Nanotechnology, the ability to manipulate matter at the atomic scale, is being hailed as the next industrial revolution. While engineered nanomaterials (ENMs) possess incredible electronic, thermal, catalytic, optical, and mechanical properties, making them useful in a wide variety of processes and products, their potential ecological consequences have yet to be understood. Adding to this problem are the wide variety of ENMs being created and the inability of current toxicological methods to evaluate them all before they become problematic. For my work, I chose to examine the toxicity of three ENMs, ZnO, CuO, and carbon nanotubes, which are considered to be the most toxic based on previous studies, by evaluating their impact on a marine mussel, an organism that is central to marine coastal ecosystems. I use standard toxicological methods, along with physiological and demographic measurements, as well as fate and transport studies, and regression modeling to understand 1) the impact of ENMs on individual mussels, 2) the ability of mussels to influence ENM transport in marine environments, 3) the potential impact on mussel bed communities, and 4) the potential for trophic transfer of ENMs. I found that these ENMs are toxic to marine mussels but require levels probably not yet found in the natural environment. However, mussels are able to influence the fate and transport of ENMs by concentrating and depositing them in mussel beds, creating extremely toxic levels that will undoubtedly impact infaunal communities. Additionally, mussels accumulate all three ENMs during exposure, creating a potential route of exposure to mussel predators. While current regulations do not consider particle size when evaluating the safety of chemical substances and group most ENMs with their larger counterparts, my work, as well as that of other researchers, suggests that ENMs behave differently and need to be classified separate from larger forms.