Institute of Fish Resources

Varna, Bulgaria

Institute of Fish Resources

Varna, Bulgaria
SEARCH FILTERS
Time filter
Source Type

PubMed | Central Fisheries Research Institute CFRI, Ukrainian Academy of Sciences, Institute of Fish Resources, National Institute for Marine Research and Development Grigore Antipa and 2 more.
Type: | Journal: Global change biology | Year: 2016

By the late 20th century, a series of events or natural experiments, for example the depletion of apex predators, extreme eutrophication and blooms of invasive species, had suggested that the Black Sea could be considered as a large ecosystem laboratory. The events resulted in regime shifts cascading through all trophic levels, disturbing ecosystem functioning and damaging the water environment. Causal pathways by which the external (hydroclimate, overfishing) and internal (food web interactions) drivers provoke regime shifts are investigated. Statistical data analyses supported by an interpretative framework based on hierarchical ecosystem theory revealed mechanisms of hierarchical incorporation of environmental factors into the ecosystem. Evidence links Atlantic teleconnections to Black Sea hydroclimate, which together with fishing shapes variability in fish stocks. The hydroclimatic signal is conveyed through the food web via changes in productivity at all levels, to planktivorous fish. Fluctuating fish abundance is believed to induce a lagged change in competitor jelly plankton that cascades down to phytoplankton and influences water quality. Deprived of the stabilising role of apex predators, the Black Seas hierarchical ecosystem organisation is susceptible to both environmental and anthropogenic stresses, and increased fishing makes fish stock collapses highly probable. When declining stocks are confronted with burgeoning fishing effort associated with the inability of fishery managers and decision-makers to adapt rapidly to changes in fish abundance, there is overfishing and stock collapse. Management procedures are ineffective at handling complex phenomena such as ecosystem regime shifts because of the shortage of suitable explanatory models. The proposed concepts and models reported here relate the hydroclimate, overfishing and invasive species to shifts in ecosystem functioning and water quality, unravelling issues such as the causality of ecosystem interactions and mechanisms and offering potential for finding ways to reverse regime shifts. We advocate a management approach aiming at restoring ecosystem hierarchy that might mitigate the costly consequences of regime shifts.


Dineva S.,Institute of Fish Resources
Bulgarian Journal of Agricultural Science | Year: 2015

In terms of water resources, important concern and one of the challenging issues will continue to be reliable seawater for a growing population, development of coastal infrastructure, and associated social and environmental activities. As the Varna Bay and the Black Sea coastal area near to Cape Galata contribute greatly to the well-being of a large number of people, in 2013, in response to social and environmental concerns, hydrological and hydrochemical research was fulfilled. This investigation promotes protection and development of the Varna Black Sea region for years to come and to be met various demands. Varna region’s seawater protection has to encompass also effective policies and management practices so that the impacts of rapid urbanization can be managed better and sustainable development for all to be achieved. © 2015, National Centre for Agrarian Sciences. All rights reserved.


Klisarova D.,Institute of Fish Resources | Gerdzhikov D.,Institute of Fish Resources
Bulgarian Journal of Agricultural Science | Year: 2015

The aim of the article is a study of the current state and growth of phytoplankton in the Bulgarian coastal waters and in the so-called „hot spots“ (Varna Bay) (2008-2010). The established average phytoplankton biomass in the coastal waters was 1.20 g/m3. Declining trend of average annual biomass and numbers from 2008 to 2010 was registered. Spring and autumn peaks typical for the post-eutrophication period were observed during the study. © 2015, National Centre for Agrarian Sciences. All rights reserved.


Uzunova S.,Institute of Fish Resources
Bulgarian Journal of Agricultural Science | Year: 2015

In 2006, 2011 and 2013 benthic macrofauna investigations were carried out in the region between Cape Kaliakra and Cape Galata, situated at 1 mile distance in front of the Bulgarian Black Sea coast and two stations in Varna Bay, so that to reveal the present situation with the benthic communities in the studied area in 2013, compared to 2006 and 2011. The results show strong increase in abundance of benthic macrofauna from 2006 to 2013 and reverse trend for the biomass values. Similar results were established for the period 1998-2002, which prove that situation within benthic community is still very unstable. Trend of decrease in mollusk’s share in species composition and increase of polychete number was found in 2013. Shannon - Wiener index shows improvement of the state of benthic communities in the investigated area. Values of Marine Biotic Index (AMBI) and multivariate AMBI (M-AMBI) are in conformity with Shannon-Wiener index and confirm the relatively good state of the ecosystem in the investigated area. © 2015, National Centre for Agrarian Sciences. All rights reserved.


Dineva S.,Institute of Fish Resources
Bulgarian Journal of Agricultural Science | Year: 2015

Lake water to fulfill vital ecosystem functions and to serve human needs is of great importance. Study of the long-term evolution of the Beloslav and the Varna lakes’ water environment has become increasingly challenging because of the significance both for a wide range of environmental and social activities and for a multi-sectoral concern. Monthly and seasonal research approach was applied to long-term investigations of key lake water characteristics that matter to broader issues like environmental protection, public and private regional business development, and stakeholder collaborations. The challenges related to the Beloslav and the Varna lakes imply environmental, social, and economic aspects to be taken into consideration that would result in more effective regulations, incentives, instruments, and investment plans in the region. © 2015, National Centre for Agrarian Sciences. All rights reserved.


