Southeastern Black Sea Research Articles

Seasonal changes in abundance, lipid and fatty acid composition of Calanus euxinus in the South-eastern Black Sea

Seasonal changes in abundance, lipid and fatty acid composition of Calanus euxinus Hulsemann, 1991 were analysed monthly during the period from March 2012 to February 2013. The highest abundance of C. euxinus was recorded in February (847 ind. m-3) during the sampling period. Female and male C. euxinus peaked in February (587 ind. m3, 169 ind. m-3, respectively). However, copepodites peaked in November (107 ind. m-3). Average total lipid content was determined as percentage (%) and per individual (mg ind-1). It was proportionally highest in February (7.03%) and lowest in September (3.02%). However, average lipid content per individual was highest in February (0.11 mg ind-1) and lowest in September and November (0.04 mg ind-1). Major fatty acids in C. euxinus were identified as 16:0, 16:1 n-7, EPA and DHA. ΣSFA, ΣMUFA, ΣPUFA and ΣHUFA were observed to be correlated with temperature. ΣSFA and ΣMUFA increasedwith the rise in temperature (r2=0.74, r2=0.73, p<0.05, respectively) whereas ΣPUFA and ΣHUFA increased as temperature decreased (r2=-0.73, r2=-0.80, respectively, p<0.05). Additionally, while ΣPUFA and ΣHUFA increased (r2=0.61, r2=-0.68, respectively, p<0.05), ΣMUFA decreased (r2=-0.68, p<0.05) as chlorophyll-a increased. It was observed that the degree of unsaturation increased as temperature decreased. Results of the study revealed that C. euxinus has rich lipid content as well as fatty acid composition and it plays an important role in the South-eastern Black Sea ecosystem functionalities especially having key role in energy fluxes to higher trophic levels.

Pollution Assessment of Toxic Metals in Representative Limnetic Ecosystem Sediments in the Southeastern Black Sea, Turkey

In this study, the natural and anthropogenic toxic metal pollution, and the general characteristics of lake sediments are investigated spatially and temporally. Three lakes are chosen in 2014 according to their origin from the Southeastern Black Sea‐Sera Lake, Uzungol Lake, and Borçka Dam Lake. Four sampling campaigns are conducted during the four seasons: spring, autumn, winter, and summer. The elements lead (Pb), copper (Cu), zinc (Zn), nickel (Ni), and arsenic (As) are selected for investigation. The highest average toxic concentrations of Cu (498.46 μg g−1), Pb (185.60 μg g−1), and As (18.74 μg g−1) were found in Borçka Dam Lake; however, those of Zn (435.00 μg g−1) and Ni (143.42 μg g−1) are found in Sera Lake. The highest metal concentrations are observed in autumn. Metal concentrations are determined by inductively coupled plasma mass spectrometry. The potential ecological risk index (RI) and geoaccumulation index (IGEO) values are calculated for assessing sediment pollution. The assessment of sediments according to their potential ecological risk to the aquatic environment reveal that Cu contamination is a moderate risk in Borçka Dam Lake. According to IGEO classifications, the highest IGEO values are found in Borçka Dam Lake in autumn. Accordingly, the study area is determined to be highly contaminated with Cu and Pb. Cu and Pb can be considered as major contributors to ecological risk in these Southeastern Black Sea lakes.

Seasonal and spatial variations of marine litter on the south-eastern Black Sea coast

The south-eastern Black Sea coast in Turkey was evaluated for marine litter composition and density covering nine beaches during four seasons. The marine litter (>2cm in size), was collected from the coast and categorized into material and usage categories. The data analysis showed that plastic was the most abundant litter (≥61.65%) by count and weight followed by styrofoam and fabric. The marine litter density ranged from 0.03 to 0.58 with a mean (±SD) of 0.16±0.02 items/m2 by count. Based on weight, it varied between 0.44 and 14.74g/m2 with 3.35±1.63. The east side had a higher marine litter density than the west side with significant differences between beaches. The variations due to different seasons were not significant for any beach. The results of this study should provide baseline information about the coastal marine pollution and will assist the mitigation strategies.

