Use of geostrophic currents derived from radar altimeter to study lobster larvae dispersion in the tropical atlantic / Análise da dispersão de larvas de lagostas no Atlântico tropical a partir de correntes geotróficas superficiais derivadas por satélites

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Three species of spiny lobster are harvested along the Brazilian coast (Panulirus argus, P. laevicauda and P. echinatus). The annual revenue amounts 50 to 60 million US dollars. These species have a relatively long planktonic larval phase (about one year), that enables the mean ocean currents to transport the larvae over long distances away from the original spawning area. This raises the question of how the adult stock can be maintained in regions where the mean flow tends to advect larvae. To answer this question we investigate the larval dispersion across the tropical Atlantic (20°N-15°S; 15°E-45°W) to verify possible connectivities among different stocks. We use an advection-diffusion model that updates the position of each larva everyday, along 365 days using the surface geostrophic velocity fields derived from altimeter satellites. These velocities were correlated with drifting buoys velocities, resulting in a good agreement for both the zonal component (r = 0,94) and the meridional component (r = 0,65). This indicates that the satellite-derived geostrophic flow represents a good approximation of the real velocity field for the region. The coefficient of diffusivity used in the model was calculated from the velocities of drifting buoys and a mean value was estimated to represent the zonal diffusivity (kx = 3970m2/s) and the meridional diffusivity (ky = 2050m2/s). Results of the spawning simulations in the coast of Africa indicate that the larval stock does not spread far from the spawning area, suggesting that the African stocks can not sustain the Brazilian stocks. Simulations also indicate that the Brazilian stocks could be maintained with larvae input from oceanic islands (Fernando de Noronha, São Pedro/São Paulo Archipelagos and Atol das Rocas). It is possible, however, that middle Atlantic Islands, such as Ascension Island, act as stepping-stones between the African and the South-American continents.

ASSUNTO(S)

palinuridae bóias de deriva altimeter satellites estoques pesqueiros fishery stocks satélites altímetros drift buoy atlântico tropical palinuridae sensoriamento remoto tropical atlantic remote sensing

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