Contents. 1. Introduction 3 2. Saltmarsh in Halton 4 3. Survey 5 4. Results 6 5. Conclusion 11

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2 Contents 1. Introduction 3 2. Saltmarsh in Halton 4 3. Survey 5 4. Results 6 5. Conclusion 11 2

3 1. Introduction A saltmarsh occurs between the mean high water level of neap tides and the mean high water level of high tides, where net deposition of sediment is occurring. In simpler terms, this means that in tidal areas a saltmarsh will be found between the average level low tides and the average level of the high tides. Below this level the land is inundated too often for saltmarsh species to get established, and above this level the land is dominated by the usual terrestrial species. The main criterion that enables saltmarsh to exist as a distinctive habitat is inundation from saline water, which is usually the sea or an estuary. These conditions provide a habitat that only species with species adaptations can survive and prevent the standard suite of terrestrial flora from establishing themselves. A saltmarsh won t occur in every tidal zone, as net accumulation of sediment is required. Net accumulation of sediment is a process where by more sediment is deposited than washed away, thus providing a substrate for the saltmarsh species to grow in. The type of sediment can affect the make up of the marsh, as can other physical factors such as the steepness of the marsh or the presence of freshwater streams. A sheltered position is also usually required for a saltmarsh to exist, to allow for the necessary accumulation of sediments. The variability of the physical factors mean that the vegetation communities can vary across different sites, but also within the same site. Perhaps the most important factor is tidal variability. The vegetation of a saltmarsh can be vastly different in most regularly inundated areas from those areas that are less regularly inundated. In fact, most saltmarshes can be divided into distinctive zones with a distinct suite of flora depending on the amount of tidal inundation. Usually towards to lower end of the marsh, where the tide intrudes as often as daily or pioneer species such as the glassworts (Salicornia sp., Sarcocornia sp.), cord grasses (Spartina sp.) annual sea-bite (Suaeda maritima), and asters (Aster sp.). This community is known as the pioneer community. Further up the marsh, where the tide reaches less often, there is a different selection of plants. These areas are characterised by saltmarsh grass (Puccinellia maritime), red fescue (Festuca rubra), sea rush (Juncus maritima) and saltmarsh flat-sedge (Blysmus rufus). These species do not have to cope with very salty conditions very often, but may be submerged every so often by a very high tide. In some areas, further diversity may be brought to the plant communities by the presence of fresh water making its way down to the coast. Not only is there variation within the saltmarsh, but there is also variation between marshes caused by the physical conditions of the locality, such as the amount of shelter from surrounding land formations. In Halton, the saltmarsh is described as estuarine as it is formed in the tidal zones of the river Mersey. Estuarine saltmarshes are characterised by the interactions between freshwater from the river and saline water from the tide. This can create a range different habitat types which would not be found in the other types of saltmarsh such as brackish reedbeds. Saltmarsh is a habitat that has undergone significant decline in Britain for a number of reasons. Perhaps the most significant historical reason for the reduction in saltmarsh 3

