Dissolved Oxygen and Thermal Regimes of a Ugandan Crater Lake
Document Type
Article
Publication Date
1998
Keywords
Anoxic hypolimnion, Heat budget, Hypoxia, Productivity, Stability, Stratification, Volcanic crater lake
Digital Object Identifier (DOI)
https://doi.org/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-2 d-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.
Citation / Publisher Attribution
Hydrobiologia, v. 385, issue 1-3, p. 201-211
Scholar Commons Citation
Chapman, Lauran J.; Chapman, Colin A.; Crisman, Thomas L.; and Nordlie, Frank G., "Dissolved Oxygen and Thermal Regimes of a Ugandan Crater Lake" (1998). School of Geosciences Faculty and Staff Publications. 1705.
https://digitalcommons.usf.edu/geo_facpub/1705