Table 1.
Information on National Marine Sanctuaries located off the coast of the California Current System, north to south [29–33].
Fig 1.
National Marine Sanctuaries within the California Current System.
Basemap was sourced from Natural Earth via the rnaturalearth() package in R.
Fig 2.
Examples of marine cold-spell detection methods.
A displays 120 years of modeled sea surface temperature (dynamically downscaled from the Geophysical Fluid Dynamics Laboratory ESM2M) and detrended time series (calculated by subtracting predictions from daily, quadratic regressions of SST) for a grid cell in Monterey Bay. B displays marine cold-spell detection from the ensemble sea surface temperature and the anomaly during a four year period. Sea surface temperatures and anomalies that fall below their respective thresholds (represented by light blue lines) for more than five days are defined as marine cold-spell events.
Fig 3.
Projected change in marine cold-spells in the California Current System from the historical period (1980-2009) to the future period (2070-2099).
A and B display ensemble mean projections of the average number of fixed baseline marine cold-spell days per year across the three climate models. C and D show projections of the average number of detrended marine cold-spell days per year across the three climate models.
Fig 4.
Projected changes in marine cold-spells within California’s National Marine Sanctuaries.
A, C, and E show changes in fixed baseline marine cold-spells. B, D, and F show changes in detrended marine cold-spells. All plots show decade on the x-axis and National Marine Sanctuary name (ordered North to South) on the y-axis. A and B are colored by the mean number of cold-spells per year. C and D are colored by the mean cold-spell duration in days. E and F are colored by the average difference between typical sea surface temperatures and sea surface temperatures during marine cold-spell events. All metrics are calculated for each model individually and then three models are averaged. All metrics for the Channel Islands in the 2090s are zero for fixed baseline marine cold-spells because no fixed baseline marine cold-spells were detected in this sanctuary during this time.
Fig 5.
Projected change in blue whale and leatherback sea turtle core habitat in the California Current System from the historical (1980-2009) to the future (2070-2099).
A, B, D, and E display average predicted habitat suitability values (across ESMs) for these species from July to October, when these species migrate to the California Current. Habitat suitability values of one (yellow) indicate a high likelihood of species presence while values of zero (dark blue) indicate very low chances of species presence. Core habitat for each species is outlined in white. C and F display the differences between historical and future habitat suitability values (future minus historical period) with National Marine Sanctuaries outlined in black where blue represents gain of core habitat and red represents loss of core habitat.
Table 2.
Mean changes in blue whale and leatherback core habitat in National Marine Sanctuaries during marine cold-spells from the historical and future periods. The historical period is defined as 1980-2009 and the future period is defined as 2070-2099. Habitat changes are averaged across five National Marine Sanctuaries and three downscaled ESMs.
Fig 6.
Projected change in core habitat for blue whales and leatherbacks during July-October marine cold-spells in National Marine Sanctuaries.
For each plot, columns represent twelve decades of data and rows represent each of the five National Marine Sanctuaries in latitudinal order. The color fill in each cell represents the relative percentage change of core habitat available to the study species during marine cold-spells relative to typical conditions (calculated as the change in core habitat available divided by the size of the National Marine Sanctuary). For fixed baseline marine cold-spells, typical conditions are defined as the period between 1980 and 2009. For detrended marine cold-spells, typical conditions are defined as a three-decade sliding window of contemporaneous conditions (except for marine cold-spells occurring in 2080 and 2090, when typical conditions are defined by a two-decade window). A and C display changes in blue whale core habitat while B and D display changes in leatherback core habitat. A and B show the species’ responses to fixed baseline marine cold-spells and C and D show responses to detrended marine cold-spells.
Fig 7.
Blue whale and leatherback sea turtle modeled response curves to sea surface temperature modeled across two different periods for the Monterey Bay National Marine Sanctuary.
A displays blue whale summer/fall model response curve (black line with 95% confidence interval in gray) and B displays the leatherback turtle response curve. Horizontal straight lines in the leatherback turtle model response curve represent an extrapolation from the model response at the lowest or highest observed sea surface temperatures. The density plot on A displays sea surface temperatures used to calculate habitat response to marine cold-spells between 2020-2029 in Monterey Bay; the density plot on B displays sea surface temperatures used to calculate responses between 2080-2089. Red density curves are sea surface temperature modeled during a thirty-year window surrounding the decade of interest and blue density curves are sea surface temperatures occurring during modeled, detrended marine cold-spells during the decade of interest. Vertical lines represent mean typical (red) and marine cold-spell (blue) temperatures. Sea surface temperatures are derived from an ensemble of the downscaled projection forced by the IPSL, GFDL, and HAD CMA5A-MR RCP models under the RCP 8.5 scenario.