The growth response of a diatom Cylindrotheca closterium strain (DEB132303) isolated from the Golden Horn Estuary (Sea of Marmara) was investigated under different environmental conditions. C. closterium cells were grown in a silica-enriched K-medium under various temperatures (11, 18, 25 and 32°C), salinities (6, 12, 18, 24, 30 and 36 psu) and irradiances (10, 20, 50 and 65 μmol photons m⁻² s⁻¹). By the end of the acclimatization period, no viable C. closterium cells were present at temperatures of 4°C and 32°C and salinities of 6 and 36 psu, which marked the upper and lower boundaries of its environmental tolerance. The maximum specific growth rates (µmax) were 1.45 d⁻¹ at temperature of 18°C (18 psu, 50 μmol photons m⁻² s⁻¹), 1.08 d⁻¹ at salinity of 24 psu ( 18°C, 50 μmol photons m⁻² s⁻¹) and 1.80 d⁻¹ at irradiance of 65 μmol photons m⁻² s⁻¹ (18°C, 18 psu), in temperature, salinity and light experiments, respectively. The maximum cell density (Dmax) was 5×10⁵ cells mL⁻¹ at temperature of 25°C, salinity of 18 psu and irradiance of 50 μmol photons m⁻² s⁻¹. Growth rate varied significantly among different temperature, salinity and irradiance treatments (ANOVA, p<0.001) and there was a positive correlation between growth rate and irradiance (r= 0.98, p<0.01). These results demonstrate that these environmental parameters affect significantly the growth of this C. closterium strain.

This research aims to assess the influence of varying concentrations of caffeine (CA), one of the pharmaceutically active compounds, and its metabolites (i.e., paraxanthine (PX), theophylline (TP), and theobromine (TB)) on the growth of common marine phytoplankton ( Isochrysis galbana and Thalassiosira pseudonana) under controlled laboratory conditions. Additionally, the study estimates the daily discharge of CA into marine ecosystems utilizing a developed model. The most effective metabolite inhibiting the proliferation of I. galbana was determined as TP (68.5%) at a concentration of 500 mg/L, while it was CA (65.8%) at the same concentration for T. pseudonana. . After exposure to CA, the IC50 values for I. galbana and T. pseudonana were calculated as 107.3 mg/L and 136.8 mg/L, respectively after 96 hours. Furthermore, the lowest IC50 50 concentration was 7.4 mg/L in TP treatment in I. galbana. . Based on a computational model developed in the paper, in a province with about 2 million inhabitants, where all wastewater is treated in wastewater treatment plants (WWTP), the quantity of CA discharged into the sea was computed as 8.11 kg/day. The CA amounts reaching the sea were potentially increased in regions devoid of wastewater treatment infrastructure. Consequently, WWTPs should undergo expansion and enhancement of their capacity, including advanced treatment for chemical removal for sustainable marine life. Additionally, further studies are needed to elucidate the mechanisms underlying the inhibition effects of CA on phytoplankton.

Although the effect of salinity on phytoplankton community structure has been studied in many coastal lagoons at different times, it has not been studied simultaneously in different lagoons that are not on the same delta but are geographically close to each other. In the present study, the effect of temporal and spatial changes in salinity on the phytoplankton biovolume, species richness, diversity, and species composition was investigated seasonally in 2020 and 2021 in 6 coastal lagoons of Marmara Basin (Türkiye). In more saline lagoons, phytoplankton biovolume, species richness, diversity, and the total number of species were lower. In lagoons which salinity values were approximate, the species composition was similar. Although the salinity in the lagoons did not show significant change seasonally, biovolume values were lower in Mert lagoon in the fall of 2020 when the salinity values were higher compared to the spring of 2021. Moreover, the considerable decrease in salinity shifted the dominant species structure from high salinity optima species to low salinity optima species in this lagoon. Other effective parameters in the seasonal distribution of dominant species were detected as temperature, dissolved oxygen, alkalinity, and nitrate nitrogen.

