Patterns that led to collapse of wildlife populations on land now occurring in oceans

University of Santa Barbara researchers reviewed the past, present and future of marine animal life in a new study titled „Marine defaunation: Animal loss in the global ocean". Consortium of scientists,  found that the same patterns that led to the collapse of wildlife populations on land are now occurring in the sea. 

Current trends in ocean exploitation suggest that habitat destruction is likely to become mayor threat to ocean wildlife in the 21st century. As the footprint of ocean use increases, low rates of extinction observed today could just be a prelude to an extinction pulse, similar to land animal extinction during the industrial revolution.

Human activity has profoundly decreased the abundance of both large and small marine fauna. Such declines can generate waves of ecological change that travel both up and down marine food chains and can alter ocean ecosystem functioning. Human harvesters have also been a major force of evolutionary change in the oceans and have reshaped the genetic structure of marine animal populations.

Marine defaunation: Animal loss in the global ocean. Video credit: UCSB

“All signs indicate that we may be initiating a marine industrial revolution,” said Douglas J. McCauley, an ecologist at the University of California, Santa Barbara, and a lead author of the new research, which was published on January 16, 2015 in the journal Science. “We are setting ourselves up in the oceans to replay the process of wildlife Armageddon that we engineered on land."

The new paper compares the march of the Industrial Revolution on land to current patterns of human use of the world’s oceans. During the 1800s vast tracts of farmland and factories beat back forests and sucked up resources that were mined and drilled out of the ground. As a result, many terrestrial species were driven to extinction. In the ocean, however, fishing continued to rely on sailing ships clustered in small slivers of near-shore water. 

“There are factory farms in the sea and cattle-ranch-style feed lots for tuna, shrimp farms are eating up mangroves with an appetite akin to that of terrestrial farming, which consumed native prairies and forest. Stakes for seafloor mining claims are being pursued with gold-rush-like fervor, and 300-ton ocean mining machines and 750-foot fishing boats are now rolling off the assembly line to do this work," said co-author Steve Palumbi of Stanford University, underlining several new threats.

According to the authors, increasing industrial use of the oceans and the globalization of ocean exploitation threaten to damage the health of marine wildlife populations, making the situation in the oceans as grim as that on land. As McCauley pointed out, we now fish with helicopters, satellite-guided super trawlers and long lines that can stretch from New York to Philadelphia.

“All signs indicate that we may be initiating a marine industrial revolution,” he said. 

One solution the paper highlighted involves setting aside more and larger areas of the ocean that are safe from industrial development and fishing. However, another co-author Robert Warner, an EEMB research professor at UCSB, cautioned that reserves alone are not enough. “We need creative and effective policy to manage damage inflicted upon ocean wildlife in the vast spaces between marine protected areas,” he said.

Among the most serious threats to ocean wildlife is climate change, which according to the scientists is degrading marine wildlife habitats and has a greater impact on these animals than it does on terrestrial fauna. “Anyone that has ever kept a fish tank knows that if you crank up your aquarium heater and dump acid into the water, your fish are in trouble,” said co-author Malin Pinsky, an ecologist at Rutgers University. “This is what climate change is doing now to the oceans.”

Still, as the researchers emphasized, the relative health of the oceans presents an opportunity for saving them. “Because there have been so many fewer extinctions in the oceans, we still have the raw ingredients needed for recovery,” said McCauley. “There is hope for marine species that simply does not exist for the hundreds of terrestrial wildlife species that have already crossed the extinction threshold.”

The ocean’s future is yet to be determined, the researchers said. “We can blunder forward and make the same mistakes in the sea that we made on land, or we can collectively chart a different and better future for our oceans,” Warner concluded.

Source and featured image: UCSB

Reference:

• "Marine defaunation: Animal loss in the global ocean" – Douglas J. McCauley, Malin L. Pinsky, Stephen R. Palumbi, James A. Estes, Francis H. Joyce, Robert R. Warner – Science January 16, 2015: Vol. 347 no. 6219 –  DOI: 10.1126/science.1255641