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

Water SA ◽  
2018 ◽  
Vol 44 (2 April) ◽  
Author(s):  
Stembile Msiteli-Shumba ◽  
Shakki Kativu ◽  
Beaven Utete ◽  
Edwin Makuwe ◽  
Florence D Hulot
Keyword(s):  
Land Use ◽  
Water Level ◽  
Aquatic Ecosystems ◽  
National Park ◽  
Water Hardness ◽  
Dry Season ◽  
Driving Factors ◽  
Water Level Fluctuations ◽  
Arid Environments ◽  
Hwange National Park

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.

scholarly journals Seasonal Water Level Fluctuation and Concomitant Change of Nutrients Shift Microeukaryotic Communities in a Shallow Lake

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2317
Author(s):  
Yang Liu ◽  
Ze Ren ◽  
Xiaodong Qu ◽  
Min Zhang ◽  
Yang Yu ◽  
...  
Keyword(s):  
Water Level ◽  
Soluble Reactive Phosphorus ◽  
Dry Season ◽  
Water Level Fluctuation ◽  
Water Level Fluctuations ◽  
Rrna Gene ◽  
Level Fluctuation ◽  
Wet Season ◽  
Concomitant Change ◽  
Modular Structures

Seasonal water level fluctuations (WLFs) impose dramatic influences on lake ecosystems. The influences of WLFs have been well studied for many lake biotas but the microeukaryotic community remains one of the least-explored features. This study employed high-throughput 18S rRNA gene sequencing to investigate the spatiotemporal patterns of microeukaryotic communities in the dry and wet seasons with concomitant change of nutrients in Poyang Lake, which experiences huge seasonal WLFs. The results showed that the dry season and wet season had distinct microeukaryotic community compositions and structures. In the dry season, Ciliophora (13.86–40.98%) and Cryptomonas (3.69–18.64%) were the dominant taxa, and the relative abundance of these taxa were significant higher in the dry season than wet season. Ochrophyta (6.88–45.67%) and Chlorophyta (6.31–22.10%) was the dominant taxa of microeukaryotic communities in the wet season. The seasonal variation of microeukaryotic communities was strongly correlated to seasonal nutrient variations. Microeukaryotic communities responded significantly to dissolved organic carbon, total nitrogen, nitrate, and soluble reactive phosphorus in the dry season, and correlated to nitrate and total phosphorus in the wet season. The microeukaryotic community showed different modular structures in two seasons, and nutrient variations were the key factors influencing seasonal variations of the modular structures. Moreover, microeukaryotic community networks based on different seasons indicated that the microeukaryotic community co-occurrence patterns were not constant but varied largely associating with the nitrogen and phosphorus variations under the effects of WLFs. Our results are important for understanding how microeukaryotic communities respond to nutrient variation under seasonal water level fluctuation.

scholarly journals Spotted hyaenas Crocuta crocuta prey on new-born elephant calves in Hwange National Park, Zimbabwe

Koedoe ◽  
2001 ◽  
Vol 44 (2) ◽  
Author(s):  
Julia Salnicki ◽  
Marion Teichmann ◽  
V.J. Wilson ◽  
F. Murindagomo
Keyword(s):  
National Park ◽  
Prey Species ◽  
Loxodonta Africana ◽  
Dry Season ◽  
Crocuta Crocuta ◽  
Giraffa Camelopardalis ◽  
New Born ◽  
Varied Diet ◽  
Conducting Research ◽  
Hwange National Park

Spotted hyaena Crocuta crocuta are known to be opportunists and to have a varied diet including mammals, reptiles and birds. Prey most often hunted are medium sized ungulates but spotted hyaenas will on occasion take larger species such as giraffe Giraffa camelopardalis and zebra Equus burchellii. They are also known to hunt whichever species are most abundant and will vary their prey seasonally. In this study spotted hyaenas were observed to take an unusual prey species in the form of elephant calves (Loxodonta africana). On a number of occasions hyaenas were observed feeding on or killing newborn and very young elephant calves. These observations were made whilst the authors were conducting research on spotted hyaena ecology in the woodlands of Hwange National Park, Zimbabwe and were made during the dry season between September and November 1999.

