Heterotrophic bacteria,zooflagellates, and ciliates in coastal waters of northeastern Black Sea

According to the parameters of density and biomass of heterotrophic bacterioplankton, waters in the ports of Novorossiysk and Tuapse were eutrophic-hypereutrophic and in the resort cities of Gelendzhik and Anapa they were hypereutrophic. The abundance of heterotrophic bacteria reached maximum values of 12.7–14.2 million cells/mL during the period of abnormally high water temperatures (August 2010) in recreational zones. Chainlike and filamentous forms (57–65%) of bacteria, which were typical for the strong coastal pollution of waters, prevailed. The abundance of zooflagellates (kinetoplastids) in semi-isolated water areas (port of Novorossiysk and Gelendzhik Bay) reached the level of highly eutrophic waters, 6.2–9.7 million ind/m³. However, the biomass of naked ciliates was 1.5 times lower than their maximum values earlier registered in coastal waters of the northeastern shelf. The peak of abundance of alien tintinnids of the genera Eutintinnus, Tintinnopsis, and Amphorellopsis, which were introduced via ballast waters of ships, was recorded in Novorossiysk Bay. The ratio of titinnids to the total abundance of ciliates increased 5 times and reached 25–40%. Protozoans developed poorly in the oil-polluted port of Tuapse and the open Anapa Bay.     

Ichthyoplankton in the plankton community of the Crimean Peninsula shelf zone (Black Sea) in July 2010

Data on the species composition and quantitative distribution of ichthyoplankton, zooplankton, and jelly fish macroplankton from different areas of the Crimean Peninsula shelf zone in July 2010 are presented. It has been shown that the structure of species composition and the maximum abundance of ichthyoplankton are comparable to those in July 1988, i.e., until negative changes in the ecosystem of the Black Sea shelf, which took place in the 1990s. The average abundance of ichthyoplankton in July 2010 corresponds to the lowest long-term data obtained in July 1950s and 1960s. The effect produced by organochlorine contaminants and by the abundance of jelly fish macroplankton on the survival of pelagic fish eggs and fish larvae is studied. The prevalence of juvenile copepods in the guts of fish larvae, as well as the low proportion of fish larvae with empty stomachs (<10%), if compared to the data obtained in the 1990s (50–90%), point to the favorable trophical conditions for fish larvae in the area of investigation.     

Taxonomic composition and seasonal dynamics of the meroplankton of the coastal zone of the northeastern Black Sea

The composition and dynamics of the numerical density of meroplankton in the Bays and Seaports of the Northeastern Black Sea, viz., Novorossiysk, Tuapse, Gelendzhik, and Anapa were studied in the long-term aspect. The larvae of the benthic invertebrates of 73 taxa were identified. Meroplankton had their peak abundance period from May to September. Larvae of mollusca Mytilus galloprovincialis and Cardiidae gen sp. (Bivalvia) were dominant in the spring; larvae of mollusca Bittium reticulatum (Gastropoda), Mytilaster lineatus were dominant in the summer, and M. galloprovincialis, Anadara cf. inaequivalvis, Chamelea gallina (Bivalvia) were dominant in the autumn. Polychaete and cirriped larvae occurred in the plankton during the spring-autumn season. Complex species that are tolerant to pollution, such as Amphibalanus improvisus, M. lineatus, B. reticulatum, and the genus Polydora were abundant in Novorossiysk and the Tuapse.     

Oithona brevicornis Giesbrecht (Copepoda, Cyclopoida) in harborages of the northeastern part of the Black Sea shelf

Cyclopoid species Oithona brevicornis Giesbrecht, a new species for the Black Sea, was found in zooplankton samples collected in autumn of 2005 and 2006 in the Novorossiysk and Tuapse ports of the northeastern shelf of the Black Sea. This species is assumed to have gotten into the Balck Sea with the ballast waters of ships.     

Exotic flagellates of coastal North Sea waters

Flagellate species have been shown to survive transocean passage by ballast water and the large dinoflagellateGymnodinium catenatum was introduced from Japanese to Tasmanian waters in this way.Gymnodinium mikimotoi—better known asGyrodinium aureolum—andFibrocapsa japonica as well asAlexandrium leeii are good candidates to have been introduced recently. Species which seem to have been introduced recently into the North Sea but apparently are transported from adjacent seas by currents into the region areGymnodinium chlorophorum andAlexandrium minutum. Species reported as introduced due to misidentifications areGymnodinium catenatum andLepidodinium viride. Under other names the speciesProrocentrum minimum, Prorocentrum redfieldii, andHeterosigma akashiwo have been known for a long time in the North Sea. The recent reports of threeChattonella species may be either due to introduction or they have been overlooked. The reasons why the introduction of flagellates into coastal North Sea waters is difficult to prove will be discussed.     

