Uticaj grabuljanja na marinske ekosisteme

Fishing activity does not only impact on the fish stocks themselves, but also the ecosystem within which the fish live in. This paper presents an overview of knowledge on the effects of dredging activities on marine habitats. Dredging is used for harvesting bivalve mollusks such as oysters, clams and scallops from the seabed. The primary negative impact resulting from dredge fishing is a reduction in an abundance and diversity of seabed flora and fauna. Dredging operations inadvertently catch a range of unwanted species that are discarded into the sea. Identified dredging effects can include entrainment of organisms, increased turbidity at the dredging site, fish injury associated with exposure to suspended sediments and decreased dissolved oxygen, and fish behavioral effects due to the effects of noise. They reduce their abundance, spawning potential and, possibly, population parameters (growth, maturation, etc.). The impact on the habitat depends on the gear and sediment type. Highly dynamic, soft bottoms may suffer limited damage even when exploited by heavy (including hydraulic) dredges. On the contrary, stable, hard, and highly structured habitats will be easily damaged

Odnos otolıta ı velıčıne medıteranske skuše (trachurus medıterraneus, steındachner, 1868) u severo-ıstočnom delu Crnog mora

Mediterranean horse mackerel has an important commercial value for the Turkish fisheries. It was the second important species after anchovy in Turkey with a 115000 t production in 1986. Due to collapse of anchovy stocks since the early 1990’s, amount of catch has gradually decreased and production of horse mackerel in 2004 and 2005 decreased to 6301 t and 8287 t, respectively. It was 2651 t and 5982 t in the Southeastern Black Sea in respective years. Knowing the relationship between otolith length and fish length provides important information in determining the length of fish from the otoliths found in archaeological areas and stomach of the predators, validate ageing studies and mainly for the back calculation for the length of the rare species (Echeverria, 1987; Panfili and Tomás, 2001). Moreover, in some fish species the fish age can be determined by the otolith weight due to a high correlation existing between these two parameters (Pawson, 1990; Mardinale et al. 2000). There are no studies on ageing of Mediterranean horse mackerel in the Black Sea. There is only one comprehensive research on the relationships between otolith dimensions and fish length which has been carried out on Trachurus mediterraneus in the Sea of Marmara (Bostanci, 2009). Polat and Kukul (1990) studied ageing methods of Atlantic horse mackerel Trachurus trachurus in the Black Sea. In the present study it was aimed to derive all possible relationships between otolith dimensions and fish size using samples of Mediterranean horse mackerel caught in the South-Eastern Black Sea. These models can be used to estimate fish age from selected independent parameters especially for the routine monitoring studies for fisheries management. As a result, mean otolith length, width and weight of all samples was derived as 4.321 mm, 2.507 mm and 0.0109 g, respectively. Otolith length (OL)-otolith weight (OW), otolith length (OL)-otolith width (OWi), fish total weight (TW)-otolith weight (OW), fish length (TL)-otolith length (OL), otolith length (OL)-age (A), otolith weight (OW)-Age (A), otolith length (OL)-fish total weight (TW), otolith weight (OW)- fish length (TL), otolith width (OWi)- fish length (TL), otolith width (OWi)- otolith weight (OW) relationships were derived as OW=0.0006OL1.8971(n=394, r=0.853), OWi=0.923+0.367OL (n=551,r=0.814), OW=0.0039+0.0003TW (n=455,r=0.868), OL=1.0035+0.2458TL (n=557,r=0.811), A= 3.3398+0.4554OL (n=531, r=0.711), A=0.0051+0.0021OW (n=453, r=791), TW=0.5218OL2.473 (n=531, r=0.774), TL=8.1884+598.31OW (n=453, r=869), TL= 0.5874+5.635, OW (n=551, r=0,793), OW=0.031+5.635OWi (n=551, r=0.793), respectively. Regarding the relationships between fish and otolith size the highest correlation was found between fish length and otolith weight (r=0.869). It was also observed that there are significant differences between same relationships derived from the two research studies due to work on the samples obtained from different habitats as Sea of Marmara and the Eastern Black Sea

