Ocean waters cover more than 70% of the Earth’s surface. The oceans play a vital role in regulating temperature, and they provide food for animals and people alike. Yet the oceans face several major challenges in the 21st century, and one of the most dire of these problems is pollution.
We have all seen pictures of dolphins and sea turtles struggling with plastic or massive floating garbage patches. It is hard to say exactly how much garbage is in the ocean, but the National Oceanographic and Atmospheric Administration estimates that billions of pounds of trash and other pollutants get dumped into the ocean each year.
While it may seem that much of the garbage floating on the ocean’s surface can simply be picked up and removed, it is not that simple. These so-called garbage patches are constantly being moved around by wind and waves. The patches are also mostly made of microplastics — bits of tiny plastic debris that are difficult to grab. Even if we found a way to scoop up all that garbage, there may be nowhere to put it. Just one area, called the Great Pacific Garbage Patch, is more than a million square kilometers.
While marine debris is an issue, a large share of oceanic pollution comes from land-based sources like agricultural runoffs, pesticides, and untreated sewage. Corporations certainly contribute to direct and indirect ocean pollution and higher surface temperature — these are 20 corporations that have some of the largest impact on the oceans in their industries. A large share of chemical runoff, however, comes from farms.
This nutrient pollution can create “dead zones” in a number of ways, including by stimulating the growth of algae. When it decomposes, algae consumes oxygen and can deplete the supply to the point that marine life is unable to live in that area. Fish can swim away from these areas, but slower or stationary marine life such as coral reefs are typically killed if their habitat becomes a dead zone.
Algae can also be harmful while it is living. While algae provide most of the oxygen we breathe, excessive growth known as algae blooms — which are often caused when nutrients from farms and other sources overfeed algae and make it grow faster than usual — can produce toxic compounds that devastate coastal and freshwater regions as they contaminate seafood and drinking water with toxins. These blooms can make shellfish poisonous, choke out ecosystems, and even make beaches unsafe for people to visit.
Dr. Quay Dortch, program manager of Ecology and Oceanography of Harmful Algal Blooms Program at NOAA explained how polluting nutrients can cause algae blooms and affect ecosystems for extended periods.
“They get into algae, the algae gets eaten, and eventually the organisms that eat them die and re-excrete some of the nutrients. But some of it falls out and gets into bottom sediments. And from the sediments, some of it is recycled,” Dortch said.
While many well meaning scientists and philanthropists are doing their best to save our oceans, there may not be many good options for cleansing the waters of chemicals and other pollutants. Dortch noted that there are some options for cleaning phosphorus out of freshwater systems, but they have not yet proven to be cost-effective solutions. It seems that, at least presently, the only way to effectively get pollution out of the ocean is to stop it from getting there in the first place, and hope that the damage already done is not irreversible.