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2023. 09. 29. Mázsa Katalin

Urbanisation generates multiple trait syndromes for terrestrial animal taxa worldwide

More than 50% of the world’s population currently lives in cities, yet cities can be home to significant biodiversity that provides important ecosystem services to urban populations. An international team of researchers, including Andrew J. Hamer, Senior Research Fellow at the Institute of Aquatic Ecology at the Centre for Ecological Research, has shown that urbanisation causes different changes in trait composition between animal groups through a systematic review of databases and publications on six terrestrial fauna groups (amphibians, bats, bees, birds, beetles and reptiles) in 379 cities on six continents. The study was published in Nature Communications.

Although urban environments cause significant habitat loss and alter the spatial structure of the landscape, it is crucial to conserve the remaining urban biodiversity and even increase the role of cities in reducing the current biodiversity extinction crisis. Understanding how different groups of animals respond through their functional traits to the impacts of urban environments worldwide is essential for developing effective strategies to promote biodiversity in urban environments.

Significant progress has been made in understanding the impacts of urbanisation on global biodiversity, there are still many gaps in research. Previous studies has focused geographically on major metropolitan areas in the northern hemisphere and Australia. However, the majority of the areas of greatest biodiversity value are in the tropics and the southern hemisphere, and these areas have been less investigated. Urban landscape structure has largely been characterised by negative indicators such as the proportion of impermeable surfaces, while biodiversity-enhancing indicators such as the proportion and spatial distribution of vegetation cover have received relatively less attention, particularly at the global level. Studies on urban biodiversity have so far mainly focused on plants and birds. Urbanisation also affects other species-rich and functionally important animal groups that have been little studied, such as insects, amphibians, bats and reptiles. Most studies on urban biodiversity continue to focus on taxonomic diversity, despite the growing importance of functional traits in the ecological literature.

In the Nature Communications study, six groups of terrestrial fauna (amphibians, bats, bees, birds, beetles and reptiles) from 379 cities on six continents were reviewed and shown that urbanisation causes taxon-specific changes in trait composition, with traits related to reproductive strategy showing the strongest response. The study results suggest that the impact of urbanisation on functional traits results in a set of four urban traits related to animal mobility and food preference, which can be classified into four types: mobile generalists, site specialists, central foragers and mobile specialists.

Mobile generalists includes taxa such as bats and carabid beetles are highly mobile species with more generalist diets and reproductive strategies that are better able to exploit available resources in urban environments. The urban trait syndrome associated with site specialists was characterised by reduced mobility, increased dietary specialism and a shift towards smaller clutch sizes. These traits are advantageous to species that are reliant on highly localised life cycles, such as amphibians and reptiles. Central place foragers establish a home base location from which they undertake daily movements to forage for additional resources. The taxa that displayed this urban trait syndrome were bees and birds. Mobile specialists are characterised by species that are able to meet their resource needs by being dietary specialists that are highly mobile and can move between spatially isolated food sources without having to return to a central place. Wetland birds can be regarded as mobile specialists, where their distribution is tightly linked to a specific resource (waterbodies), but they have the capacity to easily move between locations when resources fluctuate.

Frogs are site specialists – they are are reliant on highly localised life cycles
(Photo: Shutterstock)

These findings are in contrast to the hypothesis that there is one single global ‘urban trait syndrome’ as a species response to urbanisation. The results therefore reassess previous ideas about ecological community dynamics and biotic homogenisation of urban ecosystems. It is crucial for the survival of different animal groups that conservation and urban development regulations and plans for cities and their environments take into account the different needs of different animal groups, as this may underpin the increasing role of cities in mitigating global biodiversity loss.

