The Effect of Irradiance and Zooplankton on the Stable Carbon Isotopic (d13C) Composition on Scleractinian Corals

EPA Grant Number: U914955
Title: The Effect of Irradiance and Zooplankton on the Stable Carbon Isotopic (d13C) Composition on Scleractinian Corals
Investigators: Grottoli-Everett, Andrea G.
Institution: University of Houston
EPA Project Officer: Manty, Dale
Project Period: January 1, 1996 through December 7, 1999
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text |  Recipients Lists
Research Category: Fellowship - Oceanography , Aquatic Ecosystems , Academic Fellowships


The objective of this research project is to evaluate the effect of solar irradilance and plankton on delta13C levels in coral skeletons to reconstruct paleoclimate (climate of past ages) changes related to cloud cover and the extent of upwelling events in the eastern Pacific Ocean.


The proposed experiments were designed to test the following hypotheses: (1) as irradiance increases, skeletal delta13C increases; and (2) as plankton levels increase, skeletal delta13C decreases. A controlled tank experiment was conducted in Hawaii to grow coral fragments of Porites compressa and P. lobata under specific light and zooplankon regimes for 4 months. The resulting skeletal material will be extracted, and the delta13C levels will be analyzed. A multiple linear regression of the data will be used to assess the association between skeletal delta13C, light, and plankton. The resulting predictive model will facilitate reconstruction of past light and plankton levels based on patterns of the skeletal delta13C signature. The model was validated by conducting a field experiment (similar to the tank experiment); its range of applicability was tested by conducting a similar field experiment in Florida. The model will be used to reconstruct cloud cover and upwelling events from published coral isotope records. The complete reconstruction of tropical paleoclimates and its incorporation into global climate models (GCMs) are essential to improving the reliability of GCMs and their powers of global climate prediction.

Supplemental Keywords:

fellowship, stable carbon isotopic composition, scleractinian corals, solar irradiance, plankton, global climate modesl, GCMs., RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Chemistry, climate change, Air Pollution Effects, Aquatic Ecosystem, Monitoring/Modeling, Ecological Risk Assessment, Atmosphere, environmental monitoring, environmental measurement, meteorology, climatic influence, climate, global change, ecosystem indicators, climate models, UV radiation, aquatic ecosystems, environmental stress, plankton, coastal ecosystems, global climate models, coral reef communities, climate model, ecosystem stress, ecological models, solar irradiance, atmospheric chemistry, climate variability