Researchers have retrieved autonomous reef monitoring structures (ARMS) placed in Palau's 'deep reefs' to study biodiversity in the mesophotic zone.
Key facts
- •The 'deep reefs' or mesophotic zone ranges from approximately 30 to 150 meters below the ocean surface.
- •Technical diving at 100 meters is limited to five to seven minutes of bottom time due to safety risks like decompression sickness.
- •Luiz Rocha and his team deployed ARMS in Palau, Guam, the Marshall Islands, and French Polynesia between 2016 and 2018.
- •The retrieved ARMS were analyzed at the Palau International Coral Reef Center to identify morphospecies and collect DNA samples.
- •Researchers are investigating whether deep reefs serve as a refuge for species from shallower coral reefs.
Zoologist Luiz Rocha and a team of researchers recently retrieved scientific structures from the deep reefs of Palau, an island nation in the western Pacific. These structures, known as autonomous reef monitoring structures (ARMS), were placed at depths of up to 100 meters in 2016 to collect data on mesophotic coral ecosystems. The project aims to provide a baseline understanding of these under-studied environments, which exist between 30 and 150 meters below the surface.
Understanding the Mesophotic Zone
Mesophotic coral ecosystems, often called 'deep reefs,' exist in a twilight zone between bright surface waters and the deep ocean. Unlike shallow reefs that rely heavily on photosynthesis, deep reefs are cooler and dimmer, requiring specialized species to survive. Scientists currently have significant knowledge gaps regarding these ecosystems, including their food chains, energy sources, and potential role as refuges for shallow-water species.
The Role of ARMS Technology
ARMS are stacks of PVC plates that act as standardized 'hotels' for marine life. By leaving these structures on the seafloor for years, researchers allow local larvae and organisms to colonize them, creating a stable, diverse mini-reef. This method allows scientists to collect and compare biodiversity across different locations and depths in a consistent manner, overcoming the limitations of short, high-risk technical dives.
Analyzing the Collected Data
After retrieving the structures from Palau, the team transported them to the Palau International Coral Reef Center for analysis. Researchers disassembled the plates to document and sample various organisms, including sponges, sea squirts, octocorals, and bryozoans. The team is now sequencing DNA from these samples to identify species and determine if they are new to science.
Timeline
- 2016Luiz Rocha and colleagues began deploying ARMS in the deep reefs of Palau and other Pacific locations.
- 2016-2018The team continued to install ARMS at various depths to compare deep and shallow reef ecosystems.
- May 2024Researchers retrieved the structures from the deep reefs of Palau after nearly a decade of colonization.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by Wired.
