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Garden ponds: Hidden gems of urban biodiversity conservation

Urbanization is rapidly transforming landscapes worldwide, becoming a key driver of global biodiversity loss. It often impacts biodiversity negatively by creating selective environments that limit species diversity in urban compared to natural habitats. Amidst this challenge, understanding and enhancing urban blue-green infrastructure is critical.

Garden ponds are small yet significant water features that are increasingly common in urban areas. They offer numerous ecosystem services, like aesthetic purposes, microclimate regulation, and habitats for ornamental species. However, their role in supporting biodiversity is still largely unknown.

A recent countrywide citizen science project called launched by researchers from the HUN-REN Center for Ecological Research in Hungary highlights the potential of garden ponds as crucial contributors to urban biodiversity.

The online survey gathered data from over 800 garden pond owners, uncovering insights into how these small water bodies support various animals, including amphibians and their tadpoles, odonates, and birds. The study also examined the impact of pond features, pond management practices, and urbanization on the occurrence of these animals, shedding light on the role of pond management for wildlife.

"Our findings revealed that key pond features such as pond age, area, aquatic, and shoreline vegetation all have a strong influence on the occurrence of the studied animals. Amphibians and their tadpoles, odonates, and birds were less likely to be present in or at newly installed ponds (0–1 year), which can be due to the lack of vegetation and sediment that could offer hiding and breeding places.

"Aquatic vegetation was positively associated with the presence of tadpoles, odonates, and birds, which indicates the habitat structuring role of aquatic vegetation that benefits biodiversity. Conversely, algaecide addition negatively affected the presence of amphibians and their tadpoles.

"Ponds in strongly urbanized areas had fewer sightings of adult amphibians and their tadpoles, while these types of ponds were visited by more odonates and birds. Despite these challenges, garden ponds emerged as vital refuges for wildlife, hosting a total of 13 amphibian species across the country, and providing critical secondary habitats within urban landscapes," explains Zsuzsanna Márton, first author of the study in Landscape and Urban Planning.

Beyond biodiversity, the study also highlighted the ecological importance of garden ponds and provided actionable insights for urban biodiversity conservation, encouraging thoughtful pond management and design to maximize their benefits.

"Our study demonstrates that citizen science is a powerful tool for urban planning, as it can contribute to gathering valuable data on urban biodiversity and utilize it for more efficient conservation strategies. It could help urban planning by identifying hotspots of aquatic biodiversity or critical areas for the conservation of key groups like amphibians in urban environments.

"Garden ponds might provide important stepping stones, connecting other aquatic habitats in the landscape. Also, participants may become more conscious of environmental issues and their role in them, which might lead to more active engagement in supporting blue-green infrastructure development," says Dr. Zsófia Horváth, the senior author of the study and head of the Biodiversity and Metacommunity Ecology Research Group at the Institute of Aquatic Ecology, HUN-REN Center for Ecological Research.