Ferskvandssymposiet 2010 - Ferskvandssymposiet 2012

Posters tema 4 – Klimaeffekter på ferske vande
Tema 4 – Klimaeffekter på ferske vande
4.1 Salinity tolerance of genetically different clones of Phragmites australis.
Luciana Achenbach og Hans Brix
Department of Plant Biology, Biologisk Institut, Aarhus University, Ole Worms Alle 1, 8000, Århus C
The understanding of salt tolerance mechanisms in non-halophytes is extremely important in
relation to the current climate change scenarios, which assume reduced surface water
supplies, low quality groundwater and sea level increase. All these aspects suggest that soil
salinity will naturally increases at high rates.
The aim of this study is to investigate the salt tolerance of 16 different Phragmites australis
clones, with different ploidy levels (4n, 6n, 8n, 10n, 12n) and different origins (Romania,
Russia, Japan, Czech Republic).
The clones were exposed to increasing salinity, from 8 ppt to 72 ppt. The effects of treatment
on growth, photosynthesis, transpiration, stomata conductance, as well as organ specific ion
accumulation were measured.
Salt stress strongly reduced plant-height, as well as chlorophyll and carotenoids content in all
clones. The physiological parameters significantly differed, the sensitive clones lowering their
photosynthesis, transpiration rate and stomata conductance already at concentrations of 16
ppt, while tolerant clones showed significant stress signs over 40 ppt.
Furthermore, the ion distribution in different plant organs was investigated on the surviving
plants harvested at the end of the experiment. It was revealed that the vacuoles of the old
leaves had been used by plants as deposits for salt specific ions (Na+, Cl-), while other parts
of the plant, like the roots, were not capable of storage, being damaged by this ion deposition.
All in all, Phragmites australis presents high tolerance towards salt stress, as well as significant
variability among the clones. These responses can be attributed to the genotypic structure and
the degree of phenotypic plasticity. Further investigation is required for a more complete
understanding of these tolerance mechanisms.
4.2 Klimaafledte faktorers betydning for reguleringen af ørredpopulationer -
Case studie af ørredpopulationen i Kalvemose Å.
Rune Olsen, Eva Bøgh og Martin Olsen
Roskilde Universitet, Institut for Miljø, Samfund og Rumlig Forandring (ENSPAC), 4000 Roskilde,
www.ecohydrology.ruc.dk, e-mail ruol@ruc.dk
Ørredpopulationers regulering påvirkes af en lang række af forskellige faktorer, som
overordnet kan inddeles i to undergrupper; densitetsafhængige faktorer og
densitetsuafhængige faktorer. Processerne bag de densitetsafhængige faktorer kan i princippet
være både positive og negative, hvilket vil sige at individets sandsynlighed for at overleve, kan
både falde og stige med densiteten. De densitetsuafhængige faktorer er derimod ikke
afhængige af bestandstætheden og kan påvirke mortaliteten i alle livsstadier og ved alle
tætheder. Vandløbets vandføring og temperatur er vigtige eksempler på dette, hvorfor også
klimaet er vigtigt, da variationer i disse faktorer et tæt knyttet til variationer i klimaet. På trods
af dette er antallet af undersøgelser omhandlende klimaafledte faktorers betydning for
reguleringen af ørredpopulationer begrænsede. Specielt studier over længere tidsperioder er
sjældne og en af de primære årsager hertil, er manglende ørreddata.
Formålet med dette projekt er at undersøge hvordan klimaafledte faktorer påvirker ørredernes
populationsudvikling over en længere periode. Kalvemose Å på Sjælland er valgt som case
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