MEPS 403:13-27 (2010)  -  DOI:

Scaling giant kelp field measurements to regional scales using satellite observations

Kyle C. Cavanaugh1,*, David A. Siegel1,2, Brian P. Kinlan3, Daniel C. Reed3

1Institute for Computational Earth System Science, 2Department of Geography, and 3Marine Science Institute, University of California, Santa Barbara, Santa Barbara, California 93106-3060, USA

ABSTRACT: Little is known about the local to regional scale variability in biomass and productivity of many subtidal ecosystems, as appropriate field surveys are both time and labor intensive. Here, we combined high-resolution satellite imagery with aerial photos and diver sampling to assess changes in giant kelp Macrocystis pyrifera canopy cover and biomass along a ~60 km stretch of coastline in the Santa Barbara Channel, California, USA. Our objectives were to (1) develop new methods for estimating giant kelp canopy cover and biomass using satellite imagery, and (2) assess temporal changes in kelp forest biomass across multiple spatial scales. Results of the satellite kelp cover classification compared very favorably with near-coincident high-resolution aerial camera surveys (r2 = 0.90). Monthly diver observations of biomass for fixed plots at 3 kelp forest sites were strongly correlated with satellite determinations of normalized difference vegetation index (NDVI) signals (r2 = 0.77). This allowed us to examine variation in giant kelp biomass across multiple spatial scales (pixel, plot, site, and region). The relationship between plot scale (40 m) changes in biomass and remote assessments of site scale (~1 km) changes varied among sites and depended on the relative location of the plot and the size of the kelp forest at each site. Changes in biomass among sites were well correlated with each other and with the aggregated regional (~60 km) total. Linking field measurements of giant kelp biomass made on a plot scale with regional estimates made by satellite facilitates an understanding of the regional patterns and drivers of biomass and primary production of giant kelp forest ecosystems.

KEY WORDS: Scaling · Remote sensing · Spatial and temporal variability · Giant kelp · Satellite data

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Cite this article as: Cavanaugh KC, Siegel DA, Kinlan BP, Reed DC (2010) Scaling giant kelp field measurements to regional scales using satellite observations. Mar Ecol Prog Ser 403:13-27.

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