Spatio-temporal pattern of phytoplankton and pigment composition in surface waters of south-eastern Black Sea

Phytoplankton community, diatom to dinoflagellate ratio and pigment composition in surface waters with nutrient data from April 2013 to March 2014 were monitored in the south-eastern (SE) Black Sea using high performance liquid chromatography (HPLC) and microscopic analyses. Microscopic examination revealed a total of 71 species that consist of dinoflagellate (58%), diatoms (25%) and other groups (17%). Microscopy and HPLC-based pigment analyses revealed almost similar results which suggest that the phytoplankton community is mainly composed of diatoms, dinoflagellates and coccolithophores. Fucoxanthin (mean 0.35 ± 019 μg L−1), peridinin (mean 0.18 ± 0.14 μg L−1) and 19-hexanoyloxyfucoxanthin (mean 0.24 ± 0.15 μg L−1) are prominent pigments which showed significant correlation with Diatom-C (r2 = 0.63–0.71, p < 0.05), Dinoflagellate-C (r2 = 0.49–0.80, p < 0.05) and Coccolithophore-C (r2 = 0.72–0.82, p < 0.05), respectively. Mean carbon biomass of diatoms (36.50 ± 9.72 μg L−1) was higher than that of dinoflagellates (33.32 ± 9.05 μg L−1). Significant differences were also observed in nutrient ratio (N:P and Si:N) (One-way ANOVA, p < 0.05). Results illustrate that HPLC-based pigment approach can be used for taxonomic characterisation of phytoplankton groups in the SE Black Sea. Moreover, relatively high dinoflagellate species dominancy and significant correlations between Phyto-C and marker pigments indicate that phytoplankton community composition is shifting towards much smaller groups in SE coasts of the Black Sea.

Seasonal Changes in Phytoplankton Size Classes (PSC) Derived From HPLC Pigment Data along the South-Eastern Black Sea

Seasonal Changes in Phytoplankton Size Classes (PSC) Derived From HPLC Pigment Data along the South-Eastern Black Sea

Stock enhancement by hatchery-released turbot, &lt;em&gt;Psetta maxima&lt;/em&gt;, in the southeastern Black Sea: capture, migration, growth and diet analyses

In this study, the capture, growth, migration and diet of hatchery-released turbots (Psetta maxima) were examined in the southeastern Black Sea region for six years (2009-2014). A total of 9933 turbots were marked with individual serial-numbered T-bar anchor tags and released at Trabzon, Turkey. The mean TL and weight of the released turbots were 12.91 cm (±1.25) and 35.41 g (±12.38) and the same measurements for the captured turbots were 31.17±0.86 cm and 878.08±69.47 g, respectively. A total of 2.7% (270 fishes) of the tagged individuals were captured during the study period and the age of the captured tagged fishes was between 0+ and 5+ years. Growth of the captured turbots was analytically examined. Movements of the tagged turbots were expressed as “resident” and “migratory”. Three prey groups showed the majority of forage organisms; teleost fishes, crustaceans and mollusks in the stomach of the captured turbots. The hatchery-released turbots might be used for stock enhancement due to their high growth rate and commercial value, and their relatively limited migration range.

Photobacterium damselae subsp. damselae, an Emerging Fish Pathogen in the Black Sea: Evidence of a Multiclonal Origin.

Photobacterium damselae subsp. damselae is considered to be an emerging pathogen of marine fish of importance in aquaculture, with a notable increase in its geographical distribution during the last several years. In this study, we carried out for the first time to our knowledge a genetic and pathobiological characterization of 14 strains isolated from sea bass (Dicentrarchus labrax) reared in the Southeastern Black Sea, where high mortalities were observed at two aquaculture farms during the summer and autumn of 2011. Heterogeneity was evidenced among strains in phenotypical traits, such as sucrose fermentation, motility, and hemolysis. Although 11 of 14 isolates were hemolytic, we found that all of the isolates lacked the pPHDD1 virulence plasmid that encodes the phospholipase-D damselysin (Dly) and the pore-forming toxin PhlyP, two hemolysins previously reported to constitute major virulence factors for turbot. Subsequent PCR and sequencing analyses demonstrated that the 11 hemolytic isolates harbored a complete hlyAch gene, a chromosome I-borne gene that encodes HlyAch hemolysin, whereas the three nonhemolytic isolates contained hlyAch pseudogenes caused by insertion sequence elements. Virulence challenges with two representative strains revealed that, albeit less virulent than the pPHDD1-harboring strain RM-71, the plasmidless hlyAch-positive and hlyAch-negative Black Sea isolates were pathogenic for sea bass. A phylogenetic analysis based on the toxR gene sequence uncovered a greater diversity in the isolates, indicating that the presence of this pathogen in the Black Sea was not caused by the introduction and spread of a single virulent clone but by the proliferation of different clones. The geographical distribution of marine bacterial pathogens is undergoing a worldwide increase. In particular, bacteria of the group vibrios are increasingly being isolated as the causative agents of disease in novel species of cultivated fish in areas where they had not been previously reported. Here we characterize for the first time to our knowledge a collection of isolates of the fish and human pathogen Photobacterium damselae subsp. damselae from diseased sea bass reared in the Black Sea. We uncovered great genetic diversity in the Black Sea isolates of this pathogen, suggesting a multiclonal origin. We also demonstrate for the first time that these isolates bear pathogenic potential for sea bass cultures by virulence challenges.

