1. Microbial Marine Ecology
Supervisor: Dr. Sahar El-shatoury
By: Najat Abdulrahim Mohammed
Water As A Microbial Habitat !

2. Contents (1): (What-How-why)s
1) What is the?
• The ecosystem?
• Water content on Earth?
• Water categories ?
• Water zones ?

3. 1. Ecosystem.
• The community of organisms in an area and the
physical factors with which those organisms
interact.
Species
Habitat
Abiotic
factors
Abiotic factors:
Temperature, water salinity,
sunlight, soil, precipitation.

4. Ecosystem Components:

5. Water content on Earth:
• 75% of the earth’s surface is water.
• Most biosphere is water ecosystem.

6. Water categories:
Fresh
Water
• Standing
(lakes and
ponds)
• Flowing
(rivers and
streams)
Both
• Wet lands
Areas that
are saturated
with water
either
permanently
or seasonally
Marine
Water
• Seas
• Oceans

7. Water Zones:

8. Microbes in the Ecosystem:
• The main role of microbes :
1. Decomposers.
2. Maintain the balance of the ecosystem.
• Understanding the diversity of
microorganisms helped the microbiologists to
solve some problems as global warming,
diseases and pollution.

9. Microbial communities:
• Microbes are very divers according to the
location that is found in
• It maybe found in expected areas: rivers, lakes
and the oceans..
• Also it’s found in water-saturated zones ( wet
lands) in materials we usually describe.

10. Dominant Factors That Affect The
Aquatic Microbial Environment:
• pH:
It can range from acidic to extremely alkaline.
• Temperature:
• Lowest degree: -5 to -15 °C
• Highest degree: 121 °C
Example:
Thermus aquaticus the source of temperature stable
DNA polymerase which makes PCR possible.

11. Dominant Factors That Affect The
Aquatic Microbial Environment:
• Penetration of sunlight
• Dissolved Oxygen
• Mixing nutrients
• Waste products
• Other gases ( Methane, Nitrogen and Hydrogen).

12. 1. Dissolved Oxygen
• The solubility of oxygen increases in colder
temperature and higher atm. pressure.
• In the very deep oceans oxygen concentrations
increase with depth.

13. 1. Dissolved Oxygen
• In tropical lakes and summer time temperate
lakes may become oxygen limited only meters
below the surface. Aerobic microbes consume all
surface oxygen forming anoxic zones.
• Anaerobic microbes grow ( phototrophic,
heterotrophic) on the lower regions according to
light penetration.

14. Carbon Dioxide (CO2)
• The pH of water is determined by the dissolved
CO2 in equilibrium with the air.
In the freshwater pH Is controlled by:
(weakly buffered)
1. Nature of terrestrial input (minerals) .
2. Rate of CO2 removed by autotrophs .

15. Carbon Dioxide (CO2)
• In the marine water pH Is controlled by:
(strongly buffered)
Carbonate ooze

16. Carbonate Equilibrium System
Calcium carbonate, [Ca][CO3] is a very common mineral. Limestone is
one familiar form of calcium carbonate. Acids in acid rain promote
the dissolution of calcium carbonate by reacting with the carbonate
anion.
One that is important in surface waters is the
carbonic acid/bicarbonate buffer.

17. 3- Other gazes:
• Nitrogen used as nitrogen source by nitrogen
fixers.
• Hydrogen: waste product of vital processes.
• Methane.
All vary in there water solubility and methane is
the least soluble of the three.

18. 4- Light penetration :

19. Organic Carbon availability:
Water
Fresh Marine
• Organic carbon
is fixed by
plants and
macroalgae
• Organic carbon
enter the
system by
terrestrial run
off.
• In open ocean all
organic carbon is
product of microbial
autotrophy
• One half of carbon
fixation on Earth is
made in oceans

20. Photic zone
Photic zone
Marine Fresh
Photic zone maybe
only
a meter or two in depth
In areas where water
seems crystal clear
Photic zone ranges
from 150 – 200 m

21. 5- Solar Radiation:
• Solar radiation intensity can change the water
temperature, so the water starts to form layers of
water according to its temperature.
• The warm water will floating above the cold
water this layers will remain separated until any
changes in weather, which will mix the two
layers together after cooling the upper layer.

22. Thermocline

23. Thermocline:

24. •Thank you!