Biodiversity of the macrozoobenthos in some protected marine areas along Bulgarian Black Sea coast

E. Petrova*, S. Stoykov

Institute of Fish Resources, 9000 Varna, Bulgaria
(Manuscript received 30 August 2017; accepted for publication 6 November 2017)

Abstract. The aim of this paper is to establish the biodiversity status of the macrozoobenthos in some protected marine areas (NATURA 2000) along the Bulgarian Black Sea coast. The observation stations in the period 2010-2012 were within the frames of the following habitats: 1160 – Large shallow inlets and bays; 1110 – Sandbanks, slightly covered by seawater and Sublittoral mussel banks on sediment. In general, the data shows steady state compared to the 1980s, except for the area near Kamchia River, characterized by low biodiversity due to water pollution from the river inflow (with contaminants from agricultural and industrial sources in the upper river stream) and less salinity leading to marine mussel species reduction. In the border area, near the Emona zone, the black mussel catches varied between 160-600 kg in 2005, while only single specimens were detected in 2013. In the same field, the yield of Rapana venosa was within the limits of 5-40 kg in 2005 and between 80-160 kg in 2013. The established variability showed a dynamic balance between Mytilus galloprovicialis and Rapana venosa that pose a challenge for future stock of the black mussel and point the need of regular monitoring.

Taxonomic composition of phytoplankton in Black Sea area in front of the Cape Galata (2008-2016)

D. Klisarova, D. Gerdzhikov

Institute of Fish Resources, 9000 Varna, Bulgaria
(Manuscript received 13 August 2017; accepted for publication 3 October 2017)

Abstract. In this article have been investigated the taxonomic structure of the phytoplankton communities developing in the Black Sea area in front of the Cape Galata. For the period 2008 – 2016, relatively high species diversity was found (161 species). Throughout the most of the year dominated class Dinophyceae (up to 54.17%). The number of phytoplankton species decreased with distance from the shore, but the percentage participation of the group of peridineas and diatoms in the general taxonomic composition grew. Only in class Prymnesiophyceae increased biodiversity was registered in the high seas

Investigation of the biota of Burgas Bay, Black Sea

D. Klisarova*, E. Petrova, D. Gerdzhikov, S. Stoykov

Institute of Fish Resources, 4 Primorski, 9000 Varna, Bulgaria
(Manuscript received 23 March 2016; accepted for publication 30 May 2016)

Abstract. Burgas Bay is the largest one on the Bulgarian Black Sea coast. Industrial plants along the coast as well as ports for liquid and solid cargoes create conditions of anthropogenic pressure on hydrobionts in that area. Macrozoobenthos and phytoplankton samples were collected under a specific scheme in connection with the construction of the Burgas-Alexandroupolis oil pipeline, at stations located around the designated places for unloading tankers. During the study period (2009 – 2010), 88 phytoplankton species distributed in 13 classes were identified and over 50 species of benthic species distributed in four main groups: Polychaeta, Mollusca, Crustacea and the mixed group Diversa.

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Indicator polychlorinated biphenyl residues in muscle tissue of fish from Black Sea coast of Bulgaria

S. Georgieva*, M. Stancheva

Department of Chemistry, Medical University, Marin Drinov 55, 9002 Varna, Bulgaria
(Manuscript received 25 April 2016; accepted for publication 30 May 2016)

Abstract. Polychlorinated biphenyls (PCBs) are characterized by high lipophilicity and persistence in the environment and will therefore bioaccumulate and biomagnify in the food chain. PCBs were determined in muscle tissue of four fish species: goby (Neogobius melanostomus), horse mackerel (Trachurus Mediterraneus ponticus), shad (Alosa pontica pontica) and turbot (Psetta maxima maeotica). Samples were collected from Bulgarian Black Sea coast during 2007- 2011. The PCBs were analyzed in order to examine the time trends of PCB concentrations in fish from Black Sea. The six individual PCBs congeners were determined by capillary gas chromatography system with mass spectrometry detection. PCBs were found in all fish species at concentrations ranging between 2.32 ng/g ww (wet weight) and 32.87 ng/g ww in goby and shad, respectively. PCB profiles have been found to be similar in all the fish species tested. The most abundant PCB congeners in fish species were hexa- and heptachlorinated PCBs 138, 153 and 180. PCB 153 was the dominant congener in all fish studied and were found in the range from 0.95 ng/g ww (horse mackerel 2011) to 11.67 ng/g ww (shad 2010). The sum of six indicator PCBs in all fish species did not exceed the European maximum limit of 75 ng/g ww. The levels of PCBs in fish from Bulgarian Black Sea coast were found lower than in fish species from other seas – the Aegean Sea and the Mediterranean Sea.

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Application of up-to-date environmental indices for assessment of seawater

D. Klisarova*, D. Gerdzhikov, E. Petrova

Institute of Fish Resources, 4 Primorski, 9000 Varna, Bulgaria
(Manuscript received 23 March 2016; accepted for publication 26 May 2016)

Abstract. The paper discusses the indices for assessment of the ecological status of seawater which are applied in the studies of algae and macrozoobenthic communities in the Bulgarian Black Sea territorial waters. They are applicable to contemporary environmental assessments in accordance with the European directives on environmental protection. Presented are also studies carried out in recent years on marine plants and bottom organisms and the resulting conclusions. The result was that we identified the ecological status of the marine ecosystem on BQE phytoplankton, macrophytobenthos and macrozoobentos from “moderate” to “good” in the period of investigation.

