Two hallmarks of environmental change in oceans is that first, many aspects of the environment change concurrently. For example, while oceans will warm, the nutrients available for phytoplankton growth in many regions will drop. Second, projections of future environments carry high uncertainty. For example, projections of global average sea surface temperature changes in the coming decades span ~4°C, with uncertainties in local projections being even higher. Because of these two characteristics of ocean change, our understanding of organismal responses to it must be applicable over a wide range of multidriver environments.  I will present experimental results of the plastic (short term) and evolutionary (long term) growth of a model diatom in 20-25 different temperature x nitrate environments, with each driver present as a gradient at each level of the other driver, also known as a fully factorial experiment. We show that the ability to respond to warming on all time scales is a function of initial nitrate availability, with the optimum temperature for growth (T_opt) being a saturating function of nitrate availability in the short term. In the longer term, the ability to adapt to high temperatures by increasing growth and shifting T_opt upwards depends on nitrate availability, and we identify the critical concentration of nitrate needed for adaptation to warming in otherwise ideal environments. Finally, we demonstrate that adaptation is linked to changes in common markers of stress, such as internal pools of reactive oxygen. We also discuss trends in changes in ecologically-important traits such as cell size across the full range of multidriver environments. The resourcing and logistics of fully-factorial multidriver experiments can appear substantial, but we strongly advocate for doing them where possible. Because of this, I will go over the advantages and limitations of laboratory experiments with enough environments to generate response surfaces  relative to experiments that use a smaller number of environmental scenarios.

Tutorial/Invited: Tutorial

Primary Presenter: Sinéad Collins, University of Edinburgh (s.collins@ed.ac.uk)

Authors:

Emma Forss, University of Norway  (efo059@uit.no)

Toby Linley-Adams, University of Edinburgh  ()

Mridul Thomas, University of Geneva  (mridul.thomas@unige.ch)