Journal of Insect Conservation

, Volume 17, Issue 1, pp 147–153 | Cite as

The impact of cave lighting on the bioluminescent display of the Tasmanian glow-worm Arachnocampa tasmaniensis

  • David J. MerrittEmail author
  • Arthur K. Clarke


Bioluminescent larvae of the dipteran genus Arachnocampa are charismatic microfauna that can reach high densities in caves, where they attract many visitors. These focal populations are the subjects of conservation management because of their high natural and commercial value. Despite their tourism importance, little is known about their susceptibility and resilience to natural or human impacts. At Marakoopa Cave in northern Tasmania, guided tours take visitors through different chambers and terminate at a viewing platform where the cave lighting is extinguished and a glowing colony of Arachnocampa tasmaniensis (Diptera: Keroplatidae) larvae on the chamber ceiling is revealed. Research has shown that exposure to artificial light can cause larvae to douse or dim their bioluminescence; hence, the cave lighting associated with visitor access could reduce the intensity of the natural display. We used time-lapse digital photography to record light output over 10 days to determine whether cave lighting affects the intensity or rhythmicity of bioluminescence. Simultaneously, another colony in a different section of the cave, away from tourist activity, was photographed over 3 days. Both colonies showed high-amplitude 24 h cycling of bioluminescence intensity, with the peak occurring at 11.50 h at the unvisited site and 12.50 h at the main chamber, so the time of peak display did not appear to be substantially affected by light exposure. Intermittent light exposure experienced by larvae in the main chamber caused detectable reductions in bioluminescence intensity; however, recovery was rapid and the overall shape of the daily bioluminescence curve closely matched that of the unvisited colony. In conclusion, the artificial light exposure regime used in Marakoopa Cave does not have a substantial effect on the timing or quality of the bioluminescence display. The time-lapse photographic monitoring method could be permanently implemented at focal tourism sites to provide information about daily, seasonal and annual fluctuations in the displays, the response to events such as drought and flood, and the population’s ability to recover from adverse conditions.


Tourism Glow-worm Arachnocampa tasmaniensis Monitoring Circadian rhythms 



We thank Cathie Plowman for help in installing and collecting the camera equipment. We thank Mike Driessen, Paul Flood and Robert Buck of Department of Primary Industries, Parks, Water and Environment, Tasmania for providing cave access, information on lighting and light intensities, permits and accommodation and Rolan Eberhard of Department of Primary Industries, Parks, Water and Environment, Tasmania for discussions, suggestions and encouragement. We thank Joel Levine for providing Matlab functions used in signal analysis.


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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  1. 1.School of Biological SciencesThe University of QueenslandBrisbaneAustralia
  2. 2.School of ZoologyUniversity of TasmaniaGPO HobartAustralia

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