Senter for biogeokjemi i antropocen
Jeg er leder av Senter for biogeokjemi i antropocen (CBA – Center for biogeochemistry in Anthropocene). CBA er et tverrfaglig senter bestående av ansatte ved Institutt for biovitenskap, Institutt for geofag og Kjemisk institutt ved Universitetet i Oslo. Vi kombinerer aktiviteter ved de tre instituttene for å studerer samspillet mellom klima, karbonkretsløpet og økosystemer i nordlige breddegrader.
Emneord:
Klima,
Evolusjon,
Økologi,
Genomstørrelse,
Økologisk støkiometri,
Pelagiske næringsnett
Publikasjoner
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Côté, Marianne; Englund, Göran; Andersen, Tom; Hessen, Dag Olav; Finstad, Anders Gravbrøt & Bélanger, Claude
[Vis alle 7 forfattere av denne artikkelen]
(2024).
Towards modeling data-poor lakes at the regional scale using parameters from data-rich lakes and relationships to lake characteristics.
INLAND WATERS.
ISSN 2044-2041.
doi:
10.1080/20442041.2023.2265798.
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Mjaaland, Marius Timmann; Hessen, Dag Olav & Eriksen, Thomas Hylland
(2024).
Antropocen - en introduksjon til menneskets tidsalder.
I Mjaaland, Marius Timmann; Eriksen, Thomas Hylland & Hessen, Dag Olav (Red.),
Antropocen - menneskets tidsalder.
Res Publica.
ISSN 9788282263016.
s. 7–29.
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Heuschele, Jan David; Andersen, Tom; Walseng, Bjørn & Hessen, Dag Olav
(2023).
Assessing climatic and spatial variables influencing zooplankton richness for space-for-time predictions.
Freshwater Biology.
ISSN 0046-5070.
69(1),
s. 64–73.
doi:
10.1111/fwb.14193.
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1. The macroecological drivers of freshwater diversity are accredited geographical, spatial and climatic variables, but also to productivity, ecosystem age and landscape history. Locally diversity is also influenced by the dispersal ability of species. Here we evaluated how spatial and climatic variables influence species richness and macroecological patterns in Cladocera and Copepoda. We also discuss
whether a space-for-time approach is suitable to predict the community's response to the current rapid warming of lakes.
2. We use the presence-absence of pelagic and littoral microcrustaceans in 1465 Norwegian lakes with a wide range of latitudinal, longitudinal, and altitudinal gradients, as well as a wide span in lake areas, to evaluate how spatial and climatic factors influence zooplankton diversity in two major groups: Cladocera and Copepoda.
3. Longitude and latitude per se were poor predictors of zooplankton richness, but a combination of spatial and ecological predictors gave a good spatial prediction
of cladoceran and copepod richness. These two groups did, however, not differ in their spatial distribution, with a strikingly fixed proportion of copepods close to 0.3, suggesting no obvious Allee- effects regarding the mode of reproduction (asexual vs sexual).
4. Since temperature alone was a poor predictor of species richness for both groups and dispersal constraints can make it very difficult to estimate a new richness
equilibrium under a future climate, space-for-time predictions may have limited value for assessing future patterns of microcrustacean diversity.
5. Based on a quite unique dataset in terms of the sheer number of sites, spatial gradients, and inclusion of littoral species, our study demonstrates that assessments
on how changing climate will shape and modulate zooplankton communities in the future are problematic.
biogeography, dispersal, diversity, lakes, micro-crustaceans
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Schultze, Sabrina; Andersen, Tom; Knudtzon, Nina; Ruus, Anders; Rundberget, Jan T. & Brooks, Steven J.
[Vis alle 9 forfattere av denne artikkelen]
(2023).
Do DOM quality and origin affect the uptake and accumulation of lipid-soluble contaminants in coastal filter feeders? An experimental simulation of teflubenzuron exposure to blue mussels.
Aquatic Toxicology.
ISSN 0166-445X.
263.
doi:
10.1016/j.aquatox.2023.106696.
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The increased export of terrestrial dissolved organic matter (terrDOM) to coastal marine ecosystems may affect local filter feeders and the local food web via the altered uptake of organic material and associated contaminants. To compare terrDOM to marine DOM (marDOM) as contaminant vectors to coastal biota, we exposed blue mussels (Mytilus sp.) to the different DOM types in combination with teflubenzuron, a widely applied lipophilic aquaculture medicine targeting salmon lice (Lepeophtheirus salmonis). A 16-day exposure of the blue mussels to DOM and teflubenzuron was followed by a depuration phase of 20 days without teflubenzuron. We calculated teflubenzuron adsorption rates and bioaccumulation factors (BAF) using a Bayesian model, expecting teflubenzuron uptake to be greater with terrDOM than marDOM due to the higher prevalence of large amphipathic humic acids in terrDOM. Humic acids have strong absorption properties and are able to envelope lipophilic molecules. Thus, humic acids can function as an efficient contaminant vector when taken up by filter feeders. Although there were varying degrees of overlap, the mussels tended to accumulate higher amounts of teflubenzuron in the DOM treatments than in the seawater control (bioaccumulation factor [BAF] in seawater: median 106 L/kg; 2.5 %–97.5 % percentile: 69–160 L/kg). Contrary to expectations, mussels exposed to marDOM showed a trend toward more bioaccumulation of teflubenzuron than those exposed to terrDOM (BAF marine 144 L/kg; 102–221 L/kg versus BAF terrestrial: 121 L/kg; 82–186 L/kg). The highest teflubenzuron accumulation was observed with the 50:50 mixture of marDOM and terrDOM (BAF mix: 165 L/kg; 117–244 L/kg). The slight difference in DOM-type accumulation rates observed in this experiment—especially the accumulation rate of terrDOM compared to that of the seawater-only treatment type—was not considered environmentally relevant. Further studies are necessary to see if the observed trends transfer to complex environmental systems.
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Crapart, Camille Marie; Finstad, Anders Gravbrøt; Hessen, Dag Olav; Vogt, Rolf David & Andersen, Tom
(2023).
Spatial predictors and temporal forecast of total organic carbon levels in boreal lakes.
Science of the Total Environment.
ISSN 0048-9697.
870.
doi:
10.1016/j.scitotenv.2023.161676.
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Browning of Fennoscandian boreal lakes is raising concerns for negative ecosystem impacts as well as reduced drinking water quality. Declined sulfur deposition and warmer climate, along with afforestation, other climate impacts and less outfield grazing, have resulted in increased fluxes of Total Organic Carbon (TOC) from catchments to freshwater, and subsequently to coastal waters. This study assesses the major governing factors for increased TOC levels among several catchment characteristics in almost 5000 Fennoscandian lakes and catchments.
Normalized Difference Vegetation Index (NDVI), a proxy for plant biomass, and the proportions of peatland in the catchment, along with surface runoff intensity and nitrogen deposition loading, were identified as the main spatial predictors for lake TOC concentrations. A multiple linear model, based on these explanatory variables, was used to simulate future TOC concentration in surface runoff from coastal drainage basins in 2050 and 2100, using the forecasts of climatic variables in two of the Shared Socio-economic Pathways (SSP): 1-2.6 (+2 °C) and 3-7.0 (+4,5 °C). These scenarios yield contrasting effects. SSP 1-2.6 predicts an overall decrease of TOC export to coastal waters, while SSP 3-7.0 in contrast leads to an increase in TOC export.
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Svendsen, Camilla; Amlund, Heidi; Carlsen, Monica Hauger; Eriksen, Gunnar Sundstøl; Husøy, Trine & Lillegaard, Inger Therese Laugsand
[Vis alle 27 forfattere av denne artikkelen]
(2022).
Food and chemical substances relevant for monitoring - Scientific Opinion of the Scientific Steering Committee of the Norwegian Scientific Committee for Food and Environment.
VKM Report.
ISSN 2535-4019.
