Dredging-induced turbid plumes affect bio-irrigation and biogeochemistry in sediments inhabited by Lanice conchilega (Pallas, 1766)

Sebastiaan Mestdagh*, Tom Ysebaert, Tom Moens, Carl Van Colen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)

Abstract

Building man-made structures in coastal seas are often preceded by dredging operations, inducing turbid plumes of suspended sediment. To study the effects of such high-concentration sediment plumes on the suspension-feeding polychaete Lanice conchilega, a laboratory experiment was performed, in which individuals of L. conchilega were exposed to natural seawater with a suspended sediment concentration (SSC) of ?0.3 g l-1 and treatments with elevated SSC of 5 and 1 g l-1, representing concentrations in a dredging plume at the moment of sediment release and after initial dilution, respectively. We measured clearance rates of sediment particles, biogeochemical fluxes, and bio-irrigation. While clearance rates and nitrite efflux significantly increased in both treatments with elevated SSC compared with the control, bio-irrigation increased at 1 g l-1 but was lowest at 5 g l-1. It is suggested that piston pumping is intensified under intermediate concentrations to remove sediment, but ceases under high concentrations are due to sediment ingestion. By transporting oxygen into the sediment, bio-irrigation enhances aerobic microbial processes, among which nitrification. We conclude that short-Term extreme suspended sediment concentrations can have a significant impact on the biogeochemistry of the seabed through changes in behaviour of L. conchilega.

Original languageEnglish
Pages (from-to)1219-1226
Number of pages8
JournalICES Journal of Marine Science
Volume77
Issue number3
DOIs
Publication statusPublished - May 2020

Keywords

  • bio-irrigation
  • biogeochemistry
  • dredging
  • Lanice conchilega
  • SSC
  • suspension feeding

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