Molecular and biological studies of nonindigenous and extremely rare fish species from the western Baltic reported from the Pomeranian Bay (southwest Baltic Proper)

Abstract

W ięcaszek B., P anicz R., E ljasik P., Tański A., B ushra A. 2023. Molecular and biological studies of nonindigenous and extremely rare fish species from the western Baltic reported from the Pomeranian Bay (southwest Baltic Proper). Folia Biologica (Kraków) 71: 181-194. Water inflows from the North Sea to the Baltic Sea are recognized as a significant factor influencing the diversity of fish species in the region. In this report, we present findings on three newly discovered fish species (Solea solea, Merluccius merluccius, and Limanda limanda) and the presence of species that were previously seldom observed in the Pomeranian Bay and the associated oligohaline waters of Szczecin Lagoon. These fishes were incidentally captured during monitoring surveys of commercially important fish species. Species identification relied on partial sequences of cytochrome c oxidase subunit I (COI), cytochrome b (cytb), and rhodopsin (rho) genes, as well as morphometric diagnostic characteristics. Upon comparing the obtained sequences with GenBank records, it was revealed that the sequences for Merluccius merluccius (rho, GenBank acc. no. OM737733) and Chelidonichthys lucerna (cytb, GenBank acc. no. OM737734) constitute new DNA barcodes. The majority of sequences obtained in our study matched those available in GenBank for fishes inhabiting the North Sea, suggesting spatial and temporal linkages between the two seas. The remaining sequences exhibited similarity to data from the Cantabrian Sea, the coasts of France, and the Norwegian Sea. The study results, in conjunction with information on the inflows of saline waters and data from previous studies on reported fish occurrences, indicate that the bycatch species could serve as potential bioindicators of environmental changes in the study area.