Unfortunately stony corals also face a grave threat from ocean acidification due to rising CO2 in the atmosphere. They need alkalinity to make their skeletons.

Probably not a reef-scale solution, but as triage for nurseries and high-value colonies during heatwaves, this seems genuinely useful

Couldn't you have a floating hole filled net to give shade over larger areas? I guess this is the early stages of testing the idea, but if it's promising enough, I think floating surfaces are the way to go.

- "Seeding steel frames brings destroyed coral reefs back to life" (2024) https://news.ycombinator.com/item?id=39735205#39735363 ... re: MARRS program Reef Stars (Hexagonal, three-foot-wide steel frames coated in a layer of coral sand and limestone) and:

> - "Playing sounds of healthy coral on reefs makes fish return" (2019) https://news.ycombinator.com/item?id=36450824#36465577 and other Coral Restoration links

Stopping direct sunlight exposure to help stop coral bleaching is an awesome idea.

Have to nitpick though, umbrellas protect you from falling water, parasols block light.

Looks like a feel good solution mostly. Good for donations, but is not so clear how much would solve the problem. The solution to environmental problems is never cheap so the best use of resources is to use money where it can assure that the problem will never happen. After if happens common people can't fix it. Is too expensive.

A problem is that corals need algae to photosinthesize so too much shadow is also bad.

Another is that the shadowed water will be still hot, because the cold water moves away with the tides and oceanic temperature inertia is too powerful. So now corals could have two problems instead one problem. Feel good solution.

A better focus would be to use some kind of system to move deep water up using the reef topology. Would be noisy and obtain permits will be a real pain in the ass, but at least could work for a while to protect entire ecosystems in small areas that can be used later to seed other areas around.

In the meanwhile as this is not easy, this small umbrellas are time consuming to build and can dislodge and hit other corals potentially breaking or damaging fragile species that need decades to grow, a floating and well anchored second hand jumping bed would be much more efficient, relatively less risky to crash against submerged corals, and a little more durable. Many owners of jumping beds with holes on it, would be glad to get rid of... donate them for free for a good cause. At least this is needed just in summer and will need to be removed before winter storms turns it into garbage. Small fishes will use also this platforms for refuge so corals could also benefit of that.

Watching the health of the colony constantly to see if there is too much shadow is essential, Also place it out of the fishermen way and never on ship routes. And this can't be used in areas with seals.

So how do you install 250k km2 of underwater umbrellas, and who stands to get filthy rich from this?

Yea

Nothing that could potentially scale without unintended consequences. Next

It’s all the ships from China spewing carbon into the ocean