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EAS 212: The Oceans > 18. Marine Biogeochemical Cycles 1 > Flashcards

18. Marine Biogeochemical Cycles 1 Flashcards

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1
Q

T/F

All life on earth shares the same underlying mechanisms of capturing and storing energy, manufacturing proteins, & transmitting info b/w generation

A

true
- all life on earth is the same, just ‘packaged’ in different ways!

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2
Q

Pelagic environment vs benthic enviro

A

pelagic= open ocean: drifters/ swimmers live

benthic= sea bottom enviro: marine algae/ animals do not float/ spend their lives here

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3
Q

Hydrothermal vent communities were discovered in ____ and are associated with __ vents

A

1977
hot

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4
Q

What lives at hot vents? How do they produce food?

A

Archaea
Using heat and chemicals: NOT photosynthesis

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5
Q

_____ and ______ are the groups of organisms that inhabit the water column. ____ are the bottom dwellers

A

Plankton (drifters) and Nekton (swimmers)

Benthos

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6
Q

Light energy from the sun is trapped by ____ in primary producers and changed into chemical energy

A

chlorophyll

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7
Q

T/F

Photosynthesis is reversible

A

true
“remineralization” –> heat energy is released

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8
Q

What are the 3 zones of water based on light availability?

A

Euphotic zone
Dysphotic zone
Aphotic zone

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9
Q

____ is the single most important factor determining distribution of animals in the oceans

A

light

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10
Q

Euphotic zone=

A

Zone where there is sufficient light penetration to support photosynthesis
Sfc to ~100 (whatever depth all wavelengths of light penetrate to)

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11
Q

Dysphotic zone=

A

Zone that has small but measurable quantities of light
Extends from euphotic zone to the depth where light can no longer penetrate

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12
Q

Aphotic zone=

A

area of the water column with no light penetration
~1000m
no photosynthesis here

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13
Q

_____ wavelengths penetrate deepest into the water column.

Which wavelengths are absorbed first?

A

Blue= deepest

Longer wavelengths (red/ orange) are absorbed first (don’t penetrate very deep)

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14
Q

Chlorophyll is a green pigment. Which wavelengths does it absorb best? Explain how this affects the distribution of phytoplankton

Give the exception

A

Red and violet

Since very little red light penetrates past 3m, most phytoplankton stay near the sfc to absorb red light

Exception= cyanobacteria which can use blue light

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15
Q

Primary productivity is highest where? Why?

A

near the top of the euphotic zone b/c most light available for photosynthesis (inc red light)

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16
Q

Where does the max photosynthetic rate occur?

A

below the surface –> too much UV above, too little light below

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17
Q

Compensation depth=

What does this usually correspond to?
Is this fixed?

A

Depth where photosynthetic rate= respiration rate
So, net photosynthesis is zero

Usually corresponds to depth where 1% of sfc light penetrates (bottom of the euphotic zone)

Not fixed; will vary b/w locations and at diff times of day

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18
Q

Describe the oxygen and nutrient content at the surface

A

oxygen abundant due to mixing & photosynthesis

Nutrient content low b/c it’s being consumed by algae

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19
Q

At deeper depths, oxygen decreases as it’s consumed by heterotrophic organisms, producing a(n) ____ ____ _____. What are the nutrient levels at this depth?

A

Oxygen minimum layer (OML)

Nutrient level= maximum at this depth

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20
Q

The primary producers in the ocean are:

vs land

A

microscopic phytoplankton in ocean, macroscopic plants like grasses on land

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21
Q

Plankton=

A

All organisms (algae, animals, bacteria) that drift with ocean currents

planktos= wandering

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22
Q

T/F
Most of earth’s biomass consists of plankton adrift in the ocean

A

true!

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23
Q

Though 98% of marine species are bottom dwelling, the majority of the ocean’s biomass is ______

A

plankton

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24
Q

Can plankton determine their horizontal position in the water column? What about vertical?

A

Horizontal: No, can’t work against the currents
Vertical: Do have some vertical migratory ability

