Sökning: "daphnia"

Visar resultat 1 - 5 av 48 avhandlingar innehållade ordet daphnia.

1. 1. Understanding hazards of nanoplastics using Daphnia magna

   Författare :Egle Kelpsiene; NanoLund: Centre for Nanoscience; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Daphnia magna; nanoplastics; polystyrene; polylactic acid nanoparticles;

   Sammanfattning : This thesis presents the results of studies focused on effects caused by nano-sized particles using freshwater filter feeder Daphnia magna. I showed that both positively and negatively surface charged PS NPs induced significant mortality in D. magna after a life-time (103 days) of exposure at low concentrations. LÄS MER

3. 2. Food Quality Effects on Zooplankton Growth and Energy Transfer in Pelagic Freshwater Food Webs

   Författare :Jonas Persson; Tobias Vrede; Peter Eklöv; Ellen van Donk; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; elemental stoichiometry; phosphorus; polyunsaturated fatty acids; EPA; oligotrophic lakes; empirical modelling; Daphnia; Cladocera; Copepoda; Ekologi;

   Sammanfattning : Poor food quality can have large negative effects on zooplankton growth and this can also affect food web interactions. The main aims of this thesis were to study the importance of different food quality aspects in Daphnia, to identify potentially important differences among zooplankton taxa, and to put food quality research into a natural context by identifying the importance of food quality and quantity in lakes of different nutrient content. LÄS MER

4. 3. Effects of warming and nutrient enrichment on feeding behavior, population stability and persistence of consumers and their resources

   Författare :Wojciech Uszko; Sebastian Diehl; Lennart Persson; David Vasseur; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; consumer-resource; Daphnia; functional response; nutrient enrichment; parameter estimation; persistence; plankton; predator-prey; stability; temperature; type II; type III; warming;

   Sammanfattning : Consumer-resource interactions are the basic building blocks of every food web. In spite of being a central research theme of longstanding interest in ecology, the mechanisms governing the stability and persistence of consumer-resource interactions are still not entirely understood. LÄS MER

5. 4. Daphnids adaptive strategies to UV radiation

   Författare :Carla Eloisa Fernández; Avdelningen för Teknisk vattenresurslära; []
   Nyckelord :Cladocera; Zooplankton; Andean lakes; Daphnia; Ultraviolet radiation; Migration strategy; Photo-protection;

   Sammanfattning : This thesis focuses on the adaptive strategies of daphnids that allows them to maintain stable populations while deal with UV radiation, highlighting the differences in the responses that populations with different evolutionary histories may have.Although exposition to lethal doses in nature is unlikely, sub-lethal UV-B radiation doses may have strong impacts on zooplankton. LÄS MER

7. 5. Psychotropic Pharmaceuticals in Aquatic Systems: An Ecological Perspective

   Författare :Melanie Hedgespeth; Enhet akvatisk ekologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ecotoxicology; aquatic; trophic level; pharmaceutical; SSRI; beta-blocker; sertraline; fluoxetine; propranolol; fish; daphnia; snail; predator; prey; behavior; life history; multiple stressor;

   Sammanfattning : Psychotropic pharmaceuticals have been shown to exert a variety of sublethal effects on non-target organisms, even at low concentrations found in the environment (ng/L to µg/L); hence, the aim of my research has been to determine the individual-level effects of psychotropic pharmaceuticals (the selective serotonin reuptake inhibitors sertraline and fluoxetine, and the β-blocker propranolol) on behavioral and life history traits in freshwater organisms. Further, this research was directed towards assessing the potential large-scale impacts of these effects on population growth and predator-prey interactions (with community-level implications) via the application of traditional, ecological concepts and models. LÄS MER