Transcript Slide 1

BTEC
Freshwater
Ecology
Assignment
Interdependence
All members of an ecosystem are connected in a
network of relationships
The success of the whole system depends on the
success of its individuals
The success of an individual depends on the
success of the system as a whole
Pollution
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Litter?
Noise?
Greenhouse gases?
Acid rain?
Housing development?
Eutrophication?
Sewage?
What is pollution?
‘The addition of a substance or
energy by human activity to an
ecosystem which upsets its
natural balance.’
Eutrophication
Nitrates and phosphates
enter freshwater
Species diversity is
reduced
(from organic or inorganic source)
Increase in nutrient
content causes rapid
plant/algae growth
Plants/algae die
Bacteria feed on
decaying plant material
Tolerant species number
increase
Oxygen sensitive species
die
Respiration from
bacteria reduces oxygen
content of water
BOD
• Biological Oxygen Demand
• ‘a measure of oxygen used by micro-
organisms decomposing organic matter’
• Measure dissolved oxygen in sample
• Keep in dark at 20°C for 5 days and
measure dissolved oxygen again
BMWP
• Invertebrates need
oxygen
• Some need more than
others:
– Breathing adaptations
– Suitability for lower
oxygen
– Score reflects this
Invertebrate
BMWP
Score
Beetles
5
Biting midge larvae
2
Bivalves
3
Blackfly larvae
5
Cased caddisfly larvae
10
Caseless caddisfly larvae
7
Cranefly larvae
5
Damselfly nymph
8
Flatworm
5
Freshwater hoglouse
3
Freshwater mite
0
Freshwater shrimp
6
How to use the BMWP
1.
2.
3.
4.
List the organisms
present in the sample.
Give each organism a
score according to the
BMWP scoring system.
Sum the scores to give a
total score for the site.
Divide the BMWP score
by the number of
species to give the
ASPT (average score
per taxon).
No.
Found
Organism
BMWP
Stonefly
8
10
Mayfly
17
4
Hoglouse
15
3
Total
17
No. Species
3
ASPT
5.67