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Hozoji pond is a natural habitat of the almost extinct aquatic carnivorous plant, Aldrovanda vesiculosa L., where aquatic fauna has been investigated using fishing implements since 2010. Recent our field surveys using the fishing implements have shown small-sized fish species exist in the pond in addition to a large number of shrimps, tadpoles, and crayfishes; signs of large fish have been just witnessed there. Here we attempted the identification of aquatic vertebrates using environmental DNA (eDNA) and compared the results to those of field surveys in Hozoji pond and the surrounding, Mitagaya pond. We performed eDNA experiments using newly designed primers, cloning an eDNA fragment, and digesting with restriction enzymes. The results showed 49% of 70 clones were positively identified as vertebrates. Besides, gibels Carassinus sp. and snakehead Channa argus were detected, which have not captured these days. The species of 8 individuals of Carassinus sp. identified from mitochondrial DNA sequencing were distinct from those on morphological traits, suggesting crossing occurs in the pond. The methods of eDNA analysis in this study are competent to reveal a closed aquatic fauna, like Hozoji pond. The detailed fauna could be understood using eDNA as the complement to field surveys. |
