Cryptic Coral Reef Organisms! (What Are Those?)


Editor’s Note: Alison Green, senior marine scientist for The Nature Conservancy, recently traveled to Papua New Guinea to see cutting-edge marine work by the U.S. National Oceanic and Atmospheric Administration (NOAA) in the Coral Triangle, the most biodiverse marine region on Earth. Also read her first post from Papua New Guinea on sea-surface monitoring and climate change in the Coral Triangle.

There are many ways to monitor coral reefs. The traditional way is to count corals and reef fishes that are easy to see. But this method only accounts for a small proportion of the 1 million to 9 million species estimated to occur on coral reefs.

So NOAA recently developed instruments for monitoring cryptic coral reef organisms as part of the international Census of Marine Life. These instruments (called Autonomous Reef Monitoring Structures or ARMS) provide habitat for an extraordinarily diverse range of cryptic reef organisms such as sponges, sea squirts, sea stars, worms, shrimps and crabs, sea snails and octopus.


When deployed on coral reefs for up to two years, ARMS provide information on the biodiversity of cryptic reef organisms that you can’t normally see, and preliminary results from Hawaii and Australia suggest that they will lead to the discovery of an outrageous number of new coral reef species.

The ARMS  are also expected to provide valuable information on changes in biodiversity associated with climate change and ocean acidification. To date, almost 400 ARMS have been deployed at 40 locations in the Pacific, Indian and Atlantic Oceans.

This week, we installed nine ARMS on coral reefs in Kimbe Bay, Papua New Guinea. These are the first of these instruments to be deployed in the Coral Triangle, the center of marine biodiversity. If these devices are discovering unknown biodiversity in other regions, imagine what they will find in the Coral Triangle!

(Image: (1) Dive master from Walindi Plantation Resort helps NOAA install ARMS in Kimbe Bay, Papua New Guinea. Credit: Mark Eakin, NOAA. (2) ARMS deployed on the reef in Kimbe Bay. Image: Mark Eakin, NOAA.)

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  1. Can you name some organisms that are in the Great Barrier Reef in Australia?
    Thank you.

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