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Hilary Term 1 > Climate and Life on Earth: Marine ecology 1 > Flashcards

Climate and Life on Earth: Marine ecology 1 Flashcards

1
Q

Describe the global ocean

A

Earth’s largest habitat

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2
Q

List some oceans

A
  • Pacific Ocean
  • Gulf of California
  • Gulf of Mexico
  • Hudson Bay
  • Caribbean Sea
  • Atlantic Ocean
  • Mediterranean Sea
  • Southern Ocean
  • Red Sea
  • Persian Gulf
  • Caspian Sea
  • Black Sea
  • Indian Ocean
  • Arctic Ocean
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3
Q

Describe the structural features of the global ocean

A
  • continental shelf
  • continental slope
  • oceanic trench
  • abyssal plain
  • mid-ocean ridge
  • seamount
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4
Q

seamount

A

remains of dead volcanoes

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5
Q

mid-ocean ridge

A

volcanically active areas that can include deep-sea vents

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6
Q

Describe oxygen in water and air

A
  • 40 times less oxygen in a litre of water than in a litre of air
  • diffuses around 1000 times more slowly
  • creates an oxygen minimum zone where respiration exceeds photosynthesis and diffusion from the air
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7
Q

Describe the establishment of a thermocline

A
  • in the tropics and in summer at temperate latitudes a thermocline is established
  • because warm water is less dense, it prevents vertical mixing and leads to nutrient depletion in surface waters
  • in the tropics the thermocline is a permanent feature
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8
Q

List the light zones of the global ocean

A
  • euphotic
  • dysphotic
  • aphotic
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9
Q

Describe the euphotic zone

A
  • above 200m
  • sunlight rarely penetrates beyond
  • tuna
  • aka sunlight zone
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10
Q

Describe the dysphotic zone

A
  • above 1000m
  • sunlight decreases rapidly with depth
  • photosynthesis impossible
  • shrimp, swordfish, hatchet fish
  • aka twilight zone
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11
Q

Describe the aphotic zone

A
  • lower than 1000m
  • sunlight does not penetrate at all
  • angler fish, giant squid, tripod fish
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12
Q

Where does most photosynthesis occur vertically speaking in the global ocean?

A

top 50m

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13
Q

Describe light penetration in the global ocean

A
  • blue and green light penetrates much better than either red or violet wavelengths
  • coastal waters are generally more turbid, so light attenuates more rapidly
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14
Q

Describe deep-sea fish

A

eyes which area adapted to see bioluminescence.

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15
Q

How far can violet light penetrate in the open ocean?

A

100m

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16
Q

How far can blue-green light penetrate in the open ocean

A

200m

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17
Q

How far can red light penetrate in the open ocean?

A

25m

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18
Q

How far can violet light penetrate in the coastal waters?

A

<10m

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19
Q

How far can blue-green light penetrate in coastal waters

A

50m

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20
Q

How far can red light penetrate in coastal waters?

A

15m

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21
Q

Roughly 1/3rd of the CO2 produced by humans since the industrial revolution has been

A

absorbed by the oceans

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22
Q

Describe a time series of carbon dioxide and ocean pH at Mauna Loa, Hawaii since 1955

A
  • atmospheric CO2 increasing from 320ppmv to 400ppmv
  • seawater pCO2 increasing from 320muatm to 380muatm
  • seawater pH decreasing from 8.13 to 8.05
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23
Q

… current emissions continue to be absorbed by the oceans

A

1/2

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24
Q

Describe carbonate removal in the global ocean

A
  • hydrogen ions react with existing carbonate ions in the ocean, forming bicarbonate
  • poses problems for organisms with skeletons made from calcium carbonate
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25
Q

List some organisms with skeletons made of calcium carbonate

A

corals

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26
Q

Describe organisms that have skeletons made of calcium carbonate

A
  • rely on carbonate being saturated
  • as the ocean acidifies, their skeletons start to dissolve
  • at a pH <7.5, this becomes critical
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27
Q

