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Biology 1108 > Unit 2 - Food Webs & Trophic Levels, Apex Predators, & Marine Pollution > Flashcards

Unit 2 - Food Webs & Trophic Levels, Apex Predators, & Marine Pollution Flashcards

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1
Q

definition: theory that suggests choosing prey that maximize net energy GAIN

A

optimal foraging theory

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2
Q

What 2 prey of otter have very low, constant frequencies in the habitat, which explains why they are less frequent in sea otters’ diet?

A

cancer crab & red abalone

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3
Q

When there was a drop of Red Sea urchins making up 8% to 1% of the environment, what happened to the frequency of kelp crab in diet?

A

went up

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4
Q

Kelp crab are ______ frequent in the habitat compared to Red Sea urchin, cancer crab, and red abalone.

A

very

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5
Q

Sea otters eat everything at a higher rate than in environment except what?

A

kelp crabs

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6
Q

Even though they have a high frequency, sea otters tend to ignore ______.

A

kelp crabs

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7
Q

Urchin frequency in diet and ecosystem _____ significantly.

A

drops

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8
Q

What two species do otters always prefer, but they are rare? What does this lead to?

A

abalone and cancer crab; they in turn eat a lot of urchins until they become rare

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9
Q

Once urchin population become rare, who do sea otters have to turn to?

A

clam & kelp crab

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10
Q

definition: switching to the next best prey item when a preferred item becomes rare (energetically more costly) (ex: cancer crabs > abalone > urchins > kelp crabs

A

prey switching

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11
Q

What do arrows represent in a food web?

A

energy flowing through a system

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12
Q

definition: where an organism is in the food chain / how far it is energetically removed from photosynthesis

A

trophic level

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13
Q

What are the producers in the Kelp forest ecosystem?

A

kelp, seaweed, and phytoplankton (plant plankton)

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14
Q

Where does the energy in a food web come from to begin with?

A

the sun–solar energy

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15
Q

Producers are on the _____ level of a food chain.

A

lowest

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16
Q

Primary consumers eat ______.

A

producers

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17
Q

What are some unique characteristics of phytoplankton?

A

-“Plant plankton”
-producers
-photosynthetic microorganisms
-microscopic algae
-contribute 1/2 of the world’s Oxygen

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18
Q

What are some unique characteristics of zooplankton?

A

-animal plankton or planktonic invertebrates
-eat phytoplankton or other zooplankton
-can be primary or secondary consumers

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19
Q

Energy loss (trophic efficiency):
-each step up in trophic level decreases energy by how much?

A

90%

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20
Q

Only ____% of energy is conserved as you go up a trophic level.

A

10

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21
Q

If there is less sun, what is the effect on higher trophic levels?

A

less upper-level organisms because there will be less energy reaching those upper levels

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22
Q

With more _____ energy at the bottom, we can support a lot more life & biodiversity at the top.

A

solar

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23
Q

Why is so much of the energy (biomass) lost as you go up trophic levels?

A

when converting energy forms, some energy is lost as heat/entropy

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24
Q

____ law of thermodynamics: energy can be transferred and transformed, but not created or destroyed

A

first

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25
Q

_____ law of thermodynamics: every energy transfer or transformation increases the entropy (disorder) of the universe

A

second

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26
Q

Where does all the biomass (energy stored in bonds) go when a caterpillar eats a leaf?

A

50% is eliminated in feces
35% is used for cellular respiration
15% is used for growth

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27
Q

Is all the energy incorporated by plants through photosynthesis available to the caterpillar?

A

No, only 10% of the energy is available to the caterpillar

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28
Q

What % of the plants eaten by a caterpillar would be useful to a bird that eats the caterpillar?

A

1%

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29
Q

How much % of calories in grain grown for livestock is assimilated by humans?

A

1%

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30
Q

How much % of crop calories are consumed by humans?

A

27%

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31
Q

Is eating meat or crops more efficient?

A

crops

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32
Q

What are two reasons that eating meat is better for the planet?

A

(1) reduced carbon emissions
(2) less land use

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33
Q

Does a veggie or meat burger require more energy to produce?

A

meat (animals eat more complex food so they need more energy to synthesize it)

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34
Q

When were otters hunted to near extinction in the West?

A

in the 1800s

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35
Q

After extinction in the early 1900s, when was the first otter population spotted in Big Sur CA?

A

1938

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36
Q

With sea otters, what does the ecosystem look like?

A

kelp forest

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37
Q

Without sea otters, what does the ecosystem look like?

A

urchin barren

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38
Q

What species on the normal kelp forest food web decreases without sea otters being present? increase?

A

extinction: abalones, larger crabs, larger fishes and octopus, sessile invertebrates, small herbivorous fishes & invertebrates, smaller predatory fishes and invertebrates
increase: sea urchins
decrease: drift algae & dead animals, kelp, planktonic invertebrates

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39
Q

What was the timeline for the switch from kelp forest to urchin barren?

