Lec 11

Question 1

Eutrophication

Answer 1

The process of nutrient enrichment, increased production of organic matter, and subsequent ecosystem degredation

Question 2

Main effect of eutrophication

Answer 2

Excessive plant and algal growth due to the increased availability of one or more limiting factors needed for photosynthesis

Question 3

Oligotrophic

Answer 3

Low productivity

Question 4

Mesotrophic

Answer 4

Moderate productivity

Question 5

Eutrophic

Answer 5

High Productivity

Question 6

Cultural (Anthropogenic) Eutrophication

Answer 6

Increases in plant and algal growth due to anthropogenic nutrient inputs

Question 7

Sources of anthropogenic eutrophication

Answer 7

Sewage

Fertilizer runoffs

Phosphorus-containing detergent

Question 8

Requirements for photosynthesis

Answer 8

Light

Nutrients

Water

CO2

Question 9

Principle of limiting factors

Answer 9

Certain ecological functions are controlled by whichever environmental factor is present in the least supply relative to demand

Question 10

Examples of limiting factors

Answer 10

Light

Water

Nutrients

CO2

Question 11

N as a limiting nutrient

Answer 11

N is the main limiting nutrient in terrestrial ecosystems

Question 12

Phosphorus as a limiting nutrient

Answer 12

P is the main limiting nutrient in freshwater ecosystems

Question 13

P retention by sediments

Answer 13

Sediment P

Biomass P

Dissolved P

Bioavailable P

Sediment P received P from the biomass and bioavailable P

Question 14

Iron (Fe) as a limiting nutrient in the ocean

Fe fertilization of the ocean possible effects

Answer 14

Reducing the availability of atmospheric CO2

Increasing ocean pollution and little effect on atmospheric CO2

Question 15

Which nutrients are limiting according to research from the 1960s-1980s

Answer 15

Carbon

Nitrogen

Phosphorus

Question 16

Experimental lakes area

Lake 227

prior to P additions

Answer 16

Oligotrophic (nutrient poor)

Question 17

Experimental lakes area

Lake 227

after to P additions

Answer 17

Eutrophic (nutrient rich)

Question 18

Lake 227

Seasonal dissolved CO2 concentrations

Pike population

Answer 18

Pike population increased with increased CO2

Question 19

Lake 226 experimental lake area

Answer 19

N and C lake vs N C P lake

NCP lake was eutrophic

Question 20

To reduce eutrophication, what must be decreased

Answer 20

Phosphorous

Question 21

Controls on primary production

Answer 21

Top down controls (herbivores)

Bottom-up controls (nutrients, water, light)

Question 22

Aquatic trophic cascade

Answer 22

Removal of a top predator

Increases the next species, decreases the species after and that cycle continues

Question 23

“Natural” aquatic ecosystem

Answer 23

Natural vegetation

Few nutrients

Weedbeds and snags

Lots of predators

Few minnows

Lots of Daphnia

Few Phytoplankton

Question 24

Stressors on aquatic ecosystem

Answer 24

Agriculture

cottages

sport fishing

high nutrients

few weedbeds/snags

few predators

lots of minnows

few daphnia

lots of phytoplankton

Question 25

P loadings to Lake Erie

Answer 25

Record setting algal bloom in Lake Erie caused by agricultural and meteorological trends

Question 26

Algal bloom also occurred in

Answer 26

Lake St.Clair in 2015

Question 27

Dissolved oxygen concentrations in lake Erie

Answer 27

Low concentrations in the middle and high concentrations on the outside due to eutrophication

Question 28

Nutrients vs fisheries yield

Answer 28

Increases until a threshold is reached then decreases

Question 29

Hypoxia

Answer 29

When water concentration is less than 2mg/L of O2 Reduced concentration of dissolved oxygen in a water body leading to stress and death in aquatic organisms

Question 30

Dead zones hypoxic

Answer 30

Hypoxic areas in aquatic ecosystems, typically a consequence of pollution, eutrophication, and high rates of decomposition, that are essentially devoid of life

Question 31

How a hypoxic zone forms

Answer 31

Nutrients enter the lake from inland rivers and streams The nutrients cause an algal bloom The algae dies and sinks to the bottom of the water Bacteria decompose the algae, respiring and consuming oxygen The temperature stratified water column of late-summer prevents the now oxygen depleted bottom water from mixing with the warmer, oxygenated upper water

Question 32

Gulf of Mexico dead zone formation

Answer 32

During the spring, sun-heated freshwater runoff from the Mississippi River creates a barrier layer in the Gulf, cutting off the saltier water below from contact with oxygen in the air Nitrogen and phosphorous in the freshwater runoff make a huge algae bloom. When the algae dies, it sinks to the bottom and decomposes, using up all the oxygen Starved of oxygen, a dead zone is formed. Organisms avoid the area or die in it. Winter brings respite, but spring starts the process anew

Question 33

Mississippi River Watershed

Answer 33

The six main subbasins of the Mississippi River Basin converge and discharge into the gulf

Question 34

Hypoxic zone in the Gulf of Mexico

Answer 34

Dead zone formed from deposition/runoff from the Mississippi River 4 million acres of habitat Comes from fertilizer and urban runoff

Question 35

Harmful Algal Blooms HABs

Answer 35

Made up of Cyanobacteria

Question 36

Cyanobacteria

Answer 36

Blue-green algae Phylum of bacteria that can photosynthesize

Question 37

Cyanobacteria toxins

Answer 37

Neurotoxins Hepatotoxins Dermatotoxins

Question 38

Microsystis sp.

Answer 38

Most common bloom-causing cyanobacteria. Can produce both neurotoxins and microcystins, a type of hepatotoxins

Question 39

Ndularia sp

Answer 39

Produces hepatotoxins called nodularins that can greatly harm humans

Question 40

Microcystin limit in Canada

Answer 40

1.5 microgram/L