Geology topics

C. Langdon

Publications and source records attributed to C. Langdon.

3 recordsLinked to original sources

USGS2011

Productivity of a coral reef using boundary layer and enclosure methods

The metabolism of Cayo Enrique Reef, Puerto Rico, was studied using in situ methods during March 2009. Benthic O 2 fluxes were used to calculate net community production using both the boundary layer gradient and enclosure techniques. The boundary layer O 2 gradient and the drag coefficients were used to calculate productivity ranging from −12.3 to 13.7 mmol O 2 m −2 h −1 . Productivity measurements from the enclosure method ranged from −11.0 to 12.9 mmol O 2 m −2 h −1 . During the study, the mean hourly difference between the methods was 0.65 mmol O 2 m −2 h −1 (r 2 = 0.92), resulting in well‐reconciled estimates of net community production between the boundary layer (−33.1 mmol m −2 d −1 ) and enclosure (−46.3 mmol m −2 d −1 ) techniques. The results of these independent approaches corroborate quantified rates of metabolism at Cayo Enrique Reef. Close agreement between methods demonstrates that boundary layer measurements can provide near real‐time assessments of coral reef health.

Puerto Rico↗

USGS2005

Comment on "Coral reef calcification and climate change: The effect of ocean warming"

McNeil et al. [2004] attempt to address an important question about the interactions of temperature and carbonate chemistry on calcification, but their projected values of reef calcification are based on assumptions that ignore critical observational and experimental literature. Certainly, more research is needed to better understand how changing temperatures and carbonate chemistry will affect not only coral reef calcification, but coral survival. As discussed above, the McNeil et al. [2004] analysis is based on assumptions that exclude potentially important factors and therefore needs to be viewed with caution. Copyright 2005 by the American Geophysical Union.

Geophysical Research Letters↗

USGS1999

Geochemical consequences of increased atmospheric carbon dioxide on coral reefs

A coral reef represents the net accumulation of calcium carbonate (CaCO3) produced by corals and other calcifying organisms. If calcification declines, then reef-building capacity also declines. Coral reef calcification depends on the saturation state of the carbonate mineral aragonite of surface waters. By the middle of the next century, an increased concentration of carbon dioxide will decrease the aragonite saturation state in the tropics by 30 percent and biogenic aragonite precipitation by 14 to 30 percent. Coral reefs are particularly threatened, because reef-building organisms secrete metastable forms of CaCO3, but the biogeochemical consequences on other calcifying marine ecosystems may be equally severe.

Science↗