title: Reconstruction of historical nutrient levels in Korean and Japanese coastal areas based on dinoflagellate cyst assemblages.
abstract: Dinoflagellate cysts acquired from sediment cores were analyzed in order to reconstruct historical nutrient levels in Gamak Bay, Korea and Ariake Bay, Japan. Dinoflagellate cyst assemblages in Gamak Bay were characterized by high proportions of heterotrophic cysts such as Brigantedinium spp., Protoperidinium americanum and Polykrikos cysts, which suggested that nutrients levels may have already been high before 1970s, and then increased further to the hypertrophic conditions of the 1990s. In contrast, dinoflagellate cyst assemblages in Ariake Bay were characterized by high relative abundances of Lingulodinium machaerophorum and Spiniferites spp., which suggested that nutrient levels in Ariake Bay had increased gradually since the mid 1960s, and may have been significantly enhanced by the mid 1980s. Dinoflagellate cyst assemblages reflecting environmental changes in the two bays are contrasting, perhaps due to different nutrient enrichment mechanisms. This suggests that the indicators of nutrient levels encoded in dinoflagellate cyst assemblages may exhibit site-specific information.
authors.affiliation: Coastal Ecological Processes Research Division, South Sea Institute, KORDI, Geoje 656-830, Republic of Korea.
authors.forename: Hyeon Ho
authors.initials: HH
authors.lastname: Shin
authors.forename: Koichiro
authors.initials: K
authors.lastname: Mizushima
authors.forename: Seok Jin
authors.initials: SJ
authors.lastname: Oh
authors.forename: Jong Sick
authors.initials: JS
authors.lastname: Park
authors.forename: Il Hyeon
authors.initials: IH
authors.lastname: Noh
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Iwataki
authors.forename: Kazumi
authors.initials: K
authors.lastname: Matsuoka
authors.forename: Yang Ho
authors.initials: YH
authors.lastname: Yoon
mesh_terms: D044822:Biodiversity; D004141:Dinoflagellida / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification*; D004784:Environmental Monitoring / Q000379:methods*; D007564:Japan; D007723:Korea; D012623:Seawater; D014873:Water Pollutants / Q000032:analysis*; D014876:Water Pollution / Q000706:statistics & numerical data*
chemical_list: D014873:Water Pollutants