This document summarizes a study on the toxicity of lead exposure on the freshwater crustacean Gammarus pulex. The study investigated the effects of varying concentrations of lead exposure over 24 and 96 hours on biomarkers like locomotion, acetylcholinesterase activity, alkaline phosphatase activity, and antioxidant activity in G. pulex. Results showed that 24 hours of lead exposure significantly reduced locomotion of G. pulex compared to controls, but lead did not significantly affect the other enzyme activities. Longer lead exposures of 96 hours showed little effect, possibly due to acclimation of G. pulex to the toxic environment. The study aims to better understand the toxicity of lead and effects of varying exposure

1. Mechanisms of Lead Toxicity in
Gammarus pulex
Tracy Offiong Solomon
N0600833
Department of Biomedical Sciences. School of Science and Technology.
Clifton Campus. Nottingham Trent University. NG11 8NS
Introduction
Anthropogenic activities continue to pollute the world we
live in causing detrimental effects to man, animals and
plants (Urien et al., 2015; Vellinger et al., 2013). Gammarus
pulex are aerobic, freshwater organisms that have been
extensively used for the ecotoxicological studies of trace
metals (Urien et al., 2015; Vellinger et al., 2013).
Gammarids are popular for scientific research because they
have a wide distribution, clear sexual dimorphism, high
abundance, ease of collection, nutrient cycle and sensitivity
to various toxicants or metals (Vellinger et al., 2013; Urien
et al., 2015).
Lead is a non-essential metal and a major pollutant to the
biota (World Health Organisation, 1995). Anthropogenic
activities causing lead exposure include some of the
following: domestic wastes, mining, x-ray shielding devices
and metal products (Urien et al., 2015).
Therefore, considering the improper disposition of heavy
metals and the elevation of toxic pollutions and the
contaminated environment, this research was carried out.
Results and Discussion Contd.
researched. Data provided in this study showed lead
toxicity decreasing with increase in concentration in most
of the experiments as opposed to the research done by
Elwahaishi (2012).
24 hours of lead exposure had a greater effect on the
organism. 96 hours showed little or no effect. This may be
due to the acclimatisation of the gammarids to their toxic
environment (Richetti et al., 2011).
Methods
The following methods were used to obtain the results of
the research project:
• Lead exposure and behavioural analysis
• Acetylcholinesterase activity
• Alkaline phosphatase activity
• Antioxidant activity
• Protein assay and statistical analysis
Aims
• To investigate the effect of lead on the behavioural
biomarkers (locomotion), acetylcholinesterase activity,
alkaline phosphatase activity and antioxidant activity.
• To assess the effect of lead on the synthesis of
antioxidants.
• To determine the lethal concentration (LC50) of the
toxicity of lead on G. pulex when exposed with the range
of 24 and 96 hours respectively.
Figure 1: Effect of 24h lead exposure on the average velocity of G. pulex. Compared to the control, lead caused a significant
reduction on the velocity of the gammarids. Another significant reduction was also noticed between two concentrations
(0.01mg L-1 and 10mg L-1). Asterisks (*) illustrates significant differences (one – way ANOVA and Tukey test at – *: P < 0.05, **: P
< 0.01, ***: P < 0.005 and ****: P < 0.0001, n = 10).
Results and Discussion
After 24 and 96 hours lead exposure, results showed no
significant effect of lead on any of the enzyme activities
apart from locomotor activity. Lead was able to slow down
the movement of most of the gammarids in the
experimental groups as compared to the control groups.
The toxicity of lead on G. pulex has not been greatly
Figure 2: Effect of 96h lead exposure on the AChE activity of G. pulex. From the result, lead was not able to inhibit AChE activity.
Asterisks (*) illustrates significant differences (one – way ANOVA and Tukey test at – *: P < 0.05, **: P < 0.01, ***: P < 0.005 and
****: P < 0.0001, n = 5).
Conclusion
The effect of lead toxicity in the tested biomarkers of G.
pulex had no effect excluding its mobility. Further tests
should include longer exposure as this showed more
effects in other studies. Higher concentrations of lead
should also be considered.
References
Elwahaishi S. S. (2012). The Effect of the Sheep Dip Pesticide Diazinon on Behavioural and Molecular Markers in the Freshwater Shrimp
Gammarus pulex. [Online]. Available at: http://irep.ntu.ac.uk/199/1/212499_Salem%20Elwahaishi%20Decmber%202012.pdf.
[Accessed 31 August 2016].
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Urien N., Uher E., Billoir E., Geffard O., Fechner L. C. and Lebrun J. D. (2015). A Biodynamic Model Predicting Waterborne Lead
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World Health Organisation (1995). Environmental Health Criteria 165: Inorganic Lead, International Programme on Chemical Safety.