Torben L. Lauridsen

Torben L. Lauridsen
Aarhus University | AU · Department of Bioscience

M.Sc., PhD

About

224
Publications
99,003
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17,347
Citations
Citations since 2017
75 Research Items
7807 Citations
201720182019202020212022202302004006008001,0001,2001,400
201720182019202020212022202302004006008001,0001,2001,400
201720182019202020212022202302004006008001,0001,2001,400
201720182019202020212022202302004006008001,0001,2001,400

Publications

Publications (224)
Article
Full-text available
Since its inception, the theory of alternative equilibria in shallow lakes has evolved and been applied to an ever wider range of ecological and socio-ecological systems. The theory posits the existence of two alternative stable states or equilibria, which in shallow lakes are characterised by either clear water with abundant plants or turbid water...
Article
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Shallow lakes produce and emit substantial amounts of methane (CH4). Part of the CH4 produced in lakes is consumed by methane-oxidizing bacteria (MOB) present in the sediment and water column, thus reducing the overall CH4 emissions. However, the role of aquatic plants as habitat for CH4 oxidation by MOB is poorly understood. In this study, we comp...
Article
Full-text available
Zooplankton grazing at similar nutrient levels is generally regarded as lower in brackish than in freshwater lakes, but experimental evidence of this is lacking. Accordingly, we conducted short-term zooplankton grazing experiments in bottles with water from 12 Danish brackish lakes covering a large gradient in salinity (0.3–17.4‰) and nutrient conc...
Article
Characteristics of bottom sediments in lake mesocosms 11 years after starting the experiment were studied in order to determine the effects of nutrient loading, temperature increase and vegetation type on concentration and vertical distribution of phosphorus (P) forms. The experimental setup consisted of 24 outdoor flow-through mesocosms with two n...
Article
Fish larvae play an important structuring role for their prey and show ontogenetic shifts in diet. Changes in diet differ between species and habitats and may also be affected by turbidity (eutrophication). We investigated the diet (stomach content) and the food selection (ratio of ingested prey and prey availability) of roach and perch larvae in a...
Article
The structure and functioning of Arctic ecosystems have been drastically modified by global warming, with fish species potentially performing habitat shifts such as the northern expansion of generalist and warm-adapted species. The freshwater fish species Arctic charr (Salvelinus alpinus, hereafter charr) plays a key role in Arctic lake food webs,...
Article
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Roach (Rutilus rutilus) and perch (Perca fluviatilis) are dominant species in northern-temperate lakes of Europe, their relative importance depending on trophic state and habitat complexity. We studied the habitat distribution of roach and perch over a 15-year period in two Danish lakes, Lake Vaeng, undergoing major changes in water clarity and mac...
Article
Full-text available
Cross-latitude studies on lakes have a potential to predict how global warming may cause major changes in phytoplankton biomass and composition, e.g., the development of favourable conditions for cyanobacteria dominance. However, results from these studies may be influenced by biogeographical factors, and the conclusions may, therefore, not hold wh...
Article
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Copepods are important contributors to the zooplankton community in lakes. Being ‘‘sandwiched’’ between predators and resources, they are sensitive to changes in the environment. It has been proposed that the proportion of calanoids of total copepod abundance or biomass could be a valuable indicator of eutrophication. We investigated relationships...
Article
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The succession-driven reed bed habitat hosts a unique flora and fauna including several endangered invertebrate species. Reed beds can be managed through commercial winter harvest, with implications for reed bed conservation. However, the effects of winter harvest on the invertebrate community are not well understood and vary across studies and tax...
Article
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We analysed long-term monitoring data on submerged macrophytes and water chemistry from 666 Danish lakes > 1 hectare and mean depth < 3 m, encompassing a total of 1447 lake years. Our aim was to describe how plant cover (COV), plant volume inhabited (PVI) and species richness related to physical and chemical and environmental variables. Boosted reg...
Article
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A mesocosm experiment was conducted in a temperate eutrophic lake with the hypotheses: 1) the addition of a labile form of DOC would trigger a more pronounced response in phytoplankton biomass and composition compared with a non-labile form; 2) DOC addition would increase phytoplankton biomass by co-inserting organic nutrients for phytoplankton gro...
Article
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Human-induced changes in external nutrient loading affect the phytoplankton community and abundance directly by changing the amount of nutrients available, but also indirectly through changes in the zooplankton (that is, grazer) community structure, mediated in part by changes in the fish community structure and biomass. Such shifts affect the spec...