Northern hemisphere climate control on the environmental dynamics in the glacial Black Sea “Lake”

The Marine Isotope Stage (MIS) 3 stands out due to its abrupt changes from cold and dry stadials to warm and humid interstadials, the so-called Dansgaard-Oeschger cycles that also affected temperature and rainfall in the Black Sea region. This study is based on a gravity core from the southeastern (SE) Black Sea that covers the last glacial lake stage from 64 to 20 ka BP. By using the composition of major and trace elements in the sediments, terrestrial plant-derived n-alkane flux, and Sr/Ca from benthic ostracods, we reconstruct the variability of riverine and aeolian input, salinity, and productivity in the SE Black Sea region in response to the Northern Hemisphere climate oscillations. During colder and drier stadials, the aeolian input increased relative to the riverine discharge, potentially due to southward shifted and/or stronger westerly winds and due to changes in the vegetation cover. An evaporation exceeding freshwater supply by rainfall and rivers possibly caused higher salinity and a lower lake level. The environmental status during MIS 4 and 2 is very much comparable with the stadial conditions during MIS 3. During warmer and more humid interstadials, lower salinity and presumably positive lake level changes most likely resulted from increased precipitation and river discharge. This likely increased primary productivity through an augmented nutrient supply. Lowest average salinities are suggested for the middle part of MIS 3 in response to enhanced meltwater from the disintegrating Fennoscandian Ice Sheet and/or by generally more humid conditions.

Crucible technologies in the Late Bronze–Early Iron Age South Caucasus: copper processing, tin bronze production, and the possibility of local tin ores

The South Caucasus was a major center of metal production in the Late Bronze and Early Iron Ages. Nowhere is this more clear than in the hills and mountains in the southeastern Black Sea region (ancient Colchis), where exceptionally large numbers of metal production sites have been found. Chemical and microscopic analysis of slagged technical ceramics at these sites illuminates several aspects of both raw copper and tin bronze alloy production. Copper ores were smelted in a complex multi-stage process designed to extract metal from sulfide ores. Technical ceramics served as containers for a range of different reactions, from the first phase of smelting, in which the copper sulfides were likely consolidated into a matte, though later stages of matte processing and metal copper production in smaller crucibles. In addition, a single crucible fragment, recovered from a late 2nd millennium BC slag heap, demonstrates that tin bronze was created by the direct addition of cassiterite tin ore, probably of alluvial origin, to metallic copper. The crucible's context, the use of cassiterite ore rather than tin metal, and a review of local geology suggests that the tin used in this crucible came from nearby, with the most likely source being the Vakijvari and Bzhuzhi gorges roughly 10–15 km away. While a single fragment does not speak to the regularity of this practice, at the very least it raises the possibility that the Colchian bronze industry was based on local rather than imported tin.

