Indonesia reef study pairs monitoring methods with resident views

Researchers from Hasanuddin University assessed coral reef conditions across three islands in Indonesia's Spermonde Archipelago using underwater photography and drone surveys, and gathered local perspectives on reef conditions and restoration, according to a study published in the journal Anthropocene Coasts. The archipelago is home to 120 coral islands and is described as a coral biodiversity hotspot in Indonesia. Live coral cover there has declined from 45% to 28% over the past two decades, the study reported.

The team compared three monitoring approaches: line intercept transects (LIT), which record substrate along measured lines; underwater photo transects (UPT), which estimate substrate coverage using transect photographs; and drone surveys, which capture broader reef views from above the water. Until now, no systematic comparison of these methods had been conducted in the archipelago, according to the report. Jamaluddin Jompa, a professor in the Department of Marine Science at Hasanuddin University, said the aim was "to provide an evidence-based foundation for conservation policies while enhancing the adaptive capacity of local communities and stakeholders in responding to evolving ecological challenges in the Spermonde Archipelago."

The three islands differed in water quality: Lae-Lae Island had highly turbid water, Kodingareng Lompo Island had moderate water clarity and Lanyukang Island had relatively clear water. The LIT and UPT results showed better reef conditions at Kodingareng Lompo and Lanyukang, where live hard coral remained relatively abundant, while the more turbid waters of Lae-Lae had more rock, coral rubble and dead coral covered with algae. Drone mapping provided a broader view of the reefs but could not reliably distinguish different substrate types in Lae-Lae's turbid waters, according to the study.

The study reported that LIT and UPT provide detailed information about reef conditions but require trained divers and specialized equipment. Drone mapping can survey larger areas without experienced divers but does not provide the same level of detail. The researchers stated that the findings highlight the complementary value of drone observations and underwater surveys.

Focus group discussions with 33 residents showed that local communities were aware of the decline in coral reef conditions, although their understanding of its causes was more limited, the study reported. The researchers also reported limited community readiness to participate in conservation efforts. They suggested that training and institutional support could strengthen local communities' role in protecting the reefs.