Protecting Marine Ecosystems

Protecting Marine Ecosystems

Learn about the types and goals of marine protected areas.


6 - 12+


Biology, Ecology, Earth Science, Oceanography, U.S. History

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How do oceans affect you? If you live far from the coast, you might think they don’t. But life on this planet depends on the ocean. Its cover almost three-quarters of the planet and hold 97 percent of Earth’s water. The phytoplankton that live on the oceans’ surface produce half of the oxygen in the atmosphere. Oceans are a vital source of food and other resources and an economic engine for many communities.

For all the ocean provides us, we haven’t always been so responsible in our stewardship. “The ocean was thought of as a dumping ground for so long,” says Caitlyn Toropova of the International Union for Conservation of Nature (IUCN). “There was a sense that there was no way we could harm it because it is so vast.”

But human activities are having a negative impact on many of the world’s oceans, jeopardizing marine life, habitats, and ecosystems. These threats include overfishing or destructive fishing, coastal development, pollution and runoff, and the introduction of non-native species. Climate change is also having a big effect by causing warming seas and ocean acidification.

The realization that something needs to be done to stem or reverse the damage has led to the creation of marine protected areas (MPAs). Broadly speaking, a marine protected area (MPA) is a region of the ocean where human activity is limited. Specifics differ around the globe, but the United States defines a marine protected area as “any area of the marine environment that has been reserved by federal, state, tribal, territorial, or local laws or regulations to provide lasting protection for part or all of the natural and cultural resources therein.”

There are approximately 5,000 designated MPAs around the world but many more that are not officially recognized, says Toropova, the conservation group’s coordination officer for marine protected areas. The United States has 1,700 MPAs.

That may sound like a lot, but less than one percent of the world’s oceans is protected. Countries around the world have committed to protecting 10 percent, Toropova says. But “even though there’s been an increase in the past 10 years, at the current rate it would take 100 years to reach that goal,” she says.

MPA Goals

While all MPAs are designed to limit human activity, there are different types of marine protected areas with different goals.

The U.S. National Oceanic and Atmospheric Administration (NOAA) developed a system that relies on a site’s five functional characteristics: conservation focus, level of protection, permanence of protection, constancy of protection, and ecological scale of protection.

A site’s conservation focus and its level of protection are the most important characteristics. A conservation focus asks what an MPA was created to protect. It could be the water’s natural heritage—such as its biodiversity, habitat, population, or ecosystems—or its cultural heritage, which reflects the country’s maritime history and connections to the sea. Or it might have been created for sustainable production, where the focus is on managing the removal of living resources such as plants, fish, or shellfish.

A level of protection determines what kinds of activities are prohibited, restricted, or allowed in a marine protected area. Here are the varying levels of protection MPAs provide, according to NOAA’s framework:

  • Uniform multiple-use MPAs allow activities, including fishing or taking other living resources from the water, across the entire protected area.
  • Zoned multiple-use MPAs allow people to take resources but limits where or when they can do so to lessen the impact on the area.
  • Zoned multiple-use MPAs with no-take zones are MPAs that allow many activities but have at least one zone where people are prohibited from taking any marine resources.
  • No-take MPAs or zones restrict people from taking any natural or cultural resources.

Types of MPAs

There are different types of marine protected areas. They may differ in their conservation focus and level of protection.

Marine reserves are usually no-take MPAs, and therefore prohibit any taking of resources. Activities that aren’t allowed include fishing and mining. Other activities, such as swimming and boating, are often permitted. Many reserves have a strong education or research focus.

Natural Bridges State Marine Reserve in California is one example. Located on the edge of the city of Santa Cruz, it covers 1.5 square kilometers (0.58 miles). Natural Bridges was created to protect surfgrass and sandy beach, which provide habitat for a variety of species. Fishing, drilling, and mining are not allowed at the MPA. Recreational activities like kayaking and swimming are allowed.

Marine sanctuaries have special conservation, recreational, ecological, historical, cultural, archaeological, scientific, educational, or aesthetic qualities. Most are multiple-use areas but may be zoned with no-take areas.

