Effects of Ocean Warming Across the Life Cycle of Bull Kelp

Archived video of the zoom webinar.

Bull kelp (Nereocystis luetkeana) forests have been declining over the last century in some areas of the Salish Sea, particularly those that experience elevated temperatures and low current velocities. Bull kelp have a biphasic life cycle with two very distinct free-living stages: a large diploid sporophyte, which can reach the surface of the ocean, and microscopic haploid gametophytes, which live on the bottom of the ocean. Temperature stress can impact the entire life cycle of bull kelp. In addition to high temperatures, low nitrogen concentrations can be stressful for marine primary producers, yet these stressors often occur simultaneously in temperate marine ecosystems, making it difficult to unravel their effects. Using temperature-controlled experiments in the lab, my research explores the consequences of ocean warming for bull kelp a) gametophyte growth and reproductive success, and b) adult sporophyte blade growth and photosynthetic physiology. In addition, this research explores the combined effects of heat stress and nitrogen limitation on the physiology of bull kelp sporophyte blades.