Primary production in coral reefs, Key players and adaptive strategies to natural environmental variations

Coral reef ecosystems sustain their high productivity in an oligotrophic environment by the efficient recycling of nutrients and tight benthic-pelagic coupling. The basis for productivity within coral reefs is the primary production, which is accomplished by diverse benthic photosynthetic organisms and, to a minor contribution, by phytoplankton in the waters aloft. Photosynthesis is determined by the availability of light, influenced by water depth and turbidity, and the availability of inorganic nutrients, essential for the organic synthesis of vital substances like amino acids. Benthic photosynthesis in coral reefs is characterised by the high abundance of manifold zooxanthellae bearing hosts, in particular scleractinian corals. Findings of the following chapters are presented from the organism to the ecosystem level (chapter 1-5), concerning organic matter recycling (nutrient availability) and energy conversion (light availability and photosynthesis) within a coral reef ecosystem. Nutrient and light availability vary likewise between ecosystems and are comparatively investigated at the Similan Islands in the Andaman Sea of the Indian Ocean (chapter 6-8), concerning environmental conditions, benthic community composition, primary production and heterotrophy.