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At request from the Norwegian Food Safety Authority (NFSA), VKM has identified food
groups and food items consumed by the Norwegian population that are relevant for
monitoring regarding content of one or more undesirable chemical substances (Figure 1).
Undesirable chemical substances were defined as chemical substances in food that may
constitute a potential health risk.
VKM has created a knowledge base (an Excel file) as a tool for planning and prioritising
monitoring of foods and undesirable chemical substances. The substance groups included in
the knowledge base are flavourings, food additives, metals and metalloids, natural toxins,
persistent organic pollutants, process-induced contaminants, substances in food contact
materials, substances in food supplements, and trace elements. More than 40 different
substances were included.
Food items that are known contributors to exposure to an undesirable chemical substance
were identified from quantitative and qualitative data, mainly from EFSA opinions and VKM
risk assessments. Four national dietary surveys were used for identification of food items and
food groups habitually eaten by the Norwegian population. The habitual diet was used to
identify potential unknown sources of the substances. The information on known and
unknown sources was compiled in a knowledge base comprised of 456 “undesirable chemical
substance/food item” pairs that were identified to be relevant for monitoring.
For each “undesirable chemical substance/food item” pair, the following information are
included in the knowledge base:
- Food category
- Contribution to total exposure, including degree of contribution
- Origin of occurrence data, and availability of Norwegian occurrence data
- Remarks regarding sampling
- Sources of the undesirable chemical substances in food
- Risk (a combined score for hazard and exposure)
Sampling of food is a complex area. Careful planning of the sampling strategy is needed and
several parameters should be taken into consideration, depending on the properties of the
chemical substance and the food item. Generic guidelines on sampling strategy, including
sample number and frequency, have been provided in the report.
Key words: VKM, health risk, monitoring, Norwegian Scientific Committee for Food and
Environment, Norwegian Food Safety Authority, undesirable chemical substance.
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Puts, Isolde Callisto; Ask, Jenny; Siewert, Matthias B.; Sponseller, Ryan A.; Hessen, Dag Olav & Bergström, Ann-Kristin
(2022).
Landscape determinants of pelagic and benthic primary production in northern lakes.
Global Change Biology.
ISSN 1354-1013.
28(23),
s. 7063–7077.
doi:
10.1111/gcb.16409.
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Walseng, Bjørn; Durant, Joël; Hessen, Dag Olav; Jerstad, Kurt; Nilsson, Anna & Røstad, Ole Wiggo
[Vis alle 7 forfattere av denne artikkelen]
(2022).
Long-term annual and spatial variation of polygyny in the white-throated dipper (Cinclus cinclus).
Ecology and Evolution.
ISSN 2045-7758.
12(10).
doi:
10.1002/ece3.9416.
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Mating strategies are key components in the fitness of organisms, and notably in birds the occurrence of monogamy versus polygyny has attracted wide interest. We address this by a very comprehensive dataset (2899 breeding events spanning the years 1978–2019) of the white-throated dipper Cinclus cinclus. Though the mating system of this species has been regarded as generally monogamous, we find that 7% of all breeding events were performed by polygynous males (approximately 15% of all pairs). The fraction of polygyny has been stable over the entire study period irrespective of population size. The assumption that polygyny is most common at low population density was not supported. Surprisingly, there was no difference between polygynous and monogamous males with regard to the quality of the territories they inhabited, ranked according to their overall frequency of use. The most common age group, first-year breeders, dominated among monogamous males, while among polygynous males second-year breeders were most common, followed by third and first-year breeders. The primary females were in general older than females mated to monogamous males, also when controlled for their general frequency in the population. The majority of the two females mated to a polygynous male, bred in the vicinity of each other. The probability for a male to be involved in polygyny more than once, was significantly higher than by chance, suggesting phenotypic quality differences among males.
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Anderson, Thomas R.; Hessen, Dag Olav; Gentleman, Wendy C.; Yool, Andrew & Mayor, Daniel J.
(2022).
Quantifying the roles of food intake and stored lipid for growth and development throughout the life cycle of a high-latitude copepod, and consequences for ocean carbon sequestration.
Frontiers in Marine Science.
ISSN 2296-7745.
9.
doi:
10.3389/fmars.2022.928209.
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Andersen, Lene Frost; Berstad, Paula; Bukhvalova, Barbara Alexandra; Carlsen, Monica Hauger; Dahl, Lisbeth Jane & Goksøyr, Anders
[Vis alle 35 forfattere av denne artikkelen]
(2022).
Benefit and risk assessment of fish in the Norwegian diet - Scientific Opinion of the Steering Committee of the Norwegian Scientific Committee for Food and Environment.
VKM Report.
ISSN 2535-4019.
2022(17).
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Wang, You-Ren; Hessen, Dag Olav; Samset, Bjørn Hallvard & Stordal, Frode
(2022).
Evaluating global and regional land warming trends in the past decades with both MODIS and ERA5-Land land surface temperature data.
Remote Sensing of Environment.
ISSN 0034-4257.
280.
doi:
10.1016/j.rse.2022.113181.
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Schultze, Sabrina; Andersen, Tom; Hessen, Dag Olav; Ruus, Anders; Borgå, Katrine & Poste, Amanda
(2022).
Land-cover, climate and fjord morphology drive differences in organic matter and nutrient dynamics in two contrasting northern river-fjord systems.
Estuarine, Coastal and Shelf Science.
ISSN 0272-7714.
270.
doi:
10.1016/j.ecss.2022.107831.
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Climate and land-use changes are leading to impacts on individual ecosystems as well as shifts in transfer dynamics between interconnected systems. At the land-ocean interface, changes in riverine inputs of organic matter (OM) and nutrients have the potential to lead to shifts in coastal carbon and nutrient cycling with consequences for ecosystem structure and function. In this study, we assess OM and nutrient dynamics for two contrasting Norwegian river-to-fjord systems: a boreal system with a forested catchment draining into a narrow fjord (‘narrow boreal system’), and a subarctic system where lowland forests and mountainous regions drain into a broad fjord (‘broad subarctic system’). We characterized seasonal organic carbon and nutrient concentrations and DOM absorption properties for samples collected along transects from river to outer fjord during 2015/2016. While differences in catchment properties drove contrasts in river chemistry between the two study rivers, fjord morphology and hydrodynamics as well as dissolved organic carbon (DOC) and nutrient concentrations in marine receiving waters predicted water-chemistry patterns along the transect. The narrow boreal system, with high riverine DOC and nutrient concentrations, was structured mainly by a horizontal salinity gradient from river to outer fjord, with limited impact of seasonality. In contrast, the broad subarctic system tended to be dominated by vertical salinity stratification, with strong between-date differences in surface water salinity linked to seasonality in river discharge. These dynamics were also reflected in the strong horizontal gradients in DOC, nutrients and DOM properties in the narrow boreal system, in contrast to the broad subarctic system, where strong seasonality paired with a lack of strong contrast between riverine and marine concentrations of DOC and most nutrients led to an uncoupling between salinity and other water chemistry variables. In the narrow boreal system, terrestrial OM dominated both the particulate and dissolved OM pools, while OM in the broad subarctic system was derived primarily from marine phytoplankton. Non-linear declines in NO3 + NO2 were observed consistently in the boreal system and during the productive spring season in the subarctic system, suggesting biological uptake and a potentially important role of these rivers as sources of bioavailable N to coastal ecosystems. The results from these two case studies highlight the complex and interacting effects of catchment land-cover, river water chemistry and discharge, fjord morphometry and hydrodynamics in structuring the transport, fate and potential impacts of terrestrially-derived nutrients and organic matter in northern coastal environments.
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Hanevik, Hans Ivar & Hessen, Dag Olav
(2022).
IVF and human evolution.
Human Reproduction Update.
ISSN 1355-4786.
28(4),
s. 457–479.
doi:
10.1093/humupd/dmac014.
