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Algae: Overview and Importance for Earth’s Atmosphere

This text provides an overview of algae and their importance for Earth's atmosphere, including their role in carbon dioxide cycling and oxygen production. It also discusses the evolution of algae and their impact on the atmosphere throughout history.

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Algae: Overview and Importance for Earth’s Atmosphere

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  1. Algae: Overview and Importance for Earth’s Atmosphere

  2. Earth’s Atmosphere: Not Much of It Mass Atmosphere = 5.2 x 1018 kg Mass Oceans = 1.4 x 1021 kg Mass Earth = 6.0 x 1024 kg Live Biomass = 1 x 1015kg Carbon Dioxide = 3 x 1015 kg Trunover Time for carbon dioxide = 5 years in atmosphere, centuries in oceans

  3. Carbon dioxide cycles between low values in summer and higher values in winter in the Northern Hemisphere due to seasonal differences in photosynthesis. Annual input from fossil fuels and deforestation: 3 x 1013 kg carbon dioxide. Half accumulates in the atmosphere, rest is absorbed in oceans, leading to acidification. Pre-industrial carbon dioxide level was 280 ppm, now 380 ppm.

  4. Early Earth Atmosphere: No Oxygen Lots of Carbon Dioxide, Methane, Water Vapor, Hydrogen

  5. Cyanobacteria and Oxygenic Photosynthesis About 3 Billion Years Ago. Water is the electron donor. CO2 + H2O  CH2O + O2

  6. Oxygenic photosynthesis is complicated. It requires two photosystems and is thought to have arisen only once in the course of evolution.

  7. Modern Stromatolites Fossil Stromatolite (2.5 Billion Years Old) Banded Iron Formation Oxygen Was A Poison to Early Life Forms on Earth. Took about 1 billion years before oceans and atmosphere were fully oxygenated

  8. Oxygen in the air allowed the evolution of eucaryotes and aerobic respiration, finally leading to the world’s life forms present today.

  9. Oxygen also produced the ozone shield which protects water in the upper atmosphere from boiling away as hydrogen Ozone in the upper atmosphere (derived from O2) protects against the splitting H2O to H and OH, with H escaping to space. Earth has lost about 25% of its water while water is nearly all gone on Venus and Mars.

  10. Greenhouse Gasses: Water Vapor Carbon Dioxide* Methane* Nitrous Oxide* *Increasing Due To Human Activity

  11. 1500 Ma 60 Ma Evolution of the modern algae orders.

  12. 600 Ma to present – evolution of animal kingdom

  13. SNOWBALLEARTH 1st - 2200 MYA 2nd – 850 MYA

  14. Plate tectonics provides a resupply of carbon dioxide to the atmosphere

  15. 50 MYA Diatoms and Grasses Reduce Carbon Dioxide to Very Low Levels Diatoms Grasses

  16. Evolution and impacts of algae on the atmosphere continue today…

  17. In this course we emphasize the ecology and biology of the algae rather than the taxonomy. Main groups we will cover: Cyanobacteria (blue-green algae) Green Algae Red Algae Brown algae – brown seaweeds, kelps, diatoms Dinoflagellates Coccolithophores Others

  18. Cyanobacteria Cell Structure

  19. Nostoc colony Nostoc filaments with N2-fixing heterocysts

  20. Ceramium – filamentous red seaweed

  21. Porphyridium – Unicellular Bangean Red Algae

  22. Chlamydomonas

  23. Enteromorpha Monostroma Ulva

  24. Diatoms Heterokont in sexual stage

  25. Red-Tide Forming Dinoflagellates Desmokont Dinokont Prorocentrum Lingulodinium

  26. Red Tides

  27. Coccolithophores Haptophytes w/ two smooth flagella and a coiled hapto- nema Emiliania huxleyi Ca + 2HCO3 ---> CaCO3 + H2O + CO2

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