'Sea Snot' Has Invaded Turkey's Shores. Here's What Should Be Done To Fight It

An environmental disaster might be unfolding due to wastewater pressures, but engineers can help.
Derya Ozdemir
The photo credit line may appear like thisIstanbul Metropolitan Municipality

A potential environmental disaster is unfolding on the shores of Turkey as a thick layer of viscous fluid that has been spreading across the Marmara Sea for months has now started endangering marine ecology.

If you decided to take a walk across İstanbul's shoreline, the longest strip of land that views the Marmara Sea, a pungent smell and a nasty view of mucilage covering the once-blue sea would accompany you on every step.

The problem, which has been present for months now, can be seen on the surface off the coastlines of many other cities in the Marmara region, and it's also visible in deep waters, according to various reports by divers. Most recently, the sludge has also been spotted in the adjoining Black and Aegean seas.

All evidence suggests that the sea is experiencing the largest invasion of what is commonly known as 'sea snot' in its history.

When the problem first emerged in late December, it was only the fishermen that were affected since they couldn't cast their nets. Now, the situation has worsened, with reports of fish dying on the southern banks of Marmara popping up now and then.

Many residents on the coasts rely on fishing and tourism, so the sea snot is having a major impact. "Our work reduced up to 70 percent," one sea snail hunter told Daily Sabah.

But what is it and why the Marmara Sea?

The biggest evidence of the inadequate wastewater management in the Marmara region can now be seen by anyone who travels along its white-stricken shores. This substance is called marine mucilage, widely known as 'sea snot,' which is a collection of mucus-like organic matter found in the sea. 

Made up of dead and living organic material (much of it phytoplankton), it arises as a result of prolonged warm temperatures and calm weather in regions where the water has an abundance of nutrients.

When nutrients such as nitrogen and phosphorus are widely available in the seawater, the phytoplanktons are overloaded and grow out of control; and while they are necessary for a healthy sea, their abundance creates the opposite effect. The resulting mucus-like substance can span many square kilometers, blanketing the whole sea and endangering marine ecosystems.

The sea snot was first seen in the Marmara Sea in 2007, but it was never this bad. What's worse is, the problem doesn't end on the surface and has reached unprecedented levels, covering up to 80 to 100 feet (25 to 30 meters) below the water level and as far down as the seabed.

But why? The Marmara Sea has been struggling for the past decades as a result of the booming population, which has resulted in it receiving the wastewater of more than 20 million people as well as industrial wastes.

There are five metropolitan municipalities and two provincial municipalities surrounding it, and in these areas, municipalities treat their domestic wastewater by separating coarse and fine materials with screens and strainers. Then, these waters are get rid of through deep-sea discharge, which is a liquid waste disposal technology.

This technique tries to benefit from the dilution and natural purification processes of the sea: The wastewater is discharged to the seabed at certain distances from the coast using pipes and diffusers. However, studies done by many organizations have shown that the practice has led to the Marmara Sea being incredibly turbid, resulting in higher sea temperatures which in turn promoted marine mucilage, as explained by hydrobiologist Levent Artüz to Bir+Bir.

While there are decarbonization plants and advanced biological treatment plants, they are a minority.

These largely untreated waters are discharged to the seabed at depths of 130 feet (40 meters), and the technique has been used for many years since officials say the undercurrent going from the Mediterranean Sea to the Black Sea will enable the Marmara Sea to "breath" and clean itself. 

However, that hasn't been the case. The intense wastewater pressures due to domestic, industrial, and agricultural and animal husbandry activities have started to slowly kill the life beneath the waves. The wastewater is poured into the seas without any proper treatment, and many experts say only 10 percent of the fore-mentioned undercurrent reaches the Black Sea, and that this only happens under favorable conditions.

'Sea Snot' Has Invaded Turkey's Shores. Here's What Should Be Done To Fight It
The shores of Istanbul. Source: Istanbul Metropolitan Municipality

"We can't ignore the negative impact of deep-sea discharge," Prof. Yelda Aktan Turan from Istanbul University's Faculty of Aquatic Sciences told Interesting Engineering. She has previously studied another outbreak of marine mucilage in Marmara in 2007. "A certain proportion of the deep discharge causes an increase in the top layer nutrient load by returning to the upper layers, especially during certain periods."

There is also the problem of land reclamation, which is the process of creating new land from the sea, lakes, and others. There've been many instances of land reclamation on the coastal areas of the Marmara Sea to provide roads along the seaside and substitute the lost green areas, and according to a 2015 study, the reclaimed land on the Northern shoreline of the Marmara Sea reached 80 percent in 2014. 

