Segar: Foundations Of Life In The Oceans (Incomplete)

Front 1

What are two characteristics of the ocean that make it ideal for life?

Back 1

It is quite uniform, and all essential elements are present as dissolved compounds and ions.

Front 2

What are the three domains?

Back 2

bacteria, archaea and eukarya

Front 3

What do bacteria and archaea comprise?

Back 3

prokaryotes

Front 4

What are the four kingdoms of eukarya?

Back 4

Protista, Fungi, Plantae, and Animalia

Front 5

How are individual species labeled?

Back 5

Genus species (in italics)

Front 6

What is the most important use of organic molecules to life?

Back 6

provide energy for biochemical processes

Front 7

What process(es) do living organisms use for energy?

Back 7

All use respiration.

Front 8

What do autotrophs do?

Back 8

create their own food from inorganic compounds, employing an external source of energy

Front 9

What is the process of converting inorganic compounds into organic matter called?

Back 9

primary production

Front 10

What do heterotrophs do?

Back 10

obtain organic matter as food

Front 11

What are the two methods of primary production?

Back 11

photosynthesis and chemosynthesis

Front 12

What are the inputs to photosynthesis?

Back 12

(sun)light, dissolved carbon dioxide and water

Front 13

What nutrients are necessary for photosynthesis?

Back 13

nitrogen, phosphorus, magnesium and sulfur

Front 14

Where can chemosynthesis get its energy?

Back 14

H2S, metal, H2, or CH4 oxidation

Front 15

Where can chemosynthesis not occur?

Back 15

where there is oxygen

Front 16

Where is chemosynthesis most common in the oceans?

Back 16

near hydrothermal vents found on ridges and volcanoes

Front 17

Where can chemosynthesis happen?

Back 17

near hydrothermal vents, sediment seeps and vents, where groundwater reaches the ocean, salt marshes, swamps, and fjord bottom waters

Front 18

What do heterotrophs include?

Back 18

all animals and most bacteria and fungi

Front 19

What nutritional modes do animals utilize?

Back 19

herbivores (eat plants), carnivores (eat animals), omnivores (eat both), and detritivores (eat detritus)

Front 20

What do decomposers eat?

Back 20

organic particles and dissolved organic compounds

Front 21

What are the two paths organic molecules and energy follow in the ocean?

Back 21

the traditional food chain and the microbial loop

Front 22

What does the microbial loop involve?

Back 22

release of organic molecules by autotrophs or zooplankton which is later consumed by bacteria and archaea

Front 23

What determines the depth that light reaches in the ocean?

Back 23

turbidity

Front 24

Where is turbidity the highest?

Back 24

in shallow coastal waters where waves churn up bottom sediments

Front 25

What is the photic zone?

Back 25

There are actually two different definitions: (1)where sunlight intensity is more than 1% of the surface intensity and (2) where photosynthesis rates exceed respiration rates.

Front 26

Where do autotrophs in the ocean get their nutrients?

Back 26

from the surrounding waters

Front 27

Where do most marine algae live?

Back 27

in the water column, not attached to the seafloor

Front 28

How do marine macroalgae stay afloat?

Back 28

They have pockets of gas or air that float

Front 29

How big are most phytoplankton?

Back 29

one eukaryotic cell

Front 30

How do phytoplankton in general stay afloat?

Back 30

They rely on water's high viscosity and wave and current turbulence to keep them afloat.

Front 31

How do diatoms stay afloat?

Back 31

Diatoms store food in oils to increase buoyancy, have spines or form colonies.

Front 32

How do dinoflagellates stay afloat?

Back 32

They have flagella for limited motility.

Front 33

What factors affect the intensity of light at a specific depth?

Back 33

the intensity reaching the surface, the angle of incidence, and the turbidity of the water

Front 34

How deep does the photic zone often extend?

Back 34

100 meters in the open ocean and 5-10 meters in coastal waters

Front 35

Does respiration or photosynthesis vary more as one descends or ascends?

Back 35

Photosynthesis varies more.

Front 36

What is the lower boundary of the photic zone?

Back 36

the compensation depth, where photosynthesis and respiration rates are equal and the depth that 1% of the surface light reaches

Front 37

What are the regions not in the photic zone?

Back 37

the aphotic zone

Front 38

Why is the region of maximum photosynthesis a little below the surface of the ocean?

