environmental gradients Flashcards

1
Q

what are examples of environmental gradients?

A

• particle size
• salinity
• vertical: emersion/depth
• wave exposure
• latitude/temperature
• anthropogenic disturbance

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2
Q

what life is present on rocky shores?

A

epifauna and flora

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3
Q

what life is present on cobbles and shingles?

A

unstable and lifeless, no macrobiota

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4
Q

what life would be present in salt marshes, mangroves, seagrasses and sandy beaches?

A

infauna, epifauna and macrophytes

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5
Q

What adaptations would be present in plants in anoxic sediments?

A

Prop roots - enable gas exchange out of sediment using lenticels

Pneumatophores – roots that stick up out of surface and do gaseous exchange

MANGROVES IN MUDDY SHOREs

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6
Q

What are halophytes?

A

Plants adapted to growing in saline conditions, e.g. mangroves in muddy shores or terrestrial plants in salt marshes

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7
Q

What is true of mangroves in muddy shores?

A

Serves as coastal erosion protection

Sediment accretion

Infaunal communities present

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8
Q

What are infaunal communities?

A

Aquatic animals that live in the substrate of a body of water and which are especially common in soft sediments

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9
Q

What is true of sandy beaches?
(in terms of sediment)

A
  • Physical substrate is shifting and unstable
  • Substance disturbance by waves
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10
Q

What is true for fauna on sandy beaches?

A
  • Burrow to avoid stresses and predation
  • Fauna rely on imported food
  • Low primary production
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11
Q

What is the intermediate disturbance hypothesis?

A

Predicts that the highest diversity will occur at levels of moderate disturbance.

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12
Q

What are Sousa’s (1979) notes on the intermediate disturbance hypothesis?

A

Size of boulders, mobility and their diversity – boulders with intermediate disturbance had highest number of species

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13
Q

What are Connell’s (1978) notes on the Intermediate disturbance hypothesis?

A

Low or high diversity is bell shaped from frequent and rare, large or small, etc.

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14
Q

What is true of rocky shores?

A
  • Physical substrate is hard and stable
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15
Q

What is true of fauna on rocky shores?

A
  • Organisms visible
  • Living on top of substrate: epifauna, epifloral, not to be confused with epibiont
  • Abundant and small – unusually large specimens on West Coast of USA
  • Sessile or sedentary
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16
Q

What is a fully stratified salinity gradient?

A

Fresh water flows over seawater

17
Q

What is a moderately stratified salinity gradient?

A
  • Wind
  • Tide mixing
  • River water begins to mix
  • Wedges formed
18
Q

What is a vertically homogenous salinity gradient?

A

Zones gradually become saline

19
Q

What is true of estuaries salinity regime?

A

Variable salinity regime

20
Q

What is the flow of estuaries?

A

Fresh -> river, head, upper reaches, middle reaches, lower reaches, mouth -> marine

21
Q

What is true of the biodiversity of estuaries?

A
  • Few true estuarine species (complete whole life cycle)
  • Many visitors (anadromous/catadromous)
22
Q

What are some adaptations of estuarine species?

A
  • Osmoconformers - Adapt to salinity of local environment as it changes
  • Osmoregulators - internal processes to regulate own salinity of body, don’t take on local salinity regime
23
Q

What is an example of the broader biogeographic impacts of freshwater input?

A

– Yangtze River Plume:

–– Genetic differences present for 3 rocky shore limpet species between the Yellow Sea and other 2 marginal seas (East China Sea and South China Sea)

–––– No difference for muddy shore species Atrina pectinate (salt marsh around estuary)

24
Q

What does the vertical gradient represent?

A

Shallow subtotal to intertidal to terrestrial

25
Q

What are the zonations of coral reefs?

A

Sea, reef, slope, reef crest, buttress zone, reef flat, lagoon, beach

26
Q

What are the zonations of mangroves?

A

terrestrial forest, landward zone, mid zone, seaward zone, sea

27
Q

What is true of the wave exposure gradient?

A
  • Waves horizontal across shoreline
  • Wave energy converges on headland
28
Q

What is the ballentine exposure scale?

A

Scheme uses biology of the shore itself to define was exposure. Used to represent an integration of exposure conditions over long time scales

– 8-point scale: 1= highly exposed, 8= very sheltered

29
Q

What is true of the latitudinal gradient of seagrasses?

A
  • Global distribution
  • Relatively few species (12 genera, 60 sp.)
  • High biodiversity in south East Asia, decreasing towards poles