Birger Skjelbred
Norwegian Institute for Water Research
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Publication
Featured researches published by Birger Skjelbred.
Journal of Applied Ecology | 2013
Laurence Carvalho; Claire McDonald; Caridad de Hoyos; Ute Mischke; Geoff Phillips; Gábor Borics; Sandra Poikane; Birger Skjelbred; Anne Lyche Solheim; Jeroen Van Wichelen; Ana Cristina Cardoso
1. A safe, clean water supply is critical for sustaining many important ecosystem services provided by freshwaters. The development of cyanobacterial blooms in lakes and reservoirs has a major impact on the provision of these services, particularly limiting their use for recreation and water supply for drinking and spray irrigation. Nutrient enrichment is thought to be the most important pressure responsible for the widespread increase in cyanobacterial blooms in recent decades. Quantifying how nutrients limit cyanobacterial abundance in lakes is, therefore, a key need for setting robust targets for the management of freshwaters. 2. Using a dataset from over 800 European lakes, we highlight the use of quantile regression modelling for understanding the maximum potential capacity of cyanobacteria in relation to total phosphorus (TP) and the use of a range of quantile responses, alongside World Health Organisation (WHO) health alert thresholds for recreational waters, for setting robust phosphorus targets for lake management in relation to water use. 3. The analysis shows that cyanobacteria exhibit a non-linear response to phosphorus with the sharpest increase in cyanobacterial abundance occurring in the TP range from about 20 µg L-1 up to about 100 µg L-1. 4. The likelihood of exceeding the World Health Organisation (WHO) ‘low health alert’ threshold increases from about 5% exceedance at 16 µg L-1 to 40% exceedance at 54 µg L-1. About 50% of the studied lakes remain below this WHO health alert threshold, irrespective of high summer TP concentrations, highlighting the importance of other factors affecting cyanobacteria population growth and loss processes, such as high flushing rate. 5. Synthesis and applications. Developing a more quantitative understanding of the effect of nutrients on cyanobacterial abundance in freshwater lakes provides important knowledge for restoring and sustaining a safe, clean water supply for multiple uses. Our models can be used to set nutrient targets to sustain recreational services and provide different levels of precaution that can be chosen dependent on the importance of the service provision.
Hydrobiologia | 2013
Laurence Carvalho; Sandra Poikane; A. Lyche Solheim; Geoff Phillips; Gábor Borics; Jordi Catalan; C. De Hoyos; Stina Drakare; Bernard Dudley; Marko Järvinen; Christophe Laplace-Treyture; Kairi Maileht; Claire McDonald; Ute Mischke; Jannicke Moe; Giuseppe Morabito; Peeter Nõges; Tiina Nõges; Ingmar Ott; Agnieszka Pasztaleniec; Birger Skjelbred; Stephen J. Thackeray
Phytoplankton constitutes a diverse array of short-lived organisms which derive their nutrients from the water column of lakes. These features make this community the most direct and earliest indicator of the impacts of changing nutrient conditions on lake ecosystems. It also makes them particularly suitable for measuring the success of restoration measures following reductions in nutrient loads. This paper integrates a large volume of work on a number of measures, or metrics, developed for using phytoplankton to assess the ecological status of European lakes, as required for the Water Framework Directive. It assesses the indicator strength of these metrics, specifically in relation to representing the impacts of eutrophication. It also examines how these measures vary naturally at different locations within a lake, as well as between lakes, and how much variability is associated with different replicate samples, different months within a year and between years. On the basis of this analysis, three of the strongest metrics (chlorophyll-a, phytoplankton trophic index (PTI), and cyanobacterial biovolume) are recommended for use as robust measures for assessing the ecological quality of lakes in relation to nutrient-enrichment pressures and a minimum recommended sampling frequency is provided for these three metrics.
Hydrobiologia | 2013
Geoff Phillips; Anne Lyche-Solheim; Birger Skjelbred; Ute Mischke; Stina Drakare; Gary Free; Marko Järvinen; Caridad de Hoyos; Giuseppe Morabito; Sandra Poikane; Laurence Carvalho
Despite improvements in wastewater treatment systems, the impact of anthropogenic nutrient sources remains a key issue for the management of European lakes. The Water Framework Directive (WFD) provides a mechanism through which progress can be made on this issue. The Directive requires a classification of the ecological status of phytoplankton, which includes an assessment of taxonomic composition. In this paper, we present a composition metric, the plankton trophic index, that was developed in the WISER EU FP7 project and demonstrate how it has been used to compare national phytoplankton classification systems in Northern and Central Europe. The metric was derived from summer phytoplankton data summarised by genus from 1,795 lakes, covering 20 European countries. We show that it is significantly related to total phosphorus concentrations, but that it is also sensitive to alkalinity, lake size and climatic variables. Through the use of country-specific reference values for the index, we demonstrate that it is significantly related to other national phytoplankton assessment systems and illustrate for a single European (intercalibration) lake type how it was used to intercalibrate WFD boundaries from different countries.
