Caithness CWS - A Z - Sutherland - Sutherland Biodiversity Action Plan 2003 - Biodiversity Audit

The Sutherland Biodiversity Action Plan - October 2003
BIODIVERSITY AUDIT - RIVER LOCH AND WETLAND

RIVER, LOCH & WETLAND

Rivers & lochs
Sutherland is dissected by many rivers and burns, which form more fertile incisions into the heart of the county, draining the mountains and moors. Central and South East Sutherland are drained by the Rivers Oykel, Shin, Brora and Helmsdale, which start as peatland burns deep in the heart of Sutherland. Rivers such as the Halladale, the Naver and the Hope drain northwards, whilst shorter, faster flowing rivers and burns drain the hills on the West to empty into the Minch. Britain’s highest waterfall is located at the head of Loch Glencoul, near Kylesku.

The biodiversity of Sutherland lochs and pools is heavily dependent on their chemistry, which in turn is dependent on the surrounding rocks, soils and distance from the sea. The peatland lochs are acidic and nutrient poor (oligotrophic). Bogbean and sphagnum mosses are characteristic, with unique species of desmids occurring in many of the lochs.

Loch Assynt & Quinag

Lochs of intermediate (mesotrophic) nutrient levels have a broad range of species utilising their environment. Insect life is diverse and brown trout, char and eels thrive in such locations.

The limestone lochs of Durness are high in nutrients (eutrophic) and support rare pondweeds. Similarly, lochs situated on machair, where reworked shells form sand and gravel of the loch bottom, are rich in aquatic life. Common gulls prefer freshwater lochs during the breeding season, where they gather in colonies of varying size.

These clean waters are vital for sustaining important
populations of Atlantic salmon, sea trout, brown trout, char and freshwater pearl mussel. Water voles, now lost from much of the British Isles, still occur on headwater burns in the West.

Daubenton’s bats can be seen at dusk feeding over bodies of open water such as slow flowing rivers and lochs.

Black-throated diver

Sutherland’s peatland and hill lochs provide particularly important nesting habitats for red and black throated divers and common scoters, whilst the larger lochs such as Loch Loyal are important breeding and moulting sites for waterfowl including Sutherland’s resident population of greylag geese.

Wetlands
Pockets of open water, reedbed and fen can be found within hollows, and often extend along narrow field and road margins in crofting areas such as between Strath Brora and Strath Fleet. This mosaic of arable land, fen and damp grassland is important for lowland breeding waders such as lapwing, curlew, snipe, redshank and oystercatcher. In Assynt, Loch an Aigeil, na Claise and Awe have relatively large reedbeds that act as roosting locations for many birds.

A diverse and colourful range of aquatic plants is found in these open water and wetland habitats. The wetlands are carpeted with an array of flowers including marsh marigold, ragged robin, northern marsh orchid and water avens. Numbers of amphibians are declining further south, which makes Sutherland an increasingly important area for frogs, toads and newts.