Tobias Vrede

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TOBIAS VREDE*, ASHLEY BALLANTYNE, CECILIA MILLE-LINDBLOM*, GRETE ALGESTEN*, CRISTIAN GUDASZ , SANDRA LINDAHL* AND ANNA KRISTINA BRUNBERG* *Department of Ecology and Evolution ⁄Limnology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, U.S.A. Department(More)
Phototrophic primary production is a fundamental ecosystem process, and it is ultimately constrained by access to limiting nutrients. Whereas most research on nutrient limitation of lacustrine phytoplankton has focused on phosphorus (P) and nitrogen (N) limitation, there is growing evidence that iron (Fe) limitation may be more common than previously(More)
Blooms of the nontoxic raphidophyte Gonyostomum semen have shown a recent increase in frequency and distribution in the Fennoscandian region. Due to large cell size and several grazer-avoidance strategies, G. semen is hypothesized to be inedible for most zooplankton species and therefore may constitute a bottleneck for the transfer of energy and nutrients(More)
The effect of temperature and viscosity on the ingestion rate of Daphnia galeata and Chydorus sphaericus was investigated in short-term feeding experiments with 3H-labelled Scenedesmus quadricauda. Viscosity was manipulated independently from temperature by addition of inert polymers in two experiments. In the first experiment, the ingestion rate of D.(More)
The large bloom-forming flagellate Gonyostomum semen has been hypothesized to be inedible to naturally occurring zooplankton due to its large cell size and ejection of long slimy threads (trichocysts) induced by physical stimulation. In a grazing experiment using radiolabelled algae and zooplankton collected from lakes with recurring blooms of G. semen and(More)
Most Scandinavian rivers are impounded for power production. High altitude reservoirs retain water during summer and fall for power production during winter and spring. The oligotrophic lakes Mjölkvattnet and Burvattnet were impounded in 1942. Annual water level fluctuations caused by regulation have resulted in a loss of littoral habitat, and Arctic char(More)
Several species in the genus Arnica have been used in traditional medicine to treat inflammatory-related disorders. Extracts of twelve Arnica species and two species closely related to arnica ( Layia hieracioides and Madia sativa) were investigated for inhibition of human neutrophil elastase release and inhibition of transcription factor NF-kappaB.(More)
Dystrophic lakes are widespread in temperate regions and intimately interact with surrounding terrestrial ecosystems in energy and nutrient dynamics, yet the relative importance of autochthonous and allochthonous resources to consumer production in dystrophic lakes remains controversial. We argue that allochthonous organic matter quantitatively dominates(More)
This study demonstrates that clear and humic freshwater pelagic communities respond differently to the same environmental stressors, i.e. nutrient and light availability. Thus, effects on humic communities cannot be generalized from existing knowledge about these environmental stressors on clear water communities. Small humic lakes are the most numerous(More)
Nutrient limitation of primary producers and their consumers can have a large influence on ecosystem productivity. The nature and strength of nutrient limitation is driven both by external factors (e.g., nutrient loading) and internal processes (e.g., consumer-driven nutrient regeneration). Here we present results from a field study in 10 low productive(More)