scholarly journals Temperature as a constraint on the timing and duration of African elephant foraging trips

2020 ◽  
Author(s):  
David Rozen-Rechels ◽  
Hugo Valls-Fox ◽  
Cheryl Tinashe Mabika ◽  
Simon Chamaillé-Jammes
Keyword(s):  
Dry Season ◽  
Sweat Glands ◽  
Arid Environments ◽  
African Elephants ◽  
Large Herbivores ◽  
Daily Movement ◽  
Thermal Constraints ◽  
Terrestrial Animal ◽  
Hwange National Park ◽  
Hot Environments

Abstract In arid and semiarid environments, water is a key resource that is limited in availability. During the dry season, perennial water sources such as water pans often are far apart and shape the daily movement routines of large herbivores. In hot environments, endotherms face a lethal risk of overheating that can be buffered by evaporative cooling. Behavioral adjustments are an alternative way to reduce thermal constraints on the organism. The trade-off between foraging and reaching water pans has been studied widely in arid environments; however, few studies have looked into how ambient temperature shapes individual trips between two visits to water. In this study, we tracked during the dry season the movement of eight GPS-collared African elephants (Loxodonta africana) cows from different herds in Hwange National Park, Zimbabwe. This species, the largest extant terrestrial animal, is particularly sensitive to heat due to its body size and the absence of sweat glands. We show that most foraging trips depart from water at nightfall, lowering the average temperature experienced during walking. This pattern is conserved across isolated elephant populations in African savannas. We also observed that higher temperatures at the beginning of the trip lead to shorter trips. We conclude that elephants adjust the timing of foraging trips to reduce the thermal constraints, arguing that further considerations of the thermal landscape of endotherms are important to understand their ecology.

scholarly journals Detection and Attribution of Lake Victoria’s Water-Level Fluctuations in a Changing Climate

2021 ◽  
Author(s):  
Obed M. Ogega ◽  
James Mbugua ◽  
Herbert O. Misiani ◽  
Maurice Nyadawa ◽  
Enrico Scoccimarro ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Water Level ◽  
Lake Victoria ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Return Periods ◽  
Model Intercomparison ◽  
Changing Climate ◽  
Intercomparison Project

This study investigated the influence of land-use and precipitation change and variability on Lake Victoria’s water-level fluctuations. Extreme precipitation events, corresponding to extreme water-levels, over the lake and its catchment area were identified and their return periods estimated by fitting them into a generalized extreme value (GEV) distribution. Using general circulation models from the 6th phase of the Coupled Model Intercomparison Project (CMIP6)’s Detection & Attribution Model Intercomparison Project (DAMIP), an assessment of the potential contribution of human-induced climate change on the observed precipitation patterns over the study area was done. The greatest precipitation anomalies for the period 1900-2020 were recorded in 1961’s October-December (OND) season and 2019’s June-August (JJA) and OND seasons, corresponding to the period when the highest water-levels were recorded in Lake Victoria. While land-use change in the study domain was observed, extended and unusually heavy June to December 2019 precipitation bore the greatest responsibility for the 2019/2020 high water-levels in Lake Victoria. The OND precipitation event of 2019 was a 1-in-52-year event compared to the 1961’s 1-in-693 years. Differences in return periods at various parts of the lake imply a high spatial climate variability within the lake itself. An analysis of the fraction of attributable risk (FAR) showed natural variability to have a greater influence on the JJA and OND precipitation patterns over Lake Victoria than human-induced climate change. However, variability over the land area of the study domain was mainly driven by human-induced climate change rather than natural variability, implying a unique climate system over Lake Victoria. Findings from the current study enhance the understanding of Lake Victoria’s water budget and motivate for further research to inform effective strategies on the planning and use of Lake Victoria’s water resources in a changing climate.

