Resurveys of zooplankton metacommunities in ponds and wetlands

In the summer of 2025, we began our resurvey field campaign in Belgium, where we resampled ponds that were sampled by our colleagues at KU Leuven.

The sampling team, comprised of Minghua Shen, Alban Sagouis, Irina Kalmanova and Leonie Schilling and under the leadership and supervision of Prof. Jonathan Chase, spent a total of 6 weeks collecting samples from ponds across Belgium. They received additional support from hydrobiologists Yuhan He and Kanshun Zhao from the Faculty of Biological and Environmental Sciences at the University of Helsinki.

Due to the very seasonal nature of the zooplankton life cycle, it was important that sampling take place in July and early August in order to accurately replicate previous studies.

Belgium was chosen for this field season as there have been three different studies conducted in the past by scientists at the KU Leuven that documented the characteristics of the ponds and the zooplankton living within these ponds. Most importantly, the data that was then collected included data on how many of each species were present per unit of water (quantitative dta). This information is necessary in order to be able to assess change across time. Furthermore, the data that was collected as part of these studies included information about the pond water such as the temperature, pH, nitrogen and phosphates. This information gives scientists a basis of comparison to be able to assess changes that have taken place inside the pond.

Ponds were grouped into clusters of at least three in order to constitute metacommunities. In some cases, the clusters were comprised of ponds that were previously sampled at the same time. In other cases, clusters had to be created from ponds that constituted part of different historical sampling campaigns. This was due to many ponds having dried up or converted to farmland.

2025 turned out to be a historically dry summer, due to very little rain having fallen in the spring. When the team arrived in Belgium, they were surprised to find how many ponds had completely dried up. But while some ponds had clearly dried up this year, many had already been drying up and becoming overgrown over many years.