Stancheva M.,Medical University-Varna | Makedonski L.,Medical University-Varna | Petrova E.,Institute of Fish Resources
Bulgarian Journal of Agricultural Science | Year: 2013

Gray mullet (Mugil cephalus) is commercially important marine school pelagic fast moving fish species especially during warm weather. The M. cephalus is an omnivore and usually inshore, entering estuaries and lagoons, like Varna Lake. The aim of the present study was to determine and compare heavy metal contents (Pb, Cd, As and Hg) in edible tissue and gills of grey mullet (Mugul cephalus). The fish samples were collected from two different Black sea areas - Varna Lake and Nesebar. The sample preparation was performed by acid microwave digestion with "Multiwave" system in five stages program. Determination of As, Cd, and Pb were carried out on a Perkin Elmer Zeeman 3030 spectrometer with an HGA-600 atomizer, whereas Hg was analyzed by Milestone Direct Mercury Analyzer. Detected levels of As in the studied regions gives exceed those of other analyzed elements. The samples from both regions showed the higher levels of As in edible tissue than gills, especially from Region of Nesebar (1.1 mg/kg w.w.). The results for other heavy metals are several times lower than arsenic and were found in range 0.01-0.12 mg/kg w.w. All studied elements (except As) presented higher amounts from Varna Lake grey mullet compared with Neserbar region samples.


Dineva S.,Institute of Fish Resources
Bulgarian Journal of Agricultural Science | Year: 2013

Recent performed hydrological and hydrochemical survey along the Bulgarian Black Sea coast has aimed to update the knowledge for principal characteristics of the water environment under climate change impact. Study of the waters along the Bulgarian Black Sea coast at 1 mile in front of Cape Kaliakra, Balchik, Albena, Cape Galata, Cape Ilandzik, Kamchia River outfall, Dvoinitsa River outfall, Cape Emine, and Nesebar was carried out in 2011. Research of Varna Bay at net of stations and of Burgas Bay at Koketrice Bank was performed. In order to investigate the influence of Beloslav Lake and Varna Lake on the Varna Bay, the Lake system was studied, as well. In-situ measurements of temperature, salinity, dissolved oxygen, and oxygen saturation were done. Some of the expected main climate change outcomes for the Mediterranean, including the Black Sea region, during the 21st century were ascertained along the Bulgarian Black Sea coast. Climate change impact on the thermo-haline structure of the Bulgarian Black Sea was found. The year's maximum sea temperature both of surface and bottom coastal waters in August 2011 was above the long-term mean, and sea temperature was with anomaly in excess of 0.87°C in the surface waters and 2.97°C in the bottom waters. Increase in salinity with 0.96 psu in the coastal waters over 2011 in comparison with 1990s was found. Salinity was above the long-term average with 2.22 psu in June. Varna Bay's salinity during 2011 was above the long-term average with 0.46 psu in the surface waters and 0.80 psu in the bottom waters. Considerable deviations of the ecosystems from the equilibrium state in both the Varna Bay and Beloslav-Varna Lake system were established. The obtained results throughout the performed survey are of key importance as to the Black Sea ecosystem function assessment along the Bulgarian coast. This research is essential for safeguarding the future security, health, well-being of human societies, marine and fish industry development, and installation of the necessary infrastructure related to appropriate facilities, as well.


Dineva S.,Institute of Fish Resources
Bulgarian Journal of Agricultural Science | Year: 2013

The world is heating up and assessment of the magnitude of temperature increases refers to the Earth's seas and oceans. The seas and oceans act as a giant rechargeable battery for the Earth. It takes a lot of energy and time to change sea temperature so that seas and oceans can be called the 'memory' of the Earth's climate system. The Black Sea in front of the Bulgarian coast becomes climate change affected area. Research in the 30-mile Black Sea zone in front of the Bulgarian coast, down to 100-m isobaths was done, with aim climate-driven changes to be established. In-situ measurements of temperature, salinity, oxygen and oxygen saturation were done. Processing of samples for nutrients was performed via unified methods for marine waters. Climate-driven transformation of the thermo-haline structure was ascertained. Because of warming, the Black Sea Cold Intermediate Layer in front of the Bulgarian coast was warmer in the frame of isotherms of 8 °C, with greatly elevated bottom border. Salinity was above the long-term average throughout the 100 m investigated layer. The greatly elevated Cold Intermediate Layer bottom border brought about rise of high-salinity deep waters. Owing to crucially reduced fresh water inputs, extremely low were the concentrations of nutrients. The organic nitrogen share was dominating at total nitrogen formation in the open-sea.


Tserkova F.,Institute of Fish Resources
Bulgarian Journal of Agricultural Science | Year: 2013

The goal of the present paper is to define some basic characteristics of the population of Black Sea sprat (Sprattus sprattus L.) along the Bulgarian cost such as size and age composition, performance and character growth, relationship between weight and length and index of Fulton. It was found that the growth in the period 2010-2012 is alometric. The values of the parameter n, characterizing the relationship between growth in weight and length, were ranging from 1.475 to 3.074. It was found that in autumn - winter season, the Fulton's index was decreasing and in the spring- summer it was increasing The parameters in the equation of Von Bertalanffy, estimated by the lengths of the periods from April to October 2011 and November 2011 - March 2012 were as follows: Lt = 12.68 {1 - exp [- 0.138 (t + 4.283)]} and Lt = 13.68 {1 - exp [- 0.267 (t + 1.975)]}.


Bekov V.,State Archive | Petrova-Klisarova D.,Institute of Fish Resources
Bulgarian Journal of Agricultural Science | Year: 2013

The aim of this article is to reveal the funds of the State Archives (SA) - Varna keeping valuable documents for the history of the first and unique Marine Biological Station with Aquarium in Bulgaria. Goals and fundamental objectives in the ecological education and research activity at the IFR-Varna are described, some specific architectural details, symbolism in them, history of important institutional changes are presented.

Loading Institute of Fish Resources collaborators
Loading Institute of Fish Resources collaborators