Protecting Wildlife for the futureRegisered charity no. 222212
Derbyshire Wildlife Trust was commissioned to survey the lake located within Alvaston Park as part of the Wild About Ponds Project in order to provide management recommendations based upon the findings of the survey. It would also enable a comparison of survey results against data obtained as part of the 2004/5 Derby City Pond Survey.
Map 1 shows the location of the lake which is present within Alvaston Park, a public park situated approximately two miles to the south-east of Derby city centre adjacent to the River Derwent.
Construction of the lake began in 1922 and was formally opened in September 1923 with a café pavilion and boat house with rowing boats and paddle boats for hire. The racing of model boats and yachts on the lake was a favourite pastime. By 1934 the lake was reported to be badly polluted from the Cotton Brook which flowed into the lake.
The site is owned by Derby City Council and managed by the City Council Parks Department. There is an Alvaston Park Friends group who are actively involved in organising and hosting public events throughout the year. The Park is very popular and well used by the public. The lake is known to contain large carp, roach and perch with fishing permitted on a day ticket basis.
The lake attracts large numbers of waterfowl including Canada Geese, Greylag Geese, Coot, Mallard, Moorhen, Mute Swan, Tufted Duck, Heron and Great Crested Grebe, many of which use the wooded island in the centre of the lake for nesting. Occasional sightings of terrapins on the island are reported.
The proximity of the lake to the River Derwent and the presence of a number of mature trees makes the site an excellent foraging area for bats.
There is an ongoing problem of algae on the surface of the lake and in an attempt to reduce the problem, mesh bags stuffed with barley straw were introduced into the lake by the Parks Department on 16th March 2012
The lake covers an area of approximately 31,296 square metres and, as such, is outside the definition of a pond. It was not possible therefore to obtain a PSYM value for the site although a survey of the aquatic plants, invertebrates and amphibians was still carried out for the site.
An appraisal of the ecological value of the lake was undertaken from which it was possible to obtain a current list of aquatic plants species associated with the site, a measure of aquatic macroinvertebrate activity and use of the lake by amphibians This would enable a broad ecological evaluation of the lake to be made together with management recommendations to enhance the biodiversity value of the site.
The lake was subject to a torchlight survey for amphibians on 12th April 2011 and a further survey was undertaken on 24th August 2011 to record aquatic plants and macroinvertebrates.
The following information was gathered for the pond:
Grid reference: SK 37751 34667
Site Name: Alvaston Park lake
Location: Alvaston Park
Owner/site access details: Derby City Council
|Survey Date: 24th August 2011||Surveyors:||Trevor Taylor (Derbyshire Wildlife Trust)|
|Altitude: (m)||43m asl||pH:||8.23|
|Shade: % pond overhung:||2%||% emergent plant cover||3%|
|Inflow (absent = 0, present = 1):||1||Pond area (m2)||31,296m2|
|% of pond margin grazed:||0|
Pond base: categories into one of three groups; 1=0%-32%, 2=33%-66%, 3=67%-100%
|Clay/silt:||1||Sand, gravel, cobbles:||1||Bed rock:||1|
|Emergent plants||Rarity Score||Trophic Ranking Score|
|Epilobium hirsutum, Great Willowherb||1||-|
|Iris pseudoacorus, Yellow Iris||1||-|
|Juncus effusus, Soft Rush||1||-|
|Lycopus europaeus, Gipsywort||1||-|
|Phragmites australis, Common Reed||1||7.3|
|Ranunculus sceleratus, Celery-leaved Buttercup||1||10|
|Rorippa palustris, Marsh Yellow-cress||1||-|
|Typha latifolia, Bulrush||1||8.5|
|Floating leaved plants|
|Lemna minor, Common Duckweed||1||9|
|Ceratophyllum demersum, Rigid Hornwort||2||10|
Number of emergent and submerged species - 9
Number of uncommon species (with a rarity score of 2 or more) - 1
Trophic Ranking Score - 8.96
|Group 3 taxa (BMWP: 7)|
|Caenidae - Mayfly|
|Group 4 taxa (BMWP: 6)|
|Unioniidae - Mussel|
|Coenagriidae - Damselfly|
|Group 5 taxa (BMWP: 5)|
|Planariidae - Flatworm|
|Gerridae - Water bug (water skater)|
|Pleidae - Lesser Water Boatman|
|Corixidae - Water Boatman|
|Dytiscidae - Water beetle (diving)|
|Group 6 taxa (BMWP: 4)|
|Baetidae - Mayfly|
|Piscicolidae - Leech|
|Group 7 taxa (BMWP: 3)|
|Lymnaeidae - Snail|
|Physiidae - Snail|
|Glossiphonidae - Leech|
|Asellidae - Crustacean (water slater)|
|Group 8 taxa (BMWP: 2)|
|Chironomidae - Fly (Non biting midge)|
|Total No. of taxa||15|
|Total BMWP Score||59|
|No. of OM taxa||1|
|No. of Coleopt taxa||1|
A conductivity test to measure the total quantity of chemicals dissolved in the water returned a reading of 450µS/cm2. This figure indicates that the lake is on the borderline with regard to contamination. Where conductivity is 500-1000 + µS/cm this is usually a sign of some kind of pollution and a perfectly clean water pond would have a figure of 100µS/cm or less. It was noted that in the south-east corner of the lake where waterfowl tend to congregate the conductivity reading rose to around 530µS/cm2
The lake is situated in the north-east corner of Alvaston Park which is well-used by members of the public. A hard-surfaced path runs around the perimeter of the lake which is surrounded by close-mown amenity grassland and areas of tree and shrub planting. A well-wooded island is present in the centre of the lake and a line of mature native black poplar trees occur along the western bank.
