Quagga mussels (Dreissena Bugensis), an invasive species to the Great Lakes, have become highly successful in the Great Lakes in part due to their reproductive vigor. During spawning season, males and females release gametes into the water column where external fertilization occurs, resulting in free-swimming, planktonic larvae. Females can produce more than one million eggs per season and males can release even more gametes. As filter feeders, quagga mussels uptake various compounds, including pharmaceuticals, which have become increasingly prevalent in surface waters. The 5-hydroxytryptamine (5-HT) serotonin receptor plays a key role in mussel physiology, influencing behaviors like spawning. This study investigates the effects of pharmaceuticals on quagga mussels, focusing on compounds that act as 5-HT receptor agonists and antagonists, such as sumatriptan (agonist) and trazodone (antagonist), both commonly prescribed to humans. Aspirin, which can disrupt neurotransmitter systems, was also examined. Preliminary findings suggest aspirin inhibits spawning, while sumatriptan and trazodone affect filtration rates. Understanding how these pharmaceuticals affect quagga mussels is vital for assessing the ecological consequences of pharmaceutical contamination in aquatic environments and could be crucial for managing the spread of this invasive species. This research will contribute to our understanding of how pharmaceutical pollutants can impact invasive species, particularly quagga mussels, in freshwater ecosystems. By focusing on the serotonin receptor and its role in mussel physiology, this study may reveal novel insights into the broader ecological effects of pharmaceutical contamination on freshwater organisms. Furthermore, it will provide valuable information for the development of management strategies aimed at controlling the spread of quagga mussels and mitigating their impact on aquatic ecosystems.