The impact of the oceanic temperature raise due to climate change might have profound consequences for key components of marine food webs, such as zooplankton. In general, the fate of a species facing a temperature change in its habitat will depend on the coupling among the different thermal sensitivities of key ecophysiological activities. In this regard, thermal windows define the tolerance range of temperature for a given species, and are a good indicator of its vulnerability to changes in habitat temperature. Here, we report preliminary data on short-term responses (1 day) to temperature changes (range from 5ºC to 34ºC) on microzooplankton. We built thermal windows for two heterotrophic dinoflagellates (Gyrodinium dominans and Oxyrrhis marina) and one ciliate (Strombidium sp.) grown for multiple generations at 19ºC. The variables considered were growth, ingestion rates, and growth gross efficiency. The experiments showed the ciliate to be the more resistant to changes in temperature and the one benefiting the most from a rise in temperature. These contrasted responses between ciliates and dinoflagellates, if confirmed for other species, could have profound implications for the structure of marine communities under future climate change scenarios. In the future, we aim to investigate the thermal sensitivity of key ecophysiological activities of zooplankton to long-term (multigenerational) changes in temperature, and to determine how the coupling of these different thermal sensitivities may result in adaptive advantages or disadvantages for a given species.

Association for the Sciences of Limnology and Oceanography Aquatic Sciences Meeting (ASLO 2019), Planet Water - Challenges and Successes, 23 February - 2 March 2019, San Juan, Puerto Rico