Project: Scaling up from community to meta-ecosystem dynamics in the rocky intertidal - a comparative-experimental approach

Collaborative Research: Scaling up from community to meta-ecosystem dynamics in the rocky intertidal - a comparative-experimental approach

The meta-ecosystem concept hypothesizes that the dynamics of ecological communities reflect interdependence between local-scale and ecosystem processes that vary across large distances. Thus, variation among communities depends not only on locally-varying species interactions and abiotic factors, such as physical disturbance, but also on regionally- and globally-varying ecosystem processes, such as dispersal and flows of materials such as nutrients and carbon. This study of rocky intertidal communities and the factors underlying their variation addresses the issue of meta-ecosystem dynamics. The goal of this project is to understand how variability in oceanographic subsidies, such as nutrients and phytoplankton, influences benthic community structure in the northern California Current Large Marine Ecosystem. Local-scale variation in upwelling along the Oregon and northern California coasts will be used to understand how changes in nutrients and productivity influence benthic-pelagic coupling, its effect on benthic species interactions, and ultimately rocky intertidal community structure. A conceptual model, in which the independent variable is seawater temperature (SWT), is used to predict how the dual effect of nutrients and light on marine benthic and pelagic primary production generates different community outcomes in the low intertidal zone. The two "endpoints" of community structure are a dominance of filter feeding invertebrates or macroalgae. The model predicts that with low (cold) SWT, nutrient and light availability is high, and macrophytes are dominant. Under very high nutrients and light, competitively dominant kelps will prevail and possibly facilitate stress-intolerant macroalgal species, and as nutrients and light diminish, kelp dominance should switch to dominance by surfgrass and foliose understory algae. With higher (warmer) SWT, conditions favor high phytoplankton production, leading to dominance by sessile invertebrates. High phytoplankton also creates low light and low nutrient conditions, negatively affecting growth of macroalgae and their ability to compete with sessile invertebrates. Research will be conducted at 15 sites nested within five capes spanning the 1300 km range of the study region. A water sampling program will quantify concentrations of nutrients and phytoplankton, field-deployed remote sensors will provide time-series estimates of light and chlorophyll a, and surveys will quantify community structure. Manipulative field experiments will test the role of species interactions on community structure and how interactions vary with ecological subsidies.