For hundreds of years, coastal and marine ecosystems have experienced increasing threats due to the cumulative effects of increasing population growth and dependence on these ecosystems. Thus, there has been increased enthusiasm to mitigate the negative effects of human actions through the use of cleaner sources of energy, like marine renewable energy (MRE). The U.S. West Coast shows potential for tidal, wave, and offshore wind energy. Concern about MRE deployments has motivated research on the environmental effects of these new man-made hard structures in the ocean. Although this kind of development is relatively new in the U.S, placing man-made hard structure in coastal and marine ecosystems around the world has shown to create new habitat for algae, invertebrates, and fish and create foraging opportunities for birds and mammals, eventually becoming an artificial reef. The overall goal of my research was to use existing artificial structures to investigate a few specific effects of MRE development in Oregon waters. My research had two components: to assess the extent to which soft-sediment habitats are influenced by the presence of artificial structures deployed in Yaquina Bay, OR, and to characterize the biofouling communities present on bottom and surface artificial structures deployed offshore. Previous research indicates artificial structures modify sediment composition by increasing the erosion around a structure and that there is a close link between infaunal communities and sediment composition. Grain size analyses confirmed artificial structures change the physical environment around them, although these differences were not sufficient to cause a visible change in infaunal communities. Sediment characteristics also did not explain the greater infaunal abundances, mainly of Capitellidae polychaetes, closer to the structures than further away. Results indicated there were significant differences in sediment characteristics between locations in Yaquina Bay, most likely because of the greater amount of fine sediment at the sites located further upstream than those located closer to the mouth of the estuary. These differences in sediment characteristics appeared to be large enough to see a grouping of infaunal communities with location in Yaquina Bay. This study provided additional evidence that artificial structures alter their physical environment, but these structures and physical effects did not change the composition of the infaunal communities after a period of eight years. Assessing the biofouling cover on the offshore bottom and surface artificial structures showed that after a period of two years, the biofouling communities on the offshore bottom structures mostly consisted of balanoid barnacles, which resulted in little biomass. The bottom structures appeared to have been tipped over during their time in the water, potentially preventing the biofouling communities from developing more. In contrast, the surface artificial structures had greater overall cover, although cover mostly consisted of algae and gooseneck barnacles. Mussels, amphipods, crabs, and bivalves were found within the algae demonstrating the additional structure provided by the algae supported a greater variety of organisms on the surface structure. This study provided a “snapshot” of possible biofouling communities on offshore artificial structures, but longitudinal studies would enable us to monitor the development of the biofouling communities on these structures to better understand the mechanisms that caused the observed biofouling communities. Conducting these studies in an estuarine environment where in-stream tidal energy could be developed and in an offshore environment where wave energy devices would be deployed supplies greater specific knowledge about the possible effects of MRE devices in Oregon waters and also demonstrates the importance of site-specific research.