“In the next few decades, a lot of coral will die — that’s pretty much a given. And to be clear, this reality is absolutely devastating. Regardless of whether snorkeling is your thing, reefs are essential to human well-being: Coral reefs dampen waves that hit the shore, support commercial fisheries, and drive coastal tourism around the world. They’re also home to an incredible diversity of life that inspires wonder.”
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“But even as many corals die, reefs won’t exactly disappear. The 3D formation of a typical reef is made of hard corals that produce a skeleton-like structure. When the polyps die, they leave their skeletons behind. Animals that eat live coral, such as butterfly fish and certain marine snails, will likely vanish; plenty of other fish and crabs will stick around because they can hide among those skeletons. Algae will dominate on ailing reefs, as will “weedy” kinds of coral, like sea fans, that don’t typically build the reef’s structure.
Simply put, dead reefs aren’t so much lifeless as they are home to a new community of less sensitive (and often more common) species.”
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“On the timescale of decades, even much of the reef rubble will fade away, as there will be no (or few) live corals to build new skeletons and plenty of forces to erode the ones that remain. Remarkably, about 30 percent of the carbon dioxide that we pump into the atmosphere is absorbed by the oceans. When all that CO2 reacts with water, it makes the ocean more acidic, hastening the erosion of coral skeletons and other biological structures made of calcium carbonate.”
https://www.vox.com/climate/24137250/coral-reefs-bleaching-climate-change
“unseasonably hot water arrived this summer, meaning those coral colonies had to endure months of extreme water temperatures. A buoy off Florida recorded 101-degree water temperatures this July. When corals are stressed by hot or cold water, they lose their color—a result of expelling algae that provides corals with most of their energy—and eventually die.”
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“If the reefs collapsed completely, it would be disastrous for the Florida Keys. According to the Florida Fish and Wildlife Conservation Commission, the reefs in Southeast Florida are valued at $8.5 billion and sustain 70,000 full- and part-time jobs. The barrier reef also protects the Keys from hurricanes and major storms by soaking up wave action.”
https://reason.com/2023/12/19/the-florida-barrier-reefs-last-stand/
“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. In the 1980s, an unknown pathogen wiped out longspined sea urchins in the Caribbean. These marine invertebrates — which take the shape of an overfilled pin cushion — eat loads of algae. Similarly, overfishing and the loss of various ecosystems has caused declines in algae-eating fish, such as parrotfish.
Like a fertilized pasture with no cows, a field of algae on a reef with no herbivores grows unencumbered. In the last decade, the extent of algae on reefs globally increased by roughly 20 percent, turning them from brilliant fields of color to monochrome patches of green.
This is a serious problem for coral.
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.”
https://www.vox.com/down-to-earth/2023/9/27/23883039/florida-coral-reef-caribbean-king-crabs-restoration
“Coral in the Florida Keys, home to the largest reef in the continental US, is dying. The ghostly white appearance of the coral above is due to a phenomenon known as bleaching. Coral, an anemone-like marine animal, gets most of its color and food from a kind of algae that lives within its tissue. When that algae disappears, the coral appears stark white. Bleached corals aren’t dead; they are starving to death.
What happened between those two snapshots is extreme and unrelenting heat. Since July, a record-setting heat wave has been cooking waters in Florida and parts of the Caribbean, at times pushing water temperatures above 100 degrees. This excessive heat causes the relationship between coral and those symbiotic algae to break down; the algae leave the coral, though it’s not entirely clear which initiates the breakup.
The result of this epic marine heat wave is a devastating bleaching event that stretches across the Keys and much of the Caribbean, threatening the future of the region’s coral reefs. That in turn threatens human lives and well-being. These ecosystems — which were already under siege well before this summer — protect coastal communities from storm surge, support fisheries, and drive tourism.”
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“Underwater photojournalist Jennifer Adler and I went scuba-diving in the Florida Keys before and after this marine heat wave. What we saw is a stark reminder that climate change is not a distant threat; it’s destroying ecosystems today.”
https://www.vox.com/climate/23879347/florida-keys-coral-reef-photos-climate-change
“Even just a small difference in a reef’s height can make a big difference in risk, according to a study published last year in the journal Nature. Flood risk is often measured by what’s called the 100-year-flood zone — an area in which the chance of a flood in a given year is 1 percent. If coral reefs in the US lose 1 meter of height, that zone in the US would grow by 104 square kilometers (or about 26,000 acres), putting about 51,000 more people at risk of flooding, the study found.
That’s a big reason why losing reefs is so frightening. “These losses could escalate flood risk in just years to levels not anticipated by sea-level rise for decades or a century,” the authors of the Nature study wrote.”
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“Ultimately, protecting and restoring coral reefs is about much more than protecting coastal cities. Though they cover less than 1 percent of the world’s oceans, reefs sustain about one-quarter of all marine life and half of all federally managed fisheries. It’s hard to think of a better example of how helping an ecosystem is also helping ourselves.”