Biodiversity & Conservation

To assess the sensitivity of the biotope, the sensitivity of component species is reviewed. Those species that are considered to be particularly indicative of the sensitivity of the biotope, and for which research has been undertaken in detail are shown below (see selection criteria). The biology of other component species of the biotope is also taken into account wherever information is known to the researcher.

• Phragmites australis
• Lamprothamnium papulosum
• Gasterosteus aculeatus
• Potamopyrgus jenkinsi
• Chara aspera
• Galium palustre
• Menyanthes trifoliata
• Equisetum fluiatile
• Carex rostrata
• Atriplex prostrata
• Puccinellia maritima
• Rhizedra lutosa
• Archanara geminipunctata
• Phragmataecia castaneae
• Photedes brevilinea
• Giraudiella inclusa
• Hyalopterus pruni
• Lasioptera arundinis
• Lipara lucens
• Lipara ruftitarsis
• Botaurus stellari
• Circus aeruginosus
• Circus cyaneus
• Grus grus
• Cettia cetti
• Locustella luscinioides
• Panurus biamicus
• Acrocephalus schoenobaenus
• Acrocephalus scirpceus
• Micromys minutus
• Agonium thoreyi
• Dromius longiceps
• Macroplea mutica
• Acrocephalus palundicola
• Arenostola phragmitidis

• Lamprothamnium papulosum
• Botaurus stellari
• Acrocephalus palundicola
• Cettia cetti
• Grus grus
• Locustella luscinioides
• Panurus biamicus
• Circus aeruginosus
• Phragmataecia castaneae
• Photedes brevilinea
• Dromius longiceps

Phragmites australis stabilizes the sediment, develops an organic sediment, provides a litter layer, and supports numerous species directly and indirectly, and provides primary productivity to the wider aquatic ecosystem. Amsberry et al. (2000) regarded the common reed as an 'ecosystem engineer'. Therefore, Phragmites australis has been chosen as the key structural species within the biotope. Grazers are probably important species in the food chain converting Phragmites australis and algal primary production to secondary production, directly available to their predators and to the wider community via the detrital food chain. In addition, their grazing activities probably control the growth of epiphytes that would otherwise shade or compete with the macrophytes. Hydrobia ulvae is included to represent gastropod grazers, while reference was made to Gammarus salinus and Gammarus insensibilis (the lagoon sand shrimp) to represent gammarid amphipod grazers. The mysid Neomysis integer has been used to represent the sensitivity of mysid species. Similarly, reference was made to Pomatoschistus minutus to represent the sensitivities gobies and other small fish.

The MNCR recorded only 20 species in a few records of the biotope but the biotope has been more extensively studied as the NVC S4 community. Rodwell (1995) described 4 sub-communities and 3 variants, including up to ca 40 species of vascular plants. Hawke & José (1996) reported that at least 700 species of invertebrates had been found associated with UK reed beds, of which 64 insects species were dependant on reed to some extent and 40 were entirely dependant, including 11 species of Lepidoptera whose larvae feed on reed (Fojt & Foster, 1992; Hawke & José, 1996). Arnold & Ormerod (1997) recorded 56 species of aquatic invertebrates in Phragmites reed swamps, most belonging to 1-6 families of Coleoptera, the Isopoda, Amphipoda or Gastropoda, with abundant Diptera (9 families). The species richness varies with salinity, habitat fragmentation (reed bed size), reed density, the abundant of litter, damage by the twin-spotted wainscot emergence regime, and management regime (Tscharnkte, 1992, 1999; Fojt & Foster, 1992; Hawke & José, 1996; Ditlhogo et al., 1992; Cowie et al., 1992; Arnold & Ormerod, 1997; Fell et al., 1997). Phragmites reed swamps are transitional communities between brackish water, saltmarsh and inland plant communities. Therefore, they are potentially species rich habitats inhabited by representatives of saline, brackish water and terrestrial macroinvertebrates, fish, amphibians, reptiles, birds and mammals. Lists of associated species are given by Haslam, 1972; Tscharnkte, 1992, 1999; Fojt & Foster, 1992; Hawke & José, 1996; Ditlhogo et al., 1992; Cowie et al., 1992; Arnold & Ormerod, 1997; Fell et al., 1997; and Müller, 1999). Reed beds support several species of conservation importance such as nationally or internationally rare moths and birds (see importance) (Fojt & Foster, 1992; Hawke & José, 1996).