Concentrations of 17 elements in muscle, gills, liver and gonads of five economically important fish species from the Danube River

The Danube River in the vicinity of the city of Belgrade receives large amounts of untreated or poorly treated communal and industrial waste waters. The aim of this study was to assess elemental accumulation patterns in a number of economically important fish species in this area that belong to different trophic levels. Concentrations of 17 elements (Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Se, Sr and Zn) were assessedin liver, muscle, gills and gonads of silver carp (Hypophthalmichthys molitrix), freshwater bream (Abramis brama), white bream (Blicca bjoerkna), common carp (Cyprinus carpio) and wels catfish (Silurus glanis) from the Danube River in Serbia by the use of ICP-OES. Silver carp specimens were differentiated from the other four species by high concentrations of Al and Fe in the liver. Common carp specimens were differentiated by high concentrations of Zn in gills, muscle and liver. Distribution of elements among different tissues had a consistent pattern among the species. Concentrations of Pb, Cd, As, Zn, Cu and Fe in muscle were at acceptable levels for human consumption, while concentrations of Fe and Zn were above maximum acceptable concentrations in liver and gonads

Metalated N-heterocyclic reagents prepared by the frustrated Lewis pair TMPMgCl center dot BF3 and their addition to aromatic aldehydes and activated ketones

Treatment of pyridines, quinoline and methylthiopyrazine with the frustrated Lewis pair TMPMgCl center dot BF3 (1) leads to organotrifluoro borates which react readily with a variety of aromatic aldehydes in the absence of a transition metal catalyst

Demographic flexibility influences colonization success: profiling invasive fish species in the Danube River by the use of population models

Invasive species have the ability to modify their life-history traits in newly colonized areas, with positive shifts in specific life history traits under favourable environmental conditions. If such positive changes in their life history result in a comparably larger population growth rate, it may give them a competitive edge over native species, support faster range expansion and contribute to their invasion success. Within the present paper we hypothesized that the demographic flexibility represents an important contribution to the invasion success of exotic species, and that demographic flexibility patterns of invasive species differ from those in unsuccessful invaders. We tested this hypothesis by the use of elasticity analysis applied on simple age-structured population models of invasive fish species in the Danube River, as well as of non-native species that failed to establish or become invasive. Findings imply that the invasive fish species could have the ability to experience a more rapid population growth under favourable environmental conditions, especially those that sustain recruitment, while at the same time being more robust to changes in survival. The highest population elasticity among the assessed alien invasive species was detected in stone moroko (Pseudorasbora parva). The described approach has the potential to be used as an additional screening tool for invasive species. When combined with other invasion risk profiling methods, it can provide additional insight into characteristics of species invasions and in invasion potential of a species

Indicators of unsustainable fishery in the Middle Danube

Fishery in the Danube River basin has been characterised over the past century by increasing fishing levels, illegal fishing practices and poor regulations. However, there is a remarkable lack of available information on the actual status of fish stocks, as well as on the trends and sustainability of fisheries, which poses a problem for the development of adequate policy and management measures. In this study, we assessed the trends in the commercial fishery in the Middle Danube in Serbia during 1969-1989 and 2006-2010 by evaluating the temporal changes in life history-related indicators that might point out unsustainable fishing pressures. Moreover, we present the approach of using the catch-weighted mean egg-per-recruit (EPR) index as a proxy for the overall resilience of fish stocks to fishing. Results indicated a marked shift towards smaller fish that mature earlier and have a shorter lifespan. Landings also shifted towards species at lower trophic levels, with a mean trophic level decline at a rate of approximately 0.16 per decade. Results indicated likely presence of the fishing through the food web' phenomenon. At the same time, catch-weighted community mean of the 20% EPR threshold ratio (EPR20%) increased by 4.2%, indicating the increase of the overall resilience to fishing of the exploited species. Obtained results indicated the importance of using such metrics for the assessments of trends in fishery. The approach and results presented here could be of interest for the scientific community and stakeholders involved in fishery management

ELEMENTAL CONCENTRATIONS IN DIFFERENT TISSUES OF EUROPEAN PERCH AND BLACK BULLHEAD FROM SAVA LAKE (SERBIA)

