Environmental drivers of aquatic macrophyte communities in southern tropical African rivers: Zambia as a case study

Michael P. Kennedy, Pauline Lang, Julissa Tapia Grimaldo, Sara Varandas Martins, Alannah Bruce, Adam Hastie, Steven Lowe, Magdi M. Ali, Henry Sichingabula, Helen Dallas, John Briggs, Kevin J. Murphy

    Research output: Contribution to journalArticle

    19 Citations (Scopus)
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    Abstract

    The first-ever extensive macrophyte survey of Zambian rivers and associated floodplain waterbodies, conducted during 2006–2012, collected 271 samples from 228 sites, mainly located in five freshwater ecoregions of the world primarily represented in Zambia. The results supported the hypothesis that variation in macrophyte community structure (measured as species composition and diversity) in southern tropical African river systems, using Zambia as a case study area, is driven primarily by geographical variation in water physico-chemical conditions. In total, 335 macrophyte taxa were recorded, and a chronological cumulative species records curve for the dataset showed no sign of asymptoting: clearly many additional macrophyte species remain to be found in Zambian rivers. Emergent macrophytes were predominant (236 taxa), together with 26 floating and 73 submerged taxa. Several species were rare in a regional or international context, including two IUCN Red Data List species: Aponogeton rehmanii and Nymphaea divaricata. Ordination and classification analysis of the data found little evidence for temporal change in vegetation, at repeatedly-sampled sites, but strong evidence for the existence of seven groups of samples from geographically-varied study sites. These supported differing sets of vegetation (with eight species assemblages present in the sample-groups) and showed substantial inter-group differences in both macrophyte alpha-diversity, and geographically-varying physico-chemical parameters. The evidence suggested that the main environmental drivers of macrophyte community composition and diversity were altitude, stream order, shade, pH, alkalinity, NO3-N, and underwater light availability, while PO4-P showed slightly lower, but still significant variation between sample-groups.

    Original languageEnglish
    Pages (from-to)19-28
    Number of pages9
    JournalAquatic Botany
    Volume124
    DOIs
    Publication statusPublished - Jul 2015

    Bibliographical note

    NOTICE: this is the author’s version of a work that was accepted for publication in Aquatic Botany. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Aquatic Botany, [124, (2015)] DOI: 10.1016/j.aquabot.2015.03.002

    © 2015, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/

    Funder

    European Commission/African, Caribbean and Pacific Group of States (EC/ACP) Science & Technology Programme

    Keywords

    • River plants
    • Africa
    • Macrophyte diversity
    • Tropical river ecology

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