What doesn’t kill you makes you stronger: fear of predation widens the thermal niche of the harmful algal bloom species Phaeocystis globosa

Le résumé fourni par la source

Abstract High temperatures inhibit Phaeocystis globosa colony formation by reducing synthesis and enhancing degradation of colony mucus components, but this insufficiently explains the occurrence of colonial blooms in tropical summers. P. globosa enhances colony development as a defensive response to zooplankton grazing risks, playing key roles in their success in marine systems. To evaluate whether predation risks modulate thermal responses, P. globosa grown alone and exposed to grazing cues associated with ciliates and copepods were maintained at temperatures ranging from 13 to 30°C. P. globosa exposed to both grazing risks exhibited defensive responses, including higher colony abundances, greater colony diameters and higher colonial cell abundances. Solitary cells of P. globosa exposed to grazing cues grew at 30°C, whereas non-exposed cells failed to survive at this temperature. Grazer-induced P. globosa developed colonies at 15–30°C, whereas colonies without induction were restricted to 17–25°C. Thermal performance curve modeling revealed that exposure to grazing cues significantly increased the critical thermal maximum by nearly 5°C. Fear of predation increased the tolerance of P. globosa to high temperatures, enabling colonial blooms to grow at lower latitudes and potential reducing vulnerability of P. globosa blooms to climate warming. These findings emphasize the importance of considering fear effects to accurately understand impacts of climate change on phytoplankton dynamics.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.