Back 38

UV light interferes with photosynthesis but is absorbed in the upper layers of the ocean.

Front 39

Which elements do photosynthesizers need that are present in high concentrations in seawater?

Back 39

carbon, hydrogen, oxygen, magnesium and sulfur

Front 40

Which elements do photosynthesizers need that are present in low concentrations in seawater?

Back 40

nitrogen, phosphorus, iron, zinc, cobalt, and sometimes silicon

Front 41

What processes remove nutrients from the seawater?

Back 41

uptake by marine organisms and adsorption onto lithogenous particles

Front 42

What is a system in which primary productivity is limited by nutrient levels called?

Back 42

nutrient-limited

Front 43

What are possible limiting nutrients?

Back 43

nitrate, nitrite, ammonia/um, phosphate, iron and silicate

Front 44

How can photosynthesizers increase the rate of diffusion of molecules across their membranes?

Back 44

increase their surface area

Front 45

How can photosynthesizers decrease their nutrient requirements?

Back 45

in general, reduce their volume

Front 46

Why are most marine autotrophs small?

Back 46

to absorb the most nutrients relative to their needs

Front 47

What are two ways marine organisms cope with nutrient deficiencies?

Back 47

by being small and storing extra nutrients when they are not limiting

Front 48

What is involved in nutrient recycling?

Back 48

decomposers breaking down fecal pellets

Front 49

What are the relative rates of nutrient recycling?

Back 49

phosphorus is fastest, nitrogen in between, and iron and silicon slowest

Front 50

How is phosphorus recycled so rapidly?

Back 50

60% of it is excreted by zooplankton

Front 51

What form of nitrogen is released from amino acid degradation?

Back 51

ammonium

Front 52

What forms of nitrogen are excreted by animals?

Back 52

urea and uric acid, which bacteria degrade to ammonium

Front 53

What four forms of nitrogen are found in the ocean?

Back 53

ammonium, nitrite, nitrate, and dinitrogen

Front 54

What convert ammonium in the oceans to nitrite and nitrate?

Back 54

bacteria

Front 55

What complicates nitrogen's biogeochemical cycle?

Back 55

exchange of N2 between the atmosphere and ocean and nitrogen-fixing and denitrifying bacteria and archaea

Front 56

Where is nitrogen fixation important?

Back 56

in nutrient-poor environments like the centers of subtropical gyres and coral reefs

Front 57

Why does phosphorus not become the limiting nutrient too often in nutrient-deficient environments?

Back 57

Only a small fraction is not put back into solution.

Front 58

What is silica used for in the ocean?

Back 58

shells/skeletons of marine organisms, such as the frustules of diatoms

Front 59

How is silica recycled?

Back 59

It first must dissolve chemically, which happens very slowly

Front 60

How can silica become a limiting nutrient?

Back 60

Once it is depleted, it takes a long time to dissolve and become available again.

Front 61

What effects can silica being the limiting nutrient have?

Back 61

It can change the dominant species in the area, because only some organisms have silica hard parts.

Front 62

When does silica typically become a limiting nutrient?

Back 62

during diatom blooms

Front 63

How does iron move in the ocean?

Back 63

It enters via runoff and airborned dust, then sinks in the ocean to the bottom.

Front 64

Where (theoretically) could iron be the limiting nutrient in photosynthesis?

Back 64

where river and air inputs from continents are low

Front 65

Where (specifically) is iron the limiting nutrient in photosynthesis?

Back 65

the sub-Arctic Pacific Ocean, the equatorial Pacific Ocean, and the Southern Ocean

Front 66

Why is nutrient upwelling necessary?

Back 66

Large quantities of most nutrients are released from the photic zone and sink below that zone before dissolving in the water.

Front 67

What are the two ways nutrients go from the photic zone to the aphotic zone?

Back 67

Fecal pellets sink and zooplankton migrate vertically.

Front 68

What eat phytoplankton?

Back 68

grazers, herbivores or omnivores that are either small zooplankton or much larger than phytoplankton

Front 69

How do zooplankton migrate vertically?

Back 69

Diurnal migration: They ascend at night to feed and descend during the day.

Front 70

Why do zooplankton migrate vertically?

Back 70

probably so they can avoid being seen, only entering the photic zone at night

Front 71

What mixes the mixed layer?

Back 71

winds and waves

Front 72

What forms the border between the mixed layer and the deep layer?

