Oceanographic and life history interactions drive spatio-temporal variability of coastal metapopulation connectivity

Background/Question/Methods

Assessing the degree of connectivity among reef sites in a metapopulation is central to understanding persistence of species that inhabit patchy ecosystems and is a fundamental requirement for the effective design of marine protected areas. The interactions between ocean circulation and life history characteristics play a critical role in marine metapopulation dynamics. Here we examine this biophysical interplay in a seemingly well-mixed coastal system using a coupled hydrodynamic and individual-based Lagrangian tracking model to assess larval dispersal across coral reef habitats in Kimbe Bay, Papua New Guinea.

Results/Conclusions

Temporal and spatial variability of oceanographic transport can generate directional and episodic patterns of connectivity even in systems that appear oceanographically well mixed by eddies. Reef sites situated along the coastline may receive fewer potential settlers than more centrally located island sites. Sites near the edges of bay where much bay outflow eventually traverses may also capture settlers from numerous regional sources.  This general pattern can fluctuate considerably within the timescale of dispersal.

Along with oceanographic transport processes, larval survival and settlement competency are also critical for the connectivity of organisms with a bipartite life cycle. Specifically, the inclusion of daily mortality results in higher self-recruitment consistent with previously observed patterns for the region. Other life history characteristics such as pelagic larval duration, minimum competency age and larval settlement behavior also affect successful settlement.