Direct observations of the effect of fine sediment deposition on the vertical movement of Gammarus pulex (Amphipoda: Gammaridae) during substratum drying

Atish N Vadher, Jonathan Millett, Paul J Wood

Research output: Contribution to JournalArticle

Abstract

Benthic macroinvertebrates inhabit the streambed sediments of temporary streams during drying events. Fine sediment (< 2 mm in diameter) deposition and clogging of interstitial pathways reduces the connectivity between benthic and subsurface habitats, potentially inhibiting macroinvertebrate vertical movements. Direct observations within subsurface sediments are, however, inherently difficult. As a result, confirmation of macroinvertebrate vertical movement, and the effect of fine sediment, is limited. We used laboratory mesocosms containing transparent gravel sized particles (10–15 mm) to facilitate the direct observation and tracking of vertical movements by Gammarus pulex in response to water level reduction and sedimentation. Seven sediment treatments comprised two fine sediment fractions (small: 0.125–0.5 mm, coarse sand: 0.5–1 mm) deposited onto the surface of the substrate, and a control treatment where no fine sediment was applied. We found that G. pulex moved into the subsurface gravel sediments in response to drying, but their ability to remain submerged during water level reduction was impeded by fine sediment deposition. In particular deposition of the coarser sand fraction clogged the sediment surface, limiting vertical movements. Our results highlight the potential effect of sedimentation on G. pulex resistance to drying events in streams.
Original languageEnglish
Pages (from-to)73-82
Number of pages10
JournalHydrobiologia
Volume815
Issue number1
Early online date26 Feb 2018
DOIs
Publication statusPublished - 1 Jun 2018

Keywords

  • Burrowing
  • Hyporheic zone
  • Intermittent rivers
  • Invertebrate
  • Mesocosm
  • Sedimentation

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