Resistance of rocky intertidal communities to oceanic climate fluctuations

Taxon diversity Taxon diversity (H’) varied among sites, years, and their interaction in all three zones but most changes were small, accounting for little variance (S7 Fig in S3 Appendix; S4 Table in S1 Appendix). For example high zone diversity increased slightly with warmer PDO and cooler maximum air temperatures (R2 = 0.042 and 0.029, respectively; Fig 11a&11b; Table 5a). Mid zone diversity increased with windier NPGO and La Niña conditions and decreased with years Fig 7. Bivariate regressions between the percent cover of focal functional groups (significant functional groups in Table 2a with the 8 focal climate variables in the high zone. Each data point is the average abundance of a functional group for a site and year. Environmental drivers included Pacific Decadal Oscillation index (mean PDO), North Pacific Gyre Oscillation index (mean NPGO), Multivariate El Niño Southern Oscillation Index (mean ENSO), Biologically Effective Upwelling Transport Index (mean BEUTI), the standard deviation in BEUTI (SD BEUTI), the maximum daily air temperature in celcius by site (Max Air Temp), the mean daily water temperature in celcius by site (Mean SST) and the years since the initial sea star wasting disease outbreak (Yrs since SSWD). Colors correspond to functional groups, with fucoid algae in green, mussels (Mytilus spp.) in in blue, herbivorous snails in pink, and limpets in purple. Units for fucoid algae and mussels are in percent cover while limpets and herbivorous snails are in density m-2. Some high

densities (100-400m-2) of limpets are not shown in plots to enable visualizations of fits. https://doi.org/10.1371/journal.pone.0297697.g007 PLOS ONE Resistance of rocky intertidal communities PLOS ONE | https://doi.org/10.1371/journal.pone.0297697 May 29, 2024 17 / 34