Award: IOS-1557868

Intellectual merit: Coastal invertebrates, animals such as mussels, sea snails and seastars, inhabit some of the harshest environments on the planet and understanding how these animals cope with changing environmental conditions is crucial to predicting, and potentially ameliorating the impacts of climate change. Physiological studies exploring the sensitivity of marine invertebrates to altered conditions of temperature, salinity and ocean pH have provided new tools in this regard. But often these studies are conducted under controlled laboratory conditions that may have little to do with what animals experience in the field. For example, studies conducted under constant conditions of temperature provide useful benchmarks, but may not be reflective of the actual environments where water temperatures are constantly changing. One of the biggest gaps in our understanding is how intact assemblages- groups of species which eat one another, and compete for food and other resources- are likely to respond to novel environmental conditions posed by climate change. Our study explored the interactions of three drivers on the mussel Mytilus: food availability, water temperature, and the presence of predatory snails. This last driver is particularly understudied, but evidence suggests that the simple presence of predators, the ?fear of being eaten? can have physiological consequences comparable to fairly large changes in temperature. Our approach used a model experimental system which exposed animals to either ambient water temperatures (which constantly change over the course of a day) or elevated temperatures comparable to those posed by climate change in the Gulf of Maine, which is warming faster than 99% of other large bodies of water on the planet. We also altered food availability as well as exposure to water-borne chemical cues from predatory dog whelks. We measured whole organism responses including growth and accumulation of reproductive tissue, as well as biochemical markers of metabolic stress. Our results show that exposure to predators can have an over-riding physiological effect on production of reproductive tissue, but that the magnitude of this response varies with temperature and food availability. In contrast, temperature played a primary role in determining the amount of body (somatic) tissue, but that the influence of predator risk depended on food levels (and vice versa). These results provide insights into how this economically and ecologically important marine animal is likely to respond to changes in environmental temperature, and strongly cautions that experiments that ignore potential biological interactions such as exposure to predators may not always yield biologically realistic results. Broader impacts: This project provided support to high school students from underrepresented groups- often the first member of their family to attend college- to actively participate in marine science research using a tiered mentoring model. The effort built on an ongoing collaboration (Beach Sisters) between the Northeastern University Marine Science Center and Girls Inc. of Lynn, MA an underserved, environmental justice community to develop STEM literacy and to provide a pathway to academic studies and careers in marine and environmental sciences. This Beach Sisters Fellow trains and mentors six high school Peer Leaders who, in turn, become mentors to elementary, middle school, and other high school youth, supporting a pipeline that engages girls and young women in careers in science. We expanded this pipeline to include undergraduate and graduate students. For two years of the project (2017-2018), the project PI (Helmuth)?s lab hosted one of the Beach Sisters Peer Leaders as a high school intern in the summer following her senior year, prior to her entering college (both students were first-generation college students). These young women conducted independent research under an undergraduate student who in turn was supervised by the project PI and by graduate students working on this project. Together the teams participated in the research described above, and also conducted independent research looking at physiological performance of coastal snails (in 2017) and coastal fish (2018). Both teams produced manuscripts that are in the process of being prepared for a submission to a scientific journal, and members from each team participated in scientific conferences. This project also supported three female graduate students, including dissertation chapters directly related to this project. At Sonoma State University, the PI (Zippay) trained over a dozen undergraduates on various molecular and physiological techniques with many of them being first-generation college students. In addition, there were two summer REU students (Summer 2017 & 2018) who assisted on the setup, running of the experiment, processing the samples and running the analysis. One of the REU has since graduated from Sonoma State with his Masters and has gone onto a PhD program. The other undergraduate is now a graduate student in my research lab and has presented at a scientific conference and plans to finish his thesis in another semester with the anticipation of publishing our results. This project has also supported two female master graduate students, including their thesis which has been published. Last Modified: 07/24/2020 Submitted by: Brian Helmuth