Critical Study of the Diversity and Abundance of Nematodes in Pollution Prone Urban and Rural Areas of Thiruvananthapuram District in Kerala, South India

Nematodes represent a very abundant group of soil organisms in the food web and are important for
soil quality. In the present study, the diversity of nematodes in the soils of urban and rural areas of
Thiruvananthapuram District was noted and their densities calculated. Different categories of land use
areas (coastal area, sewage disposal area, industrial area, road-side area, agricultural area, gasoline
station area and market area) in rural and urban parts of Thiruvananthapuram District receiving
different types of contaminants were selected after conducting a reconnaissance survey. Control
stations which are in a benign environment were also identified in both rural and urban areas of
Thiruvananthapuram District in Kerala, South India. Soil samples were collected in pre-monsoon,
monsoon and post-monsoon seasons during the period April 2009 to January 2010 from the selected
stations. The soil nematodes were identified and their abundance calculated following standard
procedures. The results showed that the soils in the market area are having the highest nematode
abundance and diversity index. It was also noted that the nematodes were scarce in the soils of
gasoline station area contaminated with hazardous wastes and chemicals which will unfavorably
affect the nematode population. The nematode abundance in the soils of the study stations are in the
order: market area > sewage disposal area > agricultural area > benign environment > industrial area
> road-side area > gasoline station area > coastal area. The present study showed that the
nematodes can act as bioindicators of pollution as their numbers diminished in contaminated soils.