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 (∼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.

The choice of droplet size probability distribution function for oil spill modeling is not trivial.

The droplet size distribution (DSD) formed by gas-saturated oil jets is one of the most important characteristics of the flow to understand and model the fate of uncontrolled deep-sea oil spills. The shape of the DSD, generally modeled as a theoretical lognormal, Rosin-Rammler or non-fundamental distribution function, defines the size and the mass volume range of the droplets. Yet, the fundamental DSD shape has received much less attention than the volume median size (d50) and range of the DSD during ten years of research following the Deepwater Horizon (DWH) blowout. To better understand the importance of the distribution function of the droplet size we compare the oil rising time, surface oil mass, and sedimented and beached masses for different DSDs derived from the DWH literature in idealized and applied conditions, while keeping d50 constant. We highlight substantial differences, showing that the probability distribution function of the DSD for far-field modeling is, regardless of the d50, consequential for oil spill response.