In previous blog posts, we have talked about sensitive plants that act as bioindicators that could potentially detect pollutants like ozone in the in Switzerland (links from previous blog post: Plants as bioindicators of ozone and Effect of Ozone On Native Plant Species in Switzerland). In Singapore, we also have natural bioindicators like insects and lichens. This blog post is going to touch on lichens as a bioindicator that monitors atmospheric pollutants.

 

Lichen is an organism that consists of a symbiotic relationship between a photosynthetic algae and two or more fungi. They are usually found living on the surface of living or non-living things. Lichens absorb nutrients via the deposition of atmospheric particulate, hence, they absorb any particle that lands on them. This characteristic results in them readily bioaccumulating particles from the atmosphere, including heavy metals (Ng et al., 2006). They are particularly sensitive to sulfur dioxide as the compound destroys the chlorophyll pigments of the algae component of lichens (Choong, 2020).

 

 

In a research done by Ng et al. (2006), Dirinaria picta, a species of lichen in Singapore were examined at six different sites across Singapore for heavy metal pollution. Pollutants found include arsenic, cadmium, copper, nickel, lead, and zinc. The research also concluded that Singapore had a relatively high concentration of heavy metals accumulation within lichens as compared to other temperate countries (Ng et al., 2006). Hence, such bioindicators may be potentially helpful in determining pollutant levels in Singapore’s atmosphere, and it may also be used to study and track changes in pollutants overtime, by examining these organisms.

 

References

Choong, M. F. A. (2020). Waste impact on ecosystems (I) [PowerPoint slides]. Unpublished manuscript, LSM1307 Waste and our Environment, National University of Singapore, Singapore

Ng, O. -., Tan, B. C., & Obbard, J. P. (2006). Lichens as bioindicators of atmospheric heavy metal pollution in singapore. Environmental Monitoring and Assessment, 123(1-3), 63-74. doi:10.1007/s10661-005-9120-6