Southeastern Black Sea Research Articles

Yunuslar ile kıyı balıkçılığı arasındaki etkileşim ve azaltılmasında akustik caydırıcı cihaz kullanımı

This study was conducted at the Unye-Ordu coasts of the South-eastern Black Sea, from May 2015 and February 2017, to investigate the frequency of dolphins-bottom gillnet fisheries interactions, the role of using acoustic deterrent in reducing the damage inflicted by the dolphins to the gillnets and to the fish caught in the gillnets. For this purpose, two gillnet sets with similar technical and equipment characteristics were prepared. While one of the groups had acoustic deterrent (active group), the other did not have acoustic deterrent (control group). In the study were used Future Oceans (70 kHz) deterrent. During the study, in only 3 of the 65 fishing trials have determined the interaction of dolphins with gillnets. It was determined that the number of holes in the gillnets caused by the dolphins was 36.3% less in the nets with acoustic deterrent than the control nets. On the other hand, the CPUE value of the whiting was estimated as 2.01 ± 0.23 kg km-1 s-1 in the gillnets with acoustic deterrent and 1.97 ± 0.24 kg km-1 s-1 in the control nets. These results showed that the use of acoustic deterrent does not have a negative effect on the catch of whiting caught in the gillnets.

A High‐Resolution Paleosecular Variation Record for Marine Isotope Stage 6 From Southeastern Black Sea Sediments

AbstractA full‐vector paleosecular variation (PSV) record (inclination, declination, and relative paleointensity) from the pen‐ultimate glacial (130–180 ka) could be constructed from a total of 12 sediment cores recovered from the Arkhangelsky Ridge in the SE Black Sea. Stacking of the individual partly fragmented records was achieved by a detailed correlation using high‐resolution data records from X‐ray fluorescence scanning, Ca/Ti and K/Ti log‐ratios, as well as magnetic susceptibility. Age constraints are provided by a detailed composite oxygen isotope stratigraphy from three of the cores, correlated to U‐Th‐dated speleothem oxygen isotope records from Hungary and Turkey. The temporal resolution of the stacked paleomagnetic data records is 200 years. Practically, this data set is the first high‐resolution PSV record for SE Europe/SW Asia from marine isotope stage 6, comprising inclination, declination and relative paleointensity. Besides an easterly swing in declination at ∼159 ka and a pronounced intensity low together with low inclinations at ∼148 ka, both not reaching an excursional PSV index of >0.5, the obtained directional variations reflect only normal PSVs, with a PSV index of <0.3.

Basin scale spatiotemporal analysis of shoreline change in the Black Sea

In this study, we carried out a basin-scale long-term shoreline change analysis for the Black Sea coastline. The study consists of 28 subsections with 78943 transects along the coastline. A total number of 96 Landsat satellite images, between 1972 and 2018 are used for the analysis. The average conditions are characterized by erosion with a mean value of shoreline change in the Black Sea of −0.17 m/year, while 23% of the coastline has eroded for more than 1 m/year in the last 40+ years. The results depict that different mechanisms and processes driven by the river sediment loads (e.g. Danube and Kızılırmak Deltas), anthropogenic effects (e.g. Southeastern Black Sea coast of Turkey), and entrapment of coastal sediments are active throughout the coastline and are influencing the long-term shoreline dynamics. It is shown that, at a multi-annual scale, the erosional hotspots are generally located along the low-lying sandy coastal areas of Yeşilırmak, Danube, and Kızılırmak River Deltas, together with the barriers and spits from the Northwestern Crimea and Southwestern Black Sea shores. Hence, 21% of the widest beaches of the Black Sea eroded for more than 1 m/year in the last 40+ years. The total length of the Black Sea coastline is estimated as 4987 km based on the analysis of the most recent satellite images.