Surface currents

A

redistribute thermal energy

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28
Q

Describe surface currents

A
  • rapid timescales
  • driven by wind
  • enormously important to Europe, as the NA drift brings warmer waters to us and prevents the freezing of the N Atlantic
  • gyres have static centres – e.g. Sargasso Sea in Atlantic and the Great Pacific garbage patch.
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29
Q

List some surface currents

A
  • Greenland current
  • Labrador current
  • North Pacific drift
  • Gulf Stream
  • California current
  • north equatorial current
  • south equatorial current
  • Peru current
  • South Pacific current
  • Benguela
  • canary current
  • North Atlantic drift
  • agunas
  • west Australian current
  • antarctic circumpolar current
  • east Australian current
  • Kuroshio current
  • Kamchatka current
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30
Q

Great Ocean Conveyor belt

A
  • redistributes nutrients
  • much slower-moving but moves enormous volumes of water
  • takes 100 years to move water N to S under the Atlantic Ocean. - thermohaline circulation
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31
Q

Describe thermohaline circulation

A

driven by differences in salinity and hence buoyancy, not by winds

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32
Q

How does the Great Ocean Conveyor Belt work?

A
  • cold, high salinity seawater sinks
  • warm shallow (surface) currents
  • cold deep currents
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33
Q

Describe carbon fixation in the global ocean

A

50 billion tonnes per year

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34
Q

Describe some producers in the open ocean

A
  • bacterioplankton (30 – 50%)
  • phytoplankton
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35
Q

Describe bacterioplankton

A
  • cyanobacteria
  • e.g. Prochlorococcus
36
Q

Describe phytoplankton

A
  • diatoms
  • dinoflagellates
  • coccolithophores
37
Q

Describe diatoms

A

skeletons made from silica

38
Q

Describe dinoflagellates

A

2 flagellae

39
Q

Describe coccolithophores

A

calcium carbonate skeleton

40
Q

Define deep subsurface

A

marine subseafloor sediment and the oceanic crust, as well as the terrestrial substratum deeper than 8 m, excluding soil

41
Q

Describe marine vs terrestrial biomass in Gt C

A
  • marine = 6
  • deep subsurface = 70
  • terrestrial = 470
42
Q

Marine ecosystems are characterised by (relative to terrestrial and deep subsurface)

A
  • few fungi
  • lots of protists
  • lots of animals
  • few bacteria and archaea
43
Q

archaeplastida

A

red and green algae

44
Q

List some marine protists

A
  • phytoplankton
  • brown algae (e.g. kelps)
45
Q

Describe marine animal biomass

A

dominated by fish and crustaceans

46
Q

Break down marine biomass in Gt C

A
  • protists: 2
  • animals: 2
  • bacteria: 1.5
  • plants: 0.5
  • fungi: 0.3
  • archaea: 0.3
  • viruses: 0.03
47
Q

List some marine consumers in order of biomass (Gt C)

A
  • animals
  • protists
  • bacteria
  • archaea
  • fungi
48
Q

List some marine producers in order of biomass (Gt C)

A
  • protists and plants
  • bacteria
49
Q

Describe food webs in the open oceans

A
  • vary dramatically
50
Q

Describe small zooplankton

A
  • excrete tiny faecal pellets
  • forms POM
  • nutrients are rapidly returned by heterotrophic bacteria
  • vertical movement during the 24-hour cycle ‘pumps’ carbon to the depths
51
Q

Describe the microbial loop

A
  • hugely important for recycling DOM
  • massive, due to prevalence of viruses in ocean (10 million per millilitre of seawater)
52
Q

Describe upwellings

A

support large phytoplankton (e.g. large diatoms) can be grazed directly by small fish, leading to massive fish biomass (e.g. anchoveta)

53
Q

POM

A
  • particulate organic matter
  • sinks
54
Q

DOM

A

dissolved organic matter

55
Q

What limits primary production in the open ocean?

A

light in temperate and polar regions

56
Q

Describe temperature latitudes

A
  • high productivity
  • major boom in spring
  • smaller boom in autumn
57
Q

North polar peaks in

A

July

58
Q

Upwellings of nutrient-rich water can create

A
  • hotspots of high productivity in coastal waters
  • common along the W coasts of continents: e.g. in California, Chile, Peru
59
Q

Describe the effects of strong vertical mixing and the lack of a thermocline in winter

A

temperate and polar waters are nutrient-rich

60
Q

Describe the effect of the permanent thermocline in the tropical oceans

A

prevents vertical mixing and the return of nutrients to the euphotic zone

61
Q

Describe the Peruvian anchoveta

A

most heavily exploited fish in the world.

