Special Session - Marine and Coastal Applications in Landscape Ecology - Morning Session Chair(s): Nicholson, Matt¹, Hinchey, Elizabeth¹, Robbins, Brad², ¹ Atlantic Ecology Division, Narragansett, RI² Landscape Ecology Division, Sarasota, FL
Friday, April 2, 2004 9:00 AM - 11:00 AM Zeus Room B

Although applications in landscape ecology traditionally have been restricted to the study of terrestrial systems, the questions defining the science are equally relevant for marine systems. Indeed, knowledge of spatial pattern and the scales at which ecological processes take place is essential for effective management of marine environments. However, scattered and widely disparate field or ship-based observations historically precluded quantification of large-scale marine patterns. Recent advances in remote sensing and other technologies are permitting assessments of pattern and process that never before were possible. It is still unclear how the principles of landscape ecology can be translated into the marine environment, a three-dimensional milieu with physical and biological characteristics that often vary rapidly in space and time. This session will bring together researchers who are attempting to adapt the tools of landscape ecology to address ecological questions within marine and coastal systems. The unique challenges facing the growing field of “seascape” ecology will be addressed.

Exploring marine connectivity in the South Pacific with graph theory. Treml, Eric^*,1, Halpin, Patrick¹, ¹ Nicholas School of the Environment and Earth Sciences, Durham, NC, USA

ABSTRACT- The dispersal of individuals to and from marine populations is of great importance to metapopulation dynamics, population persistence, and species expansion. Understanding this connectivity between distant populations, and reserves, is key to their effective conservation and management. For many marine species, this population connectivity is determined, in large part, by ocean currents transporting larvae and juveniles between distant patches of suitable habitat. Recent work has focused on the biophysics of marine larval dispersal and its importance to population dynamics, although few studies have evaluated the spatially and temporally explicit patterns in this potential dispersal. Here, we use ocean current vectors and an advection-diffusion approach to model the potential dispersal between coral reefs of the South Pacific. Our series of dispersal simulations compare seasonal and year-to-year variability in connectedness across this region. This time series of probabilistic dispersal paths between reefs are analyzed using graph theory   an effective approach to exploring patterns in spatial connections, as well as performing site and pathway importance scenarios. Spatial analysis reveals striking differences in both the distance, and the direction, of potential larval dispersal throughout the region. Temporal comparisons between seasons and among years highlight striking variability at these time-scales. Patterns in these directional dispersal graphs illustrate possible pathways for species expansions, identify critical island 'stepping stones', reveal potentially connected upstream/downstream populations, and suggest areas suitable for marine reserve consideration. In addition, these graphs provide a testable model for explaining species and genetic similarities between distant reef systems.

KEY WORDS: graph theory, connectivity, South Pacific, dispersal