Effects of the hippopotamus on the chemistry and ecology of a changing watershed

Keenan Stears, Douglas J. McCauley, Jacques C Finlay, James Mpemba, Ian T. Warrington, Benezeth M. Mutayoba, Mary E. Power, Todd E. Dawson, Justin S. Brashares

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Cross-boundary transfers of nutrients can profoundly shape the ecology of recipient systems. The common hippopotamus, Hippopotamus amphibius, is a significant vector of such subsidies from terrestrial to river ecosystems. We compared river pools with high and low densities of H. amphibius to determine how H. amphibius subsidies shape the chemistry and ecology of aquatic communities. Our study watershed, like many in sub-Saharan Africa, has been severely impacted by anthropogenic water abstraction reducing dry-season flow to zero. We conducted observations for multiple years over wet and dry seasons to identify how hydrological variability influences the impacts of H. amphibius. During the wet season, when the river was flowing, we detected no differences in water chemistry and nutrient parameters between pools with high and low densities of H. amphibius. Likewise, the diversity and abundance of fish and aquatic insect communities were indistinguishable. During the dry season, however, high-density H. amphibius pools differed drastically in almost all measured attributes of water chemistry and exhibited depressed fish and insect diversity and fish abundance compared with low-density H. amphibius pools. Scaled up to the entire watershed, we estimate that H. amphibius in this hydrologically altered watershed reduces dry-season fish abundance and indices of gamma-level diversity by 41% and 16%, respectively, but appears to promote aquatic invertebrate diversity. Widespread human-driven shifts in hydrology appear to redefine the role of H. amphibius, altering their influence on ecosystem diversity and functioning in a fashion that may be more severe than presently appreciated.

Original languageEnglish (US)
Pages (from-to)E5028-E5037
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number22
DOIs
StatePublished - May 29 2018

Fingerprint

Artiodactyla
Ecology
Fishes
Rivers
Ecosystem
Insects
Water
Hydrobiology
Hydrology
Food
Africa South of the Sahara
Invertebrates

Keywords

  • Diversity
  • Eutrophication
  • Fish
  • Hydrology
  • Invertebrates
  • Subsidies (9, 10)

Cite this

Effects of the hippopotamus on the chemistry and ecology of a changing watershed. / Stears, Keenan; McCauley, Douglas J.; Finlay, Jacques C; Mpemba, James; Warrington, Ian T.; Mutayoba, Benezeth M.; Power, Mary E.; Dawson, Todd E.; Brashares, Justin S.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 115, No. 22, 29.05.2018, p. E5028-E5037.

Research output: Contribution to journalArticle

Stears, K, McCauley, DJ, Finlay, JC, Mpemba, J, Warrington, IT, Mutayoba, BM, Power, ME, Dawson, TE & Brashares, JS 2018, 'Effects of the hippopotamus on the chemistry and ecology of a changing watershed', Proceedings of the National Academy of Sciences of the United States of America, vol. 115, no. 22, pp. E5028-E5037. https://doi.org/10.1073/pnas.1800407115
Stears, Keenan ; McCauley, Douglas J. ; Finlay, Jacques C ; Mpemba, James ; Warrington, Ian T. ; Mutayoba, Benezeth M. ; Power, Mary E. ; Dawson, Todd E. ; Brashares, Justin S. / Effects of the hippopotamus on the chemistry and ecology of a changing watershed. In: Proceedings of the National Academy of Sciences of the United States of America. 2018 ; Vol. 115, No. 22. pp. E5028-E5037.
@article{9733cf768f244a51a7839bf2cf1374f2,
title = "Effects of the hippopotamus on the chemistry and ecology of a changing watershed",
abstract = "Cross-boundary transfers of nutrients can profoundly shape the ecology of recipient systems. The common hippopotamus, Hippopotamus amphibius, is a significant vector of such subsidies from terrestrial to river ecosystems. We compared river pools with high and low densities of H. amphibius to determine how H. amphibius subsidies shape the chemistry and ecology of aquatic communities. Our study watershed, like many in sub-Saharan Africa, has been severely impacted by anthropogenic water abstraction reducing dry-season flow to zero. We conducted observations for multiple years over wet and dry seasons to identify how hydrological variability influences the impacts of H. amphibius. During the wet season, when the river was flowing, we detected no differences in water chemistry and nutrient parameters between pools with high and low densities of H. amphibius. Likewise, the diversity and abundance of fish and aquatic insect communities were indistinguishable. During the dry season, however, high-density H. amphibius pools differed drastically in almost all measured attributes of water chemistry and exhibited depressed fish and insect diversity and fish abundance compared with low-density H. amphibius pools. Scaled up to the entire watershed, we estimate that H. amphibius in this hydrologically altered watershed reduces dry-season fish abundance and indices of gamma-level diversity by 41{\%} and 16{\%}, respectively, but appears to promote aquatic invertebrate diversity. Widespread human-driven shifts in hydrology appear to redefine the role of H. amphibius, altering their influence on ecosystem diversity and functioning in a fashion that may be more severe than presently appreciated.",
keywords = "Diversity, Eutrophication, Fish, Hydrology, Invertebrates, Subsidies (9, 10)",
author = "Keenan Stears and McCauley, {Douglas J.} and Finlay, {Jacques C} and James Mpemba and Warrington, {Ian T.} and Mutayoba, {Benezeth M.} and Power, {Mary E.} and Dawson, {Todd E.} and Brashares, {Justin S.}",
year = "2018",
month = "5",
day = "29",
doi = "10.1073/pnas.1800407115",
language = "English (US)",
volume = "115",
pages = "E5028--E5037",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "22",