Determination of Metal Concentrations in Değirmendere Stream Drainage Area of Southeastern Black Sea Coast of Turkey

Bu çalışmanın amacı Güneydoğu Karadeniz’in Türkiye kıyılarında denize boşalan Değirmendere deresinin drenaj alanında sedimentteki metal derişimlerinin ve zenginleşme düzeylerinin belirlenmesidir. Çalışmada 5 ayrı istasyondan üç arklı mevsimde yüzey sediment örnekleri Ekman Grap kullanılarak alınmıştır. Sedimentteki V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, Al ve Fe derişimleri mikrodalga sistemde çözünürleştirildikten sonra ICP-MS ile ölçülmüştür. Metal derişimleri açısından istasyonlar arasındaki farklılık istatistiksel olarak anlamlı düzeyde değildir (p>0.05). Ancak nehir ağzına yakın konumda bulunan 1 nolu istasyonda bazı metallerin (Fe, Mn, Co, Ni, Cu, Zn, V) derişimleri diğer istasyonlardan nispeten daha yüksek bulunmuştur. Aluminyum normlizasyonu sonucunda tespit edilen zenginleşme düzeyleri V için 1,5-2,1; Cr için 0,6-1,0; Mn için 0,8-1,7; Fe için 1,1-1,7; Co için 1,1-2,0; Ni için 0,4-0,9; Cu için 1,3-2,3; Zn için 1,4-3,9; As için 0,8-1,4; Cd için 0,5-4,1 ve Pb için 0,9-4,2 aralığında bulunmuştur. Bazı istasyonlarda Cu, Zn ve Pb elementlerinin orta derecede zenginleşme gösterdiği tespit edilmiştir.

Toxic Metal Pollution and Ecological Risk Estimation in the Sediment around Hopa Harbor, Turkey (SE)

AbstractThe objective of this article is to determine the spatial changes occurring because of natural and anthropogenic toxic metal pollution in accordance with different indexes using the geographic information system (GIS) method. In this context, the distribution of toxic metals, i.e., chromium (Cr), copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), and arsenic (As), is investigated using sediment samples from the Hopa Harbor situated in the Southeastern Black Sea region. Sediment samples are collected from nine different stations in June 2017. Metal concentrations (in dry weight) vary from 23.2 to 94.7 for Cr, 62.1 to 301.7 for Cu, 89.3 to 287.9 for Zn, 67.6 to 137.1 for Pb, 20.1 to 99.1 for Ni, and 14.2 to 57.4 µg g−1 for As. The samples with highest concentrations are situated in the inner part of the harbor, where the water circulation system to remove the impurities is very poor. It is evident that Hopa Port activities negatively affect sediment quality, with metal concentration values increasing at stations close to the port. The data of this study reveal that Cu, Pb, and As are the main contributors to the ecological toxicity in and around Hopa Harbor. However, if the results are evaluated according to the longer time series, more precise data on the toxic effects of metals can be obtained.

Investigation of the Effects of Hook Size and Bait Type on the Catch of Whiting, Merlangius merlangus (Linnaeus, 1758) (Gadidae) in Bottom Longline Fisheries of the Black Sea

This study was carried out along the Ünye coasts of the South-eastern Black Sea (Turkey), in order to investigate the effects of hook size and bait type on the catch of whiting, Merlangius merlangus (Linnaeus, 1758) (Gadidae) in the bottom longline fisheries. For this, a set of bottom longline with a total of a hundred hooks, including 20 from each hook number 2, 4, 6, 8 and 10, was tested in a total of 24 trials twice a month between March 2017 and February 2018. Each hook type was baited with squid, horse mackerel, chicken breast and whiting. During the study, a total of 373 whiting were caught. Most of the whiting catch was obtained with the hook no 2. With the reduction in hook size, both the amount of catch and the size of the fish caught decreased. Most whiting werecaught by the hooks baited with squid. This was followed by the hooks baited with horse mackerel, chicken breast and whiting, respectively. This result shows that hook size no 2 or larger should be used for catching whiting when using bottom longline in the Ünye coasts of the South-eastern Black Sea. Howev-er, considering the bait types used in this study, it is recommended to use squid as bait. If squid is thought to increase the cost of fishing, alternatively horse mackerel or chicken breast can also be used as bait.

