The researchers of the Functional Algology Research Group, operating at the Tisza Research Department of the Institute of Aquatic Ecology of the ELKH Centre for Ecological Research (CER), in collaboration with experts from the Department of Environment, Nature Protection and Waste Management of the Győr-Moson-Sopron County Government Office, investigated whether one-off drought events and trend-like precipitation decrease result in similar changes in the composition of diatom assemblages of the Rába River, one of the largest rivers in Hungary. The results clearly highlighted that the continuous decrease in annual precipitation has a much more significant impact on the composition and biodiversity than a single dry year. The paper presenting the research was published in the prestigious scientific journal Ecological Indicators.

Weather extremes and the impact of drought are immediately noticeable, for example, in agricultural areas or forests, and although perhaps less perceptible, they also have significant consequences for the ecosystems of rivers.

The researchers of the Functional Algology Research Group, operating at the Tisza Research Department of the Institute of Aquatic Ecology of the ELKH Centre for Ecological Research (CER), in collaboration with experts from the Department of Environment, Nature Protection and Waste Management of the Győr-Moson-Sopron County Government Office, investigated the long-term changes in the composition of the benthic diatom assemblage of the Rába River.

The Rába is the third largest river in Hungary and the most important domestic tributary of the Danube. Over the past five years, environmental protection experts have observed a significant decrease in precipitation within its catchment area. They applied to CER researchers with the observation that the trend-like, continuous decrease in precipitation likely affects the composition of the benthic diatom assemblages.

During the joint work, they sought to find the answer to whether one-off drought events and trend-like precipitation decrease result in similar changes in the composition of the river’s benthic diatom assemblages. It has been shown in other ecosystems that the resilience of the assemblages can vary depending on whether drought occurs regularly, for extended periods, or only intermittently.

Maintaining the good condition of our rivers and reducing harmful effects, such as nutrient load, are important societal interests. The legal framework for this is determined by the EU Water Framework Directive, which Hungary also follows. In order to characterize and monitor the ecological status of our surface watercourses, experts regularly monitor the river ecosystems, in which benthic diatoms play a key role. These tiny organisms have a significant function in the food web and primary production.

Although microscopic in size, the biofilm they create is visible to the naked eye and can be felt, for example, on the steps of beaches, on rocks, and on shoreline and aquatic plants. Perhaps few people are aware of the wonders hidden within this film. When magnified, it reveals a micro-world resembling a small forest, where, similar to the ground level of a forest, there are species adhering on the surface, often very small, as well as prominent, branching species that resemble trees. Just as forests, the biofilm is also shaped by the environment. The number of species and individuals present, as well as the species with specific characteristics that can occur in a given biofilm, greatly depend on the influences affecting the water. Besides nutrient load, other threatening factors such as the increase in pharmaceutical residues, rising water temperature, changes in water residence time, drastic decrease in water level and flow, or the receding of flash floods significantly influence the composition of this tiny forest. Ultimately, this will also have an impact on higher taxonomic groups, such as aquatic invertebrates and fish,” said Viktória B-Béres, one of the lead authors of the study.

In order to understand these processes, the analysis and evaluation of long-term datasets are of paramount importance. For the investigation, the authors of the study utilized datasets available for the Rába River, covering a period of fifteen years. The period from 2007 to 2021 was divided into two groups based on annual precipitation. Between 2007 and 2016, fluctuating years of both drier and wetter conditions alternated, while from 2017 onwards, consistently decreasing annual precipitation was characteristic.

“Our results showed that one-off dry events had little influence on the composition and biological diversity of benthic diatom assemblages. In contrast, continuously decreasing precipitation ‒ dry periods ‒ significantly reduced species-level and functional diversities, the latter based on individual characteristics. Using the previous analogy, it was as if our tiny forest transformed into a barren landscape. Small-sized species that strongly adhere to the substrate, such as Amphora pediculus and Reimeria sinuata, became dominant, while the proportion of larger tree-like species decreased significantly. This is problematic because this type of algae plays an important role in the river’s food web as a food source for snails and macroinvertebrates. Therefore, their absence or decline in population size can have detrimental effects on the larger organisms inhabiting the river,” added Viktória B-Béres.

