| 1. |
- Bergkvist, Johanna, 1980, et al.
(författare)
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Grazer-induced chain length plasticity reduces grazing risk in a marine diatom
- 2012
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590. ; 57:1, s. 318-324
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Tidskriftsartikel (refereegranskat)abstract
- We show that Skeletonema marinoi suppresses chain formation in response to copepod cues. The presence of three different copepod species (Acartia tonsa, Centropages hamatus, or Temora longicornis) significantly reduced chain length. Furthermore, chain length was significantly reduced when S. marinoi was exposed to chemical cues from caged A. tonsa without physical contact with the responding cells. The reductions in chain length significantly reduced copepod grazing; grazing rates on chains (four cells or more) were several times higher compared to that of single cells. This suggests that chain length plasticity is a means for S. marinoi to reduce copepod grazing. In contrast, chain length was not suppressed in cultures exposed to the microzooplankton grazer Gyrodinium dominans. Size-selective predation may have played a key role in the evolution of chain formation and chain length plasticity in diatoms.
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| 2. |
- Drotz, Marcus, 1968, et al.
(författare)
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Forskning och kunskapsproducenter runt Vänern. Kunskapsunderlag inom Vänersamarbetet
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten är en kunskaps- och forskningsinventering av befintlig och avslutad forskning, samt kunskapsproducenter med anknytning till Vänern. Geografiskt har inventeringen begränsats till kommunerna i anslutning till Vänern samt vattnet och dess tillflöden, utflöde och kanaler. Ämnesmässigt har inventeringen fokuserat på forskning och kunskapsproduktion som direkt rör Vänerområdet inom såväl natruvetenskap, samhällsvetenskap som humaniora, speciellt det som rör arbetet inom Vänersamarbetet som är relaterat till hållbar utveckling socialt, ekonomiskt och ekologiskt. Tidsmässigt har arbetet fokuserats på att sammanställa projekt som pågår eller är avslutade under de senaste fem åren. Genom denna avgränsning har vi i mindre utsträckning tagit med forskning, kunskapsproduktion, nätverk och myndighetsdokumentation som rör större regionala områden eller Sverige i stort. Målgruppen är forskare, tjänstemän och beslutsfattare inom den offentliga sektorn. Projektet har genomförts i samarbete med Västra Götalandsregionen och Region Värmland. Till rapporten hör en referenssamling i form av en bilaga, ISBN: 91-88048-18-7.
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| 3. |
- Drotz, M.K., et al.
(författare)
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Lake Vänern: A historical outline
- 2014
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Ingår i: Aquatic Ecosystem Health and Management. - : Michigan State University Press. - 1463-4988 .- 1539-4077. ; 17:4, s. 323-330
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Tidskriftsartikel (refereegranskat)abstract
- © 2014, Copyright © AEHMS. Although Lake Vänern is the largest freshwater reservoir in Western Europe, it remains relatively unknown to the scientific community outside of Scandinavia. Therefore, we aim to give a brief outline of the lake and its geological history, in particular the landscape transformation, resource utilization, pollution history, and environmental development of the region. The landscape around Lake Vänern was shaped into its present form during the latest glaciations some 10,000years ago. Large variation exists in its tributaries, with forest in the north and agricultural areas in the south. Human influence on the landscape was relatively small until the mid-18th century. Later, in the mid-19th century, the agriculture, forestry and shipping industries underwent large transformations as the towns around the lake grew and the economy changed. Development of fishing equipment, processes and changes in catching methods industrialized the fishing industry after mid-20th century. In the 1960s the lake was considered to be one of the most heavily mercury-polluted lakes in the world. After the passing of the first national environmental protection law in Sweden the lake turned into a success story: It has been declared to be healthy. However, old pollution still affects the fishing industry. With this new focus on the environment, the scientific community started to be interested in the lake. The lake has also played a very important role as the largest hydropower reservoir in Sweden. Here, too, the environmental question is in focus and the effects of the water regulation are still under debate. The result has been loss of biodiversity and an increased risk of an inflow of invasive species from international shipping. However, still many questions remain to be answered regarding the lake and effect of ongoing climate change on the sustainable development of the lake region.
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| 4. |
- Hoffmann, L. J., et al.
(författare)
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Influence of trace metal release from volcanic ash on growth of Thalassiosira pseudonana and Emiliania huxleyi
- 2012
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 132-133, s. 28-33
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies demonstrate that volcanic ash has the potential to increase phytoplankton biomass in the open ocean. However, besides fertilizing trace metals such as Fe, volcanic ash contains a variety of potentially toxic metals such as Cd, Cu, Pb, and Zn. Especially in coastal regions closer to the volcanic eruption, where ash depositions can be very high, toxic effects are possible. Here we present the first results from laboratory experiments, showing that trace metal release from different volcanic ashes can have both fertilizing and toxic effects on marine phytoplankton in natural coastal seawater. The diatom Thalassiosira pseudonana generally showed higher growth rates in seawater that was in short contact with volcanic ash compared to the controls without ash addition. In contrast to that, the addition of volcanic ash had either no effect or significantly decreased the growth rate of the coccolithophoride Emiliania huxleyi. It was not possible to attribute the effects to single trace metals, however, our results suggest that Mn plays an important role in regulating the antagonistic and synergistic effects of the different trace metals. This study shows that volcanic ash can lead to changes in the phytoplankton species composition in the high fall-out area of the surface ocean.
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| 5. |
- Munawar, M., et al.
(författare)
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Preface
- 2014
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Ingår i: Aquatic Ecosystem Health and Management. - : Michigan State University Press. - 1463-4988 .- 1539-4077. ; 17:4, s. 321-322
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Paul, C., et al.
(författare)
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Diatom Derived Polyunsaturated Aldehydes Do Not Structure the Planktonic Microbial Community in a Mesocosm Study
- 2012
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Ingår i: Marine Drugs. - Basel : MDPI AG. - 1660-3397. ; 10:4, s. 775-792
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Tidskriftsartikel (refereegranskat)abstract
- Several marine and freshwater diatoms produce polyunsaturated aldehydes (PUA) in wound-activated processes. These metabolites are also released by intact diatom cells during algal blooms. Due to their activity in laboratory experiments, PUA are considered as potential mediators of diatom-bacteria interactions. Here, we tested the hypothesis that PUA mediate such processes in a close-to-field mesocosm experiment. Natural plankton communities enriched with Skeletonema marinoi strains that differ in their PUA production, a plankton control, and a plankton control supplemented with PUA at natural and elevated concentrations were observed. We monitored bacterial and viral abundance as well as bacterial community composition and did not observe any influence of PUA on these parameters even at elevated concentrations. We rather detected an alternation of the bacterial diversity over time and differences between the two S. marinoi strains, indicating unique dynamic bacterial communities in these algal blooms. These results suggest that factors other than PUA are of significance for interactions between diatoms and bacteria.
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