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Boyce et al. reply

Abstract

Replying to A. McQuatters-Gollop et al. Nature 472, 10.1038/nature09950 (2011); D. L. Mackas Nature 472, 10.1038/nature09951 (2011); R. R. Rykaczewski & J. P. Dunne Nature 472, 10.1038/nature09952 (2011)

In their thoughtful responses to our article on global chlorophyll (Chl) trends1, Mackas2, Rykaczewski and Dunne3, and McQuatters et al.7 suggest that some of the variation observed in our analysis may be explained by a possible bias, whereby transparency-derived chlorophyll (CT) measurements overestimate phytoplankton abundance relative to direct in situ chlorophyll (CI) measurements. Although we cannot entirely discount the possibility that changes in sampling methods may introduce fractional bias, extensive sensitivity analyses detailed below show that this is not responsible for the observed Chl declines. Furthermore, the accuracy of CT as a proxy of surface Chl has been independently verified4,5, and indicates that CT explains only 0.5–1.5% less of the variance in surface Chl than precision measurements of water-leaving radiance (remotely sensed ocean colour)5.

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Correspondence to Daniel G. Boyce.

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Boyce, D., Lewis, M. & Worm, B. Boyce et al. reply. Nature 472, E8–E9 (2011). https://doi.org/10.1038/nature09953

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