An investigation by the Department of Environment, Food and Rural Affairs said the most likely cause of the 2021 die-off was a naturally-occurring algal bloom.

Source: https://www.bbc.co.uk/news/uk-england-york-north-yorkshire-64265551?at_medium=RSS&at_campaign=KARANGA

Back before the first sea urchin die-off, Levitan recalled seeing reefs in the U.S. Virgin Islands blanketed in the spiny creatures.

Source: https://www.gjsentinel.com/news/us/mystery-solved-scientists-id-caribbean-sea-urchin-killer/article_e5c5f527-2a1d-5d34-9731-f1de1fdfab84.html

Biologists have previously blamed a giant seagrass die-off for causing starvation among the threatened species, mostly along Florida’s east coast.

Source: https://1010wcsi.com/fox-news/zoo-tampa-concerned-about-manatee-death-toll-its-very-disturbing/?utm_source=rss&utm_medium=rss&utm_campaign=zoo-tampa-concerned-about-manatee-death-toll-its-very-disturbing

Following the largest fish die-off in U.S. history, the tribes launched a decadeslong fight to remove the dams, a nearly complete effort that is poised to restore the lower Klamath River back to "the creator's country."

Source: https://phys.org/news/2023-06-opinion-massive-klamath-salmon-west.html

The official report details how dredging and pyridine were very unlikely to have caused the tragic die-off.

Source: https://www.chroniclelive.co.uk/news/cost-of-living/argos-portable-heater-money-heating-26024556

Those tipping points are the melting of the Greenland and Antarctic ice sheets, the mass die-off of warm-water coral reefs, the thawing of Arctic permafrost, and the collapse of the North Atlantic Subpolar Gyre circulation.

Source: http://redgreenandblue.org/2023/12/10/verge-five-climate-tipping-points-business-usual/