Dr. Rob Stoneman looks at our
lakes and wetlands and
discovers the history of this
fascinating landscape.
Finally
the ice begins to retreat —
a messy, muddy wet failback to the northern stronghold. In its wake, the
retreat left humps of dead stranded ice, torrents of muddy water and a
bare featureless abandoned land. Twenty-cycles of ice and warming had
changed the land forever. The mountainous chain had been scraped to a flat
plateau, torrents of melt-water carving deep valleys and gorges into its
sides. Everywhere, the retreating ice left water in scraped out
depressions and around melting ice-burgs. And into the watery landscape,
life returned, migrating across the still sea-free lowlands separating the
hillier western edge of the continent. The land turned green underwaves of
moss and lichen, heath and birch, pine and heather and finally oak, rowan
and ash.
The
lakes, ponds and pools, edged with reed and sedge and awash with water
plants, rapidly filled with loose sediment, gouged from the rocks by
glaciers and eroded by rivers and streams. Within an instant of geological
time, the post-glacial lake-filled landscape had gone, leaving only the
leaves of a muddy encyclopaedia of lake sedimentto record their brief
splendour. The time of ice and water was over; the recolonisation nearly
complete.
In
places though, the water remained -deeper ponds and lakes neverfilled up;
rivers changed course leaving oxbows and partly flooded water-filled
flood-plains. With the melting of the ice, the sea rose, flooding the
flatlands of eastern England, and all over the land humankind began their
massive process of environmental change: managing water meadows, building
ponds for livestock or simple pleasure, damming rivers to supply water and
later water-power.
And
thus, into this post-glacial wet landscape, a myriad of life thrived on an
ever-changing wetland scene. Floating in the water, algae transformed the
sun’s energy into the base of the freshwater food-chain — food for an
array of water-life from mosquito larvae to fish. The variety is immense
— a single scoop of life-laden water from the Wood Lane Pond gives up
great diving
beetles, greater and lesser waterboatman, frog and newt tadpoles, daphnia
water fleas, dragonfly larvae, stonefly and mayfly nymphs, hog lice, midge
and mosquito larvae, pond snails, worms and nematodes, pond-skaters as
well as a multitude of microscopic life not visible to the naked eye. This
scoop of immense biodiversity forms a rich interlinked web of carnivores,
herbivores and detritus-feeding organisms balanced into a healthy rich
habitat. Some of this life is simply unattractive to human senses; others
are spectacularly beautiful — the predatory dragonfly nymph becomes a
majestic aerial killer snatching insects on the wing. In Cambridgeshire,
reed bed wetlands support the stunningly beautiful, and now extremely
rare, swallowtail butterfly.
Another
significant component to the freshwater scene are fish — much loved by
the angling fraternity and the foundation of a major economic activity in
some areas. The species of fish found depends very much on the type of
water — ponds and lakes are good for carp, tench, roach, rudd and bream.
Game fish —trout, salmon and greyling require high concentrations
of oxygen and are found in cool, fast-flowing streams and rivers.
Of
water and land, amphibians are a source of almost total fascination for
children. Britain’s six native amphibians (common frog, common and
natterjack toads, smooth, great-crested and palmate newts) all face severe
loss of breeding habitats as ponds and wetlands are drained. However, a
mass of spawn in the local pond is one of spring’s delights whilst frogs
and toads keep slugs and other garden pests down to a minimum.
Invertebrates,
fish, frogs and newts —none are as famous as one of our rarer mammaIs:
|
“A
brown little face with whiskers. A
grave round face, with the same twinkle in its eye that had first
attracted his notice. Small
neat ears and thick silky hair."
|
 |
It
was
the
stoical star of Kenneth Graham’s The Wind in the Willows - Ratty -
actually not a rat but a water vole. Living in burrows in the banks of
virtually any river, stream,ditch, canal, lake or pond throughout Britain,
they consume a wetland diet of grasses, rushes and sedges — in part the
reason why water-voles have declined so rapidly as bankside vegetation has
been bulldozed away in a misguided programme of river canalisation. A much
loved water mammal that has declined even more is the fabled otter whose
populations crashed from the 1950s to 1970s mostly as a result of farm
pesticides and habitat loss.
The
otter population crash took this beautiful mammal close to extinction, a
situation mirrored by one of our most spectacular wetland birds, the
bitten. Bittern were once so common that it was considered food fit only
for peasants living in the great eastern fenland. Today less than fifty
breeding pairs remain across the UK; habitat loss is blamed. Other wetland
birds remain more common — ducks, grebes, kingfishers, waders, herons
and gulls. Indeed, a wetland nature reserve is a bird-watchers paradise
— a paradise that was once a common part of the British countryside.
| Today, wetlands are rare and wetland wildlife in decline. Drainage, pollution and natural processes (wetland succession) have led to a massive reduction in our wetland habitats. |  |
InSheffield,
the Lower Don valley has long since been drained of its wetland heritage.
Yet, in the abandoned dams, a small vestige of that heritage has returned.
A gentle stroll around one of our dams might reward the senses with a
family of mallard, an agitated moorhen, the air dancing with flies preyed
upon by dragonflies, swifts and swallows, and in the shallows, a
beautifully marked olive green and flecked yellow pike patiently waiting
to pounce.
With
considerable effort going in to clean up our rivers, we are witnessing the
return of the otter. From near extinction, otters are expanding their
range and have been recorded on the Upper Don. The Wildlife Trusts and the
Environment Agency work together on a national species recovery programme
building otter holts, road underpasses, recording their movements, and
spreading the word. Our sister Trust, Yorkshire, have two otter officers
focusing on improving habitat to link up the presently isolated Yorkshire
populations — could we see otters at Kelham?
In
this Trust, attention is focused on our Wild Web 2000 of improving streams
and ponds. Pond improvements at Crabtree, Lees Hall, Wood Lane, Black Bank
and Sunnybank have all been undertaken to reverse the wetland wildlife
decline. A much more dramatic turnaround could be achieved by working with
planners and house builders to use wetlands to improve urban hydrological
systems. Storm-water overflows could be reduced by sending storm-waters
through ponds and swales, across greenspace or by using porous tarmac. At
source, natural solutions provide much cheaper, attractive and often more
effective ways of dealing with problems. Wastewater from baths, showers
and sinks need not be mixed with sewage for treatment but channelled
though reed-beds for natural purification. Imagine a part of your local
park as landscaped area of trees, ponds, reedbeds and streams — all
working to clean your waste-water, control flooding, and of course,
bursting with a mass of wetland life.
We
have a long way to go to persuade the traditionalists although we have
begun to attempt widespread implementation on the Manor and Castle
environment programme. As important are garden ponds: one of the most
important habitats for garden wildlife. Imagine again — a hundred
thousand gardens each with their pond—the wildlife gain would be
immense. Next year, the Wildlife Trusts launch their Gardening Action for
Wildlife campaign nationally. Kingfisher readers, of course, are well
versed in the art of wildlife gardening.
The
present post-glacial landscape began as a watery place; our damp climate
kept the land wet, so it is no surprise that some of Britain’s finest
wildlife is wetland-based. The return of the otter gives us great
encouragement that wetland wildlife can return. Often it’s not such a
complex process: make the land wetter and the wildlife will return.