Distribution of 17 chemical elements in gills, muscle, and liver of the European perch (Perca fluviatilis) and black bullhead (Ameiurus melas) from the Sava Lake (Serbia) was studied to detect bioaccumulation patterns in relation to the species' diet and trophic level. Concentrations of Ba, Cd, Co, Cr, Li, Ni, Pb, B, and Se were below the detection limits. Concentrations of Al, Fe, Mn, Sr, and Zn were higher in gills of the black bullhead; As, Mo, and Sr were higher in liver of the European perch; Fe and Zn were higher in liver of the black bullhead. In muscle, a significant difference between species was found only for Sr. Copper was detected only in liver of the black bullhead. Similarity in elemental concentrations in both species could be explained by a relatively similar diet of these two species, while the differences, especially in gills, could be explained by different habitat preferences.Ministry of Education, Science and Technological Development of the Republic of Serbia {[}TR 37009, 173045

Effects of Prenatal Dexamethasone on the Rat Pituitary Gland and Gonadotropic Cells in Female Offspring

Glucocorticoids have a strong influence on growth and maturation of fetal organ systems, but overexposure to exogenous glucocorticoids may retard fetal growth and alter developmental processes in sensitive tissues. The aim of this study was to specifically determine whether prenatal exposure to dexamethasone (Dx) altered normal development and function of pituitary gonadotropic cells in neonatal, infant and peripubertal female offspring. On day 16 of pregnancy, rat dams received 1.0 mg Dx/kg body weight (BW) s.c., followed by 0.5 mg Dx/kg BW on days 17 and 18 of gestation. Control gravid females received the same volume of saline. Female offspring were sacrificed on days 5, 16 and 38 after delivery. The volume of the pituitary gland estimated using Cavalieri's principle was significantly reduced (p < 0.05). Using a fractionator-physical disector method, we found reduced total numbers of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) cells (p < 0.05), accompanied by a decrease (p < 0.05) in serum concentrations of FSH and LH, while the relative intensity of FSH and LH immunofluorescence remained unchanged in neonatal, infant and peripubertal female offspring prenatally exposed to Dx. The data document that overexposure to Dx during fetal development evokes developmental programming of the female reproductive system at the pituitary cellular level, which may be associated with impaired reproductive function. (C) 2016 S. Karger AG, BaselMinistry of Education, Science and Technological Development of the Republic of Serbia {[}173009]; Laviefarm d.o.o., Belgrade, Serbia; Promedia d.o.o., Kikinda, Serbi

Session B7: Restoration of Longitudinal Connectivity of the Danube River by the Construction of Free Passages for Migratory Fish Species at the Iron Gates Dams

Abstract: The first impassable obstacles for the fish migration along the River Danube from the Black Sea are represented by the Iron Gates I and II hydroelectrical dams, constructed in 1972 and 1984 on 943 and 863 river kilometers, respectively. Construction of fish passages on these dams would make more than 800 river kilometers upstream reopened for fish migrations. The Iron Gates dams are jointly operated by Romania and Serbia and they represent the largest hydropower dam and reservoir system along the Danube River basin. Among migratory fish species affected by these dams are three critically endangered sturgeon species and Pontic shad (Alosa immaculata) as anadromous species, catadromous European eel (Anguilla anguilla) and more than 10 potamodromous fish species. Differences in time of upstream and downstream migrations have to be taken into account while considering the provision for free passage through the dams, as well as total lengths of upstream migrants, especially of species such as beluga sturgeon (Huso huso) that can reach total length of more than 3 m. Preliminary fish passage feasibility study could involve investigation of local hydraulic conditions at different discharges and operating conditions of dams, as well as investigation of fish behavior when they approach dams during migrations by fish tracking, telemetry, and Didson or Aris camera. Romania and Serbia could develop research teams for continual monitoring of fish behavior in the vicinity of dams, as well as in the reservoir between the two dams, based on the best experiences from other countries. Common work of biologists, ecologists, hydrologists and civil engineers is necessary regarding data collection, review of existing data, as well as for evaluation of the fish passage alternatives. Involvement of governmental agencies, local authorities, hydropower managers, researchers and NGO\u27s from both countries is one of the prerequisites for successful completion of fish passages