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Inter-disciplinary study of flow dynamics and sedimentation effects on coral colonies in Faga'alu Bay, American Samoa : oceanographic investigation summary


Description:

Title:
Inter-disciplinary study of flow dynamics and sedimentation effects on coral colonies in Faga'alu Bay, American Samoa : oceanographic investigation summary
Alternate Title:
Oceanographic investigation study
CRCP Project #417
Author(s):
Vetter, Oliver
Vargas-Ángel, Bernardo, 1965-
United States, National Marine Fisheries Service
United States, National Oceanic and Atmospheric Administration,
Coral Reef Conservation Program (U.S.)
Corporate Name:
United States, National Marine Fisheries Service
United States, National Oceanic and Atmospheric Administration,
Coral Reef Conservation Program (U.S.)
Dates of Publication:
2013
Abstract:
Water flow in Faga'alu bay was investigated using a year of data collected from in-situ oceanographic equipment. Waves and tides were measured on the forereef and reef flat and the outflow currents were measured in the reef pass. Flow dynamics in the bay are predominantly forced by waves breaking over the shallow reef to the south of the channel, which force the majority of the water to exit the bay through the single main channel in the reef. Wave height and tidal height were both strong influences on flushing time however due to the volume of water forced over the reef during wave events flushing rates increase proportionally with wave height. Flushing time in the lagoon was calculated to be approximately 33 hours during low wave events, decreasing to less than 2 hours during the highest wave event of the year. The bay is relatively enclosed, limiting the swell window and large wave events are uncommon. The largest wave event of the year had a peak significant wave height (Hsig) of less than 1.6 m which is low for the region. Since flushing is strongly wave dependent pollutants and sediment have a greater likelihood of settling and causing harm to the ecosystem, compared to bays or estuaries with better flushing mechanisms. Comparing these oceanographic data with the biological component of this project suggests that in general areas with better flushing, and subject to higher wave energy, were found to be healthier than those sheltered from incident waves. The interest in Faga'alu's watershed may be well advised since the low energy in the bay may require more focused attention on storm water management compared with other watersheds, in order to limit run-off and mitigate damage caused by sedimentation and pollution"--Abstract.
Keywords:
Coral colonies
Coral reefs and islands
Effect of sediments on
Effect of water waves on
Health
Ocean currents
Ocean waves
Sedimentation and deposition
Tides
Place Keywords:
American Samoa
Local Corporate Name:
NMFS (National Marine Fisheries Service)
CoRIS (Coral Reef Information System)
Type of Resource:
Miscellaneous
Note:
Water flow in Faga'alu bay was investigated using a year of data collected from in-situ oceanographic equipment. Waves and tides were measured on the forereef and reef flat and the outflow currents were measured in the reef pass. Flow dynamics in the bay are predominantly forced by waves breaking over the shallow reef to the south of the channel, which force the majority of the water to exit the bay through the single main channel in the reef. Wave height and tidal height were both strong influences on flushing time however due to the volume of water forced over the reef during wave events flushing rates increase proportionally with wave height. Flushing time in the lagoon was calculated to be approximately 33 hours during low wave events, decreasing to less than 2 hours during the highest wave event of the year. The bay is relatively enclosed, limiting the swell window and large wave events are uncommon. The largest wave event of the year had a peak significant wave height (Hsig) of less than 1.6 m which is low for the region. Since flushing is strongly wave dependent pollutants and sediment have a greater likelihood of settling and causing harm to the ecosystem, compared to bays or estuaries with better flushing mechanisms. Comparing these oceanographic data with the biological component of this project suggests that in general areas with better flushing, and subject to higher wave energy, were found to be healthier than those sheltered from incident waves. The interest in Faga'alu's watershed may be well advised since the low energy in the bay may require more focused attention on storm water management compared with other watersheds, in order to limit run-off and mitigate damage caused by sedimentation and pollution"--Abstract.
2013
NMFS (National Marine Fisheries Service)
CoRIS (Coral Reef Information System)
Library
1658
URL:
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