Sediment deposition from eroding peatlands alters headwater invertebrate biodiversity

Lee Brown, Katie L. Aspray, Mark E. Ledger, Chris Mainstone, Sheila M. Palmer, Martin Wilkes, Joesph Holden

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2 Citations (Scopus)
11 Downloads (Pure)

Abstract

Land use and climate change are driving widespread modifications to the biodiverse and functionally unique headwaters of rivers. In temperate and boreal regions, many headwaters drain peatlands where land management and climate change can cause significant soil erosion and peat deposition in rivers. However, effects of peat deposition in river ecosystems remain poorly understood. We provide two lines of evidence—derived from sediment deposition gradients in experimental mesocosms (0–7.5 g/m 2 ) and headwaters (0.82–9.67 g/m 2 )—for the adverse impact of peat deposition on invertebrate community biodiversity. We found a consistent negative effect of sediment deposition across both the experiment and survey; at the community level, decreases in density (1956 to 56 individuals per m 2 in headwaters; mean 823 ± 129 (SE) to 288 ± 115 individuals per m 2 in mesocosms) and richness (mean 12 ± 1 to 6 ± 2 taxa in mesocosms) were observed. Sedimentation increased beta diversity amongst experimental replicates and headwaters, reflecting increasing stochasticity amongst tolerant groups in sedimented habitats. With increasing sedimentation, the density of the most common species, Leuctra inermis, declined from 290 ± 60 to 70 ± 30 individuals/m 2 on average in mesocosms and >800 individuals/m 2 to 0 in the field survey. Traits analysis of mesocosm assemblages suggested biodiversity loss was driven by decreasing abundance of invertebrates with trait combinations sensitive to sedimentation (longer life cycles, active aquatic dispersal of larvae, fixed aquatic eggs, shredding feeding habit). Functional diversity metrics reinforced the idea of more stochastic community assembly under higher sedimentation rates. While mesocosm assemblages showed some compositional differences to surveyed headwaters, ecological responses were consistent across these spatial scales. Our results suggest short-term, small-scale stressor experiments can inform understanding of “real-world” peatland river ecosystems. As climate change and land-use change are expected to enhance peatland erosion, significant alterations to invertebrate biodiversity can be expected where these eroded soils are deposited in rivers.

Original languageEnglish
Pages (from-to)602-619
Number of pages18
JournalGlobal Change Biology
Volume25
Issue number2
Early online date10 Nov 2018
DOIs
Publication statusPublished - Feb 2019

Bibliographical note

© 2018 The Authors. Global Change Biology Published by John Wiley & Sons Ltd

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Copyright © and Moral Rights are retained by the author(s) and/ or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This item cannot be reproduced or quoted extensively from without first obtaining permission in writing from the copyright holder(s). The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the copyright holders.

Keywords

  • erosion
  • functional diversity
  • headwater
  • macroinvertebrate
  • peat
  • river
  • stream
  • traits

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • Environmental Science(all)

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  • Cite this

    Brown, L., Aspray, K. L., Ledger, M. E., Mainstone, C., Palmer, S. M., Wilkes, M., & Holden, J. (2019). Sediment deposition from eroding peatlands alters headwater invertebrate biodiversity. Global Change Biology, 25(2), 602-619. https://doi.org/10.1111/gcb.14516