Award: OCE-1947965

One key problem facing scientists is predicting the fate of the biota under rapid climate change, a topic that has received less attention in marine than terrestrial species. This project examined roles of phenotypic (within a generation) plasticity and genetic adaptation (across generations) on the thermal performance of dominant copepod species, which are key components of the diet of estuarine forage fish along the Northwest coast of the USA.

Because of travel restrictions due to the Covid pandemic, we had to adapt our plans. This included devoting attention to sleuthing the published literature on thermal performance. We published two meta-analyses on the subject. One demonstrating a positive correlation between upper thermal tolerance and ambient temperature; that is, animals at warmer temperatures show higher upper thermal tolerances. However, this higher thermal tolerance  comes at the cost (a tradeoff) of lower phenotypic response to warming. Thus, animals at lower latitudes are more vulnerable to warming when the temperature increases beyond the optimal value.  The second meta-analysis shows, counterintuitively, a larger divergence in thermal tolerance across populations in marine species than terrestrial or freshwater ones. This suggests a larger  buffer for mitigating effects of warming in marine species relative to terrestrial and freshwater ones. 

We also carried experimental studies that demonstrated that in short-lived copepod species (generation times much less than the annual temperature cycle), the seasonal thermal response is likely underlain by genetic adaptation that buffers the effects of warming. The implication from this study is that genetic adaptation should be considered when predicting the vulnerability of species to warming.  Another study also demonstrated strong copepod resilience when copepod  early stages are exposed to highly elevated, but short warming events. The implication is that carryover effects of exposure to episodic events of warming are not deleterious.    

A third set of experimental studies looked at the effects of prolonged adaptation (more than 100 generations) on the foraging ability of copepods. A key finding is that attack rates of warm-adapted copepod decrease with increasing temperature. This, in turn leads to stabilizing dynamics with phytoplankton prey, but a lower copepod/phytoplankton ratio. This latter result suggests lower ecosystem services under warming in the form of lower food availability for forage fish. 

This project trained three undergraduate students, one M.S. student, one Ph.D. student, and one postdoctoral investigator. The students and the postdoctoral investigator carried out experiments, received  professional development and mentoring, published their work, and disseminated their research across scientific and lay audiences. The two graduate students and the postdocs are currently fully employed in STEM fields. The undergraduate students are finishing degrees or employed in STEM fields. 

We also established collaborations with members of the Research Network on Evolution in Changing seas and with researchers at the University of Quebec, Rimouski, that allowed us to expand our work beyond the original scope of the proposed research.

Our work has provided novel insights to inform predictions of the fate of the marine biota under climate change and trained a cadre of students in tackling problems on the response of the biota to global change stressors. Our work has been disseminated through peer-reviewed publications, through social media, and presentations to lay (K-12) audiences, and expanded our network of collaborators.

 

 

Last Modified: 09/29/2024
Modified by: Hans G Dam