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Marine Ecology Progress Series

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Disposal onto a sandy beach of sediments dredged from a navigation channel suppresses abundances of most intertidal invertebrates and increases surf-zone turbidity (insets). Image: Stephen R. Fegley

Manning LM, Peterson CH, Bishop MJ


Dominant macrobenthic populations experience sustained impacts from annual disposal of fine sediments on sandy beaches


Although of finer grain size than ocean beach sediments, spoil removed during maintenance dredging of navigation channels is often deposited on ocean beaches, justified as 'beach nourishment'. Manning and colleagues find that dredge spoils placed on North Carolina beaches rapidly eroded, and within one year failed to augment the sediment volume on the intertidal beach—thus ending any enhanced protection to beachfront property against storm damage. Instead, the dredge spoils, via burial and/or suffocation, modification of granulometry, and induction of turbidity, suppressed densities of intertidal invertebrate prey and modified habitat selection by surf fishes that feed on them. With impacts to sandy beach ecosystems extending beyond one year, the annual disposal of dredge spoils on sandy beaches constitutes a persistent cumulative impact.


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