Impact of Eastern Caribbean Circulation Seasonality on two Reef Organisms
Abstract
The variability of the Caribbean current is under the influence of the fresh water input from the Orinoco and Amazon rivers. Sea Surface Salinity maps of the eastern Caribbean show the seasonal extension of the riverine fresh water across the Caribbean basin, from August to December (wet season). The plume is divided into two main cores: one flows into the Caribbean Sea mostly through the Grenada Passage where it merges with the Caribbean Current while the other core is formed further north by advection of the river plume by the North Brazil Current rings. Due to the presence of fresh water the Caribbean Sea mesoscale activity is strongly increased during the wet season. Therefore, both coral reef ecosystems and coastal flows are under the scope of the large scale flow seasonality. The impact of the flow mesoscale seasonality on reef organisms is studied through two reef organisms: (1) Reef-building coral: Genetic analyzes show that populations of the Caribbean reef-building coral, Acropora palmata, have experienced little or no recent genetic exchange between the western and eastern Caribbean. Western Puerto Rico is identified as an area of mixing between the two subregions. Using a bio- physical coupled model accounting for larvae life history traits, we verify the plausibility of a present day oceanographic barrier caused by the Caribbean Current seasonal variability in the vicinity of Mona Passage. (2) Grouper: Several grouper species form spawning aggregations at the shelf edge of the US Virgin Islands starting at the end of the wet season in December. Using ADCP current measurements and numerical simulations, unusual large 'dispersion' pulses are shown to be associated with the presence of sub-mesoscale coherent features more likely to be formed during the wet season. Spawning occurring during the dry season (January to April) is mostly tide driven, suggesting a limited dispersal.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2008
- Bibcode:
- 2008AGUSMOS33B..04C
- Keywords:
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- 0439 Ecosystems;
- structure and dynamics (4815);
- 4220 Coral reef systems (4916);
- 4255 Numerical modeling (0545;
- 0560);
- 4512 Currents