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Bacteriophages, or phages, are viruses that infect and replicate within bacterial hosts, playing a significant role in regulating microbial populations and ecosystem dynamics. However, phages from extreme environments such as polar regions remain relatively understudied due to challenges such as restricted ecosystem access and low biomass. Understanding the diversity, structure, and functions of polar phages is crucial for advancing our knowledge of the microbial ecology and biogeochemistry of these environments. In this review, we will explore the current state of knowledge on phages from the Arctic and Antarctic, focusing on insights gained from -omic studies, phage isolation, and virus-like particle abundance data. Metagenomic studies of polar environments have revealed a high diversity of phages with unique genetic characteristics, providing insights into their evolutionary and ecological roles. Phage isolation studies have identified novel phage–host interactions and contributed to the discovery of new phage species. Virus-like particle abundance and lysis rate data, on the other hand, have highlighted the importance of phages in regulating bacterial populations and nutrient cycling in polar environments. Overall, this review aims to provide a comprehensive overview of the current state of knowledge about polar phages, and by synthesizing these different sources of information, we can better understand the diversity, dynamics, and functions of polar phages in the context of ongoing climate change, which will help to predict how polar ecosystems and residing phages may respond to future environmental perturbations., https://lnu.se/en/research/research-projects/project-exploring-the-virioneuston-viral-bacterial-interactions

Forecasting river flow is crucial for optimal planning, management, and sustainability using freshwater resources. Many machine learning (ML) approaches have been enhanced to improve streamflow prediction. Hybrid techniques have been viewed as a viable method for enhancing the accuracy of univariate streamflow estimation when compared to standalone approaches. Current researchers have also emphasised using hybrid models to improve forecast accuracy. Accordingly, this paper conducts an updated literature review of applications of hybrid models in estimating streamflow over the last five years, summarising data preprocessing, univariate machine learning modelling strategy, advantages and disadvantages of standalone ML techniques, hybrid models, and performance metrics. This study focuses on two types of hybrid models: parameter optimisation-based hybrid models (OBH) and hybridisation of parameter optimisation-based and preprocessing-based hybrid models (HOPH). Overall, this research supports the idea that meta-heuristic approaches precisely improve ML techniques. It's also one of the first efforts to comprehensively examine the efficiency of various meta-heuristic approaches (classified into four primary classes) hybridised with ML techniques. This study revealed that previous research applied swarm, evolutionary, physics, and hybrid metaheuristics with 77%, 61%, 12%, and 12%, respectively. Finally, there is still room for improving OBH and HOPH models by examining different data pre-processing techniques and metaheuristic algorithms., Validerad;2023;Nivå 2;2023-11-14 (marisr);Full text license: CC BY

The most critical step for methylmercury (MeHg) bioaccumulation in aquatic food webs is phytoplankton uptake of dissolved MeHg. Dissolved organic matter (DOM) has been known to influence MeHg uptake, but the mechanisms have remained unclear. Here we show that the concentration of DOM-associated thiol functional groups (DOM-RSH) varies substantially across contrasting aquatic systems and dictates MeHg speciation and bioavailability to phytoplankton. Across our 20 study sites, DOM-RSH concentrations decrease 40-fold from terrestrial to marine environments whereas dissolved organic carbon (DOC), the typical proxy for MeHg binding sites in DOM, only has a 5-fold decrease. MeHg accumulation into phytoplankton is shown to be directly linked to the concentration of specific MeHg binding sites (DOM-RSH), rather than DOC. Therefore, MeHg bioavailability increases systematically across the terrestrial-marine aquatic continuum as the DOM-RSH concentration decreases. Our results strongly suggest that measuring DOM-RSH concentrations will improve empirical models in phytoplankton uptake studies and will form a refined basis for modeling MeHg incorporation in aquatic food webs under various environmental conditions.

Despite their small spatial extent, fluvial ecosystems play a significant role in processing and transporting carbon in aquatic networks, which results in substantial emission of methane (CH4) into the atmosphere. For this reason, considerable effort has been put into identifying patterns and drivers of CH4 concentrations in streams and rivers and estimating fluxes to the atmosphere across broad spatial scales. However, progress toward these ends has been slow because of pronounced spatial and temporal variability of lotic CH4 concentrations and fluxes and by limited data availability across diverse habitats and physicochemical conditions. To address these challenges, we present a comprehensive database of CH4 concentrations and fluxes for fluvial ecosystems along with broadly relevant and concurrent physical and chemical data. The Global River Methane Database (GriMeDB; 10.6073/pasta/f48cdb77282598052349e969920356ef, Stanley et al., 2023) includes 24ĝ€¯024 records of CH4 concentration and 8205 flux measurements from 5029 unique sites derived from publications, reports, data repositories, unpublished data sets, and other outlets that became available between 1973 and 2021. Flux observations are reported as diffusive, ebullitive, and total CH4 fluxes, and GriMeDB also includes 17ĝ€¯655 and 8409 concurrent measurements of concentrations and 4444 and 1521 fluxes for carbon dioxide (CO2) and nitrous oxide (N2O), respectively. Most observations are date-specific (i.e., not site averages), and many are supported by data for 1 or more of 12 physicochemical variables and 6 site variables. Site variables include codes to characterize marginal channel types (e.g., springs, ditches) and/or the presence of human disturbance (e.g., point source inputs, upstream dams). Overall, observations in GRiMeDB encompass the broad range of the climatic, biological, and physical conditions that occur among world river basins, although some geographic gaps remain (arid regions, tropical regi

Methane (CH4) is a potent greenhouse gas and its concentrations have tripled in the atmosphere since the industrial revolution. There is evidence that global warming has increased CH4 emissions from freshwater ecosystems 1,2, providing positive feedback to the global climate. Yet for rivers and streams, the controls and the magnitude of CH4 emissions remain highly uncertain 3,4. Here we report a spatially explicit global estimate of CH4 emissions from running waters, accounting for 27.9 (16.7–39.7) Tg CH4 per year and roughly equal in magnitude to those of other freshwater systems 5,6. Riverine CH4 emissions are not strongly temperature dependent, with low average activation energy (EM = 0.14 eV) compared with that of lakes and wetlands (EM = 0.96 eV) 1. By contrast, global patterns of emissions are characterized by large fluxes in high- and low-latitude settings as well as in human-dominated environments. These patterns are explained by edaphic and climate features that are linked to anoxia in and near fluvial habitats, including a high supply of organic matter and water saturation in hydrologically connected soils. Our results highlight the importance of land–water connections in regulating CH4 supply to running waters, which is vulnerable not only to direct human modifications but also to several climate change responses on land.

