This study explores how different oyster species contribute to water quality and biodiversity in urban estuarine environments like New York City’s East River. Oysters improve water quality through natural filtration and support biodiversity by creating reef structures that serve as habitats for marine organisms. By conducting field surveys and employing DNA barcoding, we will compare biodiversity in areas with native Eastern oysters (*Crassostrea virginica*) and non-native Pacific oysters (*Crassostrea gigas*). This research aims to uncover the ecological roles of these species, evaluate their impacts on water quality, and provide insights to guide restoration efforts and conservation policies for urban marine ecosystems.