Isabel S. Castro-Rivera¹, Ana I. Ortiz-Colón^2,3, Nilsa M. Rivera-Cheverez², María A. Sosa-Lloréns²

¹ Department of Environmental Sciences, Rio Piedras Campus, University of Puerto Rico

² Department of Anatomy & Neurobiology, School of Medicine, Medical Sciences Campus, University of Puerto Rico

³ Department of Anatomy, School of Medicine, Universidad Central del Caribe

INTRODUCTION: Anthropogenic activities propitiate accumulation of toxic compounds within freshwater habitats. Crustaceans are a major part of aquatic ecosystems, yet little is known about the sensitivity of their nervous systems to water pollutants. Previous studies concerning the effects of river pollutants on freshwater fauna have focused on the animal’s survival response and their capacity to reproduce, and usually in response to high doses or long periods of exposure.  However, studies focused on the sub-lethal effects of river pollutants on the animal´s behavior and the integrity of the underlying neural circuitry are lacking. Phthalates and heavy metals have been demonstrated to act as neural disruptors.

METHODS: Thus, in this study, we looked at behavioral changes following short-term exposure to low (but above EPA standards) concentrations of dibutyl phthalate (DBP) 0.006 ppm and manganese (Mn²⁺) 0.207 ppm in the freshwater prawn Macrobrachium rosenbergii. Parameters of locomotion activity, such as total distance traveled, time spent moving at various speeds, and the pattern of locomotion within a fixed area were assessed.

RESULTS: We hypothesized that DBP would increase locomotion activity, because previous observations in our lab have shown that this phthalate can increase aggression, and that heavy metals such as Mn²⁺ would decrease activity. Injection of DBP initially reduced distance traveled, but the effect changed as time progressed, increasing distance travelled 24 hours after the injection. In the case of Mn²⁺, distance travelled did not change initially, but also increased 24 hours after injection. Both contaminants also induced the animals to spend more time away from the walls of their tanks, in comparison to control conditions where they received saline injections.

CONCLUSION: These results suggest that anthropogenic contaminants found in water bodies can affect behavior by increasing total distance traveled and disrupting patterns of locomotion in manners that can have an impact on the animal’s survival.

ACKNLOWLEDGMENTS: This work was supported by: NSF HRD-1736019 Puerto Rico Center for Environmental Neuroscience (Cycle II). To everyone who contributed to this project and showed their support for our work. Especially, Dra. Maria Sosa, Dr. Jonathan Crooke, Dra, Laura Vicente, Marcel Gonzalez, and Nilsa Rivera. My family for giving me the space to grow as a scientist.