The annual cycle and biological effects of the Costa Rica Dome

NOAA/National Marine Fisheries Service (NMFS), Southwest Fisheries Science Center, P.O. Box 271, La Jolla, CA 92038, USA
Deep Sea Research Part I Oceanographic Research Papers (Impact Factor: 2.57). 02/2002; 49(2):321-338. DOI: 10.1016/S0967-0637(01)00057-7


The Costa Rica Dome is similar to other tropical thermocline domes in several respects: it is part of an east–west thermocline ridge associated with the equatorial circulation, surface currents flow cyclonically around it, and its seasonal evolution is affected by large-scale wind patterns. The Costa Rica Dome is unique because it is also forced by a coastal wind jet. Monthly climatological fields of thermocline depth and physical forcing variables (wind stress curl and surface current divergence) were analyzed to examine the structure and seasonal evolution of the dome. The annual cycle of the dome can be explained by wind forcing in four stages: (1) coastal shoaling of the thermocline off the Gulf of Papagayo during February–April, forced by Ekman pumping on the equatorward side of the Papagayo wind jet; (2) separation from the coast during May–June when the intertropical convergence zone (ITCZ) moves north to the countercurrent thermocline ridge, the wind jet stops, and the North Equatorial Countercurrent extends toward the coast on the equatorward flank of the ridge; (3) countercurrent thermocline ridging during July–November, when the dome expands to the west as the countercurrent thermocline ridge shoals beneath a band of cyclonic wind stress curl on the poleward side of the ITCZ; and (4) deepening during December–January when the ITCZ moves south and strong trade winds blow over the dome. Coastal eddies may be involved in the coastal shoaling observed during February–March. A seasonally predictable, strong, and shallow thermocline makes the Costa Rica Dome a distinct biological habitat where phytoplankton and zooplankton biomass are higher than in surrounding tropical waters. The physical structure and biological productivity of the dome affect the distribution and feeding of whales and dolphins, probably through forage availability.

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Available from: Paul C. Fiedler, Oct 09, 2015
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    • "The marine area represents 0.16% of the world's ocean surface but harbors 3.5% of the known marine biodiversity [42] [43]. The Costa Rican Dome (8–10°N, 88–90°W) is an area with high primary production that supports a high zooplankton biomass [44] [45] contributing to the high biodiversity. "
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    • "Concentrations of ammonia and nitrate at the study site significantly increased during upwelling season between February and April compared to non-upwelling season. This corresponds with findings of climatological studies of Wyrtki (1964) and Fiedler (2002), who analyzed the structure and seasonal evolution of the Costa Rica upwelling dome. Along with inorganic nutrient concentrations, the chlorophyll a concentration doubled within the given time frame, indicating high phytoplankton activity. "
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    • "A prominent feature of the oceanography in the Costa Rican Pacific coast is the existence of a seasonal upwelling area located in the Gulf of Papagayo, close to the border with Nicaragua (e.g. Cronin et al. 2002; Fiedler 2002; Amador et al. 2006; Alfaro & Cort es 2012), and a transient upwelling event in the vicinity of the Gulf of Nicoya (Brenes et al. 2003). "
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