To clarify: the green algae Ulva, aka "sea lettuce" (it is edible) is well established as a source of H2S. But "golden tides" of Sargassum may be competing with Ulva as the temperature rises, favoring the latter, which is known to be deadly.

https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2024.1464511/full

https://phys.org/news/2009-08-horse-dies-france-reality-toxic.html

The video mentions "toxic gases", without specifying what they are, which is unfortunate, perhaps dangerously so. H2S stinks horribly, so normally it's hard to get close enough to get a fatal dosage, but its high toxicity is often underappreciated. Prolonged exposure can "numb" the olfactory bulb so that the smell becomes more tolerable, increasing the risk of lethal exposure. It can penetrate neoprene diving suits, and be absorbed through the skin, as well.

Thanks

..... and the smell was awful.

I live in an affected area.

At its worst, it’s like living next to raw sewage.

On better days, it’s like living next to a horse stable.

Sargassum has been a problem for years but this year it’s particularly bad.

I’m glad that it’s getting some press.

It’s horrible and getting worse. Had to keep visiting family out of the water on the South Coast.