Possibly good news for coral reefs.

[studiot]

https://www.bbc.co.uk/news/business-66656369

 

Robots are trained to help revive coral reefs

 

[Genady]

The 2-halfday "Coral restoration" course for divers is very popular here for several years already. The baby corals are planted manually by happy divers and subsequently happily grow. It is inexpensive and fun.

These corals will be killed eventually by the climate change just like others.

[mistermack]

1 hour ago, Genady said:

These corals will be killed eventually by the climate change just like others.

It's not as total as people make out. Different corals like different conditions. And the way they reproduce means that their larvae drift for hundreds of miles. So if a location becomes unsuitable for one species, there's every chance that another will like it, and the species that died out in that spot will find another that has just become suitable. So the overall picture will be one of migration of species. What will suffer more than others is the fauna that inhabit the very coldest places. If they can't cope with warmer conditions, there's nowhere for them to go. 

[Genady]

Yes. This is exactly what will happen. In some virtual reality.

[TheVat]

There is also assisted migration (using artificial reef foundations like dropping terra cotta tiles on the bottom) toward a little deeper water where there is more protection from heat.  My impression is that this shorter migration might allow some coral species more generational time to adapt to warming and then slowly work their way back towards the original reefs.  

Some countries don't span enough degrees latitude to develop N/S migration, so the deeper water approach might help.

Edited September 12, 2023 by TheVat

[Genady]

21 minutes ago, TheVat said:

There is also assisted migration (using artificial reef foundations like dropping terra cotta tiles on the bottom) toward a little deeper water where there is more protection from heat.  My impression is that this shorter migration might allow some coral species more generational time to adapt to warming and then slowly work their way back towards the original reefs.  

Some countries don't span enough degrees latitude to develop N/S migration, so the deeper water approach might help.

1. There are crucial differences in light and water movement with depth which are disadvantageous for shallow water corals.

2. As soon as original coral population dies, the surfaces become covered with algae which prevents settling of new coral larvae.

Edited September 12, 2023 by Genady

[mistermack]

1 hour ago, Genady said:

2. As soon as original coral population dies, the surfaces become covered with algae which prevents settling of new coral larvae.

Have you got a link for that? It's at odds from what I've read. For example : Coral reefs ‘can recover quickly after bleaching’ - Asia & Pacific (scidev.net) 

 

This is an interesting angle. Apparently sunscreen is killing coral too. I would never have imagined that  :   Tropics told to ban coral-killing sunscreen - Asia & Pacific (scidev.net)   

[Genady]

13 minutes ago, mistermack said:

Have you got a link for that? It's at odds from what I've read. For example : Coral reefs ‘can recover quickly after bleaching’ - Asia & Pacific (scidev.net) 

 

This is an interesting angle. Apparently sunscreen is killing coral too. I would never have imagined that  :   Tropics told to ban coral-killing sunscreen - Asia & Pacific (scidev.net)   

It is not at odds with what you've read. Bleached coral is not dead. It is just the same living coral but without the symbiotic algae in it. The coral itself is like miniature jelly. It is colorless. The colors are those of the symbiotic algae. The coral without the symbiotic algae is alive for a couple of months. Bleached. Then it starts dying. Corals expel the algae naturally, when the water gets warm, and get the algae back when the water temperature goes down. It is when the water temperature stays warm for too long, which happens recently with the climate change, the bleaching becomes bad for corals.

The sunscreen effect, very old news. The signs here remind divers and snorkelers not to use sunscreen - or use special kinds only - for at least 10 years now.

[mistermack]

No link then. And, I'm well aware that coral can bleach for a short period without dying. But the page I linked was clearly not talking about a bleaching event of a few months : 

"Two years after the Chagos Archipelago bleaching event in 2015-2016, researchers found the reefs shrinking, with coral cover and carbonate production down by more than 70 per cent. But on returning in 2021, the researchers found the reefs on a path to recovery, though the speed varied from place to place, says a paper published 24 March in Limnology and Oceanography."

