Seasonal and spatial variability of dominant copepods along a transect off Walvis Bay (23°S), Namibia

  • F C Hansen Baltic Sea Research Institute, Seestrasse 15, D-18119 Rostock, Germany
  • R R Cloete National Marine Information and Research Centre, Ministry of Fisheries and Marine Resources, PO Box 912, Swakopmund, Namibia
  • H M Verheye Marine & Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2, Rogge Bay 8012, Cape Town, South Africa
Keywords: calanoid copepods, Calanoides carinatus, Metridia lucens, northern Benguela, upwelling

Abstract

The study provides the first quantitative analysis of changes in zooplankton abundance and community structure in the Walvis Bay area, off Namibia, over a full seasonal cycle (February–December 2000). Zooplankton was collected monthly along a 90-nautical-mile transect. Calanoid copepods were numerically the most abundant mesozooplankton, Metridia lucens, Calanoides carinatus, Rhincalanus nasutus and Centropages brachiatus being the most common species, with each exhibiting a specific distribution pattern. Mean calanoid copepod abundance was lower during autumn, when upwelling was minimal, than during other times of the year. However, abundances were exceptionally low in September, when upwelling was most intense. Offshore transport is believed to be responsible for copepod losses from the area during that period. Abundances of C. carinatus and R. nasutus were high inshore between June and August, at the onset of the upwelling season, and peaked during October–December, towards the end of the upwelling season. These cool-water species were closely associated with upwelled water near the coast. The results concur with previous distribution patterns of zooplankton and their association with upwelling in Namibian waters. Findings suggest a possible decadescale shift in the zooplankton community structure since the 1960s.

African Journal of Marine Science 2005, 27(1): 55–63
Published
2005-06-30
Section
Articles

Journal Identifiers


eISSN: 1814-2338
print ISSN: 1814-232X