Hans-Peter Grossart

• Prof. Dr.
• Speaker of Research Focus Aquatic Biodiversity at Leibniz Institute of Freshwater Ecology and Inland Fisheries

The cryosphere faces increasing threats from anthropogenic pollutants, including per- and polyfluoroalkyl substances (PFAS), a class of synthetic chemicals produced in significant quantities and released into the environment for over seven decades. PFAS are widely utilized for their water- and grease-resistant properties in numerous industrial, hou...

Ecological impacts of tire wear particles (TWPs) on microbial communities and biogeochemical cycles in freshwater remain largely unknown. Here, we conducted a microcosm experiment to investigate interactions between the overlying water and sediment without and with TWPs addition in a rural vs. urban lake system. Our results revealed the degree of c...

Comparing cases of parasitism and predation that lead to victim death, parasites need more time to complete victim exploitation. This longer ‘interaction durability' delays energy transfer from host to parasite. During exploitation, parasite virulence differentiates the infected from the susceptible host dynamics. However, how this parasite charact...

Evaluating progress toward achieving freshwater conservation and sustainability goals requires transforming diverse types of data into useful information for scientists, managers, and other interest groups. Despite substantial increases in the volume of freshwater data collected worldwide, many regions and ecosystems still lack sufficient data coll...

Abstract Plasmids are key determinants in microbial ecology and evolution, facilitating the dissemination of adaptive traits and antibiotic resistance genes (ARGs). Although the molecular mechanisms governing plasmid replication, maintenance, and transfer have been extensively studied, the specific impacts of urbanization-induced pollution on plasm...

Trophic interactions determine food web structure and influence biodiversity, community structure, ecosystem functioning, and food web responses to global change. These interactions are highly flexible, changing on temporal scales from diurnal to evolutionary times due to phenotypic plasticity, rapid evolution and species sorting. Small-scale exper...

In a survey of tropical plant diseases in southern and southeastern Iran, samples of diseased Mangifera indica and Psidium guava leaves with necrotic symptoms were collected between 2021 and 2022. Six representative isolates of Neopestalotiopsis and Robillarda (three isolates for each) were studied using morphological characteristics as well as mul...

Eutrophication in the Baltic Sea has caused an imbalance in the inorganic nitrogen (N) to phosphorus (P) ratio, leaving excess phosphate (PO4) after the phytoplankton spring bloom that terminates after N depletion. Using monitoring data, we demonstrated that the PO4 concentration has continued to increase in the outermost Gulf of Finland during pas...

Amplicon sequencing tools such as metabarcoding are commonly used for thorough characterisation of microbial diversity in natural samples. They mostly rely on the amplification of conserved universal markers, mainly ribosomal genes, allowing the taxonomic assignment of barcodes. However, linking taxonomic classification with functional traits is no...

The use of water as a weapon in highly industrialized areas in the Russo-Ukrainian war has resulted in catastrophic economic and environmental damages. We analyze environmental effects caused by the military destruction of the Kakhovka Dam. We link field, remote sensing, and modeling data to demarcate the disaster’s spatial-temporal scales and outl...

Understanding the mechanisms driving community structure and dynamics is crucial in the face of escalating climate change, including increasing incidences of extreme weather. Cell size is a master trait of small organisms that is subject to a trade‐off between resistance to grazing and competition for resources, and thus holds potential to explain...

Here, we assessed the heteroaggregation of polystyrene (PS) and poly(vinyl chloride) (PVC) nanoplastics with SiO2 as a model of natural colloids. Homoaggregation and heteroaggregation were evaluated as a function of CaCl2 (0–100 mM) and natural organic matter (NOM) (50 mg L–1) at a designated concentration of nanoplastics (200 μg L–1). Critical coa...

Long‐term climatic differences shape the ecological memory of soil bacterial communities, which refers to the ability of past events to influence current environmental responses. However, their ecological mechanisms and consequences for bacterial responses to current environmental changes remain largely unknown, particularly in terms of temporal dy...

Artificial light propagating towards the night sky can be scattered back to Earth and reach ecosystems tens of kilometres away from the original light source. This phenomenon is known as artificial skyglow. Its consequences on freshwaters are largely unknown. In a large-scale lake enclosure experiment, we found that skyglow at levels of 0.06 and 6...

Intensifying extreme droughts are altering lentic ecosystems and disrupting services provisioning. Unfortunately, drought research often lacks a holistic and intersectoral consideration of drought impacts, which can limit relevance of the insights for adaptive management. This literature review evaluated the current state of lake and reservoir extr...

