What allows some species to establish, spread, and dominate in new environments while others fail? Biological invasions are a major driver of ecological change, yet the physiological traits that underlie invasion success remain largely unknown. We investigate how invasive species cope with novel and fluctuating conditions, including changes in temperature, oxygen, salinity, and water chemistry, and identify traits related to environmental tolerance, metabolic flexibility, and rapid acclimation. In parallel, we operate the Invasive Species Testing Facilities at SIO-UCSD, where we analyze water samples from municipal and state agencies to monitor high-impact invaders such as the quagga mussel (Dreissena rostriformis bugensis) and the golden mussel (Limnoperna fortunei) across California water bodies and delivery infrastructure. By linking physiological mechanisms with real-world monitoring, this work enables early detection and supports efforts to limit spread.