Freshwater Gastropoda in Diyala River: A Study on Diversity, Distribution, and Environmental Variation

Abstract

This field study investigated the diversity, spatiotemporal distribution, and environmental relations of freshwater gastropods in the Diyala River (Iraq). Monthly surveys were conducted from September 2024 to March 2025 at three stream sites (Mahroot, Al-Saria, Rose), recording gastropod densities and water quality variables (temperature, pH, dissolved oxygen, and electrical conductivity). Six gastropod species were identified: Physa acuta, Melanopsis costata, Theodoxus jordani, Melanoides tuberculata, Bellamya bengalensis, and Lymnaea sp., with species richness varying from 4 to 6 across sites. The most abundant taxa were Melanoides tuberculata and Bellamya bengalensis. In contrast, Melanopsis costata and Theodoxus jordani were exclusive to Al-Saria in late winter. Community structure changed seasonally, with Melanoides tuberculata peaking in autumn and Bellamya bengalensis, Lymnaea sp., and Physa acuta increasing in winter. Temperature ranged from ~29°C to ~9°C, with slight changes in pH (7.2–8.8), dissolved oxygen (6.3–8.8 mg/L), and conductivity (520–680 μS/cm). Results highlight the value of combining seasonal biological surveys with physico-chemical monitoring for biodiversity conservation and biomonitoring.