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

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 20°C 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 InvertebrateBMWP Score Beetles5 Biting midge larvae2 Bivalves3 Blackfly larvae5 Cased caddisfly larvae10 Caseless caddisfly larvae7 Cranefly larvae5 Damselfly nymph8 Flatworm5 Freshwater hoglouse3 Freshwater mite0 Freshwater shrimp6

8. How to use the BMWP 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). Organism No. Found BMWP Stonefly810 Mayfly174 Hoglouse153 Total17 No. Species3 ASPT5.67