Oil Spills, Ecology, and the Food Chain


While we become sick to our stomachs watching the spreading plumes of oil in the gulf, viewing photos of oil slicked birds, and footage of oil covered beaches in Florida and Alabama, let’s take a step back and think about the cycle of life. The reason disasters like this happen is due to a lack of understanding that, though we may be at the top of the food chain, we are not separate from it. Even though this is a lesson we were supposed to have learned in the first grade, we have separated ourselves from nature in an attempt to manage it and use its resources without a thought for how this impacts the entire system. The oil spill is a 12,000 mile wide, 50-million gallon proof point that we have been wrong.

The oceans are engines of life for the entire planet. Scientists believe that all life on earth began in the sea about four billion years ago. Our ancestors were the first tiny creatures that crawled onto the land. Today life depends on the ocean. Oceans are where life originated and hold the keys to our survival.

Half of the world’s oxygen is produced in the ocean. The BP oil spill is the largest in history. How far will it go? How much of the world’s oceans will it affect? All of this remains to be seen, but we do know that each tier of the marine food chain is affected by the oil spill. The only thing we don’t know yet is how widespread it will be.

Oiled birds and the closure of the fishery are dramatic and immediate effects of the spill, while vulnerable marshlands and the tiny creatures we cannot see are the engines of the entire ecosystem. According to this article in Nola.com – the online version of The Times Picayune – the thin layer of marsh mud is home to an entire valuable community of nutrients that feed the whole system. If the marsh is covered in oil, it will suffocate, and every creature that depends on it will suffer. According to the article, “half of the all the life created takes place in this slimy zone just seven-hundredths of an inch thick. It’s a world too small for the human eye to detect and involves creatures few people have ever heard of, but one that looms huge for the larger critters in the system.”

Here’s how it works: At the bottom of the chain are the phytoplankton. They live in the vulnerable marshes and near the surface of the water, obtaining their nutrients from organic matter in the marshes, sunlight, and water. In return they convert carbon dioxide to oxygen – oxygen that all of the rest of the food chain needs. In addition, phytoplankton provide direct nourishment to many sea creatures higher on the food chain. And some of those animals actually begin life in the marshlands, too. Shrimp mature in the marshlands, and then migrate to the ocean where they become food for fish. These fish provide nourishment to birds and animals, like us. It’s not hard to see what happens if the base of our food chain collapses. Where will the food for the other fish come from and how will we replace that oxygen?

According to this article in The Palm Beach Post, instead of the oil rising to the top where it can be easily tracked, the use of dispersants caused the oil to mix with the water and there are now giant plumes of oil traveling through the ocean. Nobody knows where they will end up or how much damage they will do to wildlife, but many scientists think that the oil is now more dangerous to filter feeders and larvae than if dispersants weren’t used. As one official with the U.S. Fish and Wildlife service was quoted as saying in the article, “This is just a giant experiment going on and we’re trying to understand scientifically what this means.”

Scientists are currently studying three different types of mollusks from the Gulf Coast to try to determine how long it takes for the toxic compounds in the water to work their way through the food chain. Because mollusks are constantly building their shells, they incorporate heavy metals and other toxins from the environment into their shells. An article from Science Daily details how scientists study growth rings in the shells of oysters, tellinid clams, and periwinkles. Each one of these mollusks feeds on different organisms at different levels in the sea, so scientists will be able to determine if the mollusks are acquiring contaminants from their food sources or the water directly by measuring the rate at which toxins accumulate in the shells.

As we all learned as children, the food chain begins with plants that get their energy through photosynthesis, which are then eaten by herbivores, and later consumed by carnivores. We eat and we are animals. Therefore, we are part of the food chain too. Just because we can drill wells, drive, and cook our food on a stove does not mean we are outside of this circle of life. We are as vulnerable as those oily birds. We just don’t feel it yet.

This is the latest installment in Vanessa Barrington’s weekly column, The Green Plate, on the environmental, social, and political issues related to what and how we eat.

Image: Kissyface

Vanessa Barrington

Vanessa Barrington is a San Francisco based writer and communications consultant specializing in environmental, social, and political issues in the food system.