A case study of the northernmost distribution limit shift of a soft coral Dendronephthya sp. in the East Sea of Korea

Abstract

The migration of diverse organisms both on land and under the waters is highly affected by climate change which has several effects on human life. While there are sufficient amounts of papers touching upon the subject of migration for species on land, there is a need for more studies on the migration of marine organisms. Especially in urgent need are observations of the coral migration in the East Sea of Korea, which is reported to have a fast sea temperature rise. The East Korean Warm Current (EKWC) has the potential to help the migration of diverse coral species to settle in the East Sea, which would bring unimaginable impacts. Whether these impacts would be positive or negative still needs to be assessed, and therefore, the objective of this paper was first to report scientific evidence of the settlement of the Dendronephthya sp. in the East Sea, Wangdol Reef, to be specific. This indicates that the northernmost distribution limit of the Dendronephthya sp. shifted up to the East Sea of roughly 200km. We hypothesize that the small ones would have settled in 2021 when the EKWC was the strongest and the sea temperatures were the highest compared to the past ten years. For the biggest colony found in the middle summit, we speculate that it has been around for at least more than two years, as the size was approximately 40cm. The reason why it has succeeded in settling only in the Wangdol Reef and whether it will stay around still remains as a question. Nevertheless, the observation itself provides a new platform for numerous amounts of new discoveries to be made in the rapidly growing field of coral ecology in Korea.