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BIOL 381 > Eutrophication > Flashcards

Eutrophication Flashcards

1
Q

eutrophication is the process of _____ enrichment, increased production of ____ ____, and subsequent ecosystem ____

A

nutrient
organic matter
degradation

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2
Q

What is eutrophication?

Excessive plant and ____ growth due to the increased availability of one or more ____ ____ _____ needed for photosynthesis (____ production)

A

algal
limiting growth factors
primary

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3
Q

what’s the #1 symptom of eutrophication?

A

primary production (excessive growth)

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4
Q

T/F
eutrophication happens in aquatic systems, not on land

A

false

can happen on land, although not common (more common in aquatic systems)

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5
Q

What is cultural/ anthropogenic/ artificial eutrophication?
List 3 sources

A

increases in plant & algal growth due to anthropogenic nutrient inputs
- sewage
- fertilizer runoffs
- phosphorous-containing detergent (pre-1970’s)

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6
Q

Eutrophic = ___ productivity

Oligotrophic= ____ productivity

Mesotrophic= _____ productivity

A

high

low

moderate (meso=middle)
- nutrients here higher than limiting level

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7
Q

What are the 4 requirements for photosynthesis (primary production)

A
  • light
  • nutrients (N, P, etc)
  • water
  • CO2
  • any of these can be the limiting factor in an ecosystem
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8
Q

What term does this describe:

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

A

Liebig’s Law of the Minimum
ie Principle of Limiting Factors

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9
Q

List 5 things that can be limiting factors

A
  1. water
  2. light
  3. nutrients
  4. CO2
  5. biotic factors (predators, competition, etc)

*note #1-4 are the requirements for primary production

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10
Q

the most limiting factor determines the ___ ___

A

yield potential

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11
Q

what’s the main limiting factor in freshwater?

In terrestrial ecosystems?

A

freshwater- phosphorous
*majority of P is found in rocks

terrestrial- Nitrogen

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12
Q

The forms of P in surface water strive for chemical _____

Describe P retention by sediments

A

equilibrium

dissolved P in water –> biomass P (eg in a fish) –> fish dies and releases its P in the bottom sediments (sediment P)

(this is a cycle and it takes a very long time)

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13
Q

a whole-ecosystem experiment in the Antarctic Ocean determined that __ can be a limiting factor in the ocean

A

iron (Fe)

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14
Q

what were the effects of adding iron to the ocean?

A
  • reducing the availability of atmospheric CO2 (more goes into ocean)
  • increases ocean pollution (more dissolved CO2) and little effect on atmospheric CO2
  • this happens b/c phytoplankton produce more (removes CO2 from surface water, but that’s constantly replaced by atmospheric CO2)
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15
Q

Research at ELA in 1960s-80s looked into which nutrients are limiting. Which 3 nutrients did they look at?
Why did they do these experiments?

A

P
C
N

these experiments were in response to eutrophication of lake eerie in 1950s

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16
Q

explain the experiment that occurred at ELA Lake 227

A

Lake 227 was an oligotrophic (nutrient poor) lake, which they added P to. After the P additions, the lake quickly became nutrient rich (eutrophic)

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17
Q

Using ELA Lake 226, how did they confirm that P was what caused Lake 227 to become eutrophication?

A

Lake 226 was divided into 2
- in one half, nitrogen and carbon were added
- in the other half, nitrogen, phosphorous, and carbon were added

Only the half that contained P became eutrophic, the other half remained oligotrophic (C and N don’t have an effect)

18
Q

T/F
experiments in ELA lakes 226 and 227 caused ban P use in detergents

A

true!

19
Q

T/F
there is no clear consensus on how to address eutrophication

A

true :(

20
Q

explain top-down vs bottom-down controls on primary production

A

Top-down controls: herbivores are in control of primary production (production of grass for ex)

Bottom down controls: nutrients, light, water, etc are in control of primary production

21
Q

A lake has the following trophic cascade:

Piscivore (top predator)
Planktivore (predator)
zooplankton (herbivore)
phytoplankton (autotroph- algae)

How does the presence of the top predator decrease eutrophication?

