Miss Kindall Murie1,2, Dr. Aaron Ninokawa1,2, Mr. Ross Whippo3, Dr. Emily Carrington1,2
1University of Washington, Seattle, United States, 2Friday Harbor Laboratories , Friday Harbor, United States, 3University of Oregon , Eugene , United States
Canopy-forming kelps modify local seawater chemistry through metabolic processes (photosynthesis/respiration) causing both pH and dissolved oxygen (DO) to differ from the surrounding waters outside the kelp forest. This change in chemistry may serve as potential refugia from climate stressors like ocean acidification and hypoxia. However, there are few observations on how local hydrodynamic conditions limit the capacity for kelp metabolism to alter the local chemical environment. To better understand how flow influences a kelp forest’s ability to change its chemical environment, we studied a bull kelp (Nereocystis luetkeana) forest in the Salish Sea (USA), an inland sea with dynamic tidally-driven currents. By taking advantage of natural and predictable variation in local hydrodynamic conditions, we captured changes in chemistry both spatially and temporally under a wide range of currents. We found that the largest changes in chemistry occurred in the kelp canopy during periods of high light and low flow. Further, the average daily range in pH and DO was larger in the kelp canopy compared to both surface measurements outside the kelp and benthic measurements below and outside the kelp. Within the kelp canopy, average day-night differences in pH and DO differ due to variations in local hydrodynamics. Although the changes we observed were consistent with a kelp metabolic effect, the magnitude of changes differed greatly with the direction and magnitude of tidal flows during the day. Our results highlight how hydrodynamic conditions play a prominent role in constraining the ability of kelp forests to modify their local chemical environment.
Presentation Slides – Kindall Murie
Biography:
Kindall Murie is a doctoral candidate in the Biology Department at the University of Washington.
