Aquatic Ecology

, Volume 43, Issue 2, pp 359–370 | Cite as

Genetic variation and structure of the endangered freshwater benthic alga Marimo, Aegagropila linnaei (Ulvophyceae) in Japanese lakes

  • Akiko SoejimaEmail author
  • Natsuko Yamazaki
  • Takako Nishino
  • Isamu Wakana


Aegagropila linnaei is a freshwater green alga of the order Cladophorales, which is well known as ‘Marimo’ in Japan for its beautiful spherical form as lake balls in Lake Akan. Lake Akan is the only lake in which spherical ‘Marimo’ is found in Japan, but the species also grows as floating or epilithic filaments which appear in several other Japanese lakes. The spherical growth form usually reproduces vegetatively, and it is not known if the species also reproduces sexually or whether transformation between different growth forms happens in natural populations. In this study, the genetic diversity of A. linnaei in Japan was investigated using isozyme analysis. Apart from one colony in Lake Ogawara, each colony was genetically homogeneous, which suggests that asexual reproduction is dominant. All the non-epilithic (spherical aggregations, floating filaments, and floating tufts) colonies in Lake Akan were genetically similar, regardless of the location of sites within the lake, while epilithic colonies have different genetic structures. Therefore, transformation or gene flow between epilithic and non-epilithic forms is not evident in natural populations. Because the genetic diversity largely depends on epilithic algae in Lake Akan, it is important to conserve epilithic- as well as spherical-colonies.


Aegagropila linnaei Conservation Endangered plant Freshwater algae Genetic variation Isozyme ‘Marimo’ 



We are grateful to Shogo Arai for collecting samples from Lake Ogawara, and Dr. Takeaki Hanyuda for offering samples and suggestions. Thanks are due to Minori Zenitani and Yoshifumi Kishimoto for their kind help in preparation of materials at the lab and many good advices. Special thanks are due to Dr. Arni Einarsson and Dr. Michael O. Dillon for their precise reading and comments on the manuscript.


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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Akiko Soejima
    • 1
    Email author
  • Natsuko Yamazaki
    • 2
  • Takako Nishino
    • 1
  • Isamu Wakana
    • 3
  1. 1.Osaka Prefecture UniversitySakai, OsakaJapan
  2. 2.Osaka Medical Center and Research Institute for Maternal and Child HealthIzumi, OsakaJapan
  3. 3.Lake Akan Eco-Museum CenterAkan, HokkaidoJapan

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