Fish activity: A major mechanism for sediment resuspension and organic matter remineralization in coastal marine sediments

Gitai Yahel, Ruthy Yahel, Timor Katz, Boaz Lazar, Barak Herut, Verena Tunnicliffe

Research output: Contribution to journalArticlepeer-review


We quantify sediment resuspension due to groundfish activity in a partly anoxic basin using acoustic backscatter sensors, transmissometers, and remotely operated cameras on stationary and mobile platforms. Where these fish were present, a distinct benthic nepheloid layer (BNL) developed despite minimal bottom currents (<10 cm s-1). In contrast, water clarity was markedly higher over the adjacent anoxic and fishless zone. Sediment resuspension events, mostly by flatfish, occurred at a rate of >100 disturbances m-2 d-1 resulting in complete surface reworking every 2.5 d and a daily resuspension of 1.3 ± 0.7 l bulk sediment m-2 d-1. Preliminary geochemical measurements suggest substantial impact of fish resuspension activity, the immediate effect being an instantaneous increase in nutrient concentration in the benthic boundary layer and a drop in oxygen concentration. Over longer time scales (hours to days), the freshly exposed organic matter is oxidized and additional nutrients (silica, ammonium, phosphate) are regenerated and released to the water. The increase in benthic oxygen demand suggests that fish activity reduces organic carbon sequestration by 9 ± 5 mmol C m-2 d -1, equivalent to ∼40% of its downward flux in this basin. To date, these processes are missing from geochemical models and require further investigation, particularly considering the depletion of groundfish stocks and the likely effects on global biogeochemical cycles.

Original languageEnglish
Pages (from-to)195-209
Number of pages15
JournalMarine Ecology - Progress Series
StatePublished - 9 Dec 2008
Externally publishedYes


  • Benthic-pelagic coupling
  • Bioturbation
  • Carbon sequestration
  • Flatfish
  • Saanich inlet
  • Sediment geochemistry

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology


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