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BACTERIOPLANKTON: DISTRIBUTION AND ECOLOGY
Role of bacteria in the carbon cycle
Recall
How to determine numbers of cells and biomass
• Direct count• Culture• Fluorescence microscopy• ATP• Identify environmental microbes by PCR, RFLP,
and sequencing
SEM micrograph of bacterioplankton Fluorescence micrograph of bacterioplankton
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
Thus, bacterioplankton should vary according to season and depth
Co-occurrence of phytoplankton and bacterioplankton
Numbers and relative occurrence of bacterioplankton in a Michigan Lake from October to July
Numbers and production rates of bacterioplankton through the seasons
Lake Hancza, the deepest lake in Poland
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
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
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
Model of seasonal control of bacterioplankton
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
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
Distribution of carbon fractions versus rates of uptake
The microbial loop
Idealized daily fluctuations of various parameters that impact bacterial uptake
Organic content of suspended particulate matter (POC) through the seasons
Phytoplankton production relative to rates of sedimentation of POC
Rates of turnover by large and small bacterioplankton
Bacteria in Rivers and Lakes, a Study
De Araujo, M.F.F. and M.J.L. Godinho. 2008. Seasonal and spatial distribution of Bacterioplankton in a fluvial-lagunar system of a tropical region: density, biomass, cellular volume and morphologic variation. Brazilian Archives of Biology and Technology. 51(1): doi: 10.1590/S1516-89132008000100024
Summary for bacterioplankton. See Table 17-16 (p. 523)
RIVERS RESERVOIRS LAKES
Bacterioplankton abundance
High to very high Moderate to high Low
Bacterioplankton production
Low but increasing with stream order
Low to moderate Low
Bacterioplankton respiration
High Moderate Low
Bacterioplankton Mortality
High Moderate High
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