Bottling biodiversity across a marine coastline
This summer a new scientific network will be sampling bottles of seawater from San Diego to Juneau, Alaska in order to assess the distributions of nearshore fish across this large and important coastline. But 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, and scientists can use this information, called environmental DNA (eDNA), to track species quickly across space. The Pacific eDNA Coastal Observatory (PECO) is a network of scientists and partner governmental agencies in Canada and the US. This summer will be PECO’s second year of sampling, marking what organizers at the Hakai Institute and McGill University hope to be the beginning of a continued time-series over the next decade. |
What information will this give us? The PECO network will be able to survey the coast-wide geographic distributions of hundreds of nearshore fish, as well as gain information about how species co-occur with specific environments, potential consumers, competitors, and invasive species, all from bottles of water. With time they will be able to track how species’ ranges change - as expected with climate change. This has been notoriously difficult to do with traditional sampling methods. So far, the PECO network has focussed on sampling seagrass habitats – a key fish habitat in nearshore systems – which allows them to maximize comparability across sites. This means they’ll have a new view of which fish live in seagrass habitats from Southern California to Juneau, Alaska, and how these change over time.
How do they do it? After the water is collected into sterile bottles, it is passed through finger-sized filters, which hold the DNA. The DNA is then extracted from these filters, and target regions of the DNA that are known to identify fish are “amplified” - a process that both isolates and multiplies the genetic markers of interest. These are then sequenced and compared to a reference database, that allows them to translate the sequences to known fish species like a ‘Rosetta Stone’.
Networks like the Pacific eDNA Coastal Observatory could mark the start of a new frontier in tracking underwater biodiversity. Groups like these are forming around the world - if they network, coordinate, and share we might soon be tracking biodiversity like we do the weather. |