 |
 |
||
|
|||
Activity 4: Making Marine Habitat Maps
Background: Shallow Water Habitat Mapping Mapping the shallow sections of Victoria’s Marine National Parks and Marine Sanctuaries is done using aerial photographs taken under good conditions. In Victoria under specific environmental conditions (which include a low tide, clear water, a shallow sun angle (so as not to reflect too much sun off the water’s surface) and little wind) it is possible to use an aerial photograph to look at the sea floor in water less than about 10 metres deep. When you get such a photo (which can take a lot of planning and waiting for the right day) many features on the sea floor are visible and detailed maps can be made by carefully identifying the different features within the park. |
 Aerial photograph of Barwon Bluff Marine Sanctuary Click photo for larger version |
By comparing the aerial photographs with video and photographs taken at known points within the park scientists can further develop the maps by accurately identifying the main habitats found in the park.
Deep Water Habitat Mapping
Because of the water clarity and usual light conditions in Victoria, for deeper sections of the parks (below about 10 metres) aerial photography is not very useful for habitat mapping. In the Marine Mapping Project multibeam sonar was used to map deeper sections and has provided an enormous amount of information about the parks, much of which was previously unknown.
Multibeam sonar images not only provide information about the depth and help create three dimensional images but can also be used to predict what types of marine habitats are found there. The way that sound waves are reflected from the seabed varies according to what type of material on the bottom. Rocks will reflect differently to sand, and these will be also influenced by living things like kelp forests. By analysing differences in the reflected signal, texture images of the park can be created that identify the different materials. By comparing actual pictures collected through video surveys and photographs with the different textures seen on the multibeam image, scientists can identify where the different habitats are found in the park and generate a habitat map to show this. |
 Post 2005 Habitat map of Point Addis Marine National Park Click map for larger version |
Next - How Habitat Maps are made
 |
 |
 |
| Copyright © Parks Victoria 2006 | ||