The rising atmospheric concentration of CO2 is a major concern to society due to its global warming potential. In soils, CO2-fixing microorganisms are preventing some of the CO2 from entering the atmosphere. Yet, the controls of dark CO2 fixation are rarely studied in situ. Here, we examined the gene and transcript abundance of key genes involved i...

During a survey on the biodiversity of oomycetes in aquatic environments in northwest Iran (East Azarbaijan and West Azarbaijan provinces), three Pythium and four Globisporangium isolates were recovered from agricultural water pools and irrigation canals, respectively. Through a polyphasic approach combining morphology and phylogenetic analysis usi...

Free use and redistribution of data (i.e., Open Data) increases the reproducibility, transparency, and pace of aquatic sciences research. However, barriers to both data users and data providers may limit the adoption of Open Data practices. Here, we describe common Open Data challenges faced by data users and data providers within the aquatic scien...

Life in hyperarid regions has adapted to extreme water scarcity through mechanisms like salt deliquescence. While halite (NaCl) crusts have been intensively studied and identified as one of the last habitats under hyperarid conditions, other less common hygroscopic salt crusts remain unexplored. Here, we investigated newly discovered deliquescent s...

With the simultaneous growth in interest from the mycological community to discover fungal species and classify them, there is also an important need to assemble all taxonomic information onto common platforms. Fungal classification is facing a rapidly evolving landscape and organizing genera into an appropriate taxonomic hierarchy is central to be...

River ecosystems face escalating challenges due to altered flow regimes from human activities, such as urbanization with hydrological modifications. Understanding the role of microbial communities for ecosystems with changing flow regimes is still incomplete and remains at the frontier of aquatic microbial ecology. In particular, influences of rive...

This study aimed to investigate the presence and diversity of fungal parasites in Arctic coastal microphytobenthic communities. These communities represent a key component in the functioning of Arctic trophic food webs. Fungal parasites, particularly Chytridiomycota (chytrids), play significant roles by controlling microalgal bloom events, impactin...

Lakes are important sentinels of climate change and may contribute over 30% of natural methane (CH4) emissions; however, no earth system model (ESM) has represented lake CH4 dynamics. To fill this gap, we refined a process‐based lake biogeochemical model to simulate global lake CH4 emissions, including representation of lake bathymetry, oxic methan...

Tetrapyrroles such as heme, chlorophyll, and vitamin B12 are essential for various metabolic pathways. They derive from 5-aminolevulinic acid (5-ALA), which can be synthesized by a single enzyme (5-ALA synthase or AlaS, Shemin pathway) or by a two-enzyme pathway. The genomes of some bacteriophages from aquatic environments carry various tetrapyrrol...

Estuaries are important components of the global carbon cycle; exchanging carbon between aquatic, atmospheric, and terrestrial environments, representing important loci for blue carbon storage and greenhouse gas emissions. Estuarine particles are especially important due to their microbial transformation and vertical/horizontal transport. We used m...

In recent decades, inland water remote sensing has seen growing interest and very strong development. This includes improved spatial resolution, increased revisiting times, advanced multispectral sensors and recently even hyperspectral sensors. However, inland waters are more challenging than oceanic waters due to their higher complexity of optical...

Benthic bacteria in stream ecosystems drive organic matter mineralization. However, knowledge on how this ecosystem function is driven by bacterial community composition in interaction with environmental conditions and organic matter resources is poor. This is especially true when considering the regional scale of river networks, at which environme...

Microplastics (MPs) have introduced new surfaces for biofilm development and gene exchange among bacteria. We investigated Tire Wear Particles (TWPs) for their involvement in horizontal gene transfer (HGT), particularly in relation to associated metals in the matrices of TWPs. We employed red-fluorescently tagged E. coli strain as a donor with gree...

Introduction In riverine ecosystems, dynamic interplay between hydrological conditions, such as flow rate, water level, and rainfall, significantly shape the structure and function of bacterial and microeukaryotic communities, with consequences for biogeochemical cycles and ecological stability. Lake Taihu, one of China’s largest freshwater lakes,...

Biochar is frequently employed to ameliorate saline-affected paddy soil. However, there are controversial research findings regarding the applicability of biochar for the enhancement of soil physicochemical properties and agricultural (crop) yield, particularly under conditions of wastewater irrigation in agricultural production. This study investi...

Telonemia are one of the oldest identified marine protists that for most part of their history have been recognized as a distinct incertae sedis lineage. Today, their evolutionary proximity to the SAR supergroup (Stramenopiles, Alveolates, and Rhizaria) is firmly established. However, their ecological distribution and importance as a natural predat...