This study aims to reveal the freshwater mollusc assemblages from 6 sites sampled along Gonen cayi, a stream which flows into the southern Marmara Sea in north-western Turkiye. The stream was sampled using the multi-habitat sampling method with a hand net. Ten species of freshwater molluscs, most of which are widely distributed in Turkiye, were found in the study area. Among these taxa was an unidentified species of Bithynia, which was only present at 1 site. Its shell and anatomy were compared with other Bithynia species from Turkiye and neighbouring countries and found to differ, which revealed that it is a new species. The discovery of the new species increases the diversity of Bithynia in northern Turkiye to 4 species, and to 11 species for Turkiye. This paper highlights the diversity and endemism of freshwater molluscs in Turkiye and emphasizes the need for further research on the distribution of bithyniid species in the country.

The widespread mucilage (sea-snot) formation in the Sea of Marmara in 2021 and 2022 has again shown the importance of environmental protection, monitoring of environmental disasters, and the use of remote sensing for this purpose. The processing of multispectral and hyperspectral data acquired by Earth observation satellites provides important alternatives to costly field and laboratory studies, for the detection and analysis of environmental disasters such as mucilage. In this work, mucilage is detected and analyzed from data acquired by GOKTURK-I, which is one of Turkiye's Earth observation satellites, using an unmixing approach that takes spectral variability into consideration. The proposed approach enables the detection and spectral and spatial analysis of mucilage with high accuracy, without requiring ground truth labels or precisely set thresholds.

The sources and depositional history of 16 polycyclic aromatic hydrocarbons (PAHs) and 18 polychlorinated biphenyl (PCBs) congeners in the Golden Horn estuary (İstanbul) were investigated using a dated sediment core for the period between 1880 and 2012. The concentrations of PAHs and PCBs were calculated for every 4 cm slices of the sediment core and ranged from 1203.5 to 3441.4 ng/g and 5.4 to 41.4 ng/g, respectively. The diagnostic ratios indicated that the maximum PAH values correspondence to combustion after a crude oil-carrying Romanian tanker (Independenta) accident in the İstanbul Strait in 1979. The historical deposition of PAHs and PCBs in the Golden Horn was influenced by municipal effluent and heavy industrial dischargers approximately 50 years. When the Silahtarağa thermal power plant (TPP) was operating, PCB pollution rose; however, after a thorough rehabilitation effort and the outlawing of PCB use in the 1990s, pollution levels significantly tended to decrease.

In this study, biosorption processes performed with and without ultrasound-assisted were presented for the first time comparatively. For this purpose, the potential for use of Ulva lactuca Linnaeus 1753 (U. lactuca) which is a macroalgae, as an alternative biosorbent was investigated for Hg(II) removal from aqueous solutions. Both conventional univariate and multivariate methods were evaluated to optimise biosorption processes. Biosorption equilibrium time was determined as 60 min for without ultrasound-assisted method, while it was only 3 min for ultrasound-assisted method. Biosorption processes were optimised by Central Composite Design (CCD) and successfully described by quadratic polynomial models as a function both of R (%) and qe (mg/g). In optimum conditions (Co = 125 mg/L, m = 30 mg, pH = 4.0 for ultrasound-assisted method and pH = 2.0 for without ultrasound-assisted method), removal efficiencies were achieved experimentally as 95.8% +/- 0.2 and 96.1% +/- 0.7 (N = 2), respectively. Models with high regression coefficients (R-2(adj) > 95%) obtained from Response Surface Methodology (RSM) were found to be applicable to the estimation of biosorption data. Biosorption equilibrium data was defined by Langmuir model. Langmuir's maximum sorption capacity was increased from 125.6 to 232.0 mg/g when ultrasound-assisted method was applied. According to the results of kinetics evaluation, both biosorption processes were thermodynamically possible, endothermic (Delta Ho>0) and spontaneous reactions (Delta Go<0) controlled by chemisorption based on the pseudo-second-order kinetic models. Results showed that ultrasound-assistance to the biosorption process contributed positively to increasing the rate of reaction and allowing sorption to be completed in a shorter time by facilitating sorption mass transfer.

