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

2. Earth’s Atmosphere: Not Much of It Mass Atmosphere = 5.2 x 10 18 kg Mass Oceans = 1.4 x 10 21 kg Mass Earth = 6.0 x 10 24 kg Live Biomass = 1 x 10 15 kg Carbon Dioxide = 3 x 10 15 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. CO 2 + H 2 O  CH 2 O + O 2

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. Ozone in the upper atmosphere (derived from O 2 ) protects against the splitting H 2 O 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. Oxygen also produced the ozone shield which protects water in the upper atmosphere from boiling away as hydrogen

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

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

12. 600 Ma to present – evolution of animal kingdom

13. SNOWBALL EARTH 1 st - 2200 MYA 2 nd – 850 MYA

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

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

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 filaments with N 2 -fixing heterocysts Nostoc colony

20. Ceramium – filamentous red seaweed

21. Porphyridium – Unicellular Bangean Red Algae

22. Chlamydomonas

23. Ulva Enteromorpha Monostroma

24. Diatoms Heterokont in sexual stage

26. Desmokont Dinokont Dinoflagellates Red-Tide Forming Prorocentrum Lingulodinium

27. Red Tides

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