Ichthyoplankton in the plankton community of the western sector of the Black Sea in October 2005

Data on the numbers, species composition, and spatial distribution of ichthyoplankton, mesoplankton, and jelly-bodied microplankton in the western sector of the Black Sea in October 2005 are presented. A decrease in the predatory impact of the comb jellyfish Mnemiopsis leidyi on mesoplankton is recorded, which promoted the formation of favorable trophical conditions for larval fish survival. In the 1990s in the study area, the proportion of larvae with empty stomachs reached 80–90%; in October 2005, all the studied larvae were with food.     

Microbial manganese and sulfate reduction in Black Sea shelf sediments

The microbial ecology of anaerobic carbon oxidation processes was investigated in Black Sea shelf sediments from mid-shelf with well-oxygenated bottom water to the oxic-anoxic chemocline at the shelf-break. At all stations, organic carbon (C(org)) oxidation rates were rapidly attenuated with depth in anoxically incubated sediment. Dissimilatory Mn reduction was the most important terminal electron-accepting process in the active surface layer to a depth of approximately 1 cm, while SO(4)(2-) reduction accounted for the entire C(org) oxidation below. Manganese reduction was supported by moderately high Mn oxide concentrations. A contribution from microbial Fe reduction could not be discerned, and the process was not stimulated by addition of ferrihydrite. Manganese reduction resulted in carbonate precipitation, which complicated the quantification of C(org) oxidation rates. The relative contribution of Mn reduction to C(org) oxidation in the anaerobic incubations was 25 to 73% at the stations with oxic bottom water. In situ, where Mn reduction must compete with oxygen respiration, the contribution of the process will vary in response to fluctuations in bottom water oxygen concentrations. Total bacterial numbers as well as the detection frequency of bacteria with fluorescent in situ hybridization scaled to the mineralization rates. Most-probable-number enumerations yielded up to 10(5) cells of acetate-oxidizing Mn-reducing bacteria (MnRB) cm(-3), while counts of Fe reducers were <10(2) cm(-3). At two stations, organisms affiliated with Arcobacter were the only types identified from 16S rRNA clone libraries from the highest positive MPN dilutions for MnRB. At the third station, a clone type affiliated with Pelobacter was also observed. Our results delineate a niche for dissimilatory Mn-reducing bacteria in sediments with Mn oxide concentrations greater than approximately 10 micromol cm(-3) and indicate that bacteria that are specialized in Mn reduction, rather than known Mn and Fe reducers, are important in this niche.     

Biogeochemical cycle of methane in the northwestern shelf of the Black Sea

Seasonal investigations of methane distribution and rates of its oxidation and generation in the water column and sediments of the Black Sea northwestern shelf were carried out within the framework of the interdisciplinary projects "European River-Ocean Systems" (EROS-2000, EROS-21) and "Biogenic Gases Exchange in the Black Sea" (BigBlack) in August 1995, May 1997, and December 1999. Experiments that involved the addition of 14CH3COONa and 14CO2 to sediment samples showed the main part of methane to be formed from CO2. Maximum values of methane production (up to 559 mumol/(m2 day)) were found in coastal sediments in summer time. In winter and spring, methane production in the same sediments did not exceed 3.6-4.2 mumol/(m2 day). The delta 13C values of methane ranged from -70.7 to -81.8@1000, demonstrating its microbial origin and contradicting the concept of the migration of methane from cold seeps or from the oil fields located at the Black Sea shelf. Experiments that involved the addition of 14CH4 to water and sediment samples showed that a considerable part of methane is oxidized in the upper horizons of bottom sediments and in the water column. Nevertheless, it was found that, in summer, part of methane (from 6.8 to 320 mumol/(m2 day)) arrives in the atmosphere.     

Protist diversity in suboxic and sulfidic waters of the Black Sea

The oxic-anoxic transition zone of the Black Sea comprises a large suboxic zone as well as anoxic and sulfidic waters. While the prokaryotes and biogeochemical cycles that characterize this zone have been frequently studied, little is known about the diversity or ecology of its microbial eukaryotes. Here, we present the first broad qualitative report of the protist species composition in the Black Sea redoxcline using molecular tools. Fingerprint analysis from the whole redoxcline revealed a complex community structure of metabolically active protists with distinct shifts along the redox gradient. Additionally, 18S rRNA gene clone libraries were used to compare protist species composition of suboxic and sulfidic water layers. Among the ciliates, sequences related to Pleuronema and Strombidium were dominant in both water layers whereas sequences affiliated with anaerobic plagiopylids and Cyclidium were detected only in the sulfidic zone. Among the flagellates, mainly stramenopiles (mostly bicosoecids and chrysophytes) occurred throughout the redoxcline. In the sulfidic zone we found stramenopile sequences but also euglenozoans, jakobids and choanoflagellates that were related to clonal sequences from other anoxic marine habitats, thus indicating the existence of globally distributed groups of anoxic flagellates. Higher species diversity in the sulfidic zone and about twice as many novel sequence types of ciliates and stramenopiles compared with the suboxic layer emphasizes the importance of anoxic, sulfidic waters as habitat for high protist diversity although the function of these organisms is yet unknown.     