A

1800s–> early 1900s

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40
Q

What are some unique characteristics of sea urchins?

A

-invertebrates
-related to sea stars (echinoderms)
-mostly herbivores
-spines for protection
-kelp is primary food source when available

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41
Q

definition: when changes at ONE trophic level have dramatic effects throughout a food web

A

trophic cascade

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42
Q

definition: an organism with an outsized influence relative to its abundance

A

keystone species

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43
Q

What is usually thought of as the “collapse” of an ecosystem?

A

trophic cascade

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44
Q

What makes sea otters a keystone species?

A

-its role as a top predator
-maintains healthy kelp forests and seagrass beds

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45
Q

Do keystone species have to also be predators?

A

no

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46
Q

What are some examples of keystone species?

A

wolves, bears, starfish, & elephants

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47
Q

In kelp forests, what organism is the keystone species?

A

sea otters

48
Q

definition: an organism/predator at the top of the food chain

A

apex predator

49
Q

Are sea otters apex predators?

A

yes

50
Q

Even though kelp forests are diverse with high stability, what caused them to topple so fast?

A

removal of a keystone species

51
Q

Why is a kelp forest preferable to an urchin barren?

A

-carbon sequestration
-vertical complexity
-biodiversity
-ecosystem stability
-economically important juvenile fish habitat (fish have better protection from predators in Kelp forest)

52
Q

What is the process called where phytoplankton, which live on the warm, light-filled surface, suck CO2 out of the atmosphere for food?

A

carbon sequestration

53
Q

With sea otters, what are the levels of kelp and urchins like?

A

kelp: very high
urchins: low

54
Q

Without sea otters, what are the levels of kelp and urchins like?

A

kelp: very low
urchins: extremely high

55
Q

Is there a continuum that exists between no kelp and tons of kelp?

A

not really

56
Q

Urchin barren and kelp forest are examples of alternative _____ ecosystems?

A

stable

57
Q

What concept states that ecosystems can have multiple stable modes that are difficult to transition out of?

A

alternative stable states

58
Q

What are examples of alternative stable states?

A

-savannah and forest
-coral reef and algae

59
Q

definition: ______ control: producer’s populations are limited by ABIOTIC factors (nutrients, climate disturbance)

A

bottom-up

60
Q

definition: _______ control: producer’s populations are kept in check by herbivory & predators control herbivore populations

A

top-down

61
Q

What type of control do kelp forests have? Why?

A

top down because urchins exhibit pressure on kelp (herbivory)

62
Q

In the Sonoran desert, what type controls plant populations?

A

bottom-up –> plants are mostly likely dependent on the limiting resource of water in their soil

63
Q

In what year do otter reintroductions start? And what happens to urchin barren?

A

1970s; reversal of alternative stable state back to kelp forest

64
Q

What happens when a top predator is reintroduced like sea otters?

A

the population will grow and then stabilize at its maximum capacity in the 1980s and 90s along the CA coast

65
Q

What happened after a century of recovery with sea otters?

A

they began disappearing again (especially in Alaska)

66
Q

What was the main reason for otter reduction the 2nd time?

A

orca/killer whales

67
Q

What was the main reason for otter reduction the first time?

A

overhunting

68
Q

What demonstrated that the otter’s keystone role has been reduced or eliminated?

A

elevated sea urchin density and consequent deforestation of kelp beds

69
Q

What are some pieces of evidence that implicate orcas as the reason for the decline in otters?

A

-decline of great whales from whaling, a common prey of killer whales, forced them to turn to other Marine animals
-sea otters are easy to catch and eat & only a small number of orcas are needed to greatly decreases sea otter populations
-no washed up sea otters
-no relocation of sea otters
-increased orca attack sightings
-only otter loss in the open ocean, not in protected lagoons

70
Q

What is the preferred prey list for killer whales?

A

great whales–>harbor seals–>stellar sea lions–>sea otters

71
Q

Why would orcas all of the sudden start eating more otters?

A

their preferred prey declined dramatically, so they prey switch

72
Q

What led from kelp–> urchin barren from pre-19th century–> 19th century?

A

hunting of otters

73
Q

When did otters recover after being hunted?

A

in mid to late 1950s

74
Q

What led from kelp–> urchin barren again from the 1990s–> 2010s?

A

killer whales

75
Q

What shows the structure–>function of ecosystems?

A

-number of trophic levels (structure) is related to the function of an ecosystem:
-3 trophic levels: kelp
-4 trophic levels (addition of orcas): no kelp
-5 trophic levels (to get rid of orcas): kelp

76
Q

In an uncolonized habitat, what does the rate of colonization depend on?

A

mobility

77
Q

In recently colonized sub-populations, what is the growth rate like?

A

very high

78
Q

In long established subpopulations at carrying capacity, what is growth rate like?

A

population is regulated at local scales

79
Q

When was direct evidence of orca responsibility released and how?

A

in 2020; a beached orca was found with 6 recently eaten otters in its stomach

80
Q

What are the 3 main things involved in non-Carbon pollution?

