Seagrass lecture

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Seagrass lecture

  1. 1. Coastal communities: Seagrass beds <br />Dr. Loretta Roberson, UPR-RRP and Institute of Neurobiology<br />
  2. 2. OUTLINE<br />What is seagrass?<br />Associated flora and fauna<br />Seagrass ecosystem function<br />Habitat connectivity<br />Disturbances and threats<br />
  3. 3. What is seagrass?<br />
  4. 4. What is seagrass?<br />Leaf<br />Rhizome<br />Root<br />Sheath<br />
  5. 5. What is seagrass?<br />True flowering plant (angiosperms)<br />Monocots (lily, corn, rice)<br />Not a true grass<br />Wholly submerged in salt or brackish water<br />Can reproduce sexually and asexually<br />developed a submarine pollination mechanism<br />can produce large, old clones<br /> (600 m2 and >1,000 years old)<br />
  6. 6. What is seagrass?<br />Aerenchyma<br />specialized parenchyma with regularly arranged air spaces (gas exchange, buoyancy)<br />Chloroplasts in the leaf epidermis<br />Require high light levels<br />25% of incident radiation (compared to 1% in other plants)<br />supports large amount of nonphotosynthetic tissue<br />must provide oxygen to roots and rhizomes <br /> (toxic sulfide sediments)<br />
  7. 7. What is seagrass?<br />59 species worldwide in 12 genera<br />Abundant in Australia, Alaska, S. Europe, India, E. Africa, SE Asia, Caribbean, Gulf of Mexico<br />7 species found in Caribbean:<br />Thalassia, Syringodium, Halodule, Ruppia, Halophila engelmanni, H. decipiens, and H. baillonii<br />
  8. 8. What is seagrass?<br />7 species found in Caribbean:<br />Thalassia, Syringodium, Halodule, Ruppia, Halophilaengelmanni, H. decipiens, and H. baillonii<br />Thalassia<br />Syringodium<br />
  9. 9. World Seagrass Distribution<br />From: World Atlas of Seagrasses 2003<br />Coral distribution <br />
  10. 10. World Seagrass Distribution<br />Florida<br />Gulf of Alaska<br />
  11. 11. Factors affecting distribution <br />Physiology<br />Temperature<br />Salinity<br />Waves<br />Currents<br />Depth<br />Substrate <br />Day length<br />Photosynthesis<br />Light<br />Nutrients<br />Epiphytes<br />Disease <br />
  12. 12. General Habitat Characteristics<br />Shallow, soft bottom<br />Clear water<br />Protected from wave action<br />Monospecific or mixed stands<br />Patchy <br />
  13. 13. Associated flora and fauna<br />
  14. 14. Associated flora and fauna<br />Bacteria<br />Fungi<br />Diatoms<br />Algae (green, red, brown)<br />Protozoa (slime mold, forams)<br />Sponges<br />Cnidarians (corals)<br />Polychaetes<br />Ribbon worms<br />Sipunculid worms<br />Flatworms<br />Crustaceans (shrimp, lobster)<br />Bivalves (oysters, scallops)<br />Gastropods (Conus, Strombus)<br />Cephalopods (squid, cuttlefish)<br />Bryozoans<br />Echinoderms (sea cucumbers)<br />Tunicates<br />Fish (snapper, sea horses)<br />Reptiles (green turtles)<br />Birds (Brant geese)<br />Mammals (dugong, manatee)<br />
  15. 15. Functions of seagrass – An ecosystem perspective<br />Primary production<br />Canopy structure<br />Below-ground structure <br />Wave and current energy damping<br />Nutrient, contaminant and sediment filtration and trapping<br />Nutrient regeneration and recycling<br />Epiphyte and epifaunal substratum<br />
  16. 16. Primary production – Photosynthetic organisms<br />Cyanobacteria<br />Diatoms and Coccolithophores<br />Algae – includes zooxanthellae<br />Plants – seagrass <br />
  17. 17. Primary Production<br />·  primary production = rate of photosynthesis or chemosynthesis<br />·  utilize sunlight or chemical nutrients as a source of energy (autotrophy) <br />·  the lowest level of the food chain<br />Primary producers serve as the basis <br />for nearly all life in the ocean<br />
  18. 18. Factors Affecting Primary Productivity<br />Light<br />Nutrients<br />Hydrographicconditions<br />Currents<br />Upwelling<br />Vertical mixing<br />
