Combined effects of global warming and microplastic exposure from individual to populational levels of a benthic copepod

Global warming and plastic pollution are two human-induced environmental stressors of concern which affect aquatic organism and ecosystems, but their combined effects are not yet clarified. Furthermore, the microplastics effects at organism level are currently being widely investigated, but the effects at population level, particularly in combination with other environmental stressors such as increased seawater temperatures, are unknown. Therefore, our goal was to assess the combined effects of microplastics exposure and temperature increased in the benthic copepod Nitokra spinipes, at organism level to, and then to further investigate their population dynamics. To do so, we first exposed the harpacticoid copepod N. spinipes to Poly(lactic-co-glycolic) acid (PLGA) microbeads (5µm), at control (22°C) and increased water temperatures (+3°C, as per the RCP8.5-IPCC emissions scenario). First, the effects on N. spinipes individuals were assessed by identifying shifts on the filtration rate, a proxy for energy assimilation. Then, based on the observed filtration rates, we simulated their population dynamics under the projected +3°C, while exposed to microplastics, using an individual-based model implementation of the dynamic energy budget theory (DEB-IBM). All N. spinipes treatments at 25°C had a significantly higher filtration rate [64.1±41.5 nL/indiv/min] compared to the treatments at control temperature (22°C) [10.4±9.6nL/indiv/min]. Our results further indicate that at 25°C treatments, exposure to PLGA microbeads at 0.1 Also see: https://micro2024.sciencesconf.org/559246/document