What humans have done that has affected the Galapagos islands

Jelly Bean
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Jelly Bean
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a2 biology f215 humans and the galapagos

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What humans have done that has affected the Galapagos islands
  1. Habitat disturbance
    1. Increased pollution, building & convertionof land for agriculture have caused destruction and fragmentation of habitats
      1. Forests of Scalesia trees and shrubs have been almost eradicated on Santa Cruz & San Cristobal for agricultural land
        1. Exponential increase of human population
          1. increases demands on water, energy & sanitation services which authorities struggle to meet.
            1. More waste pollution produced and oil demands have increased
          2. Over-exploitation of resources
            1. In C19 whaling boats & fur - traders took up residence, harvesting whales & seals to sell internationly
              1. Species were harvested faster than they could replenish themselves
              2. Giant tortoises were take as they could survive on little food whilst in ships for long periods of time, before being killed & eaten
                1. This lead to plummeting number of tortoises (over 200K in less than 1/2C
                2. Depletion of sea cucumber populations has a drastic effect on under-water ecology.
                  1. International market of shark fin has led to 150K sharks each year around the islands (includes 14 species listed as endangered)
                  2. Introduced species
                    1. Species such as: goats, cats, fruits & vegetable plants were deliberately brought to the islands. Other species like insects were carried accidently.
                      1. These species out-competed local species, alien species can eat native species & destroy native species' habitats, and bring diseases such as: avian malaria & bird flu
                        1. Goats
                          1. Most damaging species to Galapagos ecosystem as it eats Galapagos rock purslane
                            1. It out-competes the giant tortoise for grazing, trampling & feeding on their food supply & changes the habitat to reduce the number of tortoise nesting site
                              1. On Northern Isabella island the goat has also transformed forest into grassland, leading to soil erosion
                              2. Cats
                                1. Hunt species like lava lizard & young iguanas
                                2. Red quinine tree
                                  1. The red quinine also out competes native Scalesia trees
                                    1. The Cacaotillo shrub has almost been eradicated from Santa Cruz
                                      1. On Santa Cruz the red quinine tree is aggressively invasive. Occupying high lands, spreads rapidly, has wind dispersed seeds. Highland ecosystem has changed from low shrub & grassland to closed forest canopy
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