4 area has been land reclamation for agriculture through draining, a processes that has stabilised naturally changing coastal landscapes. Under natural conditions areas of saltmarsh will constantly be eroded by wave action, but be replaced in other areas by accretion of sediment. Human attempts to stabilise the coast for agriculture have altered this natural process and caused a net loss of in the area of saltmarsh. The remaining stabilised areas have often been grazed very heavily, reducing their value as habitats. Another major factor causing saltmarsh reduction is the building of hard coastal defences and general concrete constructions adjacent to the sea. Structures such as groins can reduce the mobility of sediment and prevent the build-up of saltmarsh in other areas. Where there are hard constructions adjacent to a saltmarsh (e.g. roads and houses etc.), natural erosion of that marsh will cause a net loss of marsh area as the construction prevents new marsh being created further inland. This process is called coastal squeeze and is most commonly used to describe the problems exacerbated by sea level rise. Sea level rise is becoming an increasing problem for saltmarshes as the climate changes and the volume of the oceans increases. Under purely natural conditions the position of saltmarshes would be flexible, as deposition, erosion and sea level rise destroy and create new areas of suitable habitat. However, on built up coastlines these processes are interrupted and saltmarshes are eroded or submerged as the sea level increases and hard coastal defences prevent the creation of new marsh. Other than physical factors, saltmarshes are under threat from invasion by foreign species. The common cord-grass (Spartina anglica) is a hybrid between the native small cord-grass (Spartina maritima) and the American smooth cord-grass (Spartina alterniflora). It was thought that this species was first produced around the Southampton area and it has now spread to colonise many areas of saltmarsh. This is a problem because the aggressive competitive nature of the species means it has taken over areas formerly colonised by the native small cord-grass and thus reducing the overall population of small cord-grass. Common cord-grass also tends to reduce the overall species diversity of a marsh by reducing the opportunity for other plant species to take a hold, especially the pioneer species. Common cord-grass is not just a problem for other plant species, but for birds as well. Many birds such as waders and wildfowl rely on saltmarshes to provide them with feeding grounds, especially in the winter when large migrations arrive on British coasts and estuaries. On marshes that have been severely affected by the common cord-grass, many of the habitats and sub-habitats that provide invertebrate food for the birds are no longer available. 2. Saltmarsh in Halton In Halton the areas of saltmarsh flank the Mersey estuary on the north and south banks and are therefore classified as estuarine saltmarsh. These areas are home to a range of species many of which are under threat. The redshank for example will feed on the estuary mudflats and the saltmarsh in the winter, when large numbers of birds come down from the far north. In summer, the saltmarsh grasses proved ideal nesting habitat for the redshank, which will feed in the in occasional shallow pools that have 4

5 formed amongst the vegetation, known as scrapes. Other sensitive species that breed in the saltmarsh included the skylark, which is a species that has suffered greatly during the 20 th century. These birds require large open swathes of relatively low growing vegetation and Halton s saltmarsh provides just such as habitat. In order to promote and assist the conservation of the saltmarsh, Halton Borough Council has produced a Habitat Action Plan (HAP). This plan outlines key actions in order to safe-guard the extent and quality this sensitive habitat. Key actions in the HAP include; Off-setting habitat loss with creation of new habitat Promoting management strategies sympathetic to high species diversity Raising public awareness Continued surveying and recording It is the final action listed here that record are involved in. record have been tasked with keeping the existing records for the saltmarsh areas as well as undertaking new surveys in order to inventory and monitor the change of the saltmarsh. 3. Survey record were commissioned to carryout a botanical survey. This was done using the expertise of an experienced botanist. It was decided to survey two areas on the south bank of the estuary to see if there were any noticeable differences. Relative abundance was recorded along side the species and its location. Figure 1 (below) is a map showing the areas in question. Figure 1. Map showing the position of saltmarshes covered by this survey 5

