The thrombolites Lake Clifton in Yalgorup National Park are about 100km south of Perth. These rock-like structures, a form of microbialite, occur in rocky clumps which look similar to the famous strombolites found within Shark Bay’s Hamelin Pool, some 800km north of Perth.
Strombolites are examples of one of the earliest forms of bacterial life presently known to man and reside in salty water. Thrombolites, on the other hand, grow best in fresh water. The bacteria within them are photosynthetic and create calcium carbonate which is basically what limestone is made of. Apparently, the largest known population of living marine microbialites in the southern hemisphere are found at Lake Clifton in Yalgorup National Park. They require fresh water and monitoring of Lake Clifton’s fresh water is highlighting a decline in fresh water run off to the lake. There are other populations in nearby Lake Preston and further south in Augusta and Esperance.
Thrombolites are at risk by increasing water salinity, which stops them growing. Water salinity at Lake Clifton is affected by reduced fresh water run off from climate change and groundwater changes from urban and agricultural uses.
The day I made these photographs of Lake Clifton Thrombolites Yalgorup Mandurah I took my metal wista 4×5 field camera with 4×5 sheet film and a 6×12 film back. (The Horseman 6×12 back is quite thick and puts pressure on the ground glass springs of my wooden field camera). The film stock I was using for both was 50ISO Velvia. I timed my arrival for the mid to late afternoon, giving myself time to scout for potential compositions, although on an earlier visit I had already decided on a dusk composition (pictured above).
With the setting sun, the trees and reeds fringing Lake Clifton were lit with a warm orange light and the shapes of the thrombolites stood out in high contrast against the water. Using the reach of a longer focal length lens the 6x12cm back allowed me to fill the frame with thrombolites and the lake’s edge. It also allowed me to create several exposures in close succession, each one being a potential in camera duplicate should one be damaged by the handling of a publisher.
The image above was a timed exposure of several seconds made on 4×5 film after the sun had set. One of Velvia’s characteristics with long exposures is to develop a purplish magenta colour cast.
Lake Clifton Thrombolites Yalgorup National Park has been published in the 2015 Australian Conservation Foundation Diary. By purchasing it directly from Rob Blakers’ web site you can support the Australian Conservation Foundation and enjoy a yearly supply of wonderful photographs of Australia’s national parks.