Restoration of native oyster populations relies on an understanding of inter-population connectivity and metapopulation dynamics. This study modelled the effects of connectivity on recruitment and metapopulation dynamics of the eastern oyster Crassostrea virginica for a planned restoration by the US Army Corps of Engineers in the Tangier Sound-Pocomoke Sound (TSPS) system, an area of about 70,000 ha encompassing 56 potential restoration sites in lower Chesapeake Bay. Modeling integrated (i) historical and recent data on habitat suitability, (ii) analysis of multiple connectivity matrices representing diverse environmental conditions, and (iii) a stage-structured metapopulation model linking individual population models for each of the populations through the connectivity matrices. Biophysical modeling involved release of virtual larvae from multiple potential reef patches in the metapopulation, advection for 2 weeks, larval mortality, and settlement on reef patches for 1 week.
Connectivity patterns were diverse and varied significantly among the metapopulations, but could be classified according to the construct of source-sink dynamics. Populations were characterized by their value to restoration, ‘bet-hedging’ strategies, resilience to climate change, and as linked harvest grounds subsidized by protected source populations. Populations in a metapopulation could be sources, sinks, pseudo-sinks and stepping stones, among others. Modeling indicated that the TSPS system was comprised of three loosely connected metapopulations, which made it difficult to optimize connectivity of simulated restored populations and metapopulation recruitment concurrently. Consequently, a tradeoff exists between restoration of populations across the whole of the TSPS system and maximizing metapopulation recruitment.