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suncemoje

> Bleached corals are not dead

My open questions would be:

1. What's the consequence of corals expelling algae?

2. Why does heat make corals expel algae?

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1. The coral slowly starves to death. Like a tree without leaves 2. It's complicated but the algae essentially start damaging the coral in these conditions. Their photosynthesis mechanism runs into overdrive, generating too many electrons. With no way to consume this much power it dumps the energy into making reactive oxygen species which it ejects. These damage the coral (and the algae). The same thing occurs in plants - a fern growing on the forest floor can't handle full sunlight (photodynamic stress). Plants are less temperature sensitive though because they have active cooling (transpiration). But temperature and quantity of light both affect the photosynthesis machinery.

That makes me wonder - I’m sure it’s not a novel thought - if there is a more suitable species of algae for these conditions we can inject into bleached corals?

Impressive that corals have such a survival mechanism. But hopeless if no other species of algae can enter another symbiotic relationship with them?

> That makes me wonder - I’m sure it’s not a novel thought - if there is a more suitable species of algae for these conditions we can inject into bleached corals?

TLDR Yes but it's complicated. There are more suitable algae species but AFAIK coral under heat stress will still often expel the algae even if the algae isn't the one stressing the coral. So you have to essentially breed a more tolerant coral and then provide the algae.

Now luckily there do exist more heat tolerant coral and algae species living alongside each other. Unfortunately those species are located in the Persian Gulf/inside the Strait of Hormuz so they are regularly subject to added stressors from Oil/NG extraction, military conflicts, and waste dumping. And of course their location makes research on them/collaboration between research institutions complicated.

And it's not like you can just transplant these coral somewhere else and they'll live. They are adapted to their environment and that environment plays a part in their heat tolerance as well. But research on these coral ecosystems will likely shed a light on how to help other coral species to adapt and evolve.

> TLDR Yes but it's complicated. There are more suitable algae species but AFAIK coral under heat stress will still often expel the algae even if the algae isn't the one stressing the coral.

Maybe the pharmaceutical industry can target a new market here...

It's not just heat, it's ocean acidification. As the concentration of CO2 in the atmosphere increases, CO2 in the water increases as well. When CO2 dissolves into water, it forms carbonic acid. This is the same stuff that makes fizzy drinks like soda taste sour.

So more CO2 in air = more CO2 in the water = lower PH in the ocean. I don't know the details but the more acidic water messes with the chemical processes that corals and other aquatic life depend on.

The connection is that shells, such as the hard part of corals, are made from calcium carbonate. When you put calcium carbonate in acid, it dissolves. This takes some of the acid out of the water.

In the long run, there are huge deposits of calcium carbonate on the ocean floor. Even if we burn all of the fossil fuels, the ocean eventually comes back to a neutral ph.

The problem is the short run. We're turning CO2 into carbonic acid at a rate that far exceeds what surface waters can handle. This is creating conditions where shellfish of all kinds are working overtime form proper shells. If they can at all. It even affects many kinds of plankton. This stress is causing large dieoffs. When we wipe out things at the base of the food chain, it has ripple effects through the rest of the ecosystem.

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