Eddies can enhance primary as well as secondary production, creating a diverse meso- and submesoscale
seascape at the eddy front which can affect the aggregation of plankton and particles.
Due to the coarse resolution provided by sampling with plankton nets, our knowledge of plankton
distributions at these edges is limited. We used a towed, undulating underwater imaging system to
investigate the physical and biological drivers of zoo- and ichthyoplankton aggregations at the edge of
a decaying mesoscale eddy (ME) in the Straits of Florida. Using a sparse Convolutional Neural Network
we identified 132 million images of plankton. Larval fish and Oithona spp. copepod concentrations were
significantly higher in the eddy water mass, compared to the Florida Current water mass, only four
days before the ME’s dissipation. Larval fish and Oithona distributions were tightly coupled, indicating
potential predator-prey interactions. Larval fishes are known predators of Oithona, however, Random
Forests models showed that Oithona spp. and larval fish concentrations were primarily driven by
variables signifying the physical footprint of the ME, such as current speed and direction. These results
suggest that eddy-related advection leads to largely passive overlap between predator and prey, a
positive, energy-efficient outcome for predators at the expense of prey.
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