Glowing Seas & Giant Jellies Endanger Commercial Fisheries

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Glowing Seas & Giant Jellies Endanger Commercial Fisheries

Sjonnie van der Kist/Flickr

Saleh al-Mashari is the captain of a marine research vessel in the Gulf of Oman. Last month, he gazed out in dismay over a patch of stinking green flotsam the size of Mexico.

Two weeks later—and 7,000 miles away—beachgoers in Tasmania witnessed another unsettling event.

Shortly after dark, a luminescent tide lapped up against the island’s northwest coast. Like something out of science fiction, the eerie blue light caught the eye of photographer Leanne Marshall—along with throngs of enthusiastic YouTubers.

The link between these two bizarre events? The Irish call it Sea Ghost, the Taiwanese Blue Tears. But for scientists like professor Gustaaf Hallegraeff of the University of Tasmania the culprit is known as Noctiluca Scintillans.

Noctiluca is a dinoflagellate, a single-celled marine plankton that produces bioluminescent flashes to scare off predators. Once a relatively rare sight, the plankton is becoming increasingly common in nutrient rich coastal waters.

"We have some evidence that ocean currents and the warming of the oceans have contributed to it — it's definitely a species that is showing a spectacular range expansion in the last 20 years," Hallegraeff tells the Australian Broadcasting Corp.

Unfortunately, Noctiluca’s otherworldly light show can spell disaster for marine ecosystems. "This is an organism that eats other species” Hallegraeff explains. “[So] if there's a huge amount of it…it behaves like a vacuum cleaner and it eats away all the other plankton.”

When blooms of Noctiluca eradicate keystone plankton populations, more complex marine organisms—as well as the human populations who depend on them—can be in serious trouble.

"We have heard, for example, on the east coast [of Tasmania] complaints from shellfish farmers that after this Noctilucal bloom went through, suddenly the shellfish were hungry because there was nothing left to eat," Hallegraeff says.

Similar accounts surfaced back in Oman, where blooms of Noctiluca large enough to be seen from space are absorbing oxygen at an alarming rate—creating massive marine dead zones in the process.

"The fish are migrating, they can't get enough air here [,]" says captain al-Mashari.

Behind the Bloom

While naturally occurring changes in seasonal climate and ocean currents can explain some Noctiluca blooms, the massive scale and increased frequency of recent bloom events point to man-made causes.

Researchers at Greenpeace cite increased levels of nitrogen and phosphorous from agricultural run-off as a major cause of the recent blooms. These agricultural pollutants form warm, nutrient rich or ‘eutrophic’ waters—the perfect hunting grounds for swarms of Noctiluca.

While nutrient rich fertilizers and other agricultural pollutants certainly play a large role in creating algal blooms, experts point to untreated human sewage as the single largest source of eutrophication in the developing world.

Whether from fertilizer or sewage, overloading a marine environment with nitrogen and phosphorous has devastating effects. The added nutrients spur the growth of droves of organisms, a veritable banquet for plankton like Noctiluca. After consuming all the available food, the Noctiluca begin to decay, a process that sucks up oxygen from the surrounding water.

When large numbers of Noctiluca die off, they create massive anaerobic dead zones like the one observed by al-Mashari in the Gulf of Oman. Unfortunately, oceanic dead zones can now be found in at least 405 locations around the world.

Only a few creatures can survive these dead zones. Even fewer actually thrive.

Each summer, tons of fertilizer flows into the Gulf of Mexico, producing a dead zone of nearly 10,000 square miles. As with dead zones in the Yellow Sea and China’s Pearl Delta, some of the few creatures that survive in the gulf’s oxygen-starved waters are jellyfish.

Without any predators, the jellyfish are left to grow to huge sizes and in astonishing numbers. In recent years, virtual invasions of giant jellyfish— called Nomura blooms—have plagued Japan, destroyed an organic salmon farm in Ireland and wrecked sardine and anchovy fisheries off the coast of Namibia.

With glowing waves of Noctiluca Scintillans starving coastal waters of oxygen and decimating commercial fisheries—albeit with the help of giant gelatinous invaders—something must be done to protect our seas.

Saving the Seas

The best solutions for preserving biodiversity and local livelihoods from Noctiluca focus on prevention. This means going after the agricultural and environmental pollutants that cause the blooms in the first place.

Unfortunately, environmental pollutants like nitrogen and phosphorous almost always stem from a variety of sources rather than a single point of origin. This makes managing them more complicated than simply monitoring a single factory or field.

Instead, solutions need to be more systemic, taking local environmental, economic, and social conditions into account. Luckily, plenty of organizations are doing just that.

One example is the International Maize and Wheat Improvement Center based in Mexico. The center is a non-profit research and training institution that helps small-scale farmers around the world adopt sustainable farming practices. It has played an instrumental role in popularizing a practice called no-till farming.

No-till farming, sometimes called zero-till, is said to increase crop yields while dramatically reducing agricultural runoff. Of course, less nutrient-rich runoff in coastal waters means less Noctiluca, a win-win for both farmers and fisherman.

While plenty of organizations pitch no-till farming, the center sets itself apart by tailoring its programs to the specific environmental, economic, and social conditions of its partners.

The organization has pioneered successful zero-till planters in Pakistan, introduced resource-conserving tech and drought-resistant seeds in India, and promoted conservation agriculture in Malawi.

But reducing agricultural runoff isn’t the only way to protect our seas. In fact, for much of the developing world, untreated sewage presents the largest threat to coastal waters.

Even though technologies exist that can remove 95 percent of phosphorous and 90 percent of nitrogen from sewage, they’re often far too costly for developing nations to install and maintain.

The Bill & Melinda Gates Foundation is working to change that.

In 2011, the foundation launched the Reinvent the Toilet Challenge. The challenge invites contributors from around the world to submit sustainable sanitation proposals that focus on affordability.

By improving access to toilets and encouraging sanitary waste disposal, the program protects coastal watersheds from contamination by unprocessed human waste.

Since 2011, the Reinvent the Toilet Challenge has received dozens of ingenious submissions. Proposals have covered everything from solar powered waterless toilets to community outreach campaigns discouraging open defecation in urban slums.

The cumulative impact of the Gates foundation’s challenge may be difficult to measure, but there’s every reason to remain optimistic. The challenge has spurred on innovations in biotechnology which turn algae itself into a key ally in the fight against harmful Noctiluca blooms.

A growing number of companies like the Israeli startup Aquanos are cashing in on this innovation, using microalgae to cut down the cost of removing nitrogen and phosphorous from human sewage.

With any luck, algae based sewage treatment systems may finally turn the tide on Noctiluca Scintillans.

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