Environmental impact of fish farming: assessment of metal contamination and sediment geochemistry at three aquaculture areas from the eastern Aegean coast.

Metal contamination and geochemistry of surface sediments were assessed at three aquaculture sites from the eastern Aegean coast. The chlorophyll degradation products and organic carbon levels were used as indicators of eutrophication status. In Akköy, higher Hg, Pb, and Cd levels were observed around the cages, while maximum concentrations of other elements were determined at stations situated near the Büyük Menderes River estuary. Metal concentrations were less than the central Aegean coast background levels other than Zn, Ni, and Cr in Akköy. Several approximations have been utilized to evaluate potential toxicity of sediments and sediment quality guidelines (SQG) were used to estimate the risks for aquatic life. Ni was the only metal with concentrations exceeding all SQG values, which indicates the highest adverse biological effect in Ildir, Akköy, and occasionally toxic in Güllük. Based on QPEL and QTEL, Ni and Cr were the predominant metal contaminants in all areas. Similarly, Cr and Ni account for the most of the all sediment toxicity in the aquaculture areas according to toxic risk index. It is concluded that sediments around the fish farms are affected by growing input of elements because of aquaculture activity. The levels of chlorophyll degradation products showed oligotrophic and mesotrophic conditions in the three studied aquaculture areas.

Environmental factors influencing the abundance and spatial distribution of modern dinoflagellate cysts in Izmir Bay (Eastern Mediterranean).

We analyzed surface sediments from 12 stations located in Izmir Bay to determine the impact of anthropogenic pollution on dinoflagellate cysts. Forty-three dinoflagellate cyst taxa and two cyst assemblage zones were identified. Zone 1 is characterized by the dominance of cysts of Gymnodinium nolleri, Selenopemphix nephroides, and Operculodinium centrocarpum from the oligotrophic part of Izmir Bay. Zone 2 is in the highly productive inner part of the bay and is characterized by the high abundances of Lingulodinium machaerophorum, Spiniferites ramosus, cysts of Scrippsiella spp., cysts of Polykrikos spp. and Quinquecuspis concreta. We used multivariate statistical analysis (DCA and CCA) on dinoflagellate cysts and environmental variables to support the identification of Zones 1 and 2. Our analyses also revealed that summer and winter chlorophyll-a as well as elevated nitrate and nitrite concentrations are significant parameters in controlling dinoflagellate cyst distribution in Izmir Bay.

Heavy metal concentrations in surficial and core sediments from Izmir Bay: an assessment of contamination and comparison against sediment quality benchmarks.

The levels of heavy metals were determined in surface and core sediments from the Izmir Bay in 2009. The highest concentrations of As, Cr, Cu, Ni, Pb and Zn were found in the inner bay due to industrial activities. In contrast, maximum levels of Mn, Co, Fe and Al were observed in the outer bay, due to geochemical structure. Cu, Pb, Zn, Ni, As, Cr and Co levels in the upper layer of core sediments were higher than the mean background values of bottom sediments. The enrichment of Cr, Mn, Pb, Zn, Cu and As in the bay seems to be driven by anthropogenic sources. It was found that the sediments in Izmir Inner Bay were generally polluted heavily with Cu, As, Ni, Cr, Pb and moderately with Zn according to the numerical Sediment quality guidelines of the USEPA.

Multi-index assessment of sea bottom sediments of the Izmir Gulf, Aegean Sea: A study of interrelation between anthropogenic and hydrodynamic effects.

This study aimed to investigate the sediment transport pathways and geochemical parameters in the Izmir Gulf to determine the heavily impacted areas by natural and anthropogenic parameters. The grain size trend analysis was used to determine sediment transport patterns and, statistical methods were employed to identify the sources and distribution of chemical elements in sediments. The main factors that were affecting the area were identified as lithogenic, anthropogenic, maritime traffic, biogenic and shipyard activities. The tannery industry (Cr), maritime traffic and shipyard/dock activities (Cu and Zn), road traffic run-offs (Pb and Zn), and untreated domestic waste discharges (TOC and S) were identified as the sources of metals. Contamination rankings based on metal concentrations indicated higher pollution levels in the Inner Gulf compared to the Central Gulf. Zinc and chromium were found to pose significant risks to benthic organisms. The pollutants tended to accumulate in deposition zones, following sediment transport directions.

