Fourteen fishing cooperatives filed suit in Makassar on 29 October, seeking an emergency order to pause a planned energy survey and require expanded monitoring of the Flores Sea. Their petition cites a warm-water layer that scientists say has persisted for weeks below the surface, where ordinary satellite readings cannot detect it. A hearing is scheduled for 6 November.
Measurements from 11 autonomous profiling floats and three moored instruments show water 2.4°C (4.3°F) warmer than the seasonal average between 60 and 140 metres (197 and 459 feet) deep. The affected band stretches about 410 kilometres (255 miles) from Flores towards Savu. Surface temperatures remain close to normal, and researchers have not identified the cause.
The heat is below the surface
Elina Toijala, a Finnish oceanographer working with a marine-monitoring team in Makassar, pointed to a jagged orange band on a screen in her laboratory. “It is as if a second ocean has been laid underneath the one people can see,” she said. The instruments detected the anomaly in September; each new reading has found it in roughly the same depth range.
Toijala’s team modelled a worst-case path in which the warm layer rises by 35 metres (115 feet) before 15 December. Under that scenario, 58% of surveyed reef sites in Flores, Lembata and Alor could exceed 30°C (86°F) for at least 21 days, long enough to trigger severe coral bleaching. “This is not a forecast that the reefs will all bleach,” she said. “It is a warning that the window to prepare is short.”
This is not a forecast that the reefs will all bleach. It is a warning that the window to prepare is short.
Elina Toijala, oceanographer
Scientists do not yet know whether the heat is being carried by an unusual current, trapped by changes in the region’s layered water, or linked to a mix of processes. Anghel Dragomir, a climate modeller advising the research team, said the anomaly was too deep to explain with local sunshine alone. If it reaches the surface and persists into January, a regional model projects 10% to 15% more moisture in the strongest monsoon rain bands over parts of Nusa Tenggara. He stressed that this is a conditional scenario, not a seasonal forecast.
Lawsuit forces a deadline
Salomé Rubio, a lawyer representing the cooperatives, said the filing was meant to secure data and precautionary measures, not to claim that a company caused the warming. Fishers fear that a sudden fall in reef life would hit catches and household income just as the year-end fishing season begins. “People can’t plan around a phenomenon nobody is measuring in the places they fish,” Rubio said.
Cheryl Manuel, a spokesperson for Indonesia’s fisheries ministry, said there was “no evidence of an immediate threat to coastal settlements” and that evacuation advice was not being considered. The ministry plans to send six more profiling floats into the area. Dragomir said that would improve coverage, but might not answer the central question quickly: “The layer can shift between instruments before the next reading arrives.”
The suit also challenges an eight-week seismic survey planned by Lintas Banyu Petroleum in waters north of Flores. The fictional Indonesian producer reported first-half earnings of Rp1.9 trillion (about €104 million), up 41% from a year earlier. Its analyst, Giacobbe Martini, said the company had no equipment in the warm layer’s measured core and would follow any court order. The cooperatives want the survey paused until sampling expands.
Researchers are asking for daily public updates and more instruments across the sea before the hearing. Toijala said the next two weeks should show whether the warm band is holding its depth or moving upwards; the distinction could change the reef projections sharply. The ministry says its first additional float will be deployed by 8 November. For coastal communities, the uncertainty is already a practical problem: the water looks ordinary, but the measurements do not.