Catch Comparison of Commercial and Experimental Deep Water Cast Nets with Different Mesh Sizes for Whiting (Merlangius merlangus euxinus) Fishery

In the present study, the commercial (16 mm nominal mesh size) and experimental deep water cast nets with different mesh sizes (20 mm, 24 mm, 28 mm and 32 mm nominal mesh size) were tested to compare the captured fish lengths and catch amounts for whiting (Merlangius merlangus euxinus). Experiments were carried out between July, 11 and August, 29, 2018 in Rize province of the south-eastern Black Sea Region. A commercial fishing boat was chartered for 20-day sea trials and in total, 66 set operations were done for all nets. Generalized Linear Mixed Models (GLMM) was used to compare fish sizes caught with experimental and commercial deep water cast nets. Results showed that more than 70 percent of the individuals caught in cast nets with 16 mm, 20 mm and 24 mm size were below the minimum landing size of whiting (13 cm). Among tested nets, only cast net with 32 mm size caught significantly less individuals under the minimum landing size. Finally, the results obtained from this study are discussed in terms of sustainable fisheries of whiting in the Black Sea.

Reproduction and Seasonal Growth Estimates of the Black Goby, Gobius niger (Osteichthyes: Perciformes: Gobiidae) in the Southeastern Black Sea Region of Turkey

Seasonal growth pattern and reproductive biology of the black goby, Gobius niger, were studied in southern Black Sea between December 2012 and November 2013. The seasonal von Bertalanffy growth parameters, computed from ELEFAN, were estimated as L∞ = 11.90 cm TL, K = 0.701 year-1, C = 0.633, and WP = 0.492 for the Hoenig seasonal model and as L∞ = 12.14 cm TL, K = 0.680 year-1 for non-seasonal von Bertalanffy model. The size at sexual maturity (TL50) was estimated as 8.9 cm TL. The GSI ranged 0.60 in December and 8.57 in April (mean 3.82±0.818) for females and between 0.61 in October 2013 and 2.90 in May 2013 (mean 1.70±0.260) for males. The seasonal growth was pronounced probably due to reproduction activity which extended investment of energy in reproduction causing slower growth. The GSI development was related to photoperiod and the monthly variations of GSI values indicating that the intensive spawning occurred between April and August. During spawning time, the mean GSI value of females (6.04±1.177) was 2.9 times higher than the mean GSI values of males (2.08±0.423) (P < 0.05). The results of this study were offered as biological input parameters regarded as a reference for the conservation and management of the Black Sea stocks of the black goby.

Comparison of Ni enrichment and background concentrations in the Southeastern Black Sea sediments

Surface sediment samples were collected at 104 stations in 34 different locations in seasonal periods in 2013–2014 on the southeastern coasts of the Black Sea. Nickel concentrations were measured with ICP-MS after microwave digestion and were higher in two seperate region than that of others. Relatively high Ni concentrations were found in Bafra (148 ± 18 mg/kg), Dereköy (147 ± 24 mg/kg), Canik (95 ± 35 mg/kg), Çaltıburnu (129 ± 13 mg/kg), Çarşamba (127 ± 4 mg/kg), Terme/Ünye (94 ± 28 mg/kg), Akçaabat (95 ± 13 mg/kg), Çarşıbaşı (77 ± 14 mg/kg), Vakfıkebir (64 ± 5 mg/kg) and Görele (53 ± 15 mg/kg). Nickel concentrations were higher than Effects Range-Medium (ERM) limits in the western and middle part of the region. Ni enrichment levels in sediments were calculated from both core data and earth crust values as a background. It was determined that the enrichment factors found by using earth crust values produced quite misleading results due to the geological variation of the region. It is also concluded that Ni concentrations in marine sediments of the southeastern coasts of the Black Sea are related to terrestrial geological structure.

