Patterns and controls of calcification in tropical reefs: from skeletal microstructure to reef framework

Abstract

The global distribution of coral reefs is mainly limited by temperature and light; further factors controlling reef development include nutrients, salinity, oxygen concentration and aragonite saturation state. The most vigorous reef growth can be found within the tropics, where corals build a massive 3-dimensional carbonate framework. However, in some tropical areas reefs are confronted with strongly fluctuating or marginal environmental conditions. Both can hamper reef formation and prevent framework development. In such areas coral growth and reef functioning can be studied under sub-optimal conditions. Investigating the potential of reefs to adapt to such unfavorable environmental conditions provides further insight on the fate of coral reefs in a changing climate. Here it was investigated how strong environmental variability due to internal waves (changing inter alia temperature, pH, nutrients) affect reef development in the Andaman Sea. Moreover it was investigated how these environmental fluctuating conditions reflect at the skeletal level by studying growth properties (linear extension, density, calcification) and skeletal proxies for temperature.