  19. 19. Estimates of primary production<br />Pelagic zone = 50-600<br />Grasslands = 2,400<br />Tropical forests = 5,000<br />Mangroves = 2,700<br />Coral reefs = 1,200-8,000<br />Seagrass beds = 800-10,000<br /> (measured as g C/m2/yr )<br />
  20. 20. Ecosystem function – Canopy structure<br />
  21. 21. Ecosystem function – Canopy structure<br />
  22. 22. Ecosystem function – Below-ground structure<br />
  23. 23. Ecosystem function – Epiphyte and epifaunal substratum<br />
  24. 24. Ecosystem function – Epiphyte and epifaunal substratum<br />
  25. 25. Ecosystem function – Epiphyte and epifaunal substratum<br />
  26. 26. Ecosystem function – Wave and current energy damping<br />
  27. 27. Ecosystem function – Wave and current energy damping<br />
  28. 28. Ecosystem function – Nutrient, contaminant and sediment filtration and trapping<br />
  29. 29. Ecosystem function – Nutrient regeneration and recycling<br />
  30. 30. Habitat connectivity<br />
  31. 31. Habitat connectivity<br />N<br />
  32. 32. Habitat connectivity<br />
  33. 33. Habitat disturbances<br />Natural<br />Waves<br />Hurricanes<br />Animal foraging<br />Anthropogenic<br />Eutrophication<br />Sedimentation<br />Habitat destruction<br />Overfishing<br />
  34. 34. Natural disturbances – Waves<br />
  35. 35. Natural disturbances – Waves<br />
  36. 36. Natural disturbances – Hurricanes<br />
  37. 37. Blow outs<br />
  38. 38. Natural disturbances – Animal Foraging<br />
  39. 39. Natural disturbances – Animal Foraging<br />
  40. 40. Natural disturbances – Animal Foraging<br />
  41. 41. Natural disturbances – Animal Foraging<br />
  42. 42. Natural disturbances – Animal Foraging<br />
  43. 43. Anthropogenic disturbances – Eutrophication<br />The process by which a body of water becomes enriched in dissolved nutrients that stimulate the growth of aquatic plant life<br />
  44. 44.
  45. 45. Eutrophication – HABs <br />[ Harmful Algal Blooms ]<br />
  46. 46. Eutrophication – HABs <br />
  47. 47. Anthropogenic disturbances – Sedimentation<br />
  48. 48. Anthropogenic disturbances – Sedimentation<br />
  49. 49. Anthropogenic disturbances – Urbanization<br />
  50. 50. Anthropogenic disturbances – Urbanization<br />10 km<br />Shading = >1,000 persons/mi2<br />From: Planning Commission of Puerto Rico, Office of Land Use<br />
  51. 51. Other anthropogenic disturbances - <br />Propeller scarring<br />
  52. 52. Other anthropogenic disturbances - Harvesting<br />
  53. 53. Caulerpa<br />Ballast water<br />Other anthropogenic disturbances - Invasive species<br />
  54. 54. Anthropogenic disturbances – Overfishing<br />
  55. 55. Anthropogenic disturbances – Overfishing<br />Before Fishing<br />After Fishing<br />Jackson et al., Science 293, 629 -637 (2001) <br />
  56. 56. Jackson et al., Science 293, 629 -637 (2001) <br />>3.3 × 107 adult turtles historically  1.1 × 106 50-kg turtles today<br />
  57. 57. Current research<br />Orth et al. 2006 Bioscience 56(12): 987-996<br />More seagrass research!!<br />
  58. 58. Current research<br />Effects of water quality on seagrass community productivity and biodiversity in NE Puerto Rico<br />USGS Water Resources <br />Data 2004<br />
  59. 59. “Non-impacted” - 7S<br />Impacted - LC<br />Study sites – Fajardo<br />
  60. 60. Biodiversity - Fish<br />Impacted<br />“Non-Impacted”<br />
  61. 61. Biodiversity - Fish<br />*<br />* From Kopp et al. 2007 Aquatic Botany<br />
  62. 62. Conclusions:<br /><ul><li> Nearshore and watershed water quality are poor, </li></ul>mainly due to sediment not nutrients<br /><ul><li>More stable communities may protect biodiversity (and vice versa)
  63. 63. Higher frequency measurements are needed, especially light
  64. 64. Long-term studies are needed (study is ongoing) i.e., SeagrassNet.org
  65. 65. Seagrass conservation areas and nearshore water quality management are needed in Puerto Rico!</li></li></ul><li>

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