Spatial Difference in the Marine Algal Community of Yeongil Bay Inner and Outer Areas on the East Coast of Korea

This study examined the seasonal and spatial changes in the marine algal community structure in the outer and inner areas of the intertidal zone of Yeongil Bay. A seasonal survey was conducted at 13 intertidal sites in Yeongil Bay between August 2021 and July 2022. Algal samples were collected using a destructive approach, and the marine algal community was analyzed based on species composition, biomass, and the important value (IV) index. To confirm the differences between the outer and inner areas, ANOSIM and SIMPER analyses were conducted based on the biomass and IV indices of the marine algal species. The marine algal communities in the outer and inner areas of Yeongil Bay differed because of the high contribution of <i>Ulva</i> spp., as determined using the IV index. Our findings suggest that there was an influx of nutrients into Yeongil Bay from the Hyeongsan River, which had remained in the inner area for an extended period because of the slow current. This allowed <i>Ulva</i> spp., an opportunistic species, to bloom quickly and dominate the marine algal communities in the inner area. These results indicate a difference in the structure of marine algal communities between the outer and inner areas owing to the proliferation of <i>Ulva</i> spp. Therefore, <i>Ulva</i> spp. can be used as a target species to monitor the marine environment of Yeongil Bay.