62
Q

Describe the coastal ocean at mid-latitudes

A
  • roughly 60% of the human population (4Bn people) live within 100 km of the coast.
  • coastal seas lie above the continental shelf
  • highly productive because of strong vertical mixing (especially the W coasts of continents)
  • heavily exploited and heavily polluted
  • oil spills are a constant threat
63
Q

Describe the pollution of the coastal ocean

A

agricultural run-off has created enormous dead zones that expand every year.

64
Q

… of coastal fisheries are responsible for nearly … of the world’s wild-caught seafood

A

40%, 40%

65
Q

Describe the kelp forest

A
  • major temperate coastal ecosystem
  • economically important
  • directly harvested
  • supports important fish and shellfish
66
Q

Describe mid-latitude kelp forests

A
  • abundant
  • support a high diversity of life
  • ecologically unstable
  • sensitive to over-harvesting of key animals
67
Q

Describe kelp

A
  • multicellular brown algae
  • often annual
  • no true vascular system
  • differentiation into multiple cell types
  • can be highly productive
  • support enormous biodiversity (30 to 70 species can live just within a single holdfast)
  • significant 3D structure
  • ecosystem engineer
  • nurseries for commercially important fish species
  • very high C:N ratio
  • chemical compounds deter grazers
68
Q

List some kelp genera

A
  • Laminaria
  • Macrocystis
  • Nereocystis
  • Lessonia
  • Ecklonia
69
Q

Which are the dominant kelp genera?

A
  • Laminaria
  • Macrocystis
70
Q

Describe the multiple cell types of kelp

A
  • holdfast
  • stipe
  • blades
71
Q

Describe Macrocystis

A
  • can grow up to 30cm/day
  • reach a height of 30 m
  • dense underwater forest.
72
Q

Describe kelp stipe

A
  • supports many epiphytes
  • e.g. Phycodrys rubens.
73
Q

Phycodrys rubens

A

red alga

74
Q

Describe red algal communities

A
  • flourish under the kelp forest
  • 40-180 spp around the UK
  • support large numbers of invertebrates
75
Q

List some of the invertebrates supported by red algal communities

A
  • brittle stars
  • anemones
  • crabs
  • jellyfish
76
Q

Which commercially important fish species to kelp nurture?

A
  • US rockfish
  • European lobsters
77
Q

Describe sea urchins on kelp

A
  • if reach a high enough population density and following a disturbance, can prevent kelp from regenerating
  • convert a kelp forest into an urchin barren (does not then recover)
78
Q

Describe kelp specialists

A
  • blue-rayed limpet (found at low tide around the UK)
  • sea-urchin (specialises on eating the holdfast)
79
Q

Describe sea urchins

A

very high reproductive rates

80
Q

Describe urchin population control

A
  • top-down controlled
  • by predators, rather than by food
81
Q

Describe Enhydra lutris

A
  • Sea-otters
  • marine mammals
  • feed on shellfish and echinoderms (sea urchins)
82
Q

Describe sea otter hunting for fur

A
  • began in Russia in the 18th Century
  • spread down the W coast of N America during the 19th Century
  • by 1911, reduced to around 2000 animals
  • hunting banned
83
Q

Describe Sea otters and kelp

A
  • around Alaska, significant recovery of kelp forests occurred as sea otters expanded their range
  • pattern repeats along much of the W coast of the US
  • otter = keystone species
  • control urchins
  • allow kelp forests to flourish
84
Q

Describe kelp forests in N California

A
  • collapsed
  • warmer waters, strong El Nino events and a disease of the sunflower sea star
85
Q

El Niño events

A

block coastal upwellings

86
Q

Pycnopodia helianthoides

A

sunflower sea star

87
Q

Describe urchin barrens

A

‘alternative stable state’ phase shift

Hilary Term 1 (61 decks)

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