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GGAM PhD Exit Seminar: Great Risk, Grave Uncertainty, and Making Your Own Luck: Marine Larval Dispersal in Heterogeneous Environments

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Speaker: Alex Meyer
Start time: Fri, Jun 4 2021, 2:10PM

Abstract: Many coastal marine invertebrates and fish begin life as planktonic larvae. At the mercy of coastal currents, larvae may be transported hundreds of kilometers from their parents’ habitats. However, they must return to coastal habitats to have any hope of surviving until reproduction. Most larvae fail to do so. Therefore, the dynamics of many coastal populations cannot be understood without considering the movement and mortality of their larvae. Larvae are weak swimmers but can improve their chances of successful dispersal by taking advantage of the spatial structure of their environment. By swimming vertically through the water column, larvae exploit depth-driven variations in current velocity, predator abundance, and food density. Although several vertical swimming behaviors have been observed (or inferred) empirically, it is not obvious when and why certain behaviors are more advantageous than others. In this talk, I use stochastic modeling to compare the benefits of different swimming behaviors across several environments. First, I use a “top-down” approach that assumes larval behaviors are selected from a general class based on those seen in nature. Second, I supplement this with a “bottom-up” approach, using dynamic programming to construct optimal behaviors from scratch. My results indicate that some empirically observed behaviors are optimal under specific circumstances, and others perform robustly against variable conditions. More generally, I highlight how environmental heterogeneity creates opportunities for even slow-moving organisms to change their fates through carefully executed behaviors.

Zoom link: Passcode: larva