Flora and Fauna on the River Barrow
The Barrow is home to countless plants, animals and habitats. The wealth of wildlife present along the Barrow has lead to it’s designation as a Special Area of Conservation (site Code 002162) under the EU Habitats Directive. Only habitats and species of the utmost integrity and importance receive this designation. The river itself holds a number of protected species including lamprey, crayfish, atlantic salmon, sea trout, twaite shad and otter. In the upper reaches of the Barrow, outside the navigation, freshwater pearl mussel occur. This very rare mussel can live to be over 100 years old with a specimen in Finland noted at 162 years.
A diverse range of aquatic plants occur in the river, lateral cuts and canal sections. These include starworts, pondweeds, arrowhead and crowfoot. In the reed fringe plants such as common rush, yellow iris and willow herb provide homes to a diverse range of insects. In fact a recent survey undertaken by Waterways Ireland recorded over 40 different species in the water and riparian fringe. This diversity of plants ensures a wide range of insects, and higher animals such as fish and mammals are regularly found. The reed fringe acts as a buffer to disperse wave energy and therefore is excellent for bank protection.
The habitats to be found immediately along the navigation include river, canal, reed fringe, hedgerow and grassland. Ongoing maintenance of the navigation, in particular the canal stretches, is essential to ensure they remain as vibrant and diverse ecosystems. Maintaining the navigation has even led to the creation of new habitats that are now protected under EU legislation e.g. the islands along the navigation at Carlow were created by re-using dredged sediment to develop valuable terrestrial habitats within the navigation. The hedgerows and woodland along the navigation are hugely important, acting as wildlife corridors and refuges. Species here range from songbirds like blackbirds and robins, to mammals like the fox, badger and field mouse.
The Barrow is also very important for otters. Next time you are on your boat or walking along the Barrow Way Marked Way keep an eye out for these elusive graceful creatures. More often than not they will hear you and scamper away long before you see them. However the keen eye will pick up otter activity such as slides (a noticeable area of flattened grass/sediment where otters gain access to the water) or couches (prominent resting areas where faeces may also be visible).
Birds found along the navigation include moorhen and heron, as well as important populations of EU protected species such as kingfisher, bartailed godwit and peregrine. In a study carried out by Birdwatch Ireland in 2010, many other riparian birds were identified including kingfisher, teal, mallard, sand martin, grey wagtail, dipper, coot, sedge warbler, black-headed gull, mute swan and whooper swan. This survey was completed to quantify the distribution and densities of kingfisher and other waterways birds throughout six SAC river systems in Ireland. Kingfishers were encountered frequently along the River Barrow – the apparent proximity of kingfisher territories on the Barrow may be related to the shortage of suitable nesting banks elsewhere on the system. For more information on Irish birds visit www.birdwatchireland.ie
In addition to birds a number of Ireland’s bat species occur along the Barrow. In particular, species such as Daubenton’s Bat specificlly use the canal and river sections when foraging, flying close to the water’s surface and snatching insects mid flight.
The Barrow is an important natural and recreational mixed fishery. It is home to numerous species including salmon, brown trout and sea trout. Coarse fish species include bream, roach, rudd, pike, perch and tench. The River Barrow is one of the few rivers in Ireland that gets a run of twaite shad. These fish migrate into the tidal waters at St. Mullins to spawn during April and May.
Invasive species are unfortunately also present along the navigation. Waterways Ireland would urge boaters to be very careful to ensure these species are not spread. Of particular concern along the Barrow is Himalayan Balsam though other species such as Japanese Knotweed, Nuttall’s Pondweed, New Zealand Pygmyweed, Giant Hogweed and Dace are also present. The notorious Asian Clam is a most unwelcome recent addition to the fauna of Irish rivers and lakes. It was first discovered in Ireland in 2010 at St. Mullins and is now believed to be firmly established in the lower reaches of the River Barrow with staggering densities of up to 10,000 clams per square metre. Shockingly each clam can potentially produce 70,000 juveniles each year. The enormous potential for expansion has been confirmed as it was also recorded in the River Nore downstream of Inistioge and in the River Shannon at Banagher in 2011.
The Asian Clam is a major threat to Ireland’s habitats, native species and internationally renowned fisheries. The ecology of invaded watercourses can become dramatically altered and may become unsuitable for water-based amenity and recreational pursuits. Carpets of clams can clog the gravel beds in rivers and render them unavailable for spawning salmon, trout and sea lamprey. They will also displace invertebrates, including the protected freshwater pearl mussel.
Further information on invasive species along the Barrow can be found at www.caisie.ie or www.invasivespeciesireland.com
Immediately opposite the Garden of Remembrance in the centre of Leighlinbridge village are the Barrow Callows. Callow is a purely Irish word, largely unknown in the rest of the English speaking world and refers to the meadow land in the flood plain of a river that is normally under water in winter and dry in summer. An important habitat for winter migrant wildfowl and also for some species of summer migrant and resident birds, the Barrow Callows feature lapwing and curlew. Callows are also botanically important and contain many species of plant adapted to wet grassland that have become scarce elsewhere. The Barrow Callows contain flag irises, marsh marigolds, purple and yellow loosestrife and meadowsweet, amongst other such species. Part of the botanical wealth in the Barrow Callows results from the nutrient rich silt which the river deposits during the winter not only enriching the land but also removing potentially harmful nutrients from the water.