Abstract Mammalian humerus shape is strongly predicted by loading and other functional factors. This constraint is lifted for cetaceans and, therefore, it could reflect other, specific evolutionary trends. For testing this hypothesis, the three-dimensional shape of the humerus for 32 taxa of extinct and extant cetaceans was analyzed. The shape variance was aligned with the parallel progressive evolution of diverging baleen and toothed whales. It showed a gradual advance of aquatic locomotion, with the trends of humeral head twist, diaphysis shortening and straightening, and epiphyses enlargement. Meanwhile, the phylogenetic signal was also seen in the morphospace as developments in the size and position of the humeral head and greater tubercle and diaphysis proportions. Modularity and integration patterns consistently changed through deep time and were independent of allometry. Paleogene whales had the most modular humerus, while the humerus of baleen whales was the most integrated. Also, the evolution of Hox genes regulating the humerus shape corresponded to their anatomical transformations and showed relaxed selection in cetaceans. In overall, the observed pattern well illustrated a “fly in a tube model” and showed its importance as an environment of emerging evolutionary innovations.

To date, 59 species (61 including infraspecific taxa) of the heterotrophic genus Protoperidinium have been found in the Black Sea. With rare exceptions, the records of most species were not confirmed by either line drawings or microphotographs, and lacked indications of important diagnostic traits. To partially correct these deficiencies, we conducted morphological examinations of the dominant Protoperidinium species in the Black Sea. The study provides original descriptions, line drawings, and microphotographs of 22 species of Protoperidinium with their global distribution maps. Protoperidinium quadrioblongum is reported from the Black Sea for the first time.

The recent exploitation of marine species is relatively well documented and understood in terms of impacts on species abundance, distribution, and resource use. In contrast, ancient exploitation of marine mammals remains poorly documented; in part, because a detailed meta-analysis of their presence in the zooarchaeological record is lacking. This is true in the Black Sea, where cetaceans are reported in the zooarchaeological record but have not yet been studied comprehensively. Here, we synthesize all available published and unpublished zooarchaeological data from 27 sites around the Black Sea, dating from the Mesolithic and Neolithic periods (6500-6000 BCE) to the Medieval period (641–1475 CE), to document the extent and nature of the exploitation of the Black Sea cetacean species. The results suggest that cetacean exploitation was practised continuously in the Black Sea over a period of 8500 years from the Neolithic through to the Medieval period. This suggests a much longer history of marine mammal exploitation in the Black Sea than previously understood, pushing back the timeline of human impacts on the Black Sea marine fauna.

A new species of Dinoflagellata—Protoperidinium euxinum Krachmalny sp. nov. (Protoperidiniaceae, Peridiniales) was described from the plankton of Odessa Bay (Black Sea). The species is morphologically close to P. steinii, P. mediterraneum and P. joergensenii. It differs from the listed species in elongated pentagonal body shape, conical epitheca with straight or concave lateral sides, inverse trapeziform hypotheca, and asymmetrical, laterally compressed plate 2a. Dimensions: 73.3–99.0 µm in length and 38.8–51.6 µm in width. Pictures and photomicrographs of the novel species are presented, along with detailed description and discussion.

Incidental catch in fishing gear (often known as bycatch) is a major mortality factor for the Black Sea harbour porpoise (Phocoena phocoena relicta), an endemic subspecies listed as Endangered in the IUCN Red List. The primary gear, responsible for porpoise bycatch in the Black Sea are bottom gillnets and trammel nets targeting turbot (Scophthalmus spp.), the most valuable commercial fish species in the Black Sea. From 2019 to 2021, a study was conducted in Bulgaria, Romania, Türkiye and Ukraine, to estimate the bycatch level in light of new information on porpoise distribution and abundance obtained from aerial surveys (CeNoBS) undertaken in 2019 as part of ACCOBAMS Survey Initiative (ASI). Bycatch data were collected by independent observers onboard turbot fishing boats (Bulgaria and Romania), complemented by questionnaire surveys and examination of stranded carcasses (in all countries). Some 48 monitoring trips took place (63 hauls by 11 different vessels). Cetaceans were caught on just over half of the trips (55%): 182 harbour porpoises, 4 bottlenose dolphins and 3 common dolphins. The median number of porpoises bycaught per trip was 1 (maximum 41) and the number of porpoises per km of net varied between 0 and 3.66 (median 0.1). Bycatch rates showed seasonal variation with marked increase in summer, compared to spring. The total annual bycatch of harbour porpoises in the Black Sea was roughly estimated as between 11 826 and 16 200 individuals. These numbers were the product of median values for effort (days/trips and vessels) and bycatch rate. Given the new estimates of porpoise abundance based on the CeNoBS survey of 2019 and reconciling abundance and bycatch estimates, harbour porpoise bycatch in the Black Sea represents between 4.6% - 17.2% of the estimated total population, depending on assumptions used. Even the most conservative estimate is among the highest worldwide and far exceeds the probable sustainable levels of around 1.0-1.7%. This study confirms that bycatch poses the most serious threat to the Black Sea harbour porpoises and that all riparian countries engaged in turbot fisheries must implement urgent measures to reduce it immediately, if the population is to survive in the long-term.

