Abstract


Water dynamics around Cocos Island, Costa Rica. Surface and sub-surface data were analyzed using chemical and physical parameters, nutrients and dissolved oxygen in the eastern tropical Pacific, based on databases, numerical models and satellite observations. The surface marine current pattern during the first quarter of the year was different from the rest. It is known that the North Equatorial Countercurrent does not reach the island at this time, and a clockwise gyre centered on Isla del Coco (Cocos Island) was stabilized with an intense coastal current generated south of the Gulf of Panama, initially moving in a south direction and then west. It is at this time when the Inter-tropical Convergence Zone is at its most northerly position (around 10°N), and the dynamics of the eastern tropical Pacific is driven by the surface Caribbean easterly wind stress crossing the topographic gaps in Central America. The upwelling in the Gulf of Papagayo is evident and from the surface spatial distributions of temperature, salinity and nutrients, an advection towards Isla del Coco is identified. When the Inter-tropical Convergence Zone is displaced to the south (around 5°N), the Papagayo upwelling disappears, the southern trade winds intensify and a strong Equator-Peru upwelling is developed. Nevertheless, from the latitudinal depth profiles and the spatial distributions of physical parameters and nutrients, no advection is evident in the monthly averages from this zone. Between May and October the island was always reached by the North Equatorial Countercurrent. On average, the waves that reach Isla del Coco arrive from the southwest. However, during the boreal winter, the storms generate waves with sufficient energy to reach the island from the northwest. Additionally, at this time of the year, Trade Winds from the Caribbean blow strong across the topographical Papagayo and Panama gaps, generating waves towards the southwest that can reach the island and the remote swell from the southwest losses energy. Rev. Biol. Trop. 56 (Suppl. 2): 31-48. Epub 2008 August 29.
Keywords: Cocos Island, eastern tropical Pacific, nutrients, surface currents, latitudinal profiles, Isla del Coco, Costa Rica