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Seagrass Josie Strahle

Seagrass Josie Strahle. Grow in meadows Reproduce sexually and asexually Flower in summer emerged to 1.5m Originated on land and adapted to water High genetic diversity. Significance of Seagrasses. Provide nursery areas for juvenile fish and crustaceans

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Seagrass Josie Strahle

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  1. SeagrassJosie Strahle

  2. Grow in meadows • Reproduce sexually and asexually • Flower in summer • emerged to 1.5m • Originated on land and adapted to water • High genetic diversity

  3. Significance of Seagrasses • Provide nursery areas for juvenile fish and crustaceans • Provides food and habitat to endangered sea turtles and manatees • Also support mollusks, gastropods, insects, and other plants • High productivity, supports biodiversity • Export carbon, nitrogen, phosphorus to coastal food webs • Stabilize sediment on sea floor - improve water quality

  4. Seagrasses as Nurseries • Fish move to meadow as larva, move off shore when grown • Some studies report that growth is faster in seagrass beds than in non-vegetated environments • Importance varies geographically • meadows more important as nurseries in United States than in Australia • More important in tropical Caribbean then in Indo-Pacific region

  5. Usually Flat, linear leaves with parallel veins • Tallest - Thalassodendron ciliatum - 126 cm • Smallest - Halophilia minor - 2 cm

  6. Halophilia • Oval-shaped leaf

  7. Amphibolus • Ball formed by surf - Australia

  8. Zostera • Grows in intertidal

  9. Johnson’s seagrass - 1-2 inches tall • Can grow in very shallow water

  10. Physiology • Able to take up nutrient through roots and shoots • Fixed nutrients from detritus are then released by leaching and microbial mineralization • increases nutrient levels and energy flow in meadows

  11. Heterozostera • Woody underground root • grows close to shore

  12. Can tolerate range of salinity: above or below normal sea water • flourishes at salinity of 2, 12, 40% • 60% and above damaged plants • Epidermal cells exposed to high salinity show changes • mitochondria closer to plasma membrane • smaller vacuoles • complex wall in growths • density of mitochondria and choloroplasts increased • Smaller vacuoles

  13. Destruction of meadows • Because habitat is close to shore, seagrasses susceptible to destruction

  14. Loss of Meadows • National Marine Fisheries Service petitioned to list the seagrass as endangered in 1998 • Seagrass meadows being destroyed • Physical factors such as storms can destroy seagrass • Mostly human causes

  15. Dredging, anchor mooring, boat propellers • Erosion due to seawalls • Sedimentation, high salinity, poor water quality • Sewage discharge • Most significant seagrass killers are algae blooms

  16. Algae Blooms • Excessive nutrient inputs leads to algae blooms • waste water and farm run-off • Block out light • density of plants reduced • productivity reduced • light reduction can cause the collapse of a meadow in two years

  17. Once destroyed, meadows take decades to reestablish • Some cannot grow back because young plants need shelter of full grown plants

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