Waterways and Wildlife Managing Our Natural Environment Contents
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Waterways and Wildlife Managing our natural environment Contents Preface 4 Habitats Chapter 1 Navigable channels 5 Chapter 2 Waterway banks and grasslands 11 Chapter 3 Hedgerows 17 Chapter 4 Trees, woodland and scrub 23 Chapter 5 Built structures 29 Chapter 6 Other waters 35 Wildlife Chapter 7 Water plants 41 Chapter 8 Aquatic invertebrates 47 Chapter 9 Fish 53 Chapter 10 Amphibians and reptiles 59 Chapter 11 Pollinators 65 Chapter 12 Water voles and otters 71 Chapter 13 Bats 77 Chapter 14 Birds 83 2 www.canalrivertrust.org.uk Waterways and Wildlife handbook 3 Preface Navigable Most people visiting our waterways, including walkers, We hope that anyone with an interest in canals, channels cyclists and boaters, are attracted to the towpaths and waterways and their wildlife will find this handbook navigations because of their beauty and tranquillity. informative and useful. Our aim is to give an insight For many, an integral part of the waterway experience into the wide range of habitats and wildlife that we Navigable channels are the heart of the waterway is the rich diversity of wildlife encountered here, and care for, and to highlight some of the many ways in system, around which all the other habitats and this diversity is an essential part of a healthy waterway which we manage our natural environment to make a wildlife interest have developed. The channels are ecosystem. From hidden underwater wildlife to the difference. The handbook has six chapters on habitats not only important for biodiversity in their own right, brilliant blue of a kingfisher, and the quintessential and eight chapters on wildlife groups. Each chapter they act as continuous habitat corridors through sight and sound of dragonflies to the glimpse of a bat summarises key information on each habitat / wildlife the landscape, linking other aquatic and terrestrial foraging over the water at dusk, our waterways are group, has two short feature articles on a selection features, increasing their value for wildlife. Since enjoyed for their unique and treasured biodiversity. of the Trust’s work in this area, and concludes with a their construction around 200 years ago, navigable list of example management actions. The handbook waterways have been colonised by a rich variety of Many waterside habitats have become fragmented or is a first step in delivering a vision for the role that the plant and animal life. Their slow flows and managed have vanished from the countryside entirely, making natural environment of the canals of Wales can and water levels provide a unique habitat and many are waterways especially valuable habitats and much- does play within the wider landscape; the principles designated as important nature sites. We manage our needed corridors for wildlife. For some species, our are applicable to all our waterways and it is our hope navigable channels to enhance their wildlife interest, waterways are among their last remaining strongholds that we will be in the vanguard of change across and aiming to create an environment that works for today’s and, for many others, they provide vital resources now beyond Wales. users of the waterways as well as for wildlife. scarce in the wider countryside. Canals are probably the most familiar waterbodies, but the Canal & River This handbook has been developed by Glandwˆr Key points Trust also has many reservoirs, lakes and ponds, Cymru (the Canal & River Trust in Wales) in hedgerows and trees to look after. Canal hedgerows, collaboration with Ruth Feber at the Wildlife • Navigable channels are the heart for example, are some of our oldest waterway features Conservation Research Unit (WildCRU), University of the waterway system and lifelines for many species, providing food, shelter of Oxford. We are grateful to the Welsh Government • Slow flows and managed water levels and places to breed. Our many built structures, for funding this work, through the Green Infrastructure for boats create a unique environment including aqueducts and bridges, play an important, Capital Investment fund. We hope that this handbook for a diversity of species but often overlooked, role as wildlife homes, especially will inspire and be of use to all those who own, manage, because of their proximity to water. With the variety of work on or simply enjoy our canals and waterways. • We need to balance the needs of people and waterway habitats on our estate, work is needed to wildlife when managing these channels maintain and enhance their biodiversity value, while at the same time ensuring that our navigations and towpaths can be enjoyed safely. It is our aim to achieve a balance that works for both people and wildlife. Monmouthshire and Brecon Canal 4 www.canalrivertrust.org.uk Waterways and Wildlife handbook 5 Wildlife Channel management Navigable waterways were originally built to move Active management of waterway channels and freight, but they have long had nature conservation adjoining vegetation, like trees, is needed not only value. With the loss