Well-managed and enforced no-take marine reserves generate important larval subsidies to neighboring habitats and thereby contribute to the long-term sustainability of fisheries. However, larval dispersal patterns are variable, which leads to temporal fluctuations in the contribution of a single reserve to the replenishment of local populations. Identifying management strategies that mitigate the uncertainty in larval supply will help ensure the stability of recruitment dynamics and minimize the volatility in fishery catches. Here, we use genetic parentage analysis to show extreme variability in both the dispersal patterns and recruitment contribution of four individual marine reserves across six discrete recruitment cohorts for coral grouper (Plectropomus maculatus) on the Great Barrier Reef. Together, however, the asynchronous contributions from multiple reserves create temporal stability in recruitment via a connectivity portfolio effect. This dampening effect reduces the variability in larval supply from individual reserves by a factor of 1.8, which effectively halves the uncertainty in the recruitment contribution of individual reserves. Thus, not only does the network of four marine reserves generate valuable larval subsidies to neighboring habitats, the aggregate effect of individual reserves mitigates temporal fluctuations in dispersal patterns and the replenishment of local populations. Our results indicate that small networks of marine reserves yield previously unrecognized stabilizing benefits that ensure a consistent larval supply to replenish exploited fish stocks.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We acknowledge this research took place on the traditional land and sea country of the Woppaburra people and recognize their continuing connection to land, water, and community in the Keppel Islands. We thank our field assistants for support with sample collection, and Lisa Boström Einarsson, Darren Cameron, Graeme Cummings, and Rachel Pears for their thoughtful comments on an earlier version of this manuscript. This work was funded by an Australian Research Council (ARC) Discovery Early Career Research Award to H.B.H. (DE160101141); an ARC Discovery Grant to G.P.J., M.B., and M.L.B. (DP190103056); and an ARC Future Fellowship to M.B. (FT170100274). Additional support was provided by the ARC Centre of Excellence for Coral Reef Studies (Grant CE140100020) and King Abdullah University of Science and Technology baseline research funds.