Heavy Metal and Trace Element Levels in Hair Samples from Fishermen in Turkey: The Fish/Ermen Heavy Metal Study (FHMS).

Toxic chemicals from polluted seas can enter the human body through seafood consumption and cause health problems. The aim of this study was to evaluate the levels of selected heavy metals and trace elements among fishermen who frequently consumed seafood and controls who consumed seafood less frequently in four provinces on the shores of the Sea of Marmara, which is heavily polluted by industrial activities. Fourteen elements (antimony, arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, selenium, strontium, vanadium, and zinc) were analyzed in hair samples using the inductively coupled plasma-mass spectrometer method. Levels of arsenic (0.147 ± 0.067 µg/g vs. 0.129 ± 0.070 µg/g, p = 0.025), chromium (0.327 ± 0.096 µg/g vs. 0.269 ± 0.116 µg/g, p < 0.01), nickel (0.469 ± 0.339 µg/g vs. 0.403 ± 0.368 µg/g, p = 0.015), strontium (1.987 ± 1.241 µg/g vs. 1.468 ± 1.190 µg/g, p < 0.01), and zinc (103.3 ± 43.1 µg/g vs. 92.7 ± 37.4 µg/g, p = 0.047) were higher in the fisherman group than in the control group. No difference was found between the groups in terms of other elements. The findings suggest that heavy metal-trace element contamination in the Sea of Marmara may increase the exposure levels of individuals to some chemicals through seafood consumption.

Spatio-temporal distribution of microplastic pollution in surface sediments along the coastal areas of Istanbul, Turkey.

Microplastics (MPs) have become prevalent in various environmental compartments, including air, water, and soil, attracting attention as significant pollutant parameters. This study investigated the prevalence of MP pollution in surface sediments along Istanbul's Marmara Sea, encompassing the megacity and the Bosphorus. A comprehensive sampling approach was employed, covering 43 stations across four seasons and depths ranging from 5 to 70 m. The objective was to assess the impact of terrestrial, social, and industrial activities on MPs. The average concentrations varied per season, with fall, winter, spring, and summer values recorded as 2000 ± 4100, 1600 ± 3900, 4300 ± 12,000, and 9500 ± 20,300 particles/kg-DW. The study identified river stations in the Golden Horn and sea discharge locations as hotspots for high concentrations. Notably, the dominant shape shifted from fibers in fall, winter, and spring to fragments during summer, coinciding with mucilage occurrences. The study identified 11 different polymers, with polyethylene (44 %) and polypropylene (31 %) being the most common.

Does environmental DNA reflect the actual phytoplankton diversity in the aquatic environment? Case study of marine mucilage in the Sea of Marmara.

The present study was designed to assess the effectiveness of the eDNA metabarcoding approach to determine the phytoplankton composition in the marine environment with a special focus on mucilage episodes in the Sea of Marmara. For this purpose, the samples were collected from 5 different sites located in the Sea of Marmara and the northern Aegean Sea during the mucilage episode in June 2021. The phytoplankton diversity was analyzed morphologically and by 18S rRNA gene amplicon sequencing, and the dataset of both methods was compared, accordingly. The results showed significant differences between methods in terms of composition and the abundance of the phytoplankton groups. While Miozoa was the most abundant group by metabarcoding, light microscopy (LM) indicated a dominance of Bacillariophyta. Katablepharidophyta was found at lower abundances by the metabarcoding (representing < 1% of the community); the members of this phylum were not observed by a microscope. At the lower taxonomic levels, Chaetoceros was the only genus detected in all samples by both methods. Additionally, while mucilage-forming Gonyaulax fragilis, Cylindrotheca closterium, and Thalassiosira rotula were detected to species-level by LM, metabarcoding was able to determine these organisms at the genus level. On the other hand, the genus Arcocellulus was found in all metabarcoding datasets and not detected by microscopy. The results indicated that metabarcoding can detect a greater number of genera and reveal taxa that were overlooked by light microscopy but to develop a complete picture of phytoplankton diversity in the sample, microscopical observations still are in need.

Accumulation of organochlorine pesticide (OCP) residues in surface water and sediment from the Iznik Lake in Turkey.