6 Two days work were spent surveying the sites, Upper Moss Side Farm first, then Astmoor Saltmarsh on Monday 30 th July and Wednesday 2 nd August. 4. Results Survey results for Upper Mosside Farm were all new as there were no previously held records. Astmoor Saltmarsh was already a well recorded site, yet surveying still returned records of 47 new species. A full list of species is contained in tables 1 and 2 (below). It is worth noting that these lists include the immediate environs of the areas in question and may include species that are not normally found on the Saltmarsh. In these cases, it is likely that the species in question (e.g. Field maple) is situated in the upper area of the site, as the saltmarsh turns into the more usual terrestrial habitat. Table 1. Details of all the botanical species for Astmoor Saltmarsh held on the record database. Scientific Name English Name New Record Produced From Survey Acer campestre Field maple Acer platanoides Norway maple Yes Achillea millefolium Yarrow Aethusa cynapium Fool's Parsley Agrostis canina sens.lat. Velvet Bent Agrostis stolonifera Creeping Bent Yes Alliaria petiolata Garlic Mustard Alnus glutinosa Alder Alnus incana Grey Alder Yes Alopecurus geniculatus Marsh Foxtail Yes Anagallis arvensis Scarlet Pimpernel Angelica archangelica Garden Angelica Angelica sylvestris Wild Angelica Apium graveolens Wild Celery Armoracia rusticana Horse-Radish Arrhenatherum elatius Arrhenatherum elatius Artemisia vulgaris Mugwort Aster tripolium Sea Aster Atriplex littoralis Atriplex littoralis Yes Atriplex prostrata Spear-Leaved Orache Bellis perennis Daisy Yes Betula pendula Silver Birch Bidens tripartita Trifid Bur-Marigold Blackstonia perfoliata Yellow-Wort Bolboschoenus maritimus Sea Club-Rush Brassica nigra Black Mustard Yes Brassica rapa Turnip Yes Buddleja davidii Buddleja Yes Callitriche stagnalis sens.lat. Common Water-Starwort Calystegia sepium Hedge Bindweed Calystegia sepium roseata Bindweed Yes Calystegia sepium sepium Great Bindweed Yes 6

7 Calystegia silvatica Large Bindweed Calystegia silvatica disjuncta Large Bindweed Yes Calystegia soldanella Sea Bindweed Capsella bursa-pastoris Shepherd's-Purse Carex hirta Hairy Sedge Carex otrubae False Fox-Sedge Carex riparia Great Pond-Sedge Centaurea nigra Centaurea nigra Centaurium erythraea Centaurium erythraea Centaurium littorale Seaside Centaury Cerastium fontanum Common Mouse-Ear Chamerion angustifolium Rosebay Willowherb Cirsium arvense Creeping Thistle Cirsium palustre Marsh Thistle Cirsium vulgare Spear Thistle Cochlearia anglica English Scurvygrass Convolvulus arvensis Field Bindweed Conyza canadensis Canadian Fleabane Yes Corylus avellana Hazel Crataegus laevigata Midland Hawthorn Crataegus monogyna Hawthorn Crepis capillaris Smooth Hawk's-Beard Crepis vesicaria Beaked Hawk's-Beard Cytisus scoparius Broom Dactylis glomerata Cock's Foot Daucus carota Wild Carrot Deschampsia caespitosa Tufted Hair-Grass Yes Deschampsia caespitosa caespitosa Tufted Hair-Grass Yes Digitalis purpurea Foxglove Dipsacus fullonum sens.lat. Wild Teasel Dryopteris dilatata Broad Buckler-Fern Yes Duchesnea indica Yellow-Flowered Strawberry Eleocharis palustris Common Spike-Rush Elymus canadensis Couch Elytrigia atherica Sea Couch Elytrigia repens Common Couch Yes Epilobium ciliatum American Willowherb Yes Epilobium hirsutum Great Willowherb Epilobium palustre Marsh Willowherb Epilobium parviflorum Hoary Willowherb Yes Epilobium x interjectum Hybrid Willowherb Yes Epilobium x novae-civitatis Hybrid Willowherb Yes Equisetum arvense Field Horsetail Eupatorium cannabinum Hemp-Agrimony Fallopia japonica Japanese Knotweed Yes Festuca arundinacea Tall Fescue Yes Festuca rubra agg. Red Fescue Filipendula ulmaria Meadowsweet Fraxinus excelsior Ash 7

