The Newchurch & Arreton News article - Nature on our doorstep

Below is an article from the February 2019 "The Newchurch & Arreton News" Booklet, which is available from the Arreton Store, Post Office.

Nature on our doorstep

The Eastern Yar, the longest river on our Island rises in the southern chalk downs and eventually reaches the sea some 12 or so miles downstream at Bembridge. Along the way it initially creates a rich variety of wildlife habitats including old meadows and, after it is joined by the Upper Yar near Budbridge, the flood plain of the river widens, flowing through a flood plain that supports marshes and wet grassland.

Eastern Yar - Arreton - Photograph By Melvyn Pettit

The old railway line follows the course of the Eastern Yar for this part of the valley and significant changes were made to the course of the river to provide drainage of the flood plain and enable construction of the railway. The drainage channel at Moreton is a reminder of the work undertaken at that time. Downstream, the valley between Newchurch and Alverstone contains some of the most important wetlands in the (Eastern) Yar valley including Alverstone Marshes which is a Site of Special Scientific Interest. This part of the valley has deep deposits of fen peat that have preserved archaeological remains dating back into pre-history. 

Red Squirrel – Alverstone Marsh Hide – Photograph By Melvyn Pettit

To the south, the valley sides rise steeply from the flood plain to create distinctive bluffs known as Lynches, many of which support ancient semi-natural woodlands such as those at Lynch Copse, Newchurch. The lower end of the Eastern Yar Moors is marked by the historic weir at Alverstone Mill which creates a trap for silt and as a consequence reduces the depth and area of open water limiting the suitability for fish. Below the weir the valley widens further, forming the Eastern Yar Levels. Gradients are very low and regular dredging of the river has left a deep channel below the flood plain. As a result remaining wetland habitats tend to be located around the edge of the flood plain where springs and seepages arise at the foot of the steep lynches or bluffs such as Alverstone Lynch and Borthwood Lynch.

The marshes below Borthwood Lynch on the south side of the flood plain are managed by the Wight Nature Fund as a nature reserve known as Alverstone Meads whilst further areas of the flood plain are managed by the Wildlife Trust as a nature reserve. It is at this point the need for a co-ordinated management of the Eastern Yar becomes even more evident if nature is to remain in balance. 

Abstraction of water from the water for public supply occurs at a water treatment works located at Burnthouse Weir (just downstream from Longwood Bridge) and this can leave flows severely depleted and in summer flow can be reduced to almost a trickle. Below Longwood Bridge, the flood plain widens further to form the Sandown Levels, an extensive area of flood meadows crossed with drainage ditches and bounded by Sandown and Yaverland to the south and chalk grassland slopes of Knighton and Brading Downs to the north. 

The final lower reaches of the valley - the Eastern Yar Marshes and Harbour, extending downstream from Yar Bridge at Brading to the tidal outfall at Bembridge. This section of the river has mostly been reclaimed from the sea and many of the old tidal creeks can still be seen as reed-filled meanders between extensively grazed wet grasslands. The majority of this area of the flood plain is owned and managed as a nature reserve by the RSPB. Water levels are controlled to create conditions for wetland wildlife in particular wintering waterfowl, breeding waders and reed bed nesting birds such as cetti's, reed and sedge warbler as well as reed bunting. 

The river throughout these lower reaches of its course has an almost flat gradient and water levels in the adjacent marshes are maintained by control structures such as the Great Sluice at Brading and the tidal sluice gates at Bembridge. However these structures trap sediment in the river channel which combined with the low flow rates creates a river with poor aquatic vegetation and invertebrate & fish populations, conditions that are not ideal for some of the birdlife. 

One surprising resident of these lowest marshes in 2018 was a male bittern and its booming call could be heard across the marshes. The bittern is a thickset heron with pale, buff-brown plumage covered with dark streaks and bars. It is a secretive bird, very difficult to see, as it moves silently through reeds at water's edge, looking for fish and amphibians,

Birds - Male Bittern - Photograph from RSPB website

It is thought that there are only 80 breeding males in the UK although it is estimated that a further 500 bittern of both sexes spend winter in the UK between October and March. Some males are polygamous, and occasionally several nests, each built by a different female, are found within the territory of one calling male. The male normally takes no part in nest building or raising the young. 

With acknowledgment to islandrivers.org.uk and the RSPB