Coral larvae free-float for hundreds of miles, and find a place to anchor. That IS how they reproduce. If "the surfaces become covered with algae which prevents settling of new coral larvae." then they wouldn't successfully reproduce at all.  

 

 

[Genady]

26 minutes ago, mistermack said:

No link then. And, I'm well aware that coral can bleach for a short period without dying. But the page I linked was clearly not talking about a bleaching event of a few months : 

"Two years after the Chagos Archipelago bleaching event in 2015-2016, researchers found the reefs shrinking, with coral cover and carbonate production down by more than 70 per cent. But on returning in 2021, the researchers found the reefs on a path to recovery, though the speed varied from place to place, says a paper published 24 March in Limnology and Oceanography."

Coral larvae free-float for hundreds of miles, and find a place to anchor. That IS how they reproduce. If "the surfaces become covered with algae which prevents settling of new coral larvae." then they wouldn't successfully reproduce at all.  

 

 

Yes, it can recover. The process I've pointed to is real, but even the areas covered with macroalgae can become available again, for example if there is a healthy population of herbivorous animals. Here is one of the recent studies on this interplay: Macroalgal cover on coral reefs: Spatial and environmental predictors, and decadal trends in the Great Barrier Reef | PLOS ONE. They have found that,

Quote

Evidence of space competition between macroalgal cover and hard coral cover was restricted to shallow inshore sites. Temporally, macroalgal cover on inshore and mid-shelf reefs showed some fluctuations, but unlike hard corals they showed no systematic trends.

My knowledge of these processes is supported by 25 years of direct and close observations of the corals in the Bonaire Marine Park. But also limited to it.

[Genady]

An artificial selection for corals is going on in the Bonaire Marine Park:

Quote

After identifying colonies which have exhibited ‘resistance’ to the disease thus far, we are scheduled to begin propagating them by the end of this month. Furthermore, during the May spawning event of grooved brain coral (Diploria labyrinthiformis), another highly susceptible species, we reared hundreds of thousands of coral larvae in our floating ‘CRIB’ and successfully outplanted more than 25,000 young settlers onto the reef. Each of these settlers possesses a unique genetic makeup, equipping them with enhanced resilience to ongoing diseases and other stressors.

Coral Disease Is Causing Changes To Restoration Strategy In Bonaire - DeeperBlue.com

[Genady]

Another project to fight macroalgae in order to help corals:

Quote

Across the Caribbean and in Florida, scientists are pouring their time and resources into restoring reefs by planting (or “outplanting”) bits of coral on the seafloor. Yet without also ridding these ecosystems of algae, Spadaro said, restoration may struggle to succeed.

Quote

When a thick layer of seaweed covers the reef, it’s hard for baby corals — which spend their early days as larvae swimming in the ocean — to find a spot on the seafloor and start a colony. This seaweed not only takes up floor space but it can also limit the amount of sunlight that reaches the bottom (coral needs light to grow) and produce chemicals that dissuade corals from settling. Abundant algae also competes with adult colonies for space, crowding them out.

Quote

Algae is one of the few winners in a world dominated by humans. It thrives on our waste, such as sewage and runoff from farmland, which is full of nitrogen and phosphorous — nutrients that algae need to grow.

As pollution runs into the ocean, algae booms.

Meanwhile, animals that eat algae have declined precipitously in recent decades.

Quote

help is on the way. Scientists are in the process of building a crab army — hundreds of thousands of crustaceans strong — that they’ll unleash on Florida’s reefs, giving this ailing ecosystem a tool to fight back.

Quote

Making crabs even more appealing is that they’re native to Florida, just in relatively low numbers. (“Everything eats them,” Spadaro said.) Adding them to the reef is unlikely to have any grave unintended consequences for the ecosystem, Spadaro said, especially considering that there are few other herbivores.

Florida’s coral reef is in crisis. These crabs can help. - Vox

[studiot]

8 minutes ago, Genady said:

help is on the way. Scientists are in the process of building a crab army — hundreds of thousands of crustaceans strong — that they’ll unleash on Florida’s reefs, giving this ailing ecosystem a tool to fight back.

I hope so.

 

Thanks for the info +1