Phoxinus abanticus, a new species from the Lake Abant drainage in Türkiye (Teleostei: Leuciscidae).

Phoxinus abanticus, a new species, is described from the Lake Abant basin. It is distinguished from Phoxinus species in Türkiye and adjacent waters by the presence of fewer lateral line scales (60-69, vs. 75-91 in Phoxinus colchicus, 75-90 in Phoxinus strandjae); a deeper caudal peduncle (caudal peduncle depth: 1.8-2.3 times in length, vs. 2.4-2.9 in P. colchicus; 2.5-3.2 in P. strandjae); the absence of scales in the breast of males (vs. present); and ventral body reddish in nuptial colouration pattern for male (vs. brackish). The new species, P. abanticus, is also distinguished from its closest relative, P. strandjae, by a minimum of 3.40% genetic distance in the mtDNA cytochrome b (cyt b) gene.

Heavy Metal Concentrations in Trachurus Mediterraneus and Merlangius Merlangus Captured from Marmara Sea, Turkey and Associated Health Risks.

Rapid industrialization and excessive human population growth may cause deterioration in marine water quality and biodiversity. Heavy metals are one of the most common pollutants in the seas and marine organisms, including demersal and pelagic fish, can accumulate them from the environment. Assessment of the ecological risk of heavy metals from fish has an important role in public health. In this study, some heavy metal (Pb, Cd, As, Cr, Hg, Cu, Zn, and Fe) concentrations were determined in the muscle tissues of two commonly consumed fish species, Trachurus mediterraneus (Mediterranean horse mackerel) and Merlangius merlangus (Whiting), which are the fifth (14,222 tons/year) and sixth (6814 tons/year) highest commercial catches of marine fish species in Turkey, respectively. Heavy metal concentrations of samples collected from four sites (Adalar, Izmit Bay, Yalova, and Tekirdag) in the Marmara Sea were determined using ICP-MS. Fish samples caught at Yalova station were found to have the highest heavy metal concentrations. According to the World Health Organization (WHO), in terms of the mean values, only As, and Cr were higher than permissible limits in T. mediterraneus, while Pb, Cd, As, and Cr were higher in M. merlangus. Arsenic concentrations were higher than maximum limits in both T. mediterraneus and M. merlangus. The estimated weekly intake (EWI) was calculated to assess the potential health impact. The EWI for arsenic, cadmium, lead, and mercury for some sites was above the provisional tolerable weekly intake.

The bitterling-mussel coevolutionary relationship in areas of recent and ancient sympatry.

Host-parasite relationships are often characterized by the rapid evolution of parasite adaptations to exploit their host, and counteradaptations in the host to avoid the costs imposed by parasitism. Hence, the current coevolutionary state between a parasite and its hosts is predicted to vary according to the history of sympatry and local abundance of interacting species. We compared a unique reciprocal coevolutionary relationship of a fish, the European bitterling (Rhodeus amarus) and freshwater mussels (Unionidae) between areas of recent (Central Europe) and ancient (Turkey) sympatry. Bitterling parasitize freshwater mussels by laying their eggs in the gills of mussel and, in turn, mussel larvae (glochidia) parasitize the fish. We found that all bitterling from both regions avoided one mussel species. Preferences among other mussel species tended to be related to local mussel abundance rather than duration of sympatry. Individual fish were not consistent in their oviposition choices, precluding the evolution of host-specific lineages. Mussels were demonstrated to have evolved strong defenses to bitterling parasitism in the area of ancient sympatry, but have no such defenses in the large areas of Europe where bitterling are currently invasive. Bitterling avoided glochidia infection irrespective of the duration of sympatry.