Resistance of rocky intertidal communities to oceanic climate fluctuations

since SSWD (R2 = 0.040, 0.029, & 0.006, respectively; Fig 11c–11e; Table 5b;). Low zone diver- sity increased with calmer NPGO conditions, increased upwelling, and warmer sea surface temperatures (R2 = 0.030, 0.001, & 0.065, respectively; Fig 11f–11h; Table 5c). The strongest trend was increased diversity with years since SSWD in the low zone (R2 = 0.229; Fig 11i, Table 5c). Discussion Marked resistance of intertidal communities to oceanic variation Our most striking finding was the consistency in rocky intertidal communities along the Ore- gon and Northern California coasts over the 14 years of study. We found little to no support for strong oceanic climate-driven fluctuations in community structure (Figs 7–9, Table 2), and only modest correlations between taxon abundance and climate fluctuations (Table 3). Analy- ses of rates of community change and change in diversity yielded similar results (Tables 3 and 4), suggesting that communities within the Oregon and northern California intertidal meta- ecosystem were resistance to environmental variation, at least during the 14 years of our study for the particular community parameters measured. Since several key ecological processes (e.g. growth, recruitment, resilience) have declined or become more variable with to climate change [11,12], this apparent resistance came as a surprise. We expected intertidal communities to be sensitive to oceanic climate for several reasons. First, several studies have found evidence of range shifts or shifting dominance of northern/

southern species in the intertidal over the past decades [67,68,98], and rocky intertidal Table 3. (Continued) c) Low zone Model Response Average Annual Dissimilarity Model Marginal R2 Sig. Terms (p < 0.0065) Bivariate Correlation Limpets 2.93 0.52 Mean PDO -0.088 Mean NPGO 0.059 Mean ENSO -0.097 BEUTI 0.001 SD BEUTI -0.004 Max Air Temp -0.003 Mean SST -0.123 Yr Since SSWD -0.050 Surf grass 2.61 0.09 Mean PDO 0.009 Mean NPGO 0.007 SD BEUTI -0.111 Hedophyllum sessilis 2.51 0.06 Mean SST -0.030 Crustose Coralline Algae 2.12 0.20 None sig. Cryptopleura and Hymenena 2.08 0.11 None sig. Odonthalia and Neorhodomela 1.94 0.05 None sig. Bare Space 1.77 0.08 Mean NPGO 0.009 Mean ENSO -0.018 Max Air Temp 0.029 Mean SST -0.085 Yr Since SSWD -0.047 Articulated Coralline Algae 1.73 0.07 BEUTI -0.027 Max Air Temp <0.001 https://doi.org/10.1371/journal.pone.0297697.t003 PLOS ONE Resistance of rocky intertidal communities PLOS ONE | https://doi.org/10.1371/journal.pone.0297697 May 29, 2024 19 / 34