The study, published in the journal Nature Communications, provides new insights into the trophic ecology of corals and their role in marine ecosystems.
Corals are marine invertebrates that build hard skeletons out of calcium carbonate. They live in colonies, forming coral reefs that provide habitat for a diverse range of marine life. Corals are typically thought of as autotrophic organisms, meaning they produce their own food through photosynthesis using symbiotic algae called zooxanthellae.
Zooxanthellae live within the coral's tissue and provide the coral with essential nutrients through photosynthesis. In exchange, the coral provides the zooxanthellae with a protected environment and access to nutrients.
The traditional view of coral nutrition has been that zooxanthellae provide the majority of the coral's nutritional requirements, with the coral obtaining the rest of its nutrition from waterborne particles and occasional predation. However, the new study suggests that corals may be more reliant on hunting than previously thought.
To quantify the relative contributions of photosynthesis and predation to coral nutrition, the researchers used a combination of field experiments, laboratory measurements, and mathematical modeling. They studied two common species of corals, Acropora millepora and Pocillopora damicornis, in the waters around Lizard Island on the Great Barrier Reef in Australia.
The researchers found that corals consumed zooplankton and other small organisms at rates that were significantly higher than previously reported. They estimated that corals obtained 10-15% of their total nutrition from predation during the day, and up to 90% at night when photosynthesis was not occurring.
For the coral species Acropora millepora, the researchers estimated that predation could provide up to 15% of the colony's total carbon budget during the day, which increases to 45 % at night. For Pocillopora damicornis, predation provides 12% of the total carbon during the day and 30% at night.
The study's findings suggest that corals may be more adaptable and flexible in their feeding strategies than previously thought. While photosynthesis remains an important source of nutrition for corals, predation may play a more significant role in their survival and growth, particularly in nutrient-poor environments or during periods of stress.
Understanding the nutritional requirements and feeding strategies of corals is crucial for managing and conserving coral reef ecosystems. The new study provides valuable insights into the trophic ecology of corals and their role in marine food webs, which can help inform conservation efforts and strategies for protecting these important ecosystems.