Feeding Habit and Length-Weight Relationship, Sciaena umbra Linnaeus, 1758 from Southeastern Black Sea

There are many studies on the growth, reproduction, and diet of Sciaena umbra Linnaeus, 1758 in the Mediterranean Sea, while general information on the species is scarce with only a few limited regions from along the Turkish coasts of the Mediterranean Sea, the Aegean Sea, Sea of Marmara and the Black Sea. A total of 217 individuals, 98 males, and 119 females were obtained between March 2018 and February 2019 from the Southeastern Black Sea (Ordu province). Length of the individuals ranged from 11.70-48.20 cm, and weight ranged from 16.43-1934.48 g. According to IRI % analysis, the primary prey group is crustaceans for all individuals and each sex. The secondary prey group was teleost and the third was mollusks. This study extends the current knowledge of length and weight relationships and dietary habits of near threatened brown meagre for its long-needed sustainable management, especially in the Black Sea.

Are Cloth Tarpaulin Mounted Nets Effective for Discard Reduction in Trammel Nets?

Discarding is a significant problem due to net damage and labour loss in trammel net fisheries. In this study, the effects of 15, 25, and 35 cm high cloth tarpaulin rigged between the lead line and the net were investigated in reducing the discard amount of trammel nets for red mullet (Mullus barbatus) in the south-eastern Black Sea. During the study, twenty fishing trips were carried out on-board a commercial vessel between May 11 and June 20, 2018. Results showed that there were no significant differences in the amount of discards between the commercial and experimental nets (P>0.05) However, cloth tarpaulin mounted nets (CTMN) were found to be significantly successful to reduce the amount of shore crab (Liocarcinus depurator) and the veined rapa whelk (Rapana venosa) (P<0.05). Although it is insignificant, a decline of capture was also observed in the amount of target species in CTMN compared to the commercial net (CN). Finally, the advantages and concerns of this gear modification, and potential reasons for the reduction of target and discard species are discussed.

Seasonal and spatial distribution of Noctilucoid dinoflagellates (Noctilucales, Dinophyceae) in the Southeastern Black Sea

Seasonal and spatial distribution of Noctilucoid dinoflagellates collected from three stations (river mouth, coastal and offshore waters) were investigated between May 2015 and April 2016 in the SE Black Sea. Noctilucoid dinoflagellates were represented with four species, Noctiluca scintillans (Macartney) Kofoid & Swezy, 1921, Scaphodinium mirabile Margalef, 1963, Spatulodinium pseudonoctiluca (Pouchet) J.Cachon & M.Cachon, 1968 and Pronoctiluca pelagica Fabre-Domergue 1889. The abundance of Noctilucoids ranged between 0 and 575 cells l−1 in the first 100 m of the water column during study. Noctilucoid dinoflagellates comprised 0.0–48.5% of total dinoflagellate abundance in the study area with the highest percentages occurring in May 2016. Noctiluca scintillans was the most abundant species being associated with 45.6% of total Noctilucoids followed by P. pelagica (30.8%), S. mirabile (13.3%) and S. pseudonoctiluca (5.9%). There were no significant differences on Noctilucoid distribution between stations (p>0.05, one-way ANOVA), however significant differences were found between sampling dates with the highest in May (p<0.05, t-test). S. mirabile and S. pseudonoctiluca were reported for the first time from the Southeastern Black Sea.

New insights into source and dispersal of Mediterranean S1 tephra, an early Holocene marker horizon erupted at Mt. Erciyes (Turkey)

