Kelp responses to temperature at 5-10 meters depth at three locations along the California coast from September to December 2016

Giant kelp (Macrocystis pyrifera) is a globally distributed foundation species with seasonal fluctuations in abundance in response to local nutrient levels, storm intensity, and ocean temperatures. In this study, we examined individual and population level responses of early life history stages (zoospore settlement, survival, and gametogenesis) to increased temperatures to determine the capacity for temperature-tolerant individuals to allow adaptation in a changing climate. We collected fertile M. pyrifera sporophyll blades from three sites along the California coast (Los Angeles, Santa Barbara, Monterey Bay) and induced zoospore release in the lab. Spores settled on microscope slides at three treatment temperatures (16º, 20º, 22º C), matured for 21 days, and were imaged weekly to determine settlement, survival, and maturation success. On average, individuals from all sites showed lower rates of settlement and maturation in response to increasing temperature.