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Y1 S2 > Marine ecology > Flashcards

Marine ecology Flashcards

1
Q

What is marine ecology?

A

Marine ecology studies the interactions between organisms and their biotic and abiotic environments, and the effects that these interactions have on patterns of distribution and abundance of organisms.

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2
Q

What is evolution?

A

Evolution is a change in genetic compostion of a population over multiple generations

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3
Q

What is micro evolution?

A

Micro evolution is a Phenotypic or life history change within a species

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4
Q

What is macro evolution?

A

Macro evolution is the formation of a new species

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5
Q

What is the difference between abiotic and biotic factors?

A

An abiotic factor is a non-living factor whereas biotic are living

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6
Q

What is the latitudinal diversity gradient?

A

Latitudinal diversity gradient is the increased in species diversity from the poles to the equator

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7
Q

What is zonation?

A

Zonation is latitudinal banding of organisms in a habitat

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8
Q

What are meiofauna?

A

Meiofauna are organisms les than a millimeter in length but bigger than 45 micrometers

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9
Q

What are the different types of primary producers found on rocky shores?

A

*Micro algae
*Seaweeds

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10
Q

What are the different types of micro algae found on rocky shores?

A

*Diatoms
*Cyanobacteria

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11
Q

What are the different types of seaweeds found on rocky shores?

A

*Chlorophyta (greens)
*Rhodophyta (reds)
*Phaeophyta (browns) – fucoids and kelps

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12
Q

What are the major functional groups found on rocky shore habitats

A

*Primary producers
*grazers
*filter feeders
*Predators

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13
Q

What grazers are found on rocky shores?

A

Limpets which feed on diatoms

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14
Q

What filter feeders are found on rocky shores?

A

*Barnicles
*Sponges
*Mussels

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15
Q

What predators are found on rocky shores?

A

*Crabs
*whelks
*birds

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16
Q

How does predation impact rocky shores?

A

*Top down impacts where it changes the distribution and abundance of organisms
*Morphology of prey - predator induced defences (e.g. growing away from prey)

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17
Q

What is zonation of rocky shores?

A

Rocky shores can be divided into 3 zones. High intertidal, mid intertidal and low intertidal, which together are known as the littoral zone

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18
Q

How does exposure impact the organisms on rocky shores?

A

Exposed shores have lots of filter feeders e.g.mussels however sheltered shores are dominated by algae as their is less wave impact for filter feeders food.

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19
Q

What causes patterns of vertical zonation on rocky shores?

A

*Larval settlement
*Physiological tolerance to environmental variables
*Biological interactions
-Interspecific competition
-Predation

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20
Q

Which factors generally limit the upper distributions of rocky shore species?

A

Physical factors eg: humidity, osmotic pressure, high air temperatures

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21
Q

Which factors generally limit the lower distributions of rocky shores?

A

Biological factors eg: competition for space, predation

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22
Q

What is the distribution of larvae types in rocky shores?

A

*70% of benthic invertebrates have planktonic (in the water column) larvae.
*30% of benthic invertebrates have direct developing (eggs on shore which crawl away) larvae

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23
Q

What are the advantages and disadvantages of direct developing larvae?

A

Advantages:
*Predictable food source
*No water column predators
*Suitable habitat ready when hatched
Disadvantages:
* Large reproductive cost for mothers
*Poor dispersal
*Benthic predators e.g. birds

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24
Q

What is Lecithotrophic larvae?

A

Larvae are planktonic using a yolk-sac for nourishment

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25
Q

What are the advantages and disadvantages of lecithotrophic larvae?

A

Advantages:
*Own food supply (egg sack/yolk)
*Less time for predation
*Close to suitable habitat
Disadvantages:
* Fewer larvae produced
*Lower dispersal distances

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26
Q

What are the advantages and disadvantages of planktotrophoic larvae?

A

Advantages:
* Large numbers are produced
*Long time in water column, increasing dispersal distances, creating high geographical species areas
Disadvantages:
* Unpredictable food sources
*Long exposure to predators
*.Last development stage needs to be timed when suitable habitat is found for settlement – high probability of missing the mark!

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27
Q

What is a pelagic larval stage and why have many invertebrates evolved one?

A

It is a period of time during the life cycle spent floating freely in the water column. It means the larvae have a different food source to the parent reducing competition. It also means it can disperse long distance and means there is not a threat of benthic predators (but increased exposure to pelagic predators).

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28
Q

What are the different types of competition?

A

*Exploitative – ability to harvest limiting food resources
*Pre-emptive – competitor recruits to and dominates space
*Interference – competitors physically contest resources

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29
Q

What is intraspecific and inter specific competition?

A

Intraspecific competition is within species whereas inter specific variation is between different species

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30
Q

What are range limits and what affects them?

A

The geographic location where a species is no longer present. Can be affected by habitat availability, genetics, oceanographic and atmospheric factors.

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31
Q

What are the global patterns of sandy/soft sediment habitats?

A

The largest regions of sandy habitat occur within the tropics. Species in the tropics usually have a planktonic larval stage due to big segmentation between beaches and larger dispersal stage. Soft shores are inhabited by mobile epifauna and infauna.

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32
Q

What is porosity?

A

The volume of pore space in between particles.
* Small particles fill up spaces and reduce porosity.
*Large particles = more empty space, increase porosity

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33
Q

What is permeability?

A

The rate of percolation of water through the sediment.
*Low porosity leads to low permeability.
*High porosity leads to high permeability

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34
Q

What are dilatant sands?

A

(Normal sand) When pressure applied, the sand becomes dry and hard packed as water driven out of the interstices. This sand is difficult to burrow into. Few organisms live on them. Lots of wave action, so a harsh environment. Common on exposed beaches.

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35
Q

What are thixotropic sands?

A

(Quick sands) Sands with high clay content become wetter and more easily penetrated when agitated. This sand is easier to burrow into.

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36
Q

What are muds?

A

Do not drain and are saturated with water. These are soft and easy to burrow into.

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37
Q

What is the connection between oxygen and sediment chemistry?

A
  • Aerobic bacteria decompose organic material at the surface where oxygen is abundant
    *Oxygen consumption at the surface deprives deeper layers of oxygen, so sediments below the surface are anaerobic
  • The depth of the oxygenated layer varies according to the grain size of the shore – which determines its permeability
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38
Q

What is the redox discontinuity layer?

A

As oxygen concentrations diminish with depth, anaerobic bacteria start to dominate. The transition layer between oxygen-rich and oxygen-poor layers is the redox discontinuity layer. This varies due to porosity and exposure.

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39
Q

What are siphons?

A

Some animals extend a long siphon into the oxygenated waters so they can respire and feed while sheltered from predation deeper in the sediment

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40
Q

What is the distribution of plants in sandy/muddy environments?

