5. the cumbria tarns project - FreshwaterLife

The Cumbria Tarns
Project
Project Report 2003 - 2009

1. SUMMARY ................................................................................................................................ 6
2. INTRODUCTION .................................................................................................................... 8
2.1. What is a tarn? .............................................................................................................. 8
2.2. How were they formed? ............................................................................................. 9
3. THE DIVERSITY AND FLORA OF TARNS .................................................................... 11
3.1. Upland (oligotrophic) tarns ..................................................................................... 11
3.2. Lowland tarns ............................................................................................................. 12
4. ARE SMALL WATER BODIES IMPORTANT AND ARE THEY THREATENED? .. 14
5. THE CUMBRIA TARNS PROJECT .................................................................................... 16
5.1. When and why was it set up? .................................................................................. 16
5.2. Pillwort survey ........................................................................................................... 17
5.3. Other surveys ............................................................................................................. 17
5.4. Raising awareness ..................................................................................................... 18
6. VOLUNTEERS ........................................................................................................................ 19
6.1. The importance of volunteers to the project ........................................................ 19
6.2. Training volunteers ................................................................................................... 20
6.3. The role of the Project officer .................................................................................. 20
7. TARNS SURVEY METHOD ................................................................................................ 21
7.1. Introduction ................................................................................................................ 21
7.2. Survey method ........................................................................................................... 21
8. TARN SURVEY RESULTS .................................................................................................... 23
8.1. Key achievements ...................................................................................................... 23
8.2. Data analysis ............................................................................................................... 23
8.3. Results and conclusions of first analysis .............................................................. 24
9. THE FUTURE .......................................................................................................................... 26
9.1. How will the information be used? ....................................................................... 26
9.2. Future management................................................................................................... 26
10. ACKNOWLEDGEMENTS ................................................................................................. 28
11. REFERENCES & FURTHER READING .......................................................................... 29

CUMBRIA TARNS PROJECT TIMELINE
2003 The Cumbria Tarns Project, initiated by Cumbria Wildlife Trust (CWT) and
the Freshwater Biological Association (FBA) as part of CWT’s Community
Action for Wildlife programme. The objectives were to repeat the tarn
surveys carried out by Ralph Stokoe in the 1970’s and provide volunteers
with an opportunity to gain experience in surveying freshwater habitats.
2004 Pilot survey undertaken giving volunteers training in freshwater habitat
survey methodology and plant identification.
Twenty-five tarns surveyed and the data entered into the Tarns and Ponds
database.
Seed corn funding secured from English Nature (EN)/Natural England (NE),
Environment Agency (EA) and National Trust (NT), to extend the survey
into the 2005 season.
2005 Tarns Project Officer appointed to undertake surveys and support volunteer
survey team.
Tarns Project Handbook produced setting out the tarn survey methodology.
The survey team of 20 volunteers surveyed nearly 100 tarns and ponds.
Funding secured from SITA and Heritage Lottery Fund (HLF) to extend the
Project until the end of 2008, expanding the remit of the project to contribute to
the Cumbria Biodiversity Action Plan with surveys of oligotrophic (nutrient
poor) tarns and the scarce aquatic fern, pillwort (Pilularia globularia).
2006 The tarns survey team carry out surveys at 96 tarns.
The Project surveys sites with historical records for pillwort, re-finding the
species at eight sites, and discovering it at two new sites.
The Project carried out trial fish surveys with help from the EA, and the
Centre for Ecology and Hydrology (CEH).
2007 104 tarns surveyed.
Fish surveys undertaken at six tarns, attracting a further 11 volunteers to the
Project.
An MSc Thesis, by Birmingham University student Tamsin Douglas compared
plant data collected by the Tarns Project with the records collected by Stokoe
in the late 1970s. Analysis of the data suggested that a number of changes in
the tarn flora had occurred including a decline in species diversity.
2008 The Wildlife Site Selection panel selected 19 tarn sites surveyed by the Project
as new Wildlife Sites using new guidelines refined by the knowledge gained
through Tarns project surveys.
A further 80 surveys completed including Broadcrag Tarn and Foxes Tarn,
the highest named tarns in Lakeland.
Tarns Project commissioned by the EA to undertake surveys of Windermere
for aquatic plants and the Glutinous snail (Myxas glutinosa).

1. SUMMARY
Tarns are a unique feature of Cumbria, contributing greatly to its beauty as well as
being ecologically important. Cumbria has over 3,000 small water bodies, found from
the rugged high fells to richer low lying agricultural land. The diversity in size, shape,
altitude, depth and water chemistry means that many plants and animals find refuge
and thrive in these habitats. They support a huge variety of life, from microscopic
forms to large vascular plants and animals, including fish, amphibians and birds.
Together, the small water bodies support two-thirds of all freshwater plants (at least
240 plant species are associated with tarns in Cumbria) and animal species found in
the county, and support more invertebrates and rare species than rivers.
Despite their diversity and interest, small water bodies are often taken for granted and
have received less protection and interest than rivers and lakes. Nationally, ponds have
been disappearing at an alarming rate through drainage and in-filling. Results from
the UK’s Countryside Survey 2007, carried out by the CEH, show that good quality,
wildlife-rich ponds have gone from many parts of the countryside with only 8% of
ponds across the UK currently in good condition and the biological quality of lowland
ponds declining over the last decade.
The ecological importance of Cumbria’s tarns has been recognised for many years.
