BTEC

1
BTEC

• Freshwater Ecology
• Assignment

2
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
3
Pollution

• Litter?
• Noise?
• Greenhouse gases?
• Acid rain?
• Housing development?
• Eutrophication?
• Sewage?

4
What is pollution?

• The addition of a substance or energy by human
  activity to an ecosystem which upsets its natural
  balance.

5
Eutrophication
Nitrates and phosphates enter freshwater (from
organic or inorganic source)
Species diversity is reduced
Tolerant species number increase
Increase in nutrient content causes rapid
plant/algae growth
Oxygen sensitive species die
Plants/algae die
Respiration from bacteria reduces oxygen content
of water
Bacteria feed on decaying plant material
6
BOD

• Biological Oxygen Demand
• a measure of oxygen used by micro-organisms
  decomposing organic matter
• Measure dissolved oxygen in sample
• Keep in dark at 20C for 5 days and measure
  dissolved oxygen again

7
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
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How to use the BMWP
Organism No. Found BMWP
Stonefly 8 10
Mayfly 17 4
Hoglouse 15 3
Total 17
No. Species 3
ASPT 5.67

1. List the organisms present in the sample.
2. Give each organism a score according to the BMWP
   scoring system.
3. Sum the scores to give a total score for the
   site.
4. Divide the BMWP score by the number of species to
   give the ASPT (average score per taxon).