Japan's Ogasawara Islands are an isolated chain of small, volcanic islands a thousand kilometers south of Tokyo.
Tim Ravasi
A research team from the University of the Ryukyus (UR) and the Okinawa Institute of Science and Technology (OIST) have published a study based on environmental DNA sequencing or eDNA to obtain a more detailed understanding of the species that live in the Ogasawara Islands.
The researchers' process involves collecting environmental samples, including water, soil, and air and therefore discovering islands’ marine diversity, including fish and coral.
In more detail, the sample recollection revealed 38 unique genera of coral and 124 unique fish species including species living outside their known ranges.
Regarding the process, UR Professor James Reimer explained: "We wanted to investigate the diversity of very isolated oceanic islands and compare that with other areas such as mainland Japan or continental Australia. We collected seawater from nine sampling sites around Chichijima, one of the Ogasawara Islands, and extracted eDNA from these."
Additionally, Professor Timothy Ravasi of OIST indicated: "As well as a huge range of species, we also saw evidence of local coral bleaching, which is perhaps one of the biggest problems for the islands."
According to the Global Seafood Alliance, Japan’s Ogasawara Islands are vulnerable to external impacts such as climate change, and their location makes it difficult to regularly assess their ecological health.
Its value as a biodiversity hotspot with many unique species is so great that it has been dubbed the Galapagos of the East and designated a UNESCO Natural World Heritage site.
"Remote islands like the Ogasawaras are more susceptible to stress because there is less connectivity with other regions. Species are quite isolated genetically, which could make them more susceptible to environmental shifts like climate change," Ravasi clarified.
On the other hand, the report mentions the impact of human development on biodiversity. For this, the team also took seawater samples from three locations along Futami Bay, where the main settlement relies.
Because ports had an important diversity of fish several marine assemblages have also been altered due to extensive coastal development.
"These contrasting patterns of fish and coral assemblages could be due to species- and taxa-specific responses and vulnerabilities to environmental gradients, as well as their long-term resilience in the face of climate change and other anthropogenic impacts," said Professor Oshima Açıkbaş.
Now, the question is if eDNA technology can be applied in freshwater aquaculture systems as a way of monitoring pathogens and exploring diseases and parasite surveillance.
"As a non-invasive method, it’s a promising tool, particularly for disease diagnosis, while it also facilitates disease forecasting. We can forecast disease by quantifying the pathogen load based on the amount of eDNA," Kailash Bohara, extension specialist-I for aquaculture and diagnostics at the University of Arkansas at Pine Bluff assures.
Finally, Professor Martin Llewellyn of the University of Glasgow, who investigates the impact of planktonic communities on Scottish salmon farms, and his team are using eDNA to study farmed salmon environment and disease and mortality. causes.
"Salmon farmers want a low-cost, reproducible way of assessing the abundance of a particular species, and more targeted approaches like qPCR may deliver this in the future. There could be ways of taking an eDNA approach on farms, for example via dipstick tests in a pen or production facility. eDNA is potentially a very useful tool but there is still a discovery phase that needs to happen," Llewellyn noted.
