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Blacktoft Sands
RSPB Blacktoft Sands nature reserve is a 190 ha at the mouth of the River Trent.
Blacktoft Sands is predominantly reedbed, but there are six artificial lagoons that are important for breeding waterfowl, including avocets (3% UK population), and pochards (2% UK population).
The lagoons are at risk from the accumulation of silt. They are fed by water from the river, and the silt settles out in the lagoons, which gradually infill, diminishing feeding conditions and so the breeding success of the avocets.
The lagoons also face other problems: sluices degrade with age and need replacing, the reed edge gradually encroaches into the lagoons reducing open water for feeding waterfowl, and nesting islands being mud base erode or are colonised by vegetation reducing conditions for nesting.
Actions to address threats
Silt was removed from the 1.5km long feeder ditch that supplies the tidal water to the lagoons. This ensures that water can get onto the lagoons whenever necessary and not just during spring high tides.
Water levels and salinity levels are managed throughout the year by careful adjustment of the sluices
The accumulation of silt has been removed from three of the main lagoons. This has lowered the lagoon bed by an average of 30 cm (the average lagoon depth is only 60 cm). The lagoons were drained after the breeding season, and a bulldozer was used to scrape off the accumulated silt. The lagoon beds were reshaped to improve them for invertebrates, and the edges of the lagoons were reworked to enhance feeding opportunities for birds, such as bitterns. Several new nesting islands have also been created. The silt spoil that was produced has been used to create banks in the reed bed. The sluices on the main lagoons have been replaced, and now allow precise control of the water depths.
Ongoing management of lagoons:
Areas of encroaching vegetation are cleared from the edges of the lagoons each year in rotation.
The breeding islands are cleared of vegetation each year before nesting begins. Those with mud surfaces are dug over to make them attractive to nesting avocets. Those islands that are damaged by erosion are built up and repaired using a digger.
Water levels and salinity levels are managed throughout the year by careful adjustment of the sluices to let water in (or out) to maintain the desired balance.
Public awareness and information
A range of public awareness events takes place each year, organised by the information warden. These include guided walks and open days. Around 900 people attend these events each year.
Survey and monitoring
We monitor salinity levels and water levels in all of the lagoons throughout the year. Breeding and wintering bird populations are counted, and invertebrates are sampled.