2. Contents
What Is Sea Grass?
Where Is Sea Grass In The World?
Where Does Sea Grass Grow?
Types Of Sea Grasses And Their Location
What Are The Threats To Seagrass
Dredging
The Uses Of Dredging
The Impact Of Dredging On Environmentally And On Sea
Grass.
Conclusion
3. What Is Sea Grass?
Flowering plants adapted to
marine habitats.
Ribbon-shaped leaves
The only true flowering plants
that can live completely
underwater.
Provide food and habitat for
many creatures such as
juvenile sea turtles,
manatees, crabs, shrimp, and
a variety of juvenile fishes.
4. Where Is Sea Grass In The World?
Seagrass beds cover less than 10% of the world's shallow coastal waters, but are
important nursing grounds for commercial fish species
Greatest diversity: Indo-Pacific region
Located along the coast of all continents except Antarctica
5. Where Does Sea Grass Grow?
Must be fully submerged
Require saltwater to grow
Thrive in warm temperatures:
20-30 C
Require light for photosynthesis
Grow in shallow, coastal waters
Root system needs a stable softbottom habitat
6. Types Of Sea Grasses And Their Location
Johnson’s grass
star grass
manatee grass
widgeon grass
shoal grass
Turtle grass
Paddle grass
7. Location of Sea Grass Types
Turtle- Florida, Caribbean, Bermuda, area between Gulf of Mexico
and Venezuela
Manatee- Florida, Bermuda, Bahamas, Gulf of Mexico, Caribbean
Shoal- North Carolina, along the Atlantic, coast of Gulf of Mexico,
Caribbean
Johnson’s- Indian River Lagoon
Paddle- near Indian River Lagoon, Gulf of Mexico, Caribbean, IndoWest Pacific
Star- Florida, Bahamas, Texas, West Indies
Widgeon- Atlantic coast (New Found land-Texas)
8. What Are The Threats To Seagrass
Various human activities threaten the health of sea grass
ecosystems:
1.
Pollution from agricultural and industrial sources.
2.
Disposal of mining wastes.
3.
Overfishing—disruption of ecological interactions.
4.
Sediment movement from boat propellers.
5.
Dredging of harbors, ports And shipping lanes.
9. Dredging
Dredging is an excavation activity or operation usually carried out in
shallow seas or fresh water areas with the purpose of gathering up
bottom sediments and disposing of them at a different location. This
technique is often used to keep waterways navigable. It is also used
as a way to replenish sand on some public beaches, is also used as
a To establish and maintain navigation channels and harbors of
sufficient size to accommodate shipping vessels.
10. The Uses Of Dredging
Capital: dredging carried out to create a new harbor, berth or
waterway, or to deepen existing facilities in order to allow larger
ships access
Construction - the removal of materials previously undisturbed to
facilitate new navigation channels or water projects, e.g., locks and
dams.
Maintenance - The periodic and repetitive removal of accumulated
sediment from navigation channels and harbors to maintain
authorized depths and widths
11. The Impact Of Dredging On
Environmentally And On Sea Grass.
Reduction in water clarity both from increased turbidity and increased nutrient
loading.
Physical removal or burial of the vegetation and the indirect effect of increasing
sedimentation
Release of toxic chemicals (including heavy metals and PCB) from bottom
sediments into the water column.
Short term increases in turbidity, which can affect the amount of light penetrate
which affect aquatic species metabolism and interfere with spawning.
Dredging may affect the physical environment by changing the bathymetry,
altering current velocities and wave conditions
Disturbance of the substratum
Possible contamination of dredge spoils sites
Changes to the topography by the creation of "spoil islands" from the
accumulated spoil
Dredging could cause a Reduction of the dissolved oxygen
