Seasonal Variation in Host Utilization of Epiphytic Lacuna Species in Mixed Algal and Surfgrass Stands in Japan |
| |
| Authors: | Makoto Kanamori Seiji Goshima & Hiroshi Mukai |
| |
| Institution: | Laboratory of Biodiversity, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan.; Akkeshi Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Akkeshi 088-1113, Japan.; Present address: Makoto Kanamori, Fisheries Division of the Economic Affairs Department, Kushiro Subprefectural Office, Hokkaido Government, Kushiro 085-8588, Japan. |
| |
| Abstract: | Abstract. On the subtidal rocky shore of Akkeshi Bay, Hokkaido, Japan, the congeneric phytal gastropods, Lacuna uchidai and L. decorata , inhabit the multispecific vegetation consisting of the surfgrass, Phyllospadix iwatensis and the brown alga, Cystoseira hakodatensis . We studied the phenologies of Phyllospadix and Cystoseira , host utilization patterns and life histories of Lacuna spp. to examine how these gastropods accommodate the seasonal fluctuations of the habitat. The preferences for macrophyte by Lacuna spp. were examined by laboratory experiments. The phenologies of macrophytes, the seasonal and between-substrata variations of Lacuna spp. were examined by monthly sampling from Phyllospadix and Cystoseira beds between May 1999 and May 2000. Lacuna uchidai showed significant preference for Phyllospadix , whereas L. decorata had no preference for a particular substratum. Most L. uchidai were collected from the Phyllospadix bed, however L. decorata appeared in both Phyllospadix and Cystoseira beds. The peak of new recruit of L. uchidai coincided with that of Phyllospadix biomass. The synchronization of life cycle with the phenology of the host may be adaptive for using the limited habitat. Seasonal variation in density of L. decorata coincided with neither patterns for Phyllospadix nor Cystoseira . Seasonal variation in density and size frequency distribution suggested L. decorata migrated among adjacent macrophytes. Although it was a little vague, this hypothesis was probably the best explanation of our results. Our study shows that two co-occurring Lacuna species utilize the macrophytes as habitats by the different life histories and utilization patterns and, may be alternatively accommodated to the seasonal fluctuations of their habitats. |
| |
| Keywords: | Life history reproductive traits seasonal variation host utilization epiphyte macrophyte gastropod Lacuna |
|
|
