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Biological Productivity in the Ocean

Biological Productivity in the Ocean. Part I. Overview. Productivity is related to photosynthesis, which is affected by sunlight and nutrients. Productivity is globally and seasonally variable. Feeding relationships are represented by food chains and food webs. Oceans are being overfished.

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Biological Productivity in the Ocean

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  1. Biological Productivity in the Ocean Part I

  2. Overview • Productivity is related to photosynthesis, which is affected by sunlight and nutrients. • Productivity is globally and seasonally variable. • Feeding relationships are represented by food chains and food webs. • Oceans are being overfished.

  3. Primary Productivity • Primary productivity = storage of energy in organic matter that comes from a non-organic source like the sun (not from other plants or animals) • Photosynthesisuses solar radiation. • Chemosynthesis uses chemical reactions. • 99.9% of the ocean’s biomass relies directly or indirectly on photosynthesis for food.

  4. Energy to Food:Photosynthesis

  5. Cyanobacteria

  6. Cyanobacteria Diatoms

  7. Cyanobacteria Dinoflagellates Diatoms

  8. Seagrass Dinoflagellates Diatoms

  9. Seagrass Dinoflagellates Kelp

  10. Seagrass Mangroves Kelp

  11. Photosynthesis vs. Respiration Photosynthesis: Creates food & releases O2, daylight only Respiration: Burns food, releases CO2, day and night

  12. Measurement of Primary Productivity • Directly – capture plankton in plankton nets • Measure radioactive carbon in seawater • Monitor ocean color with satellites • Green pigment chlorophyll • SeaWiFS

  13. Ocean Chlorophyll – SeaWiFS Satellite

  14. Factors Affecting Primary Productivity • Nutrient availability • Nitrate, phosphorous, iron, silica • Most from river runoff • Productivity high along continental margins • Redfield ratio – C:N:P proportions usually 106:16:1 for most phytoplankton

  15. Factors Affecting Primary Productivity • Solar radiation • Uppermost surface seawater and shallow seafloor • Compensation depth– net photosynthesis becomes zero (O2 produced = CO2 produced) • Euphotic zone—from surface to about 100 meters (330 feet)

  16. Light Transmission in Ocean Water • Blue wavelengths penetrate deepest • Longer wavelengths (red, orange) absorbed first

  17. Transmission of Light in Seawater

  18. Color in the Ocean • Color of ocean ranges from deep blue to yellow-green • Factors • Turbidity from runoff • Photosynthetic pigments (chlorophyll) • Eutrophic (high CHL) • Oligotrophic (low CHL) • Secchi Disk – measures water transparency

  19. Upwelling and Nutrient Supply • Cooler, deeper seawater is nutrient-rich. • Areas of coastal upwelling are sites of high productivity.

  20. Types of Photosynthetic Marine Organisms • Anthophyta • Seed-bearing plants • Macroscopic (large) algae • Microscopic (tiny) algae • Photosynthetic bacteria

  21. Anthophyta • Only in shallow coastal waters • Primarily grasses and mangroves Eelgrass

  22. Surfgrass

  23. Young Mangroves

  24. Young Lemon Shark in mangrove roots

  25. Upside-down Jelly in Mangrove roots

  26. Anthophyta Mangrove seed pods

  27. Mangrove Swamps in Florida Keys

  28. Macroscopic Algae • “Seaweeds” • Brown algae • Green algae • Red algae

  29. Macroscopic Algae Southern Sea Palm Elk Kelp

  30. Giant Kelp

  31. Giant Kelp Attach to rocks with holdfasts Unlike roots • Do not absorb nutrients • Do not take in water • Sole function is to hold plant in place

  32. Giant Kelp & Urchin Predators

  33. Microscopic Algae • Produce food for 99% of marine animals • Most are planktonic (“free-floating”) • Diatoms– tests (shells) made of silica • Coccolithophores– plates of calcium carbonate • Dinoflagellates – tail-like flagella

  34. Diatoms silica-shelled organisms dominant in colder water diatomaceous ooze Microscopic Algae

  35. Coccolithophores carbonate-shelled organisms dominant in warmer waters Microscopic Algae

  36. Coccolithophores carbonate-shelled organisms dominant in warmer waters Microscopic Algae

  37. Dinoflagellates Microscopic Algae Two whip-like flagella for propulsion

  38. Dinoflagellates “Red tides” Toxic algal blooms Phosphorescence But most not harmful Microscopic Algae Lingulodinium polyedrum

  39. Dinoflagellates Microscopic Algae Lingulodinium polyedrum, San Diego County

  40. Dinoflagellates Microscopic Algae Zooanthellae photosynthesize inside corals and provide nutrients: Symbiotic relationship

  41. Extremely small May be responsible for half of total photosynthetic biomass in oceans Very important: bring new nitrogen into marine ecosystems Cyanobacteria Photosynthetic Bacteria

  42. Photosynthetic Bacteria

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