The Florida Keys National Marine Sanctuary is one of 13 U.S. sanctuaries. Located on the southern tip of Florida, it holds a wealth of natural resources, including the largest living coral reef in North America. The marine sanctuary is vast, covering 9,500 square kilometers (3,667 square miles). The rich variety of habitats includes seagrass beds and mangrove swamps. Thousands of species live in the Keys, sponges, jellies, anemones, mussels, oysters, and coral among them.

The sanctuary also holds cultural resources that offer a glimpse of the area’s maritime history. Since the European arrival to Florida in the 1500s, many ships have sunk in the waters off Florida. Artifacts from these shipwrecks rest in the sanctuary.

With its natural and cultural resources, it’s not surprising the Florida Keys draws visitors: more than 4 million people each year. Commercial fishing is vital to the economy of the Keys, where more than 20 million pounds of seafood are caught annually, according to NOAA.

The Florida Keys National Marine Sanctuary is a multiple-use MPA, with commercial, sport, and recreational fishing allowed in some zones. In other zones, only scientific research is allowed. Most of the park encourages a wide variety of recreational activities.

National parks are large areas preserved in their natural state as public property. They are designed to protect the natural and cultural objects and wildlife within the park.

Glacier Bay National Park and Preserve in Alaska, which covers more than 13,200 square kilometers (5,100 square miles), includes tidewater glaciers, snow-capped mountain ranges, ocean coastlines, deep fjords, and freshwater rivers and lakes. The conservation focus is on the arctic ecosystem. Commercial and recreational fishing are allowed but limited. Sport fishermen seek Pacific halibut and different species of salmon, such as sockeye, king, and coho, in Glacier Bay. Recreational activities such as kayaking, rafting, and boat tours are allowed.

Wildlife refuges conserve, protect, and enhance fish and wildlife and their habitats for the continuing benefit of people.

Breton National Wildlife Refuge, in the Gulf of Mexico off Louisiana, covers about 52 square kilometers (20 square miles) and is only accessible by boat. The focus of protection is its ecosystem. One goal is to provide a haven for nearly two dozen species of birds, from nesting and wading seabirds to waterfowl and wintering shorebirds. They include endangered species like the piping plover, the least tern, and the brown pelican.

The refuge suffered serious damage when Hurricane Katrina struck in 2005, and much of the land eroded.

Breton National Wildlife Refuge allows recreational fishing, but commercial fishing is prohibited. Wildlife viewing is a popular recreational activity, but because so much land was lost during Katrina, camping is no longer permitted.


Stakeholders are individuals, communities, or organizations with an interest in the marine protected area. As the above examples show, different types of MPAs provide different opportunities for stakeholders.

The general public uses MPAs for recreation such as fishing, kayaking, sailing, boat tours, snorkeling, or wildlife viewing. There are usually few regulations on recreational activities.

Commercial fishermen rely on the waters and the marine life in them for their livelihood. Most MPAs try to strike a balance between protecting resources and allowing for the sustainable extraction of those resources. As a result, there are very few no-take areas that prohibit all extraction. Many MPAs, however, do limit commercial fishing by where or when it can be done. Different seafood, such as salmon or lobster, have different seasons when it is safe and legal to harvest them.

Scientists and researchers use marine protected areas to study marine life and habitats. MPAs are "living laboratories" for scientists and researchers, where they can monitor and measure the health of species, ecosystems, and human impact.

As Toropova of the IUCN says, “Everything we depend on in life comes from the ocean.”

Fast Fact

Papahanaumokuakea Marine National Monument
Papahanaumokuakea, the area surrounding the remote and uninhabited Northwestern Hawaiian Islands, is the largest marine protected area (MPA) in the United States. The MPA is 362,072 square kilometers (139,797 square miles). Like most MPAs, it is multiple-use. The area's tuna and lobster fisheries remain open to seasonal use, while the remote islands provide protected areas for endangered species like the Hawaiian monk seal.

Media Credits

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National Geographic Society
Mary Crooks, National Geographic Society
Carol Johnson
Jeannie Evers, Emdash Editing, Emdash Editing
Kara West
Last Updated

January 9, 2024

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