River Derwent SAC Conservation Objectives Supplementary Advice

European Site Conservation Objectives: Supplementary Advice on Conserving and Restoring Site Features River Derwent Special Area of Conservation (SAC) Site Code: UK0030253 Photo: the River Derwent at Kirkham Bridge Date of Publication: 27 March 2017 (version 2) Page 1 of 31 About this document This document provides Natural England’s supplementary advice about the European Site Conservation Objectives relating to the River Derwent SAC. This advice should therefore be read together with the SAC Conservation Objectives which are available here. You should use the Conservation Objectives, this Supplementary Advice and any case-specific advice given by Natural England, when developing, proposing or assessing an activity, plan or project that may affect this site. Any proposals or operations which may affect the site or its qualifying features should be designed so they do not adversely affect any of the attributes listed in the objectives and supplementary advice. This supplementary advice to the Conservation Objectives describes in more detail the range of ecological attributes on which the qualifying features will depend and which are most likely to contribute to a site’s overall integrity. It sets out minimum targets for each qualifying feature to achieve in order to meet the site’s objectives. The tables provided below bring together the findings of the best available scientific evidence relating to the site’s qualifying features, which may be updated or supplemented in further publications from Natural England and other sources. The local evidence used in preparing this supplementary advice has been cited. The references to the national evidence used are available on request. Where evidence and references have not been indicated, Natural England has applied ecological knowledge and expert judgement. You may decide to use other additional sources of information. In many cases, the attribute targets shown in the tables indicate whether the current objective is to ‘maintain’ or ‘restore’ the attribute. This is based on the best available information, including that gathered during monitoring of the feature’s current condition. As new information on feature condition becomes available, this will be added so that the advice remains up to date. The targets given for each attribute do not represent thresholds to assess the significance of any given impact in Habitats Regulations Assessments. You will need to assess this on a case-by-case basis using the most current information available. Some, but not all, of these attributes can also be used for regular monitoring of the actual condition of the designated features. The attributes selected for monitoring the features, and the standards used to assess their condition, are listed in separate monitoring documents, which will be available from Natural England. These tables do not give advice about SSSI features or other legally protected species which may also be present within the European Site. If you have any comments or queries about this Supplementary Advice document please contact your local Natural England adviser or email [email protected] Page 2 of 31 About this Site Name of European Site River Derwent Special Area of Conservation (SAC) Location East Riding of Yorkshire, North Yorkshire, York Site Maps The designated boundary of this site can be viewed here on the MAGIC website EU Site Code UK0030253 Designation Date April 2005 Qualifying Features See section below Designation Area 411.23 hectares Designation Changes n/a Feature Condition Status Condition assessment information relating to this site can be found using Natural England’s Designated Sites search tool. Names of component Sites of River Derwent SSSI Special Scientific Interest (SSSIs) Relationship with other The boundary of this SAC runs through, but is not included within, European or International Site the boundary of the Lower Derwent Valley SAC and Ramsar Site designations between its northern boundary at Newton Mask SSSI and its southern boundary at Breighton Meadows SSSI The boundary of this SAC is included within the Lower Derwent Valley SPA between its northern boundary at Newton Mask SSSI and its southern boundary at Breighton Meadows SSSI. Site background and geography Covering approximately 411.23 hectares, the 86.2 km length of the River Derwent SAC passes through four National Character Areas (NCAs) within Yorkshire, stretching from Ryemouth in the Vale of Pickering NCA to the north, downstream through the Howardian Hills, Vale of York and Humberhead Levels NCAs until its southern boundary at the confluence of the River Ouse. The River Derwent SAC represents one of the best British examples of the classic river profile, with its source in the