5. Human Process Threatening the Broads Eutrophication is a process that is caused by human action (farming and sewage). It literally means ‘The Process of Making Too Much Food’. Eutrophication
6. Human Process Threatening the Broads Stage 1 Farmer puts fertilisers (NITRATES) on farmland to help crops to grow. PHOSPHATES from human waste are discharged straight into the Broads from sewage works.
7. Human Process Threatening the Broads Stage 2 Rain falls onto farmland and washes the nitrates into the broads. Phosphates from treated sewage is released into the broadland ecosystem.
8. Human Process Threatening the Broads Stage 3 Both the nitrates and phosphates serve as a rich source of nutrients for plant life and especially algae. They multiply and die very quickly. The broads become covered in "algal blooms", where the top of the water is completely covered in algae.
9. Human Process Threatening the Broads Stage 4 The accelerated growth of algae means that the oxygen levels in the water decrease rapidly, and the "algal blooms" block out the sunlight. This causes the death of many plants and animals.
10. Human Process Threatening the Broads Stage 5 The huge numbers of algae die quickly and accumulate on the bed of the broad. The material formed is necron mud which continues to consume oxygen as it rots. This also fills up the broad, making it shallower.
11. Human Process Threatening the Broads Stage 6 If this process is allowed to continue, the broad will eventually fill up with necron mud and disappear. In addition, tourist boats in the area can stir up the necron mud, which is rich in nutrients, which means the process of eutrophication is continued.
12. Human Process Threatening the Broads Stage 7 Eventually the broad disappears completely, infilled by necron mud and dead animals. Vegetation succession then takes over the area. This process can be stopped.
13. Nutrients washed off into the broads from farming - sewage To many nutrients + sunlight = excessive growth of algae Algea block out the sunlight and this kills the low water plants Nutrients – phosphorus and nitrogen from decomposing swamp washed of into water in 1800 Sunlight Weeds replace the low water plants This creates suitable environment for fish
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16. Vegetation Succession Natural Process Threatening the Broads Vegetation Succession is a natural process where dead plants lower the water level and plants infill the Broads.
17. Natural Process Threatening the Broads Vegetation Succession Large body of open water Vegetation grows in a specific order at the edge Peat from dead plants STAGE 1
18. Natural Process Threatening the Broads Vegetation Succession Vegetation grows further into the broad Amount of water in the broad decreases A new layer of peat builds up from dead plants STAGE 2
19. Natural Process Threatening the Broads Vegetation Succession STAGE 3 The inevitable end to the whole process is that the broad completely fills up and FEN CARR (woodland) takes over. The whole process only takes 20 years.
