No abstract

Shellfish aquaculture has become an increasingly important factor in Bulgarian economy in the recent years. Marine biotoxins, produced by some phytoplankton species, may accumulate in mussels and present an important challenge in commercialization of shellfish. The aim of this study was to determine the occurrence and variability of hydrophilic toxinsparalytic shellfish poisoning (PSP) and amnesic shellfish poisoning (ASP) as well as lipophilic toxinsincluding diarrheic shellfish poisoning (DSP), pectenotoxins (PTXs) and yessotoxins (YTXs) in plankton, wild and farmed mussel samples from the Southern Black Sea coast, an important shellfish farming area in spring 2017. PSP toxins were determined by HPLC with postchromatographic oxidation and fluorescence detection and domoic acid and lipophilic toxins by liquid chromatograph coupled to tandem mass spectrometry. DA and pectenotoxin-2 were detected in plankton, wild and farmed mussel samples. Yessotoxins were detected only in cultivated mussels and no PSP toxins were detected. The occurrence of phycotoxins differed over both space and time. Toxin profile includes prevalent domoic acid, scarce presence of pectenotoxin-2 and yessotoxins in the samples.

Persistent organochlorine pollutants like polychlorinated biphenyls (PCBs) and dichloro diphenyl trichloroethane residues (DDTs) can still be a problem for the aquatic environment and human health. The levels of DDTs and PCB congeners were determined in fish from the Bulgarian Black Sea coast. Four fish species with different feeding behaviour, goby (Neogobius cephalargoides), sprat (Sprattus sprattus sulinus), horse mackerel (Trachurus Mediterraneus ponticus) and shad (Alosa pontica pontica) were sampled from the Bulgarian Black Sea coast during 2007-2010. The DDT and PCB residues were measured in clean fish extracts by gas chromatography with mass detection. The main metabolite p,p'-dichloro diphenyl dichloroethylene was the most frequently detected compound in all fish species and was present in much higher concentrations than the other DDTs (ranging from 119.32 to 1,324.44 ng/g fat). PCBs were found in all fish species at concentrations ranging between 135.1 ng/g fat in horse mackerel and 990.8 ng/g fat in goby (calculated as the sum of 15 investigated congeners). The levels of DDTs and PCBs in fish from Bulgarian Black Sea coast were comparable to those found in fish species from the Black Sea and from neighbouring seas (the Marmara Sea, the Aegean Sea and the Mediterranean Sea).

In recent years black mussels are one of the most commercially important species from the Bulgarian Black Sea. The marine mollusks are valuable healthy food, low in calories and fats and high in proteins. They are a major dietary source of fat soluble pigments - astaxanthin, carotenoids and polyunsaturated fatty acids (PUFA). To our knowledge the information about the nutritional quality of mussels from the Bulgarian Black Sea waters, based on chemical composition, fat soluble pigments, cholesterol and PUFA content is very limited. The aim of the present study is to determine and compare protein, lipid, carbohydrate and energy values, fat soluble pigments, cholesterol and fatty acid composition in farmed mussels (Mytilus galloprovincialis) from the Bulgarian northern and southern parts of the Black Sea coast. The mussel samples were analyzed for lipids (Bligh & Dyer method), crude proteins (Kjeldahl method), carbohydrates and moistures according to the AOAC (1990) methods. Fatty acids were analyzed by the GC-MS system. Fat soluble pigments and cholesterol were analyzed simultaneously by the RP-HPLC system. Lipid and protein content were found to be higher in mussels from the northern region. In accordance with the Commission Regulation (EC) No. 116/2010 all analyzed mussel samples can be classified as high in protein and low in fats and carbohydrates. The amount of cholesterol, contained in all mussel populations is significantly low, while the omega-3 (n-3) is significantly higher than the omega-6 PUFA. A portion of 100 g edible tissue provides 0.500 g more of the required amount of eicosapentaenoic acid (20:5) and docosahexaenoic acid (22:6) n-3 PUFA according to EFSA (2012). It can be concluded that the studied mussel aquaculture in the Black Sea is beneficial food for the human health and it is advisable to be part of a proper or a preventive diet of Bulgarian consumers.

Organochlorine pesticides (such as 1,1,1-trichloro - 2,2 - bis (4-chlorophenyl) ethane (DDT) and its metabolites) and polychlorinated biphenyls (PCBs) are classified as Persistent Organic Pollutants (POPs) and are present in the contamination pattern of marine environments world-wide. Concentrations of PCBs and DDTs were measured in two marine species: garfish (Belone belone) and red mullet (Mullus barbatus). Samples were collected from Black Sea, Bulgaria during 2007 - 2010. The DDTs and PCBs were determined by gas chromatography - mass spectrometry. Concentrations in muscle tissue of garfish ranged from 80.89 to 118.04 ng/g wet weight for total DDTs. DDTs concentration in red mullet was found 104.59 ng/g ww. PCB concentrations in garfish varied in the range of 40.04 and 65.62 ng/g ww. In muscle tissue of red mullet PCB concentrations were found 34.12 ng/g ww. The levels of DDTs and PCBs in garfish and red mullet from the Black Sea were comparable with those found in other marine ecosystem.