Observations on the Diel Vertical Distribution of Hydromedusae in the Southern Benguela

Buecher, Emmanuelle; Gibbons, Mark J.

doi:10.2989/18142320309504012

Cited by 12 publications

(13 citation statements)

References 33 publications

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“…The planktic data were collated primarily from the studies of Pagès (as detailed in Pagès et al. , 1992), Buecher & Gibbons (2000, 2003), Buecher et al. (2005), Gibbons & Buecher (2001), Sparks & Gibbons (2003), Gibbons & Thibault‐Botha (2002) and Thibault‐Botha et al.…”

Section: Methodsmentioning

confidence: 99%

Patterns in marine hydrozoan richness and biogeography around southern Africa: implications of life cycle strategy

Gibbons

Buecher

Thibault

et al. 2010

Journal of Biogeography

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Aim To examine patterns of marine hydrozoan richness around southern Africa and to test the hypothesis that patterns of biogeography become weaker with increasing dispersal ability.Location The coastline of southern Africa from 21°S, 14°E to 28°S, 33°E, extending from the intertidal zone seawards a distance of 200 nautical miles.Methods Published and unpublished information on the distribution of marine Hydrozoa was entered as presence/absence data onto a gridded coastline of the region. A similarity matrix between the species composition of grid squares was constructed using the Bray-Curtis index and visualized using non-metric multidimensional scaling ordinations. Separate analyses were conducted, and compared, on the three major life cycle groupings: holoplanktic, meroplanktic and benthic.Results Over 450 species of marine Hydrozoa have been reported from the region, and species richness increases eastwards, in a manner at odds with the distribution of sampling effort. There was a significant correlation between the geographic structures of the resemblance matrices generated for the three life cycle groupings. In other words, all three groups showed similar patterns of biogeography around the region, and these were broadly similar to those reported by others. However, there were differences between them that reflect the resolution at which the data were examined. At a level of 40% similarity, there was no biogeographic structure to the holoplanktic fauna, the meroplanktic taxa were simply sub-divided into cool-and warm-temperate/subtropical elements, and in the case of benthic taxa, the cool-water fauna was further split into a southern Namaqua and a depauperate northern Namib component. Even at a resolution of 70% similarity, the holopelagic taxa could be separated only into cool-temperate and warm-temperate/subtropical faunas.Main conclusions Holoplanktic taxa show comparatively less biogeographic structure than meroplanktic taxa, which in turn show less clearly defined biogeographic structure than benthic taxa. It is suggested that this is related to the interaction between oceanography and dispersive-stage duration. The role that the Agulhas Current plays in influencing the Benguela Current fauna is highlighted. This study has implications for conservation planning exercises based on protecting representative biotopes in different biogeographic regions.

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Section: Methodsmentioning

confidence: 99%

Patterns in marine hydrozoan richness and biogeography around southern Africa: implications of life cycle strategy

Gibbons

Buecher

Thibault

et al. 2010

Journal of Biogeography

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“…Youngbluth & Båmstedt (2001) observed that swimming rates and feeding activity of the mesopelagic coronate medusa Periphylla periphylla in a Norwegian fjord varied with age and time of the day. Buecher & Gibbons (2003) investigated DVM of six common hydromedusae at two stations (168 and 71 m deep) in St Helena Bay on the west coast of South Africa in 3‐ and 6‐day surveys. The depth distribution and amplitude of migration varied between surveys for most species, so definitive interpretations of pattern could not be made.…”

Section: Problemmentioning

confidence: 99%

Diel vertical migration of medusae in the open Southern Adriatic Sea over a short time period (July 2003)

et al. 2009

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ProblemDiel vertical migration (DVM) occurs in a wide range of zooplankton taxa and probably represents the biggest animal migration, in term of biomass, on the planet (Hays 2003). Of the many factors proposed to explain this behavior, the principal attention has been given to light intensity and several hydrographic variables, especially temperature, and how DVM may benefit feeding, predator avoidance, and reproduction (e.g. Longhurst 1985;

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“…However, there is a single observation of Plotocnide sp. from New Zealand (Barnett 1985) and a record of Plotocnide incertae (Linko, 1900) from off the southern tip of Africa (Buecher et al 2005). That said, Kramp (1942) suggested that P. incertae is most likely referable to a separate genus in the family Tubulariidae.…”

Section: Resultsmentioning

confidence: 99%

DNA barcodes unite two problematic taxa: the meiobenthic Boreohydra simplex is a life-cycle stage of Plotocnide borealis (Hydrozoa: Aplanulata)

Pyataeva

Hopcroft

Lindsay

et al. 2016

Zootaxa

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Genetic barcodes of arctic medusae and meiobenthic cnidarians have uncovered a fortuitous connection between the medusa Plotocnide borealis Wagner, 1885 and the minute, mud-dwelling polyp Boreohydra simplex Westblad, 1937. Little to no sequence differences exist among independently collected samples identified as Boreohydra simplex and Plotocnide borealis, showing that the two different forms represent a single species that is henceforth known by the older name Plotocnide borealis Wagner, 1885. The polyp form has been observed to produce bulges previously hypothesized to be gonophores, and the results here are consistent with that view. Interestingly, the polyp has also been reported to produce egg cells in the epiderm, a surprising phenomenon that we document here for only the second time. Thus, P. borealis produces eggs in two different life stages, polyp and medusa. This is the first documented case of a metagenetic medusozoan species being able to produce gametes in both the medusa and polyp stage. It remains unclear what environmental/ecological conditions modulate the production of eggs and/or medusa buds in the polyp stage. Similarly, sperm production, fertilization and development are unknown, warranting further studies.

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Observations on the Diel Vertical Distribution of Hydromedusae in the Southern Benguela

Cited by 12 publications

References 33 publications

Patterns in marine hydrozoan richness and biogeography around southern Africa: implications of life cycle strategy

Patterns in marine hydrozoan richness and biogeography around southern Africa: implications of life cycle strategy

Diel vertical migration of medusae in the open Southern Adriatic Sea over a short time period (July 2003)

DNA barcodes unite two problematic taxa: the meiobenthic Boreohydra simplex is a life-cycle stage of Plotocnide borealis (Hydrozoa: Aplanulata)

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