Marine Biological Journal

Distribution of polychaetes of the family Spionidae (Annelida) on the shelf of the northwestern part of the Black Sea

2023-09-05T07:58:21+00:00

The northwestern part of the Black Sea (NWBS) is a vast shallow water area, biocenoses of which are an important component of the Black Sea ecosystem. Since the benthos of this region has not been studied in recent decades, data on its current state are relevant. A significant contribution to the taxonomic composition of macrozoobenthos is made by polychaetes of the family Spionidae, which are represented by a large number of species and are characterized by high abundance rates. The aim of the research is to study the species composition, distribution, and quantitative development of polychaetes of the family Spionidae in the NWBS at depths of more than 10–15 m. The material used was macrozoobenthos sampled from 160 stations (230 samples) during research cruises of the RV “Maria S. Merian” and the RV “Professor Vodyanitsky” in 2010–2017 at depths from 10 to 137 m. Bottom sediments were sampled with an Ocean-25 bottom grab (capture area of 0.25 m²) and a box corer (S = 0.1 m²). Bottom sediments were washed through sieves with the smallest mesh diameter of 1 mm. On the surveyed shelf area of the NWBS, 83 Polychaeta species were found, including 12 Spionidae species. Polychaetes were recorded at all the stations performed, while spionids were noted at 66% of their total number. At single stations, up to 6 Spionidae species were registered, but more often, there were 2–3 species. In total, 11 species were identified: Aonides paucibranchiata Southern, 1914, Dipolydora quadrilobata (Jacobi, 1883), Microspio mecznikowiana (Claparède, 1869), Prionospio cf. cirrifera Wirén, 1883, Polydora cornuta Bosc, 1802, Pygospio elegans Claparède, 1863, Scolelepis tridentata (Southern, 1914), Scolelepis (Scolelepis) cantabra (Rioja, 1918), Spio decorata Bobretzky, 1871, Laonice cf. cirrata (M. Sars, 1851), and Marenzelleria neglecta Sikorski & Bick, 2004. Non-identified specimens of the genus Prionospio were registered as well. Spionidae distribution in the water area of the NWBS is uneven, which is due to the response of certain species to various environmental factors. The maximum density of spionids was 2,984 ind.·m⁻², and the average density was (477 ± 126) ind.·m⁻². The highest density of Spionidae was observed in the depth range of 20–40 m. In terms of density, P. cf. cirrifera, A. paucibranchiata, and D. quadrilobata predominated. Out of identified species, three (M. neglecta, P. cornuta, and D. quadrilobata) are non-native for the Black Sea. In the taxonomic composition of Polychaeta of the NWBS, Spionidae accounted for 14%, while in the quantitative representation, their contribution reached 42% of the total density of polychaetes. This indicates a significant role of this family in the functioning of the benthic ecosystem of the NWBS.

Functional morphology and morphological variability of the operculum of Rapana venosa (Gastropoda, Muricidae)

2023-09-05T08:02:20+00:00

The gastropod Rapana venosa has spread from the Western Pacific to the Black Sea, Mediterranean Sea, and coastal areas on both sides of the Atlantic Ocean largely due to its ecological and morphological plasticity. Numerous works have been devoted to the study of the variability of the rapa whelk shell. The functional morphology and morphological variability of the R. venosa operculum have been insufficiently studied, and the description of this exosomatic organ is given only schematically. Based on the analysis of 190 R. venosa specimens sampled in two areas of the Black Sea, detailed description is given, and trends in the morphological variability of the operculum are shown depending on the specimen age and size. The characteristics determining the normal and aberrant development of the operculum are evaluated. It is shown for the first time that R. venosa has regenerative capabilities, up to the restoration of the lost operculum, and morphogenetic adaptive potential. A manifestation of this potential is the formation of a hypertrophied large operculum, with the shape that is not characteristic of any other Muricidae species and gastropods in general. Apparently, the abnormal size and shape of the operculum are a defensive response to pressure from predators, especially crabs. The previously unknown ability to regenerate the operculum broadens the understanding of the physiological capabilities of the rapa whelk. The phenomenon of operculum formation with a unique shape for gastropods is another manifestation of morphological plasticity, which made R. venosa one of the most successful invasive species in the modern marine environment.

