Award: OCE-1851866

The northwest Atlantic Ocean has warmed more than three times faster than the global ocean. This means that ecosystems along the US coast from North Carolina to Maine have experienced a rate of warming that few other ecosystems have experienced. This project used the warming in this region as a natural experiment to understand how temperature influences the structure and function of marine ecosystems, from plankton to whales. We found that Calanus finmarchicus, the dominant zooplankton species in the Gulf of Maine has declined considerably since 2010. The decline coincided with an increase in smaller plankton species. While plankton have short generation times, both our modeling and observational work suggest that plankton communities respond slowly and that interactions among species (for example, predators and prey) amplify small changes in the physics. We also found that the fish community in the Gulf of Maine is changing. Cold water ecosystems like the Gulf of Maine are famous for their abundance of large-bodied fish like code, while warmer water ecosystems like those further to the south tend to have more small-bodied individuals. We found that while many cold water species are still present, they are smaller, which means that the Gulf of Maine ecosystem likely now functions more like the ecosystem in the Mid-Atlantic Bight (the region from NC to MA). This conclusion is supported by food-web modeling that shows changes in how energy is flowing through the ecosystem. This project contributed to the training of one postdoctoral associate and three graduate students. It also supported the development of a unique curriculum that middle school teachers can use to help their students learn about marine food webs and climate change. Last Modified: 09/05/2023 Submitted by: Andrew Pershing