Transcript Submerged Aquatic Vegetation What it is and why it is important

Submerged Aquatic
Vegetation
WHAT IS IT AND WHY IS IT IMPORTANT?
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
Algae
Image provided by Alexandre Meinesz,
University of Nice-Sophia Antipolis
Seagrasses
Image provided by Ronald C. Phillips
Marsh
grasses
Image provided by NOAA Department of Commerce
What Are Seagrasses?
Paige Gill - Florida Keys NMS
• Type of SAV
• Exhibit seasonal growth
• Contribute to a rich, productive
ecosystem
• Provide oxygen, food and habitat for
many animals
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
Why Should We Care about
Seagrasses?
•
•
•
•
•
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
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
Image provided by SFWMD
Image provided by Heather Dine
• 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
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
• 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
Image provided by SFWMD
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