The indusTrial revoluTion^85as the first-recorded nesting site of the black-necked grebe, in 1918, and
of the little ringed plover, in 1938. The surrounding reedbeds are now so
well developed that they are home to over-wintering bitterns. Again, these
great artificial lakes were significant for wildlife almost as soon as they were
completed, although their importance in this respect certainly increased over
time, especially with the development of marginal vegetation. As early as
1853 one of the reservoirs could be described as the ‘the best pike-water near
London’.^49 ‘The only claim of the Marsh Sandpiper (Totanus stagnatilis) to
rank as “British” rests upon a single example which was reputed to have
been shot by Mr Rothschilde near Tring reservoirs... in 1883’.^50 The four
reservoirs were declared a National Nature Reserve in 1995.
Canals are, in Richard Mabey’s words, ‘by definition artificial waterways,
cut by man along routes dictated more by economy than geology’.^51
Although they generally follow river valleys, and may in places be no more
than tidied-up versions of pre-existing rivers, they usually – as with the
Basingstoke canal – track the course of more than one. They connect up
several drainage basins by cutting through the watersheds between them,
seeking out the lowest passage through a separating range of hills. They thus
serve as corridors, linking districts with differing characteristics in terms of
hydrology and geology, and allowing the spread of species into new areas,
reducing earlier contrasts in the biological character of different districts.^52
Prior to the eighteenth century English rivers draining eastwards, into the
North Sea, tended to be richer in species than those draining westwards
into the Atlantic – an ancient distinction, originating in early post-glacial
times, when the latter watercourses had outfalls into the open sea while the
former were connected to the Rhine. Species like bleak and ruffe were thus
confined to the east of the country until the creation of the canal network
allowed them to spread across the central watershed into western waters.^53
Canals, turning England’s separate river systems into a single interconnected
network, also provided opportunities for invasive alien species. Canadian
Pondweed, introduced as an ornamental plant for garden ponds, was
first noted in a canal near Market Harborough in Leicestershire in 1847.
Within 10 years it had spread throughout the waterways of Midland and
southern England.^54 Macan has shown that some sixteen alien species of
freshwater invertebrates have successfully dispersed through the county
via the canal network. One example is the American amphipod Crangonyx
pseudogracilis, which spread rapidly through the canals of central England
between 1937 and 1955.^55 The dispersal of some exotics was aided by the
fact that in industrial areas discharges of warm water from factories raised
the temperature of canals so that, for example, eel grass (Allerisneria spiralis)
became so profuse in the nineteenth century that it had to be dragged out of
canals near Lancashire cotton mills.^56
Railways had a greater visual impact than canals, because of the cuttings,
embankments and tunnels which were constructed to ensure that locomotives
had to cope with minimal gradients. The first to be built, in the period before