Skip to main content

Zooplankton abundance and composition in the hypertrophic Rietvlei Dam, South Africa, negate prospects for its remedial ‘top-down’ biomanipulation

Buy Article:

$55.00 plus tax (Refund Policy)

Crustacean zooplankton abundance and composition were determined at one offshore and three nearshore sites in the hypertrophic Rietvlei Dam on 19 dates between July 2009 and December 2011. Total biomass fluctuated seasonally, generally declining from spring to winter through the annual cycle, but also appeared to decline progressively through the study. On overall average, total biomass was high (0.51 mg l–1 or 2.39 g m–2 DW), with Daphnia accounting for ∼40%. Total volumetric biomass was invariably higher in shallow nearshore than offshore locations (average time-paired ratio = 8.1), with comparably large-bodied Daphnia (geometric mean ∼1.2 mm, largest individuals ∼1.75 mm) in both habitats, contra-indicating substantive opportunistic zooplanktivory by juvenile fish. Zooplankton was dominated numerically (ind. l–1, overall average values) by cyclopoid copepods, mostly Thermocyclops (47.1 nauplii and 86.5 copepodites), plausibly favoured by their selective raptorial feeding mode. Cladoceran densities were lower — Daphnia (25.0), Bosmina (7.1), Ceriodaphnia (2.9) and sporadically occurring Moina and Chydorus (<0.5). Seasonal replacement of Daphnia by small-bodied cladocerans during late summer and into autumn was evident in near-monthly samples between July 2009 and June 2010. The findings reflect negligible zooplanktivory in Rietvlei, ruling out top-down biomanipulation prospects for its remedial management.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
No Metrics

Keywords: crustacean zooplankton; eutrophication management; food web manipulation; reservoir ecosystem; seasonal variability

Document Type: Research Article

Affiliations: School of Life Sciences,University of KwaZulu-Natal, Private Bag X01Scottsville,3209, South Africa

Publication date: 2012-11-01

More about this publication?
  • Co-Published by NISC and Taylor & Francis - Subscriber access available here
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more