A
  • Generally no macroalgae, but sometimes see blooms of sea lettuce on mudflats
    *Brown seaweeds present if attached to pebbles
    *Benthic diatoms form biofilms and live at surface for photosynthesis
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41
Q

What is macrofauna?

A

Organisms that are bigger than 1mm

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42
Q

What is the distribution of macrofauna in sandy/muddy environments?

A

*deposit and filter feeders are common but the distribution depends on exposure and wave action. E.g.more
filter feeders when wave flow is high.
* Predators e.g. shore crabs, birds

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43
Q

What is the distribution of meiofauna in sandy/muddy environments?

A

*Lots of nematodes, which are more common in sandy than muddy shores (80% of animals are nematodes)

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44
Q

How does sediment stability impact distribution of macrofauna?

A

Species richness, abundance and total biomass increase with increasing sediment stability (decreased wave exposure).Highest in muddy/sheltered habitats

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45
Q

How does tidal height impact distribution of macrofauna?

A

Tidal height does not cause much zonation in muddy and sandy shores as the sediment allows for burrowing away from physical stressors.

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46
Q

How does sediment depth impact the distribution of macrofauna?

A
  • Some sediment depth is due to siphon length, to allow for oxygen
  • Sediment depth can also be due to competition with different species
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47
Q

What are biostabilisers?

A

*Increase cohesiveness (stickiness)
*Make sediment surface smoother
*Form protective layer over sediment surface

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48
Q

What are bioturbators?

A

*Make sediment surface rougher
*Regrade the sediment particle structure
*Reduce sediment strength
*Oxygenate sediment

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49
Q

What is an estuary?

A

An extended interface between a marine and flowing freshwater (lotic) system

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50
Q

What is the distribution of organisms in estuaries?

A

There is a big mixture of organisms due to the mixing of fresh and salty water
*Invertebrates dominate both epifauna and infauna. E.g. crabs and shrimps
*Fish use estuaries as nursery grounds or move in with tides / migration. E.g. salmon
*Birds migrate E.g. geese
*Plankton are mainly diatoms and dinoflagellates

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51
Q

What are the salinity profiles of estuaries?

A

A balance between volume of river flow and strength of tide – water density. There is both vertical and horizontal variation.

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52
Q

What is a osmoconformer?

A

The osmotic pressure within animal’s cells are equal to the surrounding water

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53
Q

What is an osmoregulator?

A

Active regulation of osmotic pressure within cells

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54
Q

What are euryhaline organisms?

A

Tolerates large salinity range (many estuarine species)

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55
Q

What are stenohaline organisms?

A

Tolerates only a narrow salinity range

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56
Q

What are behavioural adaptations of estuarine species?

A

*Some species move in and out of the estuary with the tide
*Some bury their head in the sand to reduce fluctuations in interstitial fluids in sediments

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57
Q

What is the deep sea

A

The deep sea is beyond 200 metres water depth ( most of the ocean is deep sea environments)

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58
Q

What is the dysphotic zone?

A

The dysphotic zone, also known as the twighlight zone occurs at mid-water depths between 200-1000m. There is still some photosynthesis but there is not enough sunlight for net primary production. 90% of animals are bioluminescent

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59
Q

What is bioluminescence?

A

Bioluminescence is created by the oxidation of a luciferin substrate via a luciferase enzyme. Most bioluminescence in the deep sea is blue wavelength as it attenuates less quickly and matches down-welling light.

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60
Q

What are the uses of bioluminescence?

A

*Signalling to conspecifics (members of the same species)
*Catching prey
*Evading predators
*Counter-illumination

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61
Q

What is counter-illumination?

A

Counter-illumination only occours in the dysphotic zone. As there is still some downwelling irradiance (sunlight), animals cast a “shadow” beneath them. Many dysphotic zone animals have sensitive upward-looking eyes to detect these shadows so animals can use their bioluminescence to mask their silhouettes.

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62
Q

How is bioluminescence used to catch prey?

A

Either by using bioluminescent lures (to attract prey) or by illuminating prey during hunting
*Dragon fish use red light that is invisible to most deep-sea animals (which stops the prey from detecting being targeted and taking defensive action)

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63
Q

How is bioluminescence used to evade predators?

A

*To confuse predators (e.g. expelling bioluminescent fluid).
*To discourage predation according to the “burglar alarm” hypothesis - making a display attracts potential predators of the predator that threatens them

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64
Q

What is the aphotic zone?

A

The aphotic zone, also known as the midnight zone, is deeper than 1000m where there is no more down-welling sunlight. Prey can be increasingly scarce therefore adaptations for predation, & predator evasion, are increasingly apparent.

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65
Q

What is ultra-black?

A

It reduces reflectance of bioluminescence to less than 0.5%

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66
Q

What are continental slopes?

A

Continental slopes are inclines which begin at 200m of off continents towards the ocean basin.

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67
Q

What are deep-water corals?

A

Deep water corals are scleractinians (stony corals) but do not have photosynthetic zooxanthellae. This means they have a slow growth rate which makes them particularly vulnerable to damage by bottom-trawling of deep-water fisheries

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68
Q

What are abyssal plains?

A

Flat regions of the ocean floor with gradients less than 1:10000. There is high species richness of macrofauna living in sediment (e.g. molluscs) and can have high species richness of meiofauna. A lot of the organisms burrow into mud

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69
Q

What are seamounts?

A

Active or extinct undersea volcanoes rising more than 1000 m above the surrounding seafloor. Steep slopes provide bare rock surfaces for attachment of suspension feeders
Enhanced flow around seamounts provides increased food

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70
Q

What are mid-ocean ridges?

A

Formed from moving tectonic plates. They are similar to seamount habitat

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71
Q

What are ocean trenches?

A

Ocean trenches normally start at 6000m depth. Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They funnel organic input such as marine snow, reducing the rate of decline in food availability with depth

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72
Q

What is the relationship between pressure and depth in the ocean?

A

Pressure increases by ~1 atmosphere per 10 m depth - at 5000 m, ambient pressure is >50,600 kPa

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73
Q

What are chaperone molecules?

A

As depth increases internal and external pressures are equalised in most organism tissues but pressure can trap water on surfaces of unfolded proteins inside cells, preventing them from folding into the necessary shape for correct enzyme function. Chaperone molecules remove water molecules from unfolded proteins & promote correct folding

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74
Q

What is TMAO?

A

TMAO is a chaperone molecule used by fish and decapod crustaceans. As depth increases TMAO levels also increase

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75
Q

What is the deepest known fish?

A

A species of snail foist found at 8178m in Mariana Trench

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76
Q

What are some adaptations of ocean trench species?

A

Exoskeletons of trench-living amphipods are coated by an aluminium hydroxide gel that protects their calcite mineral content from dissolving under pressure

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77
Q

What are the different feeding strategies in the deep sea?

A

*predation
*Suspension-feeding
*Deposit-feeding
*scavenging
*exploiting larger organic falls

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78
Q

What are the characteristics of predation in the deep-sea?