In a recently published study, researchers analyzed for the first time the differences in the effects between one-off dry weather events and trend-like changes in precipitation on the benthic diatom assemblages of a large river. The results clearly highlighted that the continuous decrease in annual precipitation has a much more significant impact on the composition and biodiversity than a single dry year. Climate scenarios project extreme water balance conditions in the near future, including longer periods of low precipitation. Therefore, any knowledge that can predict changes in the microscopic river ecosystems can assist in the development of action plans by authorities to preserve the functional and structural characteristics of riverine ecosystems, and thus maintain the ecosystem services provided by benthic algal assemblages. The study indirectly draws attention to the vulnerability of even large, perennial riverine ecosystems during dry periods, emphasizing the importance of responsible water management. The researchers are asking the public to report any incidents of extraordinary water pollution, untreated wastewater discharge, shoreline littering, or large amounts of mussel or fish carcasses to the environmental protection departments of e.g. the Győr-Moson-Sopron County or Hajdú-Bihar County Government Offices.

Photo: Sampling from the Rába River

Publication:

Zsuzsanna Nemes-Kókai, Krisztián Kovács, Gábor Borics, Rezső Mayer, Zoltán Novák, Ákos Gábor Robotka, Júlia József, Károly Érczes, Áron Lukács, Viktória B-Béres (2023). Continuous precipitation loss induced more pronounced compositional and diversity changes in the lotic phytobenthos than one-off drought events. Ecological Indicators, Volume 148, 2023. 110051, ISSN 1470-160X. DOI: 10.1016/j.ecolind.2023.110051.

Researchers from the Institute of Aquatic Ecology of the ELKH Centre for Ecological Research (CER) led by Csaba Vad, conducted a study in an international collaboration to explore the resilience of aquatic ecosystems to the negative impacts of heatwaves. They also investigated whether dispersal from surrounding habitats, i.e., the arrival of other species, could accelerate ecosystem recovery. During their experiment on plankton communities in mesocosms, the researchers found that the heatwave drastically reduced the biomass of plankton due to the negative impact on primary consumer zooplankton, such as water fleas. Dispersal from surrounding habitats had limited effect in this study, somewhat positively influencing only the growth of phytoplankton. As a result of the heatwave, both the composition and trophic structure of the communities changed, which could have long-term implications for ecosystem functioning. The study presenting the results was published in one of the leading international ecological journals, Global Change Biology.

The increasingly frequent and intense heatwaves associated with global climate change pose a significant threat to biodiversity, ecosystem functioning, and the ecosystem services provided to humans. Consequently, it becomes crucial to understand the mechanisms that affect the resilience of communities in the face of extreme temperature events, including their resistance to temperature stress and their subsequent recovery. This knowledge is essential for improved prediction and mitigation of biodiversity loss and its far-reaching implications. Moreover, it enables the application of effective strategies to adapt to climate change.

In a research led by Csaba Vad, researcher at the Institute of Aquatic Ecology of CER, an international research group investigated whether connectivity through dispersal facilitates ecosystem adaptation to heatwave-induced stress (“spatial insurance hypothesis”). The study, conducted over a period of one and a half months, took place in artificial lakes known as mesocosms. In these experimental systems, the processes occurring in natural ecosystems can be modeled much more realistically compared to laboratory conditions. Moreover, they allow for the isolated examination of individual stressors and underlying mechanisms, which would not be feasible in natural habitats due to their complexity.

According to the results, the heatwave led to a decrease in plankton biomass, primarily due to its negative impact on zooplankton, such as water fleas. In the case of a natural lake, for example, this could lead to temporary reduction in food sources available for fish or even the development of algae blooms, as these small microscopic organisms play an important role in regulating algae levels. The effect of dispersal from surrounding habitats in this experiment was relatively minor, and it was only evident in the faster post-heatwave growth of phytoplankton. The results showed that the community biomass returned to the undisturbed level regardless of dispersal. However, the composition and trophic structure of the community changed, which could potentially result in long-term alterations in ecosystem functioning.

