chalk streams Flashcards

1
Q

what is a chalk stream?

A

habitat and ecology or perennial chalk stream headwaters and future challenges.

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2
Q

what gradient do chalk streams have and why?

A

low gradient, due to them forming from ocean beds, they’re very erodable.

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3
Q

what percentage of the annual discharge may derive from groundwaters?

A

90%

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4
Q

what is the temperature like in chalk streams?

A

relatively constant at around 11 degrees if a spring.

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5
Q

what is the hydrology and flow like in a chalk stream?

A

relatively persistent hydrology and flow with dampened discharge fluctuations.

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6
Q

what is the ratio between hydrology and flow?

A

3:1

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7
Q

why are floods rare in chalk streams?

A

due to the large storage capacity.

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8
Q

what is the substratum dominated by and why?

A

gravel, due to the geology, pebbles and gravel are sensitive to siltation, because of the low gradient and placid flow.

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9
Q

what temperature are chalk rivers?

A

around 5-17 degrees.

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10
Q

what are natural influences in chalk rivers?

A

feedback between organisms and the physical environment.

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11
Q

how does a protected area influence chalk streams?

A

the flow is altered due to organisms.

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12
Q

what are human influences on chalk streams?

A

structures such as mills, damns, ponds, drains, diches, and food defences.

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13
Q

what river and bank managements are put into place to protect chalk rivers?

A

weed cutting, bank protection, rehabilitation, bank poaching, runoff from agriculture, and water abstraction.

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14
Q

how does weed cutting protect the chalk rivers?

A

it makes it harder to fish due to the barrier and hydraulic resistance. if there is a lot of weeds, it will slow the water down and cause localised flooding.

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15
Q

why is bank protection important?

A

ensure they’re maintained, no eroding towards houses.

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16
Q

what is bank poaching?

A

when animals go into the water to drink or cool down and it causes the banks to erode away.

17
Q

how many of England’s rivers are altered?

A

95% of all rivers in England are altered.

18
Q

if we change one element of the chalk system, what effect does this have?

A

bottom-up- limited top. top-down- influences the whole structure. food webs and trophic interactions may get altered.

19
Q

a question to think about: is there a predominance of generalist or specialist feeders?

A

?

20
Q

a question: can we diagnose the causes of past changes and can we predict the impact of contemporary change?

A

?

21
Q

a question: can we use science to underpin decisions for the future?

A

?

22
Q

what will happen if a tree was put above the river?

A

there will be fewer algae, therefore this will affect the primary consumers.

23
Q

which level will be completely affected if algae decrease?

A

the primary consumers, but only if that is their main food source or only food source.

24
Q

how do you know if a chalk stream is meeting expectations?

A

if you know what to expect to do with eh conditions and the number of species.

25
Q

what species influence chalk rivers?

A

bird species

26
Q

what is important for chalk rivers and why?

A

specific hydraulic conditions and local channels. this is due to the local conditions.

27
Q

what is the Biota within each headwater stream influenced by?

A

local conditions, habitats, environmental conditions and ecology.

28
Q

what percentage of the world’s chalk stream resources are found in England?

A

85%

29
Q

what are the conservation goals for chalk rivers?

A

protection, enhancement of rare or threatened species.

30
Q

what are the ecosystem’s service goals for chalk rivers?

A

recreation, amenity, water resources.

31
Q

what are human use goals for chalk streams?

A

economics, socal and other benefits.

32
Q

how many of the rivers are protected?

A

out of 224 streams, only 12 are protected.

33
Q

what percentage of chalk rivers and classes as adequately protected and meeting conservation targets?

A

15%

34
Q

what species is making a come-nack with increased observed nationally?

A

otters!