This study was conducted with the aim of isolation and identification of oomycetes from agricultural water sources and aquatic environments in East Azarbaijan, West Azarbaijan, Ardabil, and Guilan provinces, Iran. Sampling was carried out in 2021 from various locations in the aforementioned provinces, including lakes, rivers, ponds, springs, aquati...

Antibiotic resistance is an escalating global health concern, exacerbated by the pervasive presence of antibiotic resistance genes (ARGs) in natural environments. The Yangtze River, the world's third-longest river, traversing areas with intense human activities, presents a unique ecosystem for studying the impact of these genes on human health. Her...

Freshwater ecosystems are characterized by their unique longitudinal and lateral habitat connectivity. As a result, spatial units in freshwater-specific analyses can often not be considered independent of each other. Accounting for this connectivity in modelling analyses requires advanced skills in Geographic Information Systems (GIS) for adequatel...

Photosynthetic carbon sequestration and microbial carbon metabolism are major processes of algae-bacteria interactions, affecting pollutant degradation as well as fundamental biogeochemical cycles in aquatic systems. Human-induced land-use changes greatly alter the molecular composition and input of terrestrial dissolved organic matter (DOM) in inl...

This invited commentary paper discusses the concept of elevated antibiotic resistance genes as a global change factor.

The phosphorus (P) concentration is increasing in parts of the Baltic Sea following the spring bloom. The fate of this excess P-pool is an open question and here we investigate the role of microbial degradation processes in the excess P assimilation phase. During a 17-day-long mesocosm experiment in the south-west Finnish archipelago, we examined n...

Life in hyperarid regions has adapted to extreme water scarcity by using salt deliquescence. Here, we investigated newly discovered deliquescent soil surfaces in the Atacama Desert, containing substantial amounts of nitrates, to evaluate their habitability for microorganisms. We characterized the environment regarding water availability and biogeoc...

In terms of lifestyle, bacterioplankton can be classified as free-living (FL) and particle-attached (PA) forms, and both play essential roles in biogeochemical cycling in aquatic ecosystems. Structure, distribution, and community assembly of FL and PA bacteria in plateau riverine waterbodies are largely unknown. Therefore, we explored the seasonal...

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...

Zooplankton communities are the primary conduit of energy from phytoplankton to planktivorous fish in freshwater ecosystems and play key roles in the functioning of these systems. Therefore, they are often proposed as ecological indicators. However, most zooplankton research focuses on a single waterbody or region, and insights from such studies ma...

Iron (Fe) plays an important role in the biogeochemical cycling of carbon and nutrients in aquatic systems. Reactive Fe phases can interact with organic carbon and facilitate the removal of carbon from the biogeochemical cycle; however, this important ecosystem function is often strongly controlled by Fe availability. Due to pollution from lignite...

Estuarine zonation and community assemblages are frequently correlated with salinity, although the extent or nature of this correlation varies considerably among the published studies. While a smooth transition in biological communities is often conceptualized in association with estuarine fresh, brackish, and marine conditions, many studies have s...

Nanoplastics are anticipated to be ubiquitous in various environmental compartments. However, challenges in analytical methods hinder our understanding of risks related to specific nanplastics characteristics such as size and chemical compositions, and interactions between nanoplastics and microorganisms. In this study, we applied fit-for-purpose a...

Succession is a fundamental aspect of ecological theory, but studies on temporal succession trajectories and ecological driving mechanisms of plastisphere microbial communities across diverse colonization environments remain scarce and poorly understood. To fill this knowledge gap, we assessed the primary colonizers, succession trajectories, assemb...

The world's 1.4 million lakes (≥10 ha) provide many ecosystem services that are essential for human well‐being; however, only if their health status is good. Here, we reviewed common lake health issues and classified them using a simple human health‐based approach to outline that lakes are living systems that are in need of oxygen, clean water and...

Background Aerobic anoxygenic phototrophic (AAP) bacteria are heterotrophic bacteria that supply their metabolism with light energy harvested by bacteriochlorophyll-a-containing reaction centers. Despite their substantial contribution to bacterial biomass, microbial food webs, and carbon cycle, their phenology in freshwater lakes remains unknown. H...

"There are no scientifically justified obstacles to protecting biodiversity in all its beauty and diversity. There are only six years left to achieve the biodiversity targets by 2030. We must work together now to get there in time." In the 10 Must Knows from Biodiversity Science 2024, 64 scientists have further developed their well-founded and div...

Fungi in marine ecosystems play crucial roles as saprotrophs, parasites, and pathogens. The definition of marine fungi has evolved over the past century. Currently, “marine fungi” are defined as any fungi recovered repeatedly from marine habitats that are able to grow and/or sporulate in marine environments, form symbiotic relationships with other...