Based on the experiment, it can be concluded that even a short heatwave of about one week can alter the species composition and interactions within aquatic ecosystems, potentially leading to long-term consequences. These effects can be further aggravated by the fragmentation of ecosystems resulting from habitat loss, increasing spatial isolation of remaining habitats and reducing the dispersal of organisms. Ecologists urge for further long-term research to understand the impacts of heatwaves and develop possible adaptation strategies.

The research was carried out within the framework of the H2020 AQUACOSM project, with the support of H2020 AQUACOSM-plus and the National Multidisciplinary Laboratory for Climate Change.

Photos: Zsófia Horváth

Publication: 

Vad Cs. F., Hanny-Endrédi A., Kratina P., Abonyi A., Mironova E., Murray D. S., Samchyshyna L., Tsakalakis I., Smeti E., Spatharis S., Tan H., Preiler C., Petrusek A., Bengtsson M. M. & Ptacnik R. (2023). Spatial insurance against a heatwave differs between trophic levels in experimental aquatic communities. Global Change Biology 29: 3054–3071. (IF₂₀₂₁: 13.211 | SCimago₂₀₂₂: D1)

The researchers of the ELKH Centre for Ecological Research (CER) investigated the spread of the non-native great blanketflower in Hungary within the framework of the National Laboratory for Health Security project. The aim of the research was to evaluate the impact of the species on the local plant community and determine its invasive potential through its functional traits. Based on the results, the great blanketflower does not currently appear to be a strong ecosystem-transforming species, but there is a risk that due to climate change, the local environment in Hungary will become more suitable for it in the future, leading to strong speading and becoming invasive. Therefore, the researchers do not recommend planting blanketflower species in gardens. They also suggest surveying non-native ornamental plant populations, conducting long-term monitoring and a more detailed assessment of the traits that influence their spread. The publication presenting the results was published in the scientific journal NeoBiota.

Ornamental plants are one of the main sources of species becoming invasive. During their planting, they are introduced to new habitats where humans create favourable living conditions through irrigation and maintenance. Later, in natural habitats, they can easily occupy open niches created by human disturbances and the warming effects of climate change. The blanketflower has followed this path as well, and its ecological impacts were studied by researchers of CER along with several other new, potentially dangerous species within the recently initiated National Laboratory for Health Security project.

The great blanketflower and its relative, the Indian blanket, along with their hybrid, are globally planted ornamental plant species. Reports have already been made in several countries about the great blanketflower escaping from gardens and naturalizing in various new habitats, but its invasive behavior has been relatively unknown until now. However, it seems that in the past few decades, this species has found suitable habitats in Hungary and from a naturalized species it has become invasive in several locations. “Our aim was to map the distribution of the great blanketflower in Hungary, evaluate its impact on the local plant community, and determine the species’ invasive potential through its functional traits,” summarized Gabriella Süle, Phd, a assistant research fellow at CER.

Based on the distribution data collected here, the great blanketflower occurs in Hungary mainly as casual escapes yet. This species, which blooms profusely throughout the year and is extremely colorful, requires little to no care. Therefore, owners allow it to spread, and we can often see it occupying more and more space in front of gardens. However, it became naturalized in recent years, and invasive populations have also been found in significant numbers within the country. The species is mainly observed near gardens and disturbed habitats, but it has also appeared in natural and semi-natural grasslands. It successfully spreads in disturbed, species-poor, sandy, open habitats. Its spread affects the composition of the local plant community, reducing, for example, the species richness of local plants. Based on its functional traits, its well germination capacity, extremely long flowering period, the large absorbing and adhering surface provided by its roots, and its spread by grazing animals’ fur, mainly sheep, can promote its invasive spread. Currently, the great blanketflower does not appear to be a strong ecosystem-transforming species, but more attention needs to be paid to it because there is a risk that the local environment in Hungary will become increasingly suitable for it due to drier weather caused by climate change, leading to strong spread and becoming invasive, primarily in sandy soils.

