Resistance of rocky intertidal communities to oceanic climate fluctuations

subtle changes that we were able to detect in our study, and contemplate whether we can expect this resistance to continue in the future. The disconnect between varying ecological processes and emergent community structure Our analysis suggests that as of 2020, the general structure of rocky intertidal communities on our shore appeared resistant to climate change. What is the underlying basis for the resistance of these communities to oceanic climate variation? We explore two ecological and possibilities: Table 4. Results of multiple regression analyses and bivariate regressions testing drivers of rate of community change in a) high, b) mid, and c) low intertidal zones in Oregon and northern California from 2006–2021. We tested the effects of peak seasonal climate indices for mean Pacific Decadal Oscillation index (mean PDO), mean North Pacific Gyre Oscillation index (mean NPGO), mean El Niño Southern Oscillation index (mean ENSO), mean and stan- dard deviation of the Biologically Effective Upwelling Transport Index index (mean and sd BEUTI, respectively), mean daily sea surface temperature (Mean SST), mean daily maximum air temperature (Max Air Temp), and years since the sea star wasting disease epidemic (Yr Since SSWD). Communities were analyzed at the quadrat level in the mid and high zones (0.5 x 0.5m) and the transect level in the low zone (the average of ~10 0.5 x 0.5m quadrats). Bold statistics indicate significant terms (Bonferroni cutoff P < 0.002). Factor Chisq Df Pr(>Chisq) Bivariate Adj R2 a) High Zone Intercept 0.76 1 0.3820 Mean PDO 0.12 1 0.7339

Mean NPGO 2.30 1 0.1298 Mean ENSO 1.92 1 0.1653 Mean BEUTI 2.25 1 0.1334 SD BEUTI 3.33 1 0.0681 Mean SST 0.14 1 0.7069 Max Air Temp 0.91 1 0.3398 Yr Since SSWD 3.33 1 0.0679 b) Mid Zone Intercept 5.55 1 0.0185 Mean PDO 0.03 1 0.8556 Mean NPGO 8.34 1 0.0039 Mean ENSO 9.71 1 0.0018 -0.003 Mean BEUTI 0.85 1 0.3557 SD BEUTI 0.53 1 0.4681 Mean SST 0.19 1 0.6612 Max Air Temp 6.05 1 0.0139 Yr Since SSWD 9.51 1 0.0020 -0.019 c) Low Zone Intercept 9.21 1 0.0024 Mean PDO 4.46 1 0.0347 Mean NPGO 1.77 1 0.1836 Mean ENSO 0.55 1 0.4587 Mean BEUTI 0.10 1 0.7575 SD BEUTI 1.62 1 0.2037 Mean SST 0.28 1 0.5953 Max Air Temp 13.39 1 0.0003 0.069 Yr Since SSWD 2.74 1 0.0980 https://doi.org/10.1371/journal.pone.0297697.t004 PLOS ONE Resistance of rocky intertidal communities PLOS ONE | https://doi.org/10.1371/journal.pone.0297697 May 29, 2024 22 / 34