Forensic limnology: Diversity of diatom population in relation to environmental factors in Gujarat region, India

Abstract

In drowning cases, diatoms provide an insight into ante-mortem and post-mortem evidence as well as aid in determining the geographical location. Diatoms are unicellular aquatic organisms that represent a major taxonomic division of the phytoplankton. The diversity of these diatoms depends on the geographical and environmental conditions as well as on the physico-chemical properties of the habitat. Hence, studying the diversity of diatoms in different water bodies in the Gujarat region will generate a diatomological map of the water bodies, which would assist in forensic analysis. In the present study, 100 water samples were collected from various water bodies, viz. rivers, lakes, ponds, etc., across 33 districts of Gujarat state, divided into 5 geographical regions (Saurashtra, Kutch, North, Central, and South). Identification of the diatoms was carried out by trinocular microscopic techniques. Physico-chemical parameters like pH, temperature, total dissolved solids (TDS), and electrical conductivity (EC) were also analyzed. Heavy metal concentrations were determined using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The diversity analysis reveals that each body of water in a different region has its own characteristics of diatoms. The physico-chemical parameters affect the diversity of diatoms by increasing their growth, but higher loads of heavy metals may affect the diatoms by reducing their growth and biochemical compositions. In conclusion, the present study provides an insight into understanding the regional patterns of diatom diversity and formulates reference conditions in these and other water bodies of this region.