8 Fumaria muralis boraei Few-Flowered Fumitory Yes Galium aparine Cleavers Yes Geranium dissectum Cut-Leaved Crane's-Bill Geranium pusillum Small-Flowered Crane's- Yes Bill Glaux maritima Sea-Milkwort Hieracium agg. Hawkweed Yes Hippophae rhamnoides Sea-Buckthorn Holcus lanatus Yorkshire Fog Hypericum perforatum Perforate St John's Wort Hypochaeris radicata Cat's-Ear Yes Impatiens glandulifera Himalayan Balsam Juncus acutus Sharp Rush Juncus effusus Soft Rush Yes Juncus inflexus Hard Rush Lactuca serriola Prickly Lettuce Yes Lapsana communis Nipplewort Lathyrus nissolia Grass Vetchling Lathyrus pratensis Meadow Vetchling Leontodon saxatilis Lesser Hawkbit Yes Leucanthemum vulgare Oxeye Daisy Lotus corniculatus Common Bird's-Foot- Trefoil Lycopus europaeus Gipsywort Medicago lupulina Black Medick Melilotus altissimus Tall Melilot Yes Odontites vernus Red Bartsia Yes Oenanthe crocata Hemlock Water- Dropwort Ophrys apifera Bee Orchid Papaver rhoeas Common Poppy Persicaria amphibia Amphibious Bistort Yes Phalaris arundinacea Reed Canary-Grass Phragmites australis Common Reed Plantago major Greater Plantain Plantago maritima Sea Plantain Poa annua Annual Meadow-Grass Polygonum aviculare sens.str. Knotgrass Populus alba White Poplar Populus tremula Aspen Potamogeton pectinatus Fennel Pondweed Yes Potentilla anserina Silverweed Primula veris Cowslip Prunella vulgaris Selfheal Prunus avium Wild Cherry Yes Prunus spinosa Blackthorn Pteridium aquilinum Bracken Puccinellia maritima Common Saltmarsh- Grass Pulicaria dysenterica Common Fleabane 8

9 Quercus robur Common Oak Ranunculus repens Creeping Buttercup Ranunculus sceleratus Celery-Leaved Buttercup Raphanus raphanistrum Wild Radish Reseda lutea Wild Mignonette Reseda luteola Weld Rosa canina agg. Dog Rose Rosa rubiginosa agg. Sweet-Briar Yes Rubus armeniacus Bramble Yes Rubus fruticosus agg. Bramble Rumex acetosella acetosella Sheep's Sorrel Rumex crispus Curled Dock Rumex crispus littoreus Curled Dock Yes Rumex hydrolapathum Water Dock Rumex obtusifolius Broad-Leaved Dock Salicornia aggregate Glasswort Yes Salicornia europaea agg. Glasswort Salix cinerea Grey Willow Salix fragilis Crack Willow Sambucus nigra Elder Schoenoplectus lacustris Common Club-Rush Schoenoplectus tabernaemontani Grey Club-Rush Scrophularia nodosa Common Figwort Yes Scutellaria galericulata Skullcap Senecio jacobaea Common Ragwort Senecio viscosus Sticky Groundsel Silybum marianum Milk Thistle Sonchus arvensis Perennial Sow-Thistle Yes Sonchus asper Prickly Sow-Thistle Sonchus oleraceus Smooth Sow-Thistle Sorbus aria agg. Whitebeam Sorbus aucuparia Rowan Sorbus intermedia Swedish Whitebeam Yes Spartina anglica Common Cord-Grass Yes Spergularia marina Lesser Sea-Spurrey Stachys palustris Marsh Woundwort Stellaria media agg. Chickweed Suaeda maritima Annual Sea-Blite Yes Taraxacum officinale agg. Dandelion Torilis japonica Upright Hedge-Parsley Yes Tragopogon pratensis Goat's-Beard Trifolium dubium Lesser Trefoil Yes Trifolium pratense Red Clover Trifolium repens White Clover Triglochin palustre Marsh Arrowgrass Tripleurospermum maritimum agg. Mayweed Tussilago farfara Colt's-Foot Typha angustifolia Lesser Bulrush Typha latifolia Bulrush Ulmus glabra Wych Elm 9

