1,531 research outputs found
Turbulence and stratification in Priest Pot, a productive pond in a sheltered environment.
No full textPriest Pot is an example of the abundant ponds which, collectively, contribute crucially to species diversity. Despite extensive biological study, little has been reported about the physical framework which supports its ecological richness. This paper elucidates the physical character of Priest Pot�s water column and thus that of similar waterbodies. Vertical thermal microstructure profiles were recorded during summer 2003, and analysed alongside concurrent meteorological data. During summer stratification, the thermal structure appeared to be dominated by surface heat fluxes. Surface wind stress, limited by sheltering vegetation, caused turbulent overturns once a surface mixed layer was present, but appeared to contribute little to setting up the thermal structure. Variations in full-depth mean stratification occurred pre-dominantly over seasonal and ~5-day time scales, the passage of atmospheric pressure systems being posited as the cause of the latter. In the uppermost ~0.5 m, where the stratification varied at sub-daily time scales, turbulence was active (sensu Ivey and Imberger, 1991) when this layer was mixed, with dissipation values � ~ 10-8 m2s-3 and vertical diffusivity KZ = 10-4-10-6 m2s-1. Where the water column was stratified, turbulence was strongly damped by both buoyancy and viscosity and KZ was an order of magnitude smaller. Vertical transport in the mixed layer occurred via many small overturns (Thorpe scale rms and maximum values typically 0.02m and 0.10m respectively) and seston were fully mixed through the water column
Circular construction and demolition waste?: Barriers and opportunities for creating circular business models in the EU C&DW sector
No full textThe main goal of this paper is to identify barriers and opportunities for creating the circular business models in the EU C&DW sector. Having in mind this fact, author of the paper describes market, social, governance and regulatory failures which may limit opportunities for achieving market success in the EU C&DW sector. The presentation will take into account current economic situation of the sector which is under the pressure of both global economic challenges and the EU policy aiming at popularization of the circular economy approach. As a result, different recommendations that may determine the final shape of the business models will be identified, including key resources that have to be used for successful commercialization of the different circular C&DW solutions
Changes in Emiliania huxleyi fatty acid profiles during infection with E. huxleyi virus 86: physiological and ecological implications
No full textFatty acids profiles of Emiliania huxleyi strain CCMP1516 were determined in a virus-induced culture crash with E. huxleyi virus 86 (EhV-86). As cell numbers declined in the infected cultures due to virus lysis, a concomitant decrease in fatty acids was observed in the particulate fraction. The composition of fatty acids within infected E. huxleyi cells was restructured, with a shift from polyunsaturated to monounsaturated and saturated fatty acids (respective distributions changing from 70:10:20% at the start of the experiment to 44:24:32% at the final time point). In particular, decreases were seen in the major fatty acid 22:6(n-3) and in 18:5(n-3), whereas greatest increases were seen in 18:1(n-9) and 22:0. The increase in the amount and restructuring of the fatty acid pool in E. huxleyi was indicative of a combination of specific and non-specific effects of virus infection. Specific effects primarily included induction of metabolic pathways such as the synthesis of components involved in virus replication, the production of virions and signal transduction via sphingolipid biosynthesis. Non-specific effects due to stress were likely mediated by reactive oxygen species. Changes in the composition of virus-infected E. huxleyi are of significance to the food web since grazing on virus-infected blooms will decrease the amount of essential polyunsaturated fatty acids passed on to higher trophic levels. Consequently, this could decrease the overall productivity of marine ecosystems
Algae in fish feed: Performances and fatty acid metabolism in juvenile Atlantic Salmon
No full textAlgae are at the base of the aquatic food chain, producing the food resources that fish are adapted to consume. Previous studies have proven that the inclusion of small amounts (<10% of the diet) of algae in fish feed (aquafeed) resulted in positive effects in growth performance and feed utilisation efficiency. Marine algae have also been shown to possess functional activities, helping in the mediation of lipid metabolism, and therefore are increasingly studied in human and animal nutrition. The aim of this study was to assess the potentials of two commercially available algae derived products (dry algae meal), Verdemin (derived from Ulva ohnoi) and Rosamin (derived from diatom Entomoneis spp.) for their possible inclusion into diet of Atlantic Salmon (Salmo salar). Fish performances, feed efficiency, lipid metabolism and final product quality were assessed to investigated the potential of the two algae products (in isolation at two inclusion levels, 2.5% and 5%, or in combination), in experimental diets specifically formulated with low fish meal and fish oil content. The results indicate that inclusion of algae product Verdemin and Rosamin at level of 2.5 and 5.0% did not cause any major positive, nor negative, effect in Atlantic Salmon growth and feed efficiency. An increase in the omega-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA) content in whole body of fish fed 5% Rosamin was observed
An industry-scale mass marking technique for tracing farmed fish escapees
No full textFarmed fish escape and enter the environment with subsequent effects on wild populations. Reducing escapes requires the ability to trace individuals back to the point of escape, so that escape causes can be identified and technical standards improved. Here, we tested if stable isotope otolith fingerprint marks delivered during routine vaccination could be an accurate, feasible and cost effective marking method, suitable for industrial-scale application. We tested seven stable isotopes, 134Ba, 135Ba, 136Ba, 137Ba, 86Sr, 87Sr and 26Mg, on farmed Atlantic salmon reared in freshwater, in experimental conditions designed to reflect commercial practice. Marking was 100% successful with individual Ba isotopes at concentrations as low as 0.001 µg. g-1 fish and for Sr isotopes at 1 µg. g-1 fish. Our results suggest that 63 unique fingerprint marks can be made at low cost using Ba (0.0002 – 0.02 US per mark) isotopes. Stable isotope fingerprinting during vaccination is feasible for commercial application if applied at a company level within the world’s largest salmon producing nations. Introducing a mass marking scheme would enable tracing of escapees back to point of origin, which could drive greater compliance, better farm design and improved management practices to reduce escapes