high-energy upland valleys of the North York Moors whose energy dissipates as the channel becomes wider and deeper as it passes through the flat and wide lowland floodplain valleys to its confluence with the Ouse and out into the Humber Estuary. Only the lower reaches of the river are however designated SAC. The river supports an aquatic flora now uncommon in northern Britain. Several plant species, such as river water-dropwort Oenanthe fluviatilis, flowering rush Botumus umbellatus, shining pondweed Potamogeton lucens, arrowhead Sagittaria sagittifolia, opposite-leaved pondweed Groenlandia densa and narrow-leaved water-parsnip Berula erecta, are more typically found in lowland rivers in southern England. Page 3 of 31 The ‘Yorkshire Derwent’ is also noted for the rich diversity of its native fish communities, which include the Annex II species river lamprey Lampetra fluviatilis and sea lamprey Petromyzon marinus populations that spawn in the lower reaches, and bullhead Cottus gobio. The diversity of riparian habitats including wet woodland and fen also support a healthy population of otter Lutra lutra. About the qualifying features of the SAC The following section gives you additional, site-specific information about this SAC’s qualifying features. These are the natural habitats and/or species for which this SAC has been designated. Qualifying Habitats: • H3260 Water courses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation (‘Rivers with floating vegetation often dominated by water-crowfoot’) This habitat type is generally characterised by the abundance of water-crowfoots Ranunculus spp. Floating mats of these white-flowered species are characteristic of river channels in early to mid- summer. They may modify water flow, promote fine sediment deposition, and provide shelter and food for fish and invertebrate animals. Watercourses of this habitat type have a high degree of naturalness and are governed by dynamic processes which result in a mosaic of characteristic physical biotypes, including a range of substrate types, variations in flow, channel width and depth, in-channel and side-channel sedimentation features, bank profiles, erosion features and both in-channel and bankside vegetation cover. There are several variants of this habitat in the UK, depending on geology and river type, and at each site, the Ranunculus species will be associated with a different assemblage of other aquatic plants. The River Derwent SAC supports examples of water plants from the Ranunculion fluitantis and Callitricho-Batrachion vegetation (Rivers with floating vegetation often dominated by water-crowfoot). Submerged aquatic vegetation is varied and characterised by unbranched bur-reed (Sparganium emersum), fennel leaved pondweed (Potamogeton pectinatus), flowering rush (Butomus umbellatus), yellow water-lily (Nuphar lutea), and shining pondweed (Potamogeton lucens) with occasional arrowhead (Sagittaria sagittifolia), perfoliate pondweed (Potamogeton perfoliatus) and water crowfoot species (Batrachian Ranunculus spp.) Qualifying Species: • S1095 Sea lamprey Petromyzon marinus The sea lamprey Petromyzon marinus is a primitive, jawless fish resembling an eel. It occurs in estuaries and easily accessible rivers, and is an anadromous species (i.e. spawning in freshwater but completing its life cycle in the sea). The sea lamprey is the largest of the three species, reaching a size of approximately one metre in length. After spending 18-24 months feeding at sea, adult sea lampreys migrate into rivers during the spring and early summer. Like other species of lamprey, sea lampreys need clean gravel for spawning, and marginal silt or sand for the burrowing larvae following egg-hatching. They spawn between the months of May-July in areas of pebble and cobble substrate The River Derwent SAC is characteristic of the sea lamprey populations which inhabit the many rivers flowing into the Humber estuary in eastern England. The lower reaches of the Derwent provide the clean stable gravels needed for spawning and the stable silts with low flow and organic detritus for nursery habitat. Page 4 of 31 • S1099 River lamprey Lampetra fluviatilis The river lamprey Lampetra fluviatilis is found in coastal waters, estuaries and accessible rivers. The species is normally anadromous (i.e. spawning in freshwater but completing part of its life cycle in the sea), and pollution or artificial obstacles such as weirs or dams impede migration. The River Derwent SAC is one example of river lamprey populations which inhabit the many rivers flowing into the Humber estuary in eastern England. The lower reaches of the Derwent provide suitable areas of gravels, silt or sand for spawning. • S1163 Bullhead Cottus gobio The bullhead is a

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