Heavy metals in bones from Harbour Porpoises Phocoena phocoena from the Western Black Sea Coast

During the last few years, the Western Black Sea coast has documented increase in the number of stranded marine mammals, particularly the harbour porpoise (Phocoena phocoena). This species is a subject to threats such as exposure to contaminants, fishery by-catch and introduced new marine species. The aim of this study was to analyse spatial and age trends in bone metal concentration in harbour porpoises from the Western Black Sea Coast. Selected heavy metals (Cu, Pb, Zn, Cd and Ni) were measured in bones of 33 harbour porpoises stranded along the Bulgarian Black Sea Coast from 2017. Spatially, we found higher metal levels in the harbour porpoises stranded in the Northern region compared with those from Southern region. The effect of aging was evident only for Zn content – the levels were higher in juveniles than in adults. The obtained results suggested that heavy metal contamination represent an important threat encountered by harbour porpoises

Cetacean mortality along the Bulgarian Black Sea Coast during 2017

The present study provides information on the stranding of cetaceans along the Bulgarian Black Sea Coast during 2017. Observations were made trough covering transects along the Bulgarian Black Sea Coast. A total of 198 cetaceans of three species were found - Harbor Porpoise (Phocoena phocoena), Bottlenose Dolphin (Tursiops truncatus), and Common Dolphin (Delphinus delphis). The most numerous were the harbor porpoise - 48% followed by the bottlenose dolphin - 15% and common dolphin - 8%. The most significant number of strandings was observed during July and August (54% of all cases). Cetacean strandings events were relatively highly concentrated in the area of Shabla, Varna and Pomorie

Are we ready to track climate-driven shifts in marine species across international boundaries? - A global survey of scientific bottom trawl data

Marine biota are redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of data availability, and mismatch between data and real species distributions. To assess the extent of this challenge, we review the global status and accessibility of ongoing scientific bottom trawl surveys. In total, we gathered metadata for 283,925 samples from 95 surveys conducted regularly from 2001 to 2019. We identified that 59% of the metadata collected are not publicly available, highlighting that the availability of data is the most important challenge to assess species redistributions under global climate change. Given that the primary purpose of surveys is to provide independent data to inform stock assessment of commercially important populations, we further highlight that single surveys do not cover the full range of the main commercial demersal fish species. An average of 18 surveys is needed to cover at least 50% of species ranges, demonstrating the importance of combining multiple surveys to evaluate species range shifts. We assess the potential for combining surveys to track transboundary species redistributions and show that differences in sampling schemes and inconsistency in sampling can be overcome with spatio-temporal modeling to follow species density redistributions. In light of our global assessment, we establish a framework for improving the management and conservation of transboundary and migrating marine demersal species. We provide directions to improve data availability and encourage countries to share survey data, to assess species vulnerabilities, and to support management adaptation in a time of climate-driven ocean changes.En prensa6,86

Molecular taxonomy study of representatives of the genus Gobius inhabiting coastal waters of Black Sea region

According to their origin the Black Sea gobies can be divided to Ponto-Caspian relicts and Mediterranean immigrants. The increase of species diversity in the Black Sea is a consequence of Mediterranean immigrants. The present study investigated the variability in Cytochrome b sequences isolated from two former Mediterranean immigrant species: Gobius niger and Zosterisessor ophiocephalus. The annotated at NCBI Cyt b sequences of the species were also used to extend the reach of the study. The analyses demonstrated that Black Sea inhabited by four haplotypes of G. niger. Four other haplotypes were found in sequences of Mediterranean black gobies. In the Black Sea haplotype, 6 is predominant and 83.5% of all G. niger representatives belong to it. Three other haplotypes (H_1; H_7 and H_8) were found to form isolated populations. The Tajima D-test indicated that in the Black Sea G. niger in a stage of expansion and significant evolutionary pressure according to data from Maximum Composite Likelihood model of Tamura-Nei, which can explain the accumulation of mutation and appearance of new haplotypes. Unlike G. niger, Z. ophiocephalus populations are shrinking according to Tajima D-test and only one haplotype is still surviving in isolated locations in the Black Sea. These data are in agreement with previous reports of other authors which alarmed that the grass goby is a critically endangered species close to extinction