How scientists stumbled onto a new way to monitor underwater habitats

Assessing coral reef environments using standard scuba diving methods is not always feasible because of time, financial, and safety concerns. Because of this, scientists at the University of the Philippines-Marine Science Institute (UP MSI) are busy developing the relatively low-cost A Rapid Assessment Instrument for Coastal Benthic Habitats (ARAICOBEH) system.

What's in a name?

"The name comes from the descriptors that answer the questions "Where is it used?" (coastal benthic habitats), "What is its intended use?" (rapid assessment), and "What is it?" (monitoring tool). We thought of the name first then rearranged it to fit an easy to remember acronym. It took me two nights to figure it out," says Patrick Cadeliña, one of the researchers developing the ARAICOBEH.

"I was really looking for an acronym that is easy to remember and in Filipino.  It kind of just snapped when i rearranged 'rapid assessment for benthic habitats'... and everything fell into place,” he adds, laughing.

Make no mistake, though: despite its whimsical name, ARAICOBEH was designed with a very serious purpose in mind.

"Conventional coral monitoring methods require scuba diving, but scuba diving is costly, takes time to set up, requires surface interval [non-diving days], and not all coastal areas in the Philippines have a compressor and dive tanks. With ARAICOBEH, we decrease the survey time, costs, and risk of accidents. We also bring less equipment and cover more area than scuba," Cadeliña explains.

What it's made of

A system that's greater than the sum of its parts, the ARAICOBEH system is composed of an underwater camera (to take the survey photos), hard plastic fin (for stability), dive computer (to record the camera's current depth), single beam echo sounder (to measure the depth of the benthos), and GPS (to geotag the survey photos), all attached to a weighted pole. When put together, the system allows researchers to quickly survey underwater environments and record the GPS coordinates of the study site, all without leaving the boat.

"The idea for ARAICOBEH started in May 2014 during the Benham Rise survey. The reconnaissance device then was just an underwater camera and dive computer attached to a rope with weights and deployed to get a first look at what was down there before sending divers. We developed the first version of ARAICOBEH in late October 2014." The team is currently on their fourth version of the system.

The ARAICOBEH system has been deployed in several sites around the Philippines: Aliguay Island (Dapitan), El Nido and Taytay (Palawan), Anilao (Batangas), Sablayan (Occidental Mindoro), Island Garden City of Samal (Davao del Norte), Governor Generoso (Davao Oriental), Pujada Bay (Mati), and Panglima Sugala, SIminul, and Bongao (Tawi-tawi).

"We did a study comparing photoquadrat method [where a diver takes the underwater photos] and ARAICOBEH in three municipalities: Anilao, Sablayan, and El Nido. It turns out that in majority of the sites in those municipalities, there was no significant difference in the data that we got in terms of coral cover, coral diversity, and community composition," says Cadeliña.

Who's behind ARAICOBEH

The team is composed of Dr. Alette Yniguez, Dr. Cesar Villanoy, Caryl Benjamin, and Patrick Cadeliña of UP MSI and funded by the Department of Environment and Natural Resources (DENR) under the Coral Reef Visualization and Assessment (CORVA) Project and the Department of Science and Technology (DOST) under the National Assessment of Coral Reef Environments (NACRE) Program.

Challenges and limitations

As with all data-gathering methods, there are pros and cons to the ARAICOBEH. "Our biggest problem is the rapid change in depth, as the echo sounder stops measuring for a while so we're temporarily blind, plus the chance of the ARAICOBEH getting stuck. There's also the problem of identifying the corals. The distance of the camera to the bottom is not consistent, with some corals being deeper than others so we cannot identify them to genus level. Because of this, we classify the corals according to coral life form, which other standard monitoring methods also use." — All photos courtesy of the UP MSI's Biological Oceanography and Modeling of Ecosystems (BIOME) Laboratory, headed by Dr. Alette Yniguez/TJD, GMA News