A trophic cascade causes unexpected ecological interactions across the aquatic-terrestrial interface under extreme weather

Beskrivning

Understanding how aquatic trophic cascades can affect organisms across the aquatic interface by changes in water quality becomes a pressing issue under extreme weather, when terrestrial organisms such as bees have increased physiological demands for water. In a novel field experiment combining terrestrial and aquatic mesocosms, we aimed to test how changes in water quality induced by an aquatic trophic cascade affected foraging and growth of bumblebee colonies. While we expected fish predation to reduce top-down control of zooplankton on phytoplankton and thereby, indirectly, induce increased growth of toxic cyanobacteria, we instead found the trophic cascade to induce the formation of algal surface mats that bumblebees used to access water under a severe heat wave and drought. This access to water was associated with higher bumblebee colony reproduction, growth and weight compared to control colonies. We also found marginal effects on oilseed rape yield, but surprisingly with higher yields in the control treatment where bumblebees could not access water. Our results provide new insights on how aquatic trophic cascades can lead to ecological interactions across the aquatic-terrestrial interface facilitated by climate change and highlights the importance of water for the fitness of terrestrial ecosystem service providers under extreme environmental conditions.

Period	2022 maj 17
Evenemangstitel	Swedish Climate Symposium 2022
Typ av evenemang	Konferens
Plats	Norrköping, SverigeVisa på karta