Ecological study of two gastropods species Melanoides turbuculata and Melanopsis preaemorsa from Euphrates river - Basrah, Iraq

Biological and taxonomic studies of snails in the waters of Iraq's desert have been enhanced through seasonal recording of them, and it is one of the means to follow their distribution and determine the density. Aiming to determine occurrence and density of two snails Melanoides tuberculata and  Melanopsi preaemorsa, in two stations at the Euphrates river-Basrah, Governorate, in Al-Madina and Al-Qurna. Three replicates within each station were chosen for sample collection of these two species using the quadrate (25 × 25) cm. Many environmental factors including temperature, salinity, pH, dissolved oxygen (DO), and organic material in sediment were measured, 5,330 samples were obtained from the stations. The highest annual density was recorded by snail M. turbuculata with 2,745 and 1,072 ind/m² in two stations respectively, while M. preaemorsa with 912 and 601 ind/m² in (St.1 and 2), respectively. The densities of snail M. turbuculata from 480 ind./m2, June 2019 at (St. 1) to 57 ind./m2 in December 2019. And in (St. 2) from 256 ind./m2 in May 2019 to 0 ind./m2 in August - December 2019. While snail species M. preaemorsa (Linnaeus, 1758) in (St. 1) from 128 ind./m2 in June and July to 0 ind./m2 in January-February, November-December 2019 and in (St. 2) from 144 ind./m2 in April to 0 ind./m2 in August-December 2019. The statistical analysis found significant differences in DO, temperatures, and snail density in two stations. This is the first study in the region on these two species in particular, and their abundance.