This study was carried out to evaluate organochlorinated pesticide (OCPs) concentrations in the water column and sediments of Iznik Lake. Water samples and sediment were collected in different regions (six sampling sites) of the lake between January and December 2019 and tested for OCPs by gas chromatography-mass spectrometry (GC-MS). The results revealed that OCP residues throughout the sites varied depending on the anthropogenic activities of the region. OCPs detected in surface waters ranged from 0.01 to 60.80 µg/L and sediments from 0.06 to 14.21 ng/g dw. Endrin ketone, endrin aldehyde, endosulfan II, endrin, heptachlor epoxy, beta-BHC, gamma-BHC, ppDDD, and ppDDT concentrations exceeded the maximum residue limits indicated by the World Health Organization (WHO) for surface waters. Of the 18 analyzed OCP components, 17 were detected in sediment samples, and it was noted that they reached the highest concentration in summer. The presence of relatively high OCP levels according to WHO regulations in the waters of Iznik Lake, around which agricultural activities have been increasing rapidly in recent years, is a serious concern, and therefore, appropriate actions should be taken into consideration by the regulatory authorities.

Insights into the bacterial community structure of marine mucilage by metabarcoding.

This prospective study was aimed to explore the bacterial diversity of marine mucilage developed in the Marmara Sea and the North Aegean Sea by metabarcoding. For this purpose, mucilage samples were collected from five different sampling locations, and the bacterial community structure was analyzed by 16S rRNA gene amplicon sequencing. The results highlighted a diverse bacterial community dominated by Proteobacteria and Bacteroidetes species. A negative and significant correlation between pH level and Campylobacterales, Clostridiales, and Vibronales abundances was detected, while a strong positive correlation was determined between total phosphorus (TP) and Campylobacterales. Results revealed that the bacterial community in the mucilage samples was predominated by particle-attached species preferring high-nutrient concentrations. This is the first study evaluating the bacterial diversity in a mucilage outbreak using a metabarcoding approach. Its results may contribute to this growing area of research and provide a database for further studies.

Monitoring of cyanobacterial blooms and assessing polymer-enhanced microfiltration and ultrafiltration for microcystin removal in an Italian drinking water treatment plant.

The water intake of a drinking water treatment plant (DWTP) in Central Italy was monitored over six bloom seasons for cyanotoxin severity, which supplies drinking water from an oligo-mesotrophic lake with microcystin levels up to 10.3 µg/L. The historical data showed that the water temperature did not show extreme/large seasonal variation and it was not correlated either with cyanobacterial growth or microcystin concentration. Among all parameters, the cyanobacteria growth was negatively correlated with humidity and manganese and positively correlated with atmospheric temperature. No significant correlation was found between microcystin concentration and the climatic parameters. Polymer(chitosan)-enhanced microfiltration (PEMF) and ultrafiltration (PEUF) were further tested as an alternative microcystin removal approach from dense cyanobacteria-rich flows. The dominant cyanobacteria in the water intake, Planktothrix rubescens, was isolated and enriched to simulate cyanobacterial blooms in the lake. The PEMF and PEUF were separately applied to enriched P. rubescens culture (PC) (microcystin = 1.236 µg/L) as well as to the sand filter backwash water (SFBW) of the DWTP where microcystin concentration was higher than 12 µg/L. The overall microcystin removal rates from the final effluent of PC (always <0.15 µg/L) were between 90.1-94.7% and 89.5-95.4% using 4 and 20 mg chitosan/L, respectively. Meanwhile, after the PEMF and PEUF of SFBW, the final effluent contained only 0.099 and 0.057 µg microcystin/L with an overall removal >99%. The presented results are the first from the application of chitosan to remove P. rubescens as well as the implementation of PEMF and PEUF on SFBW to remove cyanobacterial cells and associated toxins.

Depth profiles of protein-bound microcystin in Küçükçekmece Lagoon.

Microcystis is the most commonly found toxic cyanobacterial genus around the world and has a negative impact on the ecosystem. As a predominant producer of the potent hepatotoxin microcystin (MC), the genus causes outbreaks in freshwaters worldwide. Standard analytical methods that are used for the detection of microcystin variants can only measure the free form of microcystin in cells. Since microcystin was found as free and protein-bound forms in the cells, a significant proportion of microcystin is underestimated with analytical methods. The aim of the study was to measure protein-bound microcystins and determine the environmental factors that affect the binding of microcystin to proteins. Samples were taken at depths of surface, 1 m, 5 m, 10 m, 15 m, and 18 m in Küçükçekmece Lagoon to analyze depth profiles of two different microcystin forms from June to September 2012 at regular monthly intervals. Our findings suggest that the most important parameter affecting protein-bound microcystin at surface water is high light. Due to favorable environmental conditions such as temperature, light, and physicochemical parameters, the higher microcystin contents, both free and protein-bound MCs, were found in summer periods.

