Consequences of the life history traits of pelagic larvae on interisland connectivity during a changing climate

Many coral reef organisms possess a pelagic larval phase during which some larvae are retained near spawning sites and others are dispersed to more distant locations via ocean currents. Planktonic duration, distances traveled, and recruitment success can vary due to natural development rate, mortality rate, and sensory and swimming capabilities of particular taxa. Elevated water temperatures and acidification due to climate change can also influence recruitment by generally accelerating metabolism and growth, raising mortality rate, impairing development of calcified structures, and reducing sensory capabilities. We used hydrodynamic models and drifter data to investigate these various life history and climate-related influences on larval connectivity in and around the Samoan Archipelago. In general, virtual larvae spawned in the Samoan Archipelago seeded their natal reefs with relatively short-lived larvae, and their island neighbors to the west with longer-lived larvae. Larval duration, mortality rate, and sensory zone variables all had a significant effect on connectivity. Effect size was largest for mortality rate followed by larval duration. Shortened larval longevity due to climate change reduced interisland connectivity and changed the life history traits (and therefore taxa) that result in successful connections. Islands will generally become increasingly more reliant on self-seeding as the ocean warms, although the role of most islands primarily as a source or destination was robust to climate change.