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BACTERIOPLANKTON: DISTRIBUTION AND ECOLOGY

BACTERIOPLANKTON: DISTRIBUTION AND ECOLOGY

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BACTERIOPLANKTON: DISTRIBUTION AND ECOLOGY

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  1. BACTERIOPLANKTON: DISTRIBUTION AND ECOLOGY

  2. Role of bacteria in the carbon cycle

  3. Recall

  4. How to determine numbers of cells and biomass • Direct count • Culture • Fluorescence microscopy • ATP • Identify environmental microbes by PCR, RFLP, and sequencing

  5. SEM micrograph of bacterioplankton Fluorescence micrograph of bacterioplankton

  6. ASSUMPTIONS • Growth of bacteria substrate-limited • Thus, bacterioplankton most common in layers where primary production highest (epilimnion) • Low biomass in metalimnion • A second maximum in the hypolimnion • Numbers lowest in winter

  7. Thus, bacterioplankton should vary according to season and depth

  8. Co-occurrence of phytoplankton and bacterioplankton

  9. Numbers and relative occurrence of bacterioplankton in a Michigan Lake from October to July

  10. Numbers and production rates of bacterioplankton through the seasons

  11. Lake Hancza, the deepest lake in Poland

  12. Gotkowska-Płachta A. , Niewolak S. , Korzeniewska E. 2003. VERTICAL DISTRIBUTION AND SEASONAL CHANGES IN THE NUMBER OF BACTERIOPLANKTON IN THE WATER OF LAKE HAŃCZA, PARTICULARLY IN THE PERIOD OF RESERVOIR SUMMER STRATIFICATION. EJPAU 6(2), #10. Figure 2. Vertical changes of temperature, oxygen saturation and number of planktonic bacteria (thousands of cells/ 1 cm3 of water) in the water of Lake Hańcza (at station 1) during summer stratification of the lake in 1997 and 1998. A � temperature, B � oxygen, C � planktonic bacteria

  13. Gotkowska-Płachta A. , Niewolak S. , Korzeniewska E. 2003. VERTICAL DISTRIBUTION AND SEASONAL CHANGES IN THE NUMBER OF BACTERIOPLANKTON IN THE WATER OF LAKE HAŃCZA, PARTICULARLY IN THE PERIOD OF RESERVOIR SUMMER STRATIFICATION. EJPAU 6(2), #10. Figure 3. Vertical changes of temperature, oxygen saturation and number of planktonic bacteria (thousands of cells/ 1 cm3 of water) in the water of Lake Hańcza (at station 1) during summer stratification of the lake in the years 1999 and 2000. A � temperature, B � oxygen, C � planktonic bacteria

  14. Also controlled by • Temperature (as you have seen, usually highest in warm months) • pH (grow best in circumneutral pH) • Often restricted by nutrient availability, especially phosphate

  15. Model of seasonal control of bacterioplankton

  16. DOC: Amino Acids and Carbohydrates • Concentrations low • Assimilated faster in aerobic water than in anaerobic water • Assimilation faster in warmer water than in cooler water • Humic acids degrade very slowly and may be linked to other organics

  17. Uptake of DOC • As cells die, 5-35% released as DOC • Extracellular release of DOC by primary producers a major source • Most DOC released by primary producers in the euphotic zone • Bacterial assimilation peaks after peak release of DOC by phytoplankton

  18. Distribution of carbon fractions versus rates of uptake

  19. The microbial loop

  20. Idealized daily fluctuations of various parameters that impact bacterial uptake

  21. Organic content of suspended particulate matter (POC) through the seasons

  22. Phytoplankton production relative to rates of sedimentation of POC

  23. Rates of turnover by large and small bacterioplankton

  24. Summary for bacterioplankton. See Table 17-16 (p. 523)