Impact of Fish Farming in floating cages on zooplankton Community in Euphrates River, Iraq

Abstract

The Impact of floating cages Fish culture on zooplankton in Euphrates river of middle of Iraq was examined from cage and non-cage site at monthly intervals from January 2018 to December 2019. the physical and chemical properties of river water were measured including Water Temperature, Turbidity,Total Solid suspended ( TSS), pH, Electrical Conductivity(EC),Total Dissolved Solids(TDS),Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD5),phosphate (PO4) and Nitrate (NO3),The results indicated that: the, Turbidity,Total Solid suspended ( TSS), pH, Electrical Conductivity, Total Dissolved Solids(TDS), Biochemical Oxygen Demand (BOD5), (PO4) phosphate and (NO3) Nitrate values in cage site were significantly higher than non-cage site (p<0.05) This gives evidence of the effect of fish cages on this properties. In the current study about 48 Taxonomic units of zooplankton were identified, the rotifer was dominate group including 23 taxa to rotifera, 12 taxa belonging to cladocera and 13 taxa to copepod. The Zooplankton showed high density in river 9470 ind/m3 during April in non-cage site while lower1100 ind/m3 in December in cage site also the rotifer recorder density from (425 ind/m3 in cage site to 4925 ind/m3 non-cage site), cladocera density from225 ind/m3 in cage site to 1850 ind/m3 in non-cage site and copepod density from 450 ind/m3 in cage site to 2695 ind/m3 non-cage the high values were in spring and autumn while lowest values were recorded in summer and winter. The results of relative abundance index showed that the species rotifera: Keratella cochlearis,K.valga, Euchlanis delatata while the cladocera Alona rectangular, Bosmina longirostris, Chydorus sphaericus, Simocephalus vetulus and the copepods: nauplii were more abundant in the Euphrates river at cage site. The Shanon-Weiner index of total Zooplankton varied from 1.81 to 4.13 bit/ind while the Shanon index of Rotifer from 1.85 to 3.78 bit/Ind, Cladocera varied from 0.001 to 3.04 bit/Ind and Copeoda varied from 0.35 to 2.71 bit/Ind with greatest values were recorded at April and September in non-cage site while lower values at and June and November in cage site that give evident to effect of cage on zooplankton.