Habitats | Ecosystem Disturbance

May 9, 2024

Blue tang (Acanthurus coeruleus) swimming through coral, Puerto Rico, La Parguera, January 2005 (by NOAA CCMA Biogeography Team, courtesy of NOAA Photo Library, CC BY 2.0 DEED via Flickr).

A Healthy Coral Reef Is a Symphony – Reasons to be Cheerful Magazine

Excerpt:
In the growing field of “ecoacoustics,” scientists use the ocean’s natural sounds to monitor the health of marine ecosystems — and even restore them.

You might have heard that the Great Barrier Reef is the world’s largest collection of coral reefs, a natural wonder stretching over 1,400 miles off Australia’s Queensland coast, hosting 400 types of coral and thousands of fish species. Since 1981, it has been recognized as a UNESCO World Heritage Site, and most of its ecosystem is protected.

But you might not know that it is also the stage for daily underwater concerts. Take a dive or listen to marine biologist Steven Simpson’s recordings and you hear grunt fish grunt, shrimps snap, damselfish chirp, clownfish grumble, sperm whales click and humpback whales sing their soprano mating songs that are audible over tens of miles.

“When I tell them fish have ears, people look at me like I’m mad,” says University of Bristol professor Steve Simpson. He and his colleagues were initially ridiculed by their peers when they started eavesdropping on fish communication nearly 20 years ago, but their sound experiments have been recreated successfully so many times that they are established science now. Recent research has revealed that dolphins call each other by name, turtle embryos coordinate their birth with one another from inside their eggs, and a coral reef is also a symphony that attracts coral larvae. Much like doctors use stethoscopes to assess the healthy heartbeat of a patient, the interdisciplinary science of ecoacoustics, which investigates natural sounds and their relationship with the environment, has emerged as an effective solution not only for monitoring the health of marine ecosystems, but also for restoring them.

The world has lost half its coral reefs in the last 30 years, and researchers are racing against the clock to support these invaluable habitats in their battle against warming waters, pollution, overfishing and acidity. “Scientists predict that, if we continue along the current global warming trajectory, coral reefs will entirely disappear from the oceans within 30 years, threatening the livelihoods of the more than one billion people who depend on them for food, medicine, and coastal protection,“ the late University of British Columbia professor Karen Bakker writes in her fascinating book The Sounds of Life. “The disappearance of corals is a death knell for many other species.” 

As the coral reefs disappear, so too does their chorus. “When a reef diminishes, the diversity and complexity of the sound goes missing, too,” Simpson says. “It becomes an acoustic desert. You can really hear the difference between an overfished reef and a marine protected area. You can hear the biodiversity…”

BBC Earth Unplugged (04-06-18):
Fish Sounds: Do fish talk to each other?

Excerpt:
Did you know fish chirp, crackle and whoop?! Hear why fish make these surprising sounds as Professor Steve Simpson reveals how technology is uncovering a hidden world of communication on our coral reefs.

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More on Habitat | Ecosystem Disturbance

One Tree Island, Great Barrier Reef: the majority of corals have died and among the few survivors, many are now bleached. In the foreground are two small bleached Galaxea colonies and an unbleached Montipora - May 1, 2024 (by John Turnbull CC BY-NC-SA 2.0 DEED via Flickr).

Great Barrier Reef’s worst bleaching leaves giant coral graveyard: ‘It looks as if it has been carpet bombed’ – the Guardian

Last month the Australian Institute of Marine Science and the Great Barrier Reef Marine Park Authority released a report warning that the reef was experiencing “the highest levels of thermal stress on record”. The authority’s chief scientist, Dr Roger Beeden, spoke of extensive and uniform bleaching across the southern reefs, which had dodged the worst of much of the previous four mass bleaching events to blight the Great Barrier Reef since 2016…

Bleached plate corals and Sea Fans on Molasses Reef, Key Largo, Florida (by Matt Kieffer CC BY-SA 2.0 DEED via Flickr).

Corals are bleaching in every corner of the ocean, threatening its web of life – the Washington Post

First around Fiji, then the Florida Keys, then Australia’s Great Barrier Reef, and now in the Indian Ocean. In the past year, anomalous ocean temperatures have left a trail of devastation for the world’s corals, bleaching entire reefs and threatening widespread coral mortality — and now, scientists with the National Oceanic and Atmospheric Administration and International Coral Reef Initiative say the world is experiencing its fourth global bleaching event, the second in the last decade…

Bleached corals at low tide, Heron Island, Australia, April 10, 2024 (by John Turnbull CC BY-NC-SA 2.0 DEED via Flickr).

The Widest-Ever Global Coral Crisis Will Hit Within Weeks, Scientists Say – the New York Times

The world’s coral reefs are in the throes of a global bleaching event caused by extraordinary ocean temperatures…It is the fourth such global event on record and is expected to affect more reefs than any other. Bleaching occurs when corals become so stressed that they lose the symbiotic algae they need to survive. Bleached corals can recover, but if the water surrounding them is too hot for too long, they die…

Staghorn Coral (Acropora cervicornis) in Bonaire, Caribbean Neatherlands, taken on January 21, 2024 (by Tom Murray CC BY-NC 2.0 DEED via Flickr).

Six Months After the Heat Spiked, Caribbean Corals Are Still Reeling – Hakai Magazine

For many Caribbean corals, last year’s heat proved too much to bear. The more time corals spend in hot water, the more likely they are to bleach, turning white as they expel the single-celled algae that live within their tissues. Without these symbiotic algae—and the energy they provide through photosynthesis—bleached corals starve. Survival becomes a struggle, and what had been a healthy thicket of colorful coral can turn into a tangle of skeletons…

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