Sediment, notothenioid fish, and moss samples were collected from the vicinity of Galindez Island, Antarctic Peninsula during the austral autumn of 2016 and 2017. Pesticide, Polycyclic Aromatic Hydrocarbon (PAH), and dioxin-like Polychlorinated Biphenyl (dl-PCB) concentrations were measured using High-Resolution Gas and Liquid Chromatography. Pollutant concentrations were below detection limits in sediment and moss samples. However, pesticides, PAH, and dl-PCB congeners were detected in the muscle tissue of fishes. Pesticide concentrations varied between 0.46 and 12.2 ng/g-dw, and Mecarbam was the dominant compound. Kresoxim-methyl, Mecarbam, Procymidone, Pyridaben, and Quinoxyfen were reported in the muscle tissue of the fishes, for the first time from the Antarctic. PCB-118, PCB-105, and PCB-156 were dominant dl-PCBs. The ∑12-dl-PCB concentration was 160,929 pg/g-dw, and WHO-TEQ-total dl-PCB was 8.30 pg/g-dw in Trematomus bernachii, over the consumable limit in fishes according to the European Commission. The PCB-126 concentration was 36 pg/g-dw in the muscle tissue of fish, the first reported from the Antarctic. Phenanthrene was the dominant PAH congener. The ∑16-PAH concentration was 22.5 ng/g-dw. PAH sources were local and petrogenic in the fishes, likely after long-term bioaccumulation. The flow rate is rather low around Galindez Island; accordingly, contaminant removal takes time and may demonstrate long-lasting effects including bioaccumulation in the marine food web.

The present study aimed to develop a multimetric index as a biological indication method of water quality using benthic macroinvertebrates for Turkey. A total of 207 operational taxa units were identified from 26 sampling sites through the employment of the multi-habitat method. Water was simultaneously sampled for both in-situ measurements and laboratory analysis in order to obtain the data on water chemistry. Ineligible metrics were excluded from the calculation process together with box-whisker plots and Kruskal–Wallis test (p < 0.05), considering the degree of overlap in the quartile limits (1°-3°). Among ten candidate metrics, four were considered suitable to form a multimetric index through Spearman correlation analysis. The core metrics were standardized with the 3rd quartile to obtain the index value. The index responded to a set of environmental variables, and split the ecological conditions into four categories as high, moderate, poor, and bad for the study area. Our results indicate that the multimetric index of the Sakarya River (MMIS) is an effective biological monitoring tool employing macroinvertebrates for biological monitoring in Turkey.

Bu çalışma Dilderesi, Yalakdere ve Kirazdere akarsularının taban makroomurgasız faunasını belirlemek amacıyla Şubat 2019 – Kasım 2019 tarihleri arasında gerçekleştirilmiştir. Örneklemeler, her akarsuyun üç farklı bölgesinden seçilmiş, toplam dokuz örnekleme istasyonunda mevsimsel olarak yapılmıştır. Makroomurgasızların örneklenmesinde çoklu habitat yöntemi, Kuadrat ve Van Veen Grab kullanılarak uygulanmıştır. Laboratuvarda gruplarına ayrılan organizmalar, uygun teşhis anahtarları kullanılarak tayin edilmiştir. Çalışma sonuçlarına göre, Kirazdere akarsuyunda 45 familyaya ait 114 takson, Yalakdere akarsuyunda 33 familyaya ait 98 takson ve Dilderesi akarsuyunda 32 familyaya ait 89 takson olmak üzere toplamda çalışma boyunca 179 takson belirlenmiştir. Tespit edilen taban makroomurgasızlardan Caenis sp. ve Paratrichocladius rufiventris’in en yaygın taksonlar olduğu belirlenmiştir. Akarsuların mansaba yakın istasyonlarında sadece Oligochaeta, Chironomidae ve Gastropoda’ya ait taksonlar tespit edilirken, akarsuların kaynağa yakın istasyonlarında özellikle Ephemeroptera, Plecoptera, Trichoptera gruplarına ait taksonlar tespit edilmiştir. Bu çalışma Dilderesi ve Kirazdere akarsularında taban makroomurgasız faunasının belirlenmesine yönelik ilk çalışmadır. Bunun yanında, 90 takson Yalakdere akarsuyu için yeni kayıttır.