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Humans are shaped by evolution through natural selection, as are all species. While evolution is central to all biological processes, the key stage for competition and selection is reproduction, which encompasses various events from courtship and mating to fertilization and pregnancy. In humans, IVF is used to aid the intrinsically inefficient reproduction by coitus, and in several countries, the proportion of children born after IVF is increasing. While IVF is an enabling technology for infertile patients, it also circumvents reproductive barriers and changes selection pressures. This grand theme review describes the systematic differences between IVF and coitus in selection pressures on reproducing cells, individuals and populations. At the cellular unit of selection, for example, IVF favours different traits in spermatozoa (fast swimmers over short distances) than coitus does (forward mobility over longer distances). Similarly, a male with low sperm quality and a female who decides to delay her first birth to an advanced age, can both increase their reproductive fitness by IVF compared to if reproduction by coitus is their only option. In as much as delayed reproduction is a cultural trait, IVF thus enables cultural practices that may in their turn affect human evolution. A main point in this review is to discuss the interactive effects of biological and cultural traits in the context of IVF, and how they act in concert as drivers towards increased demand for IVF. It is not the aim of this review to argue against IVF, which no doubt is a major medical advancement, but rather to examine IVF and human evolution from a broad perspective, including potential longer-term impacts. Since IVF is a young technology, the empirical data indicative of evolutionary effects of IVF in humans are sparse. In general, we argue that IVF facilitates the redirection of resources away from reproduction in humans, since reproduction by IVF bypasses some of the resource-demanding processes that reproduction by coitus entails. Hence, IVF sets the evolutionary stage for a human species increasingly reliant on, and adapted to, technological means of reproduction.
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Moe, Therese Fosholt; Hessen, Dag Olav & Demars, Benoît Olivier Laurent
(2021).
Juncus Bulbosus Tissue Nutrient Concentrations and Stoichiometry in Oligotrophic Ecosystems: Variability with Seasons, Growth Forms, Organs and Habitats.
Plants.
ISSN 2223-7747.
10(3).
doi:
10.3390/plants10030441.
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Aquatic plant nutrient concentrations provide important information to characterise their role in nutrient retention and turnover in aquatic ecosystems. While large standing biomass of aquatic plants is typically found in nutrient-rich localities, it may also occur in oligotrophic ecosystems. Juncus bulbosus is able to form massive stands even in very nutrient-dilute waters. Here we show that this may be achieved by tissues with very high carbon-to-nutrient ratios combined with perennial (slow) growth and a poor food source for grazers inferred from plant stoichiometry and tissue nutrient thresholds. We also show that the C, N, P and C:N:P stoichiometric ratios of Juncus bulbosus vary with the time of year, habitats (lakes versus rivers) and organs (roots versus shoots). We found no differences between growth forms (notably in P, inferred as the most limiting nutrient) corresponding to small and large plant stands. The mass development of J. bulbosus requires C, N and P, whatever the ecosystem (lake or river), and not just CO2 and NH4, as suggested in previous studies. Since macrophytes inhabiting oligotrophic aquatic ecosystems are dominated by isoetids (perennial plants with a high root/shoot ratio), attention should be paid to quantifying the role of roots in aquatic plant stoichiometry, nutrient turnover and nutrient retention.
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Bodin, Johanna Eva; Thorstensen, Tage; Alsheikh, Muath K; Basic, Dean; Edvardsen, Rolf Brudvik & Dalen, Knut Tomas
[Vis alle 41 forfattere av denne artikkelen]
(2021).
Genome editing in food and feed production – implications for risk assessment. Scientific Opinion of the Scientific Steering Committee of the Norwegian Scientific Committee for Food and Environment.
VKM Report.
ISSN 2535-4019.
2021(18).
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The Norwegian Scientific Committee for Food and Environment (VKM) initiated this work to
examine the extent to which organisms developed by genome-editing technologies pose new
challenges in terms of risk assessment.
This report considers whether the risk assessment guidance on genetically modified organisms,
developed by the European Food Safety Authority (EFSA), can be applied to evaluate potential
risks of organisms developed by genome editing.
Background
Gene technology has allowed for the transfer of genes between organisms and species, and
thereby to design altered genotypes with novel traits, i.e. GMOs. A new paradigm started in the
early 2000s with the development of genome-editing techniques. Unlike traditional genetic
modification techniques resulting in insertion of foreign DNA fragments at random locations in
the genome, the new genome-editing techniques additionally open for a few single nucleotide
edits or short insertions/deletions at a targeted site in an organism’s genome. These new
techniques can be applied to most types of organisms, including plants, animals and
microorganisms of commercial interest.
An important question is how the novel, genome-edited organisms should be evaluated with
respect to risks to health and the environment. The European Court of Justice decided in 2018
to include genome-edited organisms in the GMO definition and hence in the regulatory system
already in place. This implies that all products developed by genome-editing techniques must
be risk-assessed within the existing regulatory framework for GMOs. The European and
Norwegian regulatory frameworks regulate the production, import and placing on the market of
food and feed containing, consisting of or produced from GMOs, as well as the release of GMOs
into the environment.
The assessment draws on guidance documents originally developed by EFSA for risk
assessment of GMOs, which were drawn up mainly to address risks regarding insertion of
transgenes. The new genome-editing techniques, however, provide a new continuum of
organisms ranging from those only containing a minor genetic alteration to organisms
containing insertion or deletion of larger genomic regions.
Risk assessment of organisms developed by genome editing
The present discourse on how new genome-editing techniques should be regulated lacks an
analysis of whether risk assessment methodologies for GMOs are adequate for risk assessment
of organisms developed through the use of the new genome-editing techniques. Therefore, this
report describes the use of genome-editing techniques in food and feed production and
discusses challenges in risk assessment with the regulatory framework.
Specifically, this report poses the question as to whether the EFSA guidance documents are
sufficient for evaluating risks to health and environment posed by genome-edited plants,
animals and microorganisms. To address these questions, the report makes use of case
examples relevant for Norway. These examples, intended for food and feed, include oilseed
rape with a modified fatty acid profile, herbicide-tolerant and pest-resistant crops, sterile
salmon, virus-resistant pigs and hornless cattle. The report considers all aspects of the stepwise
approach as described in the EFSA guidance documents. Conclusions
The inherent flexibility of the EFSA guidance makes it suitable to cover health and
environmental risk assessments of a wide range of organisms with various traits and intended
uses. Combined with the embedded case-by-case approach the guidance is applicable to
genome-edited organisms. The evaluation of the guidance demonstrates that the parts of the
health and environmental risk assessment concerned with novel traits (i.e. the phenotype of the
organism) may be fully applied to all categories of genome-edited organisms. ............
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Baho, Didier Ludovic; Rizzuto, Simone; Nizzetto, Luca; Hessen, Dag Olav; Norberg, Jon & Skjelbred, Birger
[Vis alle 9 forfattere av denne artikkelen]
(2021).
Ecological Memory of Historical Contamination Influences the Response of Phytoplankton Communities.
Ecosystems.
ISSN 1432-9840.
24(7),
s. 1591–1607.
doi:
10.1007/s10021-021-00604-0.
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Ecological memory (EM) recognizes the importance of previous stress encounters in promoting community tolerance and thereby enhances ecosystem stability, provided that gained tolerances are preserved during non-stress periods. Drawing from this concept, we hypothesized that the recruitment of tolerant species can be facilitated by imposing an initial sorting process (conditioning) during the early stages of community assembly, which should result in higher production (biomass development and photosynthetic efficiency) and stable community composition. To test this, phytoplankton resting stages were germinated from lake sediments originating from two catchments that differed in contamination history: one impacted by long-term herbicides and pesticides exposures (historically contaminated lake) from an agricultural catchment compared to a low-impacted one (near-pristine lake) from a forested catchment. Conditioning was achieved by adding an herbicide (Isoproturon, which was commonly used in the catchment of the historically contaminated lake) during germination. Afterward, the communities obtained from germination were exposed to an increasing gradient of Isoproturon. As hypothesized, upon conditioning, the phytoplankton assemblages from the historically contaminated lake were able to rapidly restore photosynthetic efficiency (p > 0.01) and became structurally (community composition) more resistant to Isoproturon. The communities of the near-pristine lake did not yield these positive effects regardless of conditioning, supporting that EM was a unique attribute of the historically stressed ecosystem. Moreover, assemblages that displayed higher structural resistance concurrently yielded lower biomass, indicating that benefits of EM in increasing structural stability may trade-off with production. Our results clearly indicate that EM can foster ecosystem stability to a recurring stressor.