Lead photo: Julia Horanyi: An urban wetland that is habitat for species covered by all four urban trait syndromes

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2023. 08. 21. Mázsa Katalin

New study with the involvement of Hungarian researchers calls for urgent action due to halt in the recovery of European freshwater biodiversity

A new study that sheds light on the extraordinary sensitivity of freshwater ecosystems and the long-term negative consequences of human impacts on biodiversity has been published in the most prestigious scientific journal, Nature. The research is based on a comprehensive dataset of 1,816 time series of freshwater invertebrate communities between 1968 and 2020 from 22 European countries, comprising 714,698 individuals of 2,648 taxa from 26,668 samples. Two Hungarian researchers, Dr. Gábor Várbíró from the Institute of Aquatic Ecology of the ELKH Centre for Ecological Research (CER), and Dr. Zoltán Csabai from the University of Pécs (PTE) also took part in the compilation and analysis of the data. Due to the persistent and newly emerging threats posed by climate change, invasive species, and new pollutants, the study calls for an immediate and intensified focus on mitigation strategies to rejuvenate the recovery of freshwater biodiversity.

Freshwater ecosystems hold significant significance in the context of global biodiversity. These water bodies provide habitat for numerous plant and animal species, and they play a crucial role in maintaining food chains and preserving ecological balance. Mitigation measures including wastewater treatment and hydromorphological restoration have historically shown promise in improving environmental quality and supporting the recovery of freshwater biodiversity.

Together with a large international team the study’s first author, Prof. Dr. Peter Haase of the Senckenberg Research Institute and Natural History Museum in Frankfurt and Dr. Ellen A. R. Welti of the Smithsonian’s Conservation Ecology Center in the US analysed a comprehensive dataset of 1,816 time series of freshwater invertebrate communities between 1968 and 2020 from 22 European countries, comprising 714,698 individuals of 2,648 taxa from 26,668 samples. The analysis reveals a plateauing trend in the gains achieved.

714,698 observations of 2,648 species from 26,668 samples were analyzed by the research team. Dr. Gábor Várbíró, one of the Hungarian team members

The study indicates notable increases in taxon richness (0.73% per year), functional richness (2.4% per year), and abundance (1.17% per year) of freshwater organisms. These positive trends were prominent up until the 2010s, after which the recovery rates have significantly slowed down. Alarming patterns emerged in communities located downstream of dams, urban areas, and croplands, where the prospects for recovery appear grim. Moreover, sites experiencing higher rates of warming demonstrated fewer biodiversity gains, underlining the impact of climate change on freshwater ecosystems.

The study underscores the vulnerability of inland waters to a range of anthropogenic pressures, including pollution, urbanization, and the impacts of climate change. Despite past regulatory efforts, including landmark legislations like the ‘US Clean Water Act’ of 1972 and the EU Water Framework Directive of 2000, the researchers emphasize that more needs to be done to counteract the increasing stressors that threaten these vital ecosystems.

The researchers suggest that while the gains witnessed in the 1990s and 2000s could be attributed to successful water-quality enhancements and restoration endeavours, the observed deceleration in the 2010s suggests a diminishing effectiveness of the current measures. These measures led to a significant reduction in organic pollution and acidification, beginning around 1980. Over the past 50 years, these steps have contributed to the containment of wastewater pollution and resulted in improvements in freshwater biodiversity. Unfortunately, as the number and impact of stressors continue to increase worldwide, the improvements resulting from past legislation are lessening and freshwater systems remain degraded in many places. With the persistent and emerging threats posed by climate change, invasive species, and new pollutants, the study calls for an immediate and intensified focus on mitigation strategies to rejuvenate the recovery of freshwater biodiversity.

Biodiversity in river systems from 22 European countries increased significantly over a period from 1968 to 2020 – but this trend has stagnated since the 2010s

The involvement of two Hungarian scientists. Dr. Gábor Várbíró from CER and Dr. Zoltán Csabai from PTE adds a significant layer of expertise to this critical research effort. Their collaboration within the international team has shed light on the status of European freshwater biodiversity and underscored the urgent need for actionable conservation measures.
Dr. Gábor Várbíró said, “Our findings raise a critical alarm for the health of European freshwater ecosystems. The slowdown in recovery rates demands a comprehensive re-evaluation of existing mitigation measures and the implementation of new, adaptive strategies. Time is of the essence, and we must act swiftly to protect these essential ecosystems.”
The study underscores the necessity of a multi-faceted approach, engaging policymakers, scientists, and communities at large, to ensure the long-term vitality of freshwater ecosystems. As Europe and the world face increasingly complex environmental challenges, collaborative and immediate actions are crucial to reverse the trend of stagnating freshwater biodiversity recovery.