Strane vrste ı njıhov utıcaj na Crno more

The Black Sea, a unique fragile ecosystem, has been under the threat of pollution, climate change, invasive alien species and overfishing over many years. Combined impacts of these threats caused serious problems in the Black Sea ecosystem, fisheries economy and welfare of Turkish fishermen by reduction of the catch of commercial fish species, decrease in biodiversity, loss of habitats, increased food competition of endemic species and related problems in the food web by changes in various trophic levels. In this presentation the impacts of the alien invasive species will be explained on certain species basis in the Black Sea. Unintentionally introduced new species to a certain area are known as invasive species. Alien species that become invasive are considered to be a main direct drive towards biodiversity loss across the globe. In addition, alien species have been estimated to cost global economies hundreds of billions of dollars each year (CBD, 2011). Some of the alien species i.e. Rapana venosa, Anadara inaequivalvis, Mnemiopsis leidyi, Beroe ovata, Mya arenaria, Balanus improvisus, Mugil soiuy, Potamopyrgus jenkinsi caused significant impacts on the Black Sea ecosystem and fisheries. All kinds of impacts due to invasive species had a big effect on the reduction of total fish production in the Black Sea as predation, food competition and major destruction in the food web. There are many other species introduced to the Black Sea from phytoplankton to top predators. Some of the invasive alien species and their impacts in the Black Sea are summarized in Table 1. Research studies on the impacts of alien species to the ecosystem and fisheries economy are very limited in the Black Sea. In order to support the ecosystem recovery in spite of all types of negative impacts for the sustainable management of the natural resources, it is very essential to understand, analyze and take urgent management measures regarding all aspects of the ecosystem. New research studies in the Black Sea should be focused on prey-predator relationships, reproduction and growth rates of invasive species, relationship between their distribution and environmental factors, assessment of limiting factors, natural barriers and mechanisms, etc

Length-weight relationships of marine species caught by five gears from the Black Sea

Length-weight (L-W) relationships were presented from 10475 individuals for 19 fish, 4 mollusks, 2 crustacean species during January 2009-November 2011. The mean value of ‘parameter b’ was estimated 2.881±0.399 ranged from 1.758 to 3.616 were isometric (i.e. Scorpeana porcus, Pomatous saltatrix and Neogobius melanostomus). L-W relationships for all studied species were significantly linear (0.819<R2<0.987)

The stochastic entry of enveloped viruses: Fusion vs. endocytosis

Viral infection requires the binding of receptors on the target cell membrane to glycoproteins, or ``spikes,'' on the viral membrane. The initial entry is usually classified as fusogenic or endocytotic. However, binding of viral spikes to cell surface receptors not only initiates the viral adhesion and the wrapping process necessary for internalization, but can simultaneously initiate direct fusion with the cell membrane. Both fusion and internalization have been observed to be viable pathways for many viruses. We develop a stochastic model for viral entry that incorporates a competition between receptor mediated fusion and endocytosis. The relative probabilities of fusion and endocytosis of a virus particle initially nonspecifically adsorbed on the host cell membrane are computed as functions of receptor concentration, binding strength, and number of spikes. We find different parameter regimes where the entry pathway probabilities can be analytically expressed. Experimental tests of our mechanistic hypotheses are proposed and discussed.Comment: 7 pages, 6 figure

Weekend visitors' views and perceptions at an urban national forest park of Cyprus during summertime

Urban national forest parks provide nature preservation and recreational opportunities for socio-economically disadvantaged communities as well as tourists. We empirically examine the preferences and satisfaction of visitors in the Athalassa National Forest Park, which is located in a peri-urban area in the capital city of Cyprus. This study examines visitors' evaluation of the Athalassa in 600 face-to-face interviews during summertime weekends. A two-step cluster analysis identified two distinct clusters of visitors based on the three dimensions of satisfaction that resulted from the factor analysis and the characteristics of the visit. The dual role of the urban forest National Park was highlighted. Both local and tourist visitors were satisfied and appreciative of the setting and support services, although only the local and higher income visitors were willing to pay an entrance fee, whereas tourists avoided expressing their opinion. Management implications: This study highlighted a number of deficiencies and produced information that could be used to integrate the management decision-making process and assist in defining major lines of action for more inclusive use of urban national forest parks. The results revealed that the visitors were overall satisfied with the park, but the benefits promoted from this important green infrastructure were not evenly distributed across different sections of society with older age groups and those of lower socio-economic status were not accessing the park to the same extent as other groups, thus there is some room for improvement. However, in a time of economic crisis, the management of the park must be based on a combination of satisfying the two clusters and on improving efforts in different infrastructures.Foundation for Science and Technology [UID/SOC/04020/2013]COST Action [FP1204

