Organic and Inorganic Carbon Drives Zooplankton Composition in Tigris River Within Baghdad

Increasing availability of organic and inorganic carbon in aquatic ecosystems became a common phenomenon that was influenced by manmade activities and ongoing climate change, which could influence zooplankton communities. Zooplankton composition in Tigris River under the effects of dissolved organic and inorganic carbon inputs (DOC and CO2) has not been studied yet. Hence, we studied those impacts by taking three locations that were distributed in Tigris River within Baghdad City. Eighty-four taxa of zooplankton have been recognized during the study. These taxa were divided into three main groups that are: Rotifera forms 69.04% and Cladocera forms 16.66%, while Copepoda forms 14.28% of the total taxa number of zooplankton. Constancy index and relative abundance showed that there are some zooplankton taxa that were persistent and added species in the Tigris River, and these taxa are either dominant, abundant, less abundant or rare zooplankton species. Zooplankton community composition and abundance were negatively controlled by DOC and CO2 availability, with the well-known influences of other environmental variables [e.g., water temperature (WT), pH and DO]. The negative relationship between zooplankton abundance and carbon availabilities implies that climate-change and increased carbon inputs could change the food web structure of freshwater rivers.