Seasonal variations and human health risk assessment of trace elements in the bivalve ecosystem in the Sea of Marmara.

Twelve trace elements were studied in four economically important bivalve molluscs (Mediterranean mussel, manila clam, striped venus clam, and truncated wedge clam) from the southern Marmara Sea for seasonal bioaccumulation and human health risk assessment. According to the findings, Fe and Zn were the most accumulative and element concentrations changed considerably (P < 0.05) between seasons and species. Daily, weekly, monthly intake and target hazard quotients of the trace elements were estimated and compared with maximum limits. The results revealed that consuming these bivalve molluscs from the southern Marmara Sea could be considered safe for human consumption. Nevertheless, further monitoring is needed in order to better follow the development in time of elemental pollution due to increasing environmental pressure on the Marmara Sea basin, together with research on other different bioaccumulative organisms.

Levels of PAHs, PCBs, and toxic metals in Ruditapes philippinarum and Donax trunculus in Marmara Sea, Turkey.

BACKGROUND: The manila clam Ruditapes philippinarum and the wedge clam Donax trunculus are economic bivalve species which constitute an important part of the natural bivalve beds in the Marmara Sea, Turkey. Toxic chemicals such as, dioxins, dioxin-like polychlorinated biphenyls (PCBs), polycyclic hydrocarbons (PAHs), and toxic metals are recognized as important health risk factors that threaten public health via food or directly in the environment. In the present study, we aimed to determine and monitor levels of these toxic chemicals in both clam species, R. philippinarum and D. trunculus, between 2013 and 2017. RESULTS: According to the results, maximum levels of dioxins, PAHs, and toxic metals (lead, cadmium, mercury) during the period were determined as 0.18 pg g-1 , 2.43 mg kg-1 , and 0.44-0.53-0.1 mg kg-1 , respectively. The level of contaminants in both clam species were determined to be below the threshold or tolerable daily intake values established by the European Commission, European Food Safety Authority (EFSA), and Food and Agriculture Organization/World Health Organization (FAO/WHO). Seasonal fluctuations were observed to be similar in both species and also in seasons, but elevated levels of PCBs and PAHs were detected in warmer months during the period. CONCLUSION: As a consequence, toxic chemicals in both clam species were found at low concentrations in this study from the point of view of public health concerns; however, the contaminants should be closely monitored in the future due to their elevated levels in samples. © 2020 Society of Chemical Industry.

Depuration Times of Donax trunculus and Tapes decussatus.

The present study was performed to determine the depuration time and ability of Donax trunculus (Wedge Clam) and Tapes decussatus (Carpet Shell) contaminated with Escherichia coli, Salmonella enterica subsp. enterica serovar Typhimurium and Vibrio parahaemolyticus. Clams were contaminated with each bacterium at the level of 7.0 - 8.0 Log10 cfu/g. After contamination, clams were analyzed every 3 h in the first 24 h time period and every 6 h until the 72nd hour. During the depuration process of both clams, the level of bacteria decreased quickly to 40% of initial load in the first 12 h. The results of this study indicate that the depuration time of carpet shells for all bacteria is 66 h. The depuration process of the wedge clam was different from the carpet shell; S. typhimurium and E. coli can be depurated in 66 and 78 h, respectively, while V. parahaemolyticus was present after 72 h at the level of 1.7 Log10 cfu/g.

Depuration Times of Donax trunculus and Tapes decussatus

The present study was performed to determine the depuration time and ability of Donax trunculus (Wedge Clam) and Tapes decussatus (Carpet Shell) contaminated with Escherichia coli, Salmonella enterica subsp. enterica serovar Typhimurium and Vibrio parahaemolyticus. Clams were contaminated with each bacterium at the level of 7.0 - 8.0 Log10 cfu/g. After contamination, clams were analyzed every 3 h in the first 24 h time period and every 6 h until the 72nd hour. During the depuration process of both clams, the level of bacteria decreased quickly to 40% of initial load in the first 12 h. The results of this study indicate that the depuration time of carpet shells for all bacteria is 66 h. The depuration process of the wedge clam was different from the carpet shell; S. typhimurium and E. coli can be depurated in 66 and 78 h, respectively, while V. parahaemolyticus was present after 72 h at the level of 1.7 Log10 cfu/g.

Proximate and elemental composition of Chamelea gallina from the southern coast of the Marmara Sea (Turkey).

The venerid clam Chamelea gallina is a popular and economic foodstuff around the Mediterranean countries especially in Italy, Spain, and France. The aim of this study is to evaluate the nutritional quality of striped venus of Southern Marmara. Samples were harvested seasonally at five stations and analyzed to determine meat yield, proximate, and elemental composition. According to the results, meat yield ranged from 20.24% to 29.94%. Means of water, protein, lipid, and ash content were 67%, 10.12%, 2.57%, and 1.66%, respectively. The mean concentrations (mg/kg wet weight) of elements in tissues are as follows: B: 2.37-4.24; Cr: 0-0.76; Co: 0-0.43; Cu: 0.71-5.30; Mn: 0.30-5.94; Zn: 13.08-77.76; Ni: 0-1.22; Fe: 2.46-114.22; Al: 1.23-75.49; Pb: 0.18-3.24; Ba: 0.66-15.97; Cd: 0.04-0.69. Among the reported metal levels, only Pb and Zn in two stations exceeded the maximum critical concentrations enforced by Turkish legislation and European Commission. Therefore, we report that striped venus from Southern Marmara Sea, in general, are safe for human consumption; nonetheless, Pb and Zn levels should be closely monitored in the future.

Gross pathology, blood chemistry, lipid and peroxide contents in rainbow trout ( Oncorhynchus mykiss Walbaum) affected by experimental Arcobacter cryaerophilus infection at low water temperature.

Arcobacter cryaerophilus was isolated from naturally infected rainbow trout ( Oncorhynchus mykiss Walbaum), and its pathogenicity was tested by intramuscular injection using healthy 1-year-old rainbow trout under cold-water conditions (at 5 degrees C). The lethal dosage of 50% end point (LD 50 ) for A. cryaerophilus was calculated as 7.79 x 10 5 viable cells. Experimental infection caused gross clinical abnormalities such as fallen scales, exophthalmia, oedema in injection region and at the base of fins, pale gills, kidney necrosis, hyperaemic areas in pale liver, haemorrhagic spots in heart, elongated spleen and swollen gallbladder. Activities of aspartate aminotransferase and alkaline phosphatase, and concentrations of glucose, total protein, albumin, cholesterol, triglyceride and calcium in the serum of the experimentally infected rainbow trout were significantly decreased compared with the healthy fish. Positive correlations were observed among blood parameters. Total lipid weights increased in the brain, muscle and liver tissues of infected fish and dropped in the gill and spleen tissues. Lipid peroxide contents in the brain, liver, kidney, spleen, muscle and gill tissues of infected rainbow trout were significantly higher than in healthy animals. The present work shows that A. cryaerophilus can be moderately virulent for rainbow trout at low water temperature, and changes in lipid and lipid peroxide contents of tissues and blood indices can highlight barely detectable effects of A. cryaerophilus infection in rainbow trout under laboratory conditions. However, the application of these indices in farm biomonitoring using rainbow trout will need more detailed studies and a careful consideration of the environmental parameters.