Annual cycle of nanophytoplankton in coastal waters of the Barents Sea

The seasonal dynamics of biomass and size structure of nanophytoplankton in Central Murman (off the southern coast of the Barents Sea) are described according to the results of six-year continuous observations. The pattern of the annual successional cycle indicates that the nanophytoplankton community as a structural unit of coastal pelagic algocenoses is a specific integrated ecological group of primary producers. The issue of a major contribution of nanoalgae to the total biomass and production of the autotrophic component of coastal ecosystems in Arctic seas is discussed.     

Distribution and abundance of fish in the southwest of Caspian Sea coastal waters

This study was carried out in southwestern Caspian Sea coastal area to elucidate demersal bony fishes distribution and abundance. Twenty two species were found in shore line, which belong to 6 families. In deeper waters down to 7 meters only 5 species of Gobiidae and 1 species of Syngnathidae were identified. Two species Neogobius caspius and N. pallasi were the main components of demersal fishes; however in some regions Rutilus caspicus, Rutilus kutum and Liza spp. were dominated. Most places were dominantly occupied by Atherina boyeri, which had the highest abundance among the pelagic fishes. Conversely, the Ponticola gorlap, N. melanostomus and Proterorhinus nasalis showed the lowest abundances (less than 1 ind./100 m²). Benthophilus stellatus and P. nasali had the lowest niche overlaps with other species. Both of these two species and P. gorlap are suggested to be classified as endangered or vulnerable species based on their low abundance. The distribution of Syngnathus abaster depends on algae, while algae grow up into the stony construction of the coastal line. A negative insignificant correlation was observed between pelagic and demersal fish abundances. The commercial fisheries data of 76 beach seines in our study area during 2002–2013 was compared with our results on fish abundance and species composition. More than 93% of total fish catch constituted Liza spp. and Rutilus kutum. The relationship between the abundance and distribution of the studied species, and the restocking activities performed by Iranian fisheries organization are discussed. The high abundance and distribution of small size fish in tidal zone could be related to the distribution of crustacean, which provide a good source of food for these fish species.     

Enrichment of omnivorous cercozoan nanoflagellates from coastal Baltic Sea waters

Free-living nano-sized flagellates are important bacterivores in aquatic habitats. However, some slightly larger forms can also be omnivorous, i.e., forage upon both bacterial and eukaryotic resources. This hitherto largely ignored feeding mode may have pronounced implications for the interpretation of experiments about protistan bacterivory. We followed the response of an uncultured group of omnivorous cercozoan nanoflagellates from the Novel Clade 2 (Cerc_BAL02) to experimental food web manipulation in samples from the Gulf of Gdańsk (Southern Baltic Sea). Seawater was either prefiltered through 5 μm filters to exclude larger predators of nanoflagellates (F-treatment), or prefiltered and subsequently 1∶10 diluted with sterile seawater (F+D-treatment) to stimulate the growth of both, flagellates and bacteria. Initially, Cerc_BAL02 were rapidly enriched under both conditions. They foraged on both, eukaryotic prey and bacteria, and were highly competitive at low concentrations of food. However, these omnivores were later only successful in the F+D treatment, where they eventually represented almost one fifth of all aplastidic nanoflagellates. By contrast, their numbers stagnated in the F-treatment, possibly due to top-down control by a concomitant bloom of other, unidentified flagellates. In analogy with observations about the enrichment of opportunistically growing bacteria in comparable experimental setups we suggest that the low numbers of omnivorous Cerc_Bal02 flagellates in waters of the Gulf of Gdańsk might also be related to their vulnerability to grazing pressure.     

Polychaeta (Annelida) associated with Thalassia testudinum in the northeastern coastal waters of Venezuela

Seasonal variations of polychaetes in a Thalassia testudinum bed were studied from June 2000 to April 2001 in Chacopata, northeastern Venezuela. Eight replicate samples were taken monthly with a 15 cm diameter core and the sediment was passed through a 0.5 mm mesh sieve. A total of 1,013 specimens, belonging to 35 species, was collected. The monthly density ranged from 387 ind/m2 (September) to 1,735 ind/m2 in May (x = 989+/-449 ind/m2). Species richness was lowest in August and September (8) and highest (25) in April (x = 18.00+/-5.29). The shoot density of Thalassia showed an average of 284+/-77.60 shoots/m2, with extreme values in February (164) and May (422). Species diversity ranged from 1.25 in August and 3.33 bits/ind in December (x = 2.47+/-0.64). Significant positive correlations were detected among the number of Thalassia shoots, polychaete abundance and species richness, as well as among species richness, polychaete abundance and species diversity. Species number and average density were found within the intervals of mean values reported in similar studies. The higher number of species and organisms obtained in March-April and June-July can be attributed to the recruitment correlated with the regional up-welling.     

