Temperature is one of the most prominent climate-change variables affecting marine zooplankton activity and distribution. The impact of warming on zooplankton depends not only on physiological sensitivity, but also on the temporal scale of exposure and the species acclimation capacity. Warming events of a few days or weeks of duration will mainly impact at the intragenerational level, while longer-term warming will reflect on multigenerational responses. In this study, we compare the effects of +3 and +6ºC thermal stress on the vital rates of the copepod Paracartia grani at short (2 and 7 days, acclimation response) and long (>10 generations, multigenerational response) time scales. P. grani showed high phenotypic plasticity after 2-d exposure, increasing feeding and egg production rates. This acute response, however, declined quickly and after 7 days of exposure the enhancement of physiological rates was still positive but of lesser magnitude (Q10 <2). Multigenerational rearing at the tested temperatures resulted in a further reduction of the copepod response to temperature and the apparent loss of thermal effects, implying further adaptive compensation processes. The metabolic costs of the thermal responses, estimated as the copepod gross-growth efficiency, did not appear to be influenced by temperature, suggesting the species has high thermal tolerance

This research was funded by Grants [CTM2017-84288-R and PID2020-118645RB-I00] by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe.”

ASLO Aquatic Sciences Meeting, Resilience and Recovery in Aquatic Systems, 4-9 June 2023, Palma de Mallorca, Spain.-- 1 page, figures