The krill surplus hypothesis of unlimited prey resources available for Antarctic predators due to commercial whaling in the 20th century has remained largely untested since the 1970s. Rapid warming of the Western Antarctic Peninsula (WAP) over the past 50 years has resulted in decreased seasonal ice cover and a reduction of krill. The latter is being exacerbated by a commercial krill fishery in the region. Despite this, humpback whale populations have increased but may be at a threshold for growth based on these human-induced changes. Understanding how climate-mediated variation in prey availability influences humpback whale population dynamics is critical for focused management and conservation actions. Using an 8-year dataset (2013-2020), we show that inter-annual humpback whale pregnancy rates, as determined from skin-blubber biopsy samples (n= 616), are positively correlated with krill availability and fluctuations in ice cover in the previous year. Pregnancy rates showed significant inter-annual variability, between 29% and 86%. Our results indicate that krill availability is in fact limiting and affecting reproductive rates, in contrast to the krill surplus hypothesis. This suggests that this population of humpback whales may be at a threshold for population growth due to prey limitations. As a result, continued warming and increased fishing along the WAP, which continue to reduce krill stocks, will likely impact this humpback whale population and other krill predators in the region. Humpback whales are sentinel species of ecosystem health, and changes in pregnancy rates can provide quantifiable signals of the impact of environmental change at the population level. Our findings must be considered paramount in developing new and more restrictive conservation and management plans for the Antarctic marine ecosystem and minimizing the negative impacts of human activities in the region.

The Black Sea is a semi-enclosed basin subject to major anthropogenic pressures, including marine litter and plastic pollution. Due to numerous large rivers draining into the basin and a population settled along the coast, the region could accumulate significant amounts of floating litter over time. Until now, only limited field data were available, and litter quantities and distribution remained unknown. In this study, floating marine macro litter (FMML) was assessed at the regional Black Sea scale for the first time, showing relatively high litter densities across the basin that reached a weighted mean of 81.5 items/km2. Monitoring data revealed an accumulation of floating items offshore in the eastern part of the basin, resembling on a small scale a ‘garbage patch’, where litter items were trapped, showing elevated densities in comparison to their surrounding areas. Most of these items were made of plastic materials (ca. 96%) and included large numbers of plastic and polystyrene fragments of small size ranges (2.5–10 cm). Harmonised field data collection through consistent and regular monitoring programmes across the region is essential to establish baselines and thresholds for large scale assessment at international level.

The distribution of the black rat (Rattus rattus) has been heavily influenced by its association with humans. The dispersal history of this non-native commensal rodent across Europe, however, remains poorly understood, and different introductions may have occurred during the Roman and medieval periods. Here, in order to reconstruct the population history of European black rats, we first generate a de novo genome assembly of the black rat. We then sequence 67 ancient and three modern black rat mitogenomes, and 36 ancient and three modern nuclear genomes from archaeological sites spanning the 1st-17th centuries CE in Europe and North Africa. Analyses of our newly reported sequences, together with published mitochondrial DNA sequences, confirm that black rats were introduced into the Mediterranean and Europe from Southwest Asia. Genomic analyses of the ancient rats reveal a population turnover in temperate Europe between the 6th and 10th centuries CE, coincident with an archaeologically attested decline in the black rat population. The near disappearance and re-emergence of black rats in Europe may have been the result of the breakdown of the Roman Empire, the First Plague Pandemic, and/or post-Roman climatic cooling.

The ability of bacteria to degrade organic pollutants influences their fate in the environment, impact on the other biota and accumulation in the food web. The aim of this study was to evaluate abundance and expression activity of the catabolic genes targeting widespread pollutants, such as polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and hexachloro-cyclohexane (HCH) in the Black Sea water column and sediments. Concentrations of PAHs, PCBs and HCH were determined by gas chromatography (GC) coupled to mass spectrometry (MS) and electron capture (ECD) detectors. bphA1, PAH-RHDα, nahAc, linA and linB that encode biphenyl 2,3 dioxygenase, α-subunits of ring hydroxylating dioxygenases, naphthalene dioxygenase, dehydrochlorinase and halidohydrolase correspondently were quantified by quantitative PCR. More recalcitrant PAHs, PCBs and HCH tended to accumulate in the Black Sea environments. In water samples, 3- and 4-ringed PAHs outnumbered naphthalene, while PAHs with > 4 rings prevailed in the sediments. Congeners with 4–8 chlorines with ortho-position of the substituents were the most abundant among the PCBs. β-HCH was determined at highest concentration in water samples, and total amount of HCH exceeded its legacy Environmental Quality Standard value. bphA1, was the most numerous gene in water layers (105 copies/mL) and sediments (105 copies/mg), followed by linB and PAH-RHDα genes (103 copies/mL; 105 copies/mg). The least abundant genes were linA (103 copies/mL; 104 copies/mg) and nahAc (102 copies/mL; 104 copies/mg). The most widely distributed gene bphА1 was one of the least expressed (10−3-10−2 copies/mL; 10−1 copies/mg). The most actively expressed genes were linB (101-102 copies/mL; 103 copies/mg), PAH-RHDα (101 copies/mL; 102 copies/mg) and linA (10−1-100 copies/mL; 100 copies/mg). Interaction of bacteria with PAHs, PCBs and HCH is evidenced by high copy numbers of the catabolic genes that initiate their degradation. More persistent compounds, such as high-molecular weight PAHs or β-HCH are accumulating in the Black Sea water and sediments, albeit microbial activity is directed against them.