Diatomological Profile at Discrete Depths of Powai Lake, Mumbai for Medico-Legal Purposes

Diatoms are photosynthetic microorganisms that play important role in forensic diatomology in the diagnosis of drowning deaths. In the present study, the Diatomological profile of Powai lake was prepared for medico-legal purposes using the Shannon-Wiener index. Powai lake (19.1266° N, 72.9062° E) is a large artificial lake situated in a northern suburb of Mumbai. Diatoms sampling was conducted in February 2017 from this lake. This study aimed to identify the various genera of diatoms and to determine the relative abundance, generic counting, and diversity index of diatoms for the medico-legal purposes. Littoral benthic diatoms of five locations were sampled from this lake. Diatoms slides were prepared by scraping the rock surface with an area of 3x3 cm, diluting in 50 ml distilled water, and identification under the microscope with 1000 magnification. Identification of 17 genera of diatoms was done using the web-based visual guide ‘Diatoms of the United States’. Diatoms belong to both the orders Centrales and Pennales. The pH of the lake water was found to be 7.64 i.e. slightly alkaline and the temperature was 27°C. Water quality parameters showed a fairly good value for the growth of diatoms. Samples were dominated by class Bacillariophyceae, which included 9 genera followed by Coscinodiscophyceae, with 6 genera, and Fragilariophyceae, with 2 genera. Generic counts of diatoms were obtained by using the ‘Neubauer’ Counting chamber. The Shannon-Wiener diversity index (H') ranges from 1.042 in Epipelic to 0.454 in Emerged Epiphytic diatoms. The purpose of this study was to prepare a diatomological profile of diatoms at discrete depths for medico-legal purposes.