A

Piscivore (top predator) feeds on the planktivore. So, there are fewer planktivore to feed on zooplankton, causing an increase in zooplankton.
These zooplankton feed on phytoplankton, causing a decrease in phytoplankton, meaning that there is less algae in the lake (no eutrophication!)

The opposite is true without a top predator= more phytoplankton= eutrophication

22
Q

In a eutrophic lake, the bottom becomes deoxygenated. What would be the effect on a fish species that is undergoing speciation (one species in surface waters, one in deep waters)

A

They’ll undergo reverse speciation!

The species living in the deep water will move up to access the higher oxygen waters. But, that’s where the other species is, and they will start to interbreed again. Eventually, the speciation is fully reversed and you’re left with just one species again

23
Q

a natural (____) aquatic system has:
- natural ____
- few ____ and few phytoplankton
- lots of _____

A

pristine

vegetation

nutrients

predators

24
Q

A ____ aquatic system has many stressors.
List 5

A

developed

agriculture
cottages
sport fishing
high nutrients
few predators

25
Q

T/F
a cyanobacterial bloom limits light penetration, smells bad, and is non-toxic

A

false
TOXIC!
does smell bad and does limit light penetration

26
Q

why is eutrophication predominant in the west end of Lake Eerie?

A

lots of rivers come in on this side- they bring in lots of nutrients from agricultural runoff

27
Q

T/F
1. the algal bloom of 2015 in Lake Eerie ended in 2018

  1. the middle of Lake Eerie suffers the most from oxygen depletion because it is the deepest
A
  1. false- it’s still happening :(
  2. true- surface waters have sufficient oxygen
28
Q

hypoxia occurs when water concentration is less than __ mg/L

A

2

extreme loss of oxygen

29
Q

___ ___= hypoxic areas in aquatic ecosystems, typically a consequence of pollution, eutrophication, and high rates of decomposition, that are essentially devoid of life (can’t support most organisms)

A

dead zones

extreme loss of oxygen :(

30
Q

anoxic=

A

0mg/L of oxygen- no oxygen at all!

31
Q

explain how a hypoxic zone forms

A
  1. nutrients enter the lake
  2. these nutrients cause an algal bloom
  3. these algae eventually die and sink to the bottom
  4. bacteria decompose the algae, respiring and consuming oxygen
  5. the temp. stratified water prevents the cold, dense, oxygen-depleted water at the bottom from mixing with the warmer, oxygenated upper water
32
Q

explain how a dead zone forms in the gulf of mexico (marine example)

A
  1. during the spring, warm, oxygenated freshwater from the Mississippi river pushes the colder saltwater down (cuts off contact with atmospheric oxygen)
  2. nutrients cause an algal bloom. When they die, they sink to the bottom and use up the oxygen in the deeper water as they decompose
  3. the deeper water become oxygen-deprived, and doesn’t have contact with any oxygen to replenish= becomes a dead zone (organisms avoid this zone or die in it)
  4. in the winter, the freshwater is colder, so mixing is possible and this problem doesn’t occur. But it’ll happen again in the spring
33
Q

There are over ___ dead zones across the world, mostly around ___

A

400
coasts

34
Q

The root of the dead zone problem in the gulf of mexico is:

A

the huge watershed of the Mississippi river
- tons of fertilizers used, agricultural runoff, etc- they end up in the river and then in the gulf

35
Q

T/F
dead zones can occur in both marine and freshwater

A

true

36
Q

HABs=

A

harmful algal blooms

37
Q

cyanobacteria=

A

“blue-green algae”
= a phylum of bacteria that can photosynthesize (not actually algae)

38
Q

Some cyanobacteria produce toxins called ___
- List 3 different types and what they impact

A

cyanotoxins

  1. neurotoxins- damage the brain
  2. hepatotoxins- cause liver damage
  3. dermatoxins- cause skin irritations
39
Q

_____= the most common bloom-causing cyanobacteria. Can produce both neurotoxins and microcystins (a type of ___)

A

microcystis sp.

hepatotoxins

40
Q

Nodularia sp. produces potent ____ called nodularins that can greatly harm humans

A

hepatotoxins

41
Q

what’s the most likely exposure fof all kinds of microcystins?

A

digestion (in our water, etc)

BIOL 381 (22 decks)

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