, Volume 770, Issue 1, pp 15–26

Impact of sea spider parasitism on host clams: relationships between burial patterns and parasite loads, somatic condition and survival of host

  • Takeshi Tomiyama
  • Katsumasa Yamada
  • Kunihiro Wakui
  • Masanori Tamaoki
  • Katsumi Miyazaki
Primary Research Paper

DOI: 10.1007/s10750-015-2564-y

Cite this article as:
Tomiyama, T., Yamada, K., Wakui, K. et al. Hydrobiologia (2016) 770: 15. doi:10.1007/s10750-015-2564-y


A sudden outbreak of the parasitic sea spider Nymphonella tapetis accompanied by mass mortality of the Manila (asari) clam Ruditapes philippinarum was observed in Japan in 2007. It was unknown why dead and dying clams were found on the sand surface. In our laboratory experiment, in which sea spiders were artificially parasitised to host clams, unburied clams were significantly increased, suggesting that sea spider parasitism can change the burial mode of clams. We compared parasite loads, somatic condition and reburial activity of Manila clams among three burial groups (fully buried, partly buried and unburied) collected from the field. Unburied and partly buried clams had 30% lower soft body weight and 60% lower adductor strength as compared to the fully buried clams. Parasite prevalence and the mean infection intensity were greater in unburied and partly buried clams than in fully buried clams. Reburial depth was smaller in unburied and partly buried clams than in fully buried clams under laboratory conditions. Approximately 30% of the unburied and partly buried clams died during 30 days, whereas fully buried clams suffered no mortality. These results indicate that sea spider parasitism can reduce the burial depth and somatic condition of host clams, and eventually cause clam mortality on the sand.


Clam fishery Host-parasite interaction Pycnogonid Tidal flat management Sublethal impact 

Funding information

Funder NameGrant NumberFunding Note
Society for the Promotion of Science (JP)
  • KAKENHI Grant Number 26292105

Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  1. 1.Soma BranchFukushima Prefectural Fisheries Experimental StationSomaJapan
  2. 2.Research Centre for Fisheries and Environment in the Ariake and Yatsushiro Bay, Seikai National Fisheries Research InstituteFisheries Research AgencyNagasakiJapan
  3. 3.Center for Environmental Biology and Ecosystem StudiesNational Institute for Environmental StudiesTsukubaJapan
  4. 4.Seto Marine Biological Laboratory, Field Science Education and Research CenterKyoto UniversityShirahamaJapan
  5. 5.Graduate School of Biosphere ScienceHiroshima UniversityHigashi-HiroshimaJapan

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