Hydrobiologia | 2013
Marko Järvinen; Stina Drakare; Gary Free; Anne Lyche-Solheim; Geoff Phillips; Birger Skjelbred; Ute Mischke; Ingmar Ott; Sandra Poikane; Martin Søndergaard; Agnieszka Pasztaleniec; Jeroen Van Wichelen; Robert Portielje
Phytoplankton data from 606 lakes were used to characterize indicator taxa of near-pristine reference conditions in clearwater and humic lowland lakes of Northern and Central Europe. Reference lakes were selected based on low pressure from catchment land-use, low population density and the absence of point sources. Reference lakes had low phytoplankton biomass and taxa richness compared to non-reference lakes. In low alkalinity lakes of Northern Europe, the reference communities had high biomass proportions of chrysophytes and low proportions of cyanobacteria; in the Central European high alkalinity lakes, the biomass was distributed more evenly among algal groups. Indicator species analysis and similarity analysis listed 5–29 taxa indicating reference conditions. Indicator taxa differed especially between the low alkalinity and the high alkalinity lakes, but there were also country-specific differences. Most common indicator taxa for the northern reference lakes were chrysophytes (e.g. Bitrichia, Dinobryon). In the Central European reference lakes, diatoms (e.g. Cyclotella) were more characteristic. Despite the differences, there was a general finding that taxa present in reference lakes were often also present in non-reference lakes, but typically in lower biomass proportions; another characteristic of the reference communities is the absence of many taxa typically found in non-reference lakes.
Hydrobiologia | 2015
Camilla H. C. Hagman; Andreas Ballot; Dag Øystein Hjermann; Birger Skjelbred; Pål Brettum; Robert Ptacnik
The invasive and nuisance microalga Gonyostomum semen has recently expanded its geographical distribution and increased its biomass in Sweden and Finland. Temperatures, total organic carbon (TOC), water colour and phosphorous are main factors suggested as drivers for its success. Already in the 1980s there were indications of the same patterns also in Norway, and in this study we further examine these observations based on the hypotheses that (1) G. semen has continued its increase in abundance in Norway since then, (2) after settling in a lake, G. semen may increase its biomass, provided a simultaneous change in climatic factors. We use existing data from Norwegian monitoring databases for the study and additional water samples to investigate distribution. G. semen was detected by microscopy and quantitative PCR, while trends over time in G. semen biomass and possible explanatory variables were analysed by simple regression. We show that G. semen has increased its distribution in Norway since the 1980s, geographically and to new lakes. In eight of the nine lakes studied, the proportion of G. semen biomass in lake phytoplankton has increased with time. These changes seem to be explained only to some degree by temperature, TOC, water colour and phosphorous.
Journal of Phycology | 2013
Birger Skjelbred; Bente Edvardsen; Tom Andersen
The ichthyotoxic flagellate Pseudochattonella has formed recurrent blooms in the North Sea, Skagerrak and Kattegat since 1998. Five strains of Pseudochattonella farcimen and two strains of P. verruculosa were examined in an assay comparing the light response of specific growth rates over a range of temperatures and salinities to get further knowledge on the autecology of members of this genus. Temperature optima were lower in P. farcimen (9°C–15°C) than in P. verruculosa (12°C–20°C). P. farcimen also showed a somewhat lower salinity optimum (18–26) than P. verruculosa (20–32). All strains showed light‐dependent growth responses reaching saturation between 18 and 52 μmol · photons · m−2 · s−1 at optimal temperature and salinity conditions. Compensation point estimates ranged from 4.2 to 15 μmol · photons · m−2 · s−1. Loss rates increased with temperature and were lowest at salinities close to optimal growth conditions. Blooms of P. farcimen have been recorded in nature under conditions more similar to those minimizing loss rates rather than those maximizing growth rates in our culture study.
Harmful Algae | 2011
Birger Skjelbred; Tor Einar Horsberg; Knut Erik Tollefsen; Tom Andersen; Bente Edvardsen
Ecological Indicators | 2013
Stephen J. Thackeray; Peeter Nõges; Michael J. Dunbar; Bernard Dudley; Birger Skjelbred; Giuseppe Morabito; Laurence Carvalho; Geoff Phillips; Ute Mischke; Jordi Catalan; Caridad de Hoyos; Christophe Laplace; Martina Austoni; Bachisio Mario Padedda; Kairi Maileht; Agnieszka Pasztaleniec; Marko Järvinen; Anne Lyche Solheim; R. T. Clarke
Journal of Applied Phycology | 2012
Birger Skjelbred; Bente Edvardsen; Tom Andersen
Archive | 2012
Ute Mischke; Stephen J. Thackeray; Michael J. Dunbar; Claire McDonald; Laurence Carvalho; Caridad de Hoyos; Marko Järvinen; Christophe Laplace-Treyture; Giuseppe Morabito; Birger Skjelbred; Anne Lyche Solheim; Bill Brierley; Bernard Dudley