How Much Do Marine Connectivity Fluctuations Matter?

There is growing awareness that fluctuations in larval flux (connectivity) depress the long-run growth of marine metapopulations, but by how much is unclear. Here, we explore how reproductive schedule and larval behavior affect how much connectivity fluctuations depress growth. We combine larval dispersal simulations from the Florida Keys with theoretical results to calculate the effect of fluctuations on bicolor damselfish (Stegastes partitus). We find that fluctuations depress growth only slightly (similar to 2%), but the effect would be much stronger for an organism that spawned only part of the year. Larval behavior can also matter, as vertical migration allows larvae to become entrained in eddies. Eddies synchronize connectivity fluctuations, further decreasing growth. However, here, they also divide the Keys into largely independently fluctuating regions, mitigating the effects of local synchrony. Therefore, in situations where connectivity fluctuations matter, the presence of independently fluctuating regions due to larval behavior may be important.