Marine mammals of the Kola Bay, Barents Sea

2023-09-05T07:26:43+00:00

Despite the fact that publications focused on marine mammals of the Barents Sea are quite numerous, relevant data on their habitat in the Kola Bay area are scarce. The latest work detailing this aspect dates back to 1997. At the same time, protected species of marine mammals (listed in the Red Data Book of the Russian Federation) occur in the bay waters. With the progressive implementation of the Integrated Development of the Murmansk Transport Hub project, the anthropogenic load on the Kola Bay water area may increase multifold. Therefore, research on marine mammals occurring in its waters becomes more and more relevant. This paper provides an updated list of marine mammals registered in the Kola Bay, which is compiled on the basis of published data and observations of the authors.

Spatial and temporal dynamics of the phytoplankton biomass in the surface layer of the Black Sea

2023-09-05T08:08:29+00:00

The spatial and temporal variability of phytoplankton biomass in the surface layer of the Black Sea during an 18-year period is analyzed, and the effect of the main currents in the sea on the spatial and temporal dynamics of phototrophic phytoplankton biomass is assessed. Regular long-term chlorophyll concentration data were used, obtained from satellite observations with SeaWiFS and MODIS-Aqua/Terra instruments in the Black Sea for 1998–2015. The role of macro- and microcirculations in the spatial and temporal variability of phytoplankton biomass is estimated. A gain in wind activity and a drop in water temperature from October to March, which lead to an increase in the depth of the mixed upper layer and the intensity of the main synoptic circulations, become a significant factor promoting winter–spring phytoplankton bloom. As revealed, a decrease in the mean water temperature in the cold season to +7…+8 °C, lasting for more than six weeks in the deep-water zone, leads to the intensive biomass development in spring. It was established that the mean phytoplankton biomass for 18 years in the western and eastern cyclonic cycles is (38.0 ± 17.8) and (37.7 ± 16.8) mg C·m⁻³, respectively, and in the Batumi anticyclone, (38.2 ± 18.0) mg C·m⁻³. As a rule, the Rim Current carries phytoplankton formed at the shelf zone along the coastline and almost does not mix with deep waters. In the cyclonic cycles, winter–spring phytoplankton bloom is observed on average for six weeks. Intensive bloom in the area of the flow of northwestern rivers, recorded in May–June, extends to the Bosporus, while in the cold season, it can penetrate into the deep-sea area in the form of micro-eddies. In winter and spring, the Sevastopol anticyclonic eddy stood out as a separate zone in terms of biomass development. The role of anthropogenic load is most significant in the coastal zone. However, the effect of coastal waters on the deep-sea area is possible in late autumn and winter.

Using the vertical sounding method for recording bioluminescence in the Antarctic sector of the Atlantic Ocean

