Title : Acute toxicity of bleach exposure in macrobrachium crenulatum
Abstract:
Freshwater shrimp have become the most economically important and most internationally traded aquatic animal. Such high demand has led to unsustainable practices, such as the use of sodium hypochlorite also known as liquid bleach. Chlorine pollution has become a risk in the freshwater systems of Puerto Rico and many other countries such as the United Kingdom and India. In the island of Puerto Rico this has become a recurring risk since some fishermen are pouring liquid bleach in order to guarantee a bigger catch. Reports have become more common with the most recent one in July of this year. These practices disrupt water quality and kill many non-targeted organisms, leaving them to decompose in the river altering the water quality, ecological systems and the chemistry of riparian areas. To expose the severity of the issue and evaluate the ecological effect of such practices we exposed Macrobrachium crenulatum, a commonly fished shrimp species, to various concentrations of sodium hypochlorite (primary chemical compound in liquid blech), performing a lethal concentration fifty test (LC50). Fifty shrimp per round were selected (25 control and 25 experimental). To the 25 experiments we diluted a designated amount of sodium hypochlorite in the water and monitored and recorded every 24 hours for a total of 96 hours. We found that even at sublethal concentrations, the exposure caused significant changes in shrimp behavior. The bleach LC50 resulting value was approximately 6mg/L. These results provide the necessary information on the harmful effects of these practices, providing valuable information for conservation efforts and fishing regulations.
