title for amphipod section of A SNAIL'S ODYSSEY
  Reproduction & dispersal
  black dot


  The topic of reproduction & dispersal is divided into a section on dispersal, considered here, and sections on LIFE CYCLE, MATE SELECTION COPULATION & FERTILISATION, and BROOD CHAMBER, considered in other sections.
  black dot
Research study 1

photograph of green alga Ulva stranded by the tideDispersal in benthic amphipods is mostly limited to swimming and crawling and, for small individuals, floating, with “rafting” on drifting algal mats also occurring.  Counts of invertebrates in drift-algae samples originating from mudflats in San Juan Island, Washington in summer show that amphipods comprise more than 50% of the total number.  The author speculates that the geographic distribution of brooding species of invertebrates may generally be correlated with rafting opportunities.  Highsmith 1985 Mar Ecol Prog Ser 25: 169.

NOTE  of 1287 invertebrates present in 24 floating algal mats (consisting mainly of the green algae Ulva and Monostroma), amphipods represent 656.  Other invertebrates present are taneids, shrimps, polychaetes, gastropods, and other small species

Green alga Ulva sp. stranded by the
tide on a sand-mud flat will soon be
lifted off by the incoming tide,
carrying with it any attached animals

  black dot
Research study 2

photograph of amphipod Caprella muticamap of Alaska showing distribution of invasive species of amphipod Caprella muticaAs implied in Research Study 1 above, without a free-living larval stage widespread dispersal of amphipods may be mainly by rafting or other kinds of whole-body transport. This could occur across whole oceans or, in the case of the recent invasion of the caprellid amphipod Caprella mutica into Alaska, just a relatively short trip northwards from its known range along the west coast of North America. Researchers from the Smithsonian Environmental Research Center, Maryland recently report finding C. mutica at 4 sites from southeast Alaska to Dutch Harbor in the west Aleutians over 5 collecting seasons (see map) They state that its presence in the Aleutian Islands is the first reported occurrence of a non-native marine species in this part of Alaska. Ashton et al. 2008 Aquatic Biol 3: 133. Photograph courtesy C. Buschbaum, Germany.

NOTE Caprella mutica is indigenous to sub-boreal northeastern Asia. Its first recorded appearance on the west coast of North America was in 1973 in Humboldt Bay, California

  black dot