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Fontaine, Laurent; Khomich, Maryia; Andersen, Tom; Hessen, Dag Olav; Rasconi, Serena & Davey, Marie Louise
[Vis alle 7 forfattere av denne artikkelen]
(2021).
Multiple thresholds and trajectories of microbial biodiversity predicted across browning gradients by neural networks and decision tree learning.
ISME Communications.
ISSN 2730-6151.
1.
doi:
10.1038/s43705-021-00038-8.
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Ecological association studies often assume monotonicity such as between biodiversity and environmental properties although there is growing evidence that nonmonotonic relations dominate in nature. Here, we apply machine-learning algorithms to reveal the nonmonotonic association between microbial diversity and an anthropogenic-induced large-scale change, the browning of freshwaters, along a longitudinal gradient covering 70 boreal lakes in Scandinavia. Measures of bacterial richness and evenness (alpha-diversity) showed nonmonotonic trends in relation to environmental gradients, peaking at intermediate levels of browning. Depending on the statistical methods, variables indicative for browning could explain 5% of the variance in bacterial community composition (beta-diversity) when applying standard methods assuming monotonic relations and up to 45% with machine- learning methods taking non-monotonicity into account. This non-monotonicity observed at the community level was explained by the complex interchangeable nature of individual taxa responses as shown by a high degree of nonmonotonic responses of individual bacterial sequence variants to browning. Furthermore, the nonmonotonic models provide the position of thresholds and predict alternative bacterial diversity trajectories in boreal freshwater as a result of ongoing climate and land-use changes, which in
turn will affect entire ecosystem metabolism and likely greenhouse gas production.
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Eie, Martin; Jensen, Thomas Correll; Walseng, Bjørn; Eie, Jon Arne & Hessen, Dag Olav
(2021).
Long-term resilience in microcrustacean communities despite
environmental changes.
Ecosphere.
ISSN 2150-8925.
12(7),
s. 1–13.
doi:
10.1002/ecs2.3676.
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The ability of communities to withstand stress or maintain their species composition over extended periods of environmental changes is a matter of major concern. Here, we utilize a dataset where microcrustacean communities were related to water chemistry in 82 boreal-alpine lakes over a 50-yr time span (1968 and 2016), with the same person involved in sampling both times ensuring identical sites and
sampling protocols. Over this time span, there has been a 1–2°C increase in mean annual temperatures and prolonged growing seasons. Also, the strong changes in SO4 deposition and acidification, peaking in the early 1980s, followed by a recovery period, have caused not only an increase in pH but also a pronounced browning (elevated DOC) and reduced levels of Ca over the past three decades. Despite this, the microcrustacean diversity and community composition have remained remarkably stable, and this holds both for the species-rich larger, boreal sites and the species-poor alpine sites. While likely there are interannual fluctuations in species abundance, and perhaps species may also be missing for certain periods, a combination
of local refugia, resting egg seed-banks and a regional recolonization that may occur at the metapopulation
level, aims at maintaining a strong stability in community composition.
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Crapart, Camille Marie; Andersen, Tom; Hessen, Dag Olav; Valiente Parra, Nicolas & Vogt, Rolf David
(2021).
Factors Governing Biodegradability of Dissolved Natural Organic Matter in Lake Water.
Water.
ISSN 2073-4441.
13(16).
doi:
10.3390/w13162210.
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Eshun-Wilson, Franceen; Wolf, Raoul; Andersen, Tom; Hessen, Dag O & Sperfeld, Erik
(2020).
UV radiation affects antipredatory defense traits in Daphnia pulex.
Ecology and Evolution.
ISSN 2045-7758.
10(24),
s. 14082–14097.
doi:
10.1002/ece3.6999.
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In aquatic environments, prey perceive predator threats by chemical cues called kairomones, which can induce changes in their morphology, life histories, and behavior. Predator‐induced defenses have allowed for prey, such as Daphnia pulex, to avert capture by common invertebrate predators, such as Chaoborus sp. larvae. However, the influence of additional stressors, such as ultraviolet radiation (UVR), on the Daphnia–Chaoborus interaction is not settled as UVR may for instance deactivate the kairomone. In laboratory experiments, we investigated the combined effect of kairomones and UVR at ecologically relevant levels on induced morphological defenses of two D. pulex clones. We found that kairomones were not deactivated by UVR exposure. Instead, UVR exposure suppressed induced morphological defense traits of D. pulex juveniles under predation threat by generally decreasing the number of neckteeth and especially by decreasing the size of the pedestal beneath the neckteeth. UVR exposure also decreased the body length, body width, and tail spine length of juveniles, likely additionally increasing the vulnerability to Chaoborus predation. Our results suggest potential detrimental effects on fitness and survival of D. pulex subject to UVR stress, with consequences on community composition and food web structure in clear and shallow water bodies.
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Allesson, Lina; Koehler, Birgit; Thrane, Jan-Erik; Andersen, Tom & Hessen, Dag O
(2020).
The role of photomineralization for CO2 emissions in boreal lakes along a gradient of dissolved organic matter.
Limnology and Oceanography.
ISSN 0024-3590.
66(1),
s. 158–170.
doi:
10.1002/lno.11594.
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Many boreal lakes are experiencing an increase in concentrations of terrestrially derived dissolved organic matter (DOM)—a process commonly labeled “browning.” Browning affects microbial and photochemical mineralization of DOM, and causes increased light attenuation and hence reduced photosynthesis. Consequently, browning regulates lake heterotrophy and net CO2‐efflux to the atmosphere. Climate and environmental change makes ecological forecasting and global carbon cycle modeling increasingly important. A proper understanding of the magnitude and relative contribution from CO2‐generating processes for lakes ranging in dissolve organic carbon (DOC) concentrations is therefore crucial for constraining models and forecasts. Here, we aim to study the relative contribution of photomineralization to total CO2 production in 70 Scandinavian lakes along an ecosystem gradient of DOC concentration. We combined spectral data from the lakes with regression estimates between optical parameters and wavelength specific photochemical reactivity to estimate rates of photochemical DOC mineralization. Further, we estimated total in‐lake CO2‐production and efflux from lake chemical and physical data. Photochemical mineralization corresponded on average to 9% ± 1% of the total CO2‐evasion, with the highest contribution in clear lakes. The calculated relative contribution of photochemical mineralization to total in‐lake CO2‐production was about 3% ± 0.2% in all lakes. Although lakes differed substantially in color, depth‐integrated photomineralization estimates were similar in all lakes, regardless of DOC concentrations. DOC concentrations were positively related to CO2‐efflux and total in‐lake CO2‐production but negatively related to primary production. We conclude that enhanced rates of photochemical mineralization will be a minor contributor to increased heterotrophy under increased browning.
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Sperfeld, Erik; Nilssen, Jens Petter; Rinehart, Shelby Anne; Klaus, Schwenk & Hessen, Dag Olav
(2020).
Ecology of predator-induced morphological defense traits in Daphnia longispina (Cladocera, Arthropoda).
Oecologia.
ISSN 0029-8549.
192,
s. 687–698.
doi:
10.1007/s00442-019-04588-6.
Fulltekst i vitenarkiv
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Rizzuto, Simone; Thrane, Jan-Erik; Baho, Didier L; Jones, Kevin C.; Zhang, Hao & Hessen, Dag O
[Vis alle 8 forfattere av denne artikkelen]
(2020).
