Boreal wetlands have always fascinated me because of how quickly they can change. Seasonal dynamics are strong, and organisms living in these environments must constantly adapt to rapid shifts in temperature, water levels, and food availability. Understanding how species respond to these changes is one of the reasons why I chose to study a particular type of wetland during my PhD: temporary wetlands.
Wetlands are among the most important ecosystems on Earth, yet they are also among the most threatened. Over the last century, more than half of the world’s known wetlands have disappeared due to factors such as drainage, brownification, eutrophication, and climate change. This loss has contributed to declines in many wetland-dependent species, including several waterfowls species—especially those that rely on aquatic invertebrates for food.
For waterfowl, breeding success is a key factor determining population trends. Adults but especially ducklings depend heavily on protein-rich aquatic invertebrates during their first weeks of life, so the availability of suitable feeding habitats is crucial. However, one type of wetland that is often overlooked in research and conservation is temporary wetlands.
Temporary wetlands include habitats such as vernal pools and beaver wetlands. Vernal pools are a type of small and shallow temporary wetland that fill with snowmelt and rain in autumn and winter to reach it maximum water lever and spring to dry out in summer. Beaver wetlands, on the other hand, are created when beavers build dams that flood forested areas or lake shorelines, resulting in new aquatic habitats. Both environments often contain large numbers of aquatic invertebrates due to the abundance of decaying vegetation and the typical absence of fish. These conditions can make them ideal feeding grounds for ducks and their ducklings. Yet despite their potential importance, we still know surprisingly little about how waterfowls use these habitats.
My PhD project aims to fill this gap. The study takes place close to the station in the Evo Natura 2000 area and investigates how aquatic insects and other invertebrates vary over time in temporary wetlands compared with permanent lakes, and how these differences influence waterfowls use.
With the help of two students, Nina Bouland and Dora Guarnieri, we monitored waterfowls and their food resources throughout the breeding season, from mid-April to the end of June. Our study included twenty-one sites: seven lakes, seven vernal pools, and seven beaver wetlands. At each site, we sampled aquatic invertebrates and recorded waterfowl presence. I also used camera traps to monitor bird activity throughout the season.
The results are still being analysed, but some interesting patterns are already emerging. Preliminary observations suggest that vernal pools and beaver wetlands may host relatively high numbers of birds compared with lakes, especially when considering their small size. Vernal pools seem to be particularly important early in the season, just after snowmelt, when aquatic invertebrates are very abundant and females need energy either to recover from migration or to store energy to produce eggs. Beaver wetlands and lakes, in contrast, appear to provide more stable conditions later in the breeding season. It also seems that beaver wetlands are a good habitat later in the season for ducklings to feed and grow. Regarding the vernal pools, we noticed that even though they dry out, all the monitored ones (even the smallest ones) had ducklings when they were still flooded later in the season. We also found that vernal pools tend to have very high overall abundances of macroinvertebrates, while beaver wetlands may support greater invertebrate diversity.
For me, Lammi is almost like a second home. I first came here for a university internship and to do my Master’s thesis, and later lived at the station for a year and a half at the beginning of my PhD. During that time, I became part of a strong and welcoming community that has not only supported my research but also given me lasting friendships. I am therefore very grateful to the Lammi Biological Station Environmental Research Foundation, whose grant made this research possible.
If you want to know more about my works you can check out the POOL project
In collaboration with Martin Bozon, Basile Mateau released also recently this article "Sexual Dimorphism in Dorsal Spot Number and Yellow Surface Area in Fire Salamanders, Salamandra salamandra terrestris Linnaeus, 1758 (Caudata: Salamandridae)"