Science Centres: Oceans

It sounds easy, but equipment and vessel time as well as unpredictable weather make it time consuming and expensive to map the seafloor using cameras alone.

At NIWA, we have developed a quicker, more cost effective method. First we acoustically map the seafloor using technology such as sidescan or multibeam sonar. We use the acoustic images, and our ecological experience, to guide where we deploy video cameras. Once we have the video footage, we use statistical techniques and ecological information on the importance of various species to classify the observations into habitat types. We can pinpoint the location of the habitats to within less than a metre using differential GPS.

We recently used these techniques to map the ecological habitats in and around Te Angiangi Marine Reserve, south of Napier, for the Department of Conservation. We found the rocky reefs in the area were often covered with pink coralline algae, large brown algae, sponges, sea squirts, and other creatures. The abundance of each species changed with depth. By contrast, not many organisms lived on the sandy sediments in the area, because they were much more exposed to waves. In other parts of the country, however, we often see worm tubes, algae, snails, shellfish, sponges, and bryozoans, as well as evidence of shrimps and crabs.