The intertidal zone, which lies between the high and low tide marks on the shores of the world’s oceans, is a sensitive indicator of the effects of climate variability and climate change on marine species. We examined the effects of long-term temperature changes on the population biology of dominant species in intertidal areas and forecast the impact of climate change on the suitability of estuaries and rocky intertidal shores as nursery grounds for important marine species.

Why We Care
Animals and plants that live in the intertidal zone must contend with the ocean environment at high tide and the terrestrial environment at low tide. As a result, their body temperatures may fluctuate as much as 10° to 20°C over the course of a single low tide. For sedimentary (sand or mud) shores, the target organisms are animals that can either disrupt sediments (e.g., shrimp and worms) or build tubes and reefs (e.g., worms, oysters). For rocky shores, the target organisms are those that occupy and create hard surfaces, such as barnacles and mussels. We forecasted the impact of climate change on the suitability of estuaries and rocky intertidal shores as nursery grounds for commercially and recreationally important marine species.

What We Did
We used biophysical computer models to predict body temperatures of species that provide the ecological foundation in the zone between the tides on the shores of the world’s oceans. We studied barnacles and mussels on rocky shores. Barnacles and mussels control the distribution and abundance of other species in the intertidal zone, because they are able to overgrow their competitors for primary space on the rock. Understanding the influence of climate on these species will allow us to predict the changes in biodiversity and biogeography of marine organisms in response to climate change and variability.

The geographic range of our work was from Alaska to Mexico on the Pacific Coast and Maine to South Carolina on the Atlantic Coast, spanning the geographic limits of these species. NOAA National Estuarine Research Reserves (NERRs) on each coast were included as sample sites and represented different biogeographic provinces.

The project, funded originally and later in part by the NCCOS Ecological Forecasting Program, was led by Dr. David Wethey (University of South Carolina Department of Biological Sciences).

Management Connections
We made important contributions to coastal resource management by developing forecasting tools for coastal managers and planners, especially with the NOAA NERRs. On the West Coast, NERRs sites included Kachemak Bay (AK), Padilla Bay (WA), South Slough (OR), Elkhorn Slough (CA), and Tijuana River (CA). On the East Coast, NERRS sites included Wells Bay (ME), Waquoit Bay (MA), Chesapeake Bay (VA), North Carolina Bays, and North Inlet (SC). Foundation species from each of these regions were identified, and comparisons among species can be made across NERRS sites. We also provide training for NERRs directors and coastal resource managers in the use of the coastal forecasting tools developed.

Benefits of Our Work
In New Zealand, our models were used to explain mass die-offs of sea urchins, which occurred during a period of anomalously high temperature. The project leaders addressed the national NERRS research managers meeting in October 2007, to present the initial results of their work and receive feedback on their model products. We helped the National Weather Service (NWS) develop a new “vegetation type” for their temperature prediction models that includes mussel beds. Also, associated NASA remote sensing funding shows the importance of our work for predicting the climate change impacts to coastal intertidal organisms.