Spatial distribution and diversity of commercial demersal fish species in the shelf waters of the Caspian Sea

The Caspian Sea (CS) is a unique ecosystem known for its several fish species, especially sturgeons. To exhaustively manage the fish stocks of this ecosystem, detailed knowledge of species composition, abundance, distribution, and the habitat traits of the living organisms is necessary. This study analyzed the diversity, spatial, and seasonal distribution of commercial demersal fish species, and examined the relationships between community structure and environmental variability in Iranian shelf waters of the CS. For this purpose, seasonally fish sampling took place between 2009 and 2011 with a bottom trawl. Among 11 fish species captured, Chelon spp., Rutilus kutum, and Vimba vimba showed the highest abundances (i.e. 88.49%, 10.67%, and 0.69%, respectively). Univariate and multivariate analyses showed differences in commercial fish assemblages (abundance and species richness) according to seasons and regions. Distance-based Linear Model (DisTLM) showed that eight environmental variables display significant linear relationships with the fauna resemblance matrix (p < .05). Based on AIC criteria, the combination of silt&clay, TOM, longitude, depth, bottom, and surface temperature used to build the parsimonious DisTLM model explain 67.03% of the total variability. The results revealed a biogeographical and temporal gradient from the west to the east and summer to winter, in terms of commercial demersal fish assemblages and species diversity, as a consequence of different geomorphological, bottom substratum conditions and benthic communities.     

The chemical character and burial of phosphorus in shallow coastal sediments in the northeastern Baltic Sea

The chemical composition and vertical distribution of sediment phosphorus (P) in shallow coastal sediments of the northeastern Baltic Sea (BS) were characterized by sequential extraction. Different P forms were related to chemical and physical properties of the sediments and the chemistry of pore water and near-bottom water. Sediment P composition varied among the sampling sites located in the Archipelago Sea (AS) and along the northern coast of the Gulf of Finland (GoF): the organic rich sites were high in organic P (OP), while apatite-P dominated in the area affected by sediment transportation. Although the near-bottom water was oxic, the sediments released P. Release of P was most pronounced at the site with high sediment OP and reduced conditions in the sediment-water interface, indicating that P had its origins in organic sources as well as in reducible iron (Fe) oxyhydroxides. The results suggest that even though these coastal areas are shallow enough to lack salinity stratification typical for the brackish BS, they are vulnerable to seasonal oxygen (O₂) depletion and P release because of their patchy bottom topography, which restricts mixing of water. Furthermore, coastal basins accumulate organic matter (OM) and OP, degradation of which further diminishes O₂ and creates the potential for P release from the sediment. In these conditions, an abundance of labile OP may cause marked efflux of P from sediment reserves in the long-term.     

A 5-year study of the influence of the northeast and southwest monsoons on copepod assemblages in the boundary coastal waters between the East China Sea and the Taiwan Strait

Danshuei River in the northwestern tip of Taiwan dischargesinto the boundary coastal waters between the East China Seaand the Taiwan Strait. We conducted a 5-year study between October1998 and September 2003 to assess the influence of the northeast(NE) and the southwest (SW) monsoons on copepod assemblagesin the area. A total of 110 copepod species were identified.Temora turbinata, Paracalanus aculeatus, Acrocalanus gibber,Parvocalanus crassirostris and Oithona rigida comprised 80%of the copepod assemblages that consisted of coastal speciesfrom the East China Sea and species associated with the KuroshioBranch Current. The effect of the NE monsoon was observed duringa short period of each winter when species such as Calanus sinicuswere transported into the study area by the China Coastal Current.In summer, species such as A. gibber, Acrocalanus gracilis andCanthocalanus pauper may be transported into the study areafrom Southern Taiwan by the combined effect of the SW monsoonand the Kuroshio Current. Influence of the NE monsoon on thecopepod assemblages in terms of introduction of species fromthe Yellow Sea and the East China Sea during winter was observedevery year but was unlikely to represent an important carbonsource into the region due to its short-term nature. Local speciessuch as T. turbinata, P. crassirostris and O. rigida form amajor component of the copepod assemblage. The high copepoddiversity in the area was caused by the year-round presenceof many local species and the aggregation of different speciesfrom subtropical, tropical, and temperate water masses. Monsoon-drivenwater currents and the Kuroshio Branch Current appeared to maskthe effect of river discharge in the region.