Essays about: "food webs"

Showing result 31 - 35 of 37 essays containing the words food webs.

  1. 31. SOURCES OF DIOXINS TO BALTIC AIR Volatilization and Resuspension As Potential Secondary Sources of Dioxins to Air

    University essay from Kemiska institutionen

    Author : Van Anh Le; [2011]
    Keywords : ;

    Abstract : Persistent organic pollutants (POPs) are ubiquitous contaminants characterized by semi-volatility, low water solubility, high lipophilicity and inherent toxicity. A combination of these properties results in long-rang transport, bioaccumulation and biomagnification through food webs. READ MORE

  3. 32. Effects of food quantity, dietary fatty acids and temperature on fitness of Daphnia magna : a factorial experiment with Scenedesmus acutus and EPA amendments

    University essay from SLU/Dept. of Aquatic Sciences and Assessment

    Author : Bernadette Pree; [2011]
    Keywords : Daphnia magna; temperature; Scenedesmus acutus; food quality; dietary fatty acid amendment; food concentration; pelagic food web;

    Abstract : The performance of zooplankton has a major impact on the efficiency in trophic transfer in pelagic food webs and is therefore examined in this study. I investigated the effect of different food quantity and food quality, as measured by omega-3 fatty acid (ω3-FA) content on survival, somatic growth and reproduction of Daphnia magna at high and low temperatures in laboratory growth experiments. READ MORE

  4. 33. Multiple pesticide stressors and ecosystem functioning in stream detrital food webs

    University essay from SLU/Dept. of Aquatic Sciences and Assessment

    Author : Mohab Dawoud; [2011]
    Keywords : Stream ecosystem; decomposition process; leaf litter; Lindane; Azoxystrobin; Asellus aquaticus; aquatic microorganism;

    Abstract : Streams and rivers are highly susceptible to environmental degradation from agricultural activities, including the clearance of riparian vegetation and the runoff of chemical fertilizers and pesticides. These impacts are likely to increase in the future as agricultural practices intensify to meet the needs of an expanding human population. READ MORE

  5. 34. Ecologically viable population sizes: Determining factors

    University essay from Institutionen för fysik, kemi och biologi

    Author : Stefan Sellman; [2010]
    Keywords : assembly model; ecologically effective populations; extinction; keystone species; MEVP; MVP; species interactions;

    Abstract : The minimum ecologically viable population size (MEVP) of a species describes the minimum size at which the species itself or another species in the same ecosystem goes extinct as a result of the loss of inter-specific interactions. The MEVP shows a good potential for use as a tool for exploring the mechanisms behind species extinctions, but presently only a small amount of research has been done that takes advantage of this. READ MORE

  6. 35. Stabilizing factors in spatially structured food webs

    University essay from Teoretisk Biologi; Ekologi

    Author : Sara Gudmundson; [2009]
    Keywords : Dispersal; extinction risk; food web; metapopulation; noise; spatial distribution; stability; synchrony.;

    Abstract : Ecological models have problems showing the positive relationship between diversity and stability found in nature. Theory states that complex food webs have high extinction risks and low stability. However, persistent food webs found in nature are large and complex containing many interconnections between species. READ MORE