Submerged Aquatic Submerged Aquatic VegetationVegetation

WWHAT HAT IIS S IIT AND T AND WWHY HY IIS S IIT T IIMPORTANT?MPORTANT?

Image provided by Ronald C. Phillips

What Is Submerged Aquatic Vegetation (SAV)?

• SAV consists of plants that spend their life cycle completely submerged– Includes algae, but usually

refers to complex plants such as seagrasses

• SAV does not include marsh grasses

Image provided by NOAA Department of Commerce

Image provided by Ronald C. Phillips

Seagrasses

Image provided by Alexandre Meinesz, University of Nice-Sophia Antipolis

Algae

Marsh grasses

What Are Seagrasses?

• Type of SAV• Exhibit seasonal growth• Contribute to a rich, productive

ecosystem• Provide oxygen, food and habitat for

many animals

Paige Gill - Florida Keys NMS

Where Do Seagrasses Grow?

• They require habitats where sunlight can reach the bottom

• They typically prefer shallow clear water

• They grow close to the shore in many coastal regions

• They occur from the Tropics to the Arctic Image provided by Ronald C. Phillips

• They release oxygen into the water• They provide habitat and shelter• They are a food resource• They help stabilize the shoreline• They help maintain water quality

Why Should We Care about Seagrasses?

Seagrasses Release Oxygen into the Water

• Seagrasses use sunlight to produce oxygen

• Many economically important fish and shellfish require oxygen

Image provided by Fred Short

Seagrasses Provide Habitat and Shelter• Leaves provide habitat for tiny

plants• These tiny plants are the food

resource of many economically important finfish, shellfish, and crustaceans.

• Leaves provide hiding spots for juvenile finfish and other animals

• Roots and stems prevent efficient foraging by predators who dig for prey

Image provided by SFWMD

Image provided by Heather Dine

Seagrasses Are a Food Resource

• Seagrasses are a primary food source for manatees and sea turtles

• Many migratory waterfowl such as the Canada Goose and Black Brant consume seagrass

Image provided by Ronald C. Phillips

Seagrasses Help Stabilize the Shoreline

• Roots trap sediments• Seagrasses buffer the shore from storm

effects• They help prevent erosion

Seagrasses Help Maintain Water Quality

• Roots trap sediments and promote water clarity

• They reduce sediment stirring caused by currents

• Stems and roots hold dead materials in place for

decomposition

Images provided by Ronald C. Phillips

Why Are Seagrasses Threatened?

• Seagrasses grow close to the shore and coastal areas are naturally dynamic

• Seagrases grow in areas that typically have increased development and recreational pressures

• There are laws that protect seagrasses, but it is hard to protect what you can’t see

Natural Threats to Seagrasses

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• Overgrazing can decimate seagrass beds

• Storms can uproot or bury seagrasses

• Drought can change water levels, which can expose seagrasses

• Changes in rainfall can alter salinity, which can stress or kill seagrasses

• Outbreaks of diseases can cause diebacks

Human Threats to Seagrasses• Fertilizer and other chemical

runoff reduce water quality• Reckless boating can

contribute to prop scars • Docks shade seagrass beds• Dredging destroys habitat • Sediment runoff buries

seagrasses and clouds water• Certain shellfish harvesting

methods destroy seagrass beds

Harold Hudson - NMS Florida Keys

Can SAV Be Harmful?

• Some SAV can cause problems • These plants can grow quickly and

crowd out seagrasses• They often thrive in polluted waters• Their quick growth may lead to

large population sizes • They may contribute to fish and

shellfish die-offs• Plants clog waterways and choke

boat engines

Image provided by Kawartha Fisheries Association

Image provided by SFWMD

Why Should We Protect Seagrasses?

• Seagrasses supports a healthy coastal environment

• They are important in maintaining recreational and commercial fisheries

• They are legally protected• Seagrasses help reduce

erosion

How Do We Know Where Seagrasses Live?

• Field monitoring– Underwater surveys– Underwater photographs

and videography• Remote sensing

technology– Aerial imagery– Underwater sensors

How Can You Help?• Always use pump-out stations to dispose of boat waste • Avoid vegetated shallows when planning dredging or

pier construction • Participate in water quality monitoring programs• Practice responsible boating and navigation

• Help environmental organizations plant seagrasses• Use environmentally friendly landscaping techniques