The FBA based on Windermere, has been carrying out scientific work on tarns for over
70 years and the Brathay Exploration Group began studying tarns in the 1950’s. In
the 1970’s a local naturalist, Ralph Stokoe, undertook botanical surveys of nearly 400
tarns across Cumbria. His detailed records provide a valuable and extensive source of
information.
In 2003, CWT and the FBA set up the Cumbria Tarns Project. Its aim was to engage
trained local volunteers in re-surveying tarns that had been surveyed 30 years
previously by Ralph Stokoe. Repeating these surveys has provided us with two sets
of data that can be compared and analysed to assess whether species composition
and tarn ecology has changed over the last 30 years, and help determine the possible
causes of this change.
An initial analysis of data has suggested a decline in species richness, particularly
among the submerged and floating macrophyte species. The analysis also showed a
shift in nutrient status in the lowland tarns towards more eutrophic conditions. In the
upland tarns there was no detected change in ecology, however species richness has
declined.
As the project has developed its remit has widened to include surveys of UK Biodiversity
Action Plan (UKBAP) and Cumbria Biodiversity Action Plan (CBAP) habitats and
species, particularly nutrient poor (oligotrophic) tarns and the scarce aquatic fern,
pillwort (Pilularia globularia). We have also undertaken fish surveys and in 2008 carried
out an aquatic plant survey of Windermere.

The Tarns Project is the widest ranging survey of aquatic plants in small water bodies
in Cumbria since Ralph Stokoe’s in the 1970’s. In total we have collected data for 370
tarns, including many that have not been previously studied in detail, thereby adding
to the knowledge of the distribution of aquatic plant species, including some rarer
species such as pillwort. We have collected information on a range of other biological
and environmental data such as management and surrounding landscape.
This information provides an invaluable resource, which can be used to further protect
tarns, particularly through appropriate management. The owners of tarns have been
sent details of the survey and organisations involved in scientific, conservation and
environmental protection work can access the information using a geographical
mapping system and the Tarns and Ponds database.

2. INTRODUCTION
Cumbria is famous for its lakes, which are prominent features of the main valleys, yet
there are many more tarns. Cumbria is one of the most important counties in England
for small water bodies, there being an estimated 3,000+ tarns and pools in the county.
It is difficult to know the exact number because landscapes change and many pools are
temporary. Based at Ferry House, adjacent to the Windermere ferry landing, the FBA
has been carrying out research into the freshwaters in the Lake District since 1929 and
some of its work has had far-reaching implications for water management and supply.
For example, the experiments in Blelham Tarn influenced the design of water storage
reservoirs in the UK and abroad. The Brathay Exploration Group began studying
tarns in the 1950’s, collecting data on the shape and depth of tarns, and analysing their
sediments, which has helped us understand how they were formed.
Staff at the FBA have examined animal and plants in tarns for over 70 years but the
most comprehensive survey of the flora of tarns of Cumbria was undertaken by Ralph
Stokoe, an FBA member and amateur naturalist, who, between February 1975 and
December 1980, surveyed 378 tarns, visiting many of them several times. He recorded
over 200 plant species in total and the results of his work have been collated from his
meticulous field diary and record cards and published by the FBA (Stokoe, 1983.)
In 1983, a survey of macrophytes, Odonata (dragonflies and damselflies), and gastropod
molluscs of 46 water bodies in Cumbria was undertaken as part of an MSc dissertation
(commissioned by Nature Conservancy Council, a predecessor body of EN and NE.
The author produced a classification scheme for tarns based on an analysis of 76 tarns
(Charter, 1984).
2.1. What is a tarn?
The word ‘tarn’ is derived from the Old Norse ‘tjorn’, which was used to describe any
small body of water. It means ‘a small lake’ or more poetically ‘a teardrop’. Tarn is a
regional term used largely, but not exclusively in the Lake District, which along with
many other local names, originated with the Viking invaders who settled in Cumbria
in the tenth century.
There is no precise scientific definition for a Tarn. The dictionary defines them as
small, steep sided mountain lakes or pools and purists might add that the definition
should include that a tarn is formed as a result of glacial activity. However, the term is
used more generally in Cumbria to include ponds and small lakes in both upland and
lowland areas and the Tarns Project adopted this broader meaning.

2.2. How were they formed?
Most tarns were formed as a result of glacial action. When the glaciers and ice sheets
finally receded some 10,000 years ago, they left a landscape of eroded hollows and
valley bottoms broken with hummocks and mounds. The concentration of tarns in
Cumbria owes everything to this scoured, undulating landscape where water can be
trapped and contained.
Many of the highest and most spectacular tarns e.g. Goat’s Water, occupy cirques
scooped from the fells by ice and some are surprisingly deep. Blea Water on High
Street, has a depth of 63 metres, only surpassed by Wastwater and Windermere, and is
the finest example of a cirque lake in England. Other tarns owe their existence to the
deposition of glacial moraines and debris that have dammed valley head streams.
Goat’s Water, Coniston, lies in a long, south facing cirque.

Bogbean, an emergent plant of tarns and wet bogs. It has
erect long-stalked trifoliate leaves (M. Fletcher, FBA).
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Tarns also occur in areas of peat,
for example on the Pennines in
East Cumbria and the Solway
plain, the smaller ones often being
referred to as bog pools. These
contain few plant species typically
with bog moss (Sphagnum species),
common cottongrass (Eriophorum
angustifolium) and bogbean
(Menyanthes trifoliata).
