Freshwater habitats are home to a significant portion of the world's biodiversity, housing more than 10% of all known animals and about 50% of all known fish species. Despite the critical role water plays for both people and nature, it is a surprisingly finite resource that faces numerous threats. Climate change, population growth, and changing consumption patterns are among the many forces that increasingly put freshwater systems at risk.
In semi-arid ecosystems, herbivore distribution is generally more homogeneous in the wet season when surface water is abundant, than in the dry season when only permanent sources remain. Water dependence varies between herbivore species, but most need to access drinking water on a few-day basis at the peak of the dry season.
Water-dependent wildlife populations in sensitive African dryland regions need continued access to limited surface water resources - even as human development increases in these areas. Restricting access and concentrating wildlife populations along riparian regions can impact water quality and, potentially, human health.
WWF partners with governments, businesses, financial institutions and communities to ensure healthy freshwater systems exist to provide a sustainable future for all. In 2017, WWF and partners petitioned government to declare the Luangwa River as a Water Resource Protection Area and protect it from threats such as a proposed dam, unsustainable agriculture and deforestation. Close to 200,000 people worldwide signed the petition. WWF has been conducting ongoing research with partners such as the Water Resources Management Authority and ABInBev on the water situational analysis of the Lower Kafue River Basin.
The Interplay Between Wildlife, Water Quality, and Human Health
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Loss of habitat and limitation of wildlife access to rivers and floodplains in water-restricted regions may increase the impact of species on surface water resources. Maintaining sufficient access for water-dependent wildlife along riparian areas in dryland regions may not only be part of a sustainable conservation strategy, but may also be important for securing clean water and improved human health.
A study conducted in the dryland Chobe River system in Northern Botswana, the only permanent surface water for humans and animals in the region, evaluated water quality dynamics over a three-year period. The study area also included two towns and mixed-use land area where a limited number of subsistence farming enterprises are located. Patterns of water quality decline were compared to animal densities, both domestic and wildlife species, fecal counts along the riparian zone, and land characteristics.
Significant relationships were found in the dry season between increased concentrations of Escherichia coli (a common bacteria from the gut of humans and animals), flood plain habitat, protected land use, and fecal counts from elephants and other wildlife along the banks of the river. Dry-season terrestrial fecal densities were also important predictors of E. coli concentrations in the following wet season, underscoring the longer term influence of terrestrial fecal loads.
In contrast to the dry season, wet season E. coli was only associated with suspended solid matter in the water, suggesting storm water and sediment runoff may significantly influence E. coli loads during that season.
One-health approaches that include consideration of the environment are necessary to understand the complex dynamics that link humans, animals, and the environment to resultant health outcomes.
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Surface water quality declines are typically associated with human habitation and landscape change, such as agriculture, livestock husbandry, industry, and urban development. But in areas where wildlife populations concentrate at high densities along perennial dryland systems such as the Chobe River, this influence may extend beyond the terrestrial environment to impact seasonal water quality dynamics.
Activities of elephants and other large animals play an essential role in maintaining the long-term integrity of river corridors in southern Africa, adding nutrients and increasing patch heterogeneity of the riparian landscape.
While human landscape modifications and pollution are most often associated with water quality declines, this work highlights the potential impact of wildlife on surface water resources when access is limited.
Competition Between Lions and Their Prey
Large carnivores inhabiting ecosystems with heterogeneously distributed environmental resources with strong seasonal variations frequently employ opportunistic foraging strategies, often typified by seasonal switches in diet.
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A study was conducted between 2005 and 2007 in the northern sector of Hwange National Park (Hwange), north-western Zimbabwe, latitudes 18°30′ and 19°50′ S and longitudes 25°45′ and 27°30 E. The study area covers c. 7554 km2 of dystrophic woodland savanna. Approximately 98% of the annual rainfall occurs from October to April and the long-term annual average (calculated for the period 1918-2007) is 632 mm (range: 324-1160 mm). Annual rainfall was 330 mm in 2004-2005, 683 mm in 2005-2006 and 703 mm in 2006-2007. There is no perennial water in Hwange, and rain fed pans hold water throughout the year only in high rainfall years. Water is artificially supplied to some waterholes during the dry season (∼40 in the study area).
The vulnerability to predation is further influenced by the interaction between vegetation cover, hunting strategy of the predator and anti-predatory strategy of the prey.
The study assessed lion diet by combining carcass observations and faeces collection from GPS clusters, a method with recognized strengths. It investigated whether there is a seasonal shift of prey preference (use vs. availability) suggestive of different foraging strategies in different seasons.
Lion waiting in Namibia
Key Findings on Lion Diet and Prey Selection
- Buffalo consistently emerged as the most frequently utilised prey in all seasons by both male (56%) and female (33%) lions, contributing the most to lion dietary biomass.
- Jacobs’ index also revealed that buffalo was the most intensively selected species throughout the year.
- For female lions, kudu and to a lesser extent the group “medium Bovidae” are the most important secondary prey.
- Browsers, such as giraffe and kudu, mainly consumed in the early dry season, and grazers, such as zebra and suids, contributing more to female diet in the late dry season.
- Jacobs’ index finally revealed a very strong preference for kills within 2 km from a waterhole for all prey species, except small antelopes, in all seasons.
Seasonal Variations in Lion Prey
Seasonal variation in relative contribution to lion kills by different prey species are shown in Fig. 1. Buffalo (the highest contribution in all seasons for both sexes) showed a constant contribution to male diet throughout the seasons, and a lower contribution to female diet in the early dry season. Proportions of each age class were relatively constant with an increase in the predation on juveniles by males in the wet season. Zebra and Suidae showed a peak in contribution to female lion diet in the late dry season. Browsers such as giraffe, kudu and small antelopes were mainly consumed in the early dry season. Medium Bovidae contributed least in the late dry season. 62% of elephants were taken in 2005, which was a drought year (rainfall: 330 mm), concurring with increasing relative contribution of elephant to lion kills in the late dry season and peak contribution in the wet season (due to many kills in November before the first rains). Juveniles were taken almost exclusively.
Dietary Diversity Revealed Through Faecal Analysis
Faecal analysis revealed a higher number of species occurring in the lion diet (20 species), owing to the detection of more small prey items, unexpectedly including climbing mice (Dendromus spp.) and common mice (Mus spp.). The frequency of occurrence of species in the faecal dataset was highest for kudu (24%) followed by buffalo and medium Bovidae (each representing 18%; the medium Bovidae class is dominated by sable and eland for faecal data), small antelopes (17%), and giraffe (7%) collectively contributing 84% of the species found in faecal samples.
Once biomass consumption was estimated, buffalo contributed the most to lion dietary intake (33%), followed by giraffe (20%), medium Bovidae (18%), and kudu (14%) and collectively accounting for 85% of the prey biomass consumed. Small antelopes contributed 1% to lion diet by relative biomass consumed.
Lions Eating Zebra Carcass
The Lions Rule | Hunting Giants
Water Scarcity and Community Initiatives
Pamela Chisanga of WaterAid Zambia said contamination of water is as big a problem as lack of it in parts of Zambia. The Red Cross has provided 28 boreholes in Limulunga district in Western province.
The Broader Context of Competition
Animals of different species typically compete with each other only for food, water and shelter. But they often compete with members of their own species for mates and territory as well.
| Indicator | Value |
|---|---|
| TARWR Volume | 286 km3/year (286 billion m3/year) |
| Per Capita | 17,520 m3/year |
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