Article
Full-text available
Constructed wetlands have become a widely used tool for reducing nutrient loading from agriculture drainage water running to aquatic ecosystems. To ensure a high nutrient removal efficiency, it is often suggested to use macrophytes to retain or remove nutrients via uptake and through the denitrifying biofilm. In Europe, Phragmites australis and Typ...
Article
Full-text available
Disentangling the effects of climate change on nature is one of the main challenges facing ecologists nowadays. Warmer climates forces strong effects on lake biota for fish, leading to a reduction in size, changes in diet, more frequent reproduction, and stronger cascading effects. Space-for-time substitution studies (SFTS) are often used to unrave...
Article
Shallow lakes, the most numerous waterbodies on Earth, are susceptible to climate warming and nutrient enrichment whose effects on the microbial functional potentials are not yet fully understood, however. Here, we applied a microarray-based technology termed GeoChip 5.0 to investigate microbial functional genes at the beginning of April in shallow...
Article
Seasonal and annual dynamics of the zooplankton community in lakes are affected by changes in abiotic drivers, trophic interactions (e.g., changes in phytoplankton and fish communities and abundances) and habitat characteristics (e.g. macrophyte abundance and composition). However, little is known about the temporal responses of the zooplankton com...
Chapter
Excluding the delta lakes, which form and disappear according to the path of large rivers, the distribution of lakes and ponds in the Arctic is largely controlled by glacial history and the presence of permafrost. Another major category of Arctic lakes is the thermokarst lakes formed due to local permafrost degradation, rendering these lakes and po...
Article
The Eurasian otter (Lutra lutra) is a semi-aquatic predator that lives in a wide range of aquatic habitats. Knowledge of the diet of predators is essential for the management and conservation of the species and their habitats. We assessed the diet of otters in fifty-three faecal samples (spraints) by morphological analysis of undigested prey remain...
Article
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Global changes (e.g., warming and population growth) affect nutrient loadings and temperatures , but global warming also results in more frequent extreme events, such as heat waves. Using data from the world's longest-running shallow lake experimental mesocosm facility, we studied the effects of different levels of nutrient loadings combined with v...
Article
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Phytoplankton usually responds directly and fast to environmental fluctuations, making them useful indicators of lake ecosystem changes caused by various stressors. Here, we examined the phytoplankton community composition before, during, and after a simulated 1-month heat wave in a mesocosm facility in Silkeborg, Denmark. The experiment was conduc...
Article
Full-text available
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 zooplankt...
Article
Question Reed beds, dominated by common reed (Phragmites australis), have high ecological value. Several studies have examined the differences between managed and unmanaged reed beds without taking into account the time passed since the last management. In this paper, we seek to answer the question: how does the time passed since last management an...
Article
Aquatic macrophytes grow abundantly in many lowland streams and play a key role in ecosystem functioning, such as nutrient retention. In this study, we performed a microcosm experiment to quantify and compare the contribution of two freshwater macrophyte growth forms to nutrient cycling. We measured and compared inorganic nitrogen (NH4–N and NO3–N)...
Article
World-wide, reducing the external nutrient loading to lakes has been the primary priority of lake management in the restoration of eutrophic lakes over the past decades, and as expected this has resulted in an increase in the local environmental heterogeneity, and thus biotic heterogeneity, within lakes. However, little is known about how the regio...
Article
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 7...
Article
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During the past century, many brackish shallow lakes worldwide have become eutrophic. How the zooplankton have responded to this development is not well elucidated. Here, we analysed the decadal changes (from 1999-2000 to 2017-2018) in zooplankton biomass, body mass, and potential top-down control on phytoplankton during summer in 4 Danish shallow...
Article
Full-text available
Rapid climate changes may potentially have strong impacts on the ecosystem structure and nutrient dynamics of lakes as well as implications for water quality. We used a space-for-time approach to elucidate such possible effects by comparing data from 1656 shallow lakes (mean depth <3 m) in north temperate Denmark (DK) and subtropical Florida (FL)....
Article
Submerged macrophytes are important contributors to primary production in clear water arctic and low arctic lakes. However, their production and potential coverage are hampered by the harsh climate conditions. In this study, we investigated the potential for increased macrophyte production and coverage in arctic lakes in a future warmer climate. In...