Lower down, man’s influence
is obvious, many tarns having
been created by damming valleys
or enlarged by raising their
embankments to increase storage
capacity for sporting or industrial purposes. Yew Tree Tarn near Coniston was created
as a fishpond by the raising of a stone-faced concrete dam in the 1930’s. Barngates
Tarn was also constructed in 1930’s to supply water to the Drunken Duck Inn and for
fishing. Industries such as mining used the water resources from local rivers and tarns
as their main source of energy. Levers Water sits in the midst of the Langdale crags
and has for centuries provided water for power and processing in the Coppermines
valley near Coniston. Middle Fairbank Tarn and High Dam Tarn were used to power
bobbin mills; once suppliers of wooden bobbins for the Lancashire cotton industry
Bog pool on Torver Common.

3. THE DIVERSITY AND FLORA OF TARNS
Cumbria has a diverse geology and landscape and a wide range of tarn types that vary
in altitude, size, depth, permanence and water chemistry. Those set in high rock basins,
like Angle Tarn, Blea Water, Red Tarn or Goat’s Water, may be the most spectacular, but
lower and more richly vegetated waters like Loughrigg Tarn, Little Langdale Tarn or
Blelham Tarn enhance the landscape of the valley floors.
Standing waters are often classified according to their nutrient status commonly
described by the terms oligotrophic (nutrient poor), mesotrophic (of intermediate
nutrient status) and eutrophic (nutrient rich). The majority of Cumbria’s lakes and tarns
lie within an area formed of hard base-poor rocks that weather slowly and release few
nutrients (mainly calcium, potassium, nitrogen and phosphorus) and are naturally
oligotrophic or mesotrophic.
Aquatic plants are difficult to define precisely since the boundary between the land and
water is not fixed but fluctuates with the season and rainfall. However, a convenient
definition is “plants which normally have at least their lower stems in water during the driest
time of the year” (Halliday, 1999). They include true aquatics i.e. plants that will only
grow in water, emergent plants, and aquatic forms of species also found out of water.
Aquatic macrophytes are aquatic plants visible to the naked eye. They include vascular
plants, some mosses and liverworts (bryophytes) and stoneworts (Characeae), which are
large, structurally complex algae. Aquatic plants can be divided into three categories;
submerged, free-floating and emergent.
Aquatic plants have important roles in the structure and functioning of the ecosystem
and can be used as indicators of the quality/health of the waterbody. They provide
habitat and refuges for fauna, stabilise lake sediments, are integral parts of the food
chain providing food for herbivorous animals and play an important role in nutrient
cycling.
3.1. Upland (oligotrophic) tarns
Upland, oligotrophic tarns (with low nutrient levels and low productivity) usually
occur on hard, acid rocks. Their waters are cold and clear and they support a poor
but distinctive flora with characteristic narrow leaves, tough cuticles and either tight
rosettes of leaves or long linear leaves that offer little resistance to wave action. The
tarn shores are mostly rocky and wave action in these exposed situations means that
floating-leaved or emergent plants are virtually absent or restricted to small sheltered
bays. In the shallow waters, there is typically a zone of shoreweed (Littorella uniflora),
a small submerged plant with a rosette of bright green, narrow cylindrical leaves that
typically develops dense carpets of plants joined by creeping and rooting runners.
Scattered rosettes of the water lobelia (Lobelia dortmanna) often occur in this zone and
the slender flowering stems with their pale blue flowers raised above the surface are a
familiar sight in summer. In deeper water, but often overlapping with the shoreweed,
there is usually a zone of quillwort (Isoetes lacustris). This too has rosettes with long
cylindrical leaves. Also in this zone, are plants with long threadlike or feathery leaves
such as alternate leaved water milfoil (Myriophyllum alterniflorum), bulbous rush (Juncus
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ulbosus) or floating bur-reed (Sparganium angustifolim). Floating leaved species such
as bog pondweed (Potamogeton polygonifolius) are restricted to more sheltered areas.
There are few emergent plants, the two most conspicuous are the blue-green leaves
of bottle sedge (Carex rostrata) and the water horsetail (Equisetum fluviatile) with its
distinctive jointed hollow stems. Most of these species, while common in the lakes and
tarns of Britain’s north west, rarely occur elsewhere in the country.
Lower down, oligotrophic tarns may support submerged plants such as lesser
marshwort (Apium inundatum), floating club-rush (Eleogiton fluitans) and the scarce
aquatic fern pillwort (Pilularia globularia).
3.2. Lowland tarns
At lower altitudes in central and eastern areas, the tarns and lakes are often mesotrophic
or eutrophic (nutrient rich), especially in agricultural catchments; where they receive
sewage effluent; or when they occur on limestone. These typically support a more
varied flora including stands of emergents. The plants of upland tarns occur, but, in
addition, floating leaved species such as yellow water-lily (Nuphar lutea), white water-lily
(Nymphaea alba) and amphibious bistort (Persicaria amphibia) are found, and stoneworts
- a type of complex alga - can be abundant beneath the surface. Pondweeds can be
frequent with a variety of broad and fine-leaved pondweed species, the commonest being
broad-leaved pondweed (Potamogeton natans). Submerged narrow-leaved species, such
as small pondweed (Potamogeton berchtoldii) and blunt-leaved pondweed (Potamogeton
obtusifolius) are also found.
White water-lily, our largest floating leaved flower, with conspicous yellow stamens. Frequent in lakes
and tarns.