Water Browning Controls Adaptation and Associated Trade-Offs in Phytoplankton Stressed by Chemical Pollution.
Environmental Science and Technology.
ISSN 0013-936X.
54(9),
s. 5569–5579.
doi:
10.1021/acs.est.0c00548.
Fulltekst i vitenarkiv
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The acquisition of tolerance to an environmental stressor can result in organisms displaying slower growth after stress release. While well-grounded in the theory, empirical evidence of the trade-off between stress tolerance and organism fitness is scarce and blurred by the interaction with different environmental factors. Here, we report the effects of water browning on the responses, tolerance acquisition, and associated trade-offs in a population of microalgae exposed to sublethal concentrations of organic micropollutants over multiple generations. Our results show that dissolved organic matter (DOM) reduces toxic responses and modulates tolerance acquisition by the algae, possibly by complexing micropollutants. Microalgae that acquire tolerance allocate resources to fitness at the cost of reduced cell size. They yield higher productivity than nonadapted ones when grown in the presence of micropollutants but lower in their absence. The net trade-off was positive, indicating that adaptation can result in a higher productivity and fitness in tolerant species in recurrently stressed environments.
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Andersen, Tom; Hessen, Dag Olav; Håll, Johnny Peter; Khomich, Maryia; Kyle, Marcia & Lindholm, Markus
[Vis alle 10 forfattere av denne artikkelen]
(2020).
Congruence, but no cascade—Pelagic biodiversity across three trophic levels in Nordic lakes.
Ecology and Evolution.
ISSN 2045-7758.
10(15),
s. 8153–8165.
doi:
10.1002/ece3.6514.
Fulltekst i vitenarkiv
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Covariation in species richness and community structure across taxonomical groups (cross‐taxon congruence) has practical consequences for the identification of biodiversity surrogates and proxies, as well as theoretical ramifications for understanding the mechanisms maintaining and sustaining biodiversity. We found there to exist a high cross‐taxon congruence between phytoplankton, zooplankton, and fish in 73 large Scandinavian lakes across a 750 km longitudinal transect. The fraction of the total diversity variation explained by local environment alone was small for all trophic levels while a substantial fraction could be explained by spatial gradient variables. Almost half of the explained variation could not be resolved between local and spatial factors, possibly due to confounding issues between longitude and landscape productivity. There is strong consensus that the longitudinal gradient found in the regional fish community results from postglacial dispersal limitations, while there is much less evidence for the species richness and community structure gradients at lower trophic levels being directly affected by dispersal limitation over the same time scale. We found strong support for bidirectional interactions between fish and zooplankton species richness, while corresponding interactions between phytoplankton and zooplankton richness were much weaker. Both the weakening of the linkage at lower trophic levels and the bidirectional nature of the interaction indicates that the underlying mechanism must be qualitatively different from a trophic cascade.
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Bostad, Inga & Hessen, Dag Olav
(2019).
Learning and loving of nature in the Anthropocene. How to broaden science with curiosity and passion.
Studier i Pædagogisk Filosofi.
ISSN 2244-9140.
8(1),
s. 28–42.
doi:
10.7146/spf.v8i1.113924.
Fulltekst i vitenarkiv
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Baho, Didier L; Leu, Eva; Pomati, Francesco; Hessen, Dag O; Nordberg, Jon & Moe, S. Jannicke
[Vis alle 8 forfattere av denne artikkelen]
(2019).
Resilience of Natural Phytoplankton Communities to Pulse Disturbances from Micropollutant Exposure and Vertical Mixing.
Environmental Toxicology and Chemistry.
ISSN 0730-7268.
38(10),
s. 2197–2208.
doi:
10.1002/etc.4536.
Fulltekst i vitenarkiv
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Freshwaters are increasingly exposed to complex mixtures of pharmaceutical and personal care products (PPCPs) from municipal wastewater, which are known to alter freshwater communities’ structure and functioning. However, their interaction with other disturbances and whether their combined effects can impact ecological resilience (i.e., the ability of a system to tolerate disturbances without altering the system's original structure and processes) remain unexplored. Using in situ mesocosms in 2 lakes with different nutrient levels (mesotrophic and eutrophic), we assessed whether a pulse exposure to sublethal concentrations of 12 PPCPs affects the ecological resilience of natural phytoplankton communities that experienced an abrupt environmental change involving the destabilization of the water column through mixing. Such mixing events are predicted to increase as the effects of climate change unfold, leading to more frequent storms, which disrupt stratification in lakes and force communities to restructure. We assessed their combined effects on community metrics (biomass, species richness, and composition) and their relative resilience using 4 indicators (cross‐scale, within‐scale, aggregation length, and gap length), inferred from phytoplankton communities by discontinuity analysis. The mixing disturbance alone had negligible effects on the community metrics, but when combined with chemical contaminants significant changes were measured: reducing total biomass, species richness, and altered community composition of phytoplankton. Once these changes occurred, they persisted until the end of the experiment (day 20), when the communities’ structures from the 2 highest exposure levels diverged from the controls. The resilience indicators were not affected by PPCPs but differed significantly between lakes, with lower resilience found in the eutrophic lake. Thus, PPCPs can significantly alter community structures and reinforce mechanisms that maintain ecosystems in a “degraded state.”
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Weyhenmeyer, Gesa A; Hartmann, Jens; Hessen, Dag O; Kopáček, Jiří; Hejzlar, Josef & Jacquet, Stéphan
[Vis alle 29 forfattere av denne artikkelen]
(2019).
Widespread diminishing anthropogenic effects on calcium in freshwaters.
Scientific Reports.
ISSN 2045-2322.
9.
doi:
10.1038/s41598-019-46838-w.
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Calcium (Ca) is an essential element for almost all living organisms. Here, we examined global variation and controls of freshwater Ca concentrations, using 440 599 water samples from 43 184 inland water sites in 57 countries. We found that the global median Ca concentration was 4.0 mg L−1 with 20.7% of the water samples showing Ca concentrations ≤ 1.5 mg L−1, a threshold considered critical for the survival of many Ca-demanding organisms. Spatially, freshwater Ca concentrations were strongly and proportionally linked to carbonate alkalinity, with the highest Ca and carbonate alkalinity in waters with a pH around 8.0 and decreasing in concentrations towards lower pH. However, on a temporal scale, by analyzing decadal trends in >200 water bodies since the 1980s, we observed a frequent decoupling between carbonate alkalinity and Ca concentrations, which we attributed mainly to the influence of anthropogenic acid deposition. As acid deposition has been ameliorated, in many freshwaters carbonate alkalinity concentrations have increased or remained constant, while Ca concentrations have rapidly declined towards or even below pre-industrial conditions as a consequence of recovery from anthropogenic acidification. Thus, a paradoxical outcome of the successful remediation of acid deposition is a globally widespread freshwater Ca concentration decline towards critically low levels for many aquatic organisms.
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Baho, Didier L; Pomati, Francesco; Leu, Eva; Hessen, Dag O; Moe, S Jannicke & Norberg, Jon
[Vis alle 7 forfattere av denne artikkelen]
(2019).
A single pulse of diffuse contaminants alters the size distribution of natural phytoplankton communities.
Science of the Total Environment.
ISSN 0048-9697.
683,
s. 578–588.
doi:
10.1016/j.scitotenv.2019.05.229.