The planktonic realm from bacteria to zooplankton provides the baseline for pelagic aquatic food webs. However, multiple trophic levels are seldomly included in time series studies, hampering a holistic understanding of the influence of seasonal dynamics and species interactions on food web structure and biogeochemical cycles. Here, we investigated plankton community composition, focusing on bacterio-, phyto- and large mesozooplankton, and how biotic and abiotic factors correlate at the Linnaeus Microbial Observatory (LMO) station in the Baltic Sea from 2011 to 2018. Plankton communities structures showed pronounced dynamic shifts with recurring patterns. Summarizing the parts of the planktonic microbial food web studied here to total carbon, a picture emerges with phytoplankton consistently contributing > 39% while bacterio- and large mesozooplankton contributed ~ 30% and ~ 7%, respectively, during summer. Cyanophyceae, Actinobacteria, Bacteroidetes, and Proteobacteria were important groups among the prokaryotes. Importantly, Dinophyceae, and not Bacillariophyceae, dominated the autotrophic spring bloom whereas Litostomatea (ciliates) and Appendicularia contributed significantly to the consumer entities together with the more traditionally observed mesozooplankton, Copepoda and Cladocera. Our findings of seasonality in both plankton composition and carbon stocks emphasize the importance of time series analyses of food web structure for characterizing the regulation of biogeochemical cycles and appropriately constraining ecosystem models.

In the context of the European Union (EU) Drinking Water Directive, freshwater mussels (Order Unionoida: Bivalvia) can help us face the challenges of safe drinking water provisions for all citizens in the EU. Specifically, the implementation of high frequency noninvasive (HFNI) valvometers allows the early detection of eventual pollution events in drinking water treatment plants. Currently real-time behavioral analysis is deployed in a number of EU countries, and we foresee a bright future as new technological advances are developed concerning HFNI valvometers.

In the context of the European Union (EU) Drinking Water Directive, freshwater mussels (Order Unionoida: Bivalvia) can help us face the challenges of safe drinking water provisions for all citizens in the EU. Specifically, the implementation of high frequency noninvasive (HFNI) valvometers allows the early detection of eventual pollution events in drinking water treatment plants. Currently real-time behavioral analysis is deployed in a number of EU countries, and we foresee a bright future as new technological advances are developed concerning HFNI valvometers.

En stor del av de mänskligt orsakade utsläppen av koldioxid har tagits upp av haven. Men många av de svenska kusterna är idag påverkade av övergödning, vilket gör dem till en källa till växthusgaser, främst i form av metan. Att minska övergödningen är avgörande för att begränsa metanutsläppen och därmed motverka klimatförändringarna.

Flood dynamics are important drivers of wetland biodiversity. With current climate and land-use changes affecting overall water cycling, many wetland ecosystems are at risk of degradation, affecting biodiversity support negatively. This emphasizes a need for understanding possible correlations between specific hydrological conditions and biodiversity support in wetlands, at least in terms of species composition. In this study, we used high resolution hydrological monitoring of water levels and insect sampling in a depressional wetland to investigate possible correlations between inundation patterns and insect abundance. Our results show that there is a high spatial and temporal heterogeneity in wetland inundation patterns and that this heterogeneity explains variation in insect abundance. This creates episodes of downstream wet and upstream dry conditions. In addition, the spatial variability was high between grid cells of 2 meter’s resolution. There were also indications that distance to stream affected insect community structure. The findings from this work show that that the local hydrological conditions can create heterogeneity in habitat conditions, which in turn lead to refuge habitats for species vulnerable to changes in inundation condition. This study also highlights the importance of acknowledging quantitative hydrological methods when assessing the relation to insect communities.

The hidden presence of opportunistic bacterial pathogens in the environment evokes concerns about emerging diseases, especially in the light of climate change. The co-evolution of bacteria and their predators (protozoa) has led to bacterial defence strategies of which some contribute to the ability of bacteria to cause disease. To increase our understanding of the interplay between bacteria, protozoa, land use, and climate scenarios in Nordic brackish and freshwater, four studies were designed. The first study explored the co-occurrence patterns between predation resistant bacteria (PRB) and bacterivorous protozoa in a coastal area in the northern Baltic Sea. The results showed higher PRB diversity in the bays and freshwater inlets, than in the offshore waters. Further, genotype specific interactions between protozoa and bacteria were identified. The second study focused on Legionella species diversity and their association with humic substances and low salinity, potentially facilitated through the promotion of the heterotrophic microbial food web or by iron availability. The third study examined the impact of intensified land use on bacterial taxa abundance and community composition in lake inflows, demonstrating indirect downstream effects on water quality. Factors such as pastures, fields, farms, aluminium, iron, and humic substances were linked to increased Legionella abundance. The fourth study exposed aquatic organisms to climate change scenarios, causing eutrophication or brownification with elevated iron levels. Pseudomonas aeruginosa were found to be especially persistent to iron, likely linked to the same mechanism that enables survival in protozoan cells. This trait was shared with other observed intracellular pathogens and uncultured species, who showed elevated resilience to brownification and ability to survive outside host cells. These findings identified complex relationships, which improve our understanding of the intricate dynamics that shape aquat

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En stor del av de mänskligt orsakade utsläppen av koldioxid har tagits upp av haven. Men många av de svenska kusterna är idag påverkade av övergödning, vilket gör dem till en källa till växthusgaser, främst i form av metan. Att minska övergödningen är avgörande för att begränsa metanutsläppen och därmed motverka klimatförändringarna.

Lakes contribute 9%-19% of global methane (CH4) emissions to the atmosphere. Dissolved molecular oxygen (DO) in lakes can inhibit the production of CH4 and promote CH4 oxidation. DO is therefore often considered an important regulator of CH4 emissions from lakes. Presence or absence of DO in the water above the sediments can affect CH4 production and emissions by (a) influencing if methane production can be fueled by the most reactive organic matter in the top sediment layer or rely on deeper and less degradable organic matter, and (b) enabling CH4 accumulation in deep waters and potentially large emissions upon water column turnover. However, the relative importance of these two DO effects on CH4 fluxes is still unclear. We assessed CH4 fluxes from two connected lake basins in northern boreal Sweden where one was experimentally oxygenated. Results showed no clear difference in summer CH4 emissions attributable to water column DO concentrations. Large amounts of CH4 accumulated in the anoxic hypolimnion of the reference basin but little of this may have been emitted because of incomplete mixing, and effective methane oxidation of stored CH4 reaching oxic water layers. Accordingly, <= 24% of the stored CH4 was likely emitted in the experimental lake. Overall, our results suggest that hypolimnetic DO and water column CH4 storage might have a smaller impact on CH4 emissions in boreal forest lakes than previous estimates, yet potential fluxes associated with water column turnover events remain a significant uncertainty in lake CH4 emission estimates., Funding Agencies|European Research Council under the European Union [725546]; Knut and Alice Wallenberg Foundation [2016.0083]; Knut and Alice Wallenberg Foundation (Wallenberg Academy Fellowship); Swedish Research Council [2018-01794]