Metal levels in sediments and caged mussels in one of the industrial zones of the Eastern Aegean Sea.

Caged mussels make biomonitoring studies possible with their ability to take up pollutants in the industrial zones. The goal of this study was applied to assess metal levels in the biomonitoring organism Mytillus galloprovincialis Lamark, 1819 for transplantation from three locations for two periods (2016-2018) in the industrial zone of the Eastern Aegean Sea. Metals were also determined in sediments; high concentrations of Hg, As and Zn in surficial sediments of Nemrut Bay can cause hazardous impacts on the aquatic environment with respect to sediment quality guidelines. The highest contamination factor (Cf) was calculated for Hg (Cf = 10), suggesting serious anthropogenic pollution in the study area. According to Pearson product-moment correlation analysis, As is not correlated with other metals due to As mainly originating from natural sources. Hg, Cd, Pb and Cu concentrations increased in the transplanted mussels during a field transplant experiment because of chronic pollution from industrial activities. Cumulative effects of both the oil refinery and shipbreaking industry cause higher uptake of Hg, Cd, Pb and Cu in sampling station 3 as a result of higher exposure levels in transplanted mussels. Mussel consumption was compared with provisional maximum tolerable intake from literature; the estimated provisional intake (EDI) for Cd, Hg and Pb does not exceed maximum levels; however, Cu and Zn exceed reference EDI values. Since Nemrut Bay is heavily influenced by industrialisation, it is not a suitable region for seafood production.

Variations in copepod composition and diversity in relation to eutrophication and hydrology in Izmir Bay, Aegean Sea.

Hyrographic and trophic gradient along Izmir Bay used to assess their effects on the copepod composition and diversity. Trophic state of the bay varied from oligotrophic in the outer region to hypertrophic condition in the inner region as stated by trophic index (TRIX). Aegean Sea water entrance and trophic conditions of the bay affected species assemblages. Oithona davisae, Oithona nana and Acartia clausi were associated with hyper-eutrophic conditions whereas the typical Aegean Sea species, such as Oncaea media group, Oithona similis, Paracalanus parvus, A. clausi, Farranula rostrata and Calocalanus styliremis were related to oligotrophic condition. Copepod diversity indices decreased linearly along the trophic gradient, from oligotrophic to hyper-eutrophic conditions, highlighting the substantial impact of eutrophication on the copepod community structure in the inner region. These findings emphasize TRIX's value in assessing eutrophication in anthropized systems, and immense potential for using copepod composition and diversity in monitoring programs for ecological assessments studies.

Distribution of aliphatic and aromatic hydrocarbons in red mullet (Mullus barbatus) and annular sea bream (Diplodus annularis) from the Izmir Bay (eastern Aegean).

Polycyclic aromatic and aliphatic hydrocarbons were analyzed in red mullet and annular sea bream from the Izmir Bay. These fishes were selected because of their multitude, wide distribution and common use in the Turkish diet; they were sampled and analyzed in 2000-2001 and 2004-2005 periods at five locations by trawling. Red mullet showed higher PAHs and aliphatics than annular sea bream. PAH levels for red mullet and annular sea bream ranged from 202 to 556 and 78.7 to 415; aliphatics ranged from 834 to 2,420 and 436 to 1,724 ng/g dw, respectively. Molecular ratios showed pyrolitic inputs for PAHs, biogenic and anthropogenic inputs for aliphatics. The carcinogenic PAH, benzo(a)pyrene, was detected in most fish samples in levels ranged between 22.2 and 64.1 ng/g dw. The average PAH contamination level was within the "moderate" category in fish from Izmir Bay. Results indicate the needing of a systematic monitoring program in order to provide accurately assessment and management of risks for the regional population.

