Are free-floating planktonic hydroids (Cnidaria, Hydrozoa) common components of the pelagic fauna from the South Brazilian Bight?

作者：Cabral Ana Caroline^*; Nogueira Junior Miodeli; Nagata Renato Mitsuo; Brandini Frederico Pereira

来源：Journal of the Marine Biological Association of the United Kingdom, 2015, 95(8): 1645-1652.

DOI：10.1017/S0025315415000727

• Clytia
• planktonic polyps
• resuspension
• zooplankton
• South-west Atlantic
• Brazil

We analysed 267 zooplankton samples collected in the South Brazilian Bight (SBB; 23-27 degrees S) to determine whether hydroids, typically benthic, are common components of the pelagic SBB. Two species, Clytia arborescens, recorded for the first time in the Atlantic Ocean, and Clytia sp. were identified. While these planktonic hydroids were frequent or relatively so in shallow shelf waters (similar to 23% of the samples <50 m isobaths, and 5% of the samples >100 m), abundances were low (up to 61 hydranths m(-3)) suggesting a low trophic impact. Such colonies are probably fragments of benthic colonies detached by storms and/or tides. Given the good condition of the coenosarc, existence of gastric content, and presence of reproductive structures, development of these species appears to be normal in the pelagic environment. Existence in the plankton may increase their capacity for dispersion.

• 出版日期2015-12