Spatio-temporal variability of sediment-mediated methane (CH4) production in freshwater lakes causes large uncertainties in predicting global lake CH4 emissions under different climate change and eutrophication scenarios. We conducted extensive sediment incubation experiments to investigate CH4 fluxes in Lake Stechlin, a deep, stratified temperate...

Cyanobacterial blooms present substantial challenges to managers and threaten ecological and public health. Although the majority of cyanobacterial bloom research and management focuses on factors that control bloom initiation, duration, toxicity, and geographical extent, relatively little research focuses on the role of loss processes in blooms an...

The isotopic ratio ¹⁸ O/ ¹⁶ O of dissolved O 2 in aquatic systems is affected by the preferential biological uptake of ¹⁶ O ( ε ). Studies over the past six decades reveal that during incubation experiments, the isotopic effect of microorganism respiration ( ε organism ) varies in the range of −18‰ to −22‰. In contrast, natural variations in the de...

Changes in salinity have a profound influence on ecological services and functions of inland freshwater ecosystems, as well as on the shaping of microbial communities. Bacterioplankton, generally classified into free-living (FL) and particle-attached (PA) forms, are main components of freshwater ecosystems and play key functional roles for biogeoch...

Dolichospermum is a cyanobacterial genus commonly associated with toxic blooms in lakes and brackish water bodies worldwide, and is a long-term resident of Lake Stechlin, northeastern Germany. In recent decades, shifts in the phosphorus loading and phytoplankton species composition have seen increased biomass of Dolicho-spermum during summer blooms...

Eutrophication in the Baltic Sea has caused an imbalance in the inorganic nitrogen (N) to phosphorus (P) ratio, leaving excess phosphate (PO4) remaining after the phytoplankton spring bloom that terminates after N depletion. Here we investigated the fate of such excess phosphate in a two-week mesocosm (1.2 m3) experiment. Treatments included a non-...

In the northern Baltic, post-spring-bloom low dissolved inorganic nitrogen to phosphorus conditions, degradation of N-rich organic matter potentially supports the drawdown of excess phosphate. During a 17-day-long mesocosm experiment in the south-west Finnish archipelago, we examined nitrogen, phosphorus and carbon acquiring extracellular enzyme ac...

The aim of this study was to isolate and identify oomycetes from agricultural water sources and aquatic environments in East Azerbaijan province. Sampling was conducted during the spring, summer, and fall of the year 2021 from various agricultural water sources and aquatic environments, including lakes, rivers, ponds, springs, algae within water, a...

Rising atmospheric concentration of CO2 is a major concern to society due to its global warming potential. In soils, CO2 fixing microorganisms are preventing a part of the CO2 from entering the atmosphere. Yet, the pathways behind dark CO2 fixation are rarely studied in situ. Here we examined the environmental controls on the abundance and expressi...

Permafrost, a vast storage reservoir of frozen organic matter, is rapidly thawing due to climate change, releasing previously preserved carbon into the environment. This phenomenon has significant consequences for microbial communities, including fungi, inhabiting permafrost-associated regions. In this review, we delve into the intricate interplay...

Although scientific research has identified the causes of undesirable ecological changes in fresh waters, translating the results of research into practical conservation and management, and raising awareness of the need for action, is often inadequate. This Viewpoint considers the present coverage of conservation‐related freshwater research, the ap...

The Global Consortium for the Classification of Fungi and fungus-like taxa is an international initiative of more than 550 mycologists to develop an electronic structure for the classification of these organisms. The members of the Consortium originate from 55 countries/regions worldwide, from a wide range of disciplines, and include senior, mid-ca...

Tetrapyrroles such as heme, chlorophyll, or vitamin B12 are among the most complex molecules synthesised by nature and play a crucial role in many vital processes such as respiration, photosynthesis, methanogenesis, and catalysis. All modified tetrapyrroles are derived from the common precursor molecule 5-aminolevulinic acid (5-ALA). However, 5-ALA...

Declining oxygen concentrations in the deep waters of lakes worldwide pose a pressing environmental and societal challenge. Existing theory suggests that low deep-water dissolved oxygen (DO) concentrations could trigger a positive feedback through which anoxia (i.e., very low DO) during a given summer begets increasingly severe occurrences of anoxi...

Lakes worldwide are affected by multiple stressors, including climate change. This includes massive loading of both nutrients and humic substances to lakes during extreme weather events, which also may disrupt thermal stratification. Since multi-stressor effects vary widely in space and time, their combined ecological impacts remain difficult to pr...