As part of PHCC’s National Landcare Program Wetlands and People project the thrombolite community at Noorook Yalgorap (Lake Clifton) will be carefully assessed over the next few years. To help manage any population of plants or animals, one of the key pieces of information that you need to know is: How many do we have and where are they? Thrombolites are no different, so to answer these basic questions PHCC recently engaged Spectrum Ecology to carry out an aerial survey of the lake. With lake levels low at this time of year, the high resolution photography will be used to carefully map the entire thrombolite population.
The photography was taken from a low-flying aircraft but in order for the resulting images to be of value in terms of mapping, they need to be imported into computer mapping software along with spatial information that will tell the software exactly where the images were taken. The process is called “georeferencing” and involves establishing several Ground Control Points with known latitude and longitude that can be clearly seen in the aerial photography. The mapping software is then given these locations and from this the whole photographic set can then be aligned with the correct co-ordinates. In the photo Chris Parker and Chris Shaw have pegged the marker at a location next to the lake that will be clearly visible from the air. The GPS equipment they are using provides very accurate location information.
The photography will be compared to thrombolite mapping that was done in the late 1980s to see if there’s been any changes or if any populations exist that weren’t picked up in the past. In addition, we also took photographs in the near-infrared spectrum, which is invisible to the human eye but can detect photosynthetic activity. It is hoped that this remote-sensing technique can be used to pick up the difference between “active” and “inactive” thrombolites so we can make an assessment of the change in the health of the thrombolites over time.