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The presence of a multitude of bioactive organic pollutants collectively classified as pharmaceuticals and personal care products (PPCPs) in freshwaters is of concern, considering that ecological assessments of their potential impacts on natural systems are still scarce. In this field experiment we tested whether a single pulse exposure to a mixture of 12 pharmaceuticals and personal care products, which are commonly found in European inland waters, can influence the size distributions of natural lake phytoplankton communities. Size is one of the most influential determinants of community structure and functioning, particularly in planktonic communities and food webs. Using an in-situ microcosm approach, phytoplankton communities in two lakes with different nutrient levels (mesotrophic and eutrophic) were exposed to a concentration gradient of the PPCPs mixture at five levels. We tested whether sub-lethal PPCPs doses affect the scaling of organisms' abundances with their size, and the slope of these size spectra, which describe changes in the abundances of small relative to large phytoplankton. Our results showed that a large proportion (approximately 80%) of the dataset followed a power-law distribution, thus suggesting evidence of scale invariance of abundances, as expected in steady state ecosystems. PPCPs were however found to induce significant changes in the size spectra and community structure of natural phytoplankton assemblages. The two highest treatment levels of PPCPs were associated with decreased abundance of the most dominant size class (nano-phytoplankton: 2–5 μm), leading to a flattening of the size spectra slope. These results suggest that a pulse exposure to PPCPs induce changes that potentially lead to unsteady ecosystem states and cascading effects in the aquatic food webs, by favoring larger non-edible algae at the expense of small edible species. We propose higher susceptibility due to higher surface to volume ratio in small species as the likely cause of these structural changes.
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Moe, Therese F; Hessen, Dag O & Demars, Benoît O L
(2019).
Functional biogeography: Stoichiometry and thresholds for interpreting nutrient limitation in aquatic plants.
Science of the Total Environment.
ISSN 0048-9697.
677,
s. 447–455.
doi:
10.1016/j.scitotenv.2019.04.366.
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Atmospheric N pollution may shift nutrient limitations in aquatic autotrophs from N to P or cause an intensification of P limitation in formerly pristine areas. Small changes in nutrient supply in oligotrophic lakes and rivers could lead to large changes in relative plant growth and yield with possible knock on effects on ecosystem carbon cycling through changes in the decomposition rate of their tissue. Previous biogeographical studies have shown inconsistent responses of plant nutrient tissue content and stoichiometry (functional traits) to external nutrient availability. Here we used a single species, Juncus bulbosus, to test the interplay between plant tissue nutrient (content and stoichiometry) and external environmental factors (local and catchment scale). We developed a comparative approach applicable globally to assess the thresholds for nutrient limitation in aquatic plants in the wild. Phosphorus in Juncus bulbosus tissue was negatively related to sediment organic matter (Fe root plaque limiting P uptake) and catchment vegetation cover (less P leaching to lakes). Our comparative approach revealed that the lack of increase in N plant tissue along the strong gradient in external N concentration may be explained by P limitation and strict plant tissue N:P ratio. Our comparative approach further showed that the nutrient content and stoichiometry of Juncus bulbosus was similar to other submerged aquatic plants growing in nutrient poor aquatic ecosystems. In southern Norway, mass development of Juncus bulbosus may be primarily triggered by changes in P availability, rather than CO2 or inorganic N, as previously thought, although co-limitations are also possible. If so, the mass development of Juncus bulbosus in oligotrophic aquatic ecosystems could be an early indicator of increasing P fluxes through these ecosystems which are less limited by N due to high atmospheric N deposition.
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Jensen, Thomas Correll; Walseng, Bjørn; Hessen, Dag Olav; Dimante-Deimantovica, Inta; Novichkova, Anna A. & Chertoprud, Elena S.
[Vis alle 11 forfattere av denne artikkelen]
(2019).
Changes in trophic state and aquatic communities in high Arctic ponds in response to increasing goose populations.
Freshwater Biology.
ISSN 0046-5070.
64(7),
s. 1241–1254.
doi:
10.1111/fwb.13299.
Vis sammendrag
1. The high Arctic, including the Svalbard archipelago in the North Atlantic, has been
exposed to direct and indirect drivers of climatic change such as rising temperatures
and associated changes in hydrology and nutrient fluxes. In addition, the
number of migrating birds, particularly geese, increased remarkably in the Svalbard
archipelago during the second half of the last century. The higher number of
breeding birds potentially affects water quality and the biota in ponds and lakes.
2. We aimed to investigate the potential influence of increasing goose abundance on
trophic state, taxon richness, and species composition of freshwater communities
in the high Arctic. We hypothesised that higher goose abundance affects the
trophic state of shallow lakes and ponds and their taxon richness and species composition.
We conducted a survey of selected ponds at Svalbard along a goose
abundance gradient. We used the number of area-specific goose droppings (range
of 0–94 droppings m2) as a proxy of goose presence and measured proxies for
productivity as well as taxon richness and composition of phytoplankton and invertebrate
communities.
3. Presence and abundance of geese were associated with higher productivity of
ponds. Invertebrate and phytoplankton taxon richness correlated (positively) with
goose abundance. Both phytoplankton and invertebrate taxon richness increased
with increasing nitrogen (N) concentrations. Goose abundance significantly affected
phytoplankton species composition, while concentrations of total-N and
total phosphorus (P) did not. Species composition of aquatic invertebrates was
most strongly affected by goose abundance, but the effect of total-N concentration
was also significant.
4. Increased goose abundance was associated with bird driven nutrient enrichment,
increased phytoplankton and invertebrate taxon richness and changes of these
biological communities. Thus, in addition to climate change, the higher abundances
of large migratory water fowl in many polar areas may pose a major additional stress to arctic lakes and ponds. In fact, climate change and bird impact may interact,
accelerating ongoing environmental change of arctic freshwater ecosystems.
climate change, geese, invertebrates, phytoplankton, Svalbard
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Hessen, Dag Olav; Jensen, Thomas Correll & Walseng, Bjørn
(2019).
Zooplankton diversity and dispersal by birds; Insights from different geographical scales.
Frontiers in Ecology and Evolution.
ISSN 2296-701X.
7,
s. 1–11.
doi:
10.3389/fevo.2019.00074.
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Given the major ecological and evolutionary role of dispersal abilities for organisms, as well as the current interest in species' potential for further migration and colonization as a result of climatic changes or human-mediated invasions, our knowledge about dispersal abilities on spatial and temporal scales in many taxa is surprisingly limited. Zooplankton inhabit lakes and ponds that functionally are “aquatic islands” in the landscape, and both community composition and richness depend on their ability to disperse, and their post-dispersal colonization abilities. We here assess the diversity and dispersal of freshwater microcrustaceans based on three types of data; (1) > 2000 lakes on mainland Norway spanning a wide range in longitude, latitude and altitude, (2) a more limited number of ponds at Svalbard that are differently affected by migrating birds, and (3) immigration and colonization of recently constructed wetlands and man-made ponds. At all scales we discuss whether observed patterns in diversity can be explicitly linked to birds as vectors, or if confounding factors such as climate, productivity, age of locality—or other means of immigration, precludes conclusive evidence. The spatial patterns of zooplankton distribution strongly suggest that local sorting is a major determinant of richness and community composition. This sorting may not necessarily lead to similar community composition (the “quorum effect”) however. Despite the fact that rapid colonization occurs at local scales, and that birds undoubtedly can transmit animals or resting stages, their role in modulating community structure and richness is still an unsettled issue due to the many confounding parameters. The fact that birds often play a dual role in shaping diversity and community composition, first by direct dispersal, and secondly via affecting post-dispersal species sorting by changing water quality and productivity, is an important aspect of zoochory. Direct experimental evidence (colonization with and without bird exclusion), or genetic analysis of zooplankton species along migration routes, would however be the only ways to establish firm evidence for this case of zoochory.
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Yu, ChaoQing; Huang, Xiao; Chen, Han; Godfray, H. Charles J.; Wright, Jonathon S. & Hall, Jim W.
[Vis alle 25 forfattere av denne artikkelen]
(2019).
Managing nitrogen to restore water quality in China.
Nature.
ISSN 0028-0836.
567,
s. 516–520.
doi:
10.1038/s41586-019-1001-1.
Vis sammendrag
The nitrogen cycle has been radically changed by human activities1
.
China consumes nearly one third of the world’s nitrogen fertilizers.