2023-09-05T07:53:13+00:00

Bioluminescence is an essential element in the functioning of the pelagic community, which is associated with the key ecological role of light in the life of hydrobionts, inter alia in the formation of their spatial heterogeneity. The luminescence of marine hydrobionts is a manifestation of their vital activity in the form of electromagnetic radiation in the spectrum visible area, and its kinetic patterns are closely related to mechanism generating their chemical reactions and metabolic processes. Global warming, which undoubtedly has affected the Atlantic sector of Antarctica, caused serious structural and functional alterations in the pelagic community with repercussion on marine bioluminescence, an expressive indicator of environmental conditions. We aimed at studying the possibility of using the method of multiple vertical sounding by the hydrobiophysical complex “Salpa-M,” with simultaneous capture of biophysical and hydrological parameters at one station, to investigate the structure and length of fields of luminescence in Antarctic waters. The paper provides the technique for analyzing structural characteristics of bioluminescence, as well as material obtained during the 79^th Antarctic expedition onboard the RV “Akademik Mstislav Keldysh.” The core of the sounding method is raising (or lowering) the bathyphotometer “Salpa-M” at a constant speed in a given layer [usually, it is the upper productive (0–200 m) or the photic (0–100 m) layer] in the RV’s drift. Planktonic bioluminescent organisms, which are the main contributors to the formation of the bioluminescent potential of the pelagial, mostly illuminate when stimulated. Therefore, a bathyphotometer moving at a constant speed creates a standard level of the mechanical stimulation of bioluminescent organisms, and this allows to compare correctly the results of measurements for the vertical structure of the field of bioluminescence carried out in different areas and under various weather conditions (rolling, wind drift, etc.). The paper presents a fairly large data set of the integral bioluminescent signal at different horizons. Primary data on bioluminescence intensity, temperature values, electrical conductivity, and photosynthetically active radiation were obtained at 18 hydrographic stations in the studied water area of the Atlantic sector of Antarctica. The article considers an important issue related to the change in seawater bioluminescence in the Atlantic sector of Antarctica studied by the vertical sounding at different levels with a bioluminescent probe. When investigating bioluminescence, its vertical variability in the upper productive layer was determined in relation to features of plankton distribution. As a result, it was found out that the luminescence of Antarctic waters in the photic layer of this area occurs within the range from 8.4 × 10⁻¹² to 104.42 × 10⁻¹² W·cm⁻²·L⁻¹. Bioluminescence peaks (up to 104 × 10⁻¹² W·cm⁻²·L⁻¹) were recorded under the thermocline at a 45-m depth in the areas of concentration of the salp Salpa thompsoni Foxton, 1961 near the hydrological front, at a distance of about 6–7 miles on either its side. It is shown that the method of vertical sounding in Antarctic waters allows expressing the fields and the structure of aggregations of luminescent organisms.

The structure of coastal ichthyoplankton in the area of the Dudinka River confluence (Eastern Sakhalin)

2023-09-05T08:11:40+00:00

The structure of ichthyoplankton complex and features of early fish ontogeny were analyzed in the coastal area off the Eastern Sakhalin. The study area is characterized by strong variations of temperature and salinity in May–July. Minimum temperature (+0.4 °C) was registered at a depth of 20 m in May, and maximum one (+15.7 °C) was recorded at a depth of 3 m in September. During the entire study period, salinity varied from 3.5 PSU in littoral zone close to the Dudinka River mouth to 31 PSU at a depth of 13–20 m. Eggs and larvae of 17 fish species from 5 families, typical for the Eastern Sakhalin, were identified in ichthyoplankton. Pleuronectidae species prevailed in taxonomic list with ratio of 71%. Gadus chalcogrammus eggs and larvae (71% of total value) prevailed in the second decade of May; Clupea pallasii bottom eggs (70%), in the third decade of May; and Pleuronectidae eggs and larvae (91–100%), in June–September. Mean ichthyoplankton abundance decreased from 52 ind.·m⁻³ in littoral zone to 21–22 ind.·m⁻³ above depths of 5–10 m and 13 ind.·m⁻³ above 20 m. The proportion of dead G. chalcogrammus eggs and Pleuronectidae eggs did not exceed the values obtained for the Northeastern Sakhalin and was lower than in Aniva Bay. In May, the proportion of G. chalcogrammus and Hippoglossoides robustus prelarvae with pathologies increased. It could be caused by the development of eggs at late stages in adverse conditions. Maximum species diversity was observed in June. Seventy-seven percent of cumulative abundance was composed by eggs of four species, G. chalcogrammus, H. robustus, Myzopsetta punctatissima, and Limanda aspera.

