Effect of removing small (<150μm) chironomids on inferring temperature in cold lakes

Sieving samples for chironomid analysis with a 150μm mesh was shown to greatly reduce sample preparation time, and use of only larger specimens did not affect chironomid-inferred salinities in African lakes. Here, we tested if this method is suitable for temperature reconstruction in colder lakes at higher latitudes. Removal of specimens 150μm) than those obtained with the full model (all specimens >100μm). General patterns of temperature change were also altered. For Lake 7 on Southampton Island, Canada, a cooling trend was reconstructed with the full Canadian model while the modified Canadian model yielded a warming trend. When only specimens >150μm were used, two to three times more wet sediment was needed to obtain a sufficient number of head capsules. These results indicate that, in cold lakes (mean July/August air temperature ≤11°C), large proportions of head capsules are <150 μm, and sieving the samples in a 150μm mesh leads to altered temperature reconstruction

Biological intercalibration: Invertebrates 2018

Project manager Heleen de WitThe 22nd biological intercalibration of invertebrates in the ICP Waters programme included four laboratories. The intercalibration is important for harmonising taxonomic work across countries, and is of high value in programmes where the focus is on community analyses, e.g. for the classification of ecological status according to the EU Water Framework Directive. The laboratories correctly identified 96 % of the species and 97% of the genera. The mean Quality assurance index ranged between 85 and 99. No laboratories had a mean value below 80 – the limit for acceptable taxonomic work. Trends in biological intercalibration of invertebrates from the initial intercalibration in 1992 to 2018 are presented, showing that the Qi has remained above 80% for the full period, suggesting skilled taxonomists in the laboratories affiliated to ICP Waters. For individual invertebrate groups, the laboratories perform best for caddis flies and worst for stoneflies. The Quality assurance index increased steadily during the first 22 years and has seemingly decreased during the last three years, possibly because of an increase in difficulty.Norwegian Environment Agency; United Nations Economic Commission for Europe (UNECE)publishedVersio

Predation by Eurasian otters on adult Atlantic salmon

The return of the Eurasian otter to western Norway has sparked human-predator conflicts as otters prey on vulnerable Atlantic salmon populations. Although predation may not be the direct cause of salmon population declines, otters that kill salmon in rivers before they spawn may impact the salmon spawning stock, with potential consequences for stock recruitment. Concerns of local people and stakeholders suggest that otter predation inhibits recovery of salmon populations. However, there is limited information on mortality caused by otter predation on adult salmon. To gain insight into impacts of otter predation on salmon populations, I quantified the predation by otters on adult salmon in two rivers in Western Norway using a novel combination of radiotelemetry and temperature loggers. I tagged 45 salmon in Aureelva and 30 salmon in Søre Vartdalselva and tracked the salmon until they died or left the river. This method identified the fates of 95 % of tagged salmon. Otters killed 9 tagged salmon in Aureelva and 20 tagged salmon in Søre Vartdalselva. I found no evidence that otters selectively killed salmon based on sex, length, health status or activity level, which suggests that predation mortality on pre-spawners was additive. Otter predation contributed in reducing both salmon populations below their spawning targets, and without otter predation both populations would have been closer to reaching their spawning targets. However, the magnitude of predation differed greatly between rivers. Salmon in Søre Vartdalselva had greater predation risk compared to salmon in Aureelva, possibly due to differences in the number of holding pools between the two rivers. The findings from this study emphasise that management decisions should be guided by river-specific evaluations of impacts of otter predation on salmon, for which the combination of radiotelemetry and temperature loggers can provide a valuable tool.Predation by Eurasian otters on adult Atlantic salmonpublishedVersio

Biological intercalibration: Invertebrates 2022

Prosjektleder: Kari AustnesThe ICP Waters biological intercalibration of invertebrates was executed to harmonise taxonomic work across countries and is of high value in programmes where the focus is on community analyses, e.g., for the classification of ecological status according to the EU Water Framework Directive. The 26th biological intercalibration of invertebrates in ICP Waters included two participants. A total 95 % of the species and 99 % of the genera were correctly identified in 2022. The mean Quality assurance index (Qi) ranged from 80.7 to 97.5 The results show that the average Qi has remained above 80% since 1992, suggesting skilled taxonomists in the laboratories affiliated to ICP Waters.Norwegian Ministry of Climate and Environment United Nations Economic Commission for Europe (UNECE)publishedVersio

TRENDS AND DEVELOPMENT IN CHIRONOMID PALAEOECOLOGY: SUMMARY FROM THE

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Behavioural response of brown trout (Salmo trutta) to total dissolved gas supersaturation in a regulated river

Total dissolved gas supersaturation from dams and power stations is a chronic freshwater pollutant that is toxic to animals with aquatic respiration. Laboratory ecotoxicology experiments have revealed capacity for captive fishes to saturoregulate by moving deeper, but field ecotoxicology research is largely lacking. We instrumented 94 brown trout in the Rysstad basin of the Otra River, Norway, with depth sensor acoustic transmitters and monitored their movements for 10 months. We found that the depths used by the trout largely protected them from the effects of total dissolved gas supersaturation, which ranged from 96% to 133% total gas pressure during the study. The depth use of fish was affected by sun position, lunar phase and spatial position in the river (i.e., available depth), and there was an extremely weak effect of total dissolved gas supersaturation that was counterintuitive (i.e., positive slope, movement toward surface). Depth traces of the fish revealed that nine fish died during the study, mostly coinciding with the first wave of supersaturation, consistent with observations of untagged dead fish with signs of gas bubble trauma found on the river bottom during this period (May-June). Overall, tagged trout exposure to total dissolved gas supersaturation depended on their use of depth, but responses to waves of extreme supersaturation at supraphysiological levels were weak and biologically insignificant, with individual variation and spatial position in the river most important in the model. Exposure to total dissolved gas supersaturation was mediated by individual differences in habitat use, which may be linked to activity and other traits that determine overall vulnerability to exposure to total dissolved gas supersaturation.publishedVersio

Annual changes in aquatic plant photosynthesis in the regulated river Otra and the effect of plant removal

Prosjektleder: Benoît O.L. DemarsMass development of submerged aquatic plants is often seen as nuisance for human activities. The present study used novel methods to estimate the changes in ecosystem photosynthesis (mostly Juncus bulbosus), through an annual cycle, under varying dissolved gas supersaturation events in the Rysstad basin, Otra River. The methods and results from this study may help us to understand the dynamics between supersaturation, J. bulbosus and fish health, and guide management decisions on aquatic plant removal.Krypsivprosjektet på Sørlandet (KPS). Sekretariat: Fylkesmannen i Agder, MiljøvernavdelingenpublishedVersio

Assessment of the risk to Norwegian biodiversity from import and keeping of American bison, European bison, domesticated water buffalo and domesticated yak.Scientific Opinion of the Panel on Alien Organisms and Trade in Endangered Species of the Norwegian Scientific Committee for Food and Environment

publishedVersio

Assessment of the risk to Norwegian biodiversity from import and keeping of American bison, European bison, domesticated water buffalo and domesticated yak. Scientific Opinion of the panel on Alien Organisms and Trade in Endangered Species (CITES) of the Norwegian Scientific Committee for Food and Environment

publishedVersio

Risk assessment of the predatory mite Stratiolaelaps scimitus for biological control of varroa mites in beehives : Scientific opinion of the panel on plant health of the Norwegian scientific committee for food and environment

Source at https://vkm.no/.publishedVersio