15:30 〜 17:00
[AOS13-P02] Analysis of the relationship between fish community composition and environmental factors in the Sea of Japan using environmental DNA
キーワード：環境DNA、小型浮魚類、魚類群集組成
Chub mackerel (Scomber japonicus), blue mackerel (Scomber australasicus), Japanese anchovy (Engraulis japonicus), Japanese sardine (Sardinops melanostictus), Japanese jack mackerel (Trachurus japonicus) and Pacific saury (Cololabis saira) are small pelagic fishes which show decadal species alternation. They are important not only as fisheries targets but also as intermediate trophic level which connects lower trophic and higher trophic levels. Their distributional dependence on environments have been studied for long periods. But studies on their species composition have been limited despite their species alternation is one of the significant phenomena in the ocean. Therefore, it is necessary to analyze the community composition of the small pelagic fish and its relationship with the marine environments to further understand the mechanism of the fish species alternation of small pelagic fishes.
Environmental DNA (eDNA), fish-derived DNA that is suspended or present in seawater, has recently started to be used to estimate fish habitat conditions (presence/absence, eDNA abundance, etc.). A multiplex real-time PCR method was developed for above 6 species. Then, we used the multiplex real-time PCR method to investigate the relationship between fish community characteristics and environmental factors in the Sea of Japan in this study.
Water sampling and hydrographic survey were conducted during August 23 - September 3, 2020 from the Tsushima Island to the Noto Peninsula in the Sea of Japan. Water samples were collected at depths of 10 m, 50 m, and 100 m (or just above the seafloor) using Niskin bottles. The collected samples were immediately filtered and cryopreserved during the voyage. The cryopreserved samples were subjected to multiplex real-time PCR using species-specific primers in the laboratory after the cruise. The resulting species-specific DNA concentrations were analyzed by distance-based redundancy analysis (db-RDA) to determine the relationship between fish community composition and environmental factors (water temperature, dissolved oxygen, turbidity, salinity, total depth, chlorophyll-a).
While no eDNA of Pacific saury was detected at any of the stations, the concentration of eDNA of Japanese anchovy was significantly higher than that of the other four species (t-test, p<0.01). Several offshore stations showed dominant composition of Japanese anchovy, whereas the eDNA concentrations of Japanese jack mackerel and chub mackerel were higher at several coastal stations. Furthermore, the results of db-RDA for environmental factors showed significant effects of salinity, total depth and water temperature on the species composition (Monte-Carlo permutation test, p<0.05). The first axis (db-RDA1) showed a positive correlation with salinity and a negative correlation with water temperature, while the second axis (db-RDA2) showed a high negative correlation with the total depth. The distribution of Japanese jack mackerel tended to be low in the area where Japanese sardine was abundant.
Environmental DNA (eDNA), fish-derived DNA that is suspended or present in seawater, has recently started to be used to estimate fish habitat conditions (presence/absence, eDNA abundance, etc.). A multiplex real-time PCR method was developed for above 6 species. Then, we used the multiplex real-time PCR method to investigate the relationship between fish community characteristics and environmental factors in the Sea of Japan in this study.
Water sampling and hydrographic survey were conducted during August 23 - September 3, 2020 from the Tsushima Island to the Noto Peninsula in the Sea of Japan. Water samples were collected at depths of 10 m, 50 m, and 100 m (or just above the seafloor) using Niskin bottles. The collected samples were immediately filtered and cryopreserved during the voyage. The cryopreserved samples were subjected to multiplex real-time PCR using species-specific primers in the laboratory after the cruise. The resulting species-specific DNA concentrations were analyzed by distance-based redundancy analysis (db-RDA) to determine the relationship between fish community composition and environmental factors (water temperature, dissolved oxygen, turbidity, salinity, total depth, chlorophyll-a).
While no eDNA of Pacific saury was detected at any of the stations, the concentration of eDNA of Japanese anchovy was significantly higher than that of the other four species (t-test, p<0.01). Several offshore stations showed dominant composition of Japanese anchovy, whereas the eDNA concentrations of Japanese jack mackerel and chub mackerel were higher at several coastal stations. Furthermore, the results of db-RDA for environmental factors showed significant effects of salinity, total depth and water temperature on the species composition (Monte-Carlo permutation test, p<0.05). The first axis (db-RDA1) showed a positive correlation with salinity and a negative correlation with water temperature, while the second axis (db-RDA2) showed a high negative correlation with the total depth. The distribution of Japanese jack mackerel tended to be low in the area where Japanese sardine was abundant.