Abstract

The distribution of macrozoobenthic fauna and the physicochemical properties of surface water along the Karasu coastline of Sakarya province in the southwest of the Black Sea (Türkiye) were investigated. Sediment samples were collected from 15 stations between the mouths of Sakarya River and Küçükboğaz Stream using the Ekman grab method, and the diversity of benthic organisms was evaluated using Shannon-Weaver Diversity Index and Margalef’s Species Richness Index. Physicochemical properties of water such as pH, conductivity, salinity, temperature, dissolved oxygen and oxygen saturation were also measured. The effects of these parameters on the distribution of benthic species were examined, and eight different benthic species were identified. Donax sp. (19%) was found to be the most common species, while Rapana venosa (3%) was the rarest. Water quality parameters were evaluated considering the impact of the Sakarya River and the Küçükboğaz Stream on the region. It was observed that the distribution of benthic species was directly affected by breakwater and coastal erosion, which had a positive effect on the distribution of species such as Mytilus galloprovincialis and Donax sp. Although the Black Sea ecosystem is inefficient in terms of general species diversity, the region studied can be considered biologically productive. The study is also important because it provides horizontal observation of benthic organisms on the southwestern Black Sea coast and identifies risks of habitat loss along the coast.

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