Interaction forces and membrane charge tunability: Oleic acid containing membranes in different pH conditions

Oleic acid is known to interact with saturated lipid molecules and increase the fluidity of gel phase lipid membranes. In this work, the thermodynamic properties of mixed monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and oleic acid at the air-water interface were determined using Langmuir isotherms. The isotherm study revealed an attractive interaction between oleic acid and DPPC. The incorporation of oleic acid also monotonically decreased the elastic modulus of the monolayer indicative of higher fluidity with increasing oleic acid content. Using the surface force apparatus, intermembrane force-distance profiles were obtained for substrate supported DPPC membranes containing 30mol% oleic acid at pH5.8 and 7.4. Three different preparation conditions resulted in distinct force profiles. Membranes prepared in pH5.8 subphase had a low number of nanoscopic defects ≤1% and an adhesion magnitude of ~0.6mN/m. A slightly higher defect density of 1-4% was found for membranes prepared in a physiological pH7.4 subphase. The presence of the exposed hydrophobic moieties resulted in a higher adhesion magnitude of 2.9mN/m. Importantly, at pH7.4, some oleic acid deprotonates resulting in a long-range electrostatic repulsion. Even though oleic acid increased the DPPC bilayer fluidity and the number of defects, no membrane restructuring was observed indicating that the system maintained a stable configuration

Mechanisms of receptor/coreceptor-mediated entry of enveloped viruses

Enveloped viruses enter host cells either through endocytosis, or by direct fusion of the viral membrane envelope and the membrane of the host cell. However, some viruses, such as HIV-1, HSV-1, and Epstein-Barr can enter a cell through either mechanism, with the choice of pathway often a function of the ambient physical chemical conditions, such as temperature and pH. We develop a stochastic model that describes the entry process at the level of binding of viral glycoprotein spikes to cell membrane receptors and coreceptors. In our model, receptors attach the cell membrane to the viral membrane, while subsequent binding of coreceptors enables fusion. The model quantifies the competition between fusion and endocytotic entry pathways. Relative probabilities for each pathway are computed numerically, as well as analytically in the high viral spike density limit. We delineate parameter regimes in which fusion or endocytosis is dominant. These parameters are related to measurable and potentially controllable quantities such as membrane bending rigidity and receptor, coreceptor, and viral spike densities. Experimental implications of our mechanistic hypotheses are proposed and discussed.Comment: 10 Figure

In vitro in vivo relations for the parenteral liposomal formulation of Amphotericin B: A biorelevant and clinically relevant approach

There is limited information on how to perform in vitro release tests for intravenously administered parenteral formulations and how to relate the in vitro release with an in vivo pharmacokinetic parameter after the administration of the formulation. In this study, the effect of hydrodynamics (using sample and separate and continuous flow conditions) and medium components (synthetic surfactants, albumin and buffers) on the release of Amphotericin B from the liposomal Ambisome® formulation were investigated. Pharmacokinetic modeling of plasma concentration profiles from healthy subjects administered Ambisome® was used to estimate the in vivo release rate constant of drug from the formulation in order to compare it with the in vitro release profiles. With the estimated in vivo and in vitro release rate constants, release profiles were generated. Two approaches were followed: comparison of in vivo and in vitro release rate constants and comparison of the area under the percent release-time curve from observed in vitro release data and simulated in vivo release data. Albumin was found to be most critical factor for the release of the drug by having a negative effect on the amount of Amphotericin B released. The release profiles obtained with the sample and separate method in both Krebs Ringer buffer- and Phosphate Saline buffer - albumin 4.0% w/v were predictive of the in vivo release profiles in healthy subjects. Determining the factors affecting drug release from parenteral formulations and relating the release profiles to a pharmacokinetic parameter in vivo supports the development of in vitro in vivo relations for parenteral products

Gene-enhanced tissue engineering for dental hard tissue regeneration: (1) overview and practical considerations

Gene-based therapies for tissue regeneration involve delivering a specific gene to a target tissue with the goal of changing the phenotype or protein expression profile of the recipient cell; the ultimate goal being to form specific tissues required for regeneration. One of the principal advantages of this approach is that it provides for a sustained delivery of physiologic levels of the growth factor of interest. This manuscript will review the principals of gene-enhanced tissue engineering and the techniques of introducing DNA into cells. Part 2 will review recent advances in gene-based therapies for dental hard tissue regeneration, specifically as it pertains to dentin regeneration/pulp capping and periodontal regeneration