Impact of Heavy Metals on Survivability of Earthworms

Earthworms play a major role in enhancing the physical, chemical, and biological properties of soil. They are considered as keystone species within ecosystem and are used extensively as bioindicators of environmental contamination. Soil being the greatest heritage of mankind is the most valuable natural resource, has laid the foundation of agriculture since ages. The advances of humanity towards industrialization caused the production and entrance of hazardous pollutants such as carcinogenic compounds, toxins and heavy metals into the environment. Beneficial roles of earthworms on soil fertility, nutrient cycling and plant growth have been commonly observed. Earthworm activity improves soil physical conditions by burrowing and casting, with the formation of stabilized aggregates that allow easy penetration of water and air. Heavy metals are the main pollutants in the environment and are a big problem due to their toxicity and accumulation in the environment. Soils contaminated with heavy metals are one of the environmental issues considered to be a serious threat to human health and other organisms. This review provides information about the bioaccumulation of heavy metals on the earthworms and relating the mortality of earthworms with the concentration of heavy metals present in the soil.