| 1. |
- Donis, Daphne, et al.
(författare)
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Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer
- 2021
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Ingår i: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 66:12, s. 4314-4333
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Tidskriftsartikel (refereegranskat)abstract
- To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.
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| 2. |
- Mantzouki, Evanthia, et al.
(författare)
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Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins
- 2018
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Ingår i: Toxins. - : MDPI. - 2072-6651. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.
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| 3. |
- Adamik, Barbara, et al.
(författare)
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Estimation of the Severeness Rate, Death Rate, Household Attack Rate and the Total Number of COVID-19 Cases Based on 16 115 Polish Surveillance Records
- 2020
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Estimating the actual number of COVID-19 infections is crucial for steering through the COVID-19 pandemic crisis. It is, however, notoriously difficult, as many cases have no or only mild symptoms. Surveillance data for in-household secondary infections offers unbiased samples for COVID-19 prevalence estimation.Methods: We analyse 16 115 Polish surveillance records to obtain key figures of the COVID-19 pandemic. We propose conservative upper and lower bound estimators for the number of SARS-CoV-2 infections. Further, we estimate age-dependent bounds on the severe case rate, death rate, and the in-household attack rate.Results: By maximum likelihood estimates, the total number of COVID-19 cases in Poland as of July 22nd, 2020, is at most around 13 times larger and at least 1.6 times larger than the recorded number. The lower bound on the severeness rate ranges between 0.2% for the 0–39 year-old to 5.7% for older than 80, while the upper bound is between 2.6% and 34.1%. The lower bound on the death rate is between 0.04% for the age group 40–59 to 1.34% for the oldest. Overall, the severeness and death rates grow exponentially with age. The in-household attack ratio is 8.18% for the youngest group and 16.88% for the oldest.Conclusions: The proposed approach derives highly relevant figures on the COVID-19 pandemic from routine surveillance data, under assumption that household members of detected infected are tested and all severe cases are diagnosed.
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