A

*Common in the aphotic & dysphotic
* Many deep-sea predators have adaptations to tackle large prey relative to their own body size - flexible jaws, expandable stomachs, additional neck joints

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79
Q

What are the characteristics of suspension feeding in the deep-sea

A

Suspension feeding is the capture and ingestion of food particles that are suspended in water. There are two challenges:
* Need to escape boundary layer where seabed friction reduces flow. To overcome this many species have evolved stalks or colinise upstanding features
*Need to anchor if stalked

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80
Q

What are the characteristics of deposit feeding in the deep-sea?

A

Deposit-feeders extract organic matter from sediment. There are 3 types:
*Batch reactor - with one entrance/exit
*Continous-flow stirred tank reactor - with separate entrance and exit
*Plug-flow reactor - with separate entrance and exit but a continuous input and output

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81
Q

What are the characteristics of scavenging in the deep-sea?

A

Many benthic deep-sea scavenger species have olfactory and other sensory adaptations to detect food-falls

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82
Q

What are the characteristics of exploiting larger organic falls in the deep-sea?

A

Some organic input to the deep-sea benthos is much larger than particulates in size (e.g. larger animal carcasses & “wood-falls”)
Some taxa are specialists in exploiting these resources, often through partnerships with symbiotic bacteria

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83
Q

What are different reproductive adaptation in the deep-sea?

A

*pairing behaviour
*accessory dwarf males
*opportunistic mating behaviour
*aggregation of broadcast spawners

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84
Q

What is the size difference between deep-sea and shallow water organisms?

A

Most deep-sea species are smaller than their shallow water relatives. Normally due to less food availability than upper ocean

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85
Q

What is gigantism?

A

Deep-sea body sizes being much larger than their shallow-water relatives

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86
Q

What is chemosynthetic primary production?

A

Fixation of inorganic carbon using chemical energy. Reduced chemical compounds provide a source of electrons

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87
Q

What is the process of chemosynthetic primary production?

A

*2-stage process very similar to photosynthesis:
(1) production of “reducing power”
(2) fixation of inorganic carbon (e.g. CBB cycle)
*Process requires a terminal electron acceptor (e.g. oxygen, in AEROBIC chemosynthesis)

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88
Q

What organisms carry out chemosynthetic primary production?

A

Prokaryotic microbes E.g. Archaea and bacteria

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89
Q

What are the possible electron donors in chemosynthetic primary production?

A

H2S, CH4, H2, iron Fe(II), manganese Mn(II)

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90
Q

What are the possible electron acceptors in chemosynthetic primary production?

A

O2, NO3 - , SO4 2- , iron Fe(III), S

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91
Q

What determines which chemosynthetic pathway is present in a micro-environment?

A
  • availability of electron donors
    *availability of electron acceptors
    *energy yield of the reaction
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92
Q

Where do faunal assemblages occour in chemosynthetic environments?

A

They occur where reduced chemicals are available at the ocean floor:
*hydrothermal vents
*cold seeps
*whale falls
*wood falls

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93
Q

What is hydrothermal circulation?

A

Entire global ocean volume passes through hydrothermal circulation every ~104years
Removes Mg and SO4 from seawater (which helps to maintain the salinity of the oceans)

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94
Q

What are black smoke vents?

A

Hydrothermal vents at high temperatures (over 350’C) which erupt at high flow rates. Iron and other metals in the fluid precipitate as they mix with seawater, forming ‘black smoke”

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95
Q

What are white smoke vents?

A

Hydrothermal vents at lower temperatures (below 200’C) which seep through small cracks. Lower metal concentrations and particles of anhydrite, barite, or talc forming “white smoke”

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96
Q

What are the characteristics of temperature gradients at vent sites?

A

Highest temperatures only occur in primary vent fluid at the throat of the vent chimney. There are very sharp gradients. 360 ºC to 2 ºC over 10s of cms

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97
Q

How does chemosynthesis occur at vents?

A

Sulfide oxidation is the mains form of chemosynthesis in terms of carbon fixation. Hydrogen sulfide (H₂S) is readily available in vent fluids and oxygen is readily available from background deep-sea water

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98
Q

How do animals exploit chemosynthesis?

A

*endosymbiotic relationships
*microbial epibionts (an organism that lives on the surface of another)
*by grazing or suspension feeding of free-living microbes
*by predation / scavenging on primary consumer animals

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99
Q

What is special about the Riftia species?

A

These tubeworms don’t have mouths, anus or guts so don’t have a digestive system.
Instead they have a trophosome which contains lots of chemosynthetic bacteria (they’re endosymbionts). This bacteria creates energy for the tube worm by chemosynthesis

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100
Q

What do the endosymbionts of Riftia need for chemosynthesis?

A

For chemosynthesis they need inorganic carbon (to turn into sugars), oxygen (as the terminal electron acceptor) and hydrogen sulfide (as the energy source). The worm acquires these from its environment and transfers it to the bacteria inside.

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101
Q

Characteristics of inorganic carbon for endosymbionts of Riftia

A

It can be obtained from either:
*Heterotrophic CO2 from Riftia tissues (by the worms respiration)
*Vent fluids or deep-sea water

DIC transported in blood as HCO3 - and CO2

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102
Q

Characteristics of sulfide for endosymbionts of Riftia

A

PROBLEM: hydrogen sulfide is highly toxic to animal tissue
*it poisons cytochrome c oxidase electron transport enzyme
*usually replaces oxygen at binding site on haemoglobin

Riftia take up HS- (less toxic form for cytochrome c oxidase)

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103
Q

Characteristics of oxygen for endosymbionts of Riftia

A

Riftia haemoglobin has high affinity for O2.
Can have environmental temperature gradient along worm body (warmer at trophosome than worm plume) may aid unloading of O2 at trophosome

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104
Q

What is special about the mussels Bathymodiolus spp. species?

A

They can host dual symbioses inside their gill cells. Both sulfide-oxidising and methanotrophic bacteria.

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105
Q

What are the characteristics of animals at vents with epibionts

A

Some animals at vents have epibiotic bacteria (lives on their surface). Roles may include nutrition and detoxification. The animals may have an increased surface area to allow for their epibionts.

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106
Q

What are the characteristics of grazers at vents?

A

They graze on bacteria present either as biofilms or mats of filamentous bacteria. Grazers include limpets and polychaetes

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107
Q

What are the characteristics of filter feeders at vents?

A

They filter-feed on organic matter at vents - e.g. Eolepadid stalked barnacles

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108
Q

What is zonation at vent sites?

A

Steep physical-chemical gradients at vents on similar scale to rocky intertidal environment, gradients include temperature, sulfide & O2 concentration.

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109
Q

What is the different species zonation at vent sites?

