As technology improves and humans delve into the unknown depths of the ocean, marine life is increasingly in danger of harm and even extinction, according to a report released by a team of scientists earlier this month.
For their article, “Marine defaunation: Animal loss in the global ocean,” published in Science, researchers looked at hundreds of sources of data about humanity’s impact on the ocean, from habitat loss to climate change.
They concluded that marine life is on the brink of suffering the same doomed fate as many land animals, said Malin Pinksy, an author of the article.
“It’s easy to think of the ocean as incredibly vast, but that is increasingly no longer true,” said Pinsky, an assistant professor at the Institute of Marine and Coastal Sciences.
He likened human development in the ocean, such as deep-water mining, to a “marine Industrial Revolution” similar to the Industrial Revolution on land that began in the 19th century.
In that time, animal populations on land began to decline, like marine populations are doing today.
But although the detrimental effects of human intervention are accelerating, he stressed that most species and most habitats are doing well.
“It’s not too late,” he said.
He cited seabed mining, destruction of wetlands, overfishing and others as direct actions of humans that have changed the marine ecosystem.
But some of the biggest issues came from smaller and more indirect problems, such as habitat loss. Oceans have lost 40 percent of coral cover and 20 percent of mangroves, both of which help to shelter fish populations, he said.
“Habitat loss is tricky,” he said. “It’s made of 1,000 small actions that act like many small cuts, and then you bleed to death.”
Part of the difficulty of habitat loss is that it is difficult to recreate lost habitats, he said. Many of them have been formed over “10,000 years” of geological history and are difficult to recreate.
Another wide-reaching problem for marine life is climate change, an issue with implications on the entire ocean, he said.
“It’s like if you had an aquarium, and you cranked up the heat and dumped in acid,” he said.
Global temperatures have risen one degree Celsius in the past century, while most marine species are adapted to a narrow range of temperatures. When their habitat’s temperature rises beyond what they can tolerate, some are forced to migrate hundreds of kilometers, which heavily affects local ecosystems.
This effect is not merely a prediction for the future, as scientists have already observed this occurring particularly with the black sea bass population. Pinsky said the fish species has moved from the coast of Virginia to the coast of New Jersey to adjust to temperature changes.
Climate change also affects the acidity of the ocean, as carbon dioxide, a major greenhouse gas, dissolves into ocean water. The acidity makes it harder for corals, sea urchins and mollusks to form shells, he said.
Anthony Broccoli, co-director of the Rutgers Climate Institute, said the report did not surprise him, but the study was unique for being more comprehensive than others in the past.
He said the problems with marine ecosystems were concentrated near the coast, where climate change might cause flooding in salt marshes and other coastal areas.
The change of habitat seen with marine organisms, like the black sea bass, is being mimicked on land, he said. For example, plants in mountainous areas have begun moving to higher altitudes toward cooler temperatures.
The impacts of climate change will be greater with further warming ahead, he said.
“The warmest years on record have all been in the last 15 years,” he said. “We know now there is a trend toward warmer temperatures.”
Olaf Jenson, assistant professor in the Department of Marine and Coastal Sciences, researches fisheries and aquatic ecosystems. He agreed ocean life has suffered devastating losses due to human interference.
He said two-thirds of the fish populations have been historically overfished. Developed nations have begun to fish sustainably, but that has pushed the problem into developing nations.
“It’s a challenge, because there’s a tremendous [demand] for fish ... from demand for seafood in the United States, China and so on,” he said.
He suggested that concerned students eat local seafood, because New Jersey fisheries tend to be carefully managed.
Pinsky said students should try using Seafood Watch, an app that shows whether certain seafood types are sustainable.
Broccoli said individual contributions are important, but wide-reaching action is essential for change.
“The most effective thing to do is to let our leaders know that we need to address these issues,” he said. “People see the effects of climate change as far into the future, so the issue may not demand the same focus, but changing the path we’re on requires action.”
The main objective is to gain a consensus among world leaders that this is an important issue, he said.
Pinsky said other, more immediate issues demand attention from the public, so environment issues tend to fall by the wayside.
“Yet, our long-term survival and quality of life depends on the ocean,” he said.