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Lowland tarns surrounded by agricultural land tend toward eutrophy and generally
support a diverse flora that includes floating-leaved species such as common waterstarwort
(Callitriche stagnalis) and common duckweed (Lemna minor), and marginal
plants such as floating sweet-grass (Glyceria fluitans), fool’s water-cress (Apium
nodiflorum) and forget-me-nots (Myosotis species). Stands of large, bulky emergent
species such as common reed (Phragmites australis), bulrush (Typha latifolia), branched
bur-reed (Sparganium erectum) and yellow flag (Iris pseudocorus) are typical of these
water bodies. Some display hydrosere development where stands of marginal plants
grade to wet woodland or expanses of mire around the perimeter of the water body,
blurring the boundaries between land and water.
Tarns that have been excessively enriched support large plankton populations and
may be prone to algal blooms. In these conditions, rooted plant communities may be
confined to shallow water due to poor light penetration.
In addition to our native plants, alien species are found in Cumbrian water bodies.
Canadian and Nuttall’s waterweeds (Elodea canadensis and E. nuttallii) have been recorded
since 1874 and 1976 respectively and can out-compete native plants for food and light
and are often abundant in mesotrophic and eutrophic waters. The very invasive New
Zealand pygmyweed (Crassula helmsii), which was absent from the Lake District in
Stokoe’s time occurs in some waters, including Windermere and Bassenthwaite, and
has been found in 3 tarns during the project.
Barngates Tarn was created for water supply and is now used by anglers.
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4. ARE SMALL WATER BODIES IMPORTANT AND ARE
THEY THREATENED?
Open water is a major feature of Cumbria’s environment, covering nearly 1% of the
county’s area (Kelly and Parry, 1990). Many tarns, ponds and pools are designated as
features on internationally important sites such as the Lake District High Fells Special
Area of Conservation (SAC), Subberthwaite, Blawith and Torver Commons SAC, and
North Pennine Moors SAC. Some have been designated as Sites of Special Scientific
Interest (SSSI) in recognition of their national conservation value and many have been
recognised as being of local wildlife importance through the County Wildlife Sites
system.
The importance of freshwaters is recognised in both the UK and Cumbria Biodiversity
Action Plans. Mesotrophic water bodies are a priority habitat in both. Oligotrophic
water bodies are a new priority habitat in the UK BAP and in Phase 2 of the CBAP.
Work over the last few years has demonstrated that small water bodies play a key role
in maintaining biodiversity at the landscape scale (Williams et al., 2004) and ponds have
recently been added to the UK BAP list of priority habitats. Some aquatic species have
been designated as BAP species, including pillwort and great crested newt (Triturus
cristatus).
There are many pressures upon the aquatic environment resulting from human
activities such as nutrient enrichment, agricultural runoff, forestry, industrial pollution,
fisheries and recreational pressures. These impacts affect the quality of the aquatic
environment, although the response of any given water body varies, with some being
relatively resistant to change whilst others are more sensitive.
Lakes naturally evolve over time, gradually filling with sediment and vegetation,
becoming increasingly shallow, which in turn impacts on their ecology. Current theory
suggests that most natural waters are initially oligotrophic and naturally become more
nutrient rich with time, though this trend can be very slow in exposed upland tarns.
The impacts of human activities such as intensive farming and sewage effluent often
accelerate this natural evolution, which are then reflected in changes in the biodiversity
of the water body. In water bodies that are heavily enriched as a result of human activity,
biodiversity is depressed because planktonic and filamentous algae (blanket-weed)
increase rapidly at the expense of other aquatic species such as many of the pondweed
Potamogeton and stonewort Chara species.
Eutrophication is often cited as being one of the most important issues currently facing
freshwater bodies. The application of fertilisers and high densities of cows and sheep
are major causes of enrichment of aquatic systems. Nitrate, phosphate, and silt-enriched
waters run off agricultural land into local water bodies, and can impact their ecology.
Greater levels of nutrients encourage the growth of more nutrient demanding, faster
growing plant species, stimulating competition for space and light to the detriment of
less robust, slow growing plants adapted to lower nutrient conditions. Erect, canopy
producing aquatic plants increase with increasing sediment fertility, whereas rosette or
bottom-dwelling growth forms decline. A similar trend is shown with increasing water
turbidity, with only the more robust species flourishing in highly turbid conditions
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often associated with eutrophic conditions. In extreme eutrophication situations very
few macrophytes can survive in the turbid waters resulting from an explosion of algal
growth, and the low oxygen levels which result when blooms die back are toxic to
many aquatic animals, resulting in a general decline in biodiversity. Mesotrophic
waters are particularly vulnerable to increases in nutrient levels.
Climate change is likely to have an effect on the chemistry and the biology of the
tarns. Warmer year-round temperatures and corresponding phenological (phenology
is the study of periodic plant and aminal life cycle events) change have been widely
reported in the UK, hence climatic changes may already be having an impact on aquatic
communities. Changes in temperature and earlier growing seasons will impact the
biomass and distribution of macrophytes and may encourage survival and growth of
alien species. Impacts from rising temperatures may mimic or exacerbate some of the
effects of eutrophication, stimulating algal blooms.
On a more local scale, factors such as grazing pressure by waterfowl can have a serious
impact on the aquatic flora of a tarn, enrichment around shoreline roosting areas can
account for localised raised nutrient levels. It is suggested that waterfowl can contribute
to loss of reeds around some water bodies. The reduction in stock grazing in Cumbria
following the Foot and Mouth outbreak in 2001, may also have had an impact on the
tarn edge vegetation, as the lighter grazing pressure would encourage a greater range
of more palatable species to survive.
