Lec 7

Question 1

MISCONCEPTIONS ABOUT WATER:

Answer 1

1. ) Tends to be well-mixed
   - Water is not homogenous
   - Stratification
2. ) Water is static
   - Aquatic systems are spatially and temporally dynamic

Question 2

(MICROBIAL HABITATS IN THE AQUATIC ENVIRONMENT)

Physical & Chemical Characteristics:

Answer 2

1. ) Photic zone: 0-200m allows light penetration and photosynthesis
2. ) Aphotic zone: No light, little heterotrophic activity and no photosynthesis
3. ) Turbid waters: Light penetration < 1m

Question 3

Stratification =

Answer 3

Physical structuring

of aquatic environments established by temperature and salinity differences

Question 4

AQUATIC MICROORGANISMS:

Answer 4

1. ) Planktonic (plankton) = Suspended in water column
   - Phytoplankton (1* Producers) (Algae & cyanobacteria)
   - Bacterioplankton (Consumers) (Heterotrophic bacteria)
   - Zooplankton (Consumers) (Protozoa)
2. ) Benthic
   - At bottom of body of water

Question 5

Surface Zone =

t.f.:

Answer 5

= Photic Zone

t.f.: Lots of microbes

Question 6

Marine phytoplankton account for ≃

& comprised of…

Answer 6

= 50% global primary production

…50% cyanobacteria; 50% eukaryotic algae

Question 7

Primary production is limited by

Answer 7

Availability of N & P
temperature
turbidity
vertical mixing

Question 8

Numbers of primary producers = ____ (benthic zone) to _____ (surface zone)

Answer 8

10/mL (benthic zone)

108/mL (surface zone)

Question 9

DOM = dissolved organic material
POM = particulate organic material
Only difference is…
What will eat these nutrients?

Answer 9

= dissolved organic material
= particulate organic material
…the size
Heterotrophic bacteria

Question 10

Viral shunt =

Answer 10

the lysing of both phytoplankton and heterotrophic bacteria by viruses

Question 11

The majority of DOC comes from...
DOC becomes...
CO2 and nutrients fuels new...
Phages also cause...
Zooplankton consumed by...

Answer 11

…phytoplankton
…Remineralized into CO2 and nutrients by bacterioplankton
…1* production (≃ 80% of marine primary production)
…6-26% of DOC released by lysis of both phytoplankton and bacterioplankton
…larger organisms

Question 12

Nutrients and carbon can also be…

Answer 12

…stored for a long period of time in the depths of the ocean

Question 13

Benthic Zone =
microbial numbers?
Important for?

Answer 13

= Transition zone between water column and mineral subsurface (bottom of the water column)
…Much higher microbial numbers than water column (due to nutrients and dead cells that sink to the bottom = really allows a bunch of organisms to live at the bottom)
…nutrient cycling

Question 14

What is the most abundant biological entity on earth?

Answer 14

viruses

Question 15

marine viruses impact…

Answer 15

…bacteria via cell lysis, horizontal gene transfer (transduction) and modification of host metabolism

Question 16

marine viruses are important for…

Answer 16

…generation of DOM in oceans

Question 17

marine viruses can also infect

Answer 17

fish and crabs

Question 18

Biological pump =

Answer 18

= the sequestration of carbon in the deep ocean
(Idea = if it is sequestered down in the deep ocean = it is not in the atmosphere SO = good thing (see slide 11 to see the map again))

Question 19

Virus efficiency debate:

Answer 19

1. ) Viruses increase the efficiency of the biological pump by infecting host cells in the ocean and accelerating the sinking rate
2. ) Viruses decrease the efficiency of the biological pump by causing lysis of host cells and therefore, the released nutrients are now available to other organisms instead of being transferred to the deep ocean

Question 20

By adding _________ to the ocean the phytoplankton would be less susceptible to viral infection and ________ the efficiency of the biological pump

Answer 20

fertilizers

increase

Question 21

Ocean Geo-engineering idea =

issue =

Answer 21

= adding nutrients to the ocean = makes phytoplankton healthier (in theory) = will be more resistant to viruses (prevents infection and lysis) = will be able to sink down to depths of ocean
= Algae blooms = suck up most nutrients and oxygen = create dead zones

Question 22

Biofilm =

Answer 22

= Layer of organic matter and microorganisms formed by the attachment and proliferation of bacteria on the surface of an object

Question 23

Biofilms are present in

Answer 23

aquatic environments

Question 24

Biofilm benefits:

Answer 24

• Protects from protozoan grazing (predators)
• Proximity to nutrients
• Can protect against toxicity
• Can alter microenvironment
• Easier to swap DNA with buddies
• Cell-cell signaling = cooperative work

Question 25

Biofilm disadvantages:

Answer 25

- Tooth decay - Comprised medical implants - Corrosion of metal pipes

Question 26

Microbial Mats are essentially just

Answer 26

a different type of biofilm

Question 27

Microbial Mats have

Answer 27

different groups laterally compressed into thin mats

Question 28

Microbial Mats support

Answer 28

most of major biogeochemical cycles and thus largely self-sufficient

Question 29

Microbial Mats are often associated

Answer 29

with extreme environments

Question 30

Lentic = | Lotic =

Answer 30

= still water (lakes) | = flowing water (streams/potential for a lot of disturbance)

Question 31

LAKE SECTIONS BASED ON TEMPERATURE: (3)

Answer 31

1. ) Epilimnion – uppermost layer, warmer and higher O2 2. ) Metalimnion – middle layer, contains thermocline (steepest temperature gradient) 3. ) Hypolimnion – bottom layer, colder and anoxic

Question 32

Neuston layer =

Answer 32

= very small layer on top of freshwater

Question 33

Neuston layer is sometimes considered

Answer 33

an extreme environment because of radiation, temperature fluctuations, accumulation of toxic substances

Question 34

OTHER AQUATIC ENVIRONMENTS: (4)

Answer 34

Brackish Waters Hypersaline Waters Subterranean Waters Wetlands