Coral ‘nurseries’ need protection equal to that of established coral reefs

When we envision coral reefs and coral nurseries, we often picture static rock-like structures dotting the ocean floor. These underwater gardens, vital to marine life, have long been the focus of conservation efforts.

Typically, these efforts are directed at preserving existing corals and shielding them from known dangers like pollution, overfishing, and runoff from coastal populations.

However, a transformative study near Miloliʻi, on the southwestern side of Hawai’i Island, is reshaping our approach to coral conservation. The intriguing research was spearheaded by Arizona State University scientists and their collaborators.

Indigenous knowledge and modern science

At the forefront of this research is an impressive group of scientists. Together, they emphasize the significance of safeguarding marine ecosystems, both down-current and up-current of coral reefs.

These are the areas where coral larvae, the coral keiki, are more likely to flourish. The survival of these coral nurseries is key in the face of the escalating threats posed by climate change.

Rachel Carlson, an ASU affiliate scientist, is the study’s first author. She highlights the importance of integrating local, indigenous knowledge with Western science in mapping a sustainable future for coral populations.

“There’s a lot of indigenous knowledge about coral spawning and fish populations in West Hawaiʻi. In this study, we addressed an open question: how connected are coral populations between embayments along this coastline?” said Carlson.

“What we essentially found is that the major factors in helping the coral keiki, known as larvae, settle down and survive are the nearshore current and the structure of the reef.” 

Monitoring coral nurseries from above

This study addressed a critical question: the connectivity of coral populations along certain coastlines. It found that the survival of coral larvae nurseries hinges on the nearshore currents and the reef’s structure.

These larvae tend to settle in areas with larger boulders and uneven surfaces, which they find more conducive.

An exciting aspect of this research is the utilization of ASU’s Global Airborne Observatory. This specialized aircraft, equipped with advanced remote sensing technologies, has mapped seafloor features significant for coral settlement.

Greg Asner, director of ASU’s Center for Global Discovery and Conservation Science and the study’s senior author, underscores this as “foundational research” that enhances our understanding of reef connectivity and identifies potential sites for effective coral restoration.

“First, it gives us an understanding of the connectivity of different parts of reefs along our coastline and tells us the level of connectivity in the context of the birth, settlement, and growth of corals miles apart,” Asner explained.

“Second, our unique remote sensing capabilities can identify reef sites where coral restoration could be most viable in the future. Finally, these findings provide a critical building block for future restoration efforts by our ʻĀkoʻakoʻa team and collaborators,” concluded Asner.

Cultural and community engagement

The ʻĀkoʻakoʻa Reef Restoration Program, a regional initiative combining cultural leadership, education, science, and government engagement, has been instrumental in supporting this research.

Kaʻimi Kaupiko, president of Kalanihale, a non-profit managing the Miloliʻi Community-based Subsistence Fishing Area, reflects on the cultural and ecological significance of reefs.

Kaupiko states, “We as lineal descendants of the Miloliʻi area have always relied on the reef for our ʻOhana (families). Our reef is our sustenance and is of enormous cultural value to us.”

Expanding the scope of coral protection

This study brings a new perspective to reef protection strategies. Asner compares it to understanding the importance of a forest, not just individual trees.

Robin Martin is an associate professor with the ASU School of Ocean Futures. Martin echoes this sentiment, stressing that reef connectivity is an underutilized tool in global reef restoration efforts.

“In Hawai‘i and worldwide, we’re trying to figure out where we should place protections and restore areas to help reefs,” Martin said.

“This study is highly technical, but it needs to be part of that conversation and part of that work because if you aren’t protecting the up-current reefs, you are cutting off important reproductive areas.”

The research suggests that protection should encompass not only areas with dense coral coverage but also the paths through which coral larvae travel.

Coral nursery conservation efforts

This research opens new possibilities for conservation strategies, potentially extending much further than current practices.

As Asner notes, the extensive coastline of west Hawaiʻi island poses unique challenges and opportunities for coral restoration.

“These kinds of studies of connectivity, flow, and movement are needed because the west Hawaiʻi island coastline is longer than the whole circumference of any other island,” Asner said.

“We have a lot of degraded reefs along our coastline, so knowing where and how to help baby corals thrive is fundamental to the ʻĀkoʻakoʻa restoration effort.”

Understanding the movement and settlement patterns of coral larvae is fundamental to the success of the ʻĀkoʻakoʻa restoration effort.

Student contributions are vital

The involvement of students in the study represents a fusion of cultural knowledge and scientific inquiry. Kaupiko highlights this integration, emphasizing the ecological connectedness of the region and the need for comprehensive management and protection strategies.

“Our students participated in the coral study, and that also helped us to connect the dots between cultural knowledge and Western science,” said Kaupiko.

“The study supports our CBSFA by showing that our area is ecologically connected, and thus it needs to be managed and protected as one connected reef and coastline.”

In summary, this important study in Hawai‘i represents a pivotal shift in coral conservation strategies. By combining cultural insights, advanced scientific research, and community collaboration, it offers a holistic approach to preserving and restoring the delicate balance of coral ecosystems.

Their innovative work benefits the reefs of Hawai‘i while also setting a precedent for coral conservation efforts worldwide.

The full study was published in the journal Proceedings of the National Academy of Sciences.

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