Oceans on the Edge

Threats to Coral Reefs
1. Global Warming
  1. warmer oceans= algae unable to survive
    1. Leads to coral bleaching which upsets the cycle of coral
2. Fishing
  1. Blast fishing
    1. Some fishing methods are purely destructive such as using explosives
  2. For Aquariums
    1. upsets food web unless carefully controlled
    2. Many tropical countries poor + fish is part of diet
      1. Population increase=added pressure
3. Coastal Development
  1. Increased sediment in rivers
  2. Disturbed ground
  3. Erosion of loose soil
  4. Pollutants into water
4. Tourism
  1. major income source
  2. water skiing, scuba diving + surfing cause disturbance
  3. Resorts increase pollutants in lagoons
Affects of Overfishing on food webs
1. Whales hunted, populations falling fast
2. Affects population of fish + animals dependant on them
3. Krill
  1. In demand for high protein value
  2. Krill live off phytoplankton
    1. consume CO2, produce half world's oxygen output
How Marine Food Webs are Disturbed
1. Eutrophication
  1. Mainly caused by overuse of fertilisers
  2. Too many nutrients in marine systems cause extreme algae growth
    1. This blocks sunlight + removes oxygen from water
      1. This damages coral reefs
        In extreme cases, creates oxygen-depleted zones - 'dead' zones
2. Siltation
  1. Happens when silt settles onto marine ecosystems
    1. Sources of silt
      1. erosion of farmland
      2. deforestation
      3. Urban Development
  2. Silt enters sea via rivers
    1. blocks out sunlight
      1. marine plants can't photosynthesise
        Can also smother seabed, destroying seafloor habitat
Contribution of Climate Change
1. Warming
  1. Coral Bleeching
    1. algae in coral are expelled so coral dies and turns white
  2. Species Migration
    1. Cold water loving species like cod migrate to new areas
      1. Disrupts fishing
2. Sea-level rise
  1. Changing light levels
  2. Coastal flooding
3. Acidification
  1. Coral and shellfish health
    1. Calcium carbonate dissolves in acid water, shells + skeletons become weaker + harder to grow
Soufriere Bay, St Lucia
1. Local pressures
  1. Growing Population
  2. Tourism
  3. Runoff and waste
  4. Fishing
2. Conflicting Views
  1. Local fishermen
    1. Want to continue to fish + satisfy demand from tourists
      1. Damaging + unsustainable fishing will reduce fish supply
      2. Fishermen + tourists often use the same areas of reef
  2. Tourists
    1. Want a pristine reef
      1. High numbers of tourists could damage ecosystem
  3. Yacht owners + cruise ships
    1. Need space to offload tourists
      1. Waste thrown overboard, oil spills damage reefs
  4. Local businesses
    1. depend on tourism
      1. want sea + reef kept natural + pristine to encourage tourists
        More tourists=more damage
3. SMMA
  1. Brought different groups together to resolve conflicts
  2. Zoned the bay, conflicting activities given separate areas of bay
  3. Marine reserves -off-limits to everyone
  4. Locals trained to police the area
  5. Tourist taxes used to pay for managements
North Sea, Northern Europe
1. EU common fisheries policy aims to conserve fish stocks
2. Quotas
  1. Restrict catches
  2. Restrict number of fishing boats
3. UK have fishing patrol boats, checking catch numbers
4. EU agreed to reduce dead fish catches
5. 'No-take zones' introduced (fishing is banned)
6. On-going Problems
  1. Fishing is not yet sustainable
  2. Cod, haddock and whiting still need to recover
  3. More, larger no-take zones are needed
  4. Difficult to resolve issues between fishers, consumers + environment
    1. Fishers need Income
    2. Environ. needs sustainability
    3. Consumers need fish

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Oceans on the Edge

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