Microbiology of Water

Question 1

Aquatic primary producers

Answer 1

oxygenic photoautotrophs, phytoplankton

Question 2

Function of aquatic primary producers

Answer 2

Serve as a food source for chemoheterotrophs

Question 3

What do aquatic 1° producers depend on

Answer 3

• Temperature
• light availability
• nutrients

Question 4

Photic zone

Answer 4

The uppermost layer of a body of water that receives sunlight
* In clear water, light will penetrate to a maximum depth of 300 m

Question 5

Pelagic zone

Answer 5

Consists of the water column of the open ocean

Question 6

Marine Environments

Answer 6

• Open ocean
• Coastal waters
• Deep sea
• Hydrothermal vents

Question 7

Open Ocean (pelagic zone)

Environment? 1° productivity? 1° producer? T°C?

Answer 7

Oligotrophic: lack of inorganic nutrients
* Primary productivity is low
* Bulk of primary productivity comes from prochlorophytes
* In some regions, wind and ocean currents cause an upwelling of water from the ocean floor bringing nutrients to the surface and promoting productivity

T° are cooler and constant

Question 8

Adpatations seen in pelagic microorganisms

Answer 8

• Reduced size (high S/A ratio)
• High affinity transport system

Question 9

Trichodesmium

Environment? Type of organism? Pigment? Function?

Answer 9

• Found in nutrient poor ocean waters
• Filamentous cyanobacteria
• Contains phycobilins
• Nitrogen fixation

Question 10

Coastal waters

Environment? Productivity? 1° producer? Problems?

Answer 10

Eutrophic: Rich in nutrients
* 1° productivity is usually higher
* 1° producers = algae and cyanobacteria

Supports higher concentration of zooplankton and aquatic animals
* Can cause red tides

Nitrogen is a limiting nutrient

Question 11

Deep Sea

Environment? 1° productivity? 1° producer? T°C?

Answer 11

Between 300 and 1000m:
* Chemoheterotrophs degrade OM that falls from the photic zones
* 2-3°C - psychrophiles

Below 1000m:
* Oligotrophic
* Organic carbon is very scarce
* No light
* Very few microorganisms

Question 12

Hydrothermal vents

Answer 12

Source of heat, source of nutrients, electron donors, electron acceptors

Question 13

Freshwater Environments

Answer 13

• Lakes
• Rivers

Question 14

Oligotrophic lakes

Answer 14

N and P are limiting:
* 1° production is low
* OM is low and degraded completely
* Rate of O2 dissolution is higher than the consumption rate so O2 concentration remains high
* Clear water

Question 15

Eutrophic lakes

Answer 15

Nutrient rich
* 1° production is high
* OM is high
* Rapid depletion of dissolved O2 & low O2 concentration
* Anaerobic zones are created
* Poor light penetratio,

Question 16

Anaerobic zones

Eutrophic lakes

Answer 16

• support the growth of denitrifiers, methanogens and sulfate reducers
• Anaerobic photosynthesis uses H2S as electron donor and produces sulfate
• Excessive production of H 2S and the production of organic acids from fermentation can give the water a bad odor
• The lack of oxygen and/or presence
  of H 2S may kill fish and other aerobic organisms

Question 17

Summer stratification

Answer 17

Summer stratification
* As the air T increases, surface water is warmed resulting in the formation of a warm upper layer (epilimnion) which is less dense, & aerobic
* The colder, bottom layer (hypolimnion) is denser, & anaerobic, and is separated from the epilimnion by a zone of rapid temp. change (thermocline)
* Mixing in the spring and fall only

Question 18

Rivers

Answer 18

Ggood mixing/aeration ensures that OM is degraded effectively

Question 19

Pollution

Answer 19

Deliberate discharge of effluents into a waterway

Question 20

Biochemical oxygen demand (BOD)

Answer 20

Measure of the extent of pollution by OM

Question 21

Biofilms

Answer 21

Microbial cells embedded inside an ECM
* Usually produced by a mixed population of species
* ECM composed of proteins, polysaccharides, DNA
* Cells are more resistant to stresses