- On 11th July 2017
- In Dredging, Sediment Management
- By William Coulet
Whilst beneficially using dredged sediment to restore habitats is not a new concept, much of the work that has been conducted and monitored is relatively new, especially when compared against the temporal scales sometimes required for those habitats to fully recover their ecological functioning to resemble wholly natural systems.
It is therefore essential to monitor the environmental impact of these types of projects now, to allow future works to be fully informed and permit accurate impact assessment. Consequently, monitoring the impacts of the Brightlingsea Harbour Commissioners Dredging and Restoration works is a cornerstone of the project and a rare opportunity to address gaps in our understanding or lend quantitative support to anecdotal evidence.
Joining in with the 4th July festivities and history going on across the pond, Exo Environmental ‘liberated’ sediment samples from within the Year 1 dredging areas across Brightlingsea Creek and the wider Colne Estuary. Not only did this give the Exo Surveyor her first chance to flex her davit (see our blog!), it also provided samples for the analysis of benthic fauna community composition and particle size distribution and how this has changed 4 months on from the cessation of dredging works. Benthic sampling was conducted with a day-grab at various sampling stations throughout the harbour.
As tidal estuaries are considered relatively extreme environments, the benthic fauna that typically inhabit these areas are considered resilient to disturbance events. As a result, “recovery of mud by worms” has previously just been simply assumed to happen… The dataset being compiled by the Brightlingsea Harbour Commissioners over the course of the project, will therefore provide additional scientific site specific data to prove, or disprove, this theory whilst also supporting others within the industry in quantifying likely recovery times of dredging sites by local benthic fauna and how changes in particle size distribution (in this case, the removal of accumulated fines) affect the biological community composition.
This is an important consideration for the future of dredging works as we as a society endeavour to reduce our environmental impact. If you have any questions regarding the matter or need help with dredging licence applications and feel we may be able to help, please get in touch!