Metal Pollution Assessment in Sediments of the Southeastern Black Sea Coast of Turkey

The main objective of this investigation is to determine the concentration and accumulation of heavy metals in the coastal sediments of the Southeastern Black Sea of Turkey. The selected sampling area has mainly been affected by anthropogenic activities, such as agricultural, untreated domestic and treated industrial wastewater, and mining. Metal enrichment factor (EF), geo-accumulation index (Igeo), and metal pollution index (MPI) have been calculated and relative contamination levels evaluated at all stations. In this study, the maximum EF values calculated for nickel (Ni), cobalt (Co), cadmium (Cd), lead (Pb), chromium (Cr), arsenic (As), zinc (Zn), and copper (Cu) were 1.4, 3.1, 5.2, 7.8, 7.8, 20, 26, and 42, respectively. Metal pollution has decreased in recent years, but the enrichment of heavy metals has been observed to be relatively high, especially in the uppermost 3-6 cm of the core sample from the Sürmene sampling station, which has been polluted by mining activities. In addition, factor analysis revealed that the coastal sediments from the Eastern Black Sea were influenced by several sources, namely lithogenic and anthropogenic activities (mining, wastewater discharging, agriculture).

Establishing Boundary Classes for the Quality Classification of Southeastern Black Sea Using Phytoplankton Biomass

Establishing Boundary Classes for the Quality Classification of Southeastern Black Sea Using Phytoplankton Biomass

WATER RUNOFF, SEDIMENT TRANSPORT AND RELATED IMPACTS IN THE SOUTHEASTERN BLACK SEA RIVERS

WATER RUNOFF, SEDIMENT TRANSPORT AND RELATED IMPACTS IN THE SOUTHEASTERN BLACK SEA RIVERS

The isolation frequency of bacterial pathogens from sea bass (Dicentrarchus labrax) in the Southeastern Black Sea

Abstract To determine occurrence, diversity and frequency of bacterial pathogens in cultured sea bass (Dicentrarchus labrax) using 16S rDNA and biochemical tests. Four hundred seventy-seven sea bass from two distinct farms in the Black Sea were submitted to bacteriological profiling. We often isolated multiple bacterial species in fish, cages and farms during the testing period. Using 16S rDNA sequences and biochemical profiles, 6 species of bacteria were identified and all had different susceptibility to a range of antibiotics. Aeromonas veronii biovar sobria (65.2%) and Photobacterium damselae subsp. damselae (19.1%) were the most frequently isolated species, followed by Vibrio vulnificus (6.7%), V. harveyi (6.7%) and V. rotiferianus (3.3%). Furthermore, elevated monogenean ectoparasite (Diplectanum aequans) load correlated with a higher incidence of bacterial infection. These results are in accordance with the hypothesis that the highly eutrophic environment of the Black Sea supports rich diversity of bacteria in fish and the environment. To our knowledge, this is the first report of A. veronii and V. rotiferianus in sea bass. Our findings also suggest that D. aequans increases the susceptibility of sea bass to bacterial infection. The accurate identification and profiling of bacterial species are essential to manage the mortality of cultured sea bass. Using bacteriological profiling we have identified the most common bacteria found in fish and their susceptibility to a range of antibiotics. These results will help guide the selection and use of antibiotics and vaccines to manage disease outbreaks in cultured fish.

Phytoplankton community composition in the south-eastern Black Sea determined with pigments measured by HPLC-CHEMTAX analyses and microscopy cell counts

The phytoplankton community structure and abundance in the south-eastern Black Sea was measured from February to December 2009 using and comparing high performance liquid chromatography pigment and microscopy analyses. The phytoplankton community was characterized by diatoms, dinoflagellates and coccolithophores, as revealed by both techniques. Fucoxanthin, diadinoxanthin, peridinin and 19′-hexanoyloxyfucoxanthin were the main accessory pigments showing significant correlation with diatom-Cr2 = 0.56–0.71,P &lt; 0.05), diatom-C (r2 = 0.85–0.91,P &lt; 0.001), dinoflagellate-C (r2 = 0.39–0.88,P &lt; 0.05) and coccolithophore-C (r2 = 0.80–0.71,P &lt; 0.05), respectively. Microscopy counts indicated a total of 89 species, 71% of which were dinoflagellates, 23% were diatoms and 6% other species (mainly coccolithophores). Pigment-CHEMTAX analysis also indicated the presence of pico- and nanoplankton. Phytoplankton carbon (phyto-C) concentrations were highest in the upper water column, whereas chlorophyll-a (Chl-a) showedadeep maximum. Average phyto-C was higher at the coastal station (291 ± 66 µg l−1) than at the offshore station (258 ± 35 µg l−1), not statistically different (P &gt; 0.05). The coastal station also had higher Chl-aconcentrations (0.52–3.83 µg l−1) compared to the offshore station (0.63–2.55 µg l−1), not significant (P &gt; 0.05). Our results are consistent with other studies and indicate that the southern Black Sea is shifting towards mesotrophy with the increasing prevalence of dinoflagellates compared to diatoms.

