This report presents the outcomes from a Phase I and Phase II intertidal survey of the Duddon Estuary Site of Special Scientific Interest (SSSI). The Duddon Estuary is a component of the Morecambe Bay Special Area of Conservation (SAC). The work was commissioned by Natural England and undertaken by specialist contractors ABPmer.
The survey provides a description of the sedimentary intertidal habitat on the Duddon Estuary and an indicative assessment of its ecological condition. Eight biotopes were recorded across the site and an extent for each is provided. A qualitative assessment of temporal change suggested a marginal shift in sediment composition from occasional finer muddier sand sediments to medium sand from 2004-2005 to 2023. The sediments support an invertebrate community characteristic of moderately exposed inner to middle estuary, variable salinity conditions. All stations sampled were assessed to have either good or high IQI status.
Anthropogenic activities recorded included vehicular access, evidence of fishing and bait digging, abandoned vehicles and vessels, and litter. The survey noted limited evidence of disturbance to the feature from these activities.
This report provides evidence to inform Natural England’s condition assessment for the SSSI feature ‘Littoral sediment’ and the SAC feature ‘Mudflats and Sandflats not covered by seawater at low tide’. It also creates baseline data to use for long-term site monitoring. Natural England have provided comments on the limitations of the survey and recommendations for these future studies.