Headwater streams are often characterized by turbulence, organic matter inputs from terrestrial systems, net heterotrophy, and the microbial loop supplying carbon and energy for consumers. However, ecological models overlook dark carbon fixation (DCF), the light-independent inorganic carbon uptake, mainly based on chemosynthesis, using energy yields from redox reactions. The quantification of microbial biomass production, including DCF, heterotrophic production (HP), gross primary production (GPP), and ecosystem respiration (ER) in lotic aquatic systems, has long yet to be addressed. Here, we investigate HP and DCF in water, sediment, and litter in addition to GPP and ER from streams in pristine rainforests in three distinct sub-basins of the Amazon River, assessing the variety of turbid, black, and clear waters. We observed mean (min-max) values of microbial biomass production of about 0.1 (0.02-1.2), 3.2 (0.8-14.1), and 0.1 (0.02-0.5) mg C m-2 h-1 in water, sediment, and litter samples, in which DCF : HP showed mean (min-max) values of 0.5 (0.2-2), 0.02 (0.001-0.07), and 0.2 (0.001-0.5). Hence, measurements yielded DCF of similar magnitude as HP in water and litter but significantly lower in sediment, indicating that DCF supplied more carbon to planktonic and litter microbes than in top sediments of streams. Literature comparisons show similar DCF and GPP, both being lower than ER in streams. Finally, we found stream DCF higher than in lentic systems, suggesting that flow and turbulence may accelerate chemosynthesis., Funding Agencies|The research was supported by grants to FM-S (CNPq 152325/2020-4, CAPES 001, CAPES/STINT Brazil-Sweden 2012/2085). AE-P acknowledges funding from the Swedish Research Council Formas (grant no. 2021-02429) and several grants from Brazilian Foundations CAPES [CNPq 152325/2020-4, CAPES/STINT Brazil-Sweden 2012/2085]; Swedish Research Council Formas [2021-02429]; Brazilian Foundations CAPES; FAPERJ (Cientista do Nosso Estado); CNPq (Universal and Ciencias sem Fronteiras) [2012-00048]; Swedish Research Council VR; European Research Council ERC [725546 METLAKE]; Formas [2018-01794]; CNPq [203366/2019-0, 314995/2020-0]; FAPERJ [E-26/201.118/2022, E-26/210.441/2021]

The COVID-19 pandemic has affected all domains of human life, including the economic and social fabric of societies. One of the central strategies for managing public health throughout the pandemic has been through persuasive messaging and collective behaviour change. To help scholars better understand the social and moral psychology behind public health behaviour, we present a dataset comprising of 51,404 individuals from 69 countries. This dataset was collected for the International Collaboration on Social & Moral Psychology of COVID-19 project (ICSMP COVID-19). This social science survey invited participants around the world to complete a series of moral and psychological measures and public health attitudes about COVID-19 during an early phase of the COVID-19 pandemic (between April and June 2020). The survey included seven broad categories of questions: COVID-19 beliefs and compliance behaviours; identity and social attitudes; ideology; health and well-being; moral beliefs and motivation; personality traits; and demographic variables. We report both raw and cleaned data, along with all survey materials, data visualisations, and psychometric evaluations of key variables.

En stor del av de mänskligt orsakade utsläppen av koldioxid har tagits upp av haven. Men många av de svenska kusterna är idag påverkade av övergödning, vilket gör dem till en källa till växthusgaser, främst i form av metan. Att minska övergödningen är avgörande för att begränsa metanutsläppen och därmed motverka klimatförändringarna.

Groundwater depletion has become increasingly challenging, and many cities worldwide have adopted drastic policies to relieve water stress due to socioeconomic growth. Located on the declining aquifer of the North China Plain, Beijing, for example, has developed plans to limit the size of the city's population. However, the effect of population displacement under uncertain macroeconomic and climate change remains ambiguous. We adopt a sociohydrological model, with explicit consideration of the dynamics of human-water interactions, to explore the groundwater vulnerability of Beijing. We investigate how human response might shape the development trajectories of the groundwater-population-economy system under different macroscale economic and climate scenarios. Furthermore, we use a machine learning algorithm to identify the decisive factors to be considered for reducing groundwater vulnerability. Our results show that while rapid external economic development or larger annual average precipitation would enable recovery of the groundwater table in the short term, they may slacken human water shortage awareness and result in more acute groundwater depletion in the long run. Strengthening policymaker perceptions of groundwater depletion would prompt timely response policies for controlling population size. Improving the quantity and quality of labor force input to economic development would avoid downturns in the economy due to labor shortages. The outcomes of this study suggest that these strategies would effectively reduce groundwater vulnerability in the long run without causing severe socioeconomic recession. These findings highlight the importance of endogenizing human behavioral dynamics in sustainable urban water management. Beijing's groundwater vulnerability to external economic and climate change is assessed using a coupled sociohydro-economic modelRapid external economic development or larger precipitation might unintendedly lead to more severe groundwater dep

Seasonal deformation of mountain rock slopes can be driven by groundwater infiltration and depletion. Such processes could explain our field observation in the Aletsch Valley, Switzerland, where GNSS-derived 3D annual displacement amplitudes reach 3.4 cm. However, the physical mechanisms behind such groundwater-driven surface displacements are not well understood. Here, we develop a fully coupled hydromechanical model to simulate the relevant processes in a valley slope embedded with numerous fractures of variable sizes. The magnitude and orientation of transient annual slope surface displacement obtained from our model are in overall agreement with the field observations. The key geological factors controlling the type and magnitude of reversible mountain slope deformations are fracture network geometry, fracture aperture, and regional stress field. We show that the heterogeneity and anisotropy of bedrock hydromechanical responses, originating from depth-dependent variations of fracture properties, play a critical role in groundwater recharge and valley slope deformation. During recharge events, pore pressure perturbations migrate downward from the groundwater table and toward the receiving stream and the deep subsurface. This process driven by pressure diffusion and poroelastic stressing develops in the subsurface with a great reach of up to a few kilometers, called critical hydromechanical response zone, and controls surface deformation patterns. During groundwater recession, this hydromechanical response zone expands downward and ground surface displacement vectors rotate upwards. Our results suggest that slope surface deformation can inform about subsurface permeability structures and pore pressure fluctuations, which have important implications for understanding groundwater flow in fractured bedrock slopes.

Snow in the mountains is essential for the water cycle in cold regions. The complexity of the snow processes in such an environment makes it challenging for accurate snow and runoff predictions. Various snow modelling approaches have been developed, especially to improve snow predictions. In this study, we compared the ability to improve runoff predictions in the Överuman Catchment, Northern Sweden, using different parametric representations of snow distribution. They included a temperature-based method, a snowfall distribution (SF) function based on wind characteristics and a snow depletion curve (DC). Moreover, we assessed the benefit of using distributed snow observations in addition to runoff in the hydrological model calibration. We found that models with the SF function based on wind characteristics better predicted the snow water equivalent (SWE) close to the peak of accumulation than models without this function. For runoff predictions, models with the SF function and the DC showed good performances (median Nash–Sutcliffe efficiency equal to 0.71). Despite differences among the calibration criteria for the different snow process representations, snow observations in model calibration added values for SWE and runoff predictions.

