Epiphytic microalgae as biological indicators for carbon monoxide concentrations in different areas of Peninsular Malaysia

Abstract

Microalgae are unicellular microorganisms with unique features and can be used as indicators for air pollutants. Microalgae have been found to withstand the negative effects of air pollutants. This study examined the relationship between the levels of carbon monoxide (CO) and the density of microalgal cells in different areas in Peninsular Malaysia, which has a hot and humid climate throughout the year. The influence of CO on the composition of microalgal species was also investigated. Microalgae samples were collected from four selected areas, chosen based on average CO readings for 2015 in the pattern of increasing values (low, medium, high) – Jerantut (low), Banting (medium), Kuala Lumpur (medium) and Petaling Jaya (high). The study found that Desmococcus olivaceus was the most widespread species found in the study areas whereas Trebouxia arboricola was the most dominant species. Trentepohlia rigidula, Coccomyxa confluens, Keratococcus bicaudatus, and Klebsormidium flaccidum can be categorised as non-tolerant to high levels of CO as they were only found in the area with low levels of CO, Jerantut. The study also showed that there was a perfect positive correlation between the CO levels and the number of microalgal cells. Data from the Jaccard Similarity Index indicates a low similarity in species composition between Jerantut and Banting, Kuala Lumpur and Petaling Jaya with Jaccard coefficients of 0.2857, 0.1250, and 0.1250, respectively. The outcomes from this study provide useful data in understanding the relationship of CO on microalgae cell density together with the composition of species and suggest the use of epiphytic microalgae as ecological indicators for air pollution.