First photometric study of two southern eclipsing binaries IS Tel and DW Aps
No full text32nd International Physics Congress of Turkish-Physical-Society (TPS) -- SEP 06-09, 2016 -- Bodrum, TURKEYThe paper presents the first photometric analysis of two southern eclipsing binary stars, IS Tel and DW Aps. Their V light curves from the All Sky Automated Survey were modelled by using Wilson-Devinney method. The final models give these two Algol-like binary stars as having detached configurations. Absolute parameters of the components of the systems were also estimated.Turkish Phys So
Bacteria in shrimp pond sediments: their role in mineralizing nutrients and some suggested sampling strategies
No full textStrategies for sampling sediment bacteria were examined in intensive shrimp, Penaeus monodon (Fabricius), ponds in tropical Australia. Stratified sampling of bacteria at the end of the production season showed that the pond centre, containing flocculated sludge, had significantly higher bacterial counts (15.5 X 10(9) g(-1) dw) than the pond periphery (8.1 X 10(9) g(-1) dw), where the action of aerators had swept the pond floor. The variation in bacterial counts between these two zones within a pond was higher than that between sites within each zone or between ponds. Therefore, sampling effort should be focused within these zones: for example, sampling two ponds at six locations within each of the two zones resulted in a coefficient of variation of approximate to 5%. Bacterial numbers in the sediment were highly correlated with sediment grain size, probably because eroded soil particles and organic waste both accumulated in the centre of the pond. Despite high inputs of organic matter added to the ponds, principally as pelleted feeds, the mean bacterial numbers and nutrient concentrations (i.e. organic carbon, nitrogen and phosphorus) in the sediment were similar to those found in mangrove sediments. This suggests that bacteria are rapidly remineralizing particulates into soluble compounds. Bacterial numbers were highly correlated with organic carbon and total kjeldahl nitrogen in the sediment, suggesting that these were limiting factors to bacterial growth
The role of microbes in the nutrition of detritivorous invertebrates: a stoichiometric analysis
No full textDetritus represents an important pool in the global carbon cycle, providing a food source for detritivorous invertebrates that are conspicuous components of almost all ecosystems. Our knowledge of how these organisms meet their nutritional demands on a diet that is typically comprised of refractory, carbon-rich compounds nevertheless remains incomplete. ‘Trophic upgrading’ of detritus by the attached microbial community (enhancement of zooplankton diet by the inclusion of heterotrophic protozoans) represents a potential source of nutrition for detritivores as both bacteria and their flagellated protistan predators are capable of biosynthesizing essential micronutrients such as polyunsaturated fatty acids (PUFAs). There is however a trade-off because although microbes enhance the substrate in terms of its micronutrient content, the quantity of organic carbon is diminished though metabolic losses as energy passes through the microbial food web. Here, we develop a simple stoichiometric model to examine this trade-off in the nutrition of detritivorous copepods inhabiting the mesopelagic zone of the ocean, focusing on their requirements for carbon and an essential PUFA, docosahexaenoic acid (DHA). Results indicate that feeding on microbes may be a highly favourable strategy for these invertebrates, although the potential for carbon to become limiting when consuming a microbial diet exists because of the inefficiencies of trophic transfer within the microbial food web. Our study highlights the need for improved knowledge at the detritus-microbe-metazoan interface, including interactions between the physiology and ecology of the associated organisms
Policy analysis of water management for the Netherlands. Vol VII: Assessment of impacts on drinking-water companies and their customers
No full textThis volume assesses the impacts of a number of water management policies developed by PAWN on drinking-water (DW) companies and their customers (households, commercial entities, and industrial firms). Chapter 2 summarizes briefly the major water-related problems facing DW companies in the Netherlands today, and shows why the author believes they will become more severe in the future. Chapter 3 describes the methodology in detail. Chapter 4 presents the impacts and associated discussion of PAWN's primary and groundwater cases on DW production, and on DW companies and their customers. Finally, in Chap. 5, the author assesses those impacts, draws some overall conclusions, and discusses the implications of those conclusions for the future supply and costs of DW in the Netherlands.PAW
Amara (Celia) aberrans BAUDI DI SELVE 1864
No full textAmara (Celia) aberrans BAUDI DI SELVE 1864 I s r a e l: Central District: SW Khadera (brackish pond), 27.III.2008, Wrase leg. [35] (1 spcm., cWR, Hieke det. 2008). A species, described from Cyprus, with several synonyms and rare in collections. Furthermore, it is known from the Balkan Peninsula (Greece, Macedonia), Libya, Turkey, Israel, Lebanon, Syria, and Iran (CATPAL 1: HIEKE 2003: 555). CHIKATUNOV et al. (2006: 294) listed it for Israel, based on material collected in light traps but without mentioning a locality. First detailed record for Israel.Published as part of Wrase, DW, 2009, New or interesting records of Carabid beetles from Europe, Madeira, northern Africa, Turkey, from the Near East, Iran, Iraq, Kuwait, and Pakistan, with nomenclatorial and taxonomic notes (Coleoptera, Carabidae, Bembidiini, Brachinini, Cyclosomini, Elaphrini, Harpalini, Lebiini, Nebriini, Platynini,, pp. 901-935 in Linzer biologische Beiträge 41 (1) on page 930, DOI: 10.5281/zenodo.527633
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