The world's fourth massive coral bleaching event is underway, but well-connected reefs could have a greater likelihood of recovering

The world's coral reefs are like underwater cities teeming with fish and marine lifetime of all types. Coral reefs cover lower than 1% of the ocean, but they support An estimated 25% of all marine speciesincluding many vital fish species. The economic value of the services provided by these complex ecosystems is over 3.4 billion US dollars annually within the USA alone

Today, rising sea temperatures threaten the survival of many reefs. If the ocean water stays too warm for too long, corals push out the colourful symbiotic algae called zooxanthellaethat live of their tissues – a process called coral bleaching. These algae provide food for the corals, so bleached corals are vulnerable to starvation and disease and may die if the water doesn't cool quickly enough.

With global ocean heat at record levelsScientists have confirmed that a world coral bleaching is underwaySince the start of 2023 Corals are dying within the Indian, Pacific and Atlantic Oceans, each north and south of the equator.

The current bleaching event in the broader Caribbean region is longer and more severe than any previous bleaching event for the reason that first global event in 1998. I’m studying large-scale climate and ocean dynamics and analyze how biological connections between coral reefs – sometimes extending over great distances – might help reefs recuperate from heat stress.

Reef relationships

As the oceans rapidly evolve, scientists are working to develop response strategies, including making corals more heat-resistant, restoring damaged areas with healthy corals, moving coral nurseries to cooler areas, and operating coral nurseries. Breeding “super corals”“that are more resilient to those stresses; and the development natural chemical signals And Sound signals to draw coral and fish larvae to damaged reefs.

Many fish species present in coral reefs play a crucial role in maintaining the health of those communities. For example, algae compete with corals for space and light-weight and infrequently take over reefs after coral bleaching events.

Corals stay healthier and recuperate faster when surrounded by fish that eat various kinds of seaweed, akin to Parrotfish, surgeonfish and rabbitfishBecause of their role, these species are sometimes referred to collectively as grazers.

Sea cucumbers – leathery bottom dwellers, distantly related to starfish and sea urchins – are also vital partners of the reefs. They feed on bacteria and other organic materials in marine deposits and thus clean the environment of the reefs.

My colleague from Georgia Tech Mark Hay recently published a study showing that removing sea cucumbers from reef communities led to a rise in organic waste and a 15-fold increase in coral deathsProtecting sea cucumbers, that are overfished as a food source, could contribute to the health of coral reefs.

The role of ocean connectivity

Coral reefs should not isolated outposts. When fish and corals spawn, they release thousands and thousands of larvae that drift with the present and are exchanged across the reefs. Mixing and transport processesThis exchange represents the connection between coral reefs.

Some reefs supply larvae to many others. Other reefs are more isolated, so scientists might have to artificially introduce larvae to assist reefs recuperate from coral bleaching and other threats.

Studies show that well-connected reefs recuperate faster from stresses akin to bleachingThe abundant supply of coral and fish larvae washed up from distant by ocean currents helps restore bleached areas and maintain diverse reef communities. Maintaining this connectivity is critical to protecting reefs.

But measuring connectivity is time-consuming and expensive. Researchers collect coral samples from reefs which may be connected and analyze the corals' DNA to reconstruct their genetic history, constructing an image of how strongly different populations are connected.

We also use computer models to simulate ocean currents that carry virtual larvae from their release points to the places where they settle. But currents should not fixed in a single place like highways: their strength and direction change over time, depending on the season and yr. To study reef connectivity, multi-year model simulations have to be carried out that cover small areas intimately, which requires plenty of computational work.

Insights from machine learning

Now, machine learning offers a brand new approach to analyze reef connections. This branch of artificial intelligence enables computers to learn tasks or relationships without being explicitly instructed. Instead, they use algorithms to perform various tasks.

My research group has developed a tool that uses details about ocean currents from satellite data to generate a network of ecoregions, or areas where ecosystems are generally similar. calculates their connectivity during the last 30 to 40 yearsWe then discover higher connected reefs using PageRank centrality – the algorithm developed by Google to measure the recognition of internet sites.

Once we have now defined a network of ecoregions, we are able to determine how “popular” – that’s, how connected – known reefs are. And we are able to check that our algorithms are working well by observing whether “popular” reef communities contain more diverse and healthy coral populations.

We have found that in The Coral Triangle of Southeast Asia – the biggest biodiversity hotspot on Earth – periodic fluctuations between the El Niño and La Niña climate patterns promote biodiversity and are more likely to have done so. within the last 5 to 7 million years. Connectivity during El Niño events may be very different from that in La Niñas because ocean currents are different. These dynamics help reefs by ensuring that they receive larvae from many various locations in several years.

Understanding which coral and environmental characteristics help reefs grow to be more resilient and linking this information to connectivity networks opens up latest opportunities to assist corals survive longer. Together, these approaches show how and where monitoring and restoration efforts ought to be prioritized.

In the long run, the one approach to stop coral death and protect reefs which are home to a lot marine life is Limiting water pollution and mitigate climate change. But localized measures to make reefs healthier should buy them a while and maybe make them more resilient to warming oceans.