Environmental DNA (eDNA) has successfully proven the presence of invasive crayfish in almost all the small streams around Lake Akan in Japan, suggesting that eDNA analysis is an efficient and highly sensitive method to assess the distribution of aquatic organisms.
Environmental DNA (eDNA) has successfully proven the presence of invasive crayfish in almost all the small streams around Lake Akan in Japan, suggesting that eDNA analysis is an efficient and highly sensitive method to assess the distribution of aquatic organisms.
Researchers from Hokkaido University have found that signal crayfish, Pacifastacus leniusculus, may have endangered the habitat of Japanese crayfish, Cambaroides japonicas, through a survey method utilizing eDNA . The results suggest that signal crayfish are more widely distributed than Japanese crayfish in the streams around Lake Akan.
Freshwater ecosystems face a multitude of threats to their habitats. More than a quarter of all endangered species are among freshwater animals, roughly around 4,600 species worldwide. Biological invasions are a major threat to biodiversity loss in many ecosystems, including freshwater. eDNA is a genetic material extracted directly from environmental samples such as soil, water, air or leftovers from organisms. Lately, eDNA analyses are becoming a practical and cost-effective method for surveying aquatic species and efforts are being made to improve eDNA analyses and clarify their limitations. In previous studies, the distributions of the signal crayfish and Japanese crayfish have only been assessed by capturing specimens by hand without applying eDNA methods.
Read more at Hokkaido University
Image: Non-native signal crayfish (left) were found upstream of a 69 cm-high road-crossing culvert (right). (Credit: Kousuke I. et al., Freshwater Science. July 24, 2019)