Article
1. Breeding waterbird communities have suffered globally from the effects of anthropogenic changes in water quality (especially nutrient enrichment) in recent decades, but few studies have demonstrated the positive effects of restorative actions. 2. Annual breeding waterbird surveys in the period 1977-2005 at two restored southern Danish lake basi...
Article
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Food supply in the aquatic environment is very important for growth and survival of fish. Fish species of Lake Volta exhibit large feeding flexibility and may modify their habits during their growth. This study analyzed the diet of major fish species (Chrysichthys nigrodigitatus, Tilapia zillii, Bagrus bajad, Alestes baremoze, Synodontis velifer) i...
Conference Paper
Full-text available
Food supply in the aquatic environment is very important for growth and survival of fish. Fish species of Lake Volta exhibit large feeding flexibility and may modify their habits during their growth. This study aimed at analyzing the diet of major fish species (Chrysichthys nigrodigitatus, Tilapia zillii, Bagrus bajad, Alestes baremoze, Synodontis...
Article
The pelagic fishery of Lake Tanganyika, which is largely made up of the three species Lates stappersii, Limnothrissa miodon, and Stolothrissa tanganicae, has been in decline, and there is no clear understanding of the primary underlying causes. It has been suggested that climate change has altered the primary productivity of the system, but detaile...
Article
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A mass balance model of trophic interactions among ten key functional producer and consumer groups in Lake Volta was constructed using the Ecopath model to study the energy flows and species interactions in the lake. The present study was based on secondary and primary data on fish catch, diet composition, phytoplankton and zooplankton biomasses, c...
Article
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Common pochard Aythya ferina are rapidly declining globally, partly due to water quality change at breeding habitats. Lake restoration at two southern Danish lakes (external nutrient loading reduction, bream Abramis brama and roach Rutilus rutilus removal and stocking of pike Esox lucius) improved water clarity and submerged macrophyte cover. Nesti...
Article
Local glaciers and ice caps (GICs) comprise only ~5.4% of the total ice volume, but account for ~14–20% of the current ice loss in Greenland. The glacial history of GICs is not well constrained, however, and little is known about how they reacted to Holocene climate changes. Specifically, in North Greenland, there is limited knowledge about past GI...
Article
Full-text available
It is a generally accepted theory that ecological functions are enhanced with increased diversity in plant communities due to species complementarity effects. We tested this theory in a mesocosm study using freshwater submerged plant beds to determine if increasing species number caused overyielding and species complementarity. We applied a maximum...
Article
Full-text available
Globally, aquaculture production is faced with numerous challenges, notable among which is water quality. The study determined seasonal environmental changes in Lake Volta and its implications on cage production of Nile tilapia, Oreochromis niloticus in experimental and commercial farm (Sun Woo Farm) set-ups. For each set-up, three cages were used,...
Article
Full-text available
We studied community-environment relationships of lake macrophytes at two metacommunity scales using data from 16 regions across the world. More specifically, we examined (a) whether the lake macrophyte communities respond similar to key local environmental factors, major climate variables and lake spatial locations in each of the regions (i.e., wi...
Article
Sound decisions on the management of fish stocks depend on knowledge about the species composition, number, biomass and size structure of existing populations. Accordingly, the ability to make solid population estimates is essential. In this study, a 2.15 ha lake was completely drained and the total number of fish was recorded and amounted to 180,9...
Article
Full-text available
Constructed wetlands have become a widespread mean to reduce nutrient loading from tile drained agricultural areas. As a supplement to emergent plants usually present in these wetlands, submerged plants may, if present, enhance nutrient retention by occupying the deeper zones of the wetland basins. The nutrient retention efficiency may, however, va...
Preprint
Full-text available
The articel "Synergy between nutrients and warming enhances methane ebullition from experimental lakes" was published in Nature Climate Change 6 months ago.
Article
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Rising global sea level caused by melting ice sheets poses a major challenge in a persistently warming climate. The Greenland Ice Sheet (GrIS) is among the main contributors, and in order to make accurate predictions of future ice retreat and sea level rise, it is imperative to understand how the ice sheet responded to global warming in the past. R...
Article
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Fish can alter food web structure through trophic cascades. While most studies conducted in oligotrophic subarctic lakes show strong top–down control on consumers in the presence of fish, several studies undertaken in eutrophic subarctic Lake Mývatn, Iceland, suggest that it is consumer–resource interactions that drive the whole-lake community. Her...