Contrasting the Water Quality and Bacterial Community Patterns in Shallow and Deep Lakes: Manyas vs. Iznik.

The objectives of this study are to monitor the physicochemical properties of two freshwater lakes with different chemical characteristics and trophic status over a year (2019) and assess the bacterial diversity by a high-throughput sequencing method for a certain time. Carlson Trophic Index analysis revealed that, whereas the deep lake, Iznik Lake, (TSImean = 48.9) has mesotrophic characteristics, the shallow lake Manyas Lake (TSImean = 74.2) was found at a hypertrophic status. The most important parameters controlling water qualities in the lakes were temperature, alkalinity, and phosphate levels. Although the bacterial communities were dominated by the same phyla (Cyanobacteria, Bacteroidetes, Actinomicrobia, Proteobacteria, and Verrucomicrobia) in both lakes, the communities differed distinctly at the lower levels. Whereas Sporichthyaceae in Manyas Lake accounted for 10% of the total reads, the major share of the sequences was assigned to Cyanobacteria Family I (8%) in Iznik Lake. The hypertrophic Manyas Lake had a more diverse bacterial community rather than Iznik Lake and contained higher numbers of unique Operational Taxonomic Units.

Heavy Metal Concentrations in Trachurus Mediterraneus and Merlangius Merlangus Captured from Marmara Sea, Turkey and Associated Health Risks.

Rapid industrialization and excessive human population growth may cause deterioration in marine water quality and biodiversity. Heavy metals are one of the most common pollutants in the seas and marine organisms, including demersal and pelagic fish, can accumulate them from the environment. Assessment of the ecological risk of heavy metals from fish has an important role in public health. In this study, some heavy metal (Pb, Cd, As, Cr, Hg, Cu, Zn, and Fe) concentrations were determined in the muscle tissues of two commonly consumed fish species, Trachurus mediterraneus (Mediterranean horse mackerel) and Merlangius merlangus (Whiting), which are the fifth (14,222 tons/year) and sixth (6814 tons/year) highest commercial catches of marine fish species in Turkey, respectively. Heavy metal concentrations of samples collected from four sites (Adalar, Izmit Bay, Yalova, and Tekirdag) in the Marmara Sea were determined using ICP-MS. Fish samples caught at Yalova station were found to have the highest heavy metal concentrations. According to the World Health Organization (WHO), in terms of the mean values, only As, and Cr were higher than permissible limits in T. mediterraneus, while Pb, Cd, As, and Cr were higher in M. merlangus. Arsenic concentrations were higher than maximum limits in both T. mediterraneus and M. merlangus. The estimated weekly intake (EWI) was calculated to assess the potential health impact. The EWI for arsenic, cadmium, lead, and mercury for some sites was above the provisional tolerable weekly intake.

Heavy Metals and Trace Elements in Whole-Blood Samples of the Fishermen in Turkey: The Fish/Ermen Heavy Metal Study (FHMS).

Selected heavy metal-trace element (Ag, As, Ba, Cd, Cu, Hg, Pb, Sb, Se, Sr, and V) levels were determined by the ICP-MS method in whole-blood samples of fishermen and control group who accommodate in four provinces of the Marmara Sea. Mercury (1.267 ± 1.061 µg/L to 0.796 ± 0.853 µg/L) and lead (17.8 ± 9.0 µg/L to 12.0 ± 6.83 µg/L) levels were higher in the fishermen group than that of control group (p < 0.001 for both). There was no difference between the fishermen group and the control group in terms of whole-blood levels of other elements. Total monthly fish consumption was 9340.4 gr in the fishermen group and 326.4 gr in the control group, and the difference between the groups was significant (p < 0.001). There was no difference between the groups in terms of having amalgam dental filling (p > 0.05). The results suggest that consuming high amounts of sea products caught from the Marmara Sea is a source for some heavy metals such as mercury and lead, which poses a public health risk. Unlike the control group, the positive correlation between arsenic, copper, and strontium levels and age in fishermen can also be evaluated as an indicator of chronic exposure.

Seasonal dynamics of freshwater pathogens as measured by microarray at Lake Sapanca, a drinking water source in the north-eastern part of Turkey.