Invasion by alien species represents a significant long-term threat to standing waters
because once established their elimination may prove impossible. Canadian and
Nuttalls waterweed are already firmly established in many of lakes and tarns, often
replacing native species such as pondweeds. New Zealand pygmyweed is very
invasive and can rapidly colonise a water body, affecting the quality of the water
and preventing the growth of other plants. It has already invaded a number of lakes
including Bassenthwaite Lake, Coniston and Derwent Water but so far has spread to
only a few tarns. Parrot’s feather (Myriophyllum aquaticum), another aquatic invasive
was found in one pond during the survey. These and other species may benefit from
warmer winters.
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5. THE CUMBRIA TARNS PROJECT
5.1. When and why was it set up?
The Cumbria Tarns Project started in 2003 as part of CWT’s Community Action for
Wildlife programme. Freshwater was one of three areas (the others being marine
and road verges) devised to provide Trust members and others with opportunities to
experience and learn about natural environments. The idea for the Project arose from a
partnership between CWT and the FBA. As a result, they formed a specialist Freshwater
Group, which was made up of organisations and individuals with an interest in the
freshwater environment including the FBA, EN (now NE), the EA and the CEH.
The project had two clear objectives: –
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1. to resurvey tarns that had been surveyed by Ralph Stokoe in the late
1970s;
2. to provide volunteers with an opportunity to discover more about
Cumbria’s tarns, gaining experience in surveying freshwater habitats
and species.
By re-surveying Stokoe’s work, comparisons could be made between the two sets of
data, to examine changes in the species composition and tarn ecology over 30 years.
Whilst there have been many studies of the larger lakes, the smaller tarns and ponds
had, in comparison, been neglected. The Tarns Project was the largest systematic study
of small water bodies in Cumbria since Ralph Stokoe.
A pilot Tarns Project took place during the field season of 2004, to test survey methods
and assess the amount of volunteer interest in survey work on plants in tarns. It also
enabled CWT and the FBA to organise training courses and so help volunteers to gain
confidence in surveying tarns. This pilot was popular enabling the Project to obtain
funding for a part-time Project officer for the 2005 season. The Project officer undertook
survey work and provided support for the volunteer survey team, for example, by
arranging permissions from landowners. 2005 turned out to be another successful
season, with 20 volunteer surveyors surveying nearly 100 tarns and ponds.
Because of the popularity and success of the Project, CWT made successful proposals
to SITA Environmental Trust and the Heritage Lottery Fund to continue the project
until the end of 2008. The bid set out how the surveys of meso-oligotrophic tarns could
contribute to the UKBAP and the CBAP, and establish the distribution of the scarce
aquatic fern pillwort in Cumbria.

5.2. Pillwort survey
In 2006, specific surveys for the aquatic fern pillwort (Pilulifera globularia) were carried
out. Largely as a result of drainage, pillwort is declining throughout its range in
northern Europe and all remaining sites in NW England are in Cumbria.
Pillwort has been recorded historically for about 30 sites in Cumbria, dating back to the
nineteenth century, often with scant location details. Using these records and Stokoe’s
data we identified tarns that appeared likely to support pillwort.
Pillwort, a nationally scarce aquatic fern.
Tarns in ten 10km squares were surveyed in 2006, and the plant was found at eight
sites, and two new sites where it had not previously been recorded. Surveyors made
notes on impacts and management contributing to the condition of the tarn, such as
disturbance, water level and the presence of invasive species, which may affect the
growth and continued presence of pillwort.
5.3. Other surveys
In 2006, some trial fish surveys were undertaken with help from specialists at the EA,
the CEH and the FBA. This proved popular with volunteers and, in 2007, surveys at
six sites were undertaken during the summer at which fish lengths and weights were
recorded and scale samples taken for fish age determination.
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In 2008, the Tarns Project was commissioned by the EA with additional funding from the
Lake District National Park (LDNP) to complete a macrophyte survey of Windermere.
This was led by a aquatic macrophyte specialist surveyor, who had started the survey
in 2006. Members of the tarn
survey team had assisted
during the 2006 survey and
were involved again in 2008.
The survey was carried out
from a small boat that moved
in and out from the shore
along transects. A bathyscope
(a glass bottomed viewing
bucket) was used to record
the submerged aquatic flora
as the boat moved along each
transect. The primary purpose
of the survey was to identify
areas of high conservation
value indicated by species rich
assemblages or the presence
of scarce species such as
six-stammened waterwort
(Elatine hexandra), which will
help inform the EA and the
LDNP in their conservation
work on Windermere.
5.4. Raising awareness
CWT and FBA have promoted the project through talks and presentations throughout
the county and press coverage including BBC’s Countryfile. In association with the
Friends of the Lake District (FLD), CWT ran a successful Festival of the Tarns for two
weeks in 2006 to raise awareness of the habitat. This involved guided walks, a series of
evening talks and ‘taster’ days for the public to look at tarns and pools.
A book, ‘Tarns of the Fells’, compiled by a team led by FLD, but involving CWT and
FBA was published in 2005, which together with a website, www.tarnsofthefells.org.uk,
raised the profile and public awareness of tarns.
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Six-stammened waterwort, an inconspicuous plant found on
mud, sand or gravel in shallow water. The Lake District is a
stronghold for this nationally scarce plant.

6. VOLUNTEERS
The Project was initially conceived as a volunteer-based survey, with the aim of
engaging local people in surveying and experiencing freshwater habitats. We have
been lucky enough to have engaged a team of around 30 people who have contributed
to the project. Some of these have surveyed just one or two tarns, but the core team of
about 12 people regularly survey many more than this.
