Kelp Forest Conservation & Restoration

​​Kelp are giant brown algae that form vast underwater forests in coastal oceans, creating essential structural habitat and fixing a tremendous amount of carbon. Kelp forests are declining rapidly in response to ocean warming, with more than one third of kelp forests in decline globally. In Washington’s Puget Sound, bull kelp (Nereocystis luetkeana) forests have declined by more than 60% in the warmest areas. In California, kelp declines were widespread following the 2014-2016 marine heatwave. My research aims to improve our understanding of the physiological responses and susceptibility of kelp forests to ocean warming. One major question is: how we can enhance kelp forest resilience in a changing ocean? Ultimately, the goal is to conserve and restore kelp forest ecosystems.

Kelp have a life cycle with two very distinct stages: macroscopic adults (called sporophytes) and microscopic early life stages (gametophytes), which can be cultivated in the lab. Using temperature-controlled lab experiments, my research team grew bull kelp gametophytes from 8 different populations across 7 different temperatures and 2 nitrogen levels, identifying critical thermal limits for survival and reproduction of bull kelp (Weigel et al. 2023). We also tracked seawater bottom temperatures at the same sites to understand when and where the environment may exceed the thermal tolerance limits for bull kelp growth and reproduction. We also studied the thermal tolerance of adult bull kelp and sugar kelp. For both species, the warmest temperature (21°C) was deleterious to blade growth and metabolism (Fales et al. 2023). Studies with both microscopic gametophytes and adult sporophytes demonstrated that high temperatures were more physiologically stressful than low nitrogen concentrations. My lab will continue to investigate the physiological and genomic responses of marine macroalgae to climate change stressors.