The excessive application of fertilizers2,3
and increased nitrogen
discharge from livestock, domestic and industrial sources have
resulted in pervasive water pollution. Quantifying a nitrogen
‘boundary’4
in heterogeneous environments is important for
the effective management of local water quality. Here we use a
combination of water-quality observations and simulated nitrogen
discharge from agricultural and other sources to estimate spatial
patterns of nitrogen discharge into water bodies across China from
1955 to 2014. We find that the critical surface-water quality standard
(1.0 milligrams of nitrogen per litre) was being exceeded in most
provinces by the mid-1980s, and that current rates of anthropogenic
nitrogen discharge (14.5 ± 3.1 megatonnes of nitrogen per year)
to fresh water are about 2.7 times the estimated ‘safe’ nitrogen
discharge threshold (5.2 ± 0.7 megatonnes of nitrogen per year).
Current efforts to reduce pollution through wastewater treatment
and by improving cropland nitrogen management can partially
remedy this situation. Domestic wastewater treatment has helped
to reduce net discharge by 0.7 ± 0.1 megatonnes in 2014, but at
high monetary and energy costs. Improved cropland nitrogen
management could remove another 2.3 ± 0.3 megatonnes of
nitrogen per year—about 25 per cent of the excess discharge to fresh
water. Successfully restoring a clean water environment in China
will further require transformational changes to boost the national
nutrient recycling rate from its current average of 36 per cent to
about 87 per cent, which is a level typical of traditional Chinese
agriculture. Although ambitious, such a high level of nitrogen
recycling is technologically achievable at an estimated capital
cost of approximately 100 billion US dollars and operating costs
of 18–29 billion US dollars per year, and could provide co-benefits
such as recycled wastewater for crop irrigation and improved
environmental quality and ecosystem services.
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Se alle arbeider i Cristin
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Wiik-Nielsen, Jannicke; Renslebråten, Line & Hessen, Dag Olav
(2023).
Tett på livet i vann.
Fontini forlag.
ISBN 978-82-8373-185-9.
143 s.
-
Marianne, Sletbakk; Arnodd, Håpnes; Hessen, Dag Olav; Kristin, Martinsen & Eskeland, Ragnhild
(2022).
Bios 2 Biologi 2 (LK20) .
Cappelen Damm Akademisk.
ISBN 9788202743253.
432 s.
-
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Wiik-Nielsen, Jannicke; Mathismoen, Ole & Hessen, Dag Olav
(2020).
Tett på insekter og småkryp.
Fontini forlag.
ISBN 978-82-8373-088-3.
135 s.
-
Sletbakk, Marianne; Håpenes, Arnodd; Hessen, Dag Olav; Eskeland, Ragnhild; Gjærevoll, Inger & Borge, Ole Johan
(2019).
BIOS 2.
Cappelen Damm AS.
ISBN 9788202604851.
Se alle arbeider i Cristin
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Opdal, Anders Martin Frugård; Andersen, Tom; Hessen, Dag Olav; Lindemann, Christian & Aksnes, Dag Lorents
(2023).
Tracking freshwater browning and coastal water darkening from boreal forests to the Arctic Ocean.
-
Hessen, Dag Olav & Opdal, Anders Martin Frugård
(2023).
Linking Forest to Fish: A Story of Coastal Darkening.
SIL news (The International Association of Theoretical and Applied Limnology).
doi:
10.5281/zenodo.8009398.
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Jensen, Thomas Correll; Schartau, Ann Kristin; Majaneva, Markus; Veraart, A.J.; Hessen, Dag Olav & Eiler, Alexander
[Vis alle 8 forfattere av denne artikkelen]
(2023).
Bird impacts on biological communities in Arctic ponds.
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Schultze, Sabrina; Langva, Hilde K.; Knudtzon, Nina Cathrine; Chatzigeorgiou, Marios; Rundberget, Jan Thomas & Brooks, Steven
[Vis alle 11 forfattere av denne artikkelen]
(2023).
Terrestrial dissolved organic matter is not an efficent vector for lipohilic contaminants in filter feeders.
-
Bjorå, Charlotte Sletten; Elven, Reidar & Hessen, Dag Olav
(2023).
Hva skjer med plantene i Norge? .
[Radio].
NRK P2 EKKO.
-
Jensen, Thomas Correll; Schartau, Ann Kristin; Majaneva, Markus; Hessen, Dag Olav; Eiler, Alexander & Loonen, Maarten J.J.E.
[Vis alle 7 forfattere av denne artikkelen]
(2023).
Bird impacts on biological communities in Arctic ponds – preliminary results.
-
Melteig, Elina; Vandvik, Vigdis & Hessen, Dag Olav
(2022).
Verdens land er nå enige om å beskytte naturen.
[Fagblad].
forskning.no.
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Hessen, Dag Olav; Samset, Bjørn Hallvard & Kverndokk, Snorre
(2022).
Vil naturen rydde opp etter festen?
.
NRK Ytring.
-
Einevoll, Gaute & Hessen, Dag Olav
(2022).
Podcast #60: Om hvordan livet oppstod .
[Internett].
Podcast "Vett og vitenskap".
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Samset, Bjørn Hallvard; Hessen, Dag Olav; Sverdrup-Thygeson, Anne & Einevoll, Gaute
(2022).
Kunnskap for en ny tid.
NRK.no.
-
Alexander, Jan; Hemre, Gro Ingunn; Hofshagen, Merete; Mathisen, Gro Haarklou; Aasmo-Finne, Merethe & Agdestein, Angelika
[Vis alle 21 forfattere av denne artikkelen]
(2022).
Matproduksjon, mattrygghet og miljø - innspill om kunnskapsbehov til gjennomføringen av det grønne skiftet - Uttalelse fra hovedkomiteen i Vitenskapskomiteen for mat og miljø (VKM).
VKM Report.
ISSN 2535-4019.
2022:30(30),
s. 1–21.
Fulltekst i vitenarkiv
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Hanevik, Hans Ivar & Hessen, Dag Olav
(2022).
In vitro-fertilisering – nye metoder, nye muligheter, nye mennesker.
Tidsskrift for Den norske legeforening.
ISSN 0029-2001.
142(16).
doi:
10.4045/tidsskr.22.0578.
-
Schultze, Sabrina; Langva, Hilde K.; Nina, Knudtzon; Chatzigeorgiou, Marios; Rundberget, Thomas & Brooks, Steven
[Vis alle 11 forfattere av denne artikkelen]
(2022).
Effect of terrestrial and aquatic dissolved organic matter on uptake of teflubenzuron in mussels and ascidians.
-
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Schultze, Sabrina; Andersen, Tom; Knudtzon, Nina Cathrine; Ruus, Anders; Rundberget, Jan Thomas & Brooks, Steven
[Vis alle 9 forfattere av denne artikkelen]
(2021).
Effect of terrestrial and aquatic dissolved organic matter on uptake rates of teflubenzuron in blue mussels (M. edulis).
-
Einevoll, Gaute & Hessen, Dag Olav
(2021).
Podcast #45: Om verdens vippepunkter.
[Internett].
Podcast: Vett og vitenskap med Gaute Einevoll.
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Bergsjø, Leonora Onarheim; Jemterud, Torkild; Hessen, Dag Olav & Vistnes, Arnt Inge
(2021).
Abels Tårn – NRK Radio, 2021, 1. oktober. Panelet tar tidsmaskin til 1821.
[Radio].
NRK.
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Hessen, Dag Olav
(2021).
Vi trenger en hippokratisk ed for de ufødte.
Tidsskrift for Den norske legeforening.
ISSN 0029-2001.
141(12),
s. 1–5.
doi:
10.4045/tidsskr.21.0593.
-
Bryn, Anders; Dalen, Thea Grobstok; Finne, Eirik Aasmo; Heiberg, Hanne; Keetz, Lasse Torben & Nilsen, Irene Brox
[Vis alle 30 forfattere av denne artikkelen]
(2021).