These people come from all walks of life. Some are Wildlife Trust members and staff
who wanted to find out more about freshwater life. Others work professionally in the
freshwater field and wanted to get involved in the project. We also have graduates
and MSc students who want to improve and use their field skills and get experience of
surveying, and local naturalists who are generally interested in the natural world and
undertake recording in the County.
Training day at Loughrigg Tarn.
6.1. The importance of volunteers to the project
The Tarns Project would not have been possible without the participation of the survey
team of dedicated and enthusiastic volunteers. The volunteer survey team conducted
nearly 400 surveys of some 370 tarns. Volunteers also contributed by contacting
landowners, and inputting survey data. The volunteers were highly motivated, often
had local knowledge of the area they were surveying and in some cases had contacts
with local landowners. The contribution of volunteers was integral to the Project.
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6.2. Training volunteers
Most of the volunteers were keen botanists, some with experience of working on local
floras or other recording projects. However, specialist training in the survey of aquatic
macrophtyes, including survey methodology and the identification of difficult aquatic
plant groups, was needed. This was vital to ensure survey standardisation, recording
data that enabled comparisons with Stokoe’s results and with future surveys.
The Pilot survey in 2004 helped to identify the knowledge and skills requirement
for the survey and ensure that volunteers were then provided with all the necessary
information on survey methodology, identification skills, equipment and training.
In the early stages of the Project training courses were offered to increase survey and
plant identification skills and to build confidence in identification of the more difficult
plant groups. Training courses also provided a chance for meeting other members of
the survey team.
6.3. The role of the Project officer
CWT, the FBA and the Volunteer Co-ordinator for the Community Action for Wildlife
Project provided the necessary support and coordination in the initial stages of the
Project. In 2005, a Tarns Project officer was appointed whose duties have included;
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• Providing a contact at the Wildlife Trust.
• Providing support to the volunteer survey team.
• Training volunteer surveyors.
• Arranging access with landowners.
• Providing maps for surveyors.
• Co-ordinating identification and verification of plant specimens.
• Liaising with Plantlife, LDNP, EA and consultants for specialist surveys.
Project officers have also provided regular feedback to the survey team, with updates
on Project progress and how the information they had collected was being used.

7. TARNS SURVEY METHOD
7.1. Introduction
It was important that the information collected for each site was comprehensive,
accurate and standardised. A standard survey method was therefore used to ensure
consistency between different surveyors and allow valid comparison to be made
between sites and over time. This was achieved through training and, in the early
days of the project, less experienced volunteers being mentored by more experienced
surveyors. In 2005, a Project handbook was produced that described the survey
methodology and the surveyors’ role in the Project.
7.2. Survey method
A standard method for surveying aquatic macrophytes was developed by the former
Nature Conservancy Council (NCC) and by Scottish Natural Heritage (SNH) for their
extensive survey of freshwater lochs in the 1980’s and 1990’s. The method entailed
walking the perimeter of the water body to record shoreline and shallow water
vegetation. Deeper water was sampled by means of a grapnel thrown in from the bank
at intervals. The cover of all plants was recorded using the DAFOR scale (Dominant,
Abundant, Frequent, Occasional, Rare). The main stands of vegetation were mapped
and target notes were written to give a record of the vegetation, environmental data and
any other useful information. Photographs of the tarn, and any notable or interesting
plant or animal species seen were taken.
Permission of the landowner was obtained before visiting every tarn. Prior to survey,
surveyors would generally read any existing information about the water body,
familiarising themselves with species and features that have been previously recorded.
Most of the surveys were carried out between June and October, usually by groups
of two or more surveyors, all of whom had received training and were competent
botanists.
For the purposes of the Project we defined a pond or tarn as a water body that contains
water for at least four months of the year. For practical reasons we did not survey the
larger lakes in Cumbria, except for Ennerdale Water and part of Windermere; aside
from this no upper or lower limits to the size of a water body were set. The water
bodies surveyed have mainly been tarns, but have also included reservoirs and small
pools.
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The principal aims of the project was to repeat the botanical surveys carried out by
Ralph Stokoe, therefore at a minimum it was necessary to record all aquatic plant
species at each tarn. The range of information recorded was however wider than that
collected by Stokoe and included;
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• A record of all plant species, and their abundance.
• A detailed map of vegetation stands showing the extent of marginal,
emergent and aquatic plant species with dominant species codes.
• A completed survey form recording environmental data such as water
clarity and substrate, any management and impacts, and adjacent
habitats.
• Biodiversity Action Plan species.
• Information needed for the assessment County Wildlife Site status.
• Written description of the tarn.
Fish surveyor setting a fyke net at Blea Water.

8. TARN SURVEY RESULTS
8.1. Key achievements
• 390 macrophyte surveys of 370 water bodies.
• The formation of a team of trained tarn surveyors.
• Assisting with the completion of a successful MSc thesis using
comparative data to highlight changes in plant communities over 30
years.
• A completed Pillwort survey confirming the species at 8 sites and
adding 2 new sites.
• Trial fish surveys completed.
8.2. Data analysis
One of the principal objectives of the project was to repeat surveys of tarns that had
been surveyed by Ralph Stokoe in the late 1970’s. This has provided us with a dataset
of tarn data that can be used in comparative analysis.
A first stage analysis of the data, has been carried out by Tamsin Douglas, an MSc
student at the University of Birmingham (Douglas, 2007). The study analysed records
from Stokoe’s surveys and selected records from the first 3 years of the Cumbria Tarns
Project (2004-06) in an attempt to assess whether the botanical quality of tarns within
the Lake District National Park has changed, and to determine the nature of any such
changes. PLEX scores (Duigan et al., 2006) and Ellenberg values for moisture, pH
and fertility (Hill et al., 1999) inferred from tarn species lists were instrumental in
this analysis. Tarns were also classified into ecotype groups based on their botanical
composition, following the key in Duigan et al. (2006).
