Phytoplankton 2

1. Phytoplankton 2 Community Dynamics

2. photosynthesis

3. Photosynthesis: relationship between light & temperature 5C 15C 25C

4. Photoinhibition

5. Euglena with red masking pigment

6. Flotation mechanisms

7. Flotation Mechanisms • Increase surface:volume to increase frictional resistance. e.g. Ceratium

8. Flotation Mechanisms • Production of mucilage. e.g. Gloeocapsaand Staurastrum

9. Flotation Mechanisms • Gas vacuoles. e.g. Anabaena

10. Flotation Mechanisms • Accumulation of lipid. e.g. Botryococcus

11. Flotation Mechanisms • Change buoyancy by exchanging monovalent and divalent ions. Documented for dinoflagellates in marine environments, not in freshwater.

12. Flotation Mechanisms • Swimming by flagella. Ceratium Pandorina Euglena Cryptomonas

13. Growth rate & competition

14. Size and Growth Rate

15. Competition relative to the concentration of a limiting nutrient Compare with Figure 15-4

16. Growth Rate • Examples of growth and competition • = Cosmarium= Staurastrum

17. Competition between two diatoms

19. Vitamin Requirements • Compare with Table 15-7

20. Metabolic Processes

21. Modes of succession

22. Seasonal Succession

25. Winter Populations and Spring Maximum • Growth declines in winter when temperature is low and light is low (Figure 15-9). • Sometimes production under ice cover can be significant (Figure 15-10). • Sometimes spring maximum begins with growth under ice. • Usually spring maximum after turnover and dominated by a single species (Figure 15-11).

26. Seasonal succession of major groups of phytoplankton in Lake Erken, Sweden

27. Winter production beneath ice

28. Production and loss of Asterionella in Lake Windermere, England (28 April – 30 June)

29. Spring Decline and Summer • Decline in nutrients (especially Si) in the photic zone • In very productive lakes (high phosphate loading) Diatoms Greens Bluegreens

30. Fall Turnover and Autumn Circulation • Temperatures decline • Reduced grazing by zooplankton • High nutrient availability Dominated by large cells and filaments; usually dominated by diatoms

31. Limitation and Availability of Growth Factors in Reservoirs Consider differences between lakes and reservoirs

32. Parasitism and Grazing • Parasites: • Chytrids • Viruses • Grazers: • Heterotrophic Protists • Zooplankton (see Figure 15-13) • Cladocerans • Copepods • Rotifers

33. Competitive Interaction & Species Diversity • Diversity indices • Species diversity declines as fertility increases • In eutrophic waters, diversity increases in the summer and declines in the winter.

34. Vertical Distribution of Phytoplankton Biomass in Lakes and Reservoirs • Figure 15-14 Chlorophyll a in Lawrence Lake • Figure 15-15 Carotenoids in Lawrence Lake • Figure 15-16 Phaeophyton in Lawrence Lake

35. Rates of Primary Production by Phytoplankton Measured as mg carbon fixed per cubic meter per day Figure 15-22 for Lawrence Lake. Figure 15-24 for Wintergreen Lake

36. River plankton production

37. Light utilization

38. Efficiency of Light Utilization • Utilization of light between 350 and 700nm (Table 15-10) • In water column efficiency relatively low at surface (light above saturation) • Efficiency increases slightly with depth but overall carbon fixation decreases (Figure 15-27)

39. Utilization of light between 350 and 700nm

40. Efficiency increases slightly with depth but overall carbon fixation decreases

41. Concluding remarks

42. Extracellular Release of Organic Compounds • Loss of photosynthate • Many compounds are inhibitory (allelopathy)

43. Diurnal Changes in Phytoplankton • Relative to light saturation • Relative to synchronous division and metabolism • Vertical migration

44. Horizontal Variation • Related to morphometry of lakes and reservoirs (e.g. Figure 15-12) • Related to longitudinal zones within reservoirs and streams

45. Summary Table 15-14