Prof. Masahiro Nakaoka1, Dr. Kenji Sudo2, Dr. Hiromori Shimabukuro2, Dr. Masakazu Hori3
1Hokkaido University, Akkeshi, Japan, 2Japan Fisheries Research and Education Agency, Hatsukaichi, Japan, 3Japan Fisheries Research and Education Agency, Yokohama, Japan
Broad-scale data on the distribution of seaweed and seagrass beds are still insufficient in Asian countries. In Japan, the Ministry of the Environment recently released the results of a nationwide survey on the distribution of seaweed/seagrass beds conducted from 2018 to 2020. The total area of seaweed/seagrass beds was estimated to be 1,640 km² (excluding some semi-closed seas), which was 60% of that in 1989-1991 when the previous survey was conducted. While many reports showed the decline in area during this period, some reported the increase in area with water quality improvement and successful restoration projects. In this study, we conducted a broad-scale analysis on the long-term changes in seaweed/seagrass beds and compared the results among different regions of Japan and between bed type (seaweed and seagrass beds). Preliminary analysis on temperate seaweed beds showed that the rate of increase or decrease varied greatly, ranging from 0% (total disappearance) to 8600%, although no consistent trend in the pattern of seaweed bed change was detected. In the 2018-2020 report, many new algal beds were added that were not reported in 1989-1991, which may led to an overestimation of the increasing rate. Further validation based on other source of data is needed to precisely evaluate changes in seaweed/seagrass beds over broad-spatial scales.
Biography:
Masahiro (Massa) Nakaoka is a professor of Hokkaido University and the director of Akkeshi Marine Station, Field Science Center for Northern Biosphere, Hokkaido University where he has been working for since 2008. His research interests lie in the area of marine ecology, ranging from basic subjects like plant-animal interactions, to more applied ones like evaluation of multiple ecosystem services from coastal ecosystems in Asia. He has collaborating activities with researchers in other countries, using Akkeshi Marine Station as a node of international network studies.