Droughts are predicted to increase in both frequency and intensity by the end of the 21st century, but ecosystem response is not expected to be uniform across landscapes. Here we assess the importance of the hill-to-valley hydrologic gradient in shaping vegetation embolism resistance under different rainfall regimes using hydraulic functional traits. We demonstrate that rainfall and hydrology modulate together the embolism resistance of tree species in different sites and topographic positions. Although buffered by stable access to groundwater, valley plants are intrinsically more vulnerable to drought-induced embolism than those on hills. In all study sites, the variability in resistance to embolism is higher on hills than on valleys, suggesting that the diversity of strategies to cope with drought is more important for tree communities on hills. When comparing our results with previously published data across the tropics, we show greater variability at the local scale than previously reported. Our results reinforce the urgent need to extend sampling efforts across rainfall regimes and topographic positions to improve the characterization of ecosystem resistance to drought at finer spatial scales.

Insufficient in situ observations from the Antarctic marginal ice zone (MIZ) limit our understanding and description of relevant mechanical and thermodynamic processes that regulate the seasonal sea ice cycle. Here we present high-resolution thermal images of the ocean surface and complementary measurements of atmospheric variables that were acquired underway during one austral winter and one austral spring expedition in the Atlantic and Indian sectors of the Southern Ocean. Skin temperature data and ice cover images were used to estimate the partitioning of the heterogeneous surface and calculate the heat fluxes to compare with ERA5 reanalyses. The winter MIZ was composed of different but relatively regularly distributed sea ice types with sharp thermal gradients. The surface-weighted skin temperature compared well with the reanalyses due to a compensation of errors between the sea ice fraction and the ice floe temperature. These uncertainties determine the dominant source of inaccuracy for heat fluxes as computed from observed variables. In spring, the sea ice type distribution was more irregular, with alternation of sea ice cover and large open water fractions even 400 km from the ice edge. The skin temperature distribution was more homogeneous and did not produce substantial uncertainties in heat fluxes. The discrepancies relative to reanalysis data are however larger than in winter and are attributed to biases in the atmospheric variables, with the downward solar radiation being the most critical.

Ponds and "pondscapes" (networks of ponds) are crucial habitats for biodiversity and for delivering multiple benefits to humans, so-called "Nature's Contribution to People", such as climate mitigation and adaptation to climate change, creation, and maintenance of habitat for biodiversity, water purification, flood mitigation and cultural benefits (e.g., recreational possibilities). However, ponds are not often considered as Nature-based Solutions to provide all these benefits. In addition, there is insufficient knowledge on how to manage and restore ponds to maximise their role to increase the resilience of ecosystems and society to climate change. To facilitate improved implementation of ponds as Nature-based Solutions for the delivery of a wide range of Nature Contributions to People, it is important to generate and integrate biodiversity, ecosystems, societal, economic and policy knowledge. Hence, there is a need for evidence-based guidance to support the broader use of ponds. Here, we review the role of ponds and pondscapes in delivering Nature's Contributions to People and provide an overview of the challenges and opportunities for their broader implementation as Nature-based Solutions. Finally, we propose a conceptual framework that can help the implementation of pond Nature-based Solutions, and that outlines future research needs.

Cyanobacterial blooms have substantial direct and indirect negative impacts on freshwater ecosystems including releasing toxins, blocking light needed by other organisms, and depleting oxygen. There is growing concern over the potential for climate change to promote cyanobacterial blooms, as the positive effects of increasing lake surface temperature on cyanobacterial growth are well documented in the literature; however, there is increasing evidence that cyanobacterial blooms are also being initiated and persisting in relatively cold-water temperatures (< 15 °C), including ice-covered conditions. In this work, we provide evidence of freshwater cold-water cyanobacterial blooms, review abiotic drivers and physiological adaptations leading to these blooms, offer a typology of these lesser-studied cold-water cyanobacterial blooms, and discuss their occurrence under changing climate conditions.

In a changing climate, drought risk and vulnerability assessments are becoming increasingly important. Following the global call for proactive drought risk management, drought vulnerability assessments are progressively taking their stage in the drought research community. As the manifestation of drought vulnerability is dependent on the social, ecological, and hydroclimatic context in which it occurs, identifying vulnerability factors relevant for specific climatological and ecological regions may improve the quality of vulnerability assessments. Meanwhile, a holistic overview of factors affecting vulnerability in polar and cold climates is currently lacking. These regions are home to large socio-hydrological systems including urban areas, energy systems, agricultural practices, and the boreal forest. By conducting an interdisciplinary systematic literature review, the manifestation and conceptualization of drought vulnerability were identified for forested ecoregions in the Köppen–Geiger D and E climates. Vulnerability factors, as described by several scientific disciplines, were identified and combined into a conceptual framework for drought vulnerability in the study region. The results demonstrate the wide range of conceptualizations that exist for assessing drought vulnerability, and the thematic differences between sectors such as forestry, water supply, and agriculture. The conceptual framework presented herein adopts a novel approach, categorizing vulnerability factors by their location in a socio-hydrological system, and their relation to blue or green water sources. This allowed for identification of systemic vulnerability patterns, providing new insights into regional differences in drought vulnerability and a base for stakeholders performing proactive drought risk assessments in the study region.

The hidden presence of opportunistic bacterial pathogens in the environment evokes concerns about emerging diseases, especially in the light of climate change. The co-evolution of bacteria and their predators (protozoa) has led to bacterial defence strategies of which some contribute to the ability of bacteria to cause disease. To increase our understanding of the interplay between bacteria, protozoa, land use, and climate scenarios in Nordic brackish and freshwater, four studies were designed. The first study explored the co-occurrence patterns between predation resistant bacteria (PRB) and bacterivorous protozoa in a coastal area in the northern Baltic Sea. The results showed higher PRB diversity in the bays and freshwater inlets, than in the offshore waters. Further, genotype specific interactions between protozoa and bacteria were identified. The second study focused on Legionella species diversity and their association with humic substances and low salinity, potentially facilitated through the promotion of the heterotrophic microbial food web or by iron availability. The third study examined the impact of intensified land use on bacterial taxa abundance and community composition in lake inflows, demonstrating indirect downstream effects on water quality. Factors such as pastures, fields, farms, aluminium, iron, and humic substances were linked to increased Legionella abundance. The fourth study exposed aquatic organisms to climate change scenarios, causing eutrophication or brownification with elevated iron levels. Pseudomonas aeruginosa were found to be especially persistent to iron, likely linked to the same mechanism that enables survival in protozoan cells. This trait was shared with other observed intracellular pathogens and uncultured species, who showed elevated resilience to brownification and ability to survive outside host cells. These findings identified complex relationships, which improve our understanding of the intricate dynamics that shape aquat

Tidal marshes store large amounts of organic carbon in their soils. Field data quantifying soil organic carbon (SOC) stocks provide an important resource for researchers, natural resource managers, and policy-makers working towards the protection, restoration, and valuation of these ecosystems. We collated a global dataset of tidal marsh soil organic carbon (MarSOC) from 99 studies that includes location, soil depth, site name, dry bulk density, SOC, and/or soil organic matter (SOM). The MarSOC dataset includes 17,454 data points from 2,329 unique locations, and 29 countries. We generated a general transfer function for the conversion of SOM to SOC. Using this data we estimated a median (± median absolute deviation) value of 79.2 ± 38.1 Mg SOC ha−1 in the top 30 cm and 231 ± 134 Mg SOC ha−1 in the top 1 m of tidal marsh soils globally. This data can serve as a basis for future work, and may contribute to incorporation of tidal marsh ecosystems into climate change mitigation and adaptation strategies and policies.

