Toxicity of Organophosphate and Pyrethroids Pesticides On The Tropical Freshwater Shrimp Xiphocaris Elongata

Abstract

Freshwater environments are highly dynamics but are subject to natural and anthropogenic influences. Although lotic ecosystems have resilience to deal with natural disturbance, the additional pressure from anthropogenic stresses can often lead to irreversible changes. Particularly, urban activities have resulted in increased anthropogenic discharge into freshwater environments with significant effects on organisms. The main objective of this thesis was to evaluate the toxicity of the freshwater shrimp Xiphocaris elongata to synthetic pyrethroid and organophosphate pesticides. Experiments were conducted in order to determine the effects of permethrin, malathion and glyphosate on different endpoints. Urban activities are known to decrease the abundance of organisms living in freshwater environments. For this reason, we evaluated the population status of X. elongata between urban and forest streams. The results showed that urban areas negative impact the abundance of the freshwater shrimp. These findings are consistent with symptoms associated with the urban stream syndrome. As part of urban activities, the uncontrolled application of organophosphate and pyrethroids pesticides like glyphosate, malathion, and permethrin has become a growing concern due to their ability to exert an adverse effect on non-targeted organisms. This research found that acute toxicity for permethrin, malathion and glyphosate progressively increases as the concentration of exposure pesticide increased. In natural environments, decaying leaf material may accumulate contaminants, including insecticides and herbicides. Thus, shredder shrimp can be exposed to these types of pesticide by leaf litter material. For this reason, we evaluated if the shredder shrimp display preference for feeding on different leaf species and leaf size area, while also assessing their consumption of leaves contaminated with pesticides. We also measured the acetylcholinesterase activity as a possible xii biomarker. The size area and plant species more appropriate for future toxicological studies is Spathodea campanulata leaves with a size area of 0.65 cm2 . This thesis showed that sublethal concentrations of malathion and permethrin in leaves have a significant effect on ingestion rates. Immunofluorescence shown a decline in acetylcholinesterase activity when sublethal dose of malathion and permethrin increases. This research highlights the potential of X. elongata as bioindicator to assess the risk of pesticide contamination in freshwater environments.

Citation

Torres-Pérez, Wesley X. 2020. Toxicity of Organophosphate and Pyrethroids Pesticides On The Tropical Freshwater Shrimp Xiphocaris Elongata. Master’s in science Thesis. University Of Puerto Rico, Río Piedras Campus. College of Natural Sciences, Department Of Environmental Sciences. Río Piedras, Puerto Rico 94 pp.