A

(1) Heavy metals
(2) persistent organic pollutants (PCBs)
(3) nutrients (N & P)

81
Q

Which pollutants (heavy metals) tend to accumulate in organisms over time?

A

Mercury (Hg) and Lead (Pb)

82
Q

Which pollutants (persistent organic pollutants POP) tend to accumulate in organisms over time?

A

PFAs, PCBs, DDT

83
Q

Where are POPs stored in the body? How are they passed on to offspring?

A

fatty tissue; through blood and breastmilk (particularly a big problem in mammals)

84
Q

In what two ways can toxin accumulation cause excess mortality?

A

(1) trophic level
(2) age

85
Q

definition: toxin build up in an individual as it AGES (only one species involved)

A

bioaccumulation

86
Q

definition: toxin concentrations increase as you move up through TROPHIC LEVELS (different species involved)

A

biomagnification

87
Q

Why does a young fish have less toxins than an older fish?

A

it hasn’t had as many chances to accumulate toxins; hasn’t ate as much other organisms yet

88
Q

Can both bioaccumulation and magnification happen?

A

yes

89
Q

Why do top predators of the food chains have more toxins than producers?

A

because the contaminants increase in concentration up the food chain

90
Q

What are 3 examples of persistent chemicals that bioaccumulate or magnify?

A

mercury, lead, and PCBs

91
Q

What do all of the fish that should be avoided during pregnancy because they have high mercury content have in common?

A

they are all top predators and higher up on food chain

92
Q

What has been happening to orcas?

A

-increased juvenile mortality
-some populations are plummeting
-overfishing
-biomagnification
-whaling

93
Q

Why do transient killer whales experience more juvenile mortality than resident pods?

A

they are higher up on food chain; exist at a higher trophic level = more toxins = more harm to offspring

94
Q

What nutrients and fertilizers runoff from many sources into water? What will this do to an organism in the water?

A

Nitrogen and phosphorus; cause algal blooms and plant growth

95
Q

definition: a process that results in EXCESS plant growth and eventually leads to the death & loss of animal life

A

eutrophication

96
Q

Steps of eutrophication:
(1) _____ of excess nutrients from yards and farms
(2) _____ of nutrients causes aquatic plants and algae to ____
(3) ____ is released
(4) resources become ______ and algae reach _____ ______
(5) algae begin to ____ and _______
(6) ______ is consumed
(7) hypoxia or ______
(8) animals ____ or ____

A

runoff
pulse
oxygen
limited; carrying capacity
die; decompose
oxygen
anoxia
leave; die

97
Q

In the decomposition process, bacteria will use up all the available _______.

A

Oxygen

98
Q

What are some eutrophication solutions?

A

-reduction of fertilizer
-erosion control (no/low till agriculture)
-riparian river buffers–> keeping more vegetation surrounding waterways

99
Q

What leads to the dead zone in the Gulf of Mexico?

A

the Mississippi River collecting nutrients and water from farms all over the middle of the US (eutrophication)

100
Q

What is ocean acidification a result of?

A

increasing atmospheric CO2 (not climate change directly)

101
Q

Ocean is a CO2 ______.

A

sink

102
Q

What is the evil twin of global warming?

A

ocean acidification

103
Q

Carbon dioxide from the atmosphere and water lead to the formation of what?

A

carbonic acid

104
Q

What do organisms use to build their shells?

A

Calcium Carbonate

105
Q

What do abundant healthy corals, mollusks, and other marine calcifies want?

A

carbonate ions for their shells

106
Q

Why does carbonate level decrease with ocean acidification?

A

more carbonate molecules become bound up to carbonic acid molecules

107
Q

What happens to the pH of water with ocean acidifcation?

A

drops

108
Q

Small reductions in pH levels make it _____ for organisms to form Ca shells (shells become thinner & more brittle).

A

harder

109
Q

What will happen to species is we remove plankton?

A

bottom-up trophic cascade

110
Q

A collapse in plankton population would echo _____ the food chain.

A

up

111
Q

What are the 2 main steps in ocean acidification?

A

(1) Ocean absorbs CO2 from the atmosphere, creating carbonic acid in waters.
(2) Carbonic acid (steals) carbonate needed by some marine organisms to build their shells.

112
Q

What are some common shell building organisms?

A

coral, clams, urchins, mussels

113
Q

What are 3 main steps in ocean acidification?

A

(1) CO2 dissolves in water releasing Hydrogen ions (H+)
(2) H+ and Calcium (Ca2+) compete for carbonate
(3) the excess H+ hogs the carbonate

114
Q

How is it possible to have kelp forests without sea otters?

A

other keystone species such as sea stars (SUNFLOWER stars specifically)

115
Q

Intertidal kelp ecosystems maintained by sunflower/sea stars are not able to support what?

A

otters

116
Q

What were the main 2 things contributing to sea star wasting syndrome?

A

(1) climate stress
(2) bacteria

Biology 1108 (12 decks)

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