A

Closest zone to active vents is often dominated by species that can feed on e-proteobacteria. The next zone is often dominated by species that show trophic relationships with g-proteobacteria. Filter-feeding species then extend further away from vents and then a “halo” of non-vent animals possibly 100s of metres from vent

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110
Q

Why is there a zonation in e- and g-proteobacteria (and therefore their holobionts) around vents?

A

e bacteria can respire using S as an electron acceptor therefore it can thrive closer to vents where there is a greater diversity of electron donors and less O2 whereas g bacteria require O2 for their two S-oxidising metabolic pathways, so are restricted to zones with greater mixing with seawater

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111
Q

Why do hydrothermal vents have an insular nature?

A

Hydrothermal vents occur in “fields” (clusters of vent chimneys) depending on the underlying geology: the availability of heat source and pathways for circulation. On a fast-spreading mid-ocean ridge (e.g. East Pacific Rise), vent fields may be 10s of km apart. On a slow-spreading mid-ocean ridge (e.g. Mid-Atlantic Ridge), vent fields may be 100s of km apart

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112
Q

Why do hydrothermal vents have an ephemeral nature?

A

Vents don’t last forever. Volcanic eruptions or tectonic activity can disrupt the “plumbing” of the vents. How long a vent field lasts depends on how frequently these types of disturbance occur. Vent fields on a fast-spreading mid-ocean ridge (e.g. East Pacific Rise) may only last for 10s of years. Vent fields on a slow-spreading mid-ocean ridge (e.g. Mid-Atlantic Ridge) may last for 1000s of years

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113
Q

What is a cold seep?

A

Environments where non-volcanic geological processes generate reduced chemicals at the seafloor to support chemosynthesis

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114
Q

What are the types of cold seep environments?

A

*salt diapir system
*mud volcanoes
*asphalt seeps
*methane hydrate beds

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115
Q

Where are cold seeps found?

A

Typically found on continental margins but can also occur in ocean trenches. Generally found in soft-sediment seafloor settings

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116
Q

How do cold seeps form?

A

Geological process forces organic compounds from deep reservoir up through seafloor sediments. Hydrocarbon sediments are buried which degrade to produce methane. Anaerobic
subsurface microbes oxidise methane using SO4- to produce HS- + HCO3- +H2O. This sulfide provides an energy source for chemosynthesis.

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117
Q

What is salt diapirism cold seeps?

A

A salt flat is buried as sea levels change. There are now new sediment laying on top however the rocks salt below is more buoyant so is trying to crack its way up to the surface. This vertical movement of salt up through the seafloor sediment is salt diapirism

118
Q

What is the ecology around a salt diapirism e.g.brine pool gulf of Mexico?

A

The brine pool is anoxic and hypersaline surrounded by bed of mussels. There are also grazers like gastropods and polychaetes and scavengers like shrimp and lobsters. Species zonation occurs following gradients in sulfide flux and oxygen conditions

119
Q

What is the difference between worms at hydrothermal vents and at cold seeps?

A

Seep tubeworms acquire sulfide via their roots, not their plumes.

120
Q

Why do cold seeps have an ephemeral nature?

A

They don’t last forever because reactions such as methane oxidation happening under the sediments produce bicarbonate which causes biogenic carbonate rock to form in the sediment under the seep site. This carbonate rock eventually blocks seeping of methane at the site

121
Q

Why are some animals from cold seeps slow-growing and long-lived in comparison to hot vent fauna?

A

The delivery of reduced chemicals is slower, thus primary production is lower, and the environments are more stable

122
Q

What is chemosynthesis at whale falls?

A

Degradation of whale carcasses on the ocean floor can result in a partially chemosynthetic environment, there are still heterotrophs present. Non-chemosynthetic scavengers remove flesh from skeleton & bone. Whale bones are very rich in lipids & anaerobic bacteria then break down these lipids, reducing seawater sulfate to sulfide in the process, resulting in a sulfide flux which can support chemosynthetic primary production by other microbes

123
Q

Why are whale falls ephemeral?

A

Whale skeleton lipids are eventually depleted after decades

124
Q

Why are whale falls insular?

A

The whale carcasses from little islands with distances typically around 10s of km

125
Q

What is chemosynthesis at wood falls?

A

Large amounts of wood are swept out to sea from rivers creating a partially chemosynthetic environment. some species exploit wood falls heterotrophically but microbes digesting cellulose in wood can also release sulfide which can support other chemosythetic microbes.

126
Q

How do vent habitats increase speciation?

A

They interrupt gene flow between populations by:
*geographical isolation by movements of plates and ridges
*changes in ocean currents
Dispersal of fauna is usually achieved by larval stages

127
Q

What are the causes of ocean basin circulation?

A

*Major global wind patterns due uneven heating of the earth by the sun due to its angle
*Latitudinal variation in the coriolis force (deflection of winds to the right in the Northern Hemisphere and deflection to the left in the Southern Hemisphere.)

128
Q

What is Ekman transport?

A

Surface currents are at a 45 degree angle to the wind. Right in Northern hemisphere and Left in southern. As we go deeper in depth the angle increases, known as the Ekman spiral. This means currents move at 90 degrees to the wind, known as Ekman transport.

129
Q

What are the 5 major subtropical gyres?

A

*north pacific
*north atlantic
*south pacific
*south atlantic
*indian ocean

130
Q

What are gyres?

A

Huge circular moving current systems which dominate the surfaces of the oceans. Because of coriolis and Ekman spiral they turn clockwise in northern hemisphere and anti-clockwise in southern hemisphere.

131
Q

What are the trends in sea surface temperatures?

A

Sea surface temperatures are high in the mid latitude due to high levels of irradiance in comparison to low latitudes and polar regions

132
Q

What are the trends in sea surface salinity?

A

Driven by evaporation and precipitation. High evaporation = high salinity. Inter tropical convergence zone creates a lot of precipitation so not as simple as temperature map with poles to equator difference

133
Q

What is an oligotrophic environment?

A

Low concentrations of essential nutrients for algal growth. They generally support low levels of primary production.

134
Q

What is a eutrophic environment?

A

High concentrations of essential nutrients for algal growth. They generally support high levels of primary production.

135
Q

What are the trends in sea surface nitrate?

A

Nitrate levels are generally low but there are higher levels in the southern ocean

136
Q

What is the western boundary current in the gulf stream?

A

A warm current flowing along the the eastern coast of North American content north. It helps form the Sargasso Sea gyre

137
Q

What factors affect primary production?

A

*nutrients
*sea surface temperature
*physical factors that can cause upwelling

138
Q

What are meso-scale eddies?

A

Meso-scale eddies are approximately 100km and 1 month. They pump nutrient-rich waters from depth and can be described as the weather of the ocean

139
Q

How do eddies increase primary production?

A

They pump nutrient-rich waters from depth stimulating new phytoplankton which zooplankton can graze on

140
Q

How do new nutrients enter the euphotic zone?

