Eutrophication-induced changes in Lake Nakaumi, southwest Japan

Kota Katsuki, Yasushi Miyamoto, Kazuyoshi Yamada, Hiroyuki Takata, Keiko Yamaguchi, Daisuke Nakayama, Hugo Coops, Hidenobu Kunii, Ritsuo Nomura, Boo Keun Khim

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Lake Nakaumi, southwest Japan, is an enclosed lagoon characterized by polyhaline and halocline conditions. Since the last century, its ecological state has been altered by eutrophication. We used a paleolimnological approach and studied multiple proxies, including chemical compounds, diatoms, foraminifera and molluscs, to infer the eutrophication history of the ecosystem. Eutrophication in Lake Nakaumi was associated with several factors, including increased nutrient loading, input of herbicides, and dike building since the 1920s. The ecological condition of this lake was divided into several stages that reflect the eutrophication process after the 1940s. A catastrophic "regime shift" from a clear state with aquatic vegetation to a turbid one with phytoplankton occurred in the early 1950s. Environmental degradation in the Honjo area, a part of Lake Nakaumi, was attributed primarily to physical changes caused by the construction of an enclosing dike. Eutrophication occurred almost simultaneously with the physical changes to the Honjo area in the 1970s. Until recently, no regime shift was observed in this area, though the core-top sediments show possible symptoms of incipient change.

Original languageEnglish
Pages (from-to)1115-1125
Number of pages11
JournalJournal of Paleolimnology
Volume40
Issue number4
DOIs
Publication statusPublished - 2008 Nov
Externally publishedYes

Keywords

  • Diatoms
  • Ecological shift
  • Foraminifera
  • Lagoon eutrophication
  • Mollusks
  • Sediment core

ASJC Scopus subject areas

  • Aquatic Science
  • Earth-Surface Processes

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  • Cite this

    Katsuki, K., Miyamoto, Y., Yamada, K., Takata, H., Yamaguchi, K., Nakayama, D., Coops, H., Kunii, H., Nomura, R., & Khim, B. K. (2008). Eutrophication-induced changes in Lake Nakaumi, southwest Japan. Journal of Paleolimnology, 40(4), 1115-1125. https://doi.org/10.1007/s10933-008-9217-3