Assessment of metal concentrations in sediments from Lake Bafa (Western Anatolia): an index analysis approach.

Metals, organic carbon contents were determined in surficial and core sediment samples from Lake Bafa, Western Anatolia in 2010. The ranges of Fe, Mn, Pb, Cu, Ni, Cr, Zn and Hg contents of sediments from the Bafa Lake were 9.4-35 g kg(-1), 250-780, 2.3-20, 5.8-55, 1.2-480, 63-278, 26.6-79.9 and 0.013-0.273 mg kg(-1), respectively. The mean metal concentrations in surficial sediments obtained in this study decreased in the following order; Fe > Mn > Ni > Cr > Zn > Cu > Pb > Hg for Bafa lake. Total organic carbon concentrations of the bottom sediments from the Bafa Lake varied between 0.35% and 3.58%. The mean concentrations of metal were lower than the background levels in earth crust except Cr and Ni in the core sediments. The metal levels were evaluated according to the New Geo-accumulation Index, enrichment and contamination factors. The results confirmed that the Bafa Lake is not facing serious environmental pollution risk due to metal contamination except Hg. The levels of Cr, Ni, Cu, Fe, Zn and Mn generally appear to be uniformly distributed with depth except Hg and Pb due to anthropogenic sources in the core sediments.

Combining single and complex indices of pollution with grain size trend analysis of surficial sediments in Edremit Gulf, western Turkey.

Pollution risk assessment of heavy metals (Pb, Cr, Cu, Ni, Zn, As) in sediment samples from 68 locations in the Gulf of Edremit, western Turkey, was performed using single and complex indices of pollution assessment approaches. The pollution indices used in the sediment analyses included pollution load index, contamination factor, contamination degree for individual metals, geoaccumulation index (Igeo), enrichment factors, toxic risk index, modified pollution index, frequency of adverse biological effects (TEL-PEL), percent incidence of biological effects (ERL-ERM), and total risk quotients. Results indicated a low degree of contamination for the entire surveyed area except moderate contamination factor for arsenic using single indices. Enrichment factors and geoaccumulation indices indicated moderate to significant enrichment and uncontaminated to moderately contaminated both for arsenic (As) and lead (Pb), respectively. According to the results of ecological risk assessment based on TELs and PELs, the adverse biological effects of heavy metals on aquatic organisms; are for As, Cr, Ni frequently, Cu and Pb occasionally, and Zn rare. The toxic risk index values displayed low to considerably toxic risk for the entire Gulf and calculated toxic risk index results showed that arsenic accounted for most of the entire sediment toxicity. Transport patterns of sediment grain size trend analyses were correlated with the results of pollution assessment models. Transport trends are compatible with the sources of lithogenic, anthropogenic, mining activities and wastewater treatment/geothermal originated arsenic.

The water quality of Izmir bay: a case study.

About 30 studies from the published literature were reviewed to determine the status of several categories of pollutants (i.e., nutrients, heavy metals, and organic compounds) in the Izmir Bay. The Izmir Bay of western Turkey is one of the great natural bays of the Mediterranean Sea. The city of Izmir is an important industrial and commercial center and is a cultural focal point for this area. In this review, I review the results of studies performed by researchers over a period of two decades to glean what probable impact has resulted from human activities in the bay. I also summarize available data on the contamination levels found in the bay and the effects generated by these levels on the ecosystem of the bay. In addition, I provide a monitoring analysis that provides the distribution of inorganic nutrients and chlorophyll-a that have been investigated and the N/P ratios that were determined in Izmir Bay during 1996-2008. To identify the temporary trends in the monitoring data, linear regression analyses were performed. Significant negative trends were observed in TNOx concentrations in Izmir Bay. No significant trend was found in metal concentrations except Pb in the sediment. A significant negative existed for Hg in fish. Unfortunately, there are only limited data available for the organic contaminations from Izmir Bay. Therefore, any attempt to create a regional scale assessment from organic contaminant data available in the literature is limited by the scarcity of available information.

