| There have been many types of Ecological | | | | the government. Guppies got into a system of |
| disaster. In this article, I am going to confine | | | | underground waterways in Western Australia. |
| myself to disasters caused to Australian | | | | These have decimated the native fish adapted to |
| Ecosystems by introducing other animals. | | | | this environment. Aquarists need to be very |
| The most famous one was the introduction of | | | | careful to not release any of their fish into |
| the Rabbit. The Rabbits in Australia are mostly | | | | waterways. They also need to be aware that |
| descended from a deliberate introduction of a | | | | unexpected things can happen. Ponds can |
| group of wild Rabbits in Victoria in south eastern | | | | overflow. Normally we would not expect fish to |
| Australia. These were released in the hope of | | | | be able to get out of an aquarium into natural |
| starting a business selling rabbit skins. | | | | rivers, but a friend of mine had a very nice Oscar. |
| This did actually happen, but there was nothing to | | | | A sudden flood came. My friend, together with his |
| stop the rabbits spreading to the rest of mainland | | | | wife and baby spent the night on top of their |
| Australia. Now we have billions. They compete | | | | house while the water flowed through their house. |
| with the native animals, denude the landscape of | | | | Their Oscar went out with the water. In this case, |
| vegetation and severely reduce the potential | | | | the fish would not have survived. It would have |
| carrying capacity of the land for grazing animals | | | | been swept out to sea and died, but there must |
| like sheep and cattle. | | | | be cases where this type of unexpected event |
| After doing this to the mainland, some early | | | | does put fish into waterways they can survive in. |
| settlers actually introduced rabbits to Kangaroo | | | | A ridiculous introduction was the fox. They were |
| Island. On Kangaroo Island they were killed off by | | | | brought to Australia so the upper class English |
| the goannas which went down the rabbit burrows | | | | who were coming to Australia could enjoy their |
| and ate the babies. On the mainland rabbits also | | | | fox hunting. |
| had predators, but one of the main ones, the | | | | Not all introductions have been disastrous. The |
| Wedge-tailed Eagle, was killed off in huge numbers | | | | Prickly Pear Cactus got into the state of |
| in the mistaken belief that they kill lambs. | | | | Queensland where it was spreading at an |
| As well as the disasters caused to land | | | | enormous rate. (The prickly Pear was introduced |
| ecosystems there have been ones in the water. | | | | by the British Government with the first fleet.) A |
| The most obvious one was the deliberate | | | | moth was introduced, with the very descriptive |
| introduction by the government of European Carp | | | | name; Cactoblastis cactorum. The caterpillars of |
| to the River Murray. The Murray-Darling River | | | | this moth totally devastated patches of the |
| system is by far the most extensive in Australia. | | | | invasive weed in tropical areas. It was not |
| The carp were introduced to eat the weeds | | | | effective in cooler areas, but remains one of the |
| growing in the river. Now they have taken over | | | | most spectacular examples of biological weed |
| much of the river's ecosystem and severely | | | | control. |
| reduced the numbers of native fish. | | | | Another government attempt at biological control |
| There are many other examples of introducing | | | | was the introduction of the Cane Toad, Bufo |
| other fish and totally disrupting aquatic | | | | marinus, to control beetles in sugar cane. They |
| ecosystems. One I have personally observed was | | | | failed to control the beetles and are now |
| the extinction of the Lake Eacham Rainbow fish. | | | | spreading steadily through Australia, disrupting |
| In almost every little waterway in my area there | | | | ecosystems as they go. |
| are to be found numbers of Mosquito Fish (mostly | | | | Not all destructive introductions in Australia were |
| Gambusia affinis). These were introduced by the | | | | of foreign species. There are several cases of |
| government to control Mosquitoes. Recent | | | | native Australian Animals being taken to different |
| research suggests that they are not even | | | | places in Australia and causing destruction. Koalas |
| particularly good at this, and the large numbers of | | | | were introduced to Kangaroo Island and increased |
| native species were already controlling Mosquitoes | | | | to such an extent that they are killing off the |
| very well. Now it is illegal to even possess | | | | Manna Gum trees. |
| Mosquito fish. | | | | There are large numbers of other examples of |
| Of course, not all the introductions were done by | | | | deliberate introductions that have caused havoc. |