Fluctuations in primary productivity and their correlates in the northeast Pacific Ocean

Catherine Pfister

Department of Ecology & Evolution, University of Chicago. https://pfisterlab.uchicago.edu/

cpfister@uchicago.edu

Spatial and temporal variability in the dynamics of seaweed species are critically important to coastal primary productivity. My research in the northeast Pacific Ocean has attempted to understand the sources of variability and its consequences. The Washington state shoreline represents a spatial gradient in wave energy, seawater temperatures, and anthropogenic influences. There is also temporal variability in oceanic indices that can be drivers of variation in primary production, including large-scale indices such as the Pacific Decadal Oscillation. Ecological theory guides us in examining how variability driven by the environment might be beneficial to population persistence or detrimental. Synchronicity in species dynamics through time or space can depress overall mean productivity, while asynchronous dynamics can provide a buffer to overall variability in primary production. When I examine the long-term temporal dynamics of 4 understory kelp species and 2 canopy kelp species on Tatoosh Island, Washington, I find correlates of kelp fitness with environmental drivers. These environmental correlates can switch with trophic interactions and lead to asynchronous dynamics among kelp that may help dampen fluctuations in primary productivity. However, large-scale spatial correlation (a Moran Effect) also exists in canopy kelp species, perhaps increasing their vulnerability to environmental drivers over the seascape.

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