, Volume 451, Issue 1–3, pp 275–286 | Cite as

Observations on the distribution and relative abundance of the scyphomedusan Chrysaora hysoscella (Linné, 1766) and the hydrozoan Aequorea aequorea (Forskål, 1775) in the northern Benguela ecosystem

  • Conrad Sparks
  • Emmanuelle Buecher
  • Andrew S. Brierley
  • Bjørn Erik Axelsen
  • Helen Boyer
  • Mark J. Gibbons


Observations on the abundance of medusae at the surface were conducted in the northern Benguela ecosystem, over the period August 1997–June 1998. The results suggest that Chrysaora hysoscella is found inshore, whereas Aequorea aequorea tends to be found offshore. Although these relative observations are subject to bias caused by seasonal changes in the survey area, they are generally supported by the results of correlation analyses, and by the results of a more quantitative, cross-shelf trawl survey. Both species of medusae display marked patchiness, and can be very abundant. They appear to have mostly non-overlapping patterns of distribution in the upper layers of the water column, and so are able exert a consistent predation pressure across the width of the continental shelf. The estimates of biomass obtained are used as input variables to existing models of energy flow within the ecosystem.

jellyfish cross-shelf distribution Namibia spatial-partitioning visual observations trawl survey Ecopath 


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Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Conrad Sparks
    • 1
    • 2
  • Emmanuelle Buecher
    • 2
    • 3
  • Andrew S. Brierley
    • 4
  • Bjørn Erik Axelsen
    • 5
  • Helen Boyer
    • 6
  • Mark J. Gibbons
    • 2
  1. 1.Faculty of Applied SciencesCape TechnikonCape TownSouth Africa
  2. 2.Zoology DepartmentUniversity of the Western CapeBellvilleSouth Africa
  3. 3.Laboratoire d'Océanographie Biologique et Ecologie du Plancton MarinCNRS/UPMC 7076. Station ZoologiqueVillefranche-sur-MerFrance
  4. 4.Biological Sciences DivisionBritish Antarctic SurveyCambridgeU.K.
  5. 5.Institute if Marine ResearchBergenNorway
  6. 6.National Marine Information and Research CentreSwakopmundNamibia

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