The Effects of Wave Exposure and Tidal Height on Rocky Intertidal Community Dynamics

Rocky intertidal ecosystems are impacted by many different abiotic and biotic factors. Specifically, both wave exposure and tidal height have been shown to have strong effects on the dynamics of intertidal communities. Wave exposure and tidal height have long been shown to limit the ranges and abundance of intertidal organisms, although the relative importance of the two factors and the relationship between them has not been thoroughly examined. In this study, we set up vertical transects at two sites, one wave-exposed and one wave-protected, at the Hopkins Marine Station in the Monterey Bay National Marine Sanctuary. We found that the two sites contained similar levels of species abundance and richness except among mobile invertebrate populations. There was significantly higher mobile invertebrate abundance and species richness in the protected site compared to the waveexposed site. However, we found no significant difference in mobile invertebrate species richness or abundance corresponding to variations in tidal height. As a result, we conclude that wave exposure is relatively more important than tidal height in contributing to mobile invertebrate abundance and species richness. Better understanding of community dynamics is essential to efficiently allocate resources to conservation efforts as we strive to protect our natural world.