The study was conducted in Karasu Stream (Sinop Province, Black Sea Region of Turkey). The purpose of this study is, to determine the benthic macroinvertebrate composition of the stream, together with some of its environmental characteristics (water temperature, pH and dissolved oxygen) to evaluate the trophic level of the stream. Samplings of benthic macroinvertebrates and environmental variables were performed monthly at ten stations between February 2013 and January 2014. As a result, 18260 specimens were investigated and 175 taxa were determined. Chironomidae and Oligochaeta were the higher groups in terms of species richness with 48 and 38 taxa, respectively. The BMWP and ASPT indices indicate that all the stations belong to “slightly polluted (Class II)” or “unpolluted (Class I)” water quality levels.

The Konya Closed Basin (KCB) in Türkiye plays a key role in agricultural production and freshwater supply. However, the basin is impacted by humanly derived nitrogenous compounds and toxic metals. Keeping the water quality at a potable level in the basin is compulsory. This study was part of a project yielding monitoring of water quality in KCB in accordance with the Water Framework Directive (2000/60/EC). Eleven stations, except Beyşehir Lake and Mamasın Dam, were sampled for the first time for freshwater molluscs. Community structure indexes and multivariate statistical analyses were applied to determine the microhabitats of gastropods and their responses to environmental changes. The structure and distribution of gastropod assemblages differed depending on total phosphate, total nitrogen, dissolved oxygen, and pH. This study revealed that most of the gastropods in KCB are relatively tolerant to biodegradable pollution. However, there is a strong observed decline in population size requiring intensive future monitoring; measures have to be taken to preserve the remaining populations. Two endemic species need an urgent action plan to protect their habitats: Theodoxus anatolicus of Çeltik Canal and Bithynia pseudemmericia of Beyşehir Lake; a re-assessment of their extinction risk according to the IUCN rules is needed (2022). The results of this study will be useful for comparison with future studies to document potential improvements or continued ecological regression in the quality of aquatic ecosystems in the watershed.

In this study, Çubuk 2, Kesikköprü and Asartepe Dam Lake, were investigated. A total of 60 sediment samples were collected and the concentrations of 10 elements (Cu, Pb, Zn, Ni, Mn, Fe, Co, Cr, Al, As) were determined. The obtained findings were compared to the limit values for the sediment quality guidelines (SQGs) and were investigated using sediment assessment methods. The results indicate that the values for SQGs revealed that the concentrations of Ni and As should be emphasised. Toxic unit (TU) values showed that As and Ni together constitute 69.95–80.09% of the total toxic effect alone for all lakes. In addition, the Contamination factor (Cf) and Enrichment factor (EF) detected the concentration of As for Kesikköprü Dam Lake as being at a medium and higher accumulation levels, although the Geoaccumulation index (Igeo) detected that As leads to contamination below the medium level. When the total element accumulation was evaluated, no risk was detected for the lakes. Cluster analysis (CA) revealed quite different elemental profiles for 3 lakes. The strongest correlation between the elements was observed for Cu-Ni (r = 0.942) in Çubuk 2, whereas Çubuk 2 was the lake with the highest seasonal elemental variation among the lakes investigated.

In this study, which carried out on Sarıncof Lake on 13 July 2021, 27 species from Rotifera, 6 from Cladocera, and 3 from Copepoda, belonging to zooplankton groups were identified in a total of 36 species. Among the identified species, Rotifers were the dominant group with a rate of 51 %. This was followed by Copepoda 28.3 % and Cladocera 20.7 %, respectively. The identified species are the first record for Sarıncof Lake, which is the subject of the study.