Auflistung nach Autor:in "Velle, Gaute"

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Biodiversity of macro-invertebrates in acid-sensitive waters: trends and relations to water chemistry and climate
(Norsk Institutt for Vannforskning , 2016) Velle, Gaute; Arle, Jens; Mahlum, Shad; Monteith, Don T.
This is a study of the international impact of acid emission reductions on vulnerable freshwater biodiversity of benthic macroinvertebrates. In order to properly attribute impacts it is necessary to also incorporate the potential effects of changes in temperature and precipitation. Most sites show an increasing number of species towards the present. This can be attributed to a decrease in acidification, while temperature has a secondary influence on diversity. We expect that the biodiversity will continue to increase in the future as acid deposition decreases. The widespread response of aquatic diversity resulting from emission reductions of acidifying components to the atmosphere demonstrates the potential of international policy for achieving positive effects on the state of the environment. Quelle: https://brage.bibsys.no
Trends and drivers of biodiversity of benthic invertebrates in European freshwaters
(2016) Velle, Gaute; Chipperfield, Joseph; Arle, Jens; Eriksson, Lars; Fölster, Jens; Indriksone, Iveta; Mahlum, Shad; Monteith, Don T.; Shilland, Ewan; Stuchlik, Evzen; Telford, Richard; Wit, Heleen de
This study includes analyses of trends and drivers of species diversity of benthic invertebrates in European rivers and lakes. The invertebrates were sampled at freshwater monitoring sites in the Czech Republic, Germany, Latvia, Norway, Sweden and the UK. The data includes about 1.8 million benthic macroinvertebrates from 5225 samples in 55 rivers and 34 lakes collected between 1982 and 2014. In addition, data on water chemistry, precipitation and temperature from the same sites and periods are included, where such data exist. The study sites forms part of national monitoring programmes and most represent sites of nutrient poor waters that have been influenced by long-range air pollution leading to acidification and are now in a process of chemical recovery. To our knowledge, no comparable studies on biodiversity exist at this scale.
Over the monitoring period, the concentration of sulphate has decreased, while pH and buffering capacity (ANC) have increased. A majority of the rivers and lakes (70 of 89 sites) show a net increase in species diversity (both richness and Shannon), albeit the increase is not statistically significant for all sites. The biodiversity of lakes has increased to a smaller extent than the biodiversity of rivers.
The biodiversity increase is correlated with sulphate (SO4), pH and monthly minimum temperature. There is no lag between SO4 or pH and a change in biodiversity. For temperature, a lag around one year provides the best fit, suggesting that the temperature now may influence the biodiversity next year. Pressure from acidification also influenced the stability of the biological community in rivers, with greater short-term variation in the invertebrate community during times of higher SO4. Likewise, the stability of the biological community of lakes could be linked to variation in mean monthly precipitation with greater short-term variation during times of low precipitation.
A Bayesian model predicts that if European water quality and environment stabilises, then a continued increase in biodiversity across nearly all sites is expected. However, the increase will be counteracted by any further regional increase in temperature.In: Book of Abstracts : 33rdSIL Congress, July 31, 2016 - August 5, 2016, Torino, Italy/ International Society of Limnology, S. 67