The influence of a semi-arid sub-catchment on suspended sediments in the Mara River, Kenya

Dutton, Christopher L.; Subalusky, Amanda L.; Anisfeld, Shimon C.; Njoroge, Laban; Post, David M.

doi:10.1371/journal.pone.0192828

Cited by 40 publications

(41 citation statements)

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“…The lower proportion of flux accounted for by estimates of wildlife inputs at the Hippo + WB site may be due to the influence of the Talek River sub‐catchment, which contains high densities of livestock and a growing human population and contributes around 50% of the suspended sediments downstream (Dutton et al. , ). At the Hippo + WB site when carcasses were present, our estimate of C inputs from wildebeest was 93% of daily net DOC flux.…”

Section: Discussionmentioning

confidence: 99%

“…These differences also highlight the potentially important role of other wildlife and human activities on the landscape, particularly in the Talek River sub‐catchment (Dutton et al. , ).…”

Section: Discussionmentioning

confidence: 99%

“…A more detailed description of our discharge measurements and rating curves is in Dutton et al. (). The Mara River is characterized by a bimodal hydrological cycle, with long rains from March to June and short rains from October to December.…”

Section: Methodsmentioning

confidence: 99%

“…Base flow discharge at the Hippo + WB site was lower on average than at the No Wildlife site, although the Hippo + WB site had larger and more frequent high discharge events associated with rain, likely due to large rain events in the Talek River sub‐catchment (Dutton et al. ). Mean discharge at the No Wildlife site over the course of our study was 15.6 m 3 /s, and it ranged from 0.8 to 116.3 m 3 /s.…”

Section: Methodsmentioning

confidence: 99%

“…Hippo inputs also have finer particulates that increase turbidity in the river (Dutton et al. , ), which may reduce light penetration and limit primary production, thus influencing the physical characteristics of the recipient ecosystem. Hippo inputs occur in the river throughout the year, although their magnitude can vary seasonally as a function of resource quality and time spent grazing outside the river (Eltringham , Kanga et al.…”

Section: Introductionmentioning

confidence: 99%

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Organic matter and nutrient inputs from large wildlife influence ecosystem function in the Mara River, Africa

Subalusky

Dutton

Njoroge

et al. 2018

Ecology

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Animals can be important vectors for the movement of resources across ecosystem boundaries. Animals add resources to ecosystems primarily through egestion, excretion, and carcasses, and the stoichiometry and bioavailability of these inputs likely interact with characteristics of the recipient ecosystem to determine their effects on ecosystem function. We studied the influence of hippopotamus excretion/egestion and wildebeest carcasses, and their interactions with discharge, in the Mara River, Kenya. We measured nutrient dissolution and decomposition rates of wildlife inputs, the influence of inputs on nutrient concentrations and nutrient limitation in the river and the influence of inputs on biofilm growth and function in both experimental streams and along a gradient of inputs in the river. We found that hippopotamus excretion/egestion increases ammonium and coarse particulate organic matter in the river, and wildebeest carcasses increase ammonium, soluble reactive phosphorus, and total phosphorus. Concentrations of dissolved carbon and nutrients in the water column increased along a gradient of wildlife inputs and during low discharge, although concentrations of particulate carbon decreased during low discharge due to deposition on the river bottom. Autotrophs were nitrogen limited and heterotrophs were carbon limited and nitrogen and phosphorus colimited upstream of animal inputs but there was no nutrient limitation downstream of inputs. In experimental streams, hippo and wildebeest inputs together increased biofilm gross primary production (GPP) and respiration (R). These results differed in the river, where low concentrations of hippo inputs increased gross primary production (GPP) and respiration (R) of biofilms, but high concentrations of hippo inputs in conjunction with wildebeest inputs decreased GPP. Our research shows that inputs from large wildlife alleviate nutrient limitation and stimulate ecosystem metabolism in the Mara River and that the extent to which these inputs subsidize the ecosystem is mediated by the quantity and quality of inputs and discharge of the river ecosystem. Thus, animal inputs provide an important ecological subsidy to this river, and animal inputs were likely important in many other rivers prior to the widespread extirpation of large wildlife.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Organic matter and nutrient inputs from large wildlife influence ecosystem function in the Mara River, Africa

Subalusky

Dutton

Njoroge

et al. 2018

Ecology

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Late Pleistocene and Holocene Afromontane vegetation and headwater wetland dynamics within the Eastern Mau Forest, Kenya

Githumbi

Mustaphi

Marchant

2021

J Quaternary Science

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The Mau Forest Complex is Kenya's largest fragment of Afromontane forest, providing critical ecosystem services, and has been subject to intense land use changes since colonial times. It forms the upper catchment of rivers that drain into major drainage networks, thus supporting the livelihoods of millions of Kenyans and providing important wildlife areas. We present the results of a sedimentological and palynological analysis of a Late Pleistocene-Holocene sediment record of Afromontane forest change from Nyabuiyabui wetland in the Eastern Mau Forest, a highland region that has received limited geological characterization and palaeoecological study. Sedimentology, pollen, charcoal, X-ray fluorescence and radiocarbon data record environmental and ecosystem change over the last~16 000 cal a BP. The pollen record suggests Afromontane forests characterized the end of the Late Pleistocene to the Holocene with dominant taxa changing from Apodytes, Celtis, Dracaena, Hagenia and Podocarpus to Cordia, Croton, Ficus, Juniperus and Olea. The Late Holocene is characterized by a more open Afromontane forest with increased grass and herbaceous cover. Continuous Poaceae, Cyperaceae and Juncaceae vegetation currently cover the wetland and the water level has been decreasing over the recent past. Intensive agroforestry since the 1920s has reduced Afromontane forest cover as introduced taxa have increased (Pinus, Cupressus and Eucalyptus).

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Water security in sub‐Saharan Africa: Understanding the status of sustainable development goal 6

et al. 2021

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The world is nearing the 2030 target‐year by which sustainable development goals (SDGs) should be achieved. While other developing regions seem to be making progress toward achieving SDG6, sub‐Saharan Africa (SSA) is lagging behind significantly, particularly with regard to access to water supply and sanitation (WSS). As a result, most studies evaluating progress toward the achievement of water security SDGs in SSA have focused on WSS while the rest of the SDG6 targets have received scant attention, often using fragmented or incomplete evidence. Here, we fill this knowledge gap by conducting a comprehensive assessment of the status of SDG6 in all 48 countries in SSA. We provide a review of the progress made, the challenges affecting each SDG6 target and examine the different political, socioeconomic, and environmental factors with potential to undermine the achievement of SDG6 in the region. Our review clearly demonstrates that it is likely that most countries may not achieve water security by 2030. The complex nature of the challenges and factors impeding the achievement of water security in SSA outlined here suggests that a holistic intervention involving local, national, and international stakeholders and the research community is urgently needed to address SDG6 if the 2030 target date is to be met. Approaches to enhance water security may equally consider: (a) underpinning peace and security in SSA and (b) the commitment of more financial resources by donors particularly during this period of COVID‐19 pandemic. This article is categorized under: Human Water Human Water > Water Governance Engineering Water > Planning Water

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The influence of a semi-arid sub-catchment on suspended sediments in the Mara River, Kenya

Cited by 40 publications

References 45 publications

Organic matter and nutrient inputs from large wildlife influence ecosystem function in the Mara River, Africa

Organic matter and nutrient inputs from large wildlife influence ecosystem function in the Mara River, Africa

Late Pleistocene and Holocene Afromontane vegetation and headwater wetland dynamics within the Eastern Mau Forest, Kenya

Water security in sub‐Saharan Africa: Understanding the status of sustainable development goal 6

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