Publication
Haase, P., Bowler, D. E., Baker, N. J. … Csabai, Z., Várbíró, G. et al. (2023). The recovery of European freshwater biodiversity has come to a halt. Nature. DOI: 10.1038/s41586-023-06400-1

Photos: Gabriella Bodnár, – Centre for Ecological Research

News

2023. 08. 17. Mázsa Katalin

Small-molecule autocatalysis drives compartment growth, competition and reproduction

With the decisive participation of Eörs Szathmáry, Member of the HAS and Research Professor at the Institute of Evolution of the Centre for Ecological Research, an international team of researchers has achieved a major new breakthrough in the study of the origin of life. The paper was published in Nature Chemistry, one of the world’s leading chemistry journals.

The discipline of systems chemistry deals with the analysis and synthesis of various autocatalytic systems and is therefore closely related to the study of the origin of life, since it investigates systems that can be considered as a transition between chemical and biological evolution: more complex than simple molecules, but simpler than living cells.

Tibor Gánti described the theory of self-replicating microspheres as early as 1978. These still lacked genetic material, but concealed within their membranes an autocatalytic metabolic network of small molecules, isolated (compartmentalised) within their membranes. As the autocatalytic process takes place, the membrane-building material is also produced, leading to the division of the sphere. This system may appear to be a living cell, and although it lacks genetic material, this can only be verified experimentally. These microspheres can be considered as ‘infrabiological’ chemical systems, since they do not reach the level of biological organisation, but they exceed the complexity of normal chemical reactions.

Years ago, we started to think about the possibility of experimentally realising the process whereby the growth of a small molecule metabolic network leads to the growth of the compartments that enclose the network, to the effect that they can divide. Already Tibor Gánti has described that one of the most promising candidates for this system is the formose reaction, an autocatalytic sugar-producing reaction that consumes formaldehyde and involves the circular transformation and propagation of glycolaldehyde molecules. The reaction does not require enzymes.
The experiment on which the study is based was carried out in the biochemistry laboratory of the École Supérieure de Physique et de Chimie Industrielles (ESPCI) in Paris by Professor Andrew Griffiths and his colleagues. The experiment involved creating tiny water droplets in an oil medium that did not fuse and therefore acted as artificial cells. Some of the ‘cells’ were given glycolaldehyde as an autocatalyst (in addition to formaldehyde as a nutrient), others were not. In the former group, the formose reaction was triggered and, by osmosis, it sucked water away from compartments that did not contain glycolaldehyde. This allowed them to grow and to divide under external influence. Many researchers have suggested that before the emergence of regulated cell division, the initial cells divided in response to external influences such as turbulent flow.

The significance of this study is that we are the first in the world to show that the operation of a network of small-molecule autocatalytic reactions, without genetic material and enzymes, leads to the growth and division of compartments, i.e. the formation of new generations. This has never been demonstrated before, so the result is fundamental to the experimental verification of the principles of systems chemistry and points the way forward in the study of the origin of life.

News

2023. 07. 25. Mázsa Katalin

Continuous precipitation loss causes severe damage to the diatom assemblages in large 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 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.

Reimeria sinuata: one of the diatom species indicating the effects of drought in 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 ELKH Centre for Ecological Research (CER) and Babeș-Bolyai University (BBE) in three recent papers have described the effects of twelve invasive plant species with different traits on vegetation (Fenesi et al. 2023), pollinator communities (Kovács-Hostyánszki et al. 2022), and the traits of pollinating insects (Szigeti et al. 2023). During their field studies they assessed and compared the plant and pollinator communities of invaded and semi-natural habitats in Hungary and Romania. In order to facilitate proper comparisons and conduct detailed exploration, the researchers employed uniform field methods while utilizing diverse ecological indicators, ranging from the height of indigenous vegetation, honeybee abundances, depth of flowers to tongue length of pollinator insects.

