Effect of invasive ctenophores Mnemiopsis leidyi and Beroe ovata on low trophic webs of the Black Sea ecosystem

The study focuses on the impact of life excretion and mucus released by the "biological pollutants" invasive ctenophore Mnemiopsis leidyi and its predator Beroe ovata on the marine environment and lower trophic levels of the Black Sea ecosystem (bacteria, pico-phytoplankton, nano-autotrophic/heterotrophic flagellates, micro-phytoplankton, chlorophyll a, primary production (PP), micro-zooplankton). The chemical and biological variables were analysed in two sets of lab experiments with natural communities from mesotrophic (Gelendzhik) and eutrophic (Varna) coastal waters. While both species altered the chemical properties of experimental media, exerting structural and functional changes in the low food-web biological compartments, the results showed a stronger effect of B. ovata, most likely related to the measured higher rate of excretion and amount of released mucus. In addition the alterations in the Gelendzhik experiment were more pronounced, indicating that environmental implications on lower food-web are more conspicuous in mesotrophic than in eutrophic coastal waters.

A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas: The PERSEUS experience

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES.

Partial characterization of proteins from mussel Mytilus galloprovincialis as a biomarker of contamination

Preservation of a healthy environment is a very important task, especially in the time of the total industrial revolution. Therefore, attempts to find new additional biomarkers of contamination are welcomed. For this aim, the functional and antioxidant properties of mussel Mytilus galloprovincialis proteins and the heavy metals Cd and Pb were explored. Mussels were collected in contaminated and noncontaminated sites in the Varna area of the Bulgarian Black Sea coast. Proteins were extracted from mussel entire soft tissue and analyzed using instrumental (Fourier transform infrared [FT-IR] spectroscopy, fluorescence, atomic absorption spectrophotometry), and biochemical (2,2'-azinobis 3-ethylbenzothiazoline-6-sulfonate) radical cation [ABTS(.+)]) methods. It was found that mussel proteins from the contaminated sites had specific qualitative changes: partial unfolding of the alpha-helix, slight shift in amide I bands, increased hydrophobicity, and fluorescent intensity in native and denatured samples. In the same mussel samples, an increased radical-scavenging capacity and increased contents of Cd and Pb in entire soft tissue were registered. Therefore, the above-mentioned indices could be used as additional biomarkers of sea water contamination.

Application of eutrophication indices for assessment of the Bulgarian Black Sea coastal ecosystem ecological quality

The present paper is an attempt to test the applicability of the trophic state index (TRIX) for scaling the eutrophication along the Bulgarian Black Sea coastal zone in concert with a number of chemical and biological descriptors aimed at selection of relevant indicators of marine coastal area ecological quality. The following environmental parameters have been considered: t(o), salinity, nutrients--inorganic P, N and dissolved Si, dissolved oxygen and oxygen saturation, phytoplankton--taxonomic structure, abundance and biomass, chlorophyll a, zooplankton--taxonomic structure, abundance and biomass. Principal Component Analysis was applied in order to figure out and score the most relevant combination of parameters to discriminate between sites and select representative descriptors (pressure/state) of eutrophication. The following variables are defined as relevant descriptors for classification of the sites: nutrients (N, P, Si) and their molar ratios (N:P and Si:P), the capacity of the system to produce and sustain organic matter (chlorophyll a, phytoplankton biomass), phytoplankton taxonomic dominance (Bacilariophyceae:Dinophyceae biomass ratio), grazing pressure (phytoplankton:zooplankton biomass, Bacilariophyceae:Copepoda), plankton diversity index (Hb and Ha) and the trophic state index (TRIX). The investigated sites under a different anthropogenic impact are classified according to selected descriptors and their water quality state.

Beer consumption and changes in stability of human serum proteins

The aim of this study was to evaluate the influence of beer consumption (BC) on the functional and structural properties of human serum proteins (HSP). Thirty-eight volunteers (after coronary bypass) were divided into two groups: experimental (EG) and control (CG). Nineteen volunteers of the EG consumed 330 mL per day of beer (about 20 g of alcohol) for 30 consecutive days. The CG volunteers consumed mineral water instead of beer. Blood samples were collected from EG and CG patients before and after the experiment. Albumin (Alb), globulin (Glo), and methanol-precipitable proteins (MPP) from human serum were denatured with 8 M urea. Fluorescence and electrophoresis were employed in order to elucidate urea-induced conformational changes and structural behavior of proteins. The measured fluorescence emission spectra were used to estimate the stability of native and denatured protein fractions before and after BC. It was found that before BC the fractions most stable to urea denaturation were Glo, Alb, and MPP fractions. After BC in most of the beer-consuming patients (EG) some changes in native and denatured protein fractions were detected: a tendency to lower stability and minor structural deviations. These qualitative changes were more profound in MPP than in Alb and Glo. Thus, Glo is more resistible to alcohol influence than Alb, which in turn is more resistible than MPP. No serum protein changes were detected in patients of CG.

Intrinsic tryptophan fluorescence of human serum proteins and related conformational changes

The unfolding of human serum proteins (HSP) was studied by measuring the intrinsic fluorescence intensity at a wavelength of excitation corresponding to tryptophan's or typosine's fluorescence and surface hydrophobicity. The maxima emission wavelengths (lambdamax) of human serum albumin (HSA) and human serum globulin (HSG) before beer consumption (BC) were 336.0 and 337.0 nm and after BC shifted to 335.0 and 334.0 nm, respectively. The surface hydrophobicity slightly increased after BC. In a solution of 8 M urea the lambdamax of BSA shifted to 346.4 and that of BSG to 342.5 nm. In contrast, in the same solution but after BC the lambdamax positions of HSA and HSG shifted to 355.9 and 357.7 nm, respectively. A decrease in fluorescence intensity, a shift in the maximum of emission, and an increase in surface hydrophobicity which reflected unfolding of proteins were observed. Here we provide evidence that the loosening of the HSP structure takes place primarily in various concentrations of urea before and after beer consumption. Differences in the fluorescence behavior of the proteins are attributed to disruption of the structure of proteins by denaturants as well as by the change in their compactability as a result of ethanol consumption.