Deposition of early Holocene Eastern Mediterranean S1 tephra and a Black Sea cryptotephra coincides with cultural transitions in the Fertile Crescent termed the Neolithic Revolution as well as sapropel formation during climate variability of the African humid period, classifying them as paramount regional marker horizons for archaeology as well as paleoclimatology. Their correlations with specific eruptions of the Mt. Erciyes stratovolcanic complex (Central Anatolia) remained inconclusive though. Here, we use zircon double-dating by (U–Th)/He and U–Th disequilibrium methods, major and trace element tephra glass geochemistry, and probabilistic modeling of tephra dispersal in an attempt to characterize all major late Quaternary proximal tephras of Mt. Erciyes, and to correlate them with distal deposits. Furthermore, we discuss contrasting proximal and distal tephra dispersal.Three nearly-coeval rhyolitic satellite domes (Dikkartın, Perikartın, and Karagüllü) erupted at Mt. Erciyes in the early Holocene, and their dome extrusions were all preceded by explosive phases producing pyroclastic material that formed tephra fall and pyroclastic flow deposits. The new eruption age of 9.03 ± 0.55 ka (1σ uncertainty here and elsewhere) for proximal Dikkartın pumice is consistent with 14C-based S1 tephra chronologies in distal locations averaging 8.92 ± 0.03 cal ka BP. Perikartın pyroclastic flow deposits predate S1 tephra by ca. 0.8 ka according to a pair of published 14C ages, and stratigraphically overlie Karagüllü fall-out, here dated to 8.2 ± 1.8 ka. Previously undated proximal tephras of Mt. Erciyes erupted in the Late (85.2 ± 4.9 ka) and Middle Pleistocene (154.5 ± 5.3 ka). S1 tephra glass is chemically similar to that of Dikkartın fall-out, but also indistinguishable from that of Perikartın fall-out. Karagüllü pumice is characterized by a distinct glass chemical composition, which correlates with that of unnamed cryptotephra reported for the southeastern Black Sea instead, where these results call for a re-evaluation of existing age models.Maximum lithic clast size isopleths for proximal Dikkartın fall-out indicate eastward dispersal of a 20 ± 5 km high eruption plume by stratospheric winds, in agreement with results of probabilistic tephra dispersal modeling. This azimuth contrasts with the known distribution of S1 tephra at distal locations that are all south of Mt. Erciyes. Significant tephra occurrences at up to 1300 km distance and orthogonal to prevalent stratospheric wind directions either result from very atypical wind conditions (probability ≪10 %), or are caused by tephra transport by prevailing low altitude winds. Two scenarios are proposed for low altitude transport: eolian reworking of primary fall-out (more likely from the more widespread Dikkartın deposits), or co-ignimbrite ash cloud dispersal (more likely from the Perikartın eruption which predominantly produced pyroclastic flows). Because S1 tephra is chemically indistinguishable from both Dikkartın and Perikartın by major and trace element glass compositions, its exact source and dispersal mechanism remain ambiguous, although existing 14C ages for Perikartın predating those for S1 tephra favor Dikkartın as its source.

Phytoplankton pigment indices and pigment-based phytoplankton size classes along the south-eastern Black Sea

Phytoplankton size classes (PSCs) estimated by using high-performance liquid chromatography (HPLC) pigment data and pigment indices in the south-eastern Black Sea were used to characterise seasonal phytoplankton structure from November 2015 to August 2016. Results revealed significant seasonal variation in phytoplankton size classes hence community composition and pigment indices along the south-eastern Black Sea, varied from 2% to 71%; from 3% to 77%; from 5% and 91% for picophytoplankton, nanophytoplankton and microphytoplankton, respectively. Phytoplankton community composition was dominated by microphytoplankton with a high content of photosynthetic carotenoids. In-situ Chl-a concentrations changed during the study period, the highest concentration was detected in autumn (2.60 μg.l−1) and spring (2.48 μg.l−1). Pigment indices indicated that microphytoplankton carrying majority of photosynthetic carotenoids (PSCTP) dominated the community along the south-eastern Black Sea. PSCTP positively correlated with MicroDP, indicated that microphytoplankton seasonally optimise their light-harvesting capability along the south-eastern Black Sea. However, concomitant increase in PPCTPwith PicoDP and dominancy of PPCTP in summer indicated enhancing photoprotective carotenoid content during warm and nutrient depleted periods along the study area. Canonical correspondence analysis (CCA) explained general pattern of PSCs along the study area are controlled seasonally by physicochemical drivers (i.e. nutrient dynamics and pigment content). The differences detected phytoplankton community composition also indicated phytoplankton adaptive strategy to changing environmental factors.

