Uncovering Coral Larvae’s Adaptive Strategy Against Climate-Driven Bleaching

According to a study published in PLOS Biology, coral larvae can resist bleaching under high temperatures by reducing their metabolism and enhancing nitrogen uptake. This research sheds light on coral responses to thermal stress during their early life stages—an area that has seen limited study.

Coral bleaching is triggered by high ocean temperatures, disrupting the crucial relationship between corals and their symbiotic algae. As global temperatures increase, understanding these mechanisms is vital for coral conservation.

In this study, researchers at the Hawai‘i Institute of Marine Biology exposed coral larvae to temperatures 2.5 °C above the ambient level, simulating anticipated climate change effects. Over a three-day period during their first week of development, the larvae and their symbiotic algae were subjected to these elevated temperatures.

The coral larvae demonstrated remarkable resilience, maintaining algal photosynthesis and the transfer of carbon-based nutrients, with no signs of bleaching. However, they exhibited a 19 % reduction in metabolism, alongside an increase in nitrogen uptake and storage—adaptations that appear to support coral survival under thermal stress.

By reducing metabolism, the coral conserves energy and resources—a strategy also observed in adult corals experiencing bleaching. The shift in nitrogen cycling appears to be an adaptation that limits nitrogen availability to the algae, helping prevent excessive algal growth and maintaining stability in the coral-algae relationship.

The effectiveness of these strategies under even higher temperatures or prolonged exposure remains uncertain. Additional research into these adaptive responses and their limitations is essential for accurately predicting coral resilience and developing strategies to protect coral reefs as ocean temperatures continue to increase.

The authors added, “This research reveals that coral larvae must invest in their nutritional partnership with algae to withstand stress, offering key insights into strategies to avoid bleaching in the earliest life stages of corals.”

Journal Reference:

Huffmyer, A. S., et al. (2024) Coral larvae increase nitrogen assimilation to stabilize algal symbiosis and combat bleaching under increased temperature. PLOS Biology. doi.org/10.1371/journal.pbio.3002875.