A

New nutrients enter the euphotic zone from an outside system e.g. the atmosphere, deep waters and rivers

141
Q

What is the f-ratio?

A

The ratio of nitrate (NO3) uptake by phytoplankton to total inorganic (NO3, NO2, NH4) and organic (e.g. urea) uptake by phytoplankton.

142
Q

What is the difference between the old ad new views of subtropical gyres?

A

The old view said the overall biomass and production was very low and they where inefficient ecosystems with nutrient-limited growth. The new view agrees that production is low but there are seasonal varitions which allows for blooms of organisms.

143
Q

Why are subtropical gyres dynamic systems?

A

They have episodic mixing events which are important for annual production. 65% of annual production occur in 2 weeks

144
Q

What is the most common size of plankton in autotrophs?

A

Picoplankton

145
Q

Why can larger plankton be important?

A

*Fresh supply of new nutrients
*Larger species - diatom blooms

146
Q

Where do smaller plankton dominate?

A

Regions where nutrient levels are low, regeneration

147
Q

Where do larger plankton dominate?

A

Regions with high levels of nutrients - no need of regenerated nutrients.

148
Q

Why are atmospheric dust inputs such as the saharan dust important?

A

The enzyme responsible for N-fixation (nitrogenase) requires high amounts of iron.

149
Q

When does nitrogen fixation occur?

A

When there are no other inputs of nitrogen. Trichodesmium is the dominant N2-fixing organism in the ocean

150
Q

What is the role of the vertical migration of phytoplankton?

A

They vertically move nitrate (NO3) up from depths when levels are depleted

151
Q

What is the microbial loop?

A

It dominates when there is nutrient-limitation. Dissolved organic materials such as carbon is returned to higher trophic levels via its incorporation into bacterial biomass, and then coupled with the classic food chain formed by phytoplankton and zooplankton.

152
Q

What is bottom up control in food webs?

A

Lower trophic levels are the limiting factor, it relys heavily on how much phytoplankton are growing

153
Q

What is top down control in food webs?

A

Predators and higher trophic level control the food web by removing lower levels.

154
Q

What is the continental shelf?

A

The continental shelf is part of the continental land mass however is submerged under water. It ends at 200m depth where there is then a steep decline gradient

155
Q

How much of the global ocean contains a continental shelf?

A

8%

156
Q

What are phytoplankton?

A

They drift within ocean currents and photosynthesise to produce their own food

157
Q

What is the difference between eukaryotic and prokaryotic cells?

A

*Eukaryotic cells contain a nucleus and organelles bound by plasma membranes
*Prokaryotic cells don’t have a membrane-bound nucleus or organelles

158
Q

What are the different types of phytoplankton?

A

*Cyanobacteria
*Dinoflagellates
*Diatoms
*Coccolithophores

159
Q

What are the characteristics of Cyanobacteria?

A

They are prokaryotes and have the highest diversity in tropical zones. They have symbiotic asscociations for example with sponges. They are a single long filament

160
Q

What are the characteristics of dinoflagellates?

A

They are the 2nd most abundant phytoplankton group. They can be autotrophic, heterotrophic or mixotrophic. They are motile as have 2 flagella. Their blooms form red tides and some species are toxic

161
Q

What are the characteristics of diatoms?

A

They are found in all aquatic environments and are the most abundant phytoplankton group.
They have a silica frustle skeleton and are non-motile.

162
Q

What are the characteristics of coccolithophores?

A

They reflect sunlight and heat back out of the water. They are formed from CaCO3

163
Q

What do autotrophs need to photosynthesise?

A

*Light (energy source)
*CO2 (carbon source)
*O2 (for respiration)
*Nutrients (to make cell structures)

164
Q

What elements do Proteins, lipids, nucleic acids and nucleotides contain?

A

N, P, S

165
Q

What element is in diatom skeletons?

A

Si (silicon)

166
Q

What is the redfield ratio?

A

C:N:P = 106:16:1

167
Q

What are the different types of nitrogen in the oceans?

A

NO3, NO2, NH3, N2

168
Q

What are the different types of phosphorus in the oceans?

A

HPO4^2-, PO4^3-, H2PO4^-

169
Q

What are the different types of sulphur in the oceans?

A

S04^2-, H2S

170
Q

What are the different types of carbon in the oceans?

A

CO2, HCO^3-, CO2^3-, H2CO3

171
Q

What are the 3 light penetration levels in the ocean?

A

*Euphotic zone - the sunlight zone where photosynthesis can occour
*Dysphotic zone - the twighlight zone where sunlight decreases rapidly with depth and photosynthesis is not possible
*Aphotic zone - where sunlight cannot penetrate

172
Q

What is the light extinction coefficient?

A

It measures the depth light can penetrate and depends on wavelength, dissolved material and particles.

173
Q

What can sunlight penetrate further in ocean or costal waters?

A

Sunlight penetrates ocean waters further than coastal waters as it contains less output from the shore

174
Q

What is PAR?

A

Photosynthetically Active Radiation. Phytoplankton can only use certain colours of radiation, between 400-750 nm

175
Q

What is the P/E curve?

A

It compares the rate of photosynthesis to the level of light. X axis = irradiance, y axis = photosynthetic rate

176
Q

What is irradiance?

A

Radiant flux per unit area received by a surface

177
Q

What is photoinhibition?

A

Photoinhibition is when photosynthesis starts to decrease - perhaps due to physical damage from too much light or the cell shutting down to stop any possible damage

178
Q

What is the critical depth model?

A

It compares respiration and photosynthesis rate. When respiration = photosynthesis there is just enough sunlight for organisms to photosynthesise and survive.

179
Q

What are the seasonal trends in primary production?

A

In wintertime the thermocline is none existent so has little to no impact. This means there is a lot of nutrients as there is a lack of sunlight so they are not being uses up. Then in spring there is a good balance of nutrients and sunlight for optimum photosynthesis In summer zooplankton levels rise as there is big blooms of phytoplankton however the zooplankton then eat the phytoplankton so levels drop.

180
Q

What are the characteristics of zooplankton?

A

*They have little ability to swim against major water currents.
* They play key roles in pelagic food webs and biogeochemical cycling.
*Most are heterotrophs but some are mixotrophs
*Patchy distribution is a very common feature of zooplankton, occurring at a variety of spatio-temporal scales. It is partly due to the fact they are motionless so move due to physical processes such as gyres, eddies and tidal mixing

181
Q

What are langmuir vortices?

A

They are a powerful mechanism of vertical mixing in natural bodies of water, driven by wind and waves. They are a series of shallow, slow, counter-rotating vortices at the ocean’s surface .

182
Q

What is diel vertical migration of zooplankton?

A

Zooplankton moving up and down the water column each day due to light variations. Preferred depth ranges vary with life stage, weather, season and latitude.

183
Q

What is seasonal vertical migration of zooplankton?

