Plants, Alga, and Plankton

strand of giant kelp floating near the surface of the ocean
Giant Kelp - Channel Islands National Park

NPS Photo

Marine plants and algae provide food and shelter to fish and other marine life, but they are not just important to aquatic ecosystems; they provide about 70 – 80 percent of the oxygen on Earth, making them extremely important in our everyday lives as well! Marine plants and algae are both different from and similar to their cousins on land: like terrestrial plants, they rely on sunlight, so they are only found at depths where light can penetrate. However, unlike terrestrial plant roots, the anchors that some aquatic plants, like kelp and sea grass, use to secure themselves to the sea floor don’t provide nutrients. Instead, these aquatic plants absorb nutrients directly from the water around them. Some also have air bladders that help them to stay afloat.

Despite the diverse array of aquatic habitats found in our coastal and Great Lake national parks, these special environments all rely on marine plants and algae. The carbohydrates these organisms produce fuel the entire marine food web, from the tiniest zooplankton to the largest whale.

Aquatic plants are sensitive to changes in water chemistry or temperature, so effects from pollution, ocean acidification, and climate change can wreak havoc throughout the ecosystem. Research and monitoring efforts help us better understand and protect these marine environments. From sea grass beds at Biscayne National Park to kelp forests at Glacier Bay National Park & Preserve, our coastal and Great Lake national parks are great places to explore and learn about the plant life that makes up such a critical part, not just of the marine world, but of our entire planet.

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