A Foundational Study of the Dehram River’s Aquatic Ecosystem: Bridging Fresh and Brackish Water

In this study, we explore Dehram river system, focusing on its biological characteristics, in a hot arid region. This is a freshwater stream flowing over salt formations. We examined various ecological aspects of the river, including its benthic macroinvertebrates, zooplankton, fishes, as well as some physical and chemical factors in three selected stations. The river showed variations in physical and chemical properties, with salinity and conductivity levels being the most significant. Salinity, total dissolved solids, calcium ion concentration, and nitrate levels increased downstream in the study area. Our findings revealed 13 macroinvertebrate orders present in the river, including a new record for Fars Province - the hydrobiid gastropod Ecrobia grimmi. The discovery of the four fish species in the river marked a new addition to their known geographical distribution. Certain invertebrate families were unique to station 1 and/or 2, while families Dyticidae and Simuliidae were exclusive to station 3. Other families were found in all three stations. Fish groups in the river included four identified cyprinid species, revealing new distribution ranges for them. Capoeta barroisi, known for tolerating specific environmental conditions, was found to adapt to the higher temperature, EC, and pH ranges in the river, setting new ecological records. The river exhibited unique ecological conditions such as high temperature and  extranormal conductivity levels, which may have led to specific adaptations in its biota. We recommend further detailed investigations to determine whether these are new species or highly adapted populations isolated geographically and physiologically.