Following his research in Europe and Uruguay, ecologist David Cunillera-Montcusí has now joined the Biodiversity and Metacommunity Ecology Research Group at the Institute of Aquatic Ecology of the HUN-REN Centre for Ecological Research (HUN-REN CER). Supported by the European Union's Marie Skłodowska-Curie program, his research aims to investigate the impact of fragmentation of aquatic habitats on biodiversity. In the experiments, he and his colleagues will model the behaviour and resilience of communities living in small ponds with varying levels of connectivity and salt concentrations, as well as different degrees of fragmentation, using 200-liter water tanks known as mesocosms.
Due to climate change and human destruction of nature, habitat networks are deteriorating worldwide: areas inhabited by or suitable for biological communities are decreasing, becoming increasingly fragmented, and even disappearing entirely in many places, resulting in a drastic impact on biodiversity. Aquatic habitats may be even more at risk. The research group at HUN-REN CER investigates the impact of human activities on natural habitats, as the conservation significance of these studies is immeasurable.
However, there is still limited knowledge about how precisely the decline of biological communities occurs due to the loss of connections between habitats as well as changes in both biotic and abiotic conditions, such as the increase in freshwater salinity. David Cunillera-Montcusí aims to investigate this through experimental and model-based research.
David Cunillera-Montcusí, ecologist, working in the Biodiversity and Metacommunity Ecology Research Group with the support of the European Union's Marie Skłodowska-Curie program.
"In my previous research, I primarily investigated how human activities disrupt the functioning of freshwater ecosystems and how landscape-scale characteristics influence their resistance to disturbances. For example, during my doctoral work, I examined how densely situated and interconnected small ponds support the regeneration of nature after forest wildfires," says the ecologist, who previously worked at the University of Barcelona and has collaborated with Hungarian researchers in several studies.
In recent years, Cunillera-Montcusí has primarily investigated the increase in salinity levels in freshwater habitats, known as the "freshwater salinization syndrome," which often serves as an indicator of human disturbance and, at the same time, is a significant cause of decreased biodiversity. The increase in salinity, for example, is a consequence of agricultural and industrial activities or mining. Obviously, salinization affects all members of aquatic communities, as they have adapted to lower salt concentrations. Some species respond poorly to this disturbance and disappear, triggering cascade-like processes within the entire community, which can lead to habitat deterioration or even collapse. David Cunillera-Montcusí has found that the behaviour of small ponds scattered in the landscape effectively models the response of larger natural waters to human disturbances.
"While my previous research primarily focused on small ponds, the mechanisms we've uncovered apply to all types of aquatic habitats. My colleagues and I strive to understand how the structure and distribution of habitats in certain regions can help communities become more resilient to external disturbances. We have observed that resilience doesn't necessarily require large, contiguous habitats. It can also be achieved by preserving many small but well-connected habitats. The more effectively these habitats 'communicate' with each other, the less they are affected by external disturbances," continues the researcher.
As part of his research at HUN-REN CER, David Cunillera-Montcusí will experimentally model the behaviour and resilience of communities living in small ponds with varying levels of connectivity and salt concentrations, as well as different degrees of fragmentation.
"We will use the Institute’s numerous 200-liter water tanks known as mesocosms to simulate small ponds. We will introduce various organisms into them, set their salt concentrations at different levels, and through their placement, we can influence their connectivity with the other mesocosms. Our aim is to quantify the impact of these factors. For example, it may turn out that communities living in mesocosms adjacent to many other habitats exhibit greater resilience to increasing salt concentrations," explains Cunillera-Montcusí.
Drone footage of mesocosms (200-liter experimental water tanks).
As another part of the research, they will analyse datasets collected from the temporary soda pans of Seewinkel in Austria, spanning several decades, and compare them with satellite images of the landscape. Through this approach, they also aim to find answers regarding how landscape-scale structure and habitat connectivity affect changes in biodiversity and resilience. As the researcher explains, analysing data from real natural communities and isolating the effects of various factors is always more challenging than designing experiments themselves. However, this approach is crucial as it is the only way to precisely understand the highly complex functioning of real ecosystems. Additionally, theoretical ecological modelling is also a part of the research. The results of these studies can reveal which areas and types of habitats should be the focus of conservation efforts.
"It may emerge that central habitats that are connected to many other habitats need the highest-level protection. This way, even if we lose certain peripheral habitats, we can preserve a significant portion of biodiversity. This is important for the optimization of conservation efforts," argues the ecologist.