Download Energy Nutrients (carbon, nitrogen, phosphorus, oxygen, sulfur, etc

The Ocean as a Microbial Habitat
Matthew Church
Marine Microplankton Ecology
OCN 626/Fall 2008
The Ocean as a Habitat
• Energy, nutrients, and life
• Description of the physical, chemical,
and biological environment
• What does life require?
– Energy
– Nutrients (carbon, nitrogen, phosphorus, oxygen,
sulfur, etc., etc.)
– Electron donor-a source of reductant
– Electron acceptor- required for respiration
• Common habitat controls
microorganism distributions and
abundance
–
–
–
–
–
Light
Nutrients
Temperature
Pressure
Redox environment
Energy flows, matter cycles
Sources of energy for life
in the sea
• Light-aside from hydrothermal vents,
sunlight is the ultimate energy source
for life in the sea (phototrophy).
• Chemical-both organic and inorganic
compounds (chemotrophy).
H2S
Glucose
Nutrient sources
• Nitrogen: protein, nucleic acids
– NO3-, NO2-, N2, NH3, organic N
• Phosphorus: nucleic acids, lipids
– PO43-, organic P
• Carbon: nucleic acids, protein, lipids,
carbohydrates, etc.
– CO2, organic C
• Sulfur: amino acids, protein, lipids
– SO42-, S, H2S, organic S
Spatial gradients in the marine
environment
• Light, Salinity, Nutrients, Temperature, Pressure
Scales of variability are important
Note that increasing
time scales generally
correspond to
increasing space
scales
Time-space scales of physical
processes
F
Z
P
B
From T. Dickey
•Generation
time of a tree:
years
•Generation
time of
microbe:
minutes to
days
Temperature-salinity plot from Station ALOHA showing the time-dependent
changes in physical ocean properties. Note greater variability in physical
environment in upper 200 m; deep sea (>1000 m) largely invariant with time.
~30X variation in
temperature in the
surface ocean
~4X variation in
temperature in the
deep sea
NOAA-NESDIS-National
Oceanographic Data Center
The ocean is stirred more than mixed
Sea Surface Temperature
(°C)
Chl a
(mg m-3)
Spatial discontinuities at
various scales (basin,
mesoscale, microscale)
in the ocean habitat play
an important role in
controlling the growth of
microorganisms.
Yoder, 1994
Shelford’s Law of Tolerances:
The distribution and abundance of an organism will be
controlled by that environmental factor for which the
species has the narrowest range of tolerance.
Organisms have evolved specific tolerances to habitat
variables (light, temperature, nutrients, pH, oxygen, salinity)
Group
Classification
Minimum
Optimum
Maximum
Psychrophile
<0
10-15
>20
Psychrotroph
0
15-20
>25
Mesophile
10-15
30-40
<45
Thermophile
45
50-85
>100
Most organisms in the oceans are psychrophiles and mesophiles
Oceans
Oceans
Divisions per day
Temperature plays an
important role in
controlling plankton
growth and distributions.
In this example, diatoms
have a wider range of
optimal temperatures
than flagellated
phytoplankton.
Temperature (oC)
Which group of
plankton would
be predicted to
have a more
cosmopolitan
distribution?
Light transmission through the
atmosphere and ocean
Energy impinging on the
Earth’s surface is most
intense in visible portion
of the spectrum
UV
Visible
Infrared
Profile of irradiance with depth
0
0
20
20
40
40
60
60
Depth (m)
Depth (m)
In the blue-green regions of the visible spectrum, sunlight penetrates
deep into the ocean
80
100
120
100
120
412 nm
510 nm
665 nm
140
80
412 nm
510 nm
665 nm
140
160
160
0
20
40
60
80
100
-2
-1
Downwelling irradiance (W cm nm )
0.1
1
10
100
1000
-2
-1
Downwelling irradiance (W cm nm )
Data from Station ALOHA
Differences in
growth as a
function of light
energy by
4 isolates of
Prochlorococcus
Vertical Profiles of Nutrients
Nutrient distributions with depth (pressure) at Station ALOHA
NOAA-NESDIS-National Oceanographic Data Center
Nutrient availability is governed by physics:
mixing, upwelling, advection, diffusion
AND biology: the balance between assimilation
and remineralization
7 years of ocean chlorophyll from satellites
Mean
Maximum
Minimum
High latitudes are
highly variable, central
gyres more stable
Biological variability in space and time
Spatially coherent interannual variability in selected
ecosystems (equator for example) but most ocean
ecosystems appear highly variable in space and time
The mesopelagic
zone is an important
region of
decomposition.
Photosynthetically
derived material
produced in the welllit upper ocean sinks
to the ocean’s
interior-microbes in
the mesopelagic rely
on this sinking
material for energy.
0
Depth (m)
1000
Pacific
Atlantic
2000
3000
4000
0
10
20
30
40
NO3- + NO2- (mol L-1)
50
Basin scale
differences in
nutrient
concentrations
controlled by biology
(decomposition) and
physics
(thermohaline
circulation)
The
bathypelagic
Barophilic (or piezophilic)
microorganisms
• Barophilic microorganisms
grow optimally at pressures
in excess of 1 atm.
• Low temperatures and high
pressures both solidify
lipids (cell membranes).
• Microorganisms can adapt
to changes in pressure by
increasing or decreasing the
fluidity of cell membranes
through changes in fatty
acid composition (through
production of unsaturated
fatty acids)
Yayanos et al. (1981) PNAS
Interactive influences of pressure and temperature on the
growth of a bacterium isolated from Mariana Trench