The impact of fish farming on the water column and marine sediments in three coastal regions from eastern Aegean coast.

The impacts of mariculture activities in the water and sediments were comprehensively evaluated for the first time in this study. Lower dissolved oxygen was detected near the cages during summer due to aquacultural activities and bacterial degradation of organic compounds. However, DO levels were not below the 5 mg L-1 limit recommended for aquatic growth, survival and metabolic processes. Different eutrophication assessment methods showed that Güllük Bay, where intensive aquaculture activities occurred, was characterized by poor status. Assessment of different eutrophication tools for Akköy and Ildir Bay indicated that water quality status was not similar to each other. The most noticeable effect of aquaculture activities is the sedimentation of faeces and uneaten food under the cages. Nutrients in the water indicated gradual decrease with distance from the cages. Comparison of total phosphorus in sediments showed that the most affected area is Güllük Bay owing to cumulative impact of aquaculture. The higher total organic carbon (TOC) in sediments was measured near and under the cages. TOC was a useful indicator to show benthic health, less than 10 mg g-1 corresponded to low risk deteriorations for all aquaculture sites. Sediment monitoring studies should be carried out to provide sustainable use of the aquaculture areas.

Monitoring metal contamination levels and fecal pollution in clam (Tapes decussatus) collected from Izmir Bay (Turkey).

The aim of this study was to monitor the heavy metal contents and fecal pollution in Tapes decussatus (carpet shell clam) from Izmir Bay (Eastern Aegean). Bivalve mollusks were sampled on January, March, July, and October 2007 in the Izmir Bay. Izmir Bay is one of the great natural bays of the Mediterranean. Concentrations of heavy metals were determined in the clams from the different seasons. Fecal coliform densities were determined to evaluate the degree of water pollution and clams' microbiological accumulation of the classical microbial pollution indicators. The concentration of heavy metals in T. decussatus from Izmir Bay were Hg 0.044-0.13; Cd 0.026-0.24; Pb 0.38-1.2; Cr 2.3-3.7; Cu 6.4-8.4; Zn 56.0-81.8, and Ni 8.1-9.6 microg/g (dry weight). The maximum values were generally obtained in July and March except Ni. This study found that the levels of heavy metals except Cr in T. decussatus were below Spanish and European Communities legislations for shellfish as food. Microbial pollution indicators (heterotrophic bacteria and fecal coliform) were measured in T. decussatus. Maximum heterotrophic bacteria and fecal coliforms were recorded in the winter while the lowest were detected in summer.

Assessment of trace metal pollution in surface sediments of Nemrut Bay, Aegean Sea.

Surface sediments collected from nine stations in Nemrut Bay, Aegean Sea were analyzed for trace metals (Hg, Cd, Pb, Cr, Cu, Zn, Mn, Ni, Fe, As, and Mg) and grain sizes. The results were compared with the numerical sediment guidelines used in North America as well as literature values reported for similar studies conducted in Izmit Bay and Izmir Bay. The metal levels were also evaluated according to the enrichment factor and contamination factor analyses. The analyses revealed significant anthropogenic pollution of Hg, Pb, Zn, and As in the surficial sediments of Nemrut Bay.

Levels and distribution of polychlorinated biphenyls in two edible fish species from Izmir Bay (eastern Aegean): a health risk assessment.

