Growth dynamics of the seagrass, Zostera marina in Jindong Bay on the southern coast of Korea

Growth dynamics of the seagrass, Zostera marina were examined at the two stations (Myungju and Dagu) in Jindong Bay on the southern coast of Korea. Eelgrass leaf productivities, underwater irradiance, water temperature, dissolved inorganic nitrogen (DIN) in water column and sediments, and tissue carbon (C) and nitrogen (N) content were monitored monthly from March 2002 to January 2004. Underwater irradiance fluctuated highly without a clear seasonal trend, whereas water temperature showed a distinct seasonal trend at both study stations. Water column DIN concentrations were usually less than $5{\mu}M$ at both study sites. Sediment pore water $NH_4{^+}$ and $NO_3{^-}+NO_2{^-}$ concentrations were higher at the Myungju site than at the Dagu site. Eelgrass leaf productivity at both study sites exhibited a distinct seasonality, increasing during spring and decreasing during summer. Seasonal variation of eelgrass productivity was not consistent with seasonal patterns of underwater irradiance, or water temperature. Eelgrass tissue C and N content at both study sites also showed significant seasonal variations. Relationships between tissue C and N content and leaf productivities exhibited usually negative correlations at both study sites. These negative correlations implied that the growth of Z. marina at the study sites was probably limited by C and N supplies during the high growth periods.