“Due to all of these, we do not recommend planting blanketflower species in gardens, as they can easily escape and establish in natural plant communities. Furthermore, we suggest considering banning their distribution in seed mixes. To control invasive populations in natural habitats, there is a need to develop an effective eradication method” emphasized Gabriella Süle, Phd.
Assessing the great blanketflower and similar non-native ornamental plant populations, conducting long-term monitoring, and performing a more detailed evaluation of the traits influencing their spread would be important in order to prevent the escape of species planted in gardens into the natural habitats on time.

Assessing and managing the ecological, economic, and societal threats posed by invasive species similar to the great blanketflower is one of the focuses of the Division of Invasion Biology within the National Laboratory for Health Security project. The research is being carried out within the framework of the Széchenyi Plan Plus program with the support of the RRF-2.3.1-21-2022-00006 project.

Publication:
Süle G, Miholcsa Z, Molnár C, Kovács-Hostyánszki A, Fenesi A, Bauer N, Szigeti V (2023) Escape from the garden: spreading, effects and traits of a new risky invasive ornamental plant (Gaillardia aristata Pursh). NeoBiota 83: 43-69. https://doi.org/10.3897/neobiota.83.97325

Alkaline soda pans of Hungary are special representatives of inland saline waters in the interior of the continents. The largest number of soda pans in Eurasia is found in the Carpathian Basin, and these lakes are also important resting and feeding areas for migratory birds in the European-African bird migration routes. Evidence is mounting that globally, aquatic habitats and waterbird populations are being rapidly declined by the land-use and land cover changes of recent decades (drainage, run-off), and climate change: rising temperatures and changing rainfall patterns. Waterbird populations play an important role in trophic- and host-parasite networks, and their cultural and recreational role is also important, but as bird populations and habitats decline, these ecological services are also declining.

Emil Boros, Senior Research Fellow at the Centre for Ecological Research, Institute of Aquatic Ecology, has been studying the interaction between waterbird populations and soda pans for many years. In an earlier publication in the Science of the Total Environment they found that waterbirds contribute high phosphorus loading (P) to the shallow saline lakes through their droppings, i.e. birds act as vectors of external phosphorus sources, a process called guanotrophication (bird-induced nutrient enrichment). Waterbirds, such as large-bodied herbivores (goose and duck species) and medium-bodied omnivores (e.g. gulls) have been shown to be 64% responsible for the extremely high phosphorus content of natural soda pans. However, it was also found that, the hypertrophic state of water was in contradiction with the limited primary production of natural soda pans due to the characteristics of the lakes: shallow water depth, high alkalinity (PH ≥ 9), and intermittent hydrological cycle.

In a further investigation about the interaction between inland saline aquatic ecosystems and waterbirds the aim was to show whether the ecological/trophic attributes of saline water bodies could be predicted on multi spatial-scales by different groups (guilds) of waterbirds. Also published in the prestigious journal Science of the Total Environment, Emil Boros and colleagues studied a vast area of 1700 km by 1000 km at different spatial scales in the steppe and semi-desert region of Kazakhstan, where 63 sample area were selected. Nearly 100 waterbird species occurred in the sample areas and were classified into three groups according to their role in nutrient cycling and nutrient turnover: net-importers (large herbivores e.g. geese, cranes), importer-exporters (omnivorous ducks and gulls) and net-exporters (various herbi-, omni- and piscivorous species), based on Boros’s classification method. The abundance, biomass and diversity of these bird groups (guilds) were compared with the attributes of the inland waters on multi spatial scales e.g. water depth, chlorophyll content, and at larger spatial scales, with the land cover data found in the 1 and 10 km radius around the ponds e.g. grassland or agricultural land.