Monitoring drinking water quality is an important public health issue. Two objectives from the 4 years, six nations, EU Project µAqua were to develop hierarchically specific probes to detect and quantify pathogens in drinking water using a PCR-free microarray platform and to design a standardised water sampling program from different sources in Europe to obtain sufficient material for downstream analysis. Our phylochip contains barcodes (probes) that specifically identify freshwater pathogens that are human health risks in a taxonomic hierarchical fashion such that if species is present, the entire taxonomic hierarchy (genus, family, order, phylum, kingdom) leading to it must also be present, which avoids false positives. Molecular tools are more rapid, accurate and reliable than traditional methods, which means faster mitigation strategies with less harm to humans and the community. We present microarray results for the presence of freshwater pathogens from a Turkish lake used drinking water and inferred cyanobacterial cell equivalents from samples concentrated from 40 into 1 L in 45 min using hollow fibre filters. In two companion studies from the same samples, cyanobacterial toxins were analysed using chemical methods and those dates with highest toxin values also had highest cell equivalents as inferred from this microarray study.

Monitoring of freshwater toxins in European environmental waters by using novel multi-detection methods.

Monitoring the quality of freshwater is an important issue for public health. In the context of the European project µAqua, 150 samples were collected from several waters in France, Germany, Ireland, Italy, and Turkey for 2 yr. These samples were analyzed using 2 multitoxin detection methods previously developed: a microsphere-based method coupled to flow-cytometry, and an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. The presence of microcystins, nodularin, domoic acid, cylindrospermopsin, and several analogues of anatoxin-a (ATX-a) was monitored. No traces of cylindrospermopsin or domoic acid were found in any of the environmental samples. Microcystin-LR and microcystin-RR were detected in 2 samples from Turkey and Germany. In the case of ATX-a derivatives, 75% of samples contained mainly H2 -ATX-a and small amounts of H2 -homoanatoxin-a, whereas ATX-a and homoanatoxin-a were found in only 1 sample. These results confirm the presence and wide distribution of dihydro derivatives of ATX-a toxins in European freshwaters. Environ Toxicol Chem 2017;36:645-654. © 2016 SETAC.

Detection of Human Enteric Viruses in Freshwater from European Countries.

The transmission of water-borne pathogens typically occurs by a faecal-oral route, through inhalation of aerosols, or by direct or indirect contact with contaminated water. Previous molecular-based studies have identified viral particles of zoonotic and human nature in surface waters. Contaminated water can lead to human health issues, and the development of rapid methods for the detection of pathogenic microorganisms is a valuable tool for the prevention of their spread. The aims of this work were to determine the presence and identity of representative human pathogenic enteric viruses in water samples from six European countries by quantitative polymerase chain reaction (q-PCR) and to develop two quantitative PCR methods for Adenovirus 41 and Mammalian Orthoreoviruses. A 2-year survey showed that Norovirus, Mammalian Orthoreovirus and Adenoviruses were the most frequently identified enteric viruses in the sampled surface waters. Although it was not possible to establish viability and infectivity of the viruses considered, the detectable presence of pathogenic viruses may represent a potential risk for human health. The methodology developed may aid in rapid detection of these pathogens for monitoring quality of surface waters.

First report of cylindrospermopsin production by two cyanobacteria (Dolichospermum mendotae and Chrysosporum ovalisporum) in Lake Iznik, Turkey.

Cylindrospermopsin (CYN) is a cytotoxic alkaloid produced by cyanobacteria. The distribution of this toxin is expanding around the world and the number of cyanobacteria species producing this toxin is also increasing. CYN was detected for the first time in Turkey during the summer months of 2013. The responsible species were identified as Dolichospermum (Anabaena) mendotae and Chrysosporum (Aphanizomenon) ovalisporum. The D. mendotae increased in May, however, C. ovalisporum formed a prolonged bloom in August. CYN concentrations were measured by LC-MS/MS and ranged from 0.12 µg·mg⁻¹ to 4.92 µg·mg⁻¹ as dry weight, respectively. Both species were the only cyanobacteria actively growing and CYN production was attributed solely to these species. Despite CYN production by C. ovalisporum being a well-known phenomenon, to our knowledge, this is the first report of CYN found in D. mendotae bloom.

Effects of water quality and hydrologic drivers on periphyton colonization on Sparganium erectum in two Turkish lakes with different mixing regimes.

