Sarian Kosten

Radboud University | RU · Department of Aquatic Ecology and Environmental Biology

Aquaculture is increasing globally, providing protein to a growing population, but little is known regarding the nutrient budgets in aquaculture. To obtain insight into how management practices impact nutrient fluxes in freshwater aquaculture earthen ponds worldwide, we conducted a literature review. Our literature search yielded 23 papers in which...

Effecten van natuurherstel op de broeikasgasbalans van natuurgebieden-Een eerste stap richting kengetallen samen werken aan natuurherstel

The national effort on climate adaptation and mitigation is demanding more and more from water and nature management. In recent decades research has increasingly focused on this topic on a national and international scale, but the issues remain complex. Knowledge about water quantity, water quality and water management is essential to understand ef...

Rivers and streams contribute to global carbon cycling by decomposing immense quantities of terrestrial plant matter. However, decomposition rates are highly variable, and large-scale patterns and drivers of this process remain poorly understood. Using a cellulose-based assay to reflect the primary constituent of plant detritus, we generated a pred...

Benthic primary producers (BPP) in inland waters, including aquatic macrophytes and periphyton, are foundational habitats that are highly sensitive to multiple human drivers of environmental change. However, long‐term seasonal monitoring of BPP is limited, leaving us with little information on the cause, directionality, and consequences of the pote...

Lakes and ponds experience anthropogenically forced changes that may be non-linear and sometimes initiate ecosystem feedbacks leading to tipping points beyond which impacts become hard to reverse. In many cases climate change is a key driver, sometimes in concert with other stressors. Lakes are also important players in the global climate by ventil...

A growing body of literature points to drawdown areas as important sources of atmospheric CO2 within reservoirs. Yet seasonal and temporal patterns of CO2 flux from periodically exposed sediments in drawdown areas remain poorly understood. Here we evaluate the annual and diel (24-hour cycle) variations in CO2 emissions from sediments periodically e...

Aquatic ecosystems are large contributors to global methane (CH4) emissions. Eutrophication significantly enhances CH4-production as it stimulates methanogenesis. Mitigation measures aimed at reducing eutrophication, such as the addition of metal salts to immobilize phosphate (PO43−), are now common practice. However, the effects of such remedies o...

Freshwater ecosystems, including lakes, wetlands, and running waters, are estimated to contribute over half the natural emissions of methane (CH4) globally, yet large uncertainties remain in the inland water CH4 budget. These are related to the highly heterogeneous nature and the complex regulation of the CH4 emission pathways, which involve diffus...

Greenhouse gas (GHG) emissions from drained peatlands have been studied extensively. Considerably less attention has been paid to the emissions from the ditches used to drain peatlands. High within‐ditch GHG production and lateral inflow of GHGs may lead to ditches emitting considerable amounts of GHGs on the landscape scale. We quantified annual e...

An ever-increasing demand for protein-rich food sources combined with dwindling wild fish stocks has caused the aquaculture sector to boom in the last two decades. Although fishponds are potentially strong emitters of the greenhouse gas methane (CH 4 ), little is known about the magnitude, pathways, and drivers of these emissions. We measured diffu...

Dredging, the removal of sediment from water courses, is generally conducted to maintain their navigability and to improve water quality. Recent studies indicate that dredging can significantly reduce aquatic greenhouse gas (GHG) emissions. These studies, however, do not consider the potential emission from the dredged material (sludge) in the depo...

Lakes experience anthropogenically-forced changes that may initiate ecosystem feedbacks, in some cases reaching tipping points beyond which impacts become hard to reverse. Lakes are also important players in the global climate by ventilating a large share of terrestrial carbon back to the atmosphere as greenhouse gases, and will likely provide subs...

Unravelling patterns and mechanisms of biogeographical transitions is crucial if we are to understand compositional gradients at large spatial extents, but no studies have thus far examined breakpoints in community composition of freshwater plants across continents. Using a dataset of almost 500 observations of lake plant community composition from...

In agricultural landscapes of North-Western Europe, the majority of water bodies do not meet the targets set by the European Water Framework Directive due to a lack of submerged macrophytes and associated biodiversity. These eutrophic waters can also be a substantial source of methane (CH4) and carbon dioxide (CO2) to the at- mosphere. Here we pres...

Greenhouse gas (GHG) emissions from small inland waters are disproportionately large. Climate warming is expected to favour dominance of algae and free-floating plants at the expense of submerged plants. Through different routes these functional plant types may have far-reaching impacts on freshwater GHG emissions in future warmer waters, which are...

Wetlands are large sources of methane (CH4), and plant-mediated fluxes can contribute considerably to their total CH4 emissions. However, plant-mediated fluxes vary considerably even within species, and the factors explaining this variation are not fully understood. This study focuses on the role of plant traits and environmental conditions in regu...

NON FORMATED PUBLISHED VERSION Feedbacks between climate change and eutrophication: revisiting the allied attack concept and how to strike back Despite its well-established negative impacts on society and biodiversity, eutrophication continues to be one of the most pervasive anthropogenic influence along the freshwater to marine continuum. The i...