Their results showed that the occurrence of the above waterbird groups was strongly correlated with the attributes of the saline aquatic ecosystems on multi-spatial scale. Water cover and salinity are the main attributes predicting of the type of bird group that occurs in a given environment. The importer-exporter and net exporter bird groups showed positive correlations with productivity metrics and water depth of the waters, while the importers were predicted by the surrounding pond environment e.g. grassland.
The practical significance of this study is that it quantifies this ecosystem services provided by waterbirds, their role in nutrient cycling, which is essential for systematic monitoring and habitat management. The classification system and methodology described in this study can be used to estimate certain environmental attributes of inland water bodies for large geographic regions by counting waterbird populations. In the future, this will provide an opportunity to use birds to estimate ecosystem function and services of aquatic systems, which in turn will require further methodological studies.

Publications:

Emil Boros, Zarina Inelova, Zsuzsanna Lánczos, Zsolt Végvári: Waterbird guilds predict environmental attributes of inland saline aquatic ecosystems on multi-spatial scales,
Science of the Total Environment, Volume 855, 2023.
https://doi.org/10.1016/j.scitotenv.2022.158845.
https://www.sciencedirect.com/science/article/pii/S0048969722059447

Emil Boros, Anita Takács, Péter Dobosy, Lajos Vörös: Extreme guanotrophication by phosphorus in contradiction with the productivity of alkaline soda pan ecosystems,
Science of the Total Environment, Volume 793, 2021.
https://doi.org/10.1016/j.scitotenv.2021.148300.
https://www.sciencedirect.com/science/article/pii/S0048969721033714

Photos: Emil Boros – Red-necked Phalarope and Lake Balkas

The understanding and importance of traditional ecological knowledge systems is increasingly recognised worldwide as a means to develop more effective policies in today’s crises, e.g. in nature conservation or grassland management. Zsolt Molnár, scientific advisor at the Centre for Ecological Research, has been researching the traditional ecological knowledge of pastoralists for more than 20 years. His Iranian student is the first author of a joint publication with European, Asian and African authors in the Journal of Environmental Management.

Unusual for academic publications, the publication is a collaboration between researchers and practising pastoralists. “Since the holders of traditional knowledge are mostly not researchers but herders, farmers, fishermen, when a researcher works with their knowledge, the ethical approach is for these ‘non-scientific’ professionals to also become co-authors. After all, the new publication is the result of collective thinking, knowledge co-production. Such recognition of traditional knowledge is now, fortunately, becoming more and more common” – said Zsolt Molnár.

Herders often graze in landscapes that are less suitable for crop production due to climatic extremes or soil conditions. Traditional grazing systems exist in very different natural environments, such as tundra, steppe, savannah, desert, mountainous areas. Pastoralist communities have locally relevant, multi-generational traditional ecological knowledge of pasture plants on which they base the utilisation of their pastures.

During the research, the authors collected the knowledge of herders on pasture (and hay meadow) plants and plant-livestock interactions in a review article. They analysed 24 of the 372 relevant scientific articles and 18 of the 105 videos about herders and their pastures. In addition, semi-structured interviews were conducted with practising herders in Iran, Mongolia, Kenya, Poland and Hungary to discuss the findings and conclusions.

Thirty-five indicators were identified in the scientific papers and documentaries of how herders ‘see’ forage plants. These indicators described both the botanical features of the plants and the livestock behaviour during grazing, as well as the impact of forage plants on the condition and health of livestock. The indicators were used by herders in management decisions to optimise grazing, the availability and quality of fodder grasses, and the appropriate way of grazing. Although herders around the world are very different, their knowledge of pasture grasses and the relationship between livestock and forage plants is remarkably similar. The researchers identified ten general principles that were common globally, almost regardless of location or habitat type. Such a global synthesis has never been done before.