A dataset of 93 tarns was sub-divided into ‘upland type’ and ‘lowland type’ tarns as it
was anticipated that any change in the trophic status of tarns would be more evident
in the lowland sub-group due to proximity to direct sources of nutrients, such as
agricultural runoff.
The study compared several aspects of the data from the two survey periods,
including:-
• Changes in distribution of individual species within the study area.
• Community structure (in terms of growth form of constituent plants),
particular among rosette forming species.
• Species richness of each tarn (both in terms of all macrophytes, and of
‘true aquatics’).
• Ellenberg scores for each tarn, for fertility, pH and moisture (Hill et al.,
1999).
• Ecotype scores for each tarn based PLEX values for floating and
submerged species only, following Duigan et al. (2006).
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8.3. Results and conclusions of first analysis
The results summarised in this report should be regarded as interim – and it is intended
that the full data set should be subjected to further analysis as the next stage of the
project. The results of the Douglas analysis are presented below:
The most distinctive trend in the data is the decline in species richness, particularly
among the submerged and floating macrophyte species.
The average number of aquatic plant species recorded from each tarn has changed,
falling from 12.08 in the late 1970’s to 11.11 in the 2004-06 data. The average number of
‘true aquatics’ has fallen from 7.63 per tarn in Stokoe’s data to 6.7 in the recent surveys,
being on average almost one less aquatic plant in every tarn surveyed.
This change was most apparent in the upland group of tarns where species richness overall
declined from 65 species to 54 species, including 7 new species and 18 not re-recorded in
the 2004-06 surveys. A smaller decline was observed in the lowland tarns where species
richness decreased from 76 species to 71 species (of which 8 species were newly recorded
and 13 not re-recorded in the 2004-06 surveys). Most species not re-recorded were locally
uncommon, having been recorded by Stokoe in only one or two tarns.
There have been changes in community composition with declines in floating leaved
and submerged species, particularly the rossete-forming species such as quillwort.
Conversely, there has been a notable increase in the number of emergent species and
slight increases in free-floating plants and charophytes.
In the lowland sub-group there was a shift in nutrient status towards more eutrophic
conditions. In the upland sub-group, however, there was no detected change in nutrient
status.
There have been apparent changes in the distribution of several species since Stokoe’s
survey. In lowland tarns, species often associated with mesotrophic waters, such as
Potamogeton obtusifolius, P. berchtoldii and Elodea spp, have almost doubled in range.
Quillwort, a species with a strong northern distribution in the U.K. and characteristic
of oligotrophic waters, has declined substantially across the study area (upland and
lowland tarns) from 29 to 17 tarns. Lythrum portula, a plant generally encountered in
draw-down zones particularly of mesotrophic waters has also declined significantly, as
has Ranunculus peltata and Callitriche spp, pioneer species of bare mud and occasionally
inundated ground.
In lowland tarns, introduced (alien) species have also increased substantially, though
they still only account for a small percentage of the total species present.
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Species with a southern distribution (which includes all 3 non-native species
encountered in these surveys) in the UK have increased across the dataset, and species
with a typically northern distribution in the UK have decreased substantially. When
these records are split into upland and lowland groups, the trend for lowland tarns
matches the pattern seen above. In upland tarns, however, both northern and southern
groups of species are in decline.
The observed decline in species richness may be slightly exaggerated in the analysis as
a consequence of survey frequency. Stokoe carried out his surveys at different times of
the year and often visited sites more than once, resulting in some tarns having a species
list collated from 2 or more surveys. The 2004-06 surveys, with two exceptions, involved
only one site visit and as such provided just a snapshot of the flora at that time. These
two factors would imply some level of bias towards greater species richness in Stokoe’s
dataset, though it is worth noting that surveys carried out as part of the Cumbria Tarns
Project involved two, or frequently several, individuals thereby reducing the chance of
missing any species.
Quillwort, a rosette forming species characteristic of oligotrophic tarns.
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9. THE FUTURE
9.1. How will the information be used?
The Tarns Project has collected data for 370 tarns, including many that have not
been previously studied in detail, adding to the knowledge of the distribution of
aquatic plant species, including some rarer species such as awlwort and pillwort.
The survey data has expanded the level of scientific information available to officers
from conservation organisations and can be used to protect them further, through
management, designation and planning.
The species data collected by the Project, together with data from previous surveys
has been entered onto the new Tarns and Ponds database designed by Tony Marshall,
and is available through the Tarns of the Fells website, www.tarnsofthefells.org.uk.
Conservation bodies and others can search the database for information on specific
ponds and tarns or species of interest.
Copies of our survey reports have been sent to landowners including the National
Trust, United Utilities, the LDNP, and many private landowners. The survey results
will help assess whether existing management regimes are appropriate.
9.2. Future management
It is hoped that the results of the survey will help to inform any decisions made about
the management of Cumbria’s tarns and how best to protect them in the future. Results
can also be used to inform catchment-wide strategies to protect and enhance upland
environments.
Aquatic macrophytes in tarns are indicators of the health not only of the waters
themselves but also of their surrounding environment. The health of a freshwater body
is directly related to the state of its catchment and this forms the basis for European
legislation to protect freshwater systems, the Water Framework Directive (Directive
2000/60/EC).
