Marine macroalgal community structure of subtidal zones were examined at eight study sites, Jeju, Korea, from March to June 2010. A total of 182 species were identified, including 22 green, 37 brown and 123 red algae. Of them, 15 species were observed at all the study sites. Species richness of seaweeds was maximal at Seongsan with 112 species and minimal at Sinheung with 44 species. Average seaweed biomass was 735.24 g wet wt. m-2 and ranged from 165.82 g wet wt. m-2 at Sinheung to 1,160.43 g wet wt. m-2 at Bomok. Articulated coralline algae were dominant occupying 27.05% (198.92 g wet wt. m-2) of total biomass for the eight study sites in Jeju Island. Subdominant species were Ecklonia cava and Codium coactum, comprising 26.62% (195.72 g wet wt. m-2) and 8.42% (61.91 g wet wt. m-2), respectively. Vertical distribution of subtidal seaweeds in terms of biomass showed from E. cava Colpomenia sinuosa - Codium coactum Ecklonia kurome Undaria pinnatifida - Cladophora wrightiana - Peyssonnelia capensis in the subtital zone between 5~15 m depth level.

This study histologically describes the intersexuality of Scomberomorus niphonius collected from the coastal area near Jeju Island. A total of 126 S. niphonius, collected from March to July 2012 with a total length of 62.4 cm (±17.5) and a total weight of 1,701.9 g (±1,528.9) were used for analyses. From a histological perspective, two types of intersex were confirmed. One type had scattered germ cells from the opposite sex within the gonad. The second type developed germ cells from the opposite sex in the connective tissue of the outer gonadal membrane. The intersexuality was 14.3% (n=18/126), with females (21.3%; n=16/75) exhibiting a higher rate than males (3.9%; n=2/51). There was no displayed correlation between intersexuality and the total length and weight.