The concentrations of polychlorinated biphenyl (PCB) congeners were examined in two fish species from the Izmir Bay. A total of 624 individuals of different fish samples were sampled by trawling from three regions in Izmir Bay between 2010 and 2013. The total levels of indicator PCBs in all samples varied LOD (limit of detection) to 34.3 ng g-1 (dry weight) in the study area. The highest concentrations of PCBs were found in Gulbahce for Mullus barbatus and Diplodus annularis in 2011 and 2010, respectively. PCB153 was the major contributed congener in both fish species during sampling periods. Principal component analysis (PCA) was performed to evaluate the correlation of the determined variables in fish species. According to PCA, the PCBs are not related with fish length. One-way ANOVA test indicated that significant temporal variations were generally detected for PCBs, while non-significant spatial variations were examined between sampling sites. Six PCB congeners were found as 0.59-6.64 ng g-1 (wet weight, wwt) and compared with iPCB6 limits of 75 ng g-1 (wwt) revealed by the Environmental Food Safety Authority. Accordingly, all fish species analyzed did not surpass the safe limits of iPCB6 suggested by EU. The estimated daily intake of 6 PCB congeners by the people were less than the tolerable daily intake (TDI, 10-ng kg-1 body weight day-1) recommended by WHO (2003), suggesting that this intake would not cause adverse effects to residents of Izmir.

Monitoring of polycyclic aromatic hydrocarbons in transplanted mussels (Mytilus galloprovincialis) and sediments in the coastal region of Nemrut Bay (Eastern Aegean Sea).

Polycyclic aromatic hydrocarbons (PAHs) were determined in the coastal region of Nemrut Bay, Eastern Aegean. Sediment and caged mussels were evaluated for sixteen PAHs. High contamination was observed in the sediment sampling sites next to the petrochemical refinery. Low molecular weight PAH levels were dominant in the sediments and the ratio LMW/HMW were higher than one, indicating petrogenic origin pollution. The m-ERM-q values of the sediments were classified as high-priority sites near the refinery while other sites were categorized as medium-low sites. 4-ring PAHs were found to be dominant in the mussels. PAHs were originated from petroleum and mixed sources (petrogenic, pyrogenic) both two transplantation experiments. The assessment of human health risk based on the Carcinogenic `Toxic Equivalents suggested that the mussels have high capability to give rise to carcinogenic risks. PAH levels in the mussels were above the Recommended Total Carcinogenic PAH limits set by the European Union.

Impact of environmental variables on fouling bryozoan species in the Eastern Aegean Sea.

Bryozoans are the major component of marine macro-fouling communities. In the study, the relations between bryozoan species and environmental variables were investigated at seven stations along the Aegean coast in August and December 2015. Constant bryozoan species in both sampling periods were Bugula neritina, Amathia verticillata, Shizoporella errata, Cryptosula pallasiana and Celleporaria brunnea. Their relationship with physico-chemical variables (Temperature, salinity, pH, dissolved oxygen, ammonium, nitrite and nitrate nitrogen, orthophosphate phosphorous, total phosphate, chlorophyll-a) were analysed by means of logistic regression analysis. The result showed that temperature with B. neritina; NH4-N, oPO4-P and TPO4-P with A verticillata; dissolved oxygen concentrations with S. errata and C. brunnea were positively related (p < 0.05).

Levels, distribution, and ecological risk of organochlorines in red mullet (Mullus barbatus) and annular sea bream (Diplodus annularis) from the Gulf of Izmir, Eastern Aegean, in 2009-2012.

Organochlorine (OCs) concentrations were measured in two fish species, Mullus barbatus and Diplodus annularis, collected from Izmir Gulf during 2009-2012 in order to explain the status of these contaminants in edible fish. No data is available on the levels of organochlorines in marine organism from Izmir Gulf. In both fish species from the study area, Aroclors were determined in higher concentrations than organochlorine pesticides (OCPs). Maximum concentrations of OCPs and PCBs measured in the edible part of D. annularis were 45-165 and 530-1591 ng g-1 lipid weight (lw), respectively. DDTs (sum of DDT and metabolites) and cyclodienes ranged from 4-56 to 16-110 ng g-1 lw, respectively. The levels of DDTs measured in the present study were generally comparable or lower than those found in studies from other Mediterranean and non-Mediterranean regions. The potential risks for fish consumers were assessed. Although the estimated daily intake (EDI) for DDTs, heptachlor, and drins through the sampled fish species by Izmir inhabitants was quite lower than the ADI (acceptable daily intake) established by the FAO/WHO, EDI for Aroclor 1254 was close to the ADI value of 20 ng g-1 recommended by the IPCS (2000).

