Defining Boundaries for Ecosystem-Based Management: A Multispecies Case Study of Marine Connectivity Across the Hawaiian Archipelago

Determining the geographic scale at which to apply ecosystem-based management (EBM) has proven to be an obstacle for many marine conservation programs.  Generalizations based on geographic proximity, taxonomy or life history characteristics provide little predictive power in determining overall patterns of connectivity, and therefore offer little in terms of delineating boundaries for marine spatial management areas.  Here, we provide a case study of roughly 50 taxonomically and ecologically diverse species (including reef fishes, marine mammals, gastropods, echinoderms, cnidarians, crustaceans and an elasmobranch) that reveal five concordant barriers to dispersal within the Hawaiian Archipelago which are not detected consistently in single-species exemplar studies.  We discuss various approaches to combining multispecies population genetic data and contend that this multispecies approach to determine concordant patterns of connectivity is an objective and logical way in which to define the minimum number of marine spatial management units.  Using this approach, we show that EBM in the Hawaiian Archipelago requires at least six spatially managed regions that do not correspond to predictions from Eulerian advection–diffusion or Lagrangian particle-tracking models of larval dispersal.