10/7/24

Question 1

_________ by bacteria inside legume ______ ________

Answer 1

Nitrogen fixation; root nodules

Question 2

Nitrogen fixation

Answer 2

N2 (gas) –> NH4 (great fertilizer)

Question 2

Describe the nitrogen cycle

Answer 2

Bacteria: nitrogen gas (N2) -> nitrogen-fixing bacteria: NH3 (via N fixation) -> assimilation (bacteria, plants, animals): N-protein (animal, plant) -> bacteria: NH3 (via decomp) -> bacteria: NO3

Question 3

Eutrophication leads to

Answer 3

over-fertilized waters

Question 4

T or F: Freshwater fish contain more 13C than marine fish

Answer 4

F: Marine fish contain more 13C than freshwater fish

Question 5

The fish problem

Answer 5

Decrease in water quality of freshwater

Increase in demand for (water) power

Overfishing of freshwater fish

Question 6

Shifting baselines

Answer 6

Change evaluated based on current state
- Each generation = new baseline

Question 7

What assumption is made in Shifting baselines?

Answer 7

“current state is normal”

Question 8

Aquaculture

Answer 8

Raising aquatic organisms under controlled conditions

Question 9

What are the benefits of aquaculture?

Answer 9

Reliability (controlling conditions)

Can be small-scale

Reduce fishing of wild stocks

Uses less fossil fuel than capturing fishing
- Less use of boats to travel from place to place to capture fish

• reduces by-catch

Question 10

Environmental impacts of aquaculture

Answer 10

High density → disease, antibiotics

Waste production
- High amounts of waste(urine, feces) is produced

Farmed fish escape to interbreed with or spred disease to wild fish

Animals often fed fish meal
- Salmon chow

Question 11

What happens during by-catch

Answer 11

“Non-target” species are caught

Non-specific equipent i used (e.g., nets)
- there is no target-specific catching system to only catch the target

Question 12

What are example of modern gillnet by-catch?

Answer 12

sea lion
sharks
sea turtles

Question 13

By-catch impact =

Answer 13

discards (what we throw away) / total caught (what we catch)

Question 14

Why did the steller’s sea cow go extinct?

Answer 14

Slow
Similar to beef in taste
Blubber for cooking
- Rendered for lamp oil

Milk of cows, butter
Hide → functional equipment (shoes, belts)

Time to reproductive maturity (manatee: 5 years)

Low reproductive output (1 calf/litter, 12 month gestation)

Only found in the pacific northwest (low distribution)

Question 15

What is the main cause of death for marine whales?

Answer 15

collisions with boats

Question 17

Where does most of today’s nitrogen fixation come from?

Answer 17

Fertilizer

BNG (agr)

Combustion

Question 18

What are the most important sources of N?

Answer 18

Commercial fertilizer (53%)
Livestock manure (31%)
Legumes (9%)
Sewage (6%)
Industry (1%)

Question 19

Dead zone

Answer 19

Reduced levels of oxygen in the water

Question 20

Describe how eutrophication leads to dead zones.

Answer 20

Lost agr fertilization (nutrients) —> Mississippi river —> gulf of mexico —> algal growth —> dead algae (organic compounds —> decomp bacteria consume CO2 —> fish, etc killed —> dead zone