In Elkhorn Slough, an inlet on the California coast, seagrass grows healthy and strong in the shallow water. This healthy seagrass baffled marine biologist Brent Hughes. The scientist expected this estuary to be overrun with algae, causing the seagrass to die. Why was the seagrass thriving? As Brent investigated, signs pointed to an unexpected player helping to keep the seagrass healthy: sea otters! What do these top predators have to do with an aquatic grass at the opposite end of the food chain? Brent's discovery gave scientists insight into the delicate balance of ecosystems. Follow science in action as Brent conducts the research that led to this major discovery.