In lakes, the rates of gross primary production (GPP), ecosystem respiration (R), and net ecosystem production (NEP) are often controlled by resource availability. Herein, we explore how catchment vs. within lake predictors of metabolism compare using data from 16 lakes spanning 39°N to 64°N, a range of inflowing streams, and trophic status. For each lake, we combined stream loads of dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) with lake DOC, TN, and TP concentrations and high frequency in situ monitoring of dissolved oxygen. We found that stream load stoichiometry indicated lake stoichiometry for C : N and C : P (r2 = 0.74 and r2 = 0.84, respectively), but not for N : P (r2 = 0.04). As we found a strong positive correlation between TN and TP, we only used TP in our statistical models. For the catchment model, GPP and R were best predicted by DOC load, TP load, and load N : P (R2 = 0.85 and R2 = 0.82, respectively). For the lake model, GPP and R were best predicted by TP concentrations (R2 = 0.86 and R2 = 0.67, respectively). The inclusion of N : P in the catchment model, but not the lake model, suggests that both N and P regulate metabolism and that organisms may be responding more strongly to catchment inputs than lake resources. Our models predicted NEP poorly, though it is unclear why. Overall, our work stresses the importance of characterizing lake catchment loads to predict metabolic rates, a result that may be particularly important in catchments experiencing changing hydrologic regimes related to global environmental change.

Despite their small spatial extent, fluvial ecosystems play a significant role in processing and transporting carbon in aquatic networks, which results in substantial emission of methane (CH4) into the atmosphere. For this reason, considerable effort has been put into identifying patterns and drivers of CH4 concentrations in streams and rivers and estimating fluxes to the atmosphere across broad spatial scales. However, progress toward these ends has been slow because of pronounced spatial and temporal variability of lotic CH4 concentrations and fluxes and by limited data availability across diverse habitats and physicochemical conditions. To address these challenges, we present a comprehensive database of CH4 concentrations and fluxes for fluvial ecosystems along with broadly relevant and concurrent physical and chemical data. The Global River Methane Database (GriMeDB; 10.6073/pasta/f48cdb77282598052349e969920356ef, Stanley et al., 2023) includes 24ĝ€¯024 records of CH4 concentration and 8205 flux measurements from 5029 unique sites derived from publications, reports, data repositories, unpublished data sets, and other outlets that became available between 1973 and 2021. Flux observations are reported as diffusive, ebullitive, and total CH4 fluxes, and GriMeDB also includes 17ĝ€¯655 and 8409 concurrent measurements of concentrations and 4444 and 1521 fluxes for carbon dioxide (CO2) and nitrous oxide (N2O), respectively. Most observations are date-specific (i.e., not site averages), and many are supported by data for 1 or more of 12 physicochemical variables and 6 site variables. Site variables include codes to characterize marginal channel types (e.g., springs, ditches) and/or the presence of human disturbance (e.g., point source inputs, upstream dams). Overall, observations in GRiMeDB encompass the broad range of the climatic, biological, and physical conditions that occur among world river basins, although some geographic gaps remain (arid regions, tropical regi

The most critical step for methylmercury (MeHg) bioaccumulation in aquatic food webs is phytoplankton uptake of dissolved MeHg. Dissolved organic matter (DOM) has been known to influence MeHg uptake, but the mechanisms have remained unclear. Here we show that the concentration of DOM-associated thiol functional groups (DOM-RSH) varies substantially across contrasting aquatic systems and dictates MeHg speciation and bioavailability to phytoplankton. Across our 20 study sites, DOM-RSH concentrations decrease 40-fold from terrestrial to marine environments whereas dissolved organic carbon (DOC), the typical proxy for MeHg binding sites in DOM, only has a 5-fold decrease. MeHg accumulation into phytoplankton is shown to be directly linked to the concentration of specific MeHg binding sites (DOM-RSH), rather than DOC. Therefore, MeHg bioavailability increases systematically across the terrestrial-marine aquatic continuum as the DOM-RSH concentration decreases. Our results strongly suggest that measuring DOM-RSH concentrations will improve empirical models in phytoplankton uptake studies and will form a refined basis for modeling MeHg incorporation in aquatic food webs under various environmental conditions.

Cyanobacterial blooms have substantial direct and indirect negative impacts on freshwater ecosystems including releasing toxins, blocking light needed by other organisms, and depleting oxygen. There is growing concern over the potential for climate change to promote cyanobacterial blooms, as the positive effects of increasing lake surface temperature on cyanobacterial growth are well documented in the literature; however, there is increasing evidence that cyanobacterial blooms are also being initiated and persisting in relatively cold-water temperatures (< 15 °C), including ice-covered conditions. In this work, we provide evidence of freshwater cold-water cyanobacterial blooms, review abiotic drivers and physiological adaptations leading to these blooms, offer a typology of these lesser-studied cold-water cyanobacterial blooms, and discuss their occurrence under changing climate conditions.

Seasonal deformation of mountain rock slopes can be driven by groundwater infiltration and depletion. Such processes could explain our field observation in the Aletsch Valley, Switzerland, where GNSS-derived 3D annual displacement amplitudes reach 3.4 cm. However, the physical mechanisms behind such groundwater-driven surface displacements are not well understood. Here, we develop a fully coupled hydromechanical model to simulate the relevant processes in a valley slope embedded with numerous fractures of variable sizes. The magnitude and orientation of transient annual slope surface displacement obtained from our model are in overall agreement with the field observations. The key geological factors controlling the type and magnitude of reversible mountain slope deformations are fracture network geometry, fracture aperture, and regional stress field. We show that the heterogeneity and anisotropy of bedrock hydromechanical responses, originating from depth-dependent variations of fracture properties, play a critical role in groundwater recharge and valley slope deformation. During recharge events, pore pressure perturbations migrate downward from the groundwater table and toward the receiving stream and the deep subsurface. This process driven by pressure diffusion and poroelastic stressing develops in the subsurface with a great reach of up to a few kilometers, called critical hydromechanical response zone, and controls surface deformation patterns. During groundwater recession, this hydromechanical response zone expands downward and ground surface displacement vectors rotate upwards. Our results suggest that slope surface deformation can inform about subsurface permeability structures and pore pressure fluctuations, which have important implications for understanding groundwater flow in fractured bedrock slopes.