Persistent organochlorine residues in fish and sediments collected from Eastern Aegean coast: Levels, occurrence and ecological risk.

Organochlorines were determined in fish and sediment collected from Izmir and Çandarli Bays. The results indicated that ΣCyclodiens were generally predominant contaminants. In all samples, p,p'-DDE was the predominant DDT congener. Aroclors were found in noticeably higher levels than OCPs in sediment and the highest levels of Aroclors, OCPs were found in Nemrut which can be attributed to industrial activities. According to Sediment Quality Guidelines, DDTs were lower than the values that may cause adverse biological risk in sediment samples. Aroclor 1254 in sediments only exceeded the TEL value at Nemrut site. The maximum values of ΣOCPs were found in fish collected from Gülbahçe, while Aroclors were measured in Aliaga. According to related indices, results indicate no recent influxes of DDT in the sampling areas. The estimated daily intake of DDTs, Aroclor1254 were below the acceptable daily intake level recommended by FAO/WHO.

Potential risk assessment of metals in edible fish species for human consumption from the Eastern Aegean Sea.

The levels of Hg, Cd, Pb, Cr, Cu and Zn were measured in the tissues of four edible fish species namely: Diplodus annularis, Pagellus erythrinus, Merluccius merluccius and Mullus barbatus, collected from the Turkish Coast of the Aegean Sea. Except for D. annularis, the levels of Cd and Pb in all fish tissues sampled in Aliaga Bay in 2009 were above the tolerable limits according to the Food and Agriculture Organization of the United Nations (FAO). Hg in P. erythrinus and M. barbatus were higher than the maximum permitted limits (FAO), while D. annularis and M. merluccius were lower than the limit for biota in the district of Aliaga. Although the Target Hazard Quotient (THQ) values for Cd, Pb, Cu, Cr, Zn in all fish samples were lower than 1.0, the THQ for Hg levels were higher than 1.0 for most of the samples. According to the THQ values, M. merluccius may be consumed in moderation from Aliaga Bay, while the consumption of M. barbatus and P. erythrinus collected from Aliaga Bay are potentially hazardous to human health due to the Hg concentrations. Fish collected from Izmir Bay can be consumed safely.

Marine pollution risk in a coastal city: use of an eco-genotoxic tool as a stress indicator in mussels from the Eastern Aegean Sea.

Coastal areas, such as bays, estuaries, and harbors, are heavily polluted since these areas are the settlements to which toxic chemicals from industrial and domestic wastes are discharged. The genetic damage was evaluated using bioindicator mussel Mytilus galloprovincialis caused by toxic chemicals (metals and polycyclic aromatic hydrocarbons) in Izmir and Çandarli Bays (the Eastern Aegean Sea) through comet assay. Three sampling sites from the two bays were selected and the study was conducted during the spring and autumn periods. The highest levels of DNA damage expressed as %Tail-DNA were observed in Izmir Bay (34.60 % Tail-DNA) in the spring. Analysis of the correlation between PAHs and metals in mussels and %T-DNA in the hemolymph and gill cells showed a statistically significant positive correlation between %T-DNA and ∑PAH, chromium (p < 0.05). This study determined the pollution level of the Izmir and Çandarli Bays by using the DNA damage to the mussel, which can identify the effects of environmental pollutants at the cellular levels. These results confirm that comet assay can be used to determine the temporal and spatial differences of DNA damage, and as a suitable tool for the measurement of genotoxicity in regions with low pollutant concentrations.