Decade of microplastic alteration in the southeastern black sea: An example of seahorse gastrointestinal tracts.

Unconscious and excessive use of plastic supports the diversity and abundance of microplastics (MPs) in marine environments. As a result of MP exposure, organisms in the marine environment are faced with adverse scenarios up to death. In this study, ten-year MP composition was investigated in gastrointestinal tracts (GITs) of low-mobility seahorses (90 individuals per period) from the Southeastern Black Sea. Seahorse GITs sampled during both 2012 and 2022 contain 102 and 135 MP items, respectively. The number of MPs per unit individual seahorse and unit seahorse weight was higher in the 2022 period. On the other hands, no significant differences were observed between the MP lengths of both periods. The majority of MPs in both sample periods were materials shorter than 1000 µm. Of the eight found synthetic polymers, five belonged to the 2012 period, while seven were observed during the 2022 period. Additionally, the most abundant synthetic polymer for both periods is polyvinyl stearate (PVS). As a result, 43% of the total plastic material belonged to the 2012 period, while 57% was observed in the 2022 period. Considering both the diversity of polymers and the abundance of plastics, the region was adversely affected by plastic materials in the 2022 period.

Population genetic structure of the short-beaked common dolphin from the Black Sea and the Turkish Straits System.

Our study aims to assess the population connectivity, evolutionary history, and conservation status of the short-beaked common dolphin in the Black Sea and Turkish Straits System (TSS). We also include DNA sequences from the Atlantic Ocean and the Mediterranean Sea to provide a regional perspective to our localized study. Analysis of 366 base pairs of mitochondrial DNA D-loop fragments from 37 samples collected from short-beaked common dolphins in the Black Sea, TSS, and Aegean Sea revealed 13 haplotypes, eight of which have not been previously reported. While analysis of samples archived on GenBank revealed 89 different haplotypes across the region. The haplotype network contains two main peripheral groups that include individuals from all locations. Haplotypes from the Atlantic Ocean are scattered across the network and no obvious population separation was detected. Some shared haplotypes potentially indicate multi-directional colonization events of the Mediterranean Sea from the eastern Atlantic Ocean. Moreover, some less widely distributed haplotypes suggest some level of more recent genetic connectivity through the Strait of Gibraltar and the TSS and point out the importance of these straits in the dispersal of short-beaked common dolphins. The haplotype and nucleotide diversity values were lower in the Black Sea, TSS, and western Mediterranean Sea when compared to the Atlantic Ocean, supporting the expansion of Atlantic populations into the Mediterranean and the Black Seas. Differentiation was observed between the Atlantic Ocean, and the Mediterranean Sea, TSS and the Black Sea based on Фst but not between Mediterranean and the Black Seas. For common dolphins, which have high dispersal potential, the protection of open seas and narrow seaways to enhance connectivity may be crucial.

Is there a distinct harbor porpoise subpopulation in the Marmara Sea?

Genetic population structure of geographically isolated endangered Black Sea harbor porpoise (Phocoena phocoena relicta) is little known in Turkish waters, especially in the Turkish Straits System (TSS- Marmara Sea, Bosphorus and Dardanelles), which connects the Black Sea and the Aegean Sea. Mitochondrial DNA sequences of 70 new individuals sampled in the Turkish Black Sea, TSS and Aegean Sea, revealed five new haplotypes from the Black Sea. The findings support the idea that harbor porpoises from the Black Sea dispersed into the Aegean through the TSS. Considering signatures of population expansion, all subpopulations showed a signature of population expansion. The network data and the Фst calculations indicated that the Marmara Sea subpopulation was significantly differentiated from all of the other subpopulations, and supports the notion of its isolated. The finding of a potential management unit (MU) within an already heavily impacted subpopulation as a whole suggests that the individuals of P. p. relicta inhabiting the Marmara Sea require a very rigorous conservation strategy to ensure the survival of this subpopulation, represented by its unique haplotype.