Seawater: memory keeper, energy source, and pollution tracking

Sampling seawater just below the surface of a seagrass bed in Quatsino Sound, British Columbia. Credit: Mike McDermid What can a bottle of seawater tell you about the fish living below?. Seawater holds -memories- in the form of DNA from fish and invertebrates that have recently passed by. This information, called environmental DNA or eDNA, can be used by scientists to track species across space. This new approach is being used by researchers like McGill Professor Jennifer Sunday and her colleagues at the Pacific eDNA Coastal Observatory (PECO) to track -biogeography- like we forecast the weather. The PECO network has been collecting seawater in bottles from Juneau, Alaska to San Diego, California to find out which fish live where and how these change over time, focusing on seagrass habitats across this large coastal region. With this information, the researchers will survey the geographic distributions of hundreds of fish and gain a better understanding of how species live together in different environments - as potential consumers, competitors, and invasive species - all from bottles of water.