The effect of salinity and other environmental parameters on the diatom community and ecological status of the Karstic Azmak streams flowing into the Gökova Bay (Türkiye)
摘要
The Azmak streams (Kadın, Akçapınar, and Çamlı) are a unique system fed by underground springs of karstic origin and then flowing into the Gökova Bay, with salinity (SAL) values varying even from upstream to downstream. A total of seven stations were selected and seasonal sampling was carried out between October 2022 and August 2023 to determine the spatial and temporal differences of SAL and other environmental parameters on the ecological status and diatom community dynamics [species richness, Shannon diversity index, percentage (%) of habitat status of the identified taxa to the total number of species in each site, and species composition] in these streams. SAL was the most effective parameter affecting the habitat preferences of the species (fresh, brackish, etc.), the distribution of dominant species, and species composition among the sites. The spatial differences in water temperature (T), sulfate (SO4), nitrite-nitrogen (NO2-N), and soluble silica (Si), and the temporal differences in total phosphorus (TP) and orthophosphate (PO4-P) also affected the dominant species. TP, NO2-N, and SO4 were the main parameters affecting the spatial and temporal variation of the Shannon diversity index and species richness, while the variation in SAL had no effect. Among the 15 different diatom indices used, the ROTTs was the most consistent index in determining the ecological status of the sites together with effective stressors (TP, SAL, SO4, NO2-N, Si) and indicator species.