Annual benthic data analysis from 2008 to 2015
An extensive programme of sampling has taken place in the Stour and Orwell estuaries since 1997 for Harwich Haven Authority to monitor macrobenthic communities and biotopes. This forms part of the compensation, mitigation and monitoring agreement under the 1998-2000 Capital Dredge Licence to investigate any impacts dredging may have on the benthic environment.
What we did
- Thomson Unicomarine has undertaken all surveys carried out since 1997 (1997, 2003, 2008-2015). We have analysed all samples taken, identified the benthic organisms present and have carried out particle size analysis (PSA) on the sediment samples.
- Every year we have produced a report to summarise the findings of that year’s survey, and every 4 years we have produced a report that detects and analyses any trends in community and biotope changes over the previous four years.
- In the most recent report, univariate statistics were calculated using the data from 1997 to 2015 and multivariate statistics were calculated for 2012 to 2015.
- Each year Thomson presents the findings of the reports to Harwich Haven and the members of their Environmental Steering Group.
Results showed that over the years there had been a change in biotopes throughout both estuaries. Intertidal biotopes are more stable than subtidal biotopes.
Results also indicated that there had been no significant change in species composition between the years.
These reports allow Harwich Haven Authority to monitor effectively the health of the ecosystems within the Stour and Orwell estuaries and therefore respond quickly to any significant changes. This work also allows conservation groups to monitor the presence of prey items for birds present in the adjacent Special Protected Areas (SPAs).