The impact assessment of cage aquaculture on benthic communities along the south eastern Black Sea

The present study was conducted to examine the impact of cage aquaculture on benthic communities in coastal areas (depth 25 to 50 m) from fish farming operations located along the southeastern Black Sea (Ordu-Persembe, Trabzon-Yomra and Rize central). Sampling was conducted seasonally from April 2007 to 2009. Sediment samples were taken using Ekman Grab (box core- 0.04 m 2 ). Temperature, salinity, and water velocity were periodically measured to determine influencing sedimentary organic matter in the sediment, oxygenation, and anoxic conditions. In addition, grain size of sediment, organic carbon content, and distribution of benthic communities were investigated. In order to determine benthic impact of fish farms on the region, Shannon – Wiener diversity index (H’), AMBI (AZTI Marine Biotic Index) and M-AMBI (Multivariate- Marine Biotic Index) indices were used. Results of current study showed that benthic zone ecological quality of stations with number 01, 02, 03, and 04 at Ordu-Persembefish-farming habitat was found to be very low. In autumn 2008, there were 3 species which belonged to Capitella capitata (844 individuals/m 2 ), Capitella sp. (133 individuals/m 2 ), and Heteromastus filliformis (311 individuals/m 2 ) at OP-01 station. In addition, the impact of Trabzon-Yomra fish-farming activity on benthic communities was low. The degree of exposure for Rize fish-farming area in all seasons was quite low, which was not a significant negative impact.

Biological parameters and feeding behaviour of invasive whelk Rapana venosa Valenciennes, 1846 in the south-eastern Black Sea of Turkey

Objective: To determine length-weight relationships, growth type and feeding behavior of the benthic predator Rapa whelk at the coast of Camburnu, south-eastern Black Sea. Methods: Rapa whelk was monthly collected by dredge sampling on the south-eastern Black Sea at 20 m depth. The relationships between morphometric parameters of Rapa whelk were described by linear and exponential models. The allometric growth of each variable relative to shell length (SL) was calculated from the function Y=aSL b or logY=loga+blogSL. The functional regression b values were tested by t-test at the 0.05 significance level if it was significantly different from isometric growth. The total time spent on feeding either on mussel tissue or live mussels was recorded for each individual under controlled conditions in laboratory. Results: The length-weight relationships showed positive allometric growth and no inter-sex variability. Body size in the male population was significantly higher than in the individuals of the female. All characters in males and females showed a trend towards allometry rather than isometry. While the total time spent feeding increased with increasing prey size the total time that Rapana venosa spent feeding decreased with increasing Rapa whelk size. The total average feeding time needed by Rapa whelks was 160 min. But they took 310 min on live mussels in 27-28 °C in the laboratory conditions. Conclusions: Length and weight relationships, growth type, total time spent feeding of this species were explained in details for this region. It would be useful to sustainable management in the south-eastern Black Sea of Turkey. The results about the feeding behaviour of this species will contribute to the understanding of the role of this species within the ecosystem.

Survey of viral haemorrhagic septicaemia virus in wild fishes in the southeastern Black Sea.

Species diversity in the Black Sea ecosystem has been declining rapidly over the last 2 decades. To assess the occurrence and distribution of viral haemorrhagic septicaemia virus (VHSV) in various wild fish species, a wild marine fish survey was carried out in 2009, 2010, and 2011. The pooled or individual samples of kidney, liver, and spleen of 5025 specimens, belonging to 17 fish species, were examined virologically using cell culture. The cells showing cytopathic effects (CPE) were subjected to ELISA and multiplex reverse transcriptase polymerase chain reaction (RT-mPCR), for VHSV and infectious pancreatic necrosis virus (IPNV), after blind passaging to determine the virus species causing CPE. The virus species and possibility of co-infection with IPNV were verified by the RT-mPCR developed in this study. Twelve species of fish (pontic shad Alosa immaculata, red mullet Mullus barbatus, three-bearded rockling Gaidropsarus vulgaris, black scorpionfish Scorpaena porcus, Mediterranean horse mackerel Trachurus mediterraneus, whiting Merlangius merlangus euxinus, stargazer Uranoscopus scaber, pilchard Sardina pilchardus, garfish Belone belone, round goby Neogobius melanostomus, thornback ray Raja clavata, and anchovy Engraulis encrasicolus) tested positive for VHSV Genotype Ie (VHSV-Ie). Except whiting, pilchard, and round goby, the rest are new host records for VHSV. The extent and spread of VHSV-Ie was significantly higher among bottom fish than among pelagic fish. Sensitivity and specificity of the RT-mPCR developed was sufficiently high, suggesting that this assay may be used for both diagnostic and surveillance testing. According to the RT-mPCR results, IPNV was not present in wild fish. These results support the hypothesis that the VHSV-Ie genotype, highly prevalent among fish species in the Black Sea, may have a serious impact on the population dynamics of wild fish stocks.

