Species Action Plan for Sussex
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6. Targets and Costs[top]
1. Undertake further survey work in order to develop a complete picture of the range and population densities of Mercuria confusa on the Arun by 2005.
2. Undertake ecological work at selected sites in order to ascertain in greater detail the habitat requirements and ecology of the snail by 2005.
3. Undertake surveys of appropriate stretches of the rivers Adur and Ouse to determine if further populations of the Mercuria confusa are present by 2005.
4. Establish a monitoring protocol and a suitable monitoring programme by 2002, and carry out monitoring on a biannual basis (ongoing, review every five years).
5. Ensure that M. confusa is included on the criteria and/or citations of all Arun valley SSSIs where the species is present.
6. Inform landowners and river banks managers of the presence of Mercuria confusa and seek to negotiate sympathetic physical management and/or suitable access for grazing animals. A paragraph about the snail should be included in each appropriate Environment Agency L.E.A.P.
7. Research the impact of boat traffic speed and density on populations of M. confusa and, in the light of findings, seek to ensure the development of a river-traffic regime that avoids damage to populations of the snail.
8. Inform the Environment Agency of the risks to M. confusa of any works that might disrupt the narrow salinity range or frequency of exposure to brackish waters required by the snail.
9. Produce a leaflet for land owners, conservation workers and the general public publicising the rarity and vulnerability of the snail and details the key features required for habitat management.
10. Undertake actions to raise funding to implement this SAP.
Survey work to be carried out by a consultant or invertebrate ecologist with experience of the species and requisite professional skills.
Survey of brackish pools south of Lyminster £400
Survey of marginal Phragmites and Glyceria north of Watersfield £400
Linear survey of the Arun corridor £1200
Environmental factors survey £1100
Surveys of potential sites on the Adur and Ouse for M. confusa £600
Total estimated budget to implement plan £4700
Opportunities for the species in Sussex:
Within the salinity range in the River Arun, Mercuria confusa has the potential to colonise all suitable upper tidal mud, especially where this is shielded by emergent vegetation such as Phragmites and Glyceria.
Limiting factors for the species in Sussex:
A number of factors could act to limit or reduce populations of Mercuria confusa in habitats adjacent to the River Arun. These include:
· An increase in boat traffic or maximum permissible traffic speeds;
· engineering works on the river bank or berm including the removal of mud or the deposition on these sites of sediments dredged from the river;
· barrage works altering the salinity range or flow regime of the river;
fencing of marginal fens that are currently open to grazing cattle.
8. Action Plan [top]
See Action Plan Table (on menu above)
This action plan will be monitored biannually as appropriate and reviewed every five years by the Sussex Biodiversity Partnership.
monitoring the distribution and population densities of the species in
Sussex will be carried out once a monitoring protocol has been established.
Abraham, F. & Willing, M. 1996, A short survey of the distribution and abundance of Pseudamnicola confusa at selected locations on the 'Burpham Loop' of the River Arun (August 1996), Unpublished report for the Environment Agency, Worthing.
Martin J. Willing, firstname.lastname@example.org
12. Appendix [top]