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Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Wetlands of the Pacific Southwest

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Vegetated Shallows

Seagrass growing in shallow waters

Seagrass grows in shallow waters of the tropical Pacific

Vegetated shallows are areas that are submerged most or all of the time and support rooted aquatic plants. They can occur at depths with sufficient light penetration in fresh, estuarine and marine waters. These areas provide critical spawning, rearing, and foraging habitat for a wide range of fish and invertebrate species. They are also important in concentrating and recycling nutrients and helping to stabilize shorelines from erosion.

Throughout California and the Pacific Islands, respectively, beds of eelgrass and turtlegrass (flowering aquatic plants visible in shallow waters or at low tide in many estuarine and marine locations) are perhaps the most easily recognized type of vegetated shallows. Since vegetated shallows generally require clear, clean water to thrive, they are at risk from a variety of human activities that tend to increase suspension of sediments into the water or reduce visibility. These include, for example, uncontrolled runoff from adjacent lands and dredging and other modification of shallow water areas for navigation purposes. Direct destruction, non-native invasive species, oil spills, and other pollutants can also cause significant impacts.

Because of their importance and sensitivity, vegetated shallows are protected under the Clean Water Act as “special aquatic sites.”

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