Seaweed Can Restore Ocean Dead Zones Caused By Nutrient Run Off

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In 2019, the “dead zones” in the Gulf of Mexico — areas with too little dissolved oxygen in the water to support aquatic life — totaled almost 7,000 square miles. “So what?” you may ask. The Gulf is 618,000 square miles in area. 7,000 is just a tiny percentage of the total. “Can’t those fish and shrimp and octopi just go swim somewhere else?”

It’s a fair point. The dead zones are just over 1% of the Gulf of Mexico. Can’t we just be happy with the other 98.8%? Let’s put it this way. New York City is a measly 302 square miles. Rhode Island is only 1,200 square miles. Connecticut spans 5,543 square miles. Saying “So what?” about the dead zones in the Gulf of Mexico is a little like saying all the people in NYC, Connecticut, and Rhode Island should simply move if the oxygen level in the air around them drops so low they can’t breathe.

Where do dead zones come from? Mostly from the deluge of nutrients that wash down the Mississippi River and other waterways into the Gulf from 32 states. Those nutrients feed huge algae blooms which actually create oxygen — for a while. But as quickly as the algae grows, it suddenly dies, sucking oxygen out of the water and leaving oxygen depleted dead zones behind.

And where do those nutrients come from? Some come from inadequate septic systems — such as those in and around Orlando, Florida — which wash untreated or partially treated sewage downstream to Lake Okeechobee and then onward through the Everglades to the Gulf. But much of it comes from the tens of millions of tons of fertilizer American farmers spread on their fields year after year.

Seaweed To The Rescue

Green shaded ares show where seaweed could be grown. Dashed line indicates low oxygen region of Gulf of Mexico. Image credit: Marine Policy/UCSB

Researchers at the University of California Santa Barbara say seaweed could help soak up lots of the nitrogen and phosphorous that runs downstream into the Gulf of Mexico. Seaweed also adds oxygen to the water. Writing in the journal Marine Policy, they say, “Seaweed aquaculture is capable of removing large quantities of nitrogen and phosphorus from coastal ecosystems, yet seaweed has gained little traction for its potential role in targeted nutrient assimilation. Marine nutrient pollution is increasing around the world, contributing to expanding eutrophic conditions and co-occurring with other stressors that impact the state and stability of aquatic ecosystems.”

According to The Fish Site (yes, that’s its real name), Darcy Bradley, co-director of UCSB’s Ocean and Fisheries Program and a co-author of the study, writes, “A key goal of conservation ecology is to understand and maintain the natural balance of ecosystems, because human activity tends to tip things out of balance. Dealing with nutrient pollution is difficult and expensive.” The US spends more than $27 billion annually on wastewater treatment.

Using open source oceanographic and human-use data, the researchers identified areas of the Gulf that are suitable for seaweed cultivation. About 9% of the United States’ exclusive economic zone in the Gulf could support seaweed aquaculture, particularly off the west coast of Florida — where the last algae bloom two years ago decimated that state’s tourist based economy.

“Cultivating seaweed in less than 1% of the US Gulf of Mexico could potentially reach the country’s pollution reduction goals that, for decades, have been difficult to achieve,” claims lead author Phoebe Racine, a PhD candidate at UCSB’s Bren School of Environmental Science & Management.

Cultivating seaweed could largely pay for itself. There are numerous cap and trade systems in place throughout the US designed to restrain the amount of nitrogen and phosphorous that runs into American waterways as well as other economic incentive programs designed to curb agricultural run-off. Seaweed aquaculture would fit nicely within these initiatives, Racine says. “Depending on farming costs and efficiency, seaweed aquaculture could be financed by water quality trading markets for anywhere between $2 and $70 per kilogram of nitrogen removed, which is within range of observed credit prices in existing markets.”

What’s more, the researchers note demand is rising for seaweed in food and industry sectors. Potential products include biofuel, fertilizer, and food. Feeding it to cows might lower their methane production. Unlike many pollution remediation strategies, seaweed aquaculture could actually pay for itself or even generate revenue.

“The US has traditionally had a lot of barriers to getting aquaculture in the ocean,” Bradley explains. “But there is mounting political support in the form of drafted bills and a signed executive order that could catalyze the expansion of the US aquaculture industry.”

The Takeaway

Humans are drowning in their own excrement. Whether it’s natural waste products, the carbon pollution that leads to warmer global temperatures, or contaminants in the water and soil around us from making things and growing things, our entire economic model is hopelessly flawed. We build and grow and expand with nary a thought for how to manage the effluent we create.

Have you noticed how the press is filled with reports about how we must zealously create systems for recycling lithium batteries but never mentions the horrors that surround our refineries and chemical factories? Have you seen any stories about the lethal sludge that accumulates at coal-fired generating facilities or the millions of gallons of toxic waste stored on industrial pig farms?

Of course batteries should be recycled but why are other enterprises excused from doing the same for their own waste products? Fair’s fair, people. We all need to think about whether we are willing to destroy the Earth that sustains us solely for our convenience.

The idea that seaweed could help alleviate nitrogen and phosphorus pollution is very good news. But why should we tolerate such massive pollution in the first place? When God gave us dominion over the Earth, did he tell us to go ahead and destroy it if we wish; He will simply make us a new planet in about 6 days? There’s no mention of that in any of the religious texts most of us are familiar with.

Seaweed and dead zones in the ocean are pieces of a larger whole. We can’t continue to thrive as a species if we insist on inundate our home with pollutants. We need to wake up from our long slumber as we slouch our way toward a self-made existential crisis.

The consequences of our profligate ways should be intuitively obvious to the most casual observers. That they are not is the scariest news of all. We are burying ourselves beneath our own muck and laughing about it. This isn’t going to end well.

Featured image courtesy NOAA

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Steve Hanley

Steve writes about the interface between technology and sustainability from his home in Florida or anywhere else The Force may lead him. He is proud to be "woke" and doesn't really give a damn why the glass broke. He believes passionately in what Socrates said 3000 years ago: "The secret to change is to focus all of your energy not on fighting the old but on building the new." You can follow him on Substack and LinkedIn but not on Fakebook or any social media platforms controlled by narcissistic yahoos.

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