The benthic deep-water siphonophore Rhodalia miranda and other coelenterates in the south-west Atlantic: ecological and oceanographical implications

Abstract

The benthic deep-water siphonophore Rhodalia miranda was collected for the first time in 1876 by H.M.S. 'Challenger' off the Rio de la Plata estuary beneath the Subtropical Convergence at about 1000 m depth.Rhodalia was reported again about 100 years later from certain distant localities in the subantarctic region of the south-west Atlantic. Hydrographic and topographic features that may be involved in creating this peculiar distribution pattern are discussed together with a likely mode of dispersal of benthic coelenterates. The disjunct distribution of Rhodalia and other benthos of the upper Argentine Slope suggests the subsurface oceanographic rgime to be quite different from what we know of the surface layers.

Distribution patterns of Chilean shallow-water sea anemones (Cnidaria: Anthozoa: Actiniaria, Corallimorpharia); with a discussion of the taxonomic and zoogeographic relationships between the actinofauna of the South East Pacific, the South West Atlantic and the Antarctic

“…The unusual, disjunct distribution pattern of three Argentinean sea anemone species (see Table 2) (Riemann-Zürneck, 1973;1986) is already known from other benthic coelenterates that inhabit the Argentinean continental shelf, e.g. the siphonophore Rhodalia miranda (Riemann-Zürneck, 1991). These species are found south and east of the Falkland (Malvinas) Islands, at the Malvinas Canyon and off Rio de la Plata, south of the Subtropical Convergence (Riemann-Zürneck, 1991).…”

“…the siphonophore Rhodalia miranda (Riemann-Zürneck, 1991). These species are found south and east of the Falkland (Malvinas) Islands, at the Malvinas Canyon and off Rio de la Plata, south of the Subtropical Convergence (Riemann-Zürneck, 1991). These distribution patterns can be explained by the special hydrographic situation of the South West Atlantic.…”

“…1) leads one to expect a comparably low overlap of Pacific and Atlantic shallow water species. The southern part of the Patagonian fjord region, south of Taitao Peninsula, lies under the influence of southward flowing water masses (Cape Horn Current), which flow around the southern tip of South America through the Drake Passage (Pickard, 1973;Brattström and Johanssen, 1983;Riemann-Zürneck, 1986;1991;Castilla et al, 1993;Strub et al, 1998). The relatively shallow layer of water rounding the South American continent turns north or north-east, partly sweeps over the Burdwood Bank and the Falkland Shelf (Riemann-Zürneck, 1991) and then crosses the Falkland Plateau (Fig.…”

A record of deep-water benthic siphonophore (Siphonophorae: Physonectae: Rhodaliidae) in vicinity of submarine Piyp Volcano (North-Western Pacific)

“…1A), или почти шарообразные (рис. 1B-E) колонии диаметром около 6 ции и современные авторы (Pugh, 1983;Riemann-Zürneck, 1991). Еще один интересный факт, на который обратил внимание Паг: к моменту написания его монографии (Pugh, 1983) родалииды были известны в литературе, за одним исключением, только по экземплярам, собранным старыми экспедициями до 1908 г.…”