Freshwater ecosystems are an important source of the greenhouse gas methane (CH4), and their emissions are expected to increase due to eutrophication. Two commonly applied management techniques to reduce eutrophication are the addition of phosphate-binding lanthanum modified bentonite (LMB, trademark Phoslock©) and dredging, but their effect on CH4...

Severe eutrophication threatens freshwater systems around the world. The application of aquatic buffer zones with plants, for example around agricultural lands, can increase nutrient retention and thereby reduce nutrient loading to downstream systems. However, not much is known about greenhouse gas (GHG) emissions from these buffer zones and how th...

Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low‐nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing clima...

Despite its well-established negative impacts on society and biodiversity, eutrophication continues to be one of the most pervasive anthropogenic influence along the freshwater to marine continuum. The interaction between eutrophication and climate change, particularly climate warming, was explicitly focused upon a decade ago in the paper by Moss e...

To investigate the potential long-term consequences of environmental warming in subtropical systems, we compare the trophic structure of shallow lakes in tropical and subtropical regions. In total, 25 meso-eutrophic lakes with piscivorous fish were sampled during summer along a latitudinal gradient in South America. The fish catch per unit of effor...

Body size is usually considered a good indicator of trophic position in fish communities. Indeed, the proverbial wisdom that “Big Fish Eat Little Fish” is consistent with observations from marine systems where systematic removal of the largest individuals has occurred, with cascading effect in the ecosystems. Trophic cascades are also well document...

Freshwater ecosystems, including wetlands, lakes, and running waters, are estimated to contribute roughly 40% to global emissions of methane (CH4), a highly potent greenhouse gas. The emission of CH4 to the atmosphere entails the diffusive, ebullitive, and plant-mediated pathway. The latter, in particular, has been largely understudied and is neith...

Fluxes of carbon dioxide (CO2) and methane (CH4) in shallow lakes are strongly affected by dominant primary producers which mostly has been studied in temperate and boreal regions. We compared summer CO2 and CH4 fluxes (diffusion and ebullition) in littoral and pelagic zones of three subtropical shallow lakes with contrasting regimes: clear-vegetat...

Despite substantial advances in quantifying greenhouse gas (GHG) emissions from dry inland waters, existing estimates mainly consist of carbon dioxide (CO2) emissions. However, methane (CH4) may also be relevant due to its higher Global Warming Potential (GWP). We report CH4 emissions from dry inland water sediments to i) provide a cross-continenta...

River plastic pollution is an environmental challenge of growing concern. However, there are still many unknowns related to the principal drivers of river plastic transport. Floating aquatic vegetation, such as water hyacinths, have been found to aggregate and carry large amounts of plastic debris in tropical river systems. Monitoring the entrapmen...

• Shallow aquatic systems exchange large amounts of carbon dioxide (CO2) and methane (CH4) with the atmosphere. The production and consumption of both gases is determined by the interplay between abiotic (such as oxygen availability) and biotic (such as community structure and trophic interactions) factors. • Fish communities play a key role in dri...

Water hyacinth is able to sequester large amounts of carbon dioxide (CO2) in wetlands. At the same time, the high production of organic matter combined with the plant’s capacity to limit the diffusion of oxygen from the atmosphere into the water creates favorable conditions for the production of methane (CH4). The combination of these mechanisms ch...

River plastic pollution is an environmental challenge of growing concern. However, there are still many unknowns related to the principal drivers of river plastic transport. Floating aquatic vegetation, such as water hyacinths, have been found to aggregate and carry large amounts of plastic debris in tropical river systems. Monitoring the entrapmen...

The restoration of degraded ecosystems and landscapes is challenging, because returning to the original state is often socio-economically unfeasible. A novel approach is to construct new ecosystems to improve the functioning of degraded landscapes. However, the development of novel ecosystems is largely driven by the pre-construction hydrogeophysic...

Globally, there are millions of kilometres of drainage ditches which have the potential to emit the powerful greenhouse gas methane (CH4), but these emissions are not reported in budgets of inland waters or drained lands. Here, we synthesise data to show that ditches spanning a global latitudinal gradient and across different land uses emit large q...

Regime shifts in inland waters are strong, abrupt, persistent changes in the structure and functioning of a system. Regime shifts typically describe transitions between contrasting ecological states. For instance, the shift from a clear lake, dominated by submerged vegetation, to a turbid, phytoplankton-dominated lake is a regime shift. In this cha...

Water hyacinth is able to sequester large amounts of carbon dioxide (CO 2) in wetlands. At the same time, the high production of organic matter combined with the plant's capacity to limit the diffusion of oxygen from the atmosphere into the water creates favorable conditions for the production of methane (CH 4). The combination of these mechanisms...

Documenting the patterns of biological diversity on Earth has always been a central challenge in macroecology and biogeography. However, we are only beginning to generate an understanding of the global patterns and determinants of macrophyte diversity. Here, we studied large-scale variation and community-environment relationships of lake macrophyte...

