Diversity and taxonomy of intertidal Bryozoa (Cheilostomata) at Akkeshi Bay, Hokkaido, Japan

Publication Type:Journal Article
Year of Publication:2007
Authors:A. V. Grischenko, Dick, M. H., Mawatari, S. F.
Journal:Journal of Natural History
Type of Article:Review
ISBN Number:0022-2933
Accession Number:ISI:000247967500005
Keywords:biodiversity, biogeography, bryozoa, Cheilostomata, genus, intertidal, islands, new, species, species richness, taxonomy

We found 39 cheilostome species among more than 7000 specimens collected at 10 intertidal sites in rocky habitats along the shore of Akkeshi Bay, eastern Hokkaido Island, Japan. These species are herein described in detail and illustrated by scanning electron microscopy. Nine species (23% of total) are described as new (Electra asiatica, Callopora sarae, Conopeum nakanosum, Cauloramphus cryptoarmatus, Cauloramphus multispinosus, Cauloramphus niger, Stomachetosella decorata, Microporella luellae, and Celleporina minima), and 21 species (54%) are reported for the first time from Japan. Species richness ranged from eight to 29 species per study site. A TWINSPAN analysis showed the species fell into nine groups defined by the local pattern of distribution. A cluster analysis of study sites based on similarity of species composition showed three faunistic groups distributed geographically: in Akkeshi Lake, along the eastern-central shore of the bay, and at the mouth of the bay. Species richness in estuarine Akkeshi Lake was low, with a species composition very different from the outer bay. Most cheilostomes were found on rock and shell substrata, but uncommonly occurred on concrete walls, algae, hydroids, tubes of polychaetes, other bryozoans, and anthropogenic debris. Of the 39 species found, 33 (85%) contained embryos during the collecting periods, 2-7 June and 3-6 July 2004. The biogeographical composition of intertidal cheilostomes at Akkeshi Bay included species with Arctic-Boreal (28%), Boreal (59%), and Boreal-Subtropical (13%) distributions. The overall species richness of intertidal cheilostomes was two-thirds that documented intertidally in a comparable study at Kodiak, Alaska, a locality 15 degrees higher in latitude. We attribute the lower richness at Akkeshi to differences in the nearshore marine environment between the two localities.

URL:<Go to ISI>://000247967500005
Alternate Journal:J. Nat. Hist.
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