Natur i endring - samspillet mellom klima og økosystemene.
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Vogt, Rolf David; Crapart, Camille Marie; Lie, Ragnar & Hessen, Dag Olav
(2021).
Effects of climate change and other regional drivers on Dissolved Natural Organic Matter .
-
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Allesson, Lina; Andersen, Tom; Dörsch, Peter; Eiler, Alexander; Wei, Jing & Hessen, Dag Olav
(2020).
Corrigendum: Phosphorus Availability Promotes Bacterial DOC-Mineralization, but Not Cumulative CO2-Production (Front.Microbiol, (2020), 11, (569879), 10.3389/fmicb.2020.569879).
Frontiers in Microbiology.
ISSN 1664-302X.
11.
doi:
10.3389/fmicb.2020.614974.
-
Vandvik, Vigdis; Elvevoll, Edel O.; Finne, Merethe Aasmo; Hofshagen, Merete; Nielsen, Anders & Steffensen, Inger-Lise
[Vis alle 21 forfattere av denne artikkelen]
(2020).
Uavhengige kunnskapssynteser: grunnlag for kunnskapsbaserte beslutninger i samfunnet. Uttalelse fra hovedkomiteen i Vitenskapskomiteen for mat og miljø (VKM) .
VKM Report.
ISSN 2535-4019.
2020:03,
s. 1–24.
-
Bryn, Anders; Hessen, Dag Olav & Stordal, Frode
(2020).
Før det bikker over.
Klassekampen.
ISSN 0805-3839.
s. 18–19.
-
Hessen, Dag Olav
(2019).
Publiseringspirater og akademiske kappløp.
I Tjora, Aksel (Red.),
Universitetskamp.
Scandinavian Academic Press.
ISSN 978-82-304-0247-4.
s. 43–56.
Vis sammendrag
Store endringer preger universitets- og høyskolesektoren i hele den vestlige verden. Også de norske institusjonene har opplevd betydelige reformer, blant annet knyttet til fusjoner og andre strukturendringer, profesjonalisering av ledelse og administrasjon, samt økt bruk av målstyring. Mange av endringene skaper bekymringer og motstand fra mange av sektorens ansatte, som brenner for sin forskning, for sine studenter, for sine kolleger og sin disiplin, for sitt arbeid og sine ideer, og for troen på at arbeidet bidrar positivt til kunnskap som kommer hele samfunnet til gode. Det er ikke en endringsfrykt som sådan, men en bekymring for at den nye virkeligheten vil kunne redusere sektorens egenart og rolle som samfunnsinstitusjon.
I denne boka analyseres slike endringer ved bruk av ulike perspektiver, teorier og erfaringer. Forfatterne har et ønske om å utvikle kritiske innspill og legge grunnlaget for en mer velinformert og perspektivrik diskusjon av endringer i sektoren og dens samfunnsrolle. Et underliggende spørsmål dreier seg om de siste tiders reformer synes å kunne ødelegge universiteters og høyskolers mulighet til å bidra med solid og samfunnsrelevant utdanning, forskning, formidling og innovasjon.
Boka vil være av interesse både for forskere, studenter, politikere og andre med interesse for sektorens utvikling. Håpet er at antologiens kapitler kan bidra til en kritisk refleksjon om endringer som vi også ser i samfunnet mer generelt.
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McGovern, Maeve; Evenset, Anita; Borgå, Katrine; Wit, Heleen de; Braaten, Hans Fredrik Veiteberg & Hessen, Dag Olav
[Vis alle 9 forfattere av denne artikkelen]
(2019).
Implications of Coastal Darkening for Contaminant Transport, Bioavailability, and Trophic Transfer in Northern Coastal Waters.
Environmental Science and Technology.
ISSN 0013-936X.
53(13),
s. 7180–7182.
doi:
10.1021/acs.est.9b03093.
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The increased transport of terrestrially derived organic material (tOM) from catchments to rivers and lakes is leading to browning of northern freshwaters.(1) Although the same environmental drivers can be expected to lead to widespread increases in tOM and subsequent darkening in adjacent coastal systems,(2) this has received considerably less attention, and long-term monitoring data for detecting these changes are scarce. This is despite expectations that darkening is likely to have a range of implications for coastal biogeochemistry and food-web ecology.
tOM is accompanied by other catchment-derived materials including contaminants, inorganic particles, and nutrients. Together, these terrestrial inputs can affect cycling and food-web accumulation of contaminants, in particular, methyl mercury (MeHg) and persistent organic pollutants (POPs). Because of the human and ecosystem health risks associated with these contaminants, and to ensure informed policy decisions, there is a need for a better understanding of the drivers of darkening and their direct and indirect impacts on the transport, bioavailability, and trophic transfer of contaminants in northern coastal waters.
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Jensen, Thomas Correll; Walseng, Bjørn; Hessen, Dag Olav; Dimante-Deimantovica, Inta; Novichkova, Anna & Chertoprud, Elena S.
[Vis alle 11 forfattere av denne artikkelen]
(2019).
Konsekvenser av økte gåsebestander i Arktis; næringsanriking og endret biomangfold i ferskvann.
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Banet, Catherine; Sørensen, Astrid; Bjørndal, Mette Helene; Fuhrman, Jay; Hessen, Dag Olav & Sebastian, Hole Markus
[Vis alle 16 forfattere av denne artikkelen]
(2022).
Negative emissions and carbon dioxide removal (CDR) including ocean scenarios: Drivers, uncertainties, and deployment potential.
Norges teknisk-naturvitenskapelige universitet.
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Negative emissions and Carbon Dioxide Removal
(CDR) at scale is required to offset hard to reduce
emission streams and remove historic emissions from
the atmosphere. CDR relies on and intervenes with the basics of earth systems such as the ocean, land, soil, and the atmosphere. This implies that CDR will need to be developed
on terms that are acceptable to the natural systems
which our human systems rely on.
This report offers an introduction to three CDR solutions: seaweed farming, BECCS and direct air capture (DAC).
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Skåre, Janneche Utne; Alexander, Jan; Haave, Marte; Jakubowicz, Ignacy; Knutsen, Helle Katrine & Lusher, Amy
[Vis alle 26 forfattere av denne artikkelen]
(2019).
Microplastics; occurrence, levels and
implications for environment and human health related to food. Scientific opinion of the
Scientific Steering Committee of the Norwegian Scientific Committee for Food and
Environment.
Norwegian Scientific Committee for Food and Environment (VKM).
ISSN 978-82-8259-332-8.
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Steffensen, Inger-Lise; Fæste, Christiane Kruse; Husøy, Trine; Knutsen, Helle Katrine; Mathisen, Gro Haarklou & Ørnsrud, Robin
[Vis alle 20 forfattere av denne artikkelen]
(2019).
Ranking of substances for monitoring in foods, drinks and
dietary supplements - based on risk and knowledge gaps. Scientific Opinion of the Scientific Steering Committee of the Norwegian Scientific Committee for Food and Environment.
Norwegian Scientific Committee for Food and Environment (VKM).
ISSN 978-82-8259-329-8.
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Källqvist, Torsten; Eklo, Ole Martin; Låg, Marit; Rakkestad, Kirsten Eline; Sipinen, Ville Erling & Steffensen, Inger-Lise
[Vis alle 23 forfattere av denne artikkelen]
(2019).
Genetically
modified glyphosate tolerant maize, soybean and oilseed rape versus conventionally grown
varieties – agricultural practices, residues of glyphosate, other pesticides and metabolites,
and implications for toxicity. Opinion of the Scientific Steering Committee of the Norwegian
Scientific Committee for Food and Environment (VKM).
Scientific Steering Committee of the Norwegian Scientific Committee for Food and Environment.
ISSN 978-82-8259-322-9.
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Publisert
20. apr. 2012 12:20
- Sist endret
7. des. 2021 08:53