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