2010 Volume 5 Issue 2 Pages 62-68
During our survey of the subtidal macrobiota on wave dissipating concrete blocks along the coast of Osaka Bay in 1997, we recorded a species of serpulid polychaete that was not immediately identifiable. In 2007, we re-examined the specimens and discovered that they were identical to Hydroides dianthus, native to the East Coast of North America. The density of the worm in Osaka Bay varied remarkably between sites and depths. A Steel-Dwass multiple comparison analysis was used to evaluate the differences among sites, depths and seasons. Spearman's rank correlation was used to examine the influence of physical factors of temperature, salinity and dissolved oxygen, and biological ones of the densities of coexisting organisms. The results suggest that salinity greater than 30 psu and biological interaction with macroalgae or mussel (Xenostrobus securis) are presently acting as limiting factors for the invasion of H. dianthus.
