The autecology of the Zostera marina and Z. japonica was studied in populations growing in the same locality (Sagumi Bay, southwestern coast of Korea). Environmental factors and plant characteristics were examined monthly from August 2008 to September 2011. Along intertidal zone, Z. japonica (0.1-0.5 m above mean lower low water, MLLW) occurred above Z. marina (0.5-2.5 m MLLW). Tidal exposure at low tide during day was the highest in the spring and the lowest in the summer. Underwater Irradiance showed seasonal fluctuation that was the highest in spring and summer caused by tidal pattern. Strong seasonal patterns in water temperature appeared to control the seasonal variations in morphology, biomass and leaf growth. The seasonal pattern of Z. japonica resembled that of the Z. marina in morphological characteristics, above-and below-ground biomass, whereas it differed in shoot density and leaf elongation. Despite some similarities in seasonal growth patterns, the patterns of Z. japonica were lagged by 2 month of Z. marina. Seasonal variation in the above biomass of Z. marina was caused by changes in density and plant size, whereas that of Z. japonica was mainly caused by changes in shoot density. Zostera marina was more sensitive to high temperatures than Z. japonica, and the increasing water temperature during the summer became the factor that inhibits the growth of the Z. marina.
Zostera Japonica, there is no clear change according to the amount of the light. It is because its habitat locates above that of Zostera marina so that the amount of the light that is necessary to growth is enough and in this condition, any preventing factor does not seem to work at all. Although underwater light getting into Zostera marina's habitat is very low level and there is no any hindrance to the survival of them, it prevents them from their productivity a bit.

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 연구지역
  2.2. 환경요인 분석
  2.3. 해초 분석
  2.4. 통계 분석
 3. 결 과
  3.1. 환경요인
  3.2. 생육밀도와 생물량
  3.3. 형태적인 특징과 잎 성장
  3.4. 환경요인과 생물학적 요인과의 관계
 4. 고 찰
 5. 결 론
 참고문헌

• 이상용(국립수산과학원 해조류바이오연구센터) | Sang-Yong Lee (National Fisheries Research & Development Institute)
• 옥재승(㈜세일이엠에스 기업부설연구소) | Jae-Seung Ok (R&D Center SEILEMS) Corresponding author