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Averting a mass extinction

July 19, 2024 By EarthWise Leave a Comment

Averting a sixth mass extinction

There has been widespread concern that biodiversity is under siege and that we are in the beginnings of a sixth mass extinction in the long history of the Earth, this time caused by the actions of humanity.  There has been considerable debate about what can be done about it and solutions generally involve protecting large areas of the planet from human disruptions.  Some countries have set a target of protecting 30% of land and sea.

A new study by a broad coalition of conservation organizations and published in Frontiers in Science, concludes that humans can preserve much of the great diversity of life on Earth by setting aside just 1.2% of the planet for protection.

The experts mapped the wilderness available to rare and threatened plants and animals.  They then identified specific hotspots for rare wildlife that have yet to be protected.  They found a total of 16,825 such sites which nevertheless all together add up an area smaller than the state of Wisconsin.

Some scientists have been warning that by focusing too much on the size of protected lands, we are not necessarily safeguarding areas that are especially rich in wildlife.  The new study pushes for prioritizing hotspots for rare species, which the authors claim would be sufficient to stave off a sixth mass extinction.  The truth is that most species on Earth are rare, meaning that they are few in number or cover a small range, or both.

The study estimated that the cost of protecting the identified hotspot sites would be $263 billion, which is certainly a large amount of money.  But the authors point out that this sum to save global biodiversity is less than the yearly revenue of Shell Oil.

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To Avert a Mass Extinction, Protect 1 Percent of Earth

Photo, posted April 20, 2018, courtesy of Per Harald Olsen / AfricanBioServices via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Caribbean Coral Reefs Under Siege | Earth Wise

January 4, 2021 By EarthWise Leave a Comment

Coral reefs face myriad of dangers

Coral reefs around the world have been suffering from warming seas and increasing acidification, both a result of human activity.  In the Caribbean, a new threat has emerged in the form of invasive algae.

New research published in Scientific Reports explains how an aggressive, crust-like alga is overgrowing shallow reefs and taking the place of coral that was damaged by powerful storms that exposed areas of the undersea rock where corals grew. 

Researchers from Oxford University, the Carnegie Institution, and California State University Northridge have been studying these peyssonnelid algal crusts, or PACs, for several years in the U.S. Virgin Islands.  The PAC has been out-competing coral larvae for surface space and then growing over the existing reef architecture, greatly damaging delicate reef ecosystems.

New corals actually prefer to settle on crusty surfaces created by a different type of algae called crustose algae, or CCA.  CCA acts as guideposts for coral larvae by producing biochemical signals as part of a microbial community that entice baby coral to affix itself.

In contrast, the destructive PAC algae exclude coral settlement. The researchers determined that the microbial community associated with PAC algae is deployed to deter grazing from fish and other marine creatures.  Unfortunately, it also deters coral.

Fragile coral ecosystems are already under assault by environmental pollution and global warming.  Now, in the aftermath of powerful hurricanes like Irma and Maria, algal crusts are taking over reef communities and posing an existential threat to Caribbean corals.

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An unusual microbiome characterises a spatially-aggressive crustose alga rapidly overgrowing shallow Caribbean reefs

Photo, posted January 11, 2015, courtesy of Falco Ermert via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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