Strategies for keeping marine ecosystems connected tend to focus on one of two paradigms. One is to maintain connectivity through support of larval dispersal, which leads to the conservation strategy of stratifying marine reserves to maintain larval connectivity. The other looks to maintain connectivity through support of juvenile migration from nurseries to adult habitats, which leads to connecting corridors of adjacent habitats to support ontogenetic migration routes. Both life stages – larvae and juvenile – contribute to adult fish abundance, so finding a common driver that unifies larval dispersal to juvenile migrations would unify marine connectivity strategies to better conserve many fish species.
New research by Brown et al. suggests a connecting factor between the two paradigms: wave and wind exposure, i.e. how sheltered a nursery and reef are. Using the examples of tropical coral reef fish in The Bahamas, they combined habitat maps with empirically forced models of wave exposure and larval dispersal to make predictions about adult population response. They model movement across a larger scale than would be possible using only empirical data, allowing for a more thorough look at how movement may happen.
Their results suggest a synergy between elevated larval retention and the presence of lagoonal nurseries that benefit the fish species on adjacent reefs. Sheltered conditions are likely to lead to higher adult abundances, particularly in seascapes like The Bahamas where low exposure to wind and waves coincide with suitable conditions for mangroves and seagrass that act as nursery sites.
Linking these two paradigms of larval and juvenile movement could lead to simplified conservation advice for fisheries management. Reserves that are located in sheltered environments may provide multiple opportunities to protect biodiversity, while at the same time benefiting local fisheries through adult spillover. This merging of management and conservation goals makes it much more possible to achieve connectivity goals that benefit multiple species.
Brown, C. J., A. R. Harborne, C. B. Paris, and P. J. Mumby. 2016. Uniting paradigms of connectivity in marine ecology. Ecology 97(9): 2447-2457.