Study area

The wetlands of urban and rural districts of Bangalore, South India were surveyed for diatoms and water quality assessment during February – March 2009. This communication reports of samples from two wetlands.

1. Thalghattapura wetland (12° 59’ N - 77° 32’ E Altitude) is located at south part of Bangalore. The wetland is 2.5 m depth with a catchment of 217.5 ha including water body, open fields, forest and residential areas. This wetland also receives domestic sewage from nearby residential area.
2. Begur wetland (lat/long 12° 52′ 20″ N - 77° 37′ 58″ E Altitude) is situated in the southeast sector of Bangalore with an area of 49.8 ha and a depth of 3 m. Agricultural fields and residential area surrounds the immediate vicinity of this wetland. This wetland is considered sacred due to the presence of a 1300-year-old Dravidian temple from the Chola Dynasty. This wetland also receives domestic sewage from nearby residential area.

Sample collection and treatment

Epiphytic samples were collected from aquatic plants near the wetland inlet region by crushing the submerged roots and stems in polythene cover and resulting suspension transferred into a plastic storage container. Epilithic samples were collected by vigorously scrubbing 3–5 stones from the substratum with a toothbrush and resulting suspension transferred into plastic storage container. Further both samples were preserved in 70% ethanol.

A portion of sample was cleaned by removing the organic matter using hot HCl and KMnO₄ treatment (Taylor et al. 2007; Karthick et al. 2010). Subsamples of the cleaned material were mounted onto glass slides with Naphrax^® as the mounting medium and subsequently observed with an Olympus BX-51 light microscopes equipped with DIC optics and a Jenoptic digital camera for image capture. Scanning electron microscopy was done with cleaned specimens air dried on small squares of aluminium foil, and mounted on aluminium stubs using double-sided carbon tape. Stubs were sputter coated with gold and subsequently examined with a FEI XL30 ESEM (Ottawa) using accelerating voltages of 5–30 kV and a working distance between 7–12 mm. Alternately cleaned specimens were air dried onto cover glasses, attached to aluminium stubs, sputter-coated with 10 nm of Au-Pd, and examined in high vacuum mode with FEI Quanta 200 ESEM at the Nanoscience Initiative Facility, Indian Institute of Science. Water chemistry analyses were carried out according to the standard methods (APHA, 2005; Trivedy and Goel, 1986).

Abbreviations: LM=Light microscope; SEM=Scanning electron microscope. CESH = Centre for Ecological Science Herbarium Diatom Collection, Indian Institute of Science, Bangalore, India. Other herbarium abbreviations follow Index herbariorum (http://sweetgum.nybg.org/ih/).