Assessment of radiation effect of 137Cs, 134Cs, and 90Sr on biota of the Barents Sea in the vicinity of hypothetical accident with the sunken nuclear submarine K-159

2023-09-05T08:04:25+00:00

Radiation effect of ¹³⁷Cs, ¹³⁴Cs, and ⁹⁰Sr on marine biota was modelled for early period of a hypothetical accident with the sunken nuclear submarine K-159 during its surfacing and transportation in the Barents Sea. Dynamics of radioactivity in seawater was described, using analytical 2-dimensional model of radionuclide dispersion from an instantaneous point release in seawater. Radioactive contamination of seawater and bottom sediments with ¹³⁷Cs, ¹³⁴Cs, and ⁹⁰Sr was calculated for distances from 200 m to 30 km from the source. Estimated dose of acute exposure accumulated within the first 10 days was close to 100 mGy for bottom fish at a 200-m distance from the accidental source of contamination. The probability of lethal effects for fish at this dose was estimated to be below 1%. Chronic exposures from ¹³⁷Cs, ¹³⁴Cs, and ⁹⁰Sr at a distance of 200 m from the accidental source of contamination during the first year after the accident were as follows: for bottom fish, 9.7 mGy·day⁻¹; molluscs, 11 mGy·day⁻¹; and aquatic plants, 6.3 mGy·day⁻¹. These dose rates exceed the reference level ensuring safety of marine biota. Therefore, in the vicinity of the accident site, the radiation situation cannot be considered safe for bottom fish, molluscs, and aquatic plants. At distances of more than 500 m from the accidental source of contamination, expected dose rates of chronic exposure to marine biota were below reference level. Dose rates for biota resulting from a hypothetical accident in the Barents Sea were caused mainly by external exposure from contaminated sediments and also by accumulation of long-lived radionuclides from sediments by bottom biota.

On a large shortfin mako shark Isurus oxyrinchus (Lamnidae) observed at Cabo San Lucas, Mexico (eastern central Pacific Ocean)

2023-09-14T12:54:09+00:00

A large female shortfin mako shark, Isurus oxyrinchus Rafinesque, 1810, was observed on 26 March, 2023, off Cabo San Lucas, Baja California Sur, Mexico. The total length was carefully estimated at 450 cm. This shark is the third largest mako ever recorded and the second largest observed and photographed alive.

Restoration of the Chara aculeolate Kützing phytocenosis in the Tendrovsky Bay (Black Sea)

2023-09-14T12:51:20+00:00

For the Chara aculeolata Kützing phytocenosis in the Tendrovsky Bay of the Black Sea, long-term dynamics of growth areas and biomass of macrophytes was analyzed. Its partial degradation was observed since 1993. In 1993–2010, the area of the phytocenosis decreased from 100 to 6.3 km². In 2010–2021, elements of regenerative succession were registered. A gradual slow expansion of growth areas and an increase in algae biomass were noted over the 10-year monitoring, and a sudden significant recovery was recorded in 2021. According to the data of 2021, the C. aculeolata phytocenosis was distributed over an area of 36 km², and the biomass of the prevailing species reached 1,800 g·m⁻². Possible reasons for the observed changes are discussed.

Finding of Acrosorium yendoi Yamada (Delesseriaceae, Rhodophyta), a new to Kamchatka species, in Avacha Gulf

2023-10-16T08:45:15+00:00

Recent finding of the red alga Acrosorium yendoi, new to Kamchatka, during observations in a laboratory marine aquarium, containing sediments and water from the Avacha Bay (Southeastern Kamchatka), was supported by its discovery in this water area using the method of parallel floristic observations both under laboratory and natural conditions. A. yendoi was previously recorded in more southern areas of the Pacific coast of Russia (Sea of Japan), as well as in Japan, China, and Korea. As a result of our studies, the species is registered in the flora of Eastern Kamchatka, and this significantly expands the understanding of A. yendoi range, shifting it to the north and changing the phytogeographic characteristics of the species.