Sea Surface Microlayer (SML) is a layer between 1 and 1000µm which is a unique environment. Due to the difficulty in sampling the region, the composition of the SML environment is poorly understood. In the present study, an innovative approach for sampling this region has been demonstrated and the same has been compared with already existing sampling techniques of SML. The sampling technique we followed was termed as “Modified Membrane Method” which proves to be an efficient sampling method by reducing the chances of contamination of microbes from adjacent layers. The isolated strains were subjected to biochemical and molecular sequencing studies. The biochemical tests showed most of the ...view middle of the document...
Although several studies have compared bacterial abundance (Agogue et al, 2005; Joux et al, 2006, Cunliffe et al, 2009) between bacterioneuston and bacterioplankton, knowledge of the composition of the bacterioneuston was lacking.
Microorganisms in the sea surface microlayer are subjected to a combination of favourable and detrimental factors. Favourable factors are high concentrations of organic and inorganic nutrients and detrimental factors are high concentrations of heavy metals and organic pollutants, solar radiation in the UV and visible spectra, salinity changes and temperature fluctuations. Therefore, the SML has often been considered as an extreme environment for microorganisms that may contain unusual species and taxa (Maki, 2002). In addition, different reports suggest that microbial concentration exceeds that of subsurface waters by orders of magnitude (MacIntyre, 1974 and Hardy, 1982), but despite their abundance and widespread distribution, bacterial communities thriving at the SML are poorly characterized (Norkrans, 1980). The present study is the first of its kind in examining the bacterial community of SML in the coastal waters of the Palk Bay region, South India.
Materials and Methods:
SML samples and the corresponding sub surface waters were collected at two different stations under calm wind conditions in the coastal waters of Palk Bay region, South India during October 2011. The sampling was taken at 6.00 and 06.30 GMT. The latitudes and longitude co-ordinates of two sampling stations viz., Station 1 and Station 2 were N 9º17’40.3"; E 79º09’15.2" and N 9º17’43.5" ; E 79º09’16.0" respectively (Figure. 1).
The SML was sampled using different techniques described elsewhere like Glass plate method (Agogue et al, 2004), Teflon plate method (Kjelleberg et al, 1979), Membrane method (Hu¨hnerfuss, 1981) and by our own fabricated device (Fig. 2) termed “Modified Membrane Method” (MMM) to determine the effective sampling technique for studying microbial community of SML. The membrane used in this study was Poly Etho Sulfonate (PES) membrane, hydrophilic with pore size-0.2µm (No. 66234, PALL life sciences). Sub surface water (SSW) was also collected by submerging a screw cap tube and opening and closing it at a depth of 0.5 m.
Modified Membrane Method:
The SML sampling was carried out by a fabricated device (Figure 2) which consists of wooden board of thickness 25 mm, glass plate, teflon plate, measuring scale and membrane holders. The wooden board measuring 28cm × 14cm size is carved with 26 mm hole in the centre. A glass plate (7.5 × 7.5cm) was fixed above this hole to have clear visibility while descending the device close to sea surface. At the bottom of the board a teflon plate was fixed with a provision of two pin holder at both ends for holding the membrane. Two small wooden pieces were fixed at both ends of the lower surface of the board to prevent any splash that moisture the sampling membrane and...