Diel activity and vertical distribution of Lysianassoid amphipods dominant in Onagawa Bay, north-eastern Japan

Atsushi Takekawa, Koichi Sasaki, Michio Omori

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Baited traps were used over 24 h to reveal the diel activity and vertical distribution of three dominant lysianassoid amphipods (Scopelocheirus onagawae, Anonyx omorii, Anonyx abei) in Onagawa Bay, north-eastern Japan. The three species were the most dominant small crustacean scavengers in the bay. Most individuals were caught by traps deployed 0.3 m above the bottom, showing that they were active in the layers close to the sea bottom. No habitat segregation was found among species or developmental stages, suggesting that these scavengers rely on the food supply from bottom deposits. The three species increased remarkably in numbers of collected individuals at night, showing a rise in feeding activity. The two Anonyx species were collected only during the night, and S. onagawae was collected mostly during the night. The nocturnal activity appears to be an adaptation to reduce predation risks. However, juveniles of S. onagawae appeared even during the day, suggesting that feeding might take precedence over avoiding predation. Baited traps collected ovigerous females of S. onagawae but not of Anonyx species; the reason for the difference could not be determined.

Original languageEnglish
Pages (from-to)971-977
Number of pages7
JournalFisheries Science
Volume70
Issue number6
DOIs
Publication statusPublished - 2004 Dec 1

Keywords

  • Anonyx abei
  • Anonyx omorii
  • Balted trap
  • Diel activity
  • Lysianassoid amphipod
  • Scavenger
  • Scopeiocheirus onagawae

ASJC Scopus subject areas

  • Aquatic Science

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