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. 2021 Mar 8;118(11):e2012493118. doi: 10.1073/pnas.2012493118

Fig. 1.

Fig. 1.

Temporal dynamics of sea otters, kelp, sea urchins, and Pycnopodia. (Left) Annual changes in sea otter abundance in the Monterey study region (A) and relative density of kelp stipes (B), exposed sea urchins (C), and Pycnopodia (D). The trend line in A is corrected for observer error and fit with a Bayesian state-space model (SI Appendix, Supplementary Methods) to the time series of raw survey counts of independent sea otters. B–D represent annual mean observed densities fit with a cubic spline (λ = 0.05). Each shaded region across A–D represents the 95% credible interval. (Right) A conceptual illustration of the dynamics that initiated the formation of the mosaic of remnant kelp forests interspersed with sea urchin barrens. See SI Appendix, Supplementary Methods for expanded time series analyses. We used published data for A from the US Geological Survey (available at https://doi.org/10.3133/ds1097) and subtidal data for B–D from the Partnership for Interdisciplinary Studies of Coastal Oceans subtidal surveys (available at https://doi.org/10.6085/AA/PISCO_SUBTIDAL.151.2).