A

They lay their eggs at depth Dec-April. The population matures at surface when primary productivity is high. By June, storage lipids are accumulated and they migrate to deeper waters in autumn. The causes are temperature and food availability

184
Q

What is the relationship between food web length and energy?

A

Short food chains deplete less energy prior to consumption, compared to long food chains. At each step energy and heat is lost through processes such as metabolism. Nutrients are also lost e.g. feces

185
Q

What are the efficiency rates for different trophic levels?

A

For trophic level 1, the average transfer efficiency is 2% (98% loss); all other trophic levels average 10% efficiency (90% loss)

186
Q

What is the growth yield equations (Ygr)?

A

Growth/Growth + Respiration
or
Growth/Food intake

187
Q

What does growth yield depend on?

A

*Type of organism
*Level of complexity
*Swimming ability
*Life-history stage

188
Q

What is the trophic yield equation (Yt)?

A

Growth at trophic level t+1/Growth at trophic level t

189
Q

What is ecological efficiency?

A

Energy transferred between trophic levels

190
Q

What is the difference between food webs and food chains?

A

Food chains are linear. Food webs take into account complex systems with interconnected food chains

191
Q

What is a rocky reef?

A

Non-living hard substrates that are usually found along continental shelves in temperate and subtropical areas

192
Q

What is a kelp forest?

A

A rocky reef with canopy forming kelps that reach sea surface. They are highly productive and add structural vertical complexity allowing for the survival of more species. Kelp forests can refer to any type of brown seaweed that can form a canopy

193
Q

Why are kelp forests important?

A

*Significant primary production and carbon sequestration
*Regulate the recruitment of coastal species by providing food and shelter
*Important habitat for a number of juvenile fish - they can hide within the forest
*Provide buffering and protection against the effects of waves and storms

194
Q

What is the photosynthesis equation?

A

6CO2+6H2O→C6H12O6+6O2.

195
Q

What is true kelp?

A

It makes up the order Laminariales. They are are large brown subtidal seaweeds with very strong holdfasts to stay attached to rocks.

196
Q

What are the features of seaweed / general kelp?

A

*Flat blades - with high SA:V ratio for nutrient absorption
*Air filled pneumatocysts - allow blades to float close to the surface for photosynthesis
*Stipe - which link blades to holdfasts and are used for shock absorption from wave impact
*Holdfasts - which ancghor kelp seaweeds to the bottom

197
Q

What are the different sections of rocky reef kelp ecosystems?

A

*Canopy
*Understory
*Algal turf

198
Q

What is the canopy?

A

Fronds lying on surface or midwater. It has the most light and wave action

199
Q

What is the understory?

A

Fronds erect or close to bottom. They have the highest diversity of marine life in the kelp forest and are the area of stipes.

200
Q

What is the algal turf?

A

Short clumps, filaments and encrusting algae. Area of holdfasts of larger kelp, invertebrates, and red algae

201
Q

What is Steller’s sea cow (Hydrodamalis gigas)?

A

They where found in the northern pacific and grazed almost exclusively on kelp in the canopy. They had no teeth just broad bony pads to chew kepl. They where hunted to extinction approximately 250 years ago. This was influenced by only a few offspring produced every year and long generation times.

202
Q

What organisms are associated with algal turf?

A

Small invertebrates, adult rockfishes, kelp bass, sheaphead and abalone

203
Q

What is the distribution of kelp forests?

A

They are found in areas with high nutrients, often this is due to high upwelling. The tropics are too hot and nutrient poor

204
Q

What controls the distribution of kelp beds?

A

*Substrates
*Light
*Nutrients

205
Q

What causes kelp deforestation?

A

*Environmental reasons such as El Nino , where there is less upwelling so warmers water temperatures and less nutrients
*Biological reasons such as hunting of predators of kelp predators
*Storms

206
Q

What is the relationship between kelp beds and upwelling?

A

Upwelling is important for kelp beds because it brings cold nutrient rich waters to the surface. Upwellings are seasonal, but they also vary among years (e.g. El-Nino events). Kelp forest abundance follows the pattern of El Niño / La Niña years

207
Q

What is the relationship between kelp and urchins?

A

Sea urchins are herbivores and potentially destructive to kelp. Urchins normally passively feed on drift kelp (free-floating kelp detritus). When drift kelp is limited, and urchins start to experience food limitation, their feeding behaviour changes to live kelp. When urchins get out of control, they initiate a “phase shift” in kelp bed ecosystems to urchin barrens.

208
Q

What are phase shifts?

A

When an ecosystem changes from one stable state to another due to perturbations. E.g. kelp forest to urchin barren

209
Q

What is a trophic cascade?

A

A chain-reaction within food webs that results from changing population densities at higher trophic levels, shifting the dominance and impact of consumers in lower levels

210
Q

What is the Arctic?

A

The frozen ocean. It is an ice-covered ocean surrounding the North pole land. It is a 14.5 million km2 ocean basin

211
Q

What is the geological history of the arctic?

A

It used to be divided into two basins. The Eurasian Basin formed during the Cenozoic era and the Amerasian Basin formed earlier during the Mesozoic era. Opening of Fram Strait 17.5 Mya - changed the arctic from an oxygen poor lake stage to an estuarine sea with more oxygen.

212
Q

What is Antarctica?

A

The frozen continent which is 14 million km2 and mountainous

213
Q

What is the geographical history of antarctica?

A

The breakup of the supercontinent Gondwana 180 mya slowly lead to the oceanographic isolation of antarctica 40 mya

214
Q

What are the similarities and differences of arctic and antarctic physical features?

A

*Both high latitude and polar
*Both cold water systems with very low sea surface temperatures
*Arctic continental shelf = 200m deep, Antarctica continetal shelf = 500 m deep (due to the continent pushing it down)
*Arctic = North pole, Antarctic = South pole

215
Q

What are the similarities and differences of arctic and antarctic temperature?

A

*Both areas have very cold air and water temperatures due to low solar angles in high latitude areas and albedo of ice
*Both continents are very dry as colder air can’t hold as much moisture as warm air
*Arctic wintertime = -40C summer 0C, Antarctic wintertime = -60C summer = -28.32C

216
Q

Why is the antarctic colder than the arctic?

A

The main reason the antarctic is slightly colder than the arctic is because it is a huge land mass so receives very little heat from the ocean whereas as the antarctic is heated by the ocean.

217
Q

What are the two types of ice?

A

*Glacier ice (glaciers & icebergs)
*Sea ice (pack ice & multiyear ice)

218
Q

What are the similarities and differences of arctic and antarctic ice?

A

*Both the Arctic and Antarctic have both kinds of ice
*There is a lot of annual ice in the Antarctic due to advance and retreat of the sea ice
*There is a lot of multiyear ice in the Arctic as the centre of the arctic melts completely every year

219
Q

What is glacier ice?

A

Glacier ice is compacted snow. It is made entirely of freshwater. Where glaciers meet the sea, they can carve and form icebergs which can float out to sea

220
Q

What is sea ice?

