Oceans on the Edge

Oceans on the Edge

1. Threats to Coral Reefs

   • Global Warming
     • warmer oceans= algae unable to survive
       • Leads to coral bleaching which upsets the cycle of coral
   • Fishing
     • Blast fishing
       • Some fishing methods are purely destructive such as using explosives
     • For Aquariums
       • upsets food web unless carefully controlled
       • Many tropical countries poor + fish is part of diet
         • Population increase=added pressure
   • Coastal Development
     • Increased sediment in rivers
     • Disturbed ground
     • Erosion of loose soil
     • Pollutants into water
   • Tourism
     • major income source
     • water skiing, scuba diving + surfing cause disturbance
     • Resorts increase pollutants in lagoons

2. Affects of Overfishing on food webs

   • Whales hunted, populations falling fast
   • Affects population of fish + animals dependant on them
   • Krill
     • In demand for high protein value
     • Krill live off phytoplankton
       • consume CO2, produce half world's oxygen output

3. How Marine Food Webs are Disturbed

   • Eutrophication
     • Mainly caused by overuse of fertilisers
     • Too many nutrients in marine systems cause extreme algae growth
       • This blocks sunlight + removes oxygen from water
         • This damages coral reefs
           • In extreme cases, creates oxygen-depleted zones - 'dead' zones
   • Siltation
     • Happens when silt settles onto marine ecosystems
       • Sources of silt
         • erosion of farmland
         • deforestation
         • Urban Development
     • Silt enters sea via rivers
       • blocks out sunlight
         • marine plants can't photosynthesise
           • Can also smother seabed, destroying seafloor habitat

4. Contribution of Climate Change

   • Warming
     • Coral Bleeching
       • algae in coral are expelled so coral dies and turns white
     • Species Migration
       • Cold water loving species like cod migrate to new areas
         • Disrupts fishing
   • Sea-level rise
     • Changing light levels
     • Coastal flooding
   • Acidification
     • Coral and shellfish health
       • Calcium carbonate dissolves in acid water, shells + skeletons become weaker + harder to grow

5. Soufriere Bay, St Lucia

   • Local pressures
     • Growing Population
     • Tourism
     • Runoff and waste
     • Fishing
   • Conflicting Views
     • Local fishermen
       • Want to continue to fish + satisfy demand from tourists
         • Damaging + unsustainable fishing will reduce fish supply
         • Fishermen + tourists often use the same areas of reef
     • Tourists
       • Want a pristine reef
         • High numbers of tourists could damage ecosystem
     • Yacht owners + cruise ships
       • Need space to offload tourists
         • Waste thrown overboard, oil spills damage reefs
     • Local businesses
       • depend on tourism
         • want sea + reef kept natural + pristine to encourage tourists
           • More tourists=more damage
   • SMMA
     • Brought different groups together to resolve conflicts
     • Zoned the bay, conflicting activities given separate areas of bay
     • Marine reserves -off-limits to everyone
     • Locals trained to police the area
     • Tourist taxes used to pay for managements

6. North Sea, Northern Europe

   • EU common fisheries policy aims to conserve fish stocks
   • Quotas
     • Restrict catches
     • Restrict number of fishing boats
   • UK have fishing patrol boats, checking catch numbers
   • EU agreed to reduce dead fish catches
   • 'No-take zones' introduced (fishing is banned)
   • On-going Problems
     • Fishing is not yet sustainable
     • Cod, haddock and whiting still need to recover
     • More, larger no-take zones are needed
     • Difficult to resolve issues between fishers, consumers + environment
       • Fishers need Income
       • Environ. needs sustainability
       • Consumers need fish

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