Droughts are predicted to increase in both frequency and intensity by the end of the 21st century, but ecosystem response is not expected to be uniform across landscapes. Here we assess the importance of the hill-to-valley hydrologic gradient in shaping vegetation embolism resistance under different rainfall regimes using hydraulic functional traits. We demonstrate that rainfall and hydrology modulate together the embolism resistance of tree species in different sites and topographic positions. Although buffered by stable access to groundwater, valley plants are intrinsically more vulnerable to drought-induced embolism than those on hills. In all study sites, the variability in resistance to embolism is higher on hills than on valleys, suggesting that the diversity of strategies to cope with drought is more important for tree communities on hills. When comparing our results with previously published data across the tropics, we show greater variability at the local scale than previously reported. Our results reinforce the urgent need to extend sampling efforts across rainfall regimes and topographic positions to improve the characterization of ecosystem resistance to drought at finer spatial scales.

Insufficient in situ observations from the Antarctic marginal ice zone (MIZ) limit our understanding and description of relevant mechanical and thermodynamic processes that regulate the seasonal sea ice cycle. Here we present high-resolution thermal images of the ocean surface and complementary measurements of atmospheric variables that were acquired underway during one austral winter and one austral spring expedition in the Atlantic and Indian sectors of the Southern Ocean. Skin temperature data and ice cover images were used to estimate the partitioning of the heterogeneous surface and calculate the heat fluxes to compare with ERA5 reanalyses. The winter MIZ was composed of different but relatively regularly distributed sea ice types with sharp thermal gradients. The surface-weighted skin temperature compared well with the reanalyses due to a compensation of errors between the sea ice fraction and the ice floe temperature. These uncertainties determine the dominant source of inaccuracy for heat fluxes as computed from observed variables. In spring, the sea ice type distribution was more irregular, with alternation of sea ice cover and large open water fractions even 400 km from the ice edge. The skin temperature distribution was more homogeneous and did not produce substantial uncertainties in heat fluxes. The discrepancies relative to reanalysis data are however larger than in winter and are attributed to biases in the atmospheric variables, with the downward solar radiation being the most critical.

Sammanfattning Temperaturen i ytvattnet (0-10 m) var över det normala flera månader under 2022,temperaturer under det normala uppmättes endast vid några få tillfällen på sommaren.Dessa köldknäppar orsakades av uppvällning. Årets lägsta temperaturer i ytvattnetnåddes i mars i Skagerrak, vilket är en månad senare än normalt. I Kattegatt uppmättesden lägsta temperaturen i januari och i mars i Egentliga Östersjön. Temperaturer över det normala uppmättes även i de djupa och intermediära vattnen iEgentliga Östersjön. I Egentliga Östersjön visar temperaturen i djupvattnen en ökandetrend. Issäsongen klassificerades som mild men varaktigheten var längre än normalt. Denförsta isen observerades runt den 25 oktober och den sista isen den 2 juni. Närsaltskarteringarna på vintern visade att halterna av löst oorganiskt kväve var underde normala. Kisel och fosfat var över det normala i Bottenviken. Det senare stämmeröverens med en trend med ökande fosfat- och silikatkoncentrationer i Bottenviken. Näringsämnena minskar på våren när vårblomningen startar, 2022 skedde detta i mars iKattegatt och i april i Skagerrak. I Egentliga Östersjön inträffade vårblomningen mellanfebruari- och marsexpeditionerna i de södra delarna av havsområdet medan den varungefär en månad senare i bassängerna runt Gotland. I Bottenhavet saknas näringsdataför den period då vårblomningen inträffade. Men artsammansättningen och biomassaifrån växtplanktonmätningar visar att vårblomningen inträffade i april. I Bottenvikensjönk oorganiskt kväve till nivåer nära detektionsgränsen i juli. Den potentiellt giftiga dinoflagellaten Dinophysis acuta observerades i cellantal övervarningsgränsen under hösten stationerna på Västkusten. Det största området med cyanobakterieansamlingar observerades med satellit den 28juni då cirka 83 300 km2av Egentliga Östersjön och Finska Viken påverkades. Inga inflöden inträffade under 2022 som var tillräckligt stora för att påverka djupvattneti centrala Östersjön och därför fortsätter de pr, Summary The temperature in surface layer was above normal in several months during 2022,temperatures below normal were measured only on a few occasions in the summer.These occasions were caused by upwelling events. The minimum temperatures in thesurface layer in 2022 were reached in March in Skagerrak, which is a month later thannormal. In Kattegat the temperature reached its minimum in January and in March inthe Baltic Proper. Temperatures above normal were measured in the deep and intermediate waters in theBaltic Proper. In the Baltic Proper the temperature in the deep waters show anincreasing trend. The ice season was classified as mild but the duration was longer than normal, with thefirst ice observations around 25th of October and the last ice seen on 2nd of June. The nutrient surveys in winter showed that the concentrations of dissolved inorganicnitrogen were below normal, whereas silicate and phosphate were above normal in theBothnian Bay. The latter is consistent with a trend of increasing phosphate and silicateconcentration in the Bothnian Bay. The nutrients decreased in spring as the springbloom started, in 2022 this happened in March in Kattegat and in April in Skagerrak,which is later than normal. In the Baltic Proper it occurred between the February andMarch cruises in the southern parts while it started about a month later in the basinsaround Gotland. In the Bothnian Sea we lack nutrient data for the period when thespring bloom occurred, but phytoplankton data shows that the spring bloom occurred inApril. In the Bothnian Bay inorganic nitrogen dropped to levels near the detection limitin July. The potentially toxic dinoflagellate Dinophysis acuta was found in cell numbers abovethe warning limit during autumn at the stations situated in Skagerrak and Kattegat. The largest area of cyanobacteria surface accumulations was observed by satellite onthe 28th of June when about 83 300 km2 of the Baltic Proper and Gulf of Finland wereaffected. No new inflows oc

