Floodplain Marsh, Reed Swamp, Reservoirs & Ponds

Floodplain Marsh & Reed Swamp

There are three key areas of reedbed and marsh in Hastings. The largest area occurs within Filsham Reedbed and within the adjacent Combe Haven Valley. Smaller areas also occur at the nearby Glyne Gap Marsh and South Saxons Wetlands. All three areas occur on the low lying alluvial deposits of clay, silt and sand within the floodplains of Combe Haven and Hollington Stream.

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These floodplains are fed by mineral rich groundwater and periodic flooding enriching the soil producing tall fen and marsh vegetation. In areas which are more permanently flooded with shallow water common reed Phragmites australis starts to dominate creating reedbed. Over time the reed litter builds up eventually becoming dry reedbed. Sallow and alder scrub then starts to dominate until the land eventually becomes wet woodland with high canopy. Marsh, fen and reedbed are ephemeral habitats due to this natural succession from shallow water to wet woodland and require a great deal of management to prevent losing their distinctive ecological components and the biodiversity associated with them.

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Filsham Reedbed is a complex mosaic of standing freshwater, ditches, marginal & aquatic vegetation, marsh, fen, scrub, wet woodland and reedbed. The reedbed is best known for the assemblage of breeding birds associated with reedbed and fen present at the site. This includes species such as bearded tit Panurus biarmicus, reed bunting Emberiza schoeniclus, reed warbler Acrocephalus scirpaceus and in recent years marsh harrier Circus aeruginosus.

Due to its coastal location the area is also an excellent site to observe migration with large numbers of migrants present during optimal weather conditions. Very large numbers of swallow Hirundo rustica, house martin Delichon urbicum, sand martin Riparia riparia and swift Apus apus sometimes feed over the reedbed during migration. Many rare migrants have also been recorded at Filsham Reedbed and the adjacent Combe Haven Valley.

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The reedbed and marsh is also used by many wintering birds most notably a large winter roost of pied wagtail and large numbers of wintering snipe Gallinago gallinago. Glyne Gap Marsh is one of the best places in Hastings to see wintering jack snipe Lymnocryptes minimus.

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Filsham Reedbed also supports a diverse invertebrate assemblage of species associated with reedbeds and wetland marginal vegetation. Recently the reed yellow-face bee Hylaeus pectoralis was found at Filsham. This highly specialised bee nests in the vacated galls of the fly Lipara lucens. The fly creates cigar shaped galls on the flower stems of common reed Phragmites australis. Once the fly has emerged the bees use the galls to create egg cells which are provisioned with pollen the bee ingests from flowers growing around the reedbed such as creeping thistle Cirsium arvense, common valerian Valeriana officinalis and hemp-agrimony Eupatorium cannabinum.

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Another wetland specialist bee that is common at Filsham is the yellow loosestrife bee Macropis europaea. This nationally scarce bee is unique in Britain as it provisions its nest with the fatty floral oils and pollen of yellow loosestrife Lysimachia vulgaris which grows in abundance at Filsham. The plant itself is unusual as it does not produce nectar so the bees have to forage for nectar on other flowers. At Filsham creeping thistle seems to be an important nectar source for this bee.

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Many rare and scare moths have been recorded at Filsham including dotted fan-foot Macrochilo cribrumalis, reed dagger Simyra albovenosa, rush wainscot Globia algae, water ermine Spilosoma urticae, and Webb’s wainscot Globia sparganii. The larvae of these moths feed on many of the wetland plants within the reedbed such as common reed Phragmites australis, reed-mace Typha latifolia, water mint Mentha aquatica, and yellow iris Iris pseudacorus.