It's known that inappropriate reclamation processes lead to a significant decrease in coastal ecosystems and species. And this also spells trouble, one that cannot be easily undone. 

"The destruction of productive coastal areas creates habitat loss and reduces biodiversity. Plants in these sloping and more light-receiving areas disappear, causing a further increase in phytoplankton," Aktan Turan explained. "This happens because phytoplankton species and plants in coastal areas compete for food. The plants reduce nutrients in the water by using the nitrogen and phosphorus load, but when they are gone, the competition disappears."

Global warming also worsens the issue since warmer, slower-moving waters increase the generation of sea snot. While the warming in neighboring seas is close to the world average of 1 degree, the temperature rise in the Marmara Sea is 2.5 degrees due to its turbid water attracting more heat.

Overall, though, the culprit is the untreated wastewater. "If we manage the main polluters properly, we can achieve a cleaner and healthier Marmara Sea," Prof. Mustafa Öztürk, who has studied both chemical engineering and environmental engineering, told Interesting Engineering. "Without eliminating the increased nitrogen and phosphorus elements, Marmara cannot get rid of its sea snot problem."

What is at stake?

The most obvious effect of mucilage is that it reduces visibility, thus limiting photosynthesis by preventing sunlight from reaching deep seas. "This leads to a lack of oxygen in deeper regions," stated Aktan Turan. "Oxygen concentration, which is already at critical numbers, ​further decreases with the collapse of the material to the bottom, and this poses a serious threat to all living things."

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The sea snot covers the gills of sea animals immersed in it, shuts off their oxygen supply, and suffocates them to death. It also affects reproduction since the vast majority of fish eggs are on the surface of the sea. These eggs, as well as the larvae, become trapped in the mucilage and have no chance of survival. 

Immobile organisms such as corals are particularly vulnerable since sea snot gets wrapped around them, impairing their ability to feed or breathe.

The mucilage traps zooplankton, covers the seagrass, and cuts off contact with light. This further reduces biodiversity, and given enough time, you end up with a dead sea.

What should be done?

This is something all scientists agree on: The waters have to be purified to reduce wastewater pressures, which is critical for lowering nutrient levels. So what should be done on an engineering level to fix this decades-old problem?

There are about 100 deep-sea discharge points in the Marmara region, Prof. Mustafa Öztürk says. "In order to minimize the excess nitrogen and phosphorus, Turkey needs to implement advanced purification technologies, and the Marmara Sea should be declared a sensitive area," he explains. "While some areas have already been declared sensitive in 2016, we know that, even in those areas, some municipalities don't treat the waters according to the expected limits."

This is especially important for gulf regions. Öztürk says that the wastewater in the gulf regions should be disinfected with UV rays and that it should be used as irrigation water in agricultural areas or in industry. 

"Inspections should be increased, and the wastewater should be brought to sensitive area levels everywhere. With urgent initiatives, treatment plants should be modernized," he urges.

Such projects can be carried out in a maximum of three months because they are based on well-known methodologies. According to Öztürk, they would add 5 to 10 percent to the cost of carbon removal facilities; however, "if the project is applied to plants based on separation, the conversion demands a large investment."

Some governors say waiting out the problem could solve the issue; however, unless a more direct approach is taken, the problem will surely resurface in the years to come, as the seas become hotter.

"If we can solve the wastewater problem and renew Marmara's water, it could be 10 times cleaner, healthier, and of higher quality in two years," Öztürk says.

What's being done?

Murat Kurum, Turkey's environment minister, stated that he intends to make the whole sea a protected area, minimize pollution, and enhance wastewater treatment, according to the Guardian. One of the plans seems to be reducing nitrogen levels by 40 percent, which could greatly help.

The ministry is now inspecting 91 different sites at the Marmara Sea, as well as all wastewater and solid waste facilities on land, with a team of 300 people.

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Kurum also invited locals and non-governmental organizations to participate in what he described as Turkey's largest ocean clean-up effort, which began on Tuesday. "We will take all the necessary steps within three years and realize the projects that will save not only the present but also the future together," he said, per Daily Sabah.

The Turkish president, Recep Tayyip Erdoğan, also commented on the issue, vowing to “clear our seas from the mucilage scourge." He warned that if the problem spreads to the Black Sea, it would become much worse, and told that officials must act quickly before it is too late.  

Due to climate change, our waters may only become hotter in the coming years. However, since Turkey can't reverse global warming on its own, ensuring wastewater is treated properly seems to be the only way out.

"June is especially important," Öztürk says. "That's because we generally see a decrease in pollution during the summer months. If that happens, the problem might seem like it was delayed for a while, but the projects need to continue in the meantime. The Marmara Sea is warning us, saying 'Invest now before it's too late.'"


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