Jae Ho Lee’s scientific contributions

We aimed to analyze the natural population characteristics and habitat growth conditions of the valuable seaweed Silvetia siliquosa. Its population characteristics and habitat conditions were assessed monthly from May 2022 to April 2023 and April to August 2022, respectively, on selected habitats. The average population density, coverage, and frequency of S. siliquosa were 579 ± 94.18 ind./m2, 27.82 ± 6.92%/m2, and 78.37 ± 5.98/m2, respectively. The average thallus length and width were 47.53 ± 4.35 and 46.33 ± 4.17 mm, respectively, while the branch width, thickness, and frequency were 2.35 ± 0.03 mm, 0.59 ± 0.12 mm, and 2.8 ± 0.2 times, with a receptacle length and width of 24.13 ± 2.07 and 2.81 ± 0.19 mm, respectively. Among the 40 previously known natural habitats of S. siliquosa, growth was confirmed only in Sepo, Sebang, and Bangpo. The causes for the declining S. siliquosa populations could be attributed to habitat changes due to construction, coastal road maintenance projects, habitat disturbances, and increased pollutants. Habitat substrate disturbances and changes were the main causes of the decrease in S. siliquosa growth. Studies on environmental factors and habitat degradation, growth related to environmental factors, mass cultivation, and the marine ecosystem restoration of S. siliquosa are needed.

This study was conducted in June and September 2022 to analyze the macrofauna community of Dokdo. The total number of macrofauna in Dokdo is 120 species (annelida 10, arthropoda 30, chordata 1, cnidaria 3, echinodermata 7, mollusca 60, nemertea 1, porifera 7, sipuncula 1), and the average biomass was 3,624.65 g/㎡ in total (annelida 1.20 g/㎡, arthropoda 381.16 g/㎡, chordata 0.38 g/㎡, cnidaria 0.78 g/㎡, echinodermata 32.74 g/㎡, mollusca 3,182.89 g/㎡, nemertea 0.28 g/㎡, porifera 23.75 g/㎡, sipuncula 1.46 g/㎡), and the everage individuals was 376.67 ind./㎡ (annelida 28.89 ind./㎡, arthropoda 224.56 ind./㎡, chordata 0.11 ind./㎡, cnidaria 1.33 ind./㎡, echinodermata 4.44 ind./㎡, mollusca 103.33 ind./㎡, nemertea 0.22 ind./㎡, porifera 1.78 ind./㎡, sipuncula 12.00 ind./㎡). 60 species, 238.37 g/㎡, 135.33 ind./㎡ from haenyobawi, 83 species, 10,038.61 g/㎡, 776.35 ind./㎡ from ddongyeo, 78 species, 596.96 g/㎡, 218.33 ind./㎡ from hogdomgul were investigated. The number of species, average biomass and average individual showed the highest values in ddongyeo. The dominant species of marine macrofauna based on biomass were Mytilus unguiculatus at 2,778.45 g/㎡, Pseudoctomeris sulcata at 279.19 g/㎡, Turbo cornutus at 132.11 g/㎡, Neopycnodonte cochlear at 199.26 g/㎡ and Ostrea circumpicta at 80.86 g/㎡. In both the survey period, Mytilus unguiculatus were the highest at 2,466.19 g/㎡ and 3,090.70 g/㎡, respectively, and it was judged to be a good environment for mussels to inhabit. Research on marine macrofauna in Dokdo has been conducted irregularly in the past, and continuous research and long-term monitoring are needed to accurately determine the community structure.

This survey was conducted to investigate the species, area, water depth and density of seagrass to the south east coast using field survey (SCUBA diving) and drone aerial photography. The occurrence seagrass in this survey were 6 station of Geoje (Yegu, Gujora, Dadae, Dapo, Geunpo, and Daepo) and 5 station of Tongyeong (Chuwon, Bongam, Changgwa, Yeomho, and Chukpo), and Zostera marina, Zostera caespitosa, and Halophila nipponica were investigated. Habitat area was the largest at 20,788 m2 in the Dadae and the smallest area was 51 m2 in the Chukop. Density was highest at 182.4 shoots/m2 in Geunpo and lowest at 89.6 shoots/m2 in Yeomho. Most of the water depths were around 3 m, but in Bongam, it was found that even at 7 m depth, the form of the Zostera marina was grassland and the Zostera caespitosa was distributed in the form of a patch. Compared with the previous studies, the area was increased or decreased depending on the survey region, but the occurrence species did not find Zostera caulescens, Zostera japonica, Phyllospadix iwatensis.