The information is useful for the decision-making bodies such as the EA, NE and the
LDNP. They may use it, for example to monitor change, particularly on designated
sites, or deciding whether to issue consents and planning permissions.
The data is also useful for organisations carrying out research on freshwaters such as
the FBA and the CEH.
CWT is regularly consulted about planning applications for works proposed throughout
the county. Tarn data collected is already being used by CWT officers and others to
advise landowners, developers and planners if a proposed development would impact
a site. If the work proposed is potentially detrimental, we can help to ensure that the
water body is protected.
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Data collected by the project has been used to develop robust guidelines for the
selection of new County Wildlife Sites in Cumbria. These guidelines have been used
to assess tarns surveyed by the Project, with 19 tarn new sites selected as County
Wildlife Sites. County Wildlife Sites are the most important places for wildlife outside
legally protected land such as SSSIs or SACs. The sites in Cumbria are part of a series
across Britain. The designation of these sites complements the protection afforded by
statutory sites, primarily by identifying areas that have substantive wildlife interest
and therefore merit some form of protection, primarily through the planning system.
Data collected from our surveys has contributed to the national ponds database held
by Pond Conservation – a charity devoted to the survey, restoration and monitoring
of small water bodies. The results of the project have contributed to meeting both UK
and CBAP habitat (oligotrophic and mesotrophic standing waters) and species targets
including pillwort.
There is an increased degree of concern about invasive alien plants in water and the
records resulting from the project have already contributed to the county’s knowledge
of the spread of invasive species and some advice has been given to tarn owners on
management and the need to control/remove these species.
It is hoped that the work of the Tarns Project will continue in the future. There is scope
for further analysis of the macrophyte data collected by the Project, particularly the data
collected during 2007 and 2008 seasons. This is now planned for March and April 2009.
There is a core of volunteers keen to survey tarns and the FBA and CWT are looking
at ways of continuing to support them. We are currently exploring opportunities for
further work on tarns, which might include; i) addressing particular aspects of the
aquatic plants, ii) extending the project into surveys of fish species (possibly paying
particular attention to BAP species) or iii) extending the work into surveys of particular
invertebrates - again possibly BAP species. Other projects may involve using the data
to improve the management of tarns and their catchments.
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10. ACKNOWLEDGEMENTS
The Tarns Project has formed links and worked with a variety of organisations including
Natural England, The National Trust, the Lake District National Park, the Environment
Agency, United Utilities, Forestry Commission and Plantlife.
Specialist training in aquatic plant identification was provided by a number of local
and national experts including the BSBI county recorder who also accepted our plant
specimens for verification. Staff at the FBA, CEH, and the EA also supported the
Project.
The Project has been sponsored by a number of funding bodies, principally by the
Heritage Lottery Fund and SITA UK. SITA allocates funding through the Landfill
Communities Fund for community life and wildlife projects, which help to achieve
the UK’s Biodiversity Action Plan. Funding has also been provided by the National
Trust, Lake District National Park, The Environment Agency, Natural England and the
Joseph and Nancy Burton Charitable Trust.
We are very grateful to the many landowners who have allowed us access to their land
to carry out the surveys. They have included large owners such as the National Trust,
Forestry Commission, United Utilities, the Lake District National Park, many private
estates and a myriad of small landowners.
Finally, we must mention again the vital role that the volunteer surveyors have played
in the Project. Without their enthusiasm and dedication the Project could not have
achieved what it has and they have demonstrated again the important role that
volunteers play in conservation and set a model for future projects.
Map showing distribution of lakes and tarns in Cumbria.
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11. REFERENCES & FURTHER READING
Charter, E. (1984). A Survey, classification and evaluation of small open waters in
Cumbria. London: University College. MSc Dissertation.
Douglas, T. (2007). Detecting changes in the aquatic flora of the tarns of Cumbria’s
Lake District. University of Birmingham. MSc Dissertation.
Halliday, G. (1997). A Flora of Cumbria. University of Lancaster, Centre for North-West
Regional Studies.
Halliday, G. (1999). Cumbria’s Aquatic Plants. Cumbrian Wildlife. No.53.
Haworth, E., de Boer, G., Evans, I., Osmaston, H., Pennington, W., Smith, A., Storey, P.
& Ware, W. (2003). Tarns of the central Lake District. Ambleside: Brathay Exploration
Group Trust.
Kelly, P.G. and Perry, K.A. (1990). Wildlife habitat in Cumbria. Research and Survey in
Nature Conservation No. 30. Peterborough: Nature Conservancy Council.
Palmer, M. (1992). A Botanical classification of standing waters in Great Britain.
Peterborough: Nature Conservancy Council. Research and Survey in Nature
Conservation, No. 19.
Preston, C.D. and Croft, J.M. (1997). Aquatic plants in Britain and Ireland. Colchester:
Harley Books.
Ratcliffe, D. (2002). Lakeland, The Wildlife of Cumbria. The New Naturalist. Harper
Collins.
Rodwell, J. Ed. (1991). British Plant Communities. Volume 2, Mires and heaths.
Cambridge University Press.
Stokoe, R. (1983). Aquatic macrophytes in the tarns and lakes of Cumbria. FBA
Occasional Publication No 18. Ambleside: FBA.
Williams P., Whitfield M., Biggs J., Bray S., Fox G., Nicholet P., and Sear D. (2004).
Comparative biodiversity of rivers, streams, ditches and ponds in an agricultural
landscape in Southern England. Biological Conservation 115, 329-341.
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The Cumbria Tarns Project has been made possible through the generous
donations of both money and time from the following organisations: