River Ouse Corridor comprising over 140miles of main river and tributaries
is an important wildlife site of unique character.
The headwaters of the Sussex Ouse on the
The tributaries of the upper catchment
are mainly small forest streams cutting deep sided valleys through
wooded countryside. These drain High Weald areas of forest and heathland
over a geology of soft sandstones and clays. Though often small and
shallow, they are quick to respond to rainfall and in a few hours
can be transformed to raging torrents. Some of the middle tributaries
are similar, while others are characteristic of lowland streams flowing
more slowly over clays and alluvium. Two of the lower tributaries,
the Bevern and Northend Streams are notable in that they are derived
from springs rising in the chalk of the South Downs, continuing their
journey over greensand and clay in their lower sections.
The principal tributary of the Ouse
is the River Uck, fed mainly by forest streams and similar in character
to the middle reaches of the main river.
The upper and middle reaches of the
main river feature a varied riffle and pool system rich in wildlife,
but stretches above some of the weirs retain the canal like features
of relatively deep and slow flowing water; a legacy from the eighteenth
century when the river was modified for navigation.
The middle Ouse near Isfield
The lower reaches downstream from Sutton Hall Weir are of more uniform
depth (excluding the weir pools and races), typical of a lowland river
traversing an alluvial plain. Below Barcombe Mills the river is tidal
with the flow moderated by a half-weir at Hamsey.
The waters support a diversity of plant
life including water crowfoot and starwort, both listed in Annexe
1 of the EU Species and Habitats Directive as requiring the designation
of a Special Area of Conservation.
A vast number of invertebrates thrive
in the river and its tributaries including mayflies, willow and alder
flies, freshwater shrimps, swan and pea mussels, and some rare types
of water beetle to name but a few.
Bullhead Cottus gobio (Millers Thumb)
The river supports a thriving population of wild brown trout in its
upper reaches and they are found in most tributaries.
It is also notable for its migratory
brown trout which ascend each year to their spawning grounds in the
gravel beds of the tributaries.
It contains most species of coarse
fish indigenous to the British Isles, including rarer fish such as
grayling, barbel, stone loach, river lampreys, and bullheads. Bullheads
are named in Annexe 2 of the Directive and describes as threatened
on an international scale.
The tidal stretches also contain sea
fish that can tolerate the lower salt content here: flounder, grey
mullet, bass, twaite shad, and sea lampreys. Some of these enter the
river to spawn in the brackish water.
The sea trout are especially notable, as they appear to gain the
highest average weight of any population found in the British Isles.
Adult fish vary in size from two or three pounds up to fifteen pounds
or more. It is rare for an angler to catch a fish under two pounds
and the average is over five pounds. Local interest groups consider
the sea trout to be the “jewel in the crown” of the
A Sussex Ouse Sea Trout Salmo trutta
The habitat rich environment of the River Ouse supports a wide range
of bird, mammal, and insect life, including some rare species of
butterfly, the endangered water vole, and of course a considerable
variety of birds including kingfishers, water rail, reed and sedge
warblers, and grey wagtails. These species thrive in the undisturbed
bankside vegetation which provides secluded nesting sites.
The Tidal Ouse at Southease
However, the future of our river is
constantly under threat from a variety of human activities,
not least of which is a proposal to canalise it for the use of motorised pleasure craft. Inappropriate
man made structures, intensive farming methods, weak legislation and
lack of investment in conservation all take their toll. The rise in
population density of the area leads to an increase in water abstraction
and polluting effluents.
Local people and others who value this
ecological heritage have expressed concern at the perceived decline
of its health. OART believes that this concern can be harnessed,
and with appropriate expertise and effort the decline can be halted
THE NATURAL ENVIRONMENT IS OUR GREATEST ASSET. IT MUST BE PRESERVED.