Hydrobiologia

, Volume 317, Issue 3, pp 177–182 | Cite as

Caridina nilotica in Lake Victoria: abundance, biomass, and diel vertical migration

  • John T. Lehman
  • Godfrey B. Mbahinzireki
  • Lucas Mwebaza-Ndawula
Article

Abstract

Caridina nilotica (Decapoda: Atyidae) in offshore waters of Lake Victoria were investigated with both day and night sampling over a period of two years. Offshore populations are mainly planktonic rather than benthic, and the animals exhibit diel vertical migrations into near-surface waters at night. These changes in diel abundance as well as the size-frequency distribution of the migrating shrimp suggest that the migratory behavior is in response to visual planktivory, because only the very smallest individuals (2–4 mm) remain in surface waters during the day. During October 1992, abundances were estimated both by vertical net sampling and by underwater video transect methods. Concordance was established between abundances estimated by the two methods. Only about 9% (night) to 14% (day) of the Caridina population appeared to be epibenthic. We suggest that the behavior of the animal is consistent with the hypothesis that it is not a strict detritivore as previously reported; rather it may engage in facultative planktivory, especially at night.

Key words

zooplankton biomass Lake Victoria diel vertical migration Caridina Chaoborus 

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Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • John T. Lehman
    • 1
  • Godfrey B. Mbahinzireki
    • 2
  • Lucas Mwebaza-Ndawula
    • 2
  1. 1.Department of Biology and Center for Great Lakes and Aquatic Science, Natural Science BuildingUniversity of MichiganAnn ArborUSA
  2. 2.Uganda Fisheries Research InstituteJinjaUganda

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