The widespread wetland species Phragmites australis (Cav.) Trin. ex Steud. has the ability to transport gases through its stems via a pressurized flow. This results in a high oxygen (O2) transport to the rhizosphere, suppressing methane (CH4) production and stimulating CH4 oxidation. Simultaneously CH4 is transported in the opposite direction to th...

While providing protein for a fast-growing human population, the ongoing boom in global aquaculture comes with environmental costs. Particularly, the intense greenhouse gas (GHG) emissions reported for several aquaculture systems are a source of concern. Still, we argue that actual emissions could be multiple times higher than currently thought. Mo...

• Shallow lakes can shift between stable states as a result of anthropogenic or natural drivers. Four common stable states differ in dominant groups of primary producers: submerged, floating, or emergent macrophytes or phytoplankton. Shifts in primary producer dominance affect key supporting, provisioning, regulating, and cultural ecosystem service...

Viruses are important drivers in the cycling of carbon and nutrients in aquatic ecosystems. Since viruses are obligate parasites, their production completely depends on growth and metabolism of hosts and therefore can be affected by climate change. Here, we investigated if warming (+4°C) can change the outcome of viral infections in a natural fresh...

Many inland waters exhibit complete or partial desiccation, or have vanished due to global change, exposing sediments to the atmosphere. Yet, data on carbon dioxide (CO 2) emissions from these sediments are too scarce to upscale emissions for global estimates or to understand their fundamental drivers. Here, we present the results of a global surve...

Water authorities responsible for water quantity and water quality management may strongly influence the magnitude of greenhouse gas emissions from the surface waters and the adjacent peat areas within their territories. Climate smart water management (reducing influx of organic matter and improving water quality) is therefore a potentially strong...

Increased periods of prolonged droughts followed by severe precipitation events are expected throughout South America due to climate change. Freshwater sediments are especially sensitive to these changing climate conditions. The increased oscillation of water levels in aquatic ecosystems causes enhanced cycles of sediment drying and rewetting. Here...

The future of formerly brackish peatlands: effects of salinization The last decades, Dutch former brackish peatlands have been heavily influenced by fresh surface water. The decrease in salinity led to a decrease of brackish water dependent species and Natura 2000 habitat types. Resalinization is currently considered. The present article summarizes...

Documenting the patterns of biological diversity on Earth has always been a central challenge in macroecology and biogeography. However, for the diverse group of freshwater plants, such research program is still in its infancy. Here, we examined global variation in taxonomic, functional and phylogenetic beta diversity patterns of lake macrophytes u...

Water hyacinth (WH), a large floating plant, plays an important role in the biogeochemistry and ecology of many freshwaters globally. Its biogeochemical impact on wetland functioning is strongly mediated by the microbiome associated with its roots. However, little is known about the structure and function of this WH rhizobiome and its relation to w...

Reservoir sediments exposed to air due to water level fluctuations are strong sources of atmospheric carbon dioxide (CO2). The spatial variability of CO2 fluxes from these drawdown areas are still poorly understood. In a reservoir in southeastern Brazil, we investigated whether CO2 emissions from drawdown areas vary as a function of neighboring lan...

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 ≤...

Data on salinity tolerance of aquatic plant species are scarce, but required to better understand species' responses in multiple stressed environments. We analyzed data from a Dutch Water board in the province of Zeeland according to the occurrence of plant taxa in relation to salinity (chloride concentration). The dataset contained 862 samples of...

Artificial water bodies like ditches, fish ponds, weirs, reservoirs, fish ladders, and irrigation channels are usually constructed and managed to optimize their intended purposes. However, human-made aquatic systems also have unintended consequences on ecosystem services and biogeochemical cycles. Knowledge about their functioning and possible addi...

• Pigments in lake surface sediments integrate both benthic and pelagic primary producer composition at the whole‐lake ecosystem level. • We gathered a comprehensive set of water chemistry, morphometric, physical and biological lake variables, catchment and climate characteristics, and geographical descriptors. We used multiple regressions to relat...

The role of tropical lakes and reservoirs in the global carbon cycle has received increasing attention in the past decade, but our understanding of its variability is still limited. The metabolism of tropical systems may differ profoundly from temperate systems due to the higher temperatures and wider variations in precipitation. Here, we investiga...

Small water systems are important hotspots of greenhouse gas (GHG) emission, but estimates are poorly constrained as data are scarce. Small ponds are often constructed in urban areas, where they receive large amounts of nutrients and therefore tend to be highly productive. Here, we investigated GHG emissions, seasonal and diel variation, and net ec...

Global warming may intensify eutrophication of shallow lakes by affecting nutrient loading, evaporation rates, and water level and thus produce major changes in food webs. We investigated to what degree food webs in tropical humid lakes differed from those in more eutrophic semi-arid lakes of the same latitude. Our results indicate that the catchme...

River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to...