In the oceans, zooplankton play a critical role as the link between primary producers (phytoplankton) and upper trophic levels (fish). Their functions, including nutrient recycling and carbon export to the deep ocean, make them essential for the ecosystem dynamics. In the current climate change scenario, the escalating frequency of marine heatwaves poses further threats to zooplankton because the rapid and substantial temperature increases may exceed their physiological limits, resulting in a significant risk to marine zooplankton populations. Despite its relevance, limited attention has been given to the effects of marine heatwaves on planktonic organisms.
Our research proposal, ZOOHEAT, addresses this critical gap by investigating the capacity of marine zooplankton to withstand heatwave events. Recognizing that extreme events can occur within- and between-generational time scales for short-lived organisms like zooplankton, our approach combines short-term studies with longer-term exposed populations to mimic seasonal thermal changes. We aim to unravel how the effects of heatwaves on zooplankton are influenced by previous thermal history and resource concentration. This aspect is relatively unexplored, yet essential for comprehending the vulnerability and resilience of zooplankton to heat events.
The project focuses on selected microzooplankton (ciliates and dinoflagellates) and mesozooplankton (copepods), employing a laboratory- oriented approach to study their physiological vulnerability to heat events, considering carry-over effects along their thermal history as well as the influence of food availability. The general objective is to investigate the impact of heatwaves on the ecophysiological responses and vulnerability thresholds of marine zooplankton, with specific objectives focusing on protozoan and copepod populations. Our innovative research seeks to enhance our understanding of the mechanisms determining a species' ability to persist under heat events based on previous thermal history and resource limitation.
While ZOOHEAT is a basic science research project, the knowledge gained is anticipated to contribute significantly to refining ecological and biogeochemical models. Ultimately, this enhanced understanding will empower society to better forecast and address future challenges in the marine ecosystem, underscoring the project's potential for high impact at national and international levels.