Most of the plastic pollution on coral reefs comes from this

By Alice Clifford via SWNS

Most plastic pollution on coral reefs comes from fishing, reveals new research.

Three-quarters of plastic items found across the Indian, Pacific, and Atlantic oceans were from fishing equipment such as ropes, nets and lines, according to the findings.

With 88 percent of the debris found being larger than two inches, the structural complexity of coral reefs has been damaged, causing a drop in the number and variety of fish.

Study co-author Dr. Lucy Woodall, an associate professor in marine conservation biology and policy at the University of Exeter, said: “Fishing gear, which even as debris continues to catch marine life through what we call ghost fishing, appears to contribute a large proportion of the plastic seen on mesophotic reefs.”

The team conducted more than 1,200 visual surveys across 84 coral reef ecosystems in 14 countries.

They found that the amount of plastic pollution also increased with depth. The most pollution was found on coral reefs in mesophotic zones.

These reefs sit in between well-lit shallow waters and the deepest parts of the ocean, often between 30 and 150 meters deep.

Scientists believe that the pollution has reached such depths thanks to increased wave action and turbulence near the surface which dislodges rubbish and carries it away.

Human-derived debris was found in nearly all locations studied.

It was even found in some of the planet’s most remote and pristine coral reefs, such as those next to uninhabited islands in the Central Pacific.

The least pollution was found in areas such as the Marshall Islands - a chain of volcanic islands and coral reefs in the Pacific Ocean. Here they found around 580 items per square kilometer.

Comoros, an island chain off the southeast coast of Africa, had the highest density of pollution with nearly 84,500 items per square kilometer.

This is equivalent to around 520 pieces of debris on one football field.

The depths these plastics go into is a cause for worry among scientists as they are more difficult to study.

To survey the hard-to-reach mesophotic they used specialized diving gear that few other scientific dive teams are trained to safely use.

Co-author Dr. Bart Shepherd, director of California Academy of Sciences Steinhart Aquarium and co-director of its Hope for Reefs Initiative, said: “Our findings provide more evidence that the mesophotic is not a refuge for shallow reef species in a changing climate as we once thought.

“These reefs face many of the same pressures from human society as shallow reefs, and have a unique and poorly-studied fauna.

“We need to protect deeper reefs and make sure that they are included in the conservation conversation.”

Senior author Dr. Luiz Rocha, the co-director of the Hope for Reefs Initiative, said: “It was surprising to find that debris increased with depth since deeper reefs, in general, are farther from sources of plastic pollution.

“We are almost always the first humans to set eyes on these deeper reefs, and yet we see human-produced trash on every dive.

“It really puts the effect we have had on the planet into perspective.”

While pollution on reefs increased with depth, it also rose with proximity to densely populated cities, local markets, and strangely marine protected areas.

Since most marine protected areas allow some fishing within or near their borders and are typically more productive than other locations due to their protected status, they are often heavily visited by fishers.

Study author Dr. Hudson Pinheiro, a biologist at the Center for Marine Biology of the University of São Paulo, said: “Our findings reveal some of the complex collective challenges we face when dealing with plastic pollution.

“As marine resources around the world dwindle, humans that rely on those resources are turning to deeper habitats and those closer to marine protected areas where fish remain abundant.”

According to the study, coral reefs appear to be more contaminated by plastics and other human-derived debris than other marine ecosystems.

However, they are much less polluted than shoreline ecosystems like beaches and wetlands.

Dr. Pinheiro added: “Plastic pollution is one of the most pressing problems plaguing ocean ecosystems, and coral reefs are no exception."

“From macroplastics that spread coral diseases to fishing lines that entangle and damage the structural complexity of the reef, decreasing both fish abundance and diversity, pollution negatively impacts the entire coral reef ecosystem.”

The team hopes that by finding the major drivers of pollution and showing that plastic pollution increases with depth, conservation efforts can be better redirected.

Study author Dr. Paris Stefanoudis, a marine biologist at the University of Oxford, said: “The results of our global study shine a light on one of the many threats that deep reefs face today.

“Because these ecosystems are ecologically and biologically unique, much like their shallow-water cousins, they need to be conserved and explicitly considered in management plans.”

Dr. Lucy Woodall added: “Unfortunately, fishing gear debris is often not reduced by general waste management interventions.

“Specific solutions related to the needs of fishers should be considered, such as no-charge disposing of damaged gear in ports or individually labeling gear to ensure fishers take responsibility for misplaced equipment.”

Scientists stress the need to expand the depth of marine protected areas to include mesophotic reefs.

They also suggest that international agreements on combatting plastic pollution should be updated to include fishing gear. With this, they hope to see the development of low-cost biodegradable alternatives to fishing gear.

Dr. Shepherd added: “Despite the disturbing overall trend, there were some places where we found relatively little debris, which shows us that there are effective strategies for preventing plastic pollution.

“If we act fast and employ science-based solutions, there absolutely is hope for coral reefs.”

The study was published in the journal Nature.