DNA+Science+n+CSI

https://newsela.com/articles/sharks-DNA/id/24341/ The seawater samples also contained DNA fragments from mackerel tuna, which spawn near Al Shaheen. In fact, the greater the concentration of whale shark DNA, the greater the concentration of tuna DNA. The reverse was also true. When whale shark DNA was relatively scarce, tuna DNA was scarce as well. The researchers said this is most probably a sign that the whale sharks had come to the area to hunt the tuna. Other groups have already used environmental DNA to identify the inhabitants of certain waters. However, the authors said that this study accomplished something new. It is the first to show that environmental DNA can provide meaningful information about a population of animals and the biodiversity of their habitat.