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2008 BAP reporting -
Dolomedes plantarius (Fen Raft Spider)
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Summary
Please give a brief summary (3-4 sentences) of what you consider to be the
take-home messages from your report.
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The traditional focus of work has pretty much focused on Lopham & Redgrave fen, with only field survey work taking place at the other sites, and little effort made into consideration of establishing this species as a component of bigger wetland systems where it ought to reach the densities it has reached on sites such as Pevensey. A new direction is being sought at least in England to achieve this. The Welsh site remains relatively secure, though how widespread it is remains to be seen.
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Status
Please give your most accurate assessment of the status of your species or habitat for the UK and each country.
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Date assessed |
Value |
Units |
Accuracy |
Adequate baseline data? |
Data available via NBN? |
| UK |
2008 |
3 |
Site(s) / population(s) |
Sample or full survey |
No but likely by 2011 |
No |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No |
| E |
2008 |
2 |
Site(s) / population(s) |
Sample or full survey |
No but likely by 