Marine ecosystems 2 (food webs) Flashcards

1
Q

Why are polar food webs simpler than boresal food webs?

A

b/c there are fewer species and less productivity

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2
Q

Arctic marine food webs are characterized by a __ food chain, high ___ content in the diets, and an apex predator of ___ ___

A

short
fat
polar bears

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3
Q

In arctic marine ecosystems, what is the main keystone species that’s connected to everyone else?

A

polar cod

  • & they rely on ice! no ice= change in entire ecosystem
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4
Q

Phytoplankton are small ___ and zooplankton are ___.

They ____ with the currents and form the ___ of the marine food chain

A

plants
animals
drift
bottom

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5
Q

What are the 2 main primary producers in arctic waters?

A

plankton- diatoms and flagellates

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6
Q

diatoms are phytoplankton that produce a ___ (__) covering

A

glass
silicate

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7
Q

Why is chlorophyll so abundant in polar waters?

A
  • lots of stored nutrients (not utilized in winter)
  • lots of sunlight in summer= they can grow quickly
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8
Q

given ongoing changes in the arctic ocean, how has primary production changed in recent years?
- was this expected?
- where has the largest change been?

A

it’s gone up! related to increase in open water season

  • not expected due to presumed limited nutrients
  • largest increases have been on the continental shelves
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9
Q

What drives primary productivity in the arctic ocean? Why?

A

sea ice melt and breakup during the spring
- b/c melt results in enhanced light avail and increased stratification and stabilization of the water column

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10
Q

t/f
phytoplankton blooms can occur beneath a ~1m thick sea ice pack, over 100km from the melt edge

why/ why not?

A

true!

maybe related to altered nutrient cycling or reduced snow cover on sea ice

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11
Q

____ can periodically limit diatom growth in the summer and fall

A

nitrogen

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12
Q

Copepods are known as the “___ of the sea” and may be the most numerous ____ animals on earth

A

insects
multicellular

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13
Q

the major consumer of marine primary production is

A

the copepods of the genus Calanus spp

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14
Q

Where do copepods spend their winter? Spring?

A

copepods overwinter at great depths (below 1000m)
Spring= they reproduce and then they all come up to surface
- spring feed allows them to accumulate a lipid-rich sac used to overwinter

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15
Q

What’s the largest species of copepod? Why is it a critical link in the arctic food web?

A

Calanus hyperboreus

b/c it eats phytoplankton/ small zooplankton in the spring
- it’s endemic to arctic waters (only lives there)

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16
Q

Amphipods are _____ that eat phytoplankton, and there are over 150 species of them in the arctic

A

crustaceans

17
Q

t/f

there are no cnidaria in the arctic ocean b/c they can’t survive in the cold waters

A

false

  • over 100 cnidarian species occur in the arctic (comb jellies, deep water medusa, arctic tube anemone, etc)
18
Q

sea ice is a complex enviro with numerous ___environments

A

microenviros

19
Q

Explain what brine channels are

A

when sea ice forms, small spaces b/w the ice crystals remain and are filled w/ brine (salty solution)
- brine channels in the sea ice form a 3D network of tubes (up to a few cm wide)
- specialized organisms live in this matrix!

20
Q

What is a sympagic community?

A

a community of organisms that lives in ice, for example within the brine channels in sea ice

21
Q

benthic fauna includes lots of ____ and ____

A

echinoderms and anemones

22
Q

macrobenthic assemblages is best explained by ___ and bottom ___

A

salinity
bottom temp

23
Q

___ ___ are a major link b/w lower trophic levels (invertebrates) and upper trophic levels (birds, mammals)

A

arctic cod

24
Q

___ are another important fish, but they’re more associated with sub-arctic than arctic waters

25
borealization= give ex
the shift from an arctic species in an area to a more temperate one ex shift from arctic cod to capelin in an area
26
Pinnipeds in the north include: (3)
- otariidae (sea lions) - Odobenidae (walrus) - Phocidae (seals)
27
walrus eat mostly ___
clams (3000-6000 of them in a single feeding!)
28
t/f pregnant polar bears can fast for up to a year
false they can fast up to 8 months
29
What are the 3 main species of arctic whales?
- bowhead whale - narwhal - belgula (white whale)
30
List the 3 key adaptations that arctic whales have
1. migrate to ice margins in the winter 2. remain in sea ice to avoid killer whale predation 3. lack dorsal fin (adaptation to break ice)
31
t/f bowhead whales declined a lot in late 1800s due to commercial whaling but the population is now recovering
true
32
changes in __-___ extent are causing shifts from traditional sympagic-pelagic-benthic web
sea-ice
33
greater area and time of open water is shifting phytoplankton blooms to __ waters, making them occur ___(earlier/ later) and reduces sympagic-benthic connection
deeper earlier
34
Which trophic level is seeing the most changes/ having the hardest time with recent sea ice and climate changes ?
top predators