Kelp growth data from seasonal global change experiments examining the effects of seasonal variation in light availability and nutrients on the response of three high-latitude kelp species

This kelp growth dataset results from two, month-long global change laboratory experiments conducted in Sitka, Alaska from February 12 to March 18, 2020 ("winter" experiment) and August 15 to September 16, 2020 ("summer" experiment). These experiments were used to tease apart the effects of seasonal variation in light availability and nutrients on the response of three high-latitude kelp species (Macrocystis pyrifera, Hedophyllum nigripes, and Neoagarum fimbriatum) to pH and temperature. Experimental controls were designed to approximate current environmental conditions in Sitka Sound, and treatments were based on projected end-of-century scenarios of ocean acidification (OA) and warming (OW) for this region. At the end of the experiments, the investigators assessed the seasonal impact of OW and OA on kelp growth rates, thallus nitrogen content, and carbon acquisition strategy based on thallus δ13C values. Finally, to test whether kelp palatability was impacted by future warming and acidification, tissue of H. nigripes and N. fimbriatum grown during the experiments was used to perform feeding assays with a common kelp forest consumer.

These experiments were performed to improve our understanding of how global change will alter marine primary producer resources by integrating natural variation in environmental drivers. This project was overseen by Dr. Kristy Kroeker and her Ph.D. student Lauren Bell, both at the University of California Santa Cruz. Experiments took place in the basement laboratory at the Sitka Sound Science Center in Sitka, AK. This work was supported by the National Science Foundation (OCE-1752600), the David and Lucile Packard Foundation, the North Pacific Research Board's Graduate Student Research Award (1748-02), the UCSC Physical and Biological Sciences 2019 Future Leaders in Coastal Science Award, the Seymour Marine Discovery Center's Student Research and Education Award, and the California State University Monterey Bay Undergraduate Research Opportunities Center.