Modeling spiny lobster larval dispersion in the Tropical Atlantic

Spiny lobsters have a relatively long larval phase with a planktonic duration of about 1 year. Phyllosomas lack efficient swimming ability and large-scale oceanic geostrophic currents are responsible for long-distance transport of larvae away from the spawning area. This raises the possibility that adult stocks might be connected across large distances by larvae transport. We investigated larval dispersion across the Tropical Atlantic (20°N–15°S; 15°E–45°W) using a simple advection–diffusion model. The model updates the position of each virtual larva every day, over 365 days using the surface geostrophic velocity fields derived from satellite altimetry. The diffusive part of the model was calculated from drifting buoy velocities. We calculated the mean zonal and meridional diffusivity (kx = 3.97 × 107 cm2/s and ky = 2.05 × 107 cm2/s) to incorporate into the model. The velocities obtained from the altimeter data were correlated with drifting buoy velocities resulting in a good agreement for both zonal (r = 0.94, p = 0.05) and meridional (r = 0.65, p = 0.05) components. This suggests that satellite-derived geostrophic flow is a good estimation for the real mean surface velocity field in the study region. Simulations indicate that Brazilian continental shelf adult stocks are connected to larvae released from oceanic islands, such as São Pedro and São Paulo Archipelago, Atol das Rocas and Fernando de Noronha Archipelago. Simulations also indicate that virtual larvae from the Ivory Coast are retained in the eastern side of the basin, whereas Cape Verde Archipelago virtual larvae do not spread far from the spawning area because of the local mesoscale eddy activity.