New Research Explains the Mystery of Coral Reef Growth
A new study from the University of Southampton has provided insight into how coral reefs thrive in nutrient-poor waters, a phenomenon that has puzzled scientists since Charles Darwin’s time. The research, led by Professor Jörg Wiedenmann, head of the Coral Reef Laboratory at the University of Southampton, reveals that corals feed on microscopic algae living within their cells, accessing a previously unknown nutrient source. The findings solve the long-standing mystery known as Darwin’s Paradox of Coral Reefs.
Coral reefs are vital ecosystems that support a wide range of marine life and provide resources to half a billion people worldwide. However, they are often found in areas with low nutrient levels, leading to the question of how they are able to flourish. This research shows that the corals actually farm and feed on their symbiotic algae, which produce carbon-rich compounds through photosynthesis. These compounds are then transferred to the corals for energy generation.
The study was conducted using a series of long-term experiments at the University of Southampton’s Coral Reef Laboratory, as well as fieldwork in remote coral reef atolls in the Indian Ocean. The researchers found that corals can actually digest some of their symbiotic algae to access nitrogen and phosphorus, which are essential for their growth. This mechanism allows corals to grow quickly, even in nutrient-poor waters.
Dr Cecilia D’Angelo, associate professor of Coral Biology at Southampton and one of the lead authors of the study, explains that the researchers observed that corals were able to grow well even when not fed. This led them to analyze the process and discover the missing piece of the puzzle.
The researchers used isotopic labeling techniques to trace the movement of nitrogen between the coral host and the symbiotic algae. The experiments showed that the nitrogen atoms that sustained coral growth were derived from dissolved inorganic nutrients that were fed to the algae.
Professor Paul Wilson, a paleoceanographer at the University of Southampton, explains that this technique allowed the researchers to demonstrate conclusively how the corals obtain their nutrients.
The study also analyzed corals growing around islands in the Indian Ocean, some with and without seabird populations. It found that coral growth was significantly greater in areas with seabirds, which provide nutrients through their excrement. This further supports the researchers’ findings that corals feed on their symbiotic algae to supplement their nutrition.
The research has important implications for coral reef conservation, as excessive nutrient enrichment can damage corals. Additionally, the study suggests that global warming may further reduce nutrient availability for corals, putting reefs at risk.
Overall, this study provides valuable insight into the mechanisms behind coral reef growth and will help inform future conservation efforts to protect these vital ecosystems.