Metabarcoding eDNA from Diverse Aquarium Fishes

In order to test the versatility of the newly designed primers for metabarcoding eDNA from fishes, we sampled seawater from four tanks in the Okinawa Churaumi Aquarium, Okinawa, Japan (26°41′39′′ N, 127°52′41^′′ E; figure 1). The aquarium was chosen because of the remarkable taxonomic diversity of fishes contained in a variety of tanks that resemble surrounding environments in the subtropical western North Pacific. The four selected tanks; Kuroshio (water volume =7500 m³), tropical fish (700 m³), deep-sea (230 m³) and mangrove (35.6 m³) tanks (figure 1a–d) harbour diverse groups of fishes (ca 250 species) from elasmobranchs (sharks and rays) to higher teleosts that vary greatly in their ecology, including both pelagic and benthic species living in shallow coastal to deep waters. In addition to these four aquarium tanks, we also sampled seawaters from coral reefs nearby the aquarium (26°42′35^′′ N, 127°52′48^′′ E; figure 1e,f) to preliminarily examine the use of the primers for metabarcoding eDNA from natural environments with unknown fish composition and abundances in an open ecosystem.
Figure 1.

(a–d) Four tanks used for water sampling in the Okinawa Churaumi Aquarium and (e,f) a sampling site in the coral reefs near the aquarium: (a) Kuroshio (water volume =7500 m³); (b) tropical fish (700 m³); (c) deep-sea (230 m³); and (d) mangrove (35.6 m³) tanks; (e,f) sampling site in Bise (arrow; 26°42′35^′′ N, 127°52′48^′′ E) and the Okinawa Churaumi Aquarium (star; 26°41′39^′′ N, 127°52′41^′′ E).