Bees and other pollinator species play an extremely important role in most terrestrial ecosystems, including agriculture. Increasingly, studies report the drastic decline of pollinating insects, one reason being the reduced availability of their food resources. The strong spread of invasive species is one of the five most important causes of biodiversity loss, that is why the Invasion Biology Division was established under the leadership of the Ecological Research Center within the National Laboratory for Health Security, where researchers investigate the complex effects of invasion. Where invasive plant species appear and are able to spread, they inundate and dominate the given area, reducing diversity and making habitats more homogeneous. In many cases, they also reduce the range of available flowers, thus helping some compatible pollinator species while displacing the food resources of others from the landscape. In general, it can be stated that the impacts of invasive plant species on native vegetation and pollinator insects are often varied and dependent on their specific traits.

Based on the research results, there is no universal effect of plant invasion, except for a few general patterns there are differences among invasive plant species in almost every ecological indicator studied. Perhaps the most important message is that as many invasive plant species and traits as there are, there can be a variety of effects on invaded plant-pollinator communities. The three publications highlight that the cover of invasive plant species strongly influences the composition, diversity, and height of the remaining native vegetation, among other factors. As the invasive plant species displaces native plants in a given area, fewer of the original or potential communities remain. Perennial invasive plant species have an even stronger negative impact on flower availability and pollinators than annual species. This is likely due to their stronger invasive capacity, dominance, different growth and flowering strategies, and presence in later successional stages of habitats. Timing is extremely important in plant-pollinator systems. Invaded areas are similar to crop fields such as rapeseed or sunflowers: during their blooming period, they provide significant amounts of food for the pollinating insects, while beyond of their flowering period, these areas are extremely poor in resources of pollinators. Where invasive plant species appear, they eventually become dominant. They cover the area with green vegetation mass for most of the year, but only bloom for a short period of time. As indicated by the studies, natural areas have more and more diverse resources along the year. The researchers also found important and interesting relations when comparing the traits of invasive flowers and the traits of wild bees. For example, the sites invaded by two invasive species with deep flowers had more long-tongued and also larger-bodied bees, while a species with shallow flowers had more smaller-bodied bees. This indicates a strong size determination between flowers and their pollinators, meaning that the invasion of a particular trait (such as deep flowers in invasive plants) affects the functional characteristics of the remaining pollinator community in the invaded area (i.e., only long-tongued pollinators that can feed on deep flowers will remain).

Proper nature conservation management of (semi)natural habitats and effective control of invasive plant species are important for the protection of pollinators, but some invasive plants can also provide valuable foraging resources for pollinator insects. Therefore, instead of uniformly eradicating all invasive species, it is recommended to consider the best approach on a case-by-case and location-specific basis, taking also into account the needs of protected pollinator insects. For example, efforts to combat plant invasion could incorporate the nutritional requirements of pollinators. Some of the costs associated with invasive plant eradication could be redirected towards providing alternative nutrition sources, such as sowing native seed mixes in or in the neighborhood of invaded areas. Overall, the factors and impacts important in the plant-pollinator systems are complex and interrelated, hence further detailed studies are needed to uncover the specific relationships between species and to develop effective conservation solutions.

Publications:

Fenesi, A., Botta-Dukát, Z., Miholcsa, Zs., Szigeti, V., Molnár, Cs., Sándor, D., Szabó, A., Kuhn, T., Kovács-Hostyánszki, A. (2023). No consistencies in abundance-impact relationships across herbaceous invasive species and ecological impact metrics. Journal of Ecology. DOI: 10.1111/1365-2745.14085

Kovács-Hostyánszki, A., Szigeti, V., Miholcsa, Zs., Sándor, D., Soltész, Z., Török, E., Fenesi, A. (2022). Threats and benefits of invasive alien plant species on pollinators. Basic and Applied Ecology, 64:89–102. DOI: 10.1016/j.baae.2022.07.003

Szigeti, V., Fenesi, A., Botta-Dukát, Z., Kuhlmann, M., Potts, S. G., Roberts, S., Soltész, Z., Török, E., Kovács-Hostyánszki, A. (2023). Trait-based effects of plant invasion on floral resources, hoverflies and bees. Insect Conservation and Diversity. DOI: 10.1111/icad.12640

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