Hyojin Ahn

Biodiversity is an important parameter for the evaluation of the extant environmental conditions. Here, we used environmental DNA (eDNA) metabarcoding to investigate fish biodiversity in five different estuaries in Japan. Water samples for eDNA were collected from river mouths and adjacent coastal areas of two estuaries with high degrees of development (the Tama and Miya Rivers) and three estuaries with relatively low degrees of development (the Aka, Takatsu, and Sendai Rivers). A total of 182 f

Abstract Environmental DNA (eDNA) is a convenient biodiversity monitoring tool, and many studies have focused on river and coastal areas, while deep‐water oceanic surveys are rare. However, using eDNA techniques to learn about oceanic communities may also be a useful approach. We tested methods to enhance ocean eDNA collections adding four different materials (sediment, diatomite, zirconia bead, and molecular sieve) in combination with 0.45‐μm pore size filter, also compared 0.22‐μm pore size fi

Environmental DNA (eDNA) surveys have been conducted to evaluate the distribution and abundance of Japanese eels. However, various environmental and biological factors may influence eDNA concentrations. An experiment was conducted using three water sample replicates (50, 100 and 200 ml) of the same group of eels in a tank that were exposed to sequential nonfeeding/feeding and low/high temperature conditions. Slightly higher concentrations occurred at higher temperature (22-23°C) with nonfeeding,

Abstract Biodiversity is an important parameter for the evaluation of the extant environmental conditions. Here, we used environmental DNA (eDNA) metabarcoding to investigate fish biodiversity in five different estuaries in Japan. Water samples for eDNA were collected from river mouths and adjacent coastal areas of two estuaries with high degrees of development (the Tama and Miya Rivers) and three estuaries with relatively low degrees of development (the Aka, Takatsu, and Sendai Rivers). A total

The diverse freshwater fish fauna of the Japanese archipelago is distributed among four main island landmasses, which include Hokkaido in the north, with many diadromous species. One relatively well-preserved river drainage along the southern coast of Central Hokkaido is the Mukawa River. Fish fauna surveys in the Mukawa River were mostly in downstream areas and the fish diversity is not well-documented among the upper, lower river, and coastal environments. Fish communities in the river, estuar

This study aims to examine the spatial variation of diatom abundance and composition along the nearshore areas of Biwase Bay and Hamanaka Bay, eastern Hokkaido. Terrestrial input <i>via</i> Kiritappu Wetland is expected to affect variation and composition differently depending on the position of the two bays. We conducted an oceanographic survey in June 2014 to measure seawater temperature, salinity, colored dissolved organic matter (CDOM) absorption, nutrient concentrations, and total and size-