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Assessment of Bulgarian Black Sea coastal water using the biological quality element phytoplankton

D. Petrova*, D. Gerdzhikov

Institute of Fish Resources, 4 Primorski, 9000 Varna, Bulgaria

Abstract. The aim of this paper was to study and assess the quality of Bulgarian Black Sea coastal water using the biological quality element phytoplankton communities, according to the requirements of the Water Framework Directive (WFD EU, 2000) and the developed reference values. A total of 134 species of microalgae were identified among which dominated the complex Bacillariophyceae/Dinophyceae (72.39 %). There was an improvement of the ecological status in three to six points from September to November 2011 (Krapetz, Shabla, Kamchiya, Dvoynitsa, Nessebar, Sozopol). This was due to the better characteristics of the phytoplankton community referring to Shannon index, number of species, Sheldon index, %MEC, DE% and Chl-a. Phytoplankton blooms were recorded in Krapetz, Varvara and Nessebar in September and in Albena, Varna-North, Sarafovo and Rosenets in November. Studies conducted have contributed to contemporary assessment of the water status in the one-mile area within the National Environmental Monitoring System (NEMS).

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Non-fish marine resources and their exploitation along the Bulgarian Black Sea coast

E. Petrova-Pavlova*
Institute of Fishing Resources Varna, 4 Primorski, 9000 Varna, Bulgaria
Abstract. Overfishing in the World Ocean including the Black Sea, as well as the global pollution led to a reduction in the quantity of industrial fish species. The occurring changes have led to the focus of fishing organizations and companies to catch some non-fish resources of economic importance. The catches help meet both the domestic market needs and increase the export list of some other marine resources. The main subject of the study are the mollusk populations of species such as black mussels (Mytilus galloprovincialis) and Rapana venosa used economically, the species form aggregations and could be subject to potential catch. The paper summarizes the results from the studies of these species in order to track the changes of their biological characteristics and to take measures for catch methods and control by the competent authorities.

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Ecological assessment of the phytoplankton community in the Bulgarian Black Sea coastal waters

D. Petrova, G. Kostadinova, D. Gerdzhikov
Abstract. The purpose of this article was to study and make an ecological assessment of the phytoplankton community in the Bulgarian Black Sea coastal waters for the period 2008 – 2010. Taxonomic distribution in the phytoplankton community is traced and analyzed on the basis of 389 quantitative and qualitative seawater samples. Dominant and subdominant phytoplankton species, qualitative and quantitative monthly and seasonal dynamics of the main groups in phytoplankton have been identified as well as their importance for the ecological status of the Black Sea ecosystem. The obtained results for phytoplankton demonstrated a comparative reduction of the trophic degree of the Bulgarian coastal waters, dominating natural factors of the environment over the anthropogenic ones and the present status of “good” and “very good” of the researched coastal area, according to the explored parameters. The phytoplankton annual development is accordingly with the climatic conditions. Also three seasonal phytoplankton successions were defined throughout the year.

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Contemporary assessment of the development of the genus Chaetoceros in the Bulgarian coastal waters

D. Petrova, D. Gerdzhikov, G. Kostadinova
Abstract. The genus Chaetoceros Ehrenberg of class Bacillariophyceae is widespread and abundant in species in the Black Sea phytoplankton. The aim of the article was to study its distribution in water and to analyzed its contemporary involvement in the formation of qualitative and quantitative composition of phytoplankton, the season dynamics of genus during the hydro-biological year and its role in the ecology of the Bulgarian Black Sea coastal water area for the period 2008 – 2010. It was found out that the highest species diversity, abundance and biomass of the genus were in the autumn and spring – a bimodal pattern of annual growth. 20 species and forms were registered of the genus Chaetoceros. They formed up to 1/3 of the taxonomic composition of Diatoms and 1/10 of all phytoplankton species. “Blooms” of representatives of the genus Chaetoceros in the researched period were not registered.

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Environmental studies of the macrozoobenthos in the nearby coastal zone along the Bulgarian Black Sea coast

E. Petrova, S. Stoykov
Abstract. The interest in studies of the nearby coastal zone of the Black Sea is great because it is the most productive section of the basin. The variety of habitats, water aeration, good temperature and density of nutrients coming from the nearest land and littoral contribute to the development of intensive life in it. In this area there are representatives of almost all groups of benthic organisms with the exception of some deep species. At the same time proximity to the coast makes it the most polluted part of the sea. Following the EU requirements pollutants are greatly reduced, which affects favourably biodiversity in the Black Sea ecosystem. 77 taxa of macrozoobenthos species were established, divided into four main groups: Polychaeta, Mollusca, Crustacea and “Diversa”. The ecological status is calculated on the Index of species diversity (H’), marine biotic index (AMBI) and multivariate Marine Biotic Index (M-AMBI). The results of the studies of macrozoobenthos from north to south in the nearby coastal area tend to improve the ecological situation in comparison with previous periods.
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