Article
Full-text available
Fish species assemblage and selected environmental variables were monitored in Lake Volta from September 2014 to August 2016 to determine seasonal variability in species composition, catch and environmental variables that determine the structure of the fish community. A total of 1,557 individual fish belonging to 41 species, 25 genera and 13 famili...
Article
We analysed changes in the abundance, biomass and cell size of the microbial food web community (bacteria, heterotrophic nanoflagellates, ciliates) at contrasting nutrient concentrations and temperatures during a simulated heat wave. We used 24 mesocosms mimicking shallow lakes in which two nutrient levels (unenriched and enriched by adding nitroge...
Article
Full-text available
Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submer...
Article
Full-text available
Link to read only version of the paper "http://rdcu.be/FhSR". Lakes and ponds are important natural sources of the potent greenhouse gas methane (CH4), with small shallow waters identified as particular hotspots1,2. Ebullition (bubbles) of CH4 makes up a large proportion of total CH4 flux3,4. However, difficulty measuring such episodic events5 ma...
Technical Report
Full-text available
The European Water Framework Directive (WFD) requires the national classifications of good ecological status to be harmonised through an intercalibration exercise. In this exercise, significant differences in status classification among Member States are harmonized by comparing and, if necessary, adjusting the good status boundaries of the national...
Article
1. Trophic cascade studies have so far mostly focused on changes in the abundance, biomass, or average size of prey and predators. In contrast, individual size-based interactions, playing a key role in the trophic structure and functioning of aquatic ecosystems, have been less explored. 2. We conducted a 3-month in situ experiment in Lake Myvatn, I...
Article
Full-text available
Lakes in Greenland are species-poor ecosystems and many are fishless. We studied the structuring role of fish in lakes in high- and low-Arctic Greenland. Major differences were observed in the trophic structure of the 87 lakes studied. Pelagic zooplankton biomass was on average 3–4-fold higher in the fishless lakes and dominated by large-bodied tax...
Article
Full-text available
Body size, coupled with abundance and taxonomy, may help to understand the mechanisms shaping community structure. Since the body size of fish is closely related to their trophic niche, size diversity (based on individual body size) of fish communities may capture intraspecific variations in fish trophic niches that are not detected by species dive...
Article
Mining of gravel and sand for construction purposes is big business and gravel pit lakes have become increasingly common all over the world. In Denmark, hundreds of gravel pit lakes have been created during the past decades. We investigated the chemical and biological status of 33-52 gravel pit lakes and compared the results with data from similar-...
Article
Full-text available
Summary 1. Carbon (C) and nitrogen (N) stable isotope composition (15N:14N, d15N and 13C:12C, d13C) have been widely used to elucidate changes in aquatic ecosystem dynamics created by eutrophication and climate warming, often, however, without accounting for seasonal variation. 2. Here, we aim to determine the factors controlling the stable isotope...
Article
Full-text available
We used data on nutrients, chlorophyll a (Chla) and submerged macrophyte cover from up to 817 Danish lakes to elucidate seasonal variations in nitrogen (N) and phosphorus (P) concentrations and to study the impact of N or its role in combination with P. In both deep and shallow lakes, we found marked seasonality in the ratio between total N and tot...
Article
Full-text available
The ongoing global climate change involves not only increased temperatures but may also produce more frequent extreme events, such as severe rainfall that could trigger a pulse of nutrients to lakes. In shallow lakes, this may affect primary producers through a number of direct and indirect mechanisms. We conducted a six-month mesocosm experiment t...
Conference Paper
Globally, aquaculture production is faced with numerous challenges, notable among which is water quality. The study determined seasonal environmental changes in Lake Volta and its implications on cage production of Nile tilapia, Oreochromis niloticus in experimental and commercial farm (Sun Woo Farm) set-ups. For each set-up, three cages were used,...
Book
Full-text available
The European Water Framework Directive (WFD) requires the national classifications of good ecological status to be harmonised through an intercalibration exercise. In this exercise, significant differences in status classification among Member States are harmonized by comparing and, if necessary, adjusting the good status boundaries of the national...
Data
The European Water Framework Directive (WFD) requires the national classifications of good ecological status to be harmonised through an intercalibration exercise. In this exercise, significant differences in status classification among Member States are harmonized by comparing and, if necessary, adjusting the good status boundaries of the national...