The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the... more The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner.
Shallow lakes are globally the most numerous water bodies and are sensitive to external perturbat... more Shallow lakes are globally the most numerous water bodies and are sensitive to external perturbations, including eutrophication and climate change, which threaten their functioning. Extreme events, such as heat waves (HWs), are expected to become more frequent with global warming. To elucidate the effects of nutrients, warming, and HWs on zooplankton community structure, we conducted an experiment in 24 flow-through mesocosms (1.9 m in diameter, 1.0 m deep) imitating shallow lakes. The mesocosms have two nutrient levels (high (HN) and low (LN)) crossed with three temperature scenarios based on the Intergovernmental Panel on Climate Change (IPCC) projections of likely warming scenarios (unheated, A2, and A2 + 50%). The mesocosms had been running continuously with these treatments for 11 years prior to the HW simulation, which consisted of an additional 5 °C increase in temperature applied from 1 July to 1 August 2014. The results showed that nutrient effects on the zooplankton commun...
In the EU Water Framework Directive, lakes are classified into different types primarily on the b... more In the EU Water Framework Directive, lakes are classified into different types primarily on the basis of morphological and chemical characteristics. Lake type definition is not trivial because the different lake types may require different nutrient loading reduction targets to achieve the goal of at least "good" ecological status. Using data from 770 Danish lakes, we illustrate some of the problems associated with classification. In Denmark, 16 potentially different lake types are defined using an alkalinity boundary of 0.2 meq/L, a colour boundary of 60 mg/L Pt, a salinity boundary of 0.5‰, and a water mean depth boundary of 3 m. However, all classification variables showed considerable seasonal and interannual variation. Most lakes with a mean depth <3 m were polymictic, but stratification depended on lake size, complicating simple classification according to depth. Conditional inference tree analyses defined relatively clearly delineated groups of macrophytes, phytoplankton, and fish based on species presence, thereby confirming the relevance of using lake type classification. Alkalinity and salinity were the 2 most important factors and defined alkalinity split points at 0.07 and 0.76 meq/L and salinity split points between 0.5‰ and 4‰. However, with a few exceptions, the individual taxa occurred over a broad range of lake characteristics. Lake classification may be necessary for management reasons, but the absence of well-defined boundaries among lake types and a large natural variability in morphological and chemical characteristics urge cautious decisions when defining targets for external nutrient loading reduction for the various lake categories.
Lake Säkylän Pyhäjärvi has been an important fishing site and drinking water source for the local... more Lake Säkylän Pyhäjärvi has been an important fishing site and drinking water source for the local population for centuries. The lake has undergone significant changes: (1) the water level was lowered in the 1600s and in the 1850s; (2) planktivorous coregonid fish were successfully introduced in the early 1900s; (3) nutrient input from intensified agriculture has increased since the 1950s and (4) the effects of the current variable climate on the lake and its catchment have become more evident since the 1990s. We determined the phases of oligotrophication, eutrophication and recovery and elucidated the ecosystem changes by combining palaeolimnological records with detailed neolimnological data. The sedimentary diatom and cladoceran assemblages first showed a relatively eutrophic period followed by oligotrophic periods, linked with the artificial changes in water level and consequent shifts in macrophyte abundance. The oligotrophic period in the early 1900s is thought to represent the target trophic state for the lake. After the 1950s, introduction of vendace resulted in higher planktivory reflected by an increased relative abundance of small-bodied pelagic cladocerans. Signs of eutrophication occurred due to increased nutrient load. During the last 10 years, signs of recovery have been recorded. A complex history such as that of Lake Pyhäjärvi illustrates the difficulties in selecting management targets, and the risk of setting false targets, for lakes based solely on monitoring data-both neolimnological and palaeolimnological approach are needed.
... Også en stor tak til søgruppens øvrige AC&amp;#x27;ere, nu og gennem ti-den, for en stor ... more ... Også en stor tak til søgruppens øvrige AC&amp;#x27;ere, nu og gennem ti-den, for en stor indsats og de fælles bestræbelser på at få det hele til at gå op i en højere enhed på alle felter: Jens Peder Jensen, Torben Lauridsen, Su-sanne Lildal Amsinck, Rikke Bjerring Hansen, Asger Roer ...
Due date of deliverable: Month 12 Actual submission date: Month 12 Project co-funded by the Europ... more Due date of deliverable: Month 12 Actual submission date: Month 12 Project co-funded by the European Commission within the Seventh Framework Programme (2007-2013) Dissemination Level PU Public X PP Restricted to other programme participants (including the Commission Services) RE Restricted to a group specified by the consortium (including the Commission Services) CO Confidential, only for members of the consortium (including the Commission Services) Guidelines for indicator development Document history (and future) Version 1 produced by Daniel Hering and Sebastian Birk (UDE) by 15/12/09. Commented by the members of the WISER Steering Group by 4/1/10. Version 2 produced by UDE based on these comments. Commented by the relevant workpackage leaders and workpackage scientists (WP3.1 to 4.4) (by 31/1/10
Phytoplankton data from 606 lakes were used to characterize indicator taxa of near-pristine refer... more 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
The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the... more The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner.