In this study, the Macrophyte Biological Index for Rivers (IBMR) method and physicochemical measurements were used to assess the trophic status of the Sakarya River Basin in Turkey. The most abundant macrophytes were Phragmites australis, Thypa latifolia, Juncus sp., and Paspalum distichum. The IBMR values varied between 6.00 and 13.00 in spring, and between 6.714 and 14.40 in the fall season. The sampling stations, which are under the influence of agricultural runoffs, domestic effluents, and industrial discharges, had hypoxia accompanied by eutrophic and/or hypertrophic conditions at least in one season. The individual trophy levels of the sampling sites in the basin have been assessed as mesotrophic to eutrophic. However, considering the average IBMR value of all stations, the general trophy level of the basin was close to eutrophic. The results indicate that the physicochemical parameters are affected by various effluents discharged to the basin as observed during field studies, and the obtained data would be useful to apply conservation measures.

The paper presents a mass balance modeling study on the polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) pollution around the Izmit Bay region, the most industrialized province of Turkey, based on the evaluation of PCDD/Fs input to the bay and measured concentrations in the surface sediments. The pollution map showed that PCDD/F levels in the central section are much higher than those in the eastern and western basins. The model showed that OCDD levels could be explained mainly by the effect of atmospheric deposition processes whereas other dominant congeners i.e., Octachlorodibenzofuran (OCDF) and 1,2,3,4,6,7,8-Heptachlorodibenzofuran (1,2,3,4,6,7,8-HpCDF), observed in the surface sediment, should have another unknown sources. Assessment of the congener profiles of the industrial discharges in the recent studies showed that OCDF was related to the production of vinyl chloride monomer in the past, 1,2,3,4,6,7,8-HpCDF was attributed to unknown use of the chlorophenol-based fungicide. On the other hand, atmospheric OCDD could be explained by the effect of combustion-related PCDD/F emissions, and the use of pentachlorophenol (PCP) pesticide. In conclusion, the mass balance model results suggested that the industrial discharges in the past could be a significant contributor to the PCDD/F pollution in the sediments.

To test the effects of lake morphometry (lake size and depth) on water quality parameters which affect the phytoplankton functional groups (FG) distribution, phytoplankton and some environmental parameters were sampled in November 2017 and May 2018 at the two or three monitoring stations in nine Lakes of Sakarya River Basin (Turkey). Lake size and depth affected phytoplankton FG distribution in both large-sized and small-sized lakes by affecting light availability which was mainly driven by the mixing events during the studied period. Although PO4-P and alkalinity were the other main environmental constraints influencing phytoplankton distribution, they were not directly affected by lake morphometry. Codon Lo was mainly found in small-sized and shallow lakes, whereas coda B, C, D, J, R, and T, which do not have active buoyancy regulation and adapt to high Zmix/Zeu conditions, occurred with high relative biovolwne in large-sized water bodies.

The Sakarya River basin is one of the largest basins in Turkey, and encompasses the Kocaeli, Düzce, Sakarya, Bursa, Bilecik, Bolu, Kütahya, Eskişehir, Ankara, Afyon, and Konya provinces. In this study, the water quality status of the basin was investigated using 18 diatom indices, calculated in Omnidia software. For this purpose, a total of 46 stations were surveyed in the rivers and streams of the basin in May 2018. As a result, 41 of 195 diatom taxa were found to be the most frequent (>10% share in assemblage). According to Detrented Correspondence Analysis (DCA), three subgroups were described as the spring section, Ankara and Polatlı section, and lowland section. The river basin quality was evaluated as moderate or lower quality status, while only a few sites had good status. The diatom index scores showed that the Descy’s Index (DES), Pampean Diatom Index (IDP), Artois-Picardie Diatom Index (IDAP), and Specific Pollution Sensitivity Index (IPS) appear best suited to water quality assessment in this area, showing the largest number of significantly important correlation with environmental variables.

