Biodiversity is the variety of species in an ecosystem. In a biodiverse ecosystem, every niche is taken by many competing organisms. This is very important to all ecosystems, including the Peconic River. We are going to test invertebrate samples to record how biodiverse the Peconic River is, and we are focusing on macroinvertebrates. We have a wide variety of samples, such as what appear to be full grown beetles, leeches, dragonfly and damselfly nymphs. Using sequences of a section of the mitochondrial CO1 gene, we will attempt to identify the macroinvertebrates in the Peconic as either native or non-native species. We will also compare the results from this year to other years, to determine if the biodiversity has changed. Biodiversity studies and using DNA barcoding is important to understanding the state of the Peconic because greater biodiversity will result in greater stability in a river that has been plagued by poor water quality conditions for years.