Perhaps the most important key global principle is the livestock-centred approach explained Zsolt Molnár: “herders see plants through the “mouth of the livestock”. While in the pasture together, herders and livestock reciprocally learn from each other. The condition of the pasture grasses is closely monitored by the herders, who graze each patch in a targeted way, while often planning livestock movements with surprisingly strategic attention to detail, on a daily, weekly and monthly basis. The aim is to make the best use of the available grass as a resource and to ensure also the long-term ‘well-being’ of the pastures (see more details in this film). The lexical details of this knowledge are of course highly specific to the place, but the principles are globally general. You might ask that it’s good, but why is it important? It may come as a surprise, but even in cases where the state or a national park develops supporting measures and regulatory systems for pastoral grazing, it is easy to develop rules that have harmful effects. Because decision-makers often do not sufficiently understand the pastoral world, which is so different from our own. Our article points out that there are general principles that we can build on, and that we can take into account to create better policies, both ecologically and culturally.”

Researchers hope that a better understanding of pastoralists’ knowledge of grasslands and livestock grazing will help not only to maintain the biodiversity and economic benefits of less productive semi-natural grasslands, but also to innovatively preserve the traditional pastoral way of life.

The members of the ‘Lendület’ Seed Ecology Research Group of the Centre of Ecological Research followed the vegetation dynamics of artificially created grassland patches for several years. The researchers found that in the course of grassland-restoration the efforts at the beginning pay off: the simultaneous sowing of grasses and forbs in fallow lands leads to the development of species-rich grassland communities and efficient weed control.
The aim of ecological restoration is to recreate something lost or deteriorated. Grassland restoration aims to recreate grassland ecosystems and communities. In many cases recreation of the original ecosystem is not a possibility, but restoration still can help to cover landscape scars created by human activities. Restored grasslands not only improve landscape aesthetics but offer many different ecosystem services as well (e.g., forage for the livestock, nectar for pollinators, effective carbon capture and storage, and soil erosion control).
When grassland restoration is done with seed sowing, the success of restoration depends on many factors, such as the identity of sown species, the timing of sowing, the quantity, quality and proportion of sown seeds. In the current study the researchers aimed to find the best timing to sow grasses and forbs to achieve the highest possible species richness, to enhance forb-establishment and to hamper weed encroachment.
„The matrix of the grasslands is composed by grasses. Previous works found that sowing grass seeds certainly results in a closed grass sward within a few years, and also hampers weed encroachment. That is why grass sowing is preferred in landscape-scale restoration works. But it also has its feedbacks: the new grassland will be species-poor, as the closed grass sward hampers the establishment of other grassland species.” – explained Réka Kiss, the first author of the manuscript published in the Nature- Scientific Reports.
To create species-rich grasslands the use of diverse forb seed mixtures is needed. However, the compilation or production of such seed mixtures requires more efforts (seeds of more species are needed in good quality and high quantity). Due to these reasons diverse seed mixture is less likely to be used in the early stages of restoration. In later stages, however, it will need more effort from the practitioners to secure the successful establishment of species.
„We were curious of the most suitable timing: If we want to sow both grasses and forbs in a fallow for a species rich grassland, which is the time-lag when with the least effort we can achieve the most?” – explained Réka Kiss – „At the beginning of the experiment we created 36 patches in a recently abandoned land. We sow exclusively grass seeds, exclusively diverse forb seed mixture (20 species) or both of them into the patches. When we combined the grass with the forb seed mixture we sown them simultaneously (at the same time), or the diverse seed mixture was sown with a delay of 1, 2 or 3 years.”
Following the development of the patches for several years the researchers found that the best results were achieved when seeds were sown simultaneously, without time-lag. In such patches the species richness of species was the highest, the weeds were less successful and the establishment success of sown forb species was the highest. This is the most cost-effective and most successful method among the studied sowing regimes. If simultaneous sowing is not a possibility, sowing forbs one year later than grasses is still effective. However, after one year the advantage received by grasses cannot be outcome by the forbs, their successful establishment in later stages can be promoted only by active interventions.

Source: nature.com - Co-seeding grasses and forbs supports restoration of species-rich grasslands and improves weed control in ex-arable land - 2022-12-08