Back 72

the thermocline, with the density difference of the pycnocline

Front 73

In general, where do the nutrients end up?

Back 73

in deep water

Front 74

Where are nutrient concentrations usually the highest and primarily why?

Back 74

just below the thermocline layer in deep water, because it is the "oldest" water, having steadily migrated upward

Front 75

What secondary factors make nutrients the most concentrated just below the thermocline layer?

Back 75

Bacterial decomposition is inhibited by low temperature and high pressure, most organic matter does not reach the ocean floor before being dissolved, and vertically migrating animals do not go very deep.

Front 76

What limits primary productivity throughout the oceans?

Back 76

nutrients

Front 77

What areas of the ocean experience the greatest primary productivity?

Back 77

coastal upwelling regions, shallow mixed areas, and off the mouths of rivers

Front 78

What are trophic levels?

Back 78

steps in a food chain

Front 79

What percent of food consumed at each trophic level is used for growth?

Back 79

1% to 40%, with an average of 10%

Front 80

For humans, what animals should we eat in order to put the least strain on the environment?

Back 80

those closer to the bottom of the food chain, the lower trophic levels

Front 81

What are intertangled food chains collectively called?

Back 81

food webs

Front 82

What complicates labelling food webs with trophic levels?

Back 82

omnivores which eat from multiple trophic levels and detritivores

Front 83

Where are pelagic animals most abundant?

Back 83

where primary productivity is the highest

Front 84

Where are benthic animals most abundant?

Back 84

where primary productivity in the above water layers is the highest

Front 85

What determines the phytoplankton biomass (standing stock)?

Back 85

phytoplankton growth and reproduction rates versus consumption rate

Front 86

How does zooplankton biomass vary?

Back 86

It varies in line with phytoplankton biomass but lags behind by days or weeks.

Front 87

How can satellites measure phytoplankton biomass?

Back 87

by detecting chlorophyll concentrations

Front 88

What are the most productive parts of the ocean?

Back 88

coastal regions on the west sides of continents, where there is upwelling

Front 89

What parts of the open ocean are the most productive?

Back 89

high-latitude regions and the equatorial upwelling band of the east Pacific

Front 90

Why does the Southern Ocean have high primary productivity?

Back 90

because of upwelling at the Antarctic Divergence

Front 91

Why do the North Pacific and North Atlantic have high primary productivity?

Back 91

because surface waters are cool, and westerly winds and extratropical cyclones mess up the pyncocline and get nutrients back to the surface

Front 92

Where is primary productivity the lowest and why?

Back 92

the interiors of the subtropical gyres in each ocean because they don't have any nutrients from runoff, rain, or upwelling

Front 93

What processes determine the amount of oxygen dissolved in the ocean?

Back 93

photosynthesis, respiration, and exchanges between the atmosphere and ocean

Front 94

What are dissolved oxygen levels in the upper few meters of the ocean?

Back 94

saturated, because exchange with the atmosphere happens almost continuously

Front 95

What are dissolved oxygen levels in the photic zone?

Back 95

supersaturated, because photosynthesis produces more oxygen

Front 96

What happens to the oxygen produced by photosynthesis?

Back 96

Much of it is released into the atmosphere, contributing more to atmospheric oxygen levels than land plants do.

Front 97

Why is there no carbon dioxide concentration minimum in the photic zone like there is an oxygen concentration maximum?

Back 97

the carbon dioxide concentration is too high

Front 98

How much carbon dioxide released from human activity since the Industrial Revolution has entered the oceans?

Back 98

half

Front 99

What happens to carbon dioxide and oxygen levels at depth?

Back 99

Respiration happens, increasing carbon dioxide and decreasing oxygen levels.

Front 100

Where can oxygen be depleted?

Back 100

where the residence time of deep water is extremely long and/or where primary productivity is extremely high

Front 101

What are two examples of locations where oxygen can be depleted?

Back 101

the Baltic Sea, which is shallow and has a bunch of anthropogenic nutrient input, and fjords, which have a long residence time

Front 102

What do bacteria do in anoxic water?

Back 102

reduce nitrate to ammonium and sulfate to sulfide

Front 103

What problem can anoxic waters cause?

Back 103

The sulfides made by bacteria are toxic and can sometimes mix into productive regions.

Front 104

What are the results of anoxia in the past?

Back 104

Detritus is not decomposed so it is incorporated into sediments, diagenetically becoming oil and gas.