The Norwegian‐Greenland Sea, the Laschamps, and the Mono Lake Excursions Recorded in a Black Sea Sedimentary Sequence Spanning From 68.9 to 14.5 ka

AbstractA full‐vector paleomagnetic record, comprising directional data and relative paleointensity (rPI), was derived from 16 sediment cores recovered from the southeastern Black Sea. The obtained data were used to create a stack covering the time window between 68.9 and 14.5 ka. Age models are based on radiocarbon dating and correlations of warming/cooling cycles monitored by high‐resolution X‐ray fluorescence (XRF) elementary ratios and by ice‐rafted debris (IRD) in Black Sea sediments to the sequence of “Dansgaard‐Oeschger” (D‐O) events defined from the Greenland ice core oxygen isotope stratigraphy. The reconstructed prominent lows in paleointensity at about 64.5, 41.2, and 34.5 ka are coeval with the Norwegian‐Greenland Sea, the Laschamps, and the Mono Lake excursions, respectively. For a further analysis, the stacked Black Sea paleomagnetic record was converted into one component being parallel to the direction expected from a geocentric axial dipole (GAD) and two components perpendicular to it (EW, inclined NS), representing definitely only non‐GAD components of the geomagnetic field. Discussions of the field configurations at the Black Sea site are focused on the three excursional events. The Norwegian‐Greenland Sea excursion was dominated by a decaying axial dipole and persisting weak nondipole field, with directional variations still within the range of normal secular variations. The Laschamps excursion comprises two full polarity transitions and a short stable interval of reversed polarity in between. The Mono Lake excursion was mostly dominated by a nondipole field, though with a less pronounced weakening of the axial dipole component.

Weight - Length Relationships (WLRs) of Anchovy, Engraulis encrasicolus with the Evaluation of Overfishing Effects on the Slope (b) in the Black Sea (Turkey)

The present study was conducted to determine the weight-length relationships (WLRs) of Anchovy (Engraulis encrasicolus) caught by purse seine off the Rize and Trabzon provinces coasts of the southeastern Black Sea, Turkey and to compare as a whole the WLRs parameters of E. encrasicolus obtained from different fishing seasons and locality for contributing fisheries management of this Black Sea’ key fish species. The WLRs parameters showed that E. encrasicolus exhibited negative allometric growth characteristics for both sexes (Pauly’t test, P &amp;lt; 0.05). To compare the estimations calculated from the present study with other studies, Log (a) values were plotted against values of slope (b), proved to be consistent with previous studies data. In addition to this, when the WLRs parameters (b) of Anchovy is evaluated historically, it has been determined that the Anchovy exhibited positive allometric growth in the mid-1985, isometric growth from 1990 to 2000 and negative allometric growth after the 2000s. The overexploitation on anchovy stocks has shown itself in fish growth over the years. This study provides new basic information on the LWRs for Anchovy stocks, in support of sustainable fisheries management of this species and especially of the coastal waters in the Black Sea, Turkey.

Güneydoğu Karadeniz’in Fatsa kıyılarında kullanılan dip uzatma ağlarıyla yakalanan avın miktarı üzerine derinlik ve mevsimin etkileri

The study was conducted along the Fatsa coasts of the South-eastern Black Sea, to investigate the effects of depth and season on catch volume of the bottom gillnet fishery. During the study, fishing was carried out using multifilament gillnets with mesh sizes of 32, 34, 36 and 38 mm in each of the four different depth strata (0-14 m, 15-29 m, 30-49 m and ≥50 m) three times per month between March 2013 and February 2014 (except for July and August), with a total of 30 gillnet hauls performed. The results of the study revealed that in all seasons whiting (Merlangius merlangus) was caught most in the 30 m and deeper water layers. However, whiting catch increased with increasing water depth. Most red mullets (Mullus barbatus) were caught in the 0-14 m depth waters during spring, winter and autumn periods, while its catch was the greatest in the 15-29 m during the summer period. Catch of this species decreased gradually with increasing water depth. Another fish species was pontic shad (Alosa immaculata) which was caught least in the shallow waters. However, during all seasons its catch increased gradually with increasing water depth up to the 30-49 m depth strata. Nevertheless, it was determined that catch volume for this species decreased in the ≥50 m level again. On the other hand, Mediterranean horse mackerel (Trachurus mediterraneus) was mostly caught in the shallow waters (0-14 m and 15-29 m) during all seasons. Especially in the ≥50 m waters, no Mediterranean horse mackerel was sampled during the study. This study presents that amounts of catch for the fish species sampled were affected especially by water depth and seasons.