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25
__-__% of the ocean's biomass relies on photosynthesis for food (indirectly or directly)
95-98%
26
Ocean primary productivity= What's this measured in?
the incorporation of carbon atoms into carbohydrates by photosynthesis g of C bound into carbohydrates per square m of the ocean C/m2/yr
27
How can you measure marine primary productivity directly?
capture plankton in plankton nets
28
How can you measure marine primary productivity experimentally?
measure radioactive carbon in seawater
29
How can you measure marine primary productivity remotely?
monitor ocean color with satellites - photosynthetic phytoplankton use green pigment chlorophyll
30
Nutrients cycle from producer to consumer & back much more quickly in _____ (marine/ terrestrial) ecosystems
marine
31
Total producer biomass in the ocean is: vs Living biomass on land is:
1-2billion metric tons 600-1000 billion metric tons
32
Compare global net productivity in marine ecosystems vs global terrestrial productivity
global net productivity in marine ecosystems= 35-50 billion metric tons of C bound into carbohydrates (per yr) global terrestrial productivity is similar: 60-70 billion metric tons
33
How are plankton typically classified?
by size picoplankton to megaplankton
34
Give the 4 major groups of marine phytoplankton
Diatoms Coccolithophores Dinoflagellates Picoplankton
35
diatoms=
dominant & most productive algae; test (shells) made of silica & these tests accumulate on the seafloor
36
Coccolithophores=
small single-celled autotrophs with plates of calcium carbonate; contribute significantly to calcareous seafloor deposits
37
Dinoflagellates are marine phytoplankton that produce harmful _____ _____ - How do they make food? - They can produce ____ which are consumed by fish, and then by humans. Humans who eat this may get ________ _________ ________
algae blooms (HABs) --> red tide - mostly mixotrophic (can be autotrophic & heterotrophic: make own food & consume food) - toxins Paralytic shellfish poisoning (PSP)
38
What is picoplankton?
very small (0.2-2micrometers) plankton; extremely abundant & productive May account for 80% of photosynthetic activity in some parts of the open ocean (esp in low nutrient areas)
39
What is Prochlorococcus?
Probably the most abundant photosynthetic organism on earth! It's a picoplankton --> have a chlorophyll variant that allows it to absorb blue light at low light intensities
40
Describe the classic N-P-Z marine food web
= most basic model of a pelagic ecosystem, examining the relationship b/w quantities of Nutrients, Phytoplankton, and Zooplankton (NPZ)
41
Microbial loop=
pathway by which dissolved organic C is returned to higher trophic levels via incorporation into bacterial biomass and then coupled with the classic phytoplankton-zooplankton- nekton food chain
42
Small heterotrophic bacteria consume ___ ____ ____ that are released into the ocean by plankton
soluble organic materials
43
99% of the mass of living things is built from which 4 elements?
Carbon Oxygen Hydrogen Nitrogen
44
Macronutrients compose nearly all of the other 1% of the mass of living things (after the 4 major elements). Atoms of macronutrients combine to make what?
carbohydrates, fats, proteins, nucleic acids (DNA)
45
________ are present in living organisms in very small quantities but are necessary for life
micronutrients
46
______, not diversity is the central message of biology
unity
47
detritus=
dead remains and waste products
48
Elements/ small molecules forming the tissues of an organism may cycle rapidly in/ out of living things or they may be stored in the deep _____ for great spans of time
ocean (or earth)
49
What do the nature of biogeochemical cycles dictate? (3)
- what will live where - which organisms will be successful - ultimately what the composition of the ocean & atmosphere itself will be
50
The ______ cycle is the earth's largest cycle
carbon
51
____ is the basic building block of life on earth
carbon
52
How does carbon enter the atmosphere?
as CO2 - by the respiration of living organisms, volcanic eruptions, the burning of fossils fuels etc
53
How is CO2 fixed into organic molecules?
photosynthesis captures sunlight and use this energy to fix CO2 into organic molecules --> food or structural components
54
When an animal eats a plant, what are 3 'pathways' it can take?
1. it can be incorporated into the animal's body for growth ~45% 2. It can be respired by the animal (taken apart to harvest energy) ~45% - ultimately to atmosphere 3. It can be wasted (excreted) back into seawater as dissolved organic carbon ~10%
55
Eventually, organisms (& their shells) sink below the mixed layer in the ocean and fall to the seafloor. What happens to the C?
Most of the C in CaCO3 (shells etc) is turned into CO2 by heterotrophic bacteria before it hits the bottom. - a small amount ~1% reaches the sediments where it's buried - eventually the buried C can be weathered etc and returned to upper ocean
56
POC=
particulate organic carbon - Carbon in particulate organic material - litter of plant/ herbivore origin - detritus
57
DOC=
dissolves organic carbon - C in organic compounds (acids, sugars, etc) - serve as primary food source
58
DIC=
dissolved inorganic carbon - serves as a primary course for photosynthesis and controlling the pH
59
Dissolved carbon can pass through a small pore sized ____
filter
60
Biological pump=
the way in which material is removed from the euphotic zone to the seafloor - 'pumps' CO2 and other nutrients from the upper ocean & concentrates them in the deep ocean/ seafloor sediments
61
Do marine organisms often suffer from deficient C? Why or why not?
No - B/c of large amounts of CO2 available in the ocean & b/c atmospheric CO2 readily dissolves in seawater
62
Deficiencies to marine life are typically in which cycles? (3)
nitrogen phosphorus iron
63
Respiration _______ oxygen and photosynthesis ______ oxygen (produces/ consumes)
resp= consumes photosyn= produces
64
T/F Surface [O2] is close to equilibrium with the atmosphere
true
65
How does [O2] change with depth? Why?
decreases with depth as oxygen is consumed in respiration (more respiration deeper as light is lost) Below 1000m, [O2[ increases again because most organic matter is consumed above that level
66
Why does the deep ocean have higher [O2]?
Because rates of O2 consumption are low & there is a supply of cold, O2-rich waters from polar regions
67
Eutrophication= causes/ effects?
artificial enrichment of waters by a previously scarce nutrient causes: sewage, fertilizer, animal waste - can cause algal blooms --> extensive hypoxia causing "dead zones"
68
T/F Dead zones caused by eutrophication are associated with mouths of major rivers and spring runoffs
true
69
Can most higher order marine organisms tolerate dead zones caused by eutrophication? Impact on bottom dwellers?
No suffocates bottom dwellers
70
Describe 2 dead zones that currently exist
1. Gulf of Mexico dead zone: 2nd largest - runoff of nutrients, esp nitrates= algal blooms 2. North East Subarctic Pacific Ocean - off coast of Van island - expansion over last 5 decades
71

EAS 212: The Oceans (18 decks)

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