Community structure and recovery in cryptic intertidal communities reflects dynamics on open-surface communities

Research on intertidal community structure and recovery in the California Current System has largely focused on macrophytes and invertebrates occupying two-dimensional, readily studied open rock surfaces. However, most rocky shores have a third dimension that includes channels, cracks, crevices, and overhangs whose organismal assemblages, termed cryptic communities, are poorly studied. Cryptic communities not only share many species with those on more accessible surfaces but also include high abundances of colonial invertebrates such as tunicates, sponges, bryozoans, and hydrozoans. We investigated species abundance and diversity of cryptic communities and tested their recovery from disturbance by comparing removal plots to undisturbed controls for similar to 1.5 years. Additionally, we tested whether community structure and recovery varied with contrasting large-scale levels of ecological subsidies (invertebrate recruitment, nutrients, and phytoplankton) and local-scale microhabitat differences (emersion and solar irradiation) on the Oregon Coast. We compared cryptic recovery rates to recovery rates on open-surface communities. In cryptic communities, site explained most (92%) variance in community structure of undisturbed plots, while microhabitat metrics had little (1.2%) effect. Further, recovery rates were faster at a site with higher subsidy inputs than one with lower subsidies in both cryptic and noncryptic communities. Hence, larger scale environmental drivers appeared more important than local-scale drivers within cryptic communities. Our research provides novel insight into intertidal cryptic surge channel community structure and dynamics.

Automated summary

Research on the intertidal community structure and recovery in the California Current System has focused mainly on easily accessible macrophytes and invertebrates on open rock surfaces. However, the cryptic communities in the three-dimensional structures on rocky shores have been poorly studied. In this research, we investigated the species abundance and diversity of the cryptic communities and their recovery from disturbance over a period of approximately 1.5 years. Our findings suggest that larger-scale environmental drivers are more influential than local-scale drivers in determining the community structure and recovery rates of the cryptic communities.