Driving factors of temporary and permanent shallow lakes in and around Hwange National Park, Zimbabwe

Stembile Msiteli-Shumba,Shakki Kativu,Edwin Makuwe,Beaven Utete,Florence D Hulot

doi:10.4314/wsa.v44i2.12

Abstract

Small aquatic ecosystems in semi-arid environments are characterised by strong seasonal water level fluctuations. In addition, land use as well as artificial pumping of groundwater to maintain water resources throughout the dry season may affect the functioning of aquatic ecosystems. In this study, we investigated pans situated in and around Hwange National Park, Zimbabwe, where certain waterholes are artificially maintained during the dry season for conservation purposes. We monitored 30 temporary and permanent waterholes for 7 months across the wet and dry seasons in 2013, and analysed them for standard parameters to investigate seasonal variations, assess the effects of land use and pumping on lake functioning, and determine the driving factors of these aquatic systems. Results show an increase in conductivity, hardness, and turbidity when temporary pans dry up and permanent ones are filled with groundwater. Prominent parameters explaining the diversity of aquatic ecosystems are water hardness, conductivity, turbidity, and the presence of vegetation. Seasonality differences in certain parameters suggest the influence of water level fluctuations associated with rainfall, evaporation, and pumping activities. Further, the distinction between turbid pans and those with clear water and vegetation suggests the alternative functioning of pans. Land use had no significant effects, while the effects of pumping are discussed. In times of water scarcity, animals gather around artificially maintained waterholes and foul water with faeces and urine, thus inducing water eutrophication.

Highlights

Water level fluctuation (WLF) is an important driver of shallow lakes in temperate and tropical zones (Beklioglu et al, 2007; Blaustein and Schwartz, 2001; Coops et al, 2003; Hofmann et al, 2008; Jeppesen et al, 2015; Mustapha, 2008; Schwartz and Jenkins, 2000)
Most research in aquatic ecology focuses on permanent water bodies (Schwartz and Jenkins, 2000), studying the role of WLF in the drying up of ecosystems and their responses is in great need (Coops et al, 2003)
WLF and drying up affect species living in the aquatic–terrestrial transition zones, in particular, littoral helophytes (Riis and Hawes, 2003; Thomas et al, 2000; Thomaz et al, 2006) and benthic invertebrates (Bazzanti et al, 2009; Coops et al, 2003; Strachan et al, 2014; White et al, 2008), as well as organisms living in the pelagic zone (Kelley et al, 2000; Medeiros et al, 2015; Michaloudi et al, 2012; Ovie and Adeniji, 1994; Teferi et al, 2014)

Summary

Introduction

Water level fluctuation (WLF) is an important driver of shallow lakes in temperate and tropical zones (Beklioglu et al, 2007; Blaustein and Schwartz, 2001; Coops et al, 2003; Hofmann et al, 2008; Jeppesen et al, 2015; Mustapha, 2008; Schwartz and Jenkins, 2000). As aquatic ecosystems provide valuable water and forage sources in semi-arid regions, it is important to understand their structure and functioning for management and conservation purposes. They are major contributors to regional biodiversity (Williams, 2005)

Objectives

Methods

Results