Växtplanktondata från provtagningar under perioden 1986–2021 längs Västra Götalands kust (Bohuskusten och Göteborgs skärgård) har analyserats. Fokus har varit åtta stationer som har tidsserier från 1991–2021 med provtagningar året om. Data från andra stationer har också använts. När det gäller klorofyll samt fysiska och kemiska parametrar finns ett större datamaterial med provtagningar på 14 stationer. En station i centrala Skagerrak har använts för jämförelser. Resultat från mikroskopanalys av prover visar på en relativt hög biodiversitet. Antal identifierade släkten är 195 och antalet arter är stort. Högst antal arter observeras under hösten, troligen som en effekt av transport av vatten från Nordsjön till Bohuskusten. Under den undersökta perioden har antal observerade släkten ökat. Om detta beror på en verklig ökning av biodiversiteten, t.ex. att arter som trivs i hög temperatur kommit till eller på andra faktorer, t.ex. att skickligheten hos de som analyserar prover ökat, går inte att utläsa från materialet. Strukturen på växtplanktonsamhället varierar under året och geografiskt. Havstensfjorden har en högre andel dinoflagellater jämfört med de flesta andra stationer. Flera arter som är nya för området har observerats, bl.a. Alexandrium pseudogonyaulax, Chaetoceros cf. peruvianus, Pseudosolenia calcar-avis och Dinophysis tripos. Växtplanktonbiomassan mätt som klorofyll a (0–10 m djup) har minskat i Koljöfjord, Havstensfjord, Byfjorden och vid Galterö (Stenungsund) under perioden 1991–2021 när man tittar på årsmedelvärden. Det gäller även om enbart värden från sommaren används. Då noteras även en minskning vid Stretudden (Brofjorden), vid Valö (Askimsfjorden) och station Å17 (öppna Skagerrak). Siktdjupet har ökat på flera platser sommartid: vid Byttelocket (Smögen), Stretudden (Brofjorden), Släggö (Gullmarsfjorden) och i Koljöfjorden. Koncentrationer under vintern av löst oorganiskt kväve (DIN = summan av nitrat, nitrit och ammonium) har minskat i ytvattnet på d

Ponds and "pondscapes" (networks of ponds) are crucial habitats for biodiversity and for delivering multiple benefits to humans, so-called "Nature's Contribution to People", such as climate mitigation and adaptation to climate change, creation, and maintenance of habitat for biodiversity, water purification, flood mitigation and cultural benefits (e.g., recreational possibilities). However, ponds are not often considered as Nature-based Solutions to provide all these benefits. In addition, there is insufficient knowledge on how to manage and restore ponds to maximise their role to increase the resilience of ecosystems and society to climate change. To facilitate improved implementation of ponds as Nature-based Solutions for the delivery of a wide range of Nature Contributions to People, it is important to generate and integrate biodiversity, ecosystems, societal, economic and policy knowledge. Hence, there is a need for evidence-based guidance to support the broader use of ponds. Here, we review the role of ponds and pondscapes in delivering Nature's Contributions to People and provide an overview of the challenges and opportunities for their broader implementation as Nature-based Solutions. Finally, we propose a conceptual framework that can help the implementation of pond Nature-based Solutions, and that outlines future research needs.

Cyanobacterial blooms have substantial direct and indirect negative impacts on freshwater ecosystems including releasing toxins, blocking light needed by other organisms, and depleting oxygen. There is growing concern over the potential for climate change to promote cyanobacterial blooms, as the positive effects of increasing lake surface temperature on cyanobacterial growth are well documented in the literature; however, there is increasing evidence that cyanobacterial blooms are also being initiated and persisting in relatively cold-water temperatures (< 15 °C), including ice-covered conditions. In this work, we provide evidence of freshwater cold-water cyanobacterial blooms, review abiotic drivers and physiological adaptations leading to these blooms, offer a typology of these lesser-studied cold-water cyanobacterial blooms, and discuss their occurrence under changing climate conditions.

In a changing climate, drought risk and vulnerability assessments are becoming increasingly important. Following the global call for proactive drought risk management, drought vulnerability assessments are progressively taking their stage in the drought research community. As the manifestation of drought vulnerability is dependent on the social, ecological, and hydroclimatic context in which it occurs, identifying vulnerability factors relevant for specific climatological and ecological regions may improve the quality of vulnerability assessments. Meanwhile, a holistic overview of factors affecting vulnerability in polar and cold climates is currently lacking. These regions are home to large socio-hydrological systems including urban areas, energy systems, agricultural practices, and the boreal forest. By conducting an interdisciplinary systematic literature review, the manifestation and conceptualization of drought vulnerability were identified for forested ecoregions in the Köppen–Geiger D and E climates. Vulnerability factors, as described by several scientific disciplines, were identified and combined into a conceptual framework for drought vulnerability in the study region. The results demonstrate the wide range of conceptualizations that exist for assessing drought vulnerability, and the thematic differences between sectors such as forestry, water supply, and agriculture. The conceptual framework presented herein adopts a novel approach, categorizing vulnerability factors by their location in a socio-hydrological system, and their relation to blue or green water sources. This allowed for identification of systemic vulnerability patterns, providing new insights into regional differences in drought vulnerability and a base for stakeholders performing proactive drought risk assessments in the study region.

Snow in the mountains is essential for the water cycle in cold regions. The complexity of the snow processes in such an environment makes it challenging for accurate snow and runoff predictions. Various snow modelling approaches have been developed, especially to improve snow predictions. In this study, we compared the ability to improve runoff predictions in the Överuman Catchment, Northern Sweden, using different parametric representations of snow distribution. They included a temperature-based method, a snowfall distribution (SF) function based on wind characteristics and a snow depletion curve (DC). Moreover, we assessed the benefit of using distributed snow observations in addition to runoff in the hydrological model calibration. We found that models with the SF function based on wind characteristics better predicted the snow water equivalent (SWE) close to the peak of accumulation than models without this function. For runoff predictions, models with the SF function and the DC showed good performances (median Nash–Sutcliffe efficiency equal to 0.71). Despite differences among the calibration criteria for the different snow process representations, snow observations in model calibration added values for SWE and runoff predictions.

