Monitoring the variety and abundance of fish populations has never been easy, usually requiring unreliable visual assessments or tedious field sampling with nets. But marine scientists say they have found a much easier way. In fact, they identified 13,000 fish from a glass of water.
With just a small amount of water from a 1.2 million-gallon open sea tank at California's Monterey Bay Aquarium, researchers were able to sequence the various DNA it contained to arrive at an accurate picture of what species were living in the whole.
Lead researcher Ryan Kelly likens the water in marine habitats to a "soup of its resident species' genetic material, cast off in the forms of metabolic waste, shed skin cells, or damaged tissue." And now, thanks to advances in sequencing technology, scientists can easily compare the genetic material found in this soup to samples collected from organisms in earlier studies -- short bits of DNA called 'primers' -- to know which animals they belong to.
"Every one of those cells has DNA and if you have the right tools you can tell what species the cell came from," Kelly says.
For scientists performing marine life censuses, the ability to know what's there without having to encounter it directly could solve major challenges -- like in determining when fish stocks are depleted, or if an invasive species may have arrived to a particular area.