A

Sea ice is formed from freezing seawater. The density of seawater increases as it cools, it freezes at about - 2C. Annual ice is sea ice which forms every year and melts again.

221
Q

What is Arctic basin circulation?

A
  1. Bering Strait - cold and less salty water enters the arctic ocean
  2. Chukchi Sea - very cold winds coming from land masses surrounding the arctic blow onto the sea water and start the freezing process. As seawater freezes it rejects salt so surface seawater is a lot fresher. Dense salty seawater sinks into the western arctic ocean.
  3. Beaufort Gyre - Once the water is fully in the Arctic ocean it is circulated around the gyre
  4. Transpolar Current - wind shifts (the transpolar current) in direction and the Beaufort gyre weakens
  5. Various exit gateways - weakened gyre allows very big volumes of freshwater to leak outside the Arctic.
  6. North Atlantic current - warm salty water enters the Arctic and cools the further it goes in flowing anti-clockwise
222
Q

What is southern ocean circulation?

A

Antarctic Circumpolar Current (ACC). It flows West -East (clockwise) and is the largest wind-driven current. There is convergence where cold antarctic waters meet warmer sub-antarctic waters, because they are more cold at the convergence the antarctic waters sink under the sub-antarctic waters

223
Q

What plants are found in the arctic and antarctic?

A

Arctic - tundra
Antarctic - two flowering plant species

224
Q

What animals are found in the arctic and antarctic?

A

Arctic - Many terrestrial mammals (e.g. reindeer)
Antarctic - No terrestrial mammals
Both have many marine mammals e.g. seals and whales

225
Q

What is important in the antarctic southern ocean food web?

A

Krill

226
Q

What is the difference between human presence in arctic and antarctic?

A

*The arctic has a government and there are more than 4 million people lving there.
*The Antarctic has no government and nor permanent residents, just scientists

227
Q

What is classed as the Southern ocean?

A

All water south of the polar front so is oceanographically isolated. It has low stable temperatures and a deep continental shelf.

228
Q

What where the origins of the unique seafloor community in the Southern ocean?

A

Cooling 40Mya and the opening of the Drake passage established the polar front and antarctic circumpolar current (ACC) which creates the isolation and a glaciated environment. The isolation allows for evolution of diverse fauna in the Antarctic

229
Q

What is unique about the Southern ocean seafloor community?

A

*Stenotherms (-1.85 to +2 deg C)
*Slow physiological rates

230
Q

How in the Antarctic changing?

A

Warming of air and sea surface temperatures are now starting to impact all of the Antarctic and not just the North. Glaciers are retreating at a higher rate to the rate of glaciers advancing, there ae increases in precipitation and sea ice seasons are shortening

231
Q

Why do we study Antarctic benthos? (seafloor organisms)

A

Antarctic benthos are extremely vulnerable to climate warming sue to their strict physiological limits (e.g. stenothermy) and slow physiological relates. Antarctic benthos are a useful barometer for climate change and other species in different areas

232
Q

Will ice melt and loss in Antarctica be significant?

A

Benthic organisms may be impacted by an increase in icebergs which scour the seafloor

233
Q

What is evolutionary ecology?

A

How/why do interactions between organisms and their biotic and abiotic environments affect the genetic composition of marine populations?

234
Q

What is speciation?

A

The formation of one or more species from an ancestral species. Speciation occurs when populations of the ancestral species become reproductively isolated from each other.

235
Q

What are the steps of speciation?

A

*Population with a common gene pool - the ancestral species
*Populations become reproductively separated
*Genetic differences (e.g. mutations) build up between the populations, creating morphological variation
*Natural selection
*After a long time, if the two populations come into contact, they can no longer interbreed

236
Q

What is natural selection?

A

The differential survival and reproduction of individuals due to differences in phenotype.

237
Q

What are the different types of speciation?

A

*Allopatric
*Peripatric
*Paripatric
*Sympatric

238
Q

What is allopatric speciation?

A

When two or more populations become completely geographically (and hence, reproductively) isolated. Over time, genetic and morphological differences accumulate, causing the formation of new species.

239
Q

What is peripatric speciation?

A

When small groups of individuals break off from the rest of the geographic range of a species. Over time, genetic and morphological differences accumulate, causing the formation of new species.

240
Q

What is parapatric speciation?

A

When populations do not become separated by a geographic barrier, but by a colonization of a new habitat type/niche. Individuals then only mate with those in their same habitat/niche type. Over time, genetic and morphological differences accumulate, causing the formation of new species.

241
Q

Whta is sympatric speciation?

A

When there is no geographic or habitat barrier to gene flow between populations. But still over time, genetic and morphological differences accumulate, causing the formation of new species.

242
Q

How would speciation occur without a habitat or geographic barrier?

A

Cryptic species. They are morphologically similar but genetically distinct

243
Q

How do we represent the evolutionary relationships between species?

A

Phylogenetic trees

244
Q

How are phylogenetic trees built?

A

*Morphological characters
*Genetic characters
*Characters shared between the MRCA and all its descendants are synapomorphies (similar morphologies)

245
Q

What is MCRA?

A

Most Recent Common Ancestor

246
Q

What is a clade?

A

A group of organisms comprising all the descendants of the MRCA

247
Q

What is phylogeography?

A

The study of historical processes influencing the modern distribution of a species using molecular tools. It can also be used to understand genetic population divergence and speciation

248
Q

What is phenotypic plasticity?

A

When a single genome can produce more than one phenotype (e.g. morphology, life history) when exposed to different environments

249
Q

What are marine terraces?

A

They can be caused by sea-level changes caused by glacial/interglacial cycles. They can contain shell fossils, which are data points for deciphering geographic ranges due to their occurence witin the terrace

250
Q

In a geographic range, where is the biggest genetic diversity?

A

The centre population as there is often higher gene flow between populations in the range centre

251
Q

How can ecological factors be examined?

A

By examining closely related species that live in the same region (i.e. they broadly experience the same oceanographic conditions) but differ in their habitat preference, abundance, and distribution

252
Q

What is life history?

A

Life history refers to the age and/or stage specific patterns in the timing of events in an organisms life

253
Q

What is growth rate?

A

How fast an organism grows and rate of change over its life cycle

254
Q

What is the difference between determinate growth and indeterminate growth?

A

*Determinate - stop growing at a certain age (e.g. humans)
*Indeterminate - grow throughout whole life

255
Q

What different factors does life history assess?

A

*Growth rate
*Age/size of first reproduction
*Age/size of sex change
*Reproductive output and timing
*Sex ratio
*life span

256
Q

What are the life history characteristics of the Giant Pacific Octopus Enteroctopus dofleini?