A series of red tides were observed during 2015 in the Izmit Bay (the Marmara Sea) which is located in the most industrialized and populated region of Turkey. Six samplings were carried out in this area following the red tides. Nitrite-N, nitrate-N, ammonia, silica and orthophosphate concentrations were analyzed spectrophotometrically. Physicochemical conditions were measured by CTD probe. Plankton quantification was performed using counting chambers under microscopes. Prorocentrum micans was the most abundant species, except on May 14, 2015, when Noctiluca scintillans was dominant. The abundance of P. micans reached average 18×10 6 ind./L on May 3, 2015 in the Karamürsel station, simultaneously with elevated levels of NH 3 and o-PO 4 3– . The sample was also abundant in dead amphipods ((72±12) ind./L) that had been covered by mucilage aggregates produced by P. micans . The highest biomass (calculated by carbon) was recorded as (268±26.0) mg/L on May 14 in the Hereke station. Beside the anthropogenic wastewater discharges, unknown sources and resuspensions caused increases in nutrient levels. After long term northeaster gusts (35 km/h for 5 d) an upwelling occurred on November 6, 2015 after wind-induced sediment resuspension. Although nutrient discharges remarkably decreased over 30 years through established wastewater treatment plants, harmful phytoplankton blooms still occur. Comparing the present results with other studies in nearby Mediterranean seas reveals that the most intense harmful dinoflagellate bloom in recent years occurred in the Izmit Bay. Therefore, additional protection measures necessary for a cleaner Izmit Bay. These incidents also demonstrate that contaminants, accumulated in sediment, may have long-lasting effects on enclosed marine ecosystems.

Western Antarctic Peninsula is one of the fastest warming areas on Earth and coastal areas of the region are foremost affected. Here we present the state of coastal plankton assemblages of the Galindez Island and Neumayer Channel, Western Antarctic Peninsula in austral autumn (April 2016). Surface water temperatures were ranged between -0.12 degrees C and -0.97 degrees C and average chlorophyll-a concentrations were 0.65 mu g/l. A total of 50 phytoplankton and 24 zooplankton taxa (15 copepods and 9 meroplanktonic species) were identified during the sampling period. Diatom species (78%) predominated phytoplankton and the highest abundance was 820 cells l(-1), while the highest number of phytoplankton species was 42. Zooplankton was prevailed by the dominance of copepods, except contribution of meroplankton at the Neumayer channel. Highest zooplankton abundance was 101 ind.m(-3). The sampling season was the transition period from the productive spring-summer to dormant winter conditions, which explains the low abundances registered, however, on contrary to low cell abundances, diversity was high within plankton.

AbstractThe macrophyte plant distribution in some aquatic habitats and their availability for monitoring the PAH contamination were investigated in Kocaeli Province of Turkey. Alisma plantago-aquatica L. was collected to evaluate polyaromatic hydrocarbon (PAH) contamination in four aquatic habitats located nearby or distant to the industrial facilities and populated city center. Concentrations of eight PAH congeners were measured in A. plantagoaquatica leaves using gas chromatography. PAH sources were estimated using the following ratios, Fluoranthene / (Fluoranthene + Pyrene), Benzo(a)anthracene / (Benzo(a) anthracene + Chrysene) and Anthracene / (Anthracene + Phenanthrene) and were found to be pyrogenic-sourced in all stations. Since the ratios of congeners indicate the pyrogenic contamination, atmospheric deposition can be considered as the main pathway for PAH transportation. The highest ΣPAH concentration (798 μg kg

During the cetacean surveys of the first Turkish-Ukrainian Antarctic Research Expedition conducted on 5-8 April 2016 in Lemaire Channel, Penola Strait, Flanders Bay, southern Gerlache Strait, and southern Neumayer Channel in the Western Antarctic Peninsula, 74 humpback whales (Megaptera novaeangliae) in 24 sightings and 11 Antarctic minke whales (Balaenoptera bonaerensis) in 6 sightings were recorded. The overall encounter rate (number of sightings/survey effort in nautical miles) was 0.333 (0.266 for humpback whale, 0.066 for Antarctic minke whale). According to the sighting distribution, the Lemaire Channel and Penola Strait are important migration and feeding habitats for whales. Five humpback whales were photo-identified individually by natural features on their flukes; one of them had a match in the Antarctic Humpback Whale Catalogue. The matched individual was first recorded on 30 August 2007 at Salinas, Ecuador.