What is coral dating
The bands in the coral’s shell can change in thickness with changes in temperature, water clarity, or nutrient availability, so while each band can record the season’s climate, the interpretation of the record depends on how the three factors are related.Cool water rising from the ocean floor brings extra nutrients in many areas, so the shells are often thicker when the water is cool. Scientists have to couple their observations of patterns in the seasonal bands to other measurements, including modern observations of coral growth, to determine what the bands say about climate change.Vibrant coral reefs harbor diverse communities of life in the tropical oceans.Like trees, corals produce annual rings that store a record of past conditions.(X-ray image courtesy Thomas Felis, Research Center Ocean Margins, Bremen)Coral can also tell scientists when heavy rains or floods carried extra sediment into the ocean.Sediment in the water can change the color of the coral as it absorbs elements from the land.Further, reef coral has a symbiotic relationship with algae that use photosynthesis to produce energy.
They can only tell scientists about climate in warm, tropical waters.Chemical analyses reveal details about past temperature, nutrient availability, salinity, and other information.(Photograph courtesy NOAA Photo Library) One of the most significant clues to climate in coral comes from the chemistry of the bands.The chemicals in each layer reflect conditions in the ocean when the layer formed.Like the scaly coverings of foraminifera and other marine organisms, the ratio of heavy and light oxygen in coral growth bands provide a record of temperature and rainfall during the growing season.