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Life Science Research and Sustainable Development ISBN: 978-98-84663-33-9

ascertained to be 9, 6, 4 and 3 mg/100 g soil respectively of mercuric chloride. 59, 35, 18 and 10
mg / 100 g of soil respectively of copper sulphate and 140, 70, 35 and 17 mg per 100 g of soil
respectively of zinc sulphate. The graphically ascertained lethal dose (LD50) values with the help
of regression analysis for 24, 48, 72 and 96 h were found to be 9.509, 6.13, 4.798 and 3.017-mg/100
g soil for mercuric chloride, 59.533, 35.343, 18, 0904 and 10.339 mg/100g of soil for copper
sulphate and 140.012, 70.3217, 35.0017 and 17.8053-mg/100 g of soil for zinc sulphate.
Discussion:
Exposure to pollutants, even in exceedingly low concentrations, can elicit behavioural
responses in earthworms. Furthermore, because of their visibility, morphological abnormalities
can readily serve as definitive evidence of adverse effects. The term metal toxicity or metal
poisoning refers to the toxic effects of certain heavy metals in certain forms and doses on living
organisms. Thus, ranges of toxicity test have been proposed to assess the potential hazards of
pollutants to earthworms. In the present study as per OECD (1981), statistically calculated values
for the lethal concentration causing 50% mortality (LC50) of earthworm Perionyx excavatus by
mercuric chloride were found to be 9mg, 4mg, 3mg and 2 mg/100gm of soil for 24, 48, 72 and 96
h. For copper sulphate LC50 values were found to be 67mg, 36mg, 18mg and 10 mg / 100 gm of
soil for 24, 48, 72 and 96 h. LC50 values of zinc sulphate were computed as 166mg, 87mg, 49mg
and 23 mg /100 gm of soil for 24, 48, 72 and 96 h.
The present study revealed that survival of worms Perionyx excavatus declined with an
increase in the proportion of concentration added and with exposure time. Heavy metals impose
negative impact on growth of earthworms. Earthworms are the potential bio-indicators of heavy
metal contamination. Earthworms can act as bio-indicators for heavy metal pollution as the
survivability of earthworms indicated declining trends with the increased concentrations of
heavy metals Parihar et al., (2019). However, by minimizing the heavy metal contamination in
soil the earthworm population density may be enhanced. The toxicity values indicate that
mercuric chloride is more toxic than copper sulphate and zinc sulphate.
The study were investigating the impact of heavy metals (mercuric chloride, copper
sulphate, and zinc sulphate) on the survivability of earthworms, the significance of the findings
would likely relate to understanding the toxicity of heavy metals and how they affect the
physiology and survival of earthworms. One of the main significance of this research would be
to understand the mechanism of heavy metal toxicity and how it affects the survival rate of
earthworms. Earthworms play a crucial role in soil ecology and are considered bioindicator
species, meaning changes in their survival rate can indicate changes in the overall health of the
soil. Therefore, understanding the effects of heavy metal contamination on the survival rate of
earthworms can provide insights into the impact of heavy metal pollution on soil health.
Additionally, the study may find that heavy metal exposure leads to changes in the
survival rate of earthworms, and this information can be used as a guide for developing strategies
for mitigating the effects of heavy metal pollution on soil ecosystems. It may also give an insight
into which heavy metals are more toxic to the earthworm species used in the study. The study
may also find that different heavy metals have different effects on the earthworm survival, which
can help to understand which heavy metals are more toxic and which have a lesser effect on the
earthworm survival. Finally, earthworm survival rate is a well-known indicator of the overall soil
health, so if the study found that earthworm survival rate changes with heavy metal exposure, it
may be possible to use it as a bio indicator of heavy metal pollution in soil.
Behavioural responses and morphological symptoms have been recorded so far are as
follows: failure to burrow, curling of the body, violent coiling, slow and swift movement,

https://jesjalna.org/Zoology-Publications/index.html 126 Department of Zoology, J. E. S. College, Jalna