Hydrobiologia

, Volume 385, Issue 1–3, pp 201–211

Dissolved oxygen and thermal regimes of a Ugandan crater lake

  • Lauren J. Chapman
  • Colin A. Chapman
  • Thomas L. Crisman
  • Frank G. Nordlie
Article

DOI: 10.1023/A:1003527016384

Cite this article as:
Chapman, L.J., Chapman, C.A., Crisman, T.L. et al. Hydrobiologia (1998) 385: 201. doi:10.1023/A:1003527016384

Abstract

This paper quantifies the temporal pattern of thermal stratification and deoxygenation in Lake Nkuruba, a small (3 ha), deep (maximum depth = 38 m) crater lake in western Uganda. Dissolved oxygen penetrated to an average depth of 9 m and a maximum depth of 15 m below which the lake was permanently anoxic over the 2 years of study. Although surface oxygen levels were correlated with both surface water temperature and rainfall, seasonal cycles of dissolved oxygen were not well-defined and may have been obscured by the high frequency of short-term fluctuations and by inter-annual variations caused by shifts in rainfall.

Surface water temperature averaged 23.3±0.7 °C (S.D.) and varied directly with air temperature. Both diurnal changes and top-bottom temperature differentials were small averaging 1.7±0.7 °C and 1.6±0.8 °C, respectively. Thermal stability ranged from 101.3 to 499.9 g-cm cm-2 and was positively related to surface water temperature suggesting that this small protected lake responds rapidly to short-term meteorological changes. Because contribution to the annual heat exchange cycle was confined to upper waters, the lake's annual heat budget was low, 1,073.8 cal cm-2 yr-1. However, net primary productivity was relatively high averaging 1.3 g C m-2d-1.

The region where Lake Nkuruba is situated experienced a very strong earthquake (6.2 on the Richter scale) on 4 February, 1994. Subsequently, water levels dropped markedly in the lake, falling 3.14 m over a 5-month period.

hypoxia anoxic hypolimnion volcanic crater lake stratification productivity heat budget stability 

Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • Lauren J. Chapman
    • 1
    • 2
  • Colin A. Chapman
    • 1
  • Thomas L. Crisman
    • 3
  • Frank G. Nordlie
    • 1
  1. 1.Department of ZoologyUniversity of FloridaGainsvilleU.S.A
  2. 2.Wildlife Conservation SocietyBronxU.S.A.
  3. 3.Center for Wetlands, Department of Environmental Engineering SciencesUniversity of FloridaGainsvilleU.S.A

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