The composition of cultivable bacteria, bacterial pollution, and environmental variables of the coastal areas: an example from the Southeastern Black Sea, Turkey

The composition and metabolic properties of cultivable heterotrophic aerobic bacteria, the levels of indicator bacteria, and physicochemical parameters were investigated in the seawater samples collected from 20 stations in coastal areas of the eastern part of the Black Sea, Turkey, between May 2017 and February 2018. The levels of indicator bacteria were detected above the national limit values during the study period. Thirty-five different bacterium species were identified. Enterobacteriaceae was recorded as the most dominant family (34.2%), and Gammaproteobacteria was recorded as the most dominant class (74.2%). Bacteriological threats on human and ecosystem health were determined in coastal areas of the Southeastern Black Sea. The determination of the high levels of indicator bacteria, the high ratio of fecal coliform/fecal streptococci (FC/FS ratio), and pathogenic bacteria regarding human and ecosystem health showed that these coastal areas under the influences of terrestrial and human-sourced bacteriological pollution. This study has contributed to the increase of knowledge of understanding the protection and rehabilitation ways of the Black Sea coastal regions against land-based pollution sources considering the interdependent structure of all Black Sea countries. Coastal areas are accepted as the most fragile part of the marine environments and our findings showed the potential bacteriological risks in coastal areas of the Southeastern Black Sea as an important example. Serious precautions should be taken for the protection in this area and such coastal ecosystems to prevent hazardous problems.

Heavy metals in sediments of two nearby streams from Southeastern Black Sea coast: Contamination and ecological risk assessment

Heavy metal pollution in the sediments of Çalışlar and Akçaova Streams may expose hazardous risk to environment and public health through food chain in Ordu province of southeastern Black Sea region of Turkey. The enrichment and distributions of the heavy metals in the sediments of these two streams demonstrated a decreasing trend in the mean heavy metal toxic levels in mg kg−1 as follows Fe (8135.27) > Mn (272.56) > Zn (25.68) > Cu (13.03) > Co (5.13) > Pb (3.74) > Ni (3.62) > Cr (3.52) > Cd (0.005) in Çalışlar Stream and Fe (9939.12) > Mn (286.97) > Zn (24.24) > Cu (19.31) > Ni (10.95) > Co (6.2) > Cr (4.90) > Pb (3.97) > Cd (0.09) > Ag (0.07) in Akçaova Stream, respectively. The sum of the toxic units of Fe, Mn, Zn, and Cu in both streams were significantly higher. The assessment of sediment pollution was carried out using multivariate statistical approaches and indices such as enrichment factor (EF), contamination factor (CF), geoaccumulation index (Igeo), and potential ecological risk factor (Eri). The results of the cluster analysis in both streams showed that Co, Pb, and Cr were mainly associated with natural sources. EF values indicated that the average concentration of all metals from both streams were lower than potential effect levels with the exception of Cu, and Ag in Akçaova Stream. Relatively low levels of pollution indicators in Çalışlar Stream pointed out no environmental contamination and suggested that metal contamination sourced most likely from the naturally present minerals in the area. Akçaova Stream sediments were moderately contaminated with Cu (EF > 2), and significantly contaminated with Ag (EF = 5 − 20) according to the average EF values attributable to anthropogenic activities.

The metal behind the myths: iron metallurgy in the south-eastern Black Sea region

Abstract