10 Urtica dioica Verbascum thapsus Vicia cracca Vicia hirsuta Vicia tetrasperma Viola arvensis Stinging Nettle Great Mullein Tufted Vetch Hairy Tare Smooth Tare Field Pansy Perhaps unsurprisingly most of the species found at Upper Mosside Farm are also found at Astmoor. However, this is not true for all species and this information is contained within table 2. Table 2. Details of species recorded from Upper Mosside Farm. Unless otherwise stated, there are records of each species at Astmoor Saltmarsh. Species English Name Also at Astmoor Agrostis stolonifera Creeping Bent Alopecurus geniculatus Marsh Foxtail Angelica sylvestris Wild Angelica Apium graveolens Wild Celery Arctium minus Lesser Burdock No Arrhenatherum elatius False Oat-Grass Artemisia vulgaris Mugwort Atriplex glabriuscula Babington's Orache No Atriplex prostrata Spear-Leaved Orache Avena fatua Wild Oat No Bolboschoenus maritimus Sea Club-Rush Brassica rapa Turnip Calystegia sepium roseata Bindweed Cirsium arvense Creeping Thistle Cirsium vulgare Spear Thistle Cochlearia anglica English Scurvygrass Crataegus monogyna Hawthorn Dactylis glomerata Dactylis glomerata Elytrigia repens Common Couch Epilobium hirsutum Great Willowherb Epilobium obscurum Short-Fruited Willowherb No Epilobium parviflorum Hoary Willowherb Festuca arundinacea Tall Fescue Galeopsis bifida Bifid Hemp-Nettle No Galium aparine Cleavers Geranium dissectum Cut-Leaved Crane's-Bill Glaux maritima Sea-Milkwort Helianthus annuus Sunflower No Lactuca serriola Prickly Lettuce Lolium perenne Perennial Rye-Grass No Matricaria recutita Scented Mayweed No Oenanthe crocata Hemlock Water-Dropwort Persicaria amphibia Amphibious bistort Phalaris arundinacea Reed Canary-Grass Phragmites australis Common Reed 10

11 Plantago lanceolata Ribwort Plantain No Polygonum aviculare Knotgrass No Prunus avium Wild Cherry Puccinellia distans Reflexed Saltmarsh-Grass No Puccinellia maritima Common Saltmarsh-Grass Rubus fruticosus agg. Bramble Rumex crispus littoreus Curled Dock No Rumex obtusifolius Broad-Leaved Dock Sambucus nigra Elder Senecio vulgaris Groundsel No Sonchus arvensis Perennial Sow-Thistle Sonchus asper Prickly Sow-Thistle Spartina anglica Common Cord-Grass Spergularia marina Lesser Sea-Spurrey Stachys palustris Marsh Woundwort Taraxacum officinale agg. Dandelion Tripleurospermum inodorum Scentless Mayweed No Tripleurospermum maritimum Sea Mayweed No Urtica dioica Stinging Nettle 5. Conclusions One of the most noticeable and controversial records is of Seaside Centaury Centaurium littorale. This species is not widespread (although it is not thought to be under threat currently), but it is thought by some that this record is anomalous and the survey of Astmoor raised no new records of this species. The fact that this species was recorded anomalously adds further suspicion to the record, which is also the only record on the database. Local botanists claim that not since the 19 th century has Seaside Centaury actually been seen in Cheshire. One nationally scarce plant that was recorded was the bindweed Calystegia sepium roseate (pictured below) which was found in both areas of survey. This was a new discovery as there were no previous records for it. This species is referred to in the rare plant register for Cheshire as Seaside Hedge Bindweed and was recorded as being frequent during this survey. The population of this species around the river Mersey is largest in the Cheshire region. 11

12 Figure 1. Calystegia sepium roseata Finally the presence of Common Cord Grass Spartina Anglica is worthy of note. Currently it has only been recorded as rare at both sites, but continued monitoring of the area is required to keep it in check and to make sure that it is not having a detrimental effect on the conservation value of Halton s saltmarshes. Further and regular recording activity is also required to keep track of the population of the Seaside Hedge Bindweed and make sure the addition/re-introduction of important species like Seaside Centaury is not missed. 12