Dredging, Islands & Landscaping 2019
IMPROVING WATER QUALITY AND BIODIVERSITY FOR RECREATION AND WILDLIFE
This and other photos courtesy of Mike Millard of the Poole Park Lakes – Public Engagement with Science Facebook Group
The week commencing 14th January 2019 sees us start work on a project with Ebsford Environmental at the Park’s lagoon (boating lake) and two smaller freshwater lakes. We anticipate work will last approximately 15 weeks, ending in April.
The main aim of the project is to:
- increase biodiversity and improve the quality of water, island features and surrounding landscape
- whilst maintaining and improving future use for sailing and other recreational activities.
These improvements follow extensive scientific research & monitoring, funded by the HLF and involving students and specialists from Bournemouth University. The data that has been collected helps us to understand the importance of the lagoon and the potential benefits of the work being undertaken.
- Contractors will dredge areas of sediment lying at the bottom of the lakes and lagoon to increase water depth; the sediment will then be used to create new island habitats and improve existing features.
Various works will follow to significantly improve the quality of the surrounding environment:
- The newly formed islands will either be covered in gravel to encourage birds such as gulls and terns, or planted to encourage other birds that prefer cover.
- A new bird screen and viewing platform will be created close to the railway line, providing a view over the new habitats.
- Gabion baskets, rock boulders (allowing crabs to thrive) and specialist materials will be used to retain dredged sediment and provide a stable lake edge for the islands and around the freshwater lake.
- Experimental floating islands will also be created, providing an alternative feature. Roots of the floating island vegetation will trail in the water, which can help improve water quality as well as providing refuge for fish and other animals.
- We will create a much improved landscape for park users around the freshwater lakes. Behind the gabion baskets we will add new accessible surfacing, large areas of new tree and shrub planting, benches* and picnic tables.
*Please get in touch with Toni Powell if you are interested in having a plaque on the benches and making a donation towards their costs (contact details at the bottom of this page).
Removal of an existing lagoon feature
The ‘island’ feature in front of middle gate car park will be removed as part of these works.
When originally constructed in 2007 this feature was intended to act as a reed bed filter to clean surface water run off that enters the lagoon here from surrounding roads and other hard surfaces. The reed bed has since collected sediment and developed into an island; the high numbers of geese and swans, together with the impounded water, means that water quality in this location can be very poor. Geese and swans will be moved away from the island prior to work starting and in time will find new roosts on other islands.
Impact on park users
Whilst the work takes place there will be some localised disruption to park users. The main area of disruption will be around the freshwater lakes, where some paths will be closed, but access will be maintained to The Ark, the play area and Quiet Garden. Roads through the park will not be affected.
Impact on wildlife
These improvements will create a lot of disturbance across all the water bodies and as a result there will be localised impact on some wildlife.
Whilst many of the larger fish were removed from the lagoon and re-homed late last year, there is the potential for the remaining fish to become stranded and unable to reach wet areas when the lagoon is drained down. However, the process of removing water from the lagoon is quite slow, with numerous low tides required out in the harbour to steadily drop levels in the park; this provides an opportunity for fish to move towards deeper water during the process.
When the lagoon is drained down and the mud and sands are exposed we are likely to see an increase in wildfowl numbers as they find it easier to feed on the insects in the sediments, and on fish in the shallow water. There is little that can be done to practically move any fish out of the lagoon or into deep water.
Due to the presence of the Starlet Sea Anemone – a protected species (see below) – we are required to apply for a licence from Natural England in order to carry out the dredging works.
In the freshwater lake the water level will be reduced slightly to allow construction works to take place, but not to an extent that should be harmful to fish. The northern part of the large freshwater lake, beyond the small bridge, will remain unaffected and act as a refuge for fish. In addition contractors will be installing aerator pumps to oxygenate the water in order to reduce the impact of dredging and the stirring up of sediments.
The Borough of Poole Biodiversity Officer will be monitoring the project and liaising closely with the contractors to ensure works are undertaken in accordance with good practice.
As part of the works we will be asking for volunteer help with planting, fixing, litter picking and more. Please get in touch with Toni Powell to find out more, or sign up to our e-newsletter to be kept informed
Toni Powell, Community Engagement Officer
Telephone: 01202 261700
Life in the water
The lagoon is home to the tiny Starlet Sea Anemone which is a nationally rare species, on the IUCN red list and classified as vulnerable (the same status as the Red Squirrel).
Lagoons are relatively rare habitat and whilst locally Brownsea Island is a very important site for wildlife, Poole Park as an improving habitat is becoming increasingly important for specialist lagoon species and provides a wonderful place for the public to engage with wildlife.
Rare species, such as the Lagoon cockle Cerastoderma glaucum, Lagoon mud snail, Ecrobia ventrosa, and the Lagoon prawn, Palaemonetes varians, live in the muds and salt water of the lagoon; maintaining the levels of salt water by exchanging water with Poole Harbour every month is vital for their survival.
The improvements offered by this project should further enhance the habitat, providing homes for invertebrates in the muds and banks, and for various specialist plants, crabs and fish. This will help to attract more birds that feed on these species, highlighted by the appearance over the last few years of greater numbers of cormorants, egrets and rare species such as the Great Northern Diver.