Physical and chemical limnology of alpine lakes and pools in the Rwenzori Mountains (Uganda-DR Congo)

This study describes the physical and chemical properties of 17 Afroalpine lakes (> 2 m deep) and 11 pools (< 2 m deep) in the Rwenzori mountains, Uganda-DR Congo, with the aim to establish the baseline conditions against which to evaluate future environmental and biological changes in these u...

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Bibliographic Details
Published in:Hydrobiologia
Main Authors: Eggermont, Hilde, Russell, James M, Schettler, Georg, Van Damme, Kay, Bessems, Ilse, Verschuren, Dirk
Format: Article in Journal/Newspaper
Language:English
Published: 2007
Subjects:
Biology and Life Sciences
afro-alpine zone
alpine lakes
climate change
east African mountains ~
limnology
pools
rwenzori
water chemistry
FRESH-WATER ECOSYSTEMS
CLIMATE-CHANGE
ACID DEPOSITION
CRITICAL LOADS
UV-RADIATION
ARCTIC LAKES
2 CENTURIES
BREAK-UP
TEMPERATURE
CHEMISTRY
Arctic
Clearwater Lakes
Climate change
Online Access:https://biblio.ugent.be/publication/414235
http://hdl.handle.net/1854/LU-414235
https://doi.org/10.1007/s10750-007-0741-3
https://biblio.ugent.be/publication/414235/file/4134592
Description
Summary:This study describes the physical and chemical properties of 17 Afroalpine lakes (> 2 m deep) and 11 pools (< 2 m deep) in the Rwenzori mountains, Uganda-DR Congo, with the aim to establish the baseline conditions against which to evaluate future environmental and biological changes in these unique tropical ecosystems, and to provide the foundation for lake-based paleoenvironmental studies. Most Rwenzori lakes are located above 3,500 m elevation, and dilute (5-52 mu S/cm specific conductance at 25 degrees C) open systems with surface in- and outflow. Multivariate ordination and pairwise correlations between environmental variables mainly differentiate between (1) lakes located near or above 4,000 m (3,890-4,487 m), with at least some direct input of glacial meltwater and surrounded by rocky catchments or alpine vegetation; and (2) lakes located mostly below 4,000 m ( 2,990 4,054 m), remote from glaciers and surrounded by Ericaceous vegetation and/or bogs. The former group are mildly acidic to neutral clearwater lakes ( surface pH: 5.80-7.82; Secchi depth: 120-280 cm) with often above-average dissolved ion concentrations (18-52 mu S/cm). These lakes are (ultra-) oligotrophic to mesotrophic (TP: 3.1-12.4 mu g/l; Chl-a: 0.3-10.9 mu g/l) and phosphorus-limited (mass TN/TP: 22.9-81.4). The latter group are mildly to strongly acidic (pH: 4.30-6.69) waters stained by dissolved organic carbon (DOC: 6.8-13.6 mg/l) and more modest transparency (Secchi-disk depth: 60-132 cm). Ratios of particulate carbon, particulate nitrogen and chlorophyll a in these lakes indicate that organic matter in suspension is primarily derived from the lakes' catchments rather than aquatic primary productivity. Since key features in the Rwenzori lakes' abiotic environment are strongly tied to temperature and catchment hydrology, these Afroalpine lake ecosystems can be expected to respond sensitively to climate change and glacier melting.

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