Threats to the Ocean: Human Impact & Solutions

Instructor: Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

In this lesson we'll be learning about how humans are harming our oceans through pollution, global warming and over fishing. But, don't despair! We'll also examine solutions to these problems to help preserve our oceans for generations to come.

What Threatens Our Oceans?

Picture setting sail on a cruise in the Pacific Ocean. Off to see beautiful, tropical islands, you're excited to start your vacation. But, as you look down into the water, it's not the turquoise paradise you had imagined. In the Pacific Ocean, millions of pieces of microplastics, tiny pieces of plastic from discarded trash, float in the water. These plastic pieces, along with larger pieces of plastic and other trash make up garbage patches that drift between the coast of California and Japan. Garbage patches not only pollute the ocean but also kill sea birds, seals and other marine life. Today, we're going to look at this and other threats to our oceans, and then we will also look at some solutions.

Threats

Unfortunately, garbage is only one threat to our oceans. Today, we're going to look at three common threats to oceans: pollution, global warming, and fishing.

Pollution

Plastic

Plastic is especially harmful to ocean life because it doesn't degrade readily like paper products do. Plastics can take hundreds of years to decompose, allowing them to drift around our oceans without decay. Plastic products look like food to sea life below. Sea animals that mistakenly consume the plastic can't digest it, causing clogs in their digestive system and eventually death. Other times, air-breathing animals, like sea turtles, get caught in plastic products and can't reach the surface, causing them to drown.

Oil Spills

Plastics aren't the only way humans are polluting our oceans. Oil spills have disastrous affects on marine life and the coasts nearby. In 2010, one of the largest oil spills in the history of the United States occurred in the Gulf of Mexico. Over 3 million barrels of oil poured into the ocean after an explosion on the Deepwater Horizon oilrig. The oil not only polluted the ocean waters and the coral reefs beneath it, but also destroyed delicate estuary ecosystems on shore.

Coral in the 2010 oil spill
coral

Global Warming

Although we might think of atmospheric pollution as a separate problem, the toxic pollutants we release into our air also affect our oceans. Carbon dioxide is a major contributor to global warming, an increase in global temperatures. Global warming is causing the melting of polar ice caps and warming of our oceans.

Although the change in ocean temperature may be small, the consequences can be disastrous to some of our most productive ecosystems. Coral reefs are home to the greatest marine biodiversity on Earth. These ecosystems are extremely delicate, and even slight changes in temperature can cause coral to die in a process called coral bleaching. When coral dies, the animals and plants it supports also die. The Great Barrier Reef in Australia is currently undergoing a mass bleaching event that started in 2014, one of the worst bleaching events in history.

Bleached coral in the foreground versus healthy coral
coral bleaching

Fishing

With the growing awareness of the health problems associated with eating red meat, many people are turning to the ocean for their next meal. However, like industrial agriculture, fishing poses many threats to our ecosystems. Fisheries are collapsing world wide, with over 70% of our fisheries being fully exploited to completely collapsed. The overfishing of large predators like tuna, sea bass, and grouper removes keystone species that regulate the population of other fish in the area, leading to population crashes.

But, it isn't just the species we actively catch that are in danger. Bycatch is any species caught during fishing that aren't intended for sale. In 2005, the NOAA (National Oceanic and Atmospheric Administration) estimated that 17% of fish catches in the United States were discarded as bycatch. Bycatch kills marine mammals, sharks, sea turtles and other important species needed to keep our marine ecosystems in balance.

Rays caught as bycatch in a Virginia fishery
bycatch

Solutions

The situation might be looking pretty grim at this point, but there are ways we can help protect our oceans.

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