Coral reefs are one of the most diverse and productive ecosystems on the planet, yet they have suffered tremendous losses due to anthropogenic disturbances and are predicted to be one of the most adversely affected habitats under future climate change conditions. Coral reefs can be viewed as microbially driven ecosystems that rely on the efficient capture, retention, and recycling of nutrients in order to thrive in oligotrophic waters.
Nitrogen fixation occurs on coral reefs, by cyanobacterial mats, bacteria and reef-associated seagrasses, and in other habitats, such as seagrass meadows.726,727 Coral reefs thrive under low-nutrient conditions 266,728,729 by fixing nitrogen from the atmosphere and efficient recycling of nitrogen and carbon.317 The productivity of zooxanthellae is highly dependent on available nitrogen, so efficient nitrogen cycling within the coral holobiont (Section 3.4.6) may be crucial for sustaining primary productivity in coral ecosystems.730 Elevated temperatures stress corals by limiting the efficiency of their internal nutrient cycling.731 The presence of excess nutrients in coral ecosystems can favour competitors like macroalgae over corals.732
As we can see from the illustration, Reef Ecosystem Nutrient Exchange Mechanisms has many fascinating aspects to explore.
Coral reefs are riddled with holes and tunnels of all sizes. From 50 to 75% of the reef · volume can be made up of these voids (Ginsburg, 1983). ... Andrews and Muller, 1983 ; Szmant-Froelich, 1983) . I suggest that 'burps' of nutrient enriched water exit these holes and provide benthic