The aim of this paper is to determine and compare the environmental factors controlling vertical colonisation of periphyton on Sparganium erectum in a shallow eutrophic turbid lake, Manyas Lake, and an oligo-mesotrophic deep lake, Sapanca Lake, Turkey during the July 1997--November 1998. To investigate the effect of the environmental factors on periphyton colonization on S. erectum, the stem was cut above the rhizomes and subdivided into three equal sections. Multivariate statistical analyses have been applied to clarify relationships between environmental variables and periphyton colonization on S. erectum. Results indicated that physical disturbance and trophic level of the lakes influenced the colonization of the periphyton. Among the measured parameters, low light intensity, total suspended solids, temperature and water level fluctuation were observed as driving factors in Manyas Lake whereas nutrient deficiency was found as key factor in Sapanca Lake. The zonation of the periphyton, density, composition and dominant/subdominant taxa were significantly different in these lakes. However, Oedogonium sp., Mougeotia sp., Cylindrocapsa sp., Cladophora glomerata (Linn.), Aulacoseira italica (Ehr.) Simonsen, Melosira varians C. Agardh, Navicula tripunctata (O.F. Müller) Bory and Fragilaria ulna (Nitzsch) Lange-Bertalot were found as dominant species at all sections of S. erectum both in Manyas Lake and Sapanca Lake. It can be thought that these species have a broad range of tolerance to several physical, chemical and hydrologic disturbances. This is the first study to introduce how much the water quality and hydrologic drivers have affected vertical colonization of periphyton on S. erectum in two lakes with different mixing regimes.

Microcystin analysis in single filaments of Planktothrix spp. in laboratory cultures and environmental blooms.

Single filaments of Planktothrix spp. were isolated from laboratory cultures of P. agardhii (NIES 595) and P. rubescens (SL 03) and from four freshwater lakes in England and Turkey. Filament lengths were measured and microcystins were extracted by freeze-thawing and boiling. Microcystin analysis of the isolated single filaments was performed by ELISA using antibodies raised against microcystin-LR with a minimum detection limit (MDL) of 11 pg filament(-1). In some cases a high percentage of the filaments from the environmental samples and laboratory cultures were below the MDL of the assay. Based on the filaments with detectable microcystin contents, P. agardhii from Bassenthwaite Lake (England) had the lowest mean microcystin concentration (0.7 fg microm(-3)), and the highest microcystin concentration (2.9 fg microm(-3)) was measured in P. rubescens from Iznik Lake (Turkey). We investigated the relationship for filaments with microcystin contents above MDL and their biovolume. Relationships varied widely although P. agardhii from Bassenthwaite showed a better (positive) relationship between filament biovolume and microcystin content than P. rubescens from environmental samples. Under culture conditions, P. rubescens showed a good relationship between filament biovolume and toxin content.

Occurrence of toxic blue-green algae in the Kucukcekmece lagoon (Istanbul, Turkey).

The concentration of microcystin (MC) in the Kucukcekmece Lagoon, Istanbul, Turkey, and the physicochemical and biological parameters of water quality were investigated from October 2000 to June 2003. Water samples were collected from surface waters at three sites. Most bloom samples were dominated by Microcystis aeruginosa. The major microcystin variants detected by HPLC-PDA were microcystin-YR and microcystin-LR. Microcystin concentration increased dramatically from early summer to early autumn and thereafter tended to decrease. The toxin concentration found in the filtered samples from surface waters varied between 0.06 and 24.2 microg L(-1) microcystin-LR equivalents. Each year extensive fish mortality was recorded between mid-June and early October, coinciding with heavy algal blooms. A comparison of the conditions associated with cyanotoxin episodes in 2000, 2001, and 2002 showed that the microcystin increase was related to temperature, high concentration of dissolved nutrients, high light intensity (PAR). The highest MC concentrations were recorded at temperatures between 24 degrees C and 28.5 degrees C. Field data showed that the highest MC concentration (>3 microg L(-1)) and the highest cyanobacterial biomass (>30 mg L(-1)) corresponded to a total nitrogen:total phosphorus ratio greater than 7:1. The highest concentrations of M. aeruginosa biomass (173 mg L(-1)) and MC (24.2 microg L(-1) MC-LR equiv.) and the highest salinity (8.8%) were measured concurrently in the lagoon. To our knowledge, this is the first evidence of cyanobacterial toxins in the Kucukcekmece Lagoon.