The lake is fed by an inflow in the north-west corner and an outflow is located in the north-east corner.
The base of the lake would appear to be formed from concrete overtopped with gravel, especially in the margins. This relates to its original function as a boating lake, which means that there is little opportunity for the establishment of any emergent aquatic vegetation. Attempts were made around 2002/3 to introduce aquatic vegetation on the northern bank of the lake using planting baskets but the success of the planting was severely compromised by the presence of large numbers of waterfowl which occur at the site. Subsequent attempts to introduce aquatic vegetation assisted by protective mesh fencing have been more successful and have resulted in the establishment of four stands of emergent vegetation along the northern shore. The stands are dominated by Common Reed, Phragmites australis, with occasional Great Willowherb, Epilobium hirsutum, Yellow Iris, Iris pseudoacorus, Bulrush, Typha latifolia and Celery-leaved Buttercup, Ranunculus sceleratus. Soft Rush, Juncus effusus, Gipsywort, Lycopus europaeus, Common Duckweed, Lemna minor and Marsh Yellow-cress, Rorippa palustris, are rare with the latter species occurring in cracks in the concrete around the northern margin of the lake.
Rigid Hornwort, Ceratophyllum demersum is locally abundant as a submerged aquatic species, particularly in the southern part of the lake.
A reasonable range of macroinvertbrates were recorded during the netting sampling including the presence of Swan Mussel which was also recorded during the 2004/5 survey. Most of the invertebrates were observed in the vicinity of the stands of emergent vegetation which also provide shelter and nesting habitat for birds as well as cover for amphibians.
This represents a significant overall increase in the diversity of aquatic vegetation and macroinvertebrate activity to that recorded at the site during the 2004/5 Derby City Pond Survey visits.
The site supports a small population of smooth newt with one female recorded on 11th May 2005 during a torchlight survey and 3 females and one male recorded on 12th April 2011. A small amount of frogspawn was also observed in the margin during March 2011. All the amphibian interest is associated with the stands of emergent vegetation on the northern bank.
Large numbers of waterfowl are attracted to the lake with particularly high numbers of Canada Geese, Mallard, Coot, Domestic/Hybrid Ducks and Mute Swan present while Moorhen, Tufted Duck, Greylag Geese, Heron and Pochard occur in lesser numbers. Flocks of Black-headed gull are present, particularly during the winter months. These high numbers of waterfowl considerably increase the nutrient input to the lake which in turn gives rise to the algal blooms and blanketweed growth during the summer months. The presence of fish also contributes to the increased nutrient levels, albeit to a lesser extent.
The waterfowl and fish will also control the numbers and diversity of invertebrates associated with the site through predation.
Below: Canada Geese - 2004
The introduction of barley straw has potential to control the level of algae and blanketweed growth but it needs to be maintained to achieve the desired effect. The problem is noticeably reduced during the colder months of the year.
Due to the combination of high numbers of waterfowl, the presence of fish, particularly large carp, and the nature of the lake bottom which does not lend itself to the establishment of emergent aquatic vegetation necessary to provide habitat and cover for aquatic invertebrates and amphibians, it is unlikely that the lake will ever achieve a high level of ecological interest.. As it would be considered impractical and, arguably, unreasonable to control the numbers of waterfowl and fish it is therefore recommended that a smaller waterbody, designed for the benefit of wildlife, particularly amphibians, should be created elsewhere on the park.
To tackle the algae problem associated with the lake it would require the cause of the nutrient enrichment to be addressed which essentially equates to control of the waterfowl population and removal of fish which as stated above is considered to be both impractical and unreasonable. The establishment of submerged aquatic plants and the establishment of extensive areas of wet soils and marshy vegetation at the lake edge would also help to improve the water quality. However, again due to the presence of high numbers of waterfowl which predate upon any submerged aquatic plants and the lack of areas of soils around the lake margin this approach would not be feasible. Whilst the addition of barley straw can suppress algal growth it has to be realised that it will need to be continued indefinitely. Therefore it is recommended that barley straw should continue to be introduced on a regular basis to suppress algal growth.
Continue to monitor the aquatic vegetation, invertebrate activity and amphibian interest associated with the site and forward the results to the Derby City Pond Warden Association, the Derbyshire Wildlife Trust and the Derbyshire Amphibian and Reptile Group.
Alvaston Park Lake - November 2012