Abstract
Kelps usually form sori on their vegetative blades or sporophylls, and occasionally on stipes, with a notable exception being the primitive kelp Aureophycus aleuticus (Aureophycaceae), which forms sori on its discoid (haptera-free) holdfast. Here we reveal sorus formation on the holdfast (and blade and stipe) of the warm temperate annual kelp Ecklonia radicosa (Lessoniaceae), whose holdfast is formed by haptera, as is typical of the Laminariales. Surprisingly, hapteral sori continued to release zoospores until December, following blade loss in October. Such production of sori on holdfasts may be advantageous for surviving higher water temperatures and grazing pressure in warm temperate waters.
About the authors
Shingo Akita is a PhD candidate working with on a JSPS fellowship for young scientists at Tokyo University of Marine Science and Technology in Tokyo, Japan. He has studied ecology of Ecklonia radicosa during his Master’s course and genetic diversity of kelps. His research interests include ecology of kelps, herbivorous fish and deforestation.
Hirokazu Yamada is currently a researcher at the Suruga-Bay Deep Seawater Aquaculture Research Center of Shizuoka Prefectural Research Institute of Fishery in Shizuoka, Japan. His recent research is focused on restoration of seaweed beds in non-urchin barrens.
Madoka Ito is a group leader in the Fishery Management Division, Shizuoka Prefecture, Japan. His research interests include marine ecology and crustaceans.
Michael H. Graham is a Professor at Moss Landing Marine Laboratories. He is an experimental ecologist interested in the population biology of habitat-forming species, and the role that variability in the population dynamics and biogeography of these species plays in regulating the ecology and evolution of their associated communities. His research program currently focuses on seaweed-based systems (primarily kelps).
Daisuke Fujita is an Associate Professor at Tokyo University of Marine Science and Technology, Tokyo, Japan. He is a marine ecologist and phycologist and has worked on the ecology of deforestation and restoration of seaweed beds for more than 35 years. His recent research focuses on potential vegetation in urchin barrens.
Acknowledgments
The authors thank Akira Sasaki, Kunihiro Shirai and Naoki Iida for their assistance in SCUBA survey and colleagues in the laboratory for their advice during the sample treatments.
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