Resistance of rocky intertidal communities to oceanic climate fluctuations

space at Cape Perpetua (17.0% and 6.3% contribution, respectively) and gooseneck barnacles at Cape Foulweather (5.9% contribution). In the low zone, most capes differed from one another (Fig 5c; S3c Table in S1 Appendix) except Cape Blanco did not differ from Capes Foul- weather or Mendocino (p = 0.091 and 0.089 respectively). Sites again differed within capes (p < 0.032 for site comparisons). Like the other zones, in the low zone many of the same taxa dominated every cape, but their relative contributions to cape separation differed (Fig 5c; S3f Table in S1 Appendix). For example, Cape Foulweather was associated with relatively low bare space but with high coralline algae crusts, Hedophyllum sessile, and Cryptopleura ruprechtiana/ Hymenena flabelligera (Fig 5c; S3f Table in S1 Appendix, 11.4%, 10.9%, 7.7%, and 6.1% contri- bution, respectively) while Cape Perpetua had relatively more sea anemones, predatory sea stars, and gooseneck barnacles (10.0%, 5.1% and 5.0% contribution, respectively). Community structure over time Interannual differences occurred in all zones, with year accounting for 19.9%, 19.4%, and 14.7% of the community variation in high, mid and low zones, respectively (S3a-S3c Table in S1 Appendix; Year: p = 0.001 for each zone, see % calculation in methods). However, these Fig 4. Non-metric multidimensional scaling (nMDS) plots depicting Bray-Curtis dissimilarity in community structure among high (yellow), mid (green), and low (blue), and intertidal zones. Vector overlays depict species contributing >3% to within-zone similarity in SIMPER analyses (S2b

Table in S1 Appendix). Each data point represents a community at the transect level (the average of ~ten 0.5 x 0.5m quadrats). https://doi.org/10.1371/journal.pone.0297697.g004 PLOS ONE Resistance of rocky intertidal communities PLOS ONE | https://doi.org/10.1371/journal.pone.0297697 May 29, 2024 12 / 34