PS 64-15 - The effects of a common herbicide (atrazine) on juvenile crayfish growth and development

Friday, August 11, 2017
Exhibit Hall, Oregon Convention Center
Nathan T. Chandler, Austin M. Minuto and Kyle Harris, Biology, Liberty University, Lynchburg, VA

The Appalachian Brook Crayfish (Cambarus bartonii) are common in first to third order streams in eastern North America and can be a useful organism to study water quality. Atrazine is one of the most commonly used herbicides in the United States and it is introduced to aquatic environments through runoff. Stream concentrations usually do not exceed 20 ppb with concentrations in rural areas occasionally exceeding 50 ppb in short bursts. As an endocrine disruptor, atrazine has been shown to cause feminization in amphibians and fish. This project explores the effects of various concentrations of atrazine (0.005-50 ppb) on the growth and development of male crayfish. Thirty-five juvenile male crayfish were collected from a second order stream, carapace length (CL) and blotted wet mass (BWM) were recorded, and individuals were placed within various atrazine treatments for five months. After exposure, crayfish were removed to assess for morphological changes (carapace length and blotted wet mass) and then sacrificed to look for histological differences in the seminiferous tubules. It was expected that the level at which morphological and histological changes are displayed will be lower than the accepted safe level (3ppb) for human consumption.


A GC-MS cartridge method was used to detect the varied concentrations (0.05 – 50 ppb) of atrazine within treatments during the five month trial. However, the treatment of 0.005 ppb was not detected with the GC-MS and was not included with the overall results. Control crayfish had a higher BWM change when compared with the atrazine treatment crayfish. A decrease in spermatozoa was expected as atrazine concentration increased. As atrazine concentration increased, a trend of tissue degradation was observed. Such a decrease would suggest that sperm production will decline with increased atrazine exposure. However, initial findings do not show a decline in overall spermatozoa, but there is an evident degradation in tubule structure with increased exposure. It is concluded that these preliminary findings indicate that atrazine may have a negative effect on the sperm production of crayfish. However, the effects on fully developed crayfish are still unknown and will be the object of further study. These data improve the current knowledge of the potential anthropogenic introduction of endocrine disruptors on aquatic organisms and can be applied to riparian land management efforts.