Geography – Coastal environments | e-Consult

The distribution of coral reefs is heavily influenced by a complex interplay of environmental factors. Firstly, temperature is paramount; coral polyps thrive in warm, stable waters between 20°C and 30°C. Areas outside this range, particularly those experiencing prolonged periods of low or high temperatures, will see reduced coral growth or coral bleaching. Secondly, light availability is crucial as corals rely on symbiotic algae (zooxanthellae) for photosynthesis. Reefs are therefore typically found in shallow, clear waters where sunlight can penetrate. Water salinity also plays a vital role; corals require stable, saline conditions. Furthermore, water movement is important for bringing nutrients and removing waste products. Reefs are often found in areas with moderate wave action, but excessive turbulence can damage coral structures. Finally, substrate availability is necessary for coral polyps to attach and grow. This typically means a hard surface, such as rock or the remnants of previous coral reefs.

Geographically, these factors explain the prevalence of coral reefs in tropical and subtropical regions, particularly around the equator. The Great Barrier Reef in Australia, the Coral Triangle in Southeast Asia, and reefs in the Caribbean are prime examples. However, even within these regions, variations in depth, water flow, and local currents lead to variations in reef distribution. The presence of continental shelves, which provide a stable base and nutrient supply, also contributes to reef formation.

In conclusion, the distribution of coral reefs is a direct consequence of a specific combination of temperature, light, salinity, water movement, and substrate availability. These factors interact to create suitable habitats for coral growth, resulting in their characteristic tropical and subtropical distribution.