The bioluminescent glow at Vieques' Mosquito Bay has ceased completely, as of October 12 2026.^[1] It is the third blackout in the bay's recorded history: the first came in 2014, the second after Hurricane Maria in 2017, and the bay recovered from both.^[2][3][4] This time, bioluminescence began declining in July 2026, and weekly plankton measurements reached zero for the glowing dinoflagellate, Pyrodinium bahamense var. bahamense, at the end of September.^[5][6] Researchers have not found the cause of the current outage and are investigating extreme drought, a sargassum influx and other factors.^[7][8] DRNA has formally opened an investigation into the blackout.^[9] The bay generates million-dollar tourism revenue for Vieques, and Mayor Jose Corcino Acevedo is worried about the economic impact if the glow does not return.^[10][11] The bay is considered the brightest bioluminescent bay in the world, and authorities have cited a sargassum influx, El Niño-driven weather and tidal fluctuation as possible factors in the loss of glow.^[12][13] The Vieques Conservation and Historical Trust's counts now find no sargassum remaining in the bay, and non-bioluminescent plankton species are still present.^[14][15]