River deltas and lakes support biodiversity and offer crucial ecosystem services such as freshwater provision, flood control, and fishing. However, climate change and human activities have affected deltas and lakes globally, altering the services they provide. Since delta and lake surface water occurrence and water levels respond to climate change and anthropogenic activities, we need to monitor their variations to understand the potential drivers for effective water management strategies. However, important deltas like the Selenga River Delta (SRD) in Russia lack a detailed analysis of water occurrence. Regarding lake water level, there has been a decline in the number of gauging stations globally, due to installation and maintenance costs. For example, Sweden has ~100,000 lakes which are sources of freshwater and hydro-power, but only 38 lakes have long and continuous in-situ records of water level. As satellite data are reliable alternatives for conventional methods to monitor deltas and lakes, I employed Earth Observations (EO) to quantify changes in surface water occurrence in the SRD and water levels in Swedish lakes and identify their main drivers. I also developed and explored a novel methodology for lake water level estimation based on Differential Interferometric Synthetic Aperture Radar (D-InSAR) by calculating the six-day phase differences in 30 Swedish lakes. To achieve these objectives, I trained and applied a Maximum Likelihood classification to Landsat images from 1987 to 2020 and quantified surface water occurrence and its changes in the SRD. I found that surface water occurrence in 51% of the delta experienced a decrease. As the Selenga River is the only river flowing into the SRD, the change in surface water occurrence in the SRD correlated with river discharge, but not with the river suspended sediment concentration, the lake water level in the outlet of the SRD, or evapotranspiration over the delta. In Sweden, I used satellite altimetry data fro, Floddeltan och sjöar stöder den biologiska mångfalden och erbjuder viktiga ekosystemtjänster som färskvattenförsörjning, översvämningsbekämpning och fiske. Klimatförändringar och mänskliga aktiviteter har dock påverkat deltan och sjöar globalt och förändrat de tjänster de tillhandahåller. Eftersom förekomsten av ytvatten i delta och sjöar och vattennivåerna svarar på klimatförändringar och antropogena aktiviteter måste vi övervaka deras variationer för att förstå de potentiella drivkrafterna för effektiva vattenförvaltningsstrategier. Viktiga deltan som Selenga River Delta (SRD) i Ryssland saknar dock en detaljerad analys av vattenförekomsten. När det gäller sjöarnas vattennivå har antalet mätstationer minskat på grund av installations- och underhållskostnader. Till exempel har Sverige ~ 100 000 sjöar som är källor till sötvatten och vattenkraft, men endast 38 sjöar har långa och kontinuerliga in situ-register över vattennivån. Eftersom satellitdata är tillförlitliga alternativ till konventionella metoder för att övervaka deltan och sjöar, har jag använt satellitobservationer för att kvantifiera förändringar i ytvattenförekomst i SRD och vattennivåer i svenska sjöar och identifiera deras huvudsakliga drivkrafter. Jag har vidare utvecklat och utforskat en ny metod för uppskattning av sjövattennivån baserad på Differential Interferometric Synthetic Aperture Radar (D-InSAR) genom att beräkna sexdagars fasskillnader i 30 svenska sjöar. För att uppnå dessa mål har jag övat på, samt tillämpat en Maximum Likelihood-klassificering på Landsat-bilder från 1987 till 2020 och kvantifierade ytvattenförekomst och dess förändringar i SRD. Jag har nått slutsatsen att ytvattenförekomsten i 51 % av deltat upplevt en minskning. Eftersom Selengafloden är den enda flod som rinner ut i SRD, korrelerade förändringen i ytvattenförekomsten i SRD med flodutsläpp, men inte med flodens suspenderade sedimentkoncentration, sjövattennivån i SRD:s utlopp eller evapotranspiration över deltat. I Sve

Wetlands provide ecosystem services valuable for human society and are therefore often considered as nature based solution to different environmental problems. However, with centuries of wetland degradation due to anthropogenic pressures, such as agricultural expansion and forest industry, as well as pressures from climate change, there are large challenges for sustainable wetland management. Thus, for wetland protection and restoration practices to be successful, a deepened understanding on the actual mechanisms controlling wetland functions is required. Understanding how wetlands are connected, with and influenced, by their surrounding environment is also needed. Although most pressures experienced by wetlands operate on scales beyond the individual wetland scale, relatively few studies have thus far addressed large-scale functions and ecosystem service provision from hydrologically interconnected wetlands at the scale of wetlandscapes (i.e., the wetlands’ aggregated hydrological catchments in the landscape). The aim of this thesis is to investigate ecosystem service delivery from wetlands and wetlandscapes under hydro-climatic changes, considering 25 different wetlandscapes located in four different climate zones of the world. The thesis also systematically quantifies ecohydrological characteristics important for ecosystem service delivery and biodiversity support of wetlands and wetlandscapes in the Norrström Drainage basin located near Stockholm, Sweden. Conducted hydro-climatic analyses showed that impacts of climate change on wetlandscapes cannot be fully understood from average changes in climatic variables of the climate zones within which the wetlandscapes are located. This may be due to the fact that wetlands are not randomly and evenly distributed within climate zones, but may be located in areas subject to stronger climatic changes than regional means. In addition, anthropogenic pressures were on average shown to have higher impacts on runoff in wetlan

Flood dynamics are important drivers of wetland biodiversity. With current climate and land-use changes affecting overall water cycling, many wetland ecosystems are at risk of degradation, affecting biodiversity support negatively. This emphasizes a need for understanding possible correlations between specific hydrological conditions and biodiversity support in wetlands, at least in terms of species composition. In this study, we used high resolution hydrological monitoring of water levels and insect sampling in a depressional wetland to investigate possible correlations between inundation patterns and insect abundance. Our results show that there is a high spatial and temporal heterogeneity in wetland inundation patterns and that this heterogeneity explains variation in insect abundance. This creates episodes of downstream wet and upstream dry conditions. In addition, the spatial variability was high between grid cells of 2 meter’s resolution. There were also indications that distance to stream affected insect community structure. The findings from this work show that that the local hydrological conditions can create heterogeneity in habitat conditions, which in turn lead to refuge habitats for species vulnerable to changes in inundation condition. This study also highlights the importance of acknowledging quantitative hydrological methods when assessing the relation to insect communities.

Hydrological climate-change-impact studies depend on climatic variables simulated by climate models. Due to parametrization and numerous simplifications, however, climate-model outputs come with systematic biases compared to the observations. In the past decade, several methods of different complexity and dimensionality for adjustment of such biases were introduced, but their benefits for impact studies and accurate streamflow pro-jections are still debated. In this paper, we evaluated the ability of two state-of-the-art, advanced multivariate bias-adjustment methods to accurately reproduce 16 hydrological signatures, and compared their performance against two parsimonious univariate bias-adjustment methods based on a multi-criteria performance evaluation. The results indicated that all bias-adjustment methods considerably reduced biases and increased the consistency of simulated hydrological signatures. The added value of multivariate methods in maintaining dependence structures between precipitation and temperature was not systematically reflected in the resulting hydrological signatures, as they were generally outperformed by univariate methods. The benefits of multivariate methods only emerged for low-flow signatures in snowmelt-driven catchments. Based on these findings, we identified the most suitable bias-adjustment methods for water-resources management in Nordic regions under a changing climate, and provided practical guidelines for the selection of bias-adjustment methods given specific research targets and hydroclimatic regimes.

This work presents a methodology for the Large-Eddy Simulation (LES) of the continuous transition of atmospheric stability over forests along the diurnal cycle and its effect on the turbulence characteristics of wind turbine wakes. The forest is modelled as a porous surface where temperature changes, transferred to the air via sensible transport, are caused by the variation of net radiation and in proportion to the tree height and leaf density. The flow is driven by a pressure gradient including Coriolis forcing to allow for the development of nocturnal inertial oscillations. An actuator disk is employed to model the wake of a wind turbine located in Ryningsnas, Sweden, for which metmast measurements are available to carry out a comparison. Results show a good prediction of the inflow and wake characteristics during daytime whereas turbulence fluctuations seem to be overestimated during night periods, attributed to a combination of an excess in geostrophic velocity and coarse mesh resolution. Observations of velocity, heat flux, potential temperature, velocity spectra and other higher order statistics are used to characterize the diurnal variations both in the inflow and across the wake. The results show that the model is capable of representing the turbulence flow dynamics during the diurnal stability transition, hence laying the ground to future studies to assess the performance of wind parks over forested areas.