Temporal dynamics of dry-season water-hole use by large African herbivores in two years of contrasting rainfall in Hwange National Park, Zimbabwe

2011 ◽  
Vol 27 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Marion Valeix
Keyword(s):  
National Park ◽  
Temporal Dynamics ◽  
Dry Season ◽  
Arid Ecosystems ◽  
Annual Rainfall ◽  
Large Herbivore ◽  
Herbivore Species ◽  
Level Of Aggregation ◽  
Hwange National Park ◽  
Semi Arid

Abstract:As the dry season progresses in arid and semi-arid ecosystems, rain-fed surface water sources become depleted, forcing most animals to concentrate in the immediate vicinity of the few remaining permanent sources of drinking water. This study investigates the temporal dynamics of use of water-holes by nine African large-herbivore species in the dry season in the semi-arid savanna of Hwange National Park, Zimbabwe, and particularly how annual rainfall influences this temporal dynamics. Two contrasting years in terms of annual rainfall were compared: 2003 (a drought – 362.6 mm) and 2004 (average rainfall – 695.8 mm). In 2003, water-holes were used far more intensively and the level of aggregation of herbivores at water-holes was significantly higher. The temporal dynamics of water-hole use in the dry season differed between the two years: in 2003, the peak of water-hole use started much earlier and lasted 3 mo. Elephants and grazers showed the largest difference in use of water-holes between 2003 and 2004 supporting the suggestion that browsers are less water dependent. This study suggests that annual rainfall should be taken into account when predicting the peak of the dry season.

scholarly journals Water level fluctuations in selected Wielkopolski National Park lakes in 2012 against changes noted in 2007-2008

2013 ◽  
Vol 13 (3) ◽  
pp. 147-153
Author(s):  
Michał Lorenc ◽  
Renata Dondajewska ◽  
Lech Kaczmarek
Keyword(s):  
Water Level ◽  
National Park ◽  
Early Spring ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Winter Period ◽  
New Information ◽  
Wielkopolski National Park ◽  
Flow Through ◽  
Water Stage

AbstractThe results presented in this paper of water level fluctuations in selected lakes of Wielkopolski National Park have a preliminary character, contributing new information to the knowledge on this area. Five lakes situated in three distinct tunnel valleys were selected for research: Jarosławieckie, Góreckie, Budzyńskie, Witobelskie and Łódzko-Dymaczewskie. The water level was measured from December 2006 till January 2008 and from January till December of 2012 with ca. monthly frequency. An increase in the water stage was noted in the autumn-winter period, which was rather unusual. The comparison of years 2007 and 2012 indicated higher water levels in the latter. The amplitude of the water level was higher in flow-through lakes due to the reaction to precipitation in early spring as well as different catchment features. Specific water level fluctuations in Lake Góreckie are probably related to the influence of groundwater of the Wielkopolska fossil valley.

scholarly journals Zebra diel migrations reduce encounter risk with lions over selection for safe habitats

2017 ◽  
Author(s):  
Nicolas Courbin ◽  
Andrew J. Loveridge ◽  
Hervé Fritz ◽  
David W. Macdonald ◽  
Rémi Patin ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
National Park ◽  
Vegetation Types ◽  
Night Time ◽  
Trade Off ◽  
Terrestrial System ◽  
Selection For ◽  
Hwange National Park ◽  
Time Selection ◽  
Behavioural Strategies

AbstractDiel migrations (DMs) undertaken by prey to avoid visual predators during the day have been demonstrated in many taxa in aquatic ecosystems. We reveal that zebras in Hwange National Park (Zimbabwe) employ a similar anti-predator strategy. Zebras forage near waterholes during the day but move away from them at sunset. We demonstrate that this DM, occurring over a few km, dramatically reduces their night-time risk of encountering lions, which generally remain close to waterholes. By contrast, zebra changes in night-time selection for vegetation types marginally reduced their risk of encountering lions. This may arise from a trade-off between encounter risk and vulnerability across vegetation types, with zebras favouring low vulnerability once DM has reduced encounter risk. In summary, here we (1) quantify the effect of a predator-induced DM in a terrestrial system on the likelihood of encountering a predator, (2) distinguish the effects of the DM from those related to day/night changes in selection for vegetation types. We discuss how revealing how prey partition their risk between predator encounter risk and habitat-driven vulnerability is likely critical to understand the emergence of anti-predator behavioural strategies.

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