Thailand's first aerial drone survey for coral reef bleaching research
On 2 June 2021, Asst. Prof. Thon Thamrongnawasawat Ph.D., an expert in marine ecology and dean of the Faculty of Fisheries at Kasetsart University, created a post on his personal Facebook page “Thon Thamrongnawasawat” discussing the use of drones to study the incidence of coral reef bleaching. The Faculty of Fisheries at Kasetsart University (Department of Marine and Coastal Resources) together with PTT Exploration and Production Public Company Limited (“PTTEP”) and its subsidiary AI and Robotics Ventures Co., Ltd. (“ARV”), through ARV’s specialized business arm called, Skyller, successfully conducted Thailand's first drone survey of coral bleaching, in the study of an area known as "Hin Thuy Hoi," a coral reef near Koh Mun Nai, one of Rayong province's finest coral reefs.
Drone surveys require meticulous planning. In brief, the first step requires sending drones to identify locations where coral bleaching is located. Once an approximate location is identified, the drones are flown back to base for a change of batteries, before being dispatched again. A standard drone flight lasts for approximately 20 minutes, and flight path management is critical to perform the task most efficiently. For the flight to the specified target location, the drone will circle the area of interest, to do a “Detailed Survey,” the timing of which is crucial as this flight must also be conducted during the short window of lowest tide.
“Once the drone flies to the target destination during lowest tide which occurs around 12 AM – 1 PM, it is necessary to take both vertical and oblique pictures because of the light reflection from the ocean surface. Next, the Ground Truthing process begins, which involves doing field surveys on foot, as well as underwater with divers, during which the large drone will be mapping to a 2-centimeter level of detail. Lastly, we will investigate the bleached corals closely, and create a coral reef map that identifies the specific number of corals.” Dr. Thon said.
“Drones have tremendous potential. They serve a variety of purposes such as exploration, tracking, research, conservation, and so on. Drones are the ideal tool for navigating Thai waters as they unlock numerous constraints. Employing drones saves time, manpower, and money in a mission that requires scanning vast regions in a short period, such as coral bleaching.”
“The difficulty with drone surveys is that they require a great deal of flight experience due to the unpredictable nature of weather, waves, winds, and tides. Most of the time the teams need to improvise promptly on-site within a short operational window of two hours, because once the ocean tide rises from lowest levels, the mission must be aborted. The opportunity will only open 2-3 times per month which is when the tide is at its lowest; if we miss a window of opportunity, then we may need to wait for an entire month.” Dr. Thon added.
The loss of single-celled algae called “Zooxanthellae” that dwells inside the tissue of the coral is the reason that causes “coral bleaching.” Coral tissues are normally not colored; the tissue is just a transparent organ that conducts photosynthesis and offers minerals that aid with coral growth. If the water temperature increases by just 1 to 2 degrees celsius for three weeks in a row, the corals are stressed and the algae that feed and color the coral leave to other areas to survive. As a consequence, the phenomenon of coral bleaching ensues. However, if the ocean temperature lowers, corals may be able to regrow and proliferate.
Most marine scientists agree that coral bleaching events may be a significant indicator that water temperatures are gradually increasing. Normally, saltwater both absorbs and reflects solar heat. Water temperature is most likely a significant indication of the severity of global warming. Aside from global warming, there are additional variables to consider, such as changes in ocean salinity or contamination from other causes.
Scientists have observed extensive coral reef bleaching throughout the Pacific Ocean. There have been reports of coral bleaching since 1984. Bleaching was reported in Thailand in 1991, 1995, and 1998. Moreover, according to records for the Gulf of Thailand, some locations have been reported to have 80-90 percent coral mortality. Coral reefs are one of the ocean's most precious ecological systems. Many aquatic creatures rely on them for survival, and they are a measure of the richness of marine diversity. If the ocean's “forests” are destroyed, there is a direct impact on aquatic life, as well as on the human societies which depend on them for livelihood.
Reference: ผู้จัดการออนไลน์ (2021, June 3). โชว์ภาพจากโดรนสำรวจ “ปะการังฟอกขาว” ครั้งแรกของไทย!! Https://Mgronline.Com/. https://mgronline.com/greeninnovation/detail/9640000053499