The relationship between fish size and otolith dimensions of stargazer (Uranoscopus scaber) in the south-eastern Black Sea

Relations between fish size and otolith size of stargazer (Uranoscopus scaber) were studied in this study. A total of 268 samples were obtained from the coastal shelf of Ordu Province (south-eastern Black Sea) by commercial trawling and gillnetting operations. It was found that there were high correlations between fish size and otolith size. It was concluded that all measurable body sizes could be effectively used to estimate otolith length, width and weight. Similarly, estimation of the age of fish from otolith length and weight was also possible with high significance. The results of this research will be useful for others working on this fish, being a first study in the field. The ages of stargazer were determined between 0+ and 4+. Relationships were determined as OW = 0.001 × OWi2.76, OW = 0.35 × 10−3 × OL2.54 with high correlation coefficients of r = 0.965 and r = 0.949, respectively.

Assessment of Heavy Metal Contribution and Associated Ecological Risk in the Coastal Zone Sediments of the Black Sea: Trabzon

AbstractIn this study, the natural and anthropogenic heavy metal (Cu, Pb, Zn, Ni, and Co) pollution in coastal sediments near the city Trabzon which exhibits an increasing population and industrial activity in the Southeastern Black Sea Region, were investigated spatially and temporally. The sediment along the coast of Trabzon is influenced by three rivers, Degirmendere, Yanbolu, and Solakli, resulting in a spatial separation. The highest heavy metal sediment concentrations were measured in the section influenced by Solakli and the lowest at the sites affected by Yanbolu. Furthermore, a strong temporal trend was observed displaying the highest metal concentrations in autumn. With the purpose for determining the level of pollution, the methods of the factor of sediment enrichment factor, the index of pollution load, the index of geoaccumulation and sediment quality guideline were applied. Three research areas were heavily polluted by Cu, Pb, and Zn. These metals concentration in Solakli coastal region were found significant enrichment. Current concentration of these metals would be expected to frequently be associated with toxic effects on biota of coastal regions.

Biological diversity and seasonal variation of mesozooplankton in the southeastern Black Sea coastal ecosystem

In this study, the seasonal distribution of mesozooplankton was investigated between 1999 and 2006 at a station located in the southeastern Black Sea region. A total of 40 cruises were done within the southeastern continental shelf throughout this period in order to collect mesozooplankton samples. A total of 10 mesozooplankton species were identified. The average annual highest abundances of species were 67,770 ind./m2 in 2000 (Penilia avirostris), 50,048 ind./m2 in 2001 (Sagitta setosa), 42,143 ind./m2 in 2006 (Oikopleura dioica), 27,987 ind./m2 in 2005 (Acartia clausi), 25,792 ind./m2 in 2001 (Oithona similis), 24,806 ind./m2 in 2005 (Pseudocalanus elongatus), 12,094 ind./m2 in 2005 (Paracalanus parvus), and 11,697 ind./m2 in 2001 (Calanus euxinus). Calanus euxinus and Pseudocalanus elongatus were determined as cold-water species, having high abundance in winter and early spring. The species of Acartia clausi and Oithona similis were assessed as species observed in all seasons. According to the Bray-Curtis similarity index, the copepod species showed seasonal differences. Summer and early autumn were found to be different from other sampling periods in terms of population structure. The results of this study will form a basis for long-term mesozooplankton monitoring studies in the Black Sea coastal ecosystem.