Assemblages of hydroids (Cnidaria) from three seamounts near Bermuda in the western North Atlantic |
| |
| Institution: | 1. V.I. Il’ichev Pacific Institute of Oceanography, Far East Branch of the Russian Academy of Sciences, ul. Baltiyskaya 43, Vladivostok, 690041, Russia;2. A. V. Zhirmunsky Institute of Marine Biology, Far East Branch of the Russian Academy of Sciences, ul. Palchevskogo 17, Vladivostok, 690041, Russia |
| |
| Abstract: | Three seamounts flanking the oceanic island of Bermuda were sampled for hydroids. Collecting was undertaken by submersible (SDL-1) and by dredge at depths between 48 and 107 m on the summits of Argus and Challenger banks. A shallower collection (<20 m) from the pilings of a tower on Argus Bank was made using SCUBA. Major bottom types on both banks were aggregations of rhodoliths, limestone reefs, and areas of calcareous sand. Hydroids were ubiquitous, but quite sparse, on firm substrata. None was collected on sandy bottoms. Of 45 species identified from the two oceanic banks, over half (25) were found on both. On Bowditch Seamount, samples were obtained at depths between 1285 and 1381 m by dredge and grab. Of four species found, only one (Filellum serratum) occurred in shallower collections from Argus and Challenger banks. Most species (43 of 48) from the three seamounts have been reported elsewhere in the Western Atlantic Tropical region, and many (38 of 48) are known from Bermuda. No endemics were discovered, and no relicts or exotics were recognized. Gonophores in >70% of the species are fixed sporosacs instead of free medusae. This conforms with a hypothesis that invertebrates of oceanic islands and seamounts tend to have short-lived pelagic larval stages, ensuring the greatest retention and conservation of propagules. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
