba (Ehrenberg, 1838), Keratella cochlearis (Gosse, 1851), K. tropica (Apstein, 1907)

Discussion
No studies have been found on zooplankton in the Downstream of Euphrates.But some zooplankton studies found belong to the upper parts of the Euphrates River.These studies; Saler et al. (2015) reported that they found 32 species from Rotifera, 5 species from Cladocera and 2 species from Copepoda.Rabee (2010) reported that 32 taxa belonged to Rotifera, 12 to the Cladocera and 7 to the Copepoda in Euphrates River in the North part of Iraq.Saler et al. (2014) declared that they found 15 species from Rotifera, 6 species from Cladocera and 2 species from Copepoda were identified in Uzunçayır Dam Lake in the North part of the Euphrates River.Bulut and Saler (2014) declared that they found in 25 species from Rotifera, 6 species from Cladocera and 2 species from Copepoda in Murat River (between Elazığ and Palu).It is seen that there are significant differences in species diversity between our study and other studies.The reason of this, Euphrates system is a very large river system.In order to it passes through two geographical regions, it is under the influence of different climate zone.Thus its zooplankton content varies considerably in terms of quality and quantity.
Rotifera is the dominant group among all zooplankton groups qualitatively and quantitatively in freshwater ecosystem (Saksena 1987).The result obtained in the study was accordance with results of Saksena (1987).
It was reported that almost all species found in the study wide spread, common, cosmopolitan (Eldredge and Evenhuis 2003;Hutchinson 1967;Ruttner-Kolisko 1974;Braioni and Gelmini 1983;Ramdani et al. 2001) and they were reported from lots of study inland waters of Turkey (Ustaoğlu et al. 2004).
The presence of identified species in the study seems to be compatible with their ecological characters.