Impacts of dredging on Seagrass


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Impacts of dredging on Seagrass

  1. 1. Impacts Of Dredging On Sea grasses Mohammed Al Eid 0910659
  2. 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. 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. 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. 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. 6. Types Of Sea Grasses And Their Location Johnson’s grass star grass manatee grass widgeon grass shoal grass Turtle grass Paddle grass
  7. 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. 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. 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. 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. 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
  12. 12. Conclusion