Evaluation of fish biodiversity in estuaries using environmental DNA metabarcoding

Aka, Miya, and Takatsu Rivers contributed with 64, 72, and 81 species, respectively (Fig 2A). Eleven species commonly observed in Japanese coastal areas (yellowfin goby Acanthogobius flavimanus, blackhead seabream Acanthopagrus schlegelii, common carp Cyprinus carpio, Japa- nese anchovy Engraulis japonicus, largescale blackfish Girella punctata, dotted gizzard shad Konosirus punctatus, Japanese sea bass Lateolabrax japonicus, flathead grey mullet Mugil cephalus, Parablennius yatabei, Platycephalus sp. 2, and Takifugu spp.) were reported in all five estuaries. Cobitis takatsuensis, red stingray Hemitrygon akajei, Japanese jack mackerel Trachurus japonicus (NT), common carp, Japanese seahorse Hippocampus mohnikei (VU), Japanese eel Anguilla japonica, and redspotted grouper Epinephelus akaara (EN) are endangered according Table 3. Summary of models with ΔAIC < 2† used to assess the effect of human impact on the number of fish species. Model Variable Weight df AIC ΔAIC (Intercept) TN Revetment 1 4.557��� -0.214��� 0.608 3 76.02 0 2 4.552��� -0.24 0.001 0.231 4 77.96 1.94 †Based on comparison of null and full models in general linear model results; β coefficients of predictor variables are shown. Abbreviations: AIC, Akaike’s information criterion; TN: total nitrogen ���p < 0.001 in a Ward test https://doi.org/10.1371/journal.pone.0231127.t003 Fig 2. Species richness. Number of species present in (a) all five rivers and at each station, (b) Aka River, (c) Tama

River, (d) Miya River, (e) Takatsu River, and (f) Sendai River. HT: river mouth at high tide; LT: river mouth at low tide; L1: left 500 m; L2: left 1 km; R1: right 500 m; R2: right 1 km; S: seawater species; B: brackish water species having a wide range of salinity tolerance including migrating fishes; F: freshwater species. https://doi.org/10.1371/journal.pone.0231127.g002 PLOS ONE Biodiversity of five estuaries PLOS ONE | https://doi.org/10.1371/journal.pone.0231127 October 6, 2020 7 / 15