of water and wetland habitats in to keep them navigable and safe for people, but the countryside, the value of navigable channels and also to maintain their wildlife value. Because of their waterside habitats has increased greatly. Some slow flows and controlled water levels, open water channels harbour remnant populations of rare species would eventually be lost to encroaching vegetation, and the importance of these sites is recognised at so regular weed cutting or dredging of channels national or international levels. Other navigable is carried out. Dredging removes silt and sediment channels may have less biodiversity value, but can still accumulations, including polluted ones. A range of provide important habitats for wildlife, in both urban pollutants, from industrial spillages, boat fuel spills and rural areas. and bilge water, to sewage effluents and diffuse agricultural pollutants, can end up in the water. The value of waterway channels for wildlife is Pollutants are harmful to aquatic life and lead to loss determined by several factors, particularly water of biodiversity; tackling pollution is an important part quality, boat traffic, and bank and channel structure. of our work. Common blue damselfly The richest channel biodiversity is generally found Tree fallen across the channel blocking the where water quality is high, boat traffic is low, and Dredging and weed cutting cause disruption in the navigation, in need of removal where banks and channels are natural rather than short term, but most communities recover and the highly modified structures with hard, steel sheet piled, habitat is kept suitable for early successional species or wholly concrete, banks. Natural and engineered that would otherwise be crowded out. These include soft banks support a rich abundance of aquatic important species such as the floating water plantain plants, providing habitat for many species of on the Montgomery Canal, which cannot compete invertebrates and fish, and, in turn, animals higher up with more robust species. Whenever channel the food chain, such as otters and kingfishers. Some management is carried out, care is taken to leave the hold important populations of scarce plants, insects banks, and a specified minimum band of reed fringe and molluscs. alongside it, as undisturbed as possible. The deeper central areas of the channel are generally For wildlife of the navigable channel, boat traffic poorer in invertebrate diversity compared to the can cause problems. This is particularly true for shallow margins. In the margins there are more plants submerged plant species, which can be damaged that provide shelter, and dragonflies, water beetles, by boats, while delicate bankside plants and animals water bugs and snails can be found here. Generally, can be affected by waves and boat wash. If there is a the more species-rich and abundant the vegetation, lot of sediment and algae in the water it can smother the richer the community of invertebrates. All channels not only water plants, but also invertebrates and fish support populations of fish, dominated by coarse fish eggs within the channel. In general, less boat use is such as carp, perch and roach. Some waterways associated with higher biodiversity but, nonetheless, Mallards Our specialised fisheries contractor removing the provide an important habitat for eels, who like plenty channels with heavy boat traffic still support species non-native invasive zander of muddy sediment in which to scavenge for their prey that are tolerant of disturbance. and hide, down in the depths of the channel. Being highly connected, the waterway channel is easily colonised not only by native species, which is desirable, but non-native ones too. These invaders can be very difficult to control. Plants such as floating pennywort form thick mats of vegetation across the channel, shading out light for species below. A notorious invertebrate invader is the American signal crayfish, which has out-competed our native white- clawed crayfish. Invasive fish, too, can upset the ecological balance – zander, for example, is prevalent in turbid channels and is a voracious predator. Roach are the most common fish of the waterway Dredging to remove sediment from the channel channels 6 www.canalrivertrust.org.uk Waterways and Wildlife handbook 7 Volunteer marking up a surface water drain with the Yellow Fish logo Azolla starting to invade the channel next to the bank Making a difference: 1 Making a difference: 2 Only rain down the drain! Weevil army eats canal menace Good water quality is vital for waterway wildlife. For Highlights Canals are the super slow-ways of our beautiful blue Highlights example, drains with contaminated surface water, and green nation, but they are vulnerable to invasions • Good water quality is needed to support • Like many invasive water plants, Azolla is a misconnected pipes from toilets or dishwashers and from non-native species that take advantage of the a variety of wildlife and plants garden escapee sold for use in ponds, but improper use of industrial site drainage all have a connections across the landscape.