Shallow lakes are globally the most numerous water bodies and are sensitive to external perturbat... more Shallow lakes are globally the most numerous water bodies and are sensitive to external perturbations, including eutrophication and climate change, which threaten their functioning. Extreme events, such as heat waves (HWs), are expected to become more frequent with global warming. To elucidate the effects of nutrients, warming, and HWs on zooplankton community structure, we conducted an experiment in 24 flow-through mesocosms (1.9 m in diameter, 1.0 m deep) imitating shallow lakes. The mesocosms have two nutrient levels (high (HN) and low (LN)) crossed with three temperature scenarios based on the Intergovernmental Panel on Climate Change (IPCC) projections of likely warming scenarios (unheated, A2, and A2 + 50%). The mesocosms had been running continuously with these treatments for 11 years prior to the HW simulation, which consisted of an additional 5 °C increase in temperature applied from 1 July to 1 August 2014. The results showed that nutrient effects on the zooplankton commun...
In the EU Water Framework Directive, lakes are classified into different types primarily on the b... more In the EU Water Framework Directive, lakes are classified into different types primarily on the basis of morphological and chemical characteristics. Lake type definition is not trivial because the different lake types may require different nutrient loading reduction targets to achieve the goal of at least "good" ecological status. Using data from 770 Danish lakes, we illustrate some of the problems associated with classification. In Denmark, 16 potentially different lake types are defined using an alkalinity boundary of 0.2 meq/L, a colour boundary of 60 mg/L Pt, a salinity boundary of 0.5‰, and a water mean depth boundary of 3 m. However, all classification variables showed considerable seasonal and interannual variation. Most lakes with a mean depth <3 m were polymictic, but stratification depended on lake size, complicating simple classification according to depth. Conditional inference tree analyses defined relatively clearly delineated groups of macrophytes, phytoplankton, and fish based on species presence, thereby confirming the relevance of using lake type classification. Alkalinity and salinity were the 2 most important factors and defined alkalinity split points at 0.07 and 0.76 meq/L and salinity split points between 0.5‰ and 4‰. However, with a few exceptions, the individual taxa occurred over a broad range of lake characteristics. Lake classification may be necessary for management reasons, but the absence of well-defined boundaries among lake types and a large natural variability in morphological and chemical characteristics urge cautious decisions when defining targets for external nutrient loading reduction for the various lake categories.
Lake Säkylän Pyhäjärvi has been an important fishing site and drinking water source for the local... more Lake Säkylän Pyhäjärvi has been an important fishing site and drinking water source for the local population for centuries. The lake has undergone significant changes: (1) the water level was lowered in the 1600s and in the 1850s; (2) planktivorous coregonid fish were successfully introduced in the early 1900s; (3) nutrient input from intensified agriculture has increased since the 1950s and (4) the effects of the current variable climate on the lake and its catchment have become more evident since the 1990s. We determined the phases of oligotrophication, eutrophication and recovery and elucidated the ecosystem changes by combining palaeolimnological records with detailed neolimnological data. The sedimentary diatom and cladoceran assemblages first showed a relatively eutrophic period followed by oligotrophic periods, linked with the artificial changes in water level and consequent shifts in macrophyte abundance. The oligotrophic period in the early 1900s is thought to represent the target trophic state for the lake. After the 1950s, introduction of vendace resulted in higher planktivory reflected by an increased relative abundance of small-bodied pelagic cladocerans. Signs of eutrophication occurred due to increased nutrient load. During the last 10 years, signs of recovery have been recorded. A complex history such as that of Lake Pyhäjärvi illustrates the difficulties in selecting management targets, and the risk of setting false targets, for lakes based solely on monitoring data-both neolimnological and palaeolimnological approach are needed.
... Også en stor tak til søgruppens øvrige AC&amp;#x27;ere, nu og gennem ti-den, for en stor ... more ... Også en stor tak til søgruppens øvrige AC&amp;#x27;ere, nu og gennem ti-den, for en stor indsats og de fælles bestræbelser på at få det hele til at gå op i en højere enhed på alle felter: Jens Peder Jensen, Torben Lauridsen, Su-sanne Lildal Amsinck, Rikke Bjerring Hansen, Asger Roer ...
Due date of deliverable: Month 12 Actual submission date: Month 12 Project co-funded by the Europ... more Due date of deliverable: Month 12 Actual submission date: Month 12 Project co-funded by the European Commission within the Seventh Framework Programme (2007-2013) Dissemination Level PU Public X PP Restricted to other programme participants (including the Commission Services) RE Restricted to a group specified by the consortium (including the Commission Services) CO Confidential, only for members of the consortium (including the Commission Services) Guidelines for indicator development Document history (and future) Version 1 produced by Daniel Hering and Sebastian Birk (UDE) by 15/12/09. Commented by the members of the WISER Steering Group by 4/1/10. Version 2 produced by UDE based on these comments. Commented by the relevant workpackage leaders and workpackage scientists (WP3.1 to 4.4) (by 31/1/10
Phytoplankton data from 606 lakes were used to characterize indicator taxa of near-pristine refer... more 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
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Papers by M. Søndergaard