Microbial abundance and nutrient concentration in riverine and coastal waters of North-East Langkawi.
Bong, Chui Wei, and Lee, Choon Weng, (2005) Microbial abundance and nutrient concentration in riverine and coastal waters of North-East Langkawi. Malaysian Journal of Science, 24 . pp. 29-35. ISSN 13943065
University of Malaya. Institute of Biological Sciences. Laboratory of Microbial Ecology
We measured both biotic and abiotic variables at 19 stations along the three river systems and also off the Langgun island in the North-East (NE) Langkawi region. Temperature ranged between 29.8–31.3ºC whereas salinity ranged between 22–32. pH was between 7.4 and 8.2 whereas redox potential ranged between –82 to –32. Dissolved oxygen (DO) concentration ranged between 120–280 µM. Both pH and DO concentration were lower upstream of the rivers. For inorganic nutrient concentrations; ammonium (NH4) ranged between 0.56–4.30 µM, nitrate (NO3) between 0.31–1.46 µM, nitrite (NO2) between 0.04–0.38 µM and silicate (SiO4) between 1.36–15.23 µM. Of the nitrogen species, NH4 was dominant, making up to 79% of total dissolved inorganic nitrogen (mean=57%). Total suspended solids (TSS) in the water samples were high, ranging between 270 to 330 mg L^–1 whereas particulate organic matter (POM) constituted a very small component of TSS (<5%, 3.6–14.4 mg L^–1). For biotic variables, chlorophyll a (Chl a) concentration that represented the photoautotrophs present in the water, with the range of 1.49–8.24 µg L^–1. Bacteria ranged between 1.5–5.3x10^6 cells mL^–1 whereas phototrophic picoplankton and protists ranged between 1.7–4.3x10^5 cells mL^–1 and 0.8–1.6x10^4 cells mL^–1, respectively. Marine bacteria cultured ranged from 4x10^2 to 1.2x10^5 cfu mL^–1. Although our limited sampling was inadequate to detect controlling factors for bacterial abundance, our study showed that bacteria could have caused the lower DO concentration in the rivers in NE Langkawi.
|Keywords:||Bacteria, picoplankton, inorganic nutrients, chlorophyll a|
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