}

TY - JOUR

T1 - Effects of the hippopotamus on the chemistry and ecology of a changing watershed

AU - Stears, Keenan

AU - McCauley, Douglas J.

AU - Finlay, Jacques C

AU - Mpemba, James

AU - Warrington, Ian T.

AU - Mutayoba, Benezeth M.

AU - Power, Mary E.

AU - Dawson, Todd E.

AU - Brashares, Justin S.

PY - 2018/5/29

Y1 - 2018/5/29

N2 - Cross-boundary transfers of nutrients can profoundly shape the ecology of recipient systems. The common hippopotamus, Hippopotamus amphibius, is a significant vector of such subsidies from terrestrial to river ecosystems. We compared river pools with high and low densities of H. amphibius to determine how H. amphibius subsidies shape the chemistry and ecology of aquatic communities. Our study watershed, like many in sub-Saharan Africa, has been severely impacted by anthropogenic water abstraction reducing dry-season flow to zero. We conducted observations for multiple years over wet and dry seasons to identify how hydrological variability influences the impacts of H. amphibius. During the wet season, when the river was flowing, we detected no differences in water chemistry and nutrient parameters between pools with high and low densities of H. amphibius. Likewise, the diversity and abundance of fish and aquatic insect communities were indistinguishable. During the dry season, however, high-density H. amphibius pools differed drastically in almost all measured attributes of water chemistry and exhibited depressed fish and insect diversity and fish abundance compared with low-density H. amphibius pools. Scaled up to the entire watershed, we estimate that H. amphibius in this hydrologically altered watershed reduces dry-season fish abundance and indices of gamma-level diversity by 41% and 16%, respectively, but appears to promote aquatic invertebrate diversity. Widespread human-driven shifts in hydrology appear to redefine the role of H. amphibius, altering their influence on ecosystem diversity and functioning in a fashion that may be more severe than presently appreciated.

AB - Cross-boundary transfers of nutrients can profoundly shape the ecology of recipient systems. The common hippopotamus, Hippopotamus amphibius, is a significant vector of such subsidies from terrestrial to river ecosystems. We compared river pools with high and low densities of H. amphibius to determine how H. amphibius subsidies shape the chemistry and ecology of aquatic communities. Our study watershed, like many in sub-Saharan Africa, has been severely impacted by anthropogenic water abstraction reducing dry-season flow to zero. We conducted observations for multiple years over wet and dry seasons to identify how hydrological variability influences the impacts of H. amphibius. During the wet season, when the river was flowing, we detected no differences in water chemistry and nutrient parameters between pools with high and low densities of H. amphibius. Likewise, the diversity and abundance of fish and aquatic insect communities were indistinguishable. During the dry season, however, high-density H. amphibius pools differed drastically in almost all measured attributes of water chemistry and exhibited depressed fish and insect diversity and fish abundance compared with low-density H. amphibius pools. Scaled up to the entire watershed, we estimate that H. amphibius in this hydrologically altered watershed reduces dry-season fish abundance and indices of gamma-level diversity by 41% and 16%, respectively, but appears to promote aquatic invertebrate diversity. Widespread human-driven shifts in hydrology appear to redefine the role of H. amphibius, altering their influence on ecosystem diversity and functioning in a fashion that may be more severe than presently appreciated.

KW - Diversity

KW - Eutrophication

KW - Fish

KW - Hydrology

KW - Invertebrates

KW - Subsidies (9, 10)

UR - http://www.scopus.com/inward/record.url?scp=85047905282&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85047905282&partnerID=8YFLogxK

U2 - 10.1073/pnas.1800407115

DO - 10.1073/pnas.1800407115

M3 - Article

VL - 115

SP - E5028-E5037

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 22

ER -