A

*Grow and mature fast
*Make lots of babies
*Leave them to defend themselves after they hatch
*Very few survive to adulthood
*Die young, ~4 year life span
*Reproduce once (as mother dies as soon as eggs hatch due to lack of food whilst protecting the eggs)
*Mothers lay tens of thousands of eggs

257
Q

What are the life history characteristics of the Killer Whale Orcinus orca?

A

*Grow and mature slowly (~10-15 years old)
*Make few babies (~1 every 5 years)
*Protect them until they are fully grown
*Die of old age (>50 years old)
*Many other marine mammals have a similar life history strategy
This means they are very vulnerable to poaching and fishing pressure as they don’t recover as quickly

258
Q

What are the life history characteristics of the Sheephead Semicossyphus pulcher?

A

*All individuals start their lives as female
*Females reach maturity at ~ 4 years
*Sex change occurs at ~ 8 years old
*Age span varies by location, upwards of 50 years

259
Q

Why are some species sequential hermaphrodites?

A

*Social factors (e.g. territoriality)
*Size-advantage hypothesis: reproductive potential (i.e. chance of successful reproduction can change with size, for this species, it is more advantageous to be male when large)

260
Q

What are the two types of sequential hermaphrodites?

A

*Protrandrous - male to female
*Protogynous - female to male

261
Q

What is the life history of the Giant Owl limpet Lottia gigantea?

A

*All individuals start their lives as male
*Grow quickly and males mature at ~2 years
*Broadcast spawning once a year (winter)
*Size/age of sex change varies by location (and harvest pressure)
*Sex change occurs when territory is acquired (size-advantage hypothesis)
*Life span ~ 10-15 years

262
Q

Why do sequential hermaphrodites have skewed sex ratios?

A

Mortality increases with age so not all live to switch gender (⅔ first sex, ⅓ second sex)

263
Q

How do humans impact the life history of other organisms?

A

Size selective harvesting. Species that grow slowly and have low reproductive output are more vulnerable to human impacts

264
Q

How does maternal age impact size and survival of offspring?

A

It does not impact determinate growing species. However can impact indeterminate species as older/larger mothers produce higher quality oil globules for their larvae – which enhances their growth and survival. Older/larger mothers also produce larger, higher quality egg

265
Q

What is a coral reef?

A

Reefs are rocky marine habitats that rise from the sea bed. They are generally subtidal but may extend as an unbroken transition to the intertidal zone.

266
Q

What is the importance of reefs?

A

The cover 0.2% of the ocean but support at least 25% of all marine species. They also help provide food for humans and support the tourist industry. They can also be used as coastal buffers against storms, and the weathering of coral supplies sand to beaches.

267
Q

What is scleractinia?

A

They are Cnidaria and are stony/hard corals that help build hermatypic corals

268
Q

What are hermatypic corals?

A

*Reef building
*Contain endosymbiosis algae
*Limited to the photic zone
*Mostly found in tropical latitudes

269
Q

What are ahermatypic corals?

A

*Non-reef building
*No endosymbiosis algae
*Deep and cold water

270
Q

What is the basic structure of hermatypic coral?

A

Made of a stomach with tentacles at the top, making polyps. Each polyp is connected by tissues and are genetically identical

271
Q

What is symbiodiniaceae in hermatypic coral?

A

It is coral-algal symbiosis. The algae consume wate products produced by the coral host and uptake nutrients from seawater. They then photosynthesise to produce food and energy for the coral.

272
Q

What are the benefits of coral for the symbiodinaceae?

A

*Access to sunlight
*Stable and protected environment
*Coral metabolic waste

273
Q

Where is hermatypic coral found?

A

There is a hotspot in the ENSO-pacific region and tropics
Less diversity closer to the poles

274
Q

What are the environmental lim its for hermatypic corals?

A

*Temp = 18-36 degrees Celsius
*Latitude = 30 degrees N - 30 degrees S
*Depth = 0-30m for sunlight
*Salinity = 33-35 psu
*Wave action = high wave energy (but this has risk of storms)

275
Q

What are the different reef types?

A

*Fringing reefs
*Barrier reefs
*Atolls
*Patch reefs

276
Q

How are fringing reefs formed?

A

Volcano erupts - lava piles up on seafloor and creates a seamount which breaks the surface of the water and becomes an oceanic island. Hermatypic corals settle and begin to grow around the island = Fringing reef and grows directly out from the island

277
Q

How are barrier reefs formed?

A

Over millions of years, volcanic island erodes and sinks (subsidence) - fringing reef turns into barrier reef - farther from shore and with a deeper lagoon.

278
Q

How are atolls formed?

A

Ocean waves erode the reef and the sand piles up on the reef as island continues to sink - creates atolls = ring shaped islands.

279
Q

What is the order of coral type formation and time / vertical coral growth?

A

Fringing reef - barrier reef - atolls

280
Q

What are patch reefs?

A

They generally pop up in lagoons as hermatypic coral settles on any available substrate

281
Q

What is the Indo-West Pacific coral triangle?

A

It has very high coral diversity with other 75% of all known species. Bird’s head peninsula has 72%.

282
Q

What is competition in reefs?

A

There is limited space on reefs, and so this leads to competition over space, as well as light. There is exploitative competition over shading and interference competition with tentacles.

283
Q

What is predation in reefs?

A

*Predatory pressure is mainly chronic with sharks at the top
*There are 39 species of obligate corallivores
*The starfish Acanthaster Planck can destroy coral colonies

284
Q

What is grazing in reefs?

A

*Invertebrate herbivores: Sea urchin
*Vertebrate herbivores: Fishes, sea turtles, dugongs.
*Parrot fish (detritivores) produce coral sand

285
Q

What is the coral-algal phase shift?

A

It refers to the phenomenon of coral reefs shifting to unusually low levels of coral cover, associated with persistent states of high cover of fleshy macroalgae. This results in reduced biodiversity

286
Q

What is the intermediate disturbance hypothesis in reefs?

A

Diversity of coral in tropical reefs is a nonequilibrium state, if it is not disturbed further it may lead towards a low-diversity equilibrium community

287
Q

What are abiotic stressors in coral reefs?

A

*Pollution
*Temperature
*Hypoxia
*Ocean acidification

288
Q

What are biotic stressors in coral reefs?

A

*Prey abundance
*Predator threats
*Parasites
*Disease

289
Q

What is currently the biggest stressor for coral reefs?

A

Increasing sea surface temperature. Endosymbiotic algae is ejected from the polyp resulting in decreased growth and reproduction. This is increasing in frequency due to ENSO events and climate change

290
Q

What is the bio geographic definition of the tropics?

A

The edges of the tropics are where the geographic ranges of species found primarily within low latitudes (e.g. 0 - 25 º) come into contact with those primarily found within higher latitudes (25 º+)

291
Q

What is the difference for adaptationist for seasonality in tropical and temperate organisms

A

*Tropical species are warm adapted and there is little seasonality
*Temperate species are adapted to high seasonality

Y1 S2 (2 decks)

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