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Life near the surface

Explore the three categories of marine life near the surface - Benthos, Nekton, and Plankton. Learn about the physical factors that affect plankton and the different types of phytoplankton and zooplankton. Discover the importance of plankton in the food chain and the role of krill in the Antarctic ecosystem.

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Life near the surface

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  1. Life near the surface

  2. Marine life 3 categories: • Benthos: bottom dwellers; sponges, crabs • Nekton: strong swimmers- whales, fish, squid • Plankton: animal/plants that drift in water. The have little control over their movement. • Includes: diatoms, dinoflagellates, larvae, jellyfish, bacteria.

  3. What physical factors are plankton subject to? • Waves • Tides • Currents

  4. Plankton classified by: • Size • Habitat • Taxonomy

  5. Size: • Picoplankton (.2-2 µm) bacterioplankton • Nanoplankton (2 - 20 µm) protozoans • Microplankton (20-200 µm) diatoms, eggs, larvae • Macroplankton (200-2,000 µm) some eggs, juvenile fish • Megaplankton (> 2,000 µm) includes jellyfish, ctenophores, Mola mola

  6. Plankton • Holoplankton Portuguese Man-O-War

  7. Plankton • Meroplankton

  8. Holoplankton or Meroplankton?

  9. Taxonomy Zooplankton Phytoplankton

  10. Phytoplankton- restricted to the euphotic zone where light is available for photosynthesis. • Blooms: • High nutrients • Upwelling • Seasonal conditions

  11. Primary Producers Common Name Blue-green algae (cyanobacteria) Red algae Brown algae Green algae Coccolithophorids Dinoflagellates Diatoms Seagrass

  12. Some important types of zooplankton • Crustaceans: Copepods • Krill • Cladocera • Mysids • Ostracods • Cnideria (True jellies, Man-of-wars, By-the-wind-sailors) • Ctenophores (comb jellies) • Urochordates (salps and larvacea) • Worms (Arrow worms, polychaetes) • Pteropods (planktonic snails)

  13. Importance of krill in Antarctic food web

  14. Chaetognath Copepod Crab larvae jellies

  15. Fish larvae Queen Trigger fish Egg to Juv.

  16. tunicate Jelly-like house Oikopleura Marine snow

  17. Marine Snow

  18. Marine Snow A major component of marine snow is fecal pellets Base of Florida Escarpment covered with marine snow. Octocorals attach to steep sides and under ledges to avoid burial.

  19. Marine Snow

  20. Ocean Productivity

  21. Importance of Phytoplankton Phytoplankton is the base of the food chain. Phytoplankton population decline causes zooplankton and apex predators to decline .

  22. Regional productivity • Photosynthetic productivity varies due to: • Amount of sunlight • Availability of nutrients • Thermocline (a layer of rapidly changing temperature) limits nutrient supply • Examine three open ocean regions: • Polar oceans (>60° latitude) • Tropical oceans (<30° latitude) • Temperate oceans (30-60° latitude)

  23. Productivity in tropical, temperate, and polar oceans Zooplankton

  24. Productivity polar oceans

  25. Productivity in tropical oceans

  26. Productivity in temperate oceans

  27. Diurnal vertical migration Organisms within the deep scattering layer undertake a daily migration to hide in deep, darker waters during daytime

  28. Plankton Patchiness • Zooplankton not distributed uniformly or randomly • Aggregated into patches of variable size

  29. Causes of Patchiness • Aggregations around phytoplankton • - If phytoplankton occurs in patches, grazers will be drawn to food • - Similar process that led to phytoplankton patches will form zooplankton patches • Grazing “holes” • Physical process • - Langmuir Cells • - Internal waves

  30. Accumulation of Plankton in Langmuir Cells • Buoyant particles and upward-swimming zooplankton will accumulate over downwelling zones

  31. Langmuir Cells

  32. Internal Waves • Underwater waves propagated along the thermocline • Generated by overflow over rough topography • Much greater amplitude than surface waves

  33. Satellite image of internal wave

  34. Deep sea scattering layer: Composite echogram of hydroacoustic data showing a distinct krill scattering layer. Black line represents surface tracking of a blue whale feeding patchiness

  35. Planktivory

  36. Sponges

  37. Jellyfish Filter feeding in Aurelia (Moon Jelly)

  38. Corals Hermatypic Ahermatypic

  39. Bivalves

  40. lancet

  41. Christmas tree worms

  42. Filter feeding in Krill the six thoracopods form a very effective "feeding basket"

  43. Barnacle feeding Modified legs

  44. tunicate Oikopleura Predator Filter feeder

  45. Gill Rakers

  46. Includes: manta rays, basking shark, whale shark, megamouth, paddlefish, gizzard shad, menhaden, and bighead carp.

  47. Flamingo

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