Seaweed Beds and Community Structure in the East and South Coast of Korea

Abstract

This study conducted a community investigation via scuba-diving excursions into the subtidal regions of seven sea areas on the eastern coasts and three sea areas on the southern coasts, from October to December 2017, to determine the characteristics of seaweed communities and the current status of barren ground in natural seaweed beds in Korea. The results showed that species composition and average biomass in the sea area were 5–48 species and an average of 114.42 g/m2 (0.29–273.60 g/m2) in the eastern coasts, where red algae—an annual opportunity species—were dominant, and 21–48 species and an average of 1056.84 g/m2 (53.03–2683.02 g/m2) in the southern coasts, where perennial large brown algae were dominant. Using Orfanidis’ EEI-c model, evaluations of the community states showed they varied significantly depending on the inclusion of melobesidean algae, and this model was determined to be inappropriate for direct application in sea areas with a low coverage of all macroalgae. A comprehensive review of the seaweed community characteristics of seaweed beds, the marine environment, the coverage of melobesidean algae, and the analysis results regarding the density of grazers showed that a decrease in the seaweed community, according to the barren ground phenomenon, was more severe in the eastern than southern coasts. Furthermore, there were also significant differences in seaweed community characteristics according to sea area and barren ground. Therefore, suitable countermeasures corresponding to the characteristics of each sea area are necessary; for example, the creation of growth substrates for the colonization of macroalgae in Deoksin and Saido Is., the transplantation of large brown algae in Gangyang and Daedurado Is., action plans for marine forest monitoring in Geomundo Is., and an improvement in substrates in Yeongjin, Mangsang, Daejin, Chogok, and Geundeok are possible countermeasures.

Temperature-Dependent Food Consumption Rates of the Sea Urchin Mesocentrotus nudus and Top Shell Turbo sazae: Potential Impacts on Seaweed Beds

“…The sea urchin M. nudus is one of the most abundant macrograzer species along the eastern coast of Korea, with population densities of 1 to 12 ind −1 m −2 [76]. It is believed to significantly contribute to the formation of barren ground due to overlap between its distribution and areas where seaweed has been depleted [19,20].…”

Alterations in sea urchin (Mesocentrotus nudus) microbiota and their potential contributions to host according to barren severity

“…Restoration efforts have been conducted in several countries, but an effective solution to relieve the damage caused by the urchin barren has not been reported yet [14][15][16] . The area of the urchin barren on the eastern coast of South Korea has expanded from 2413 ha in 2003-2004 to 10,518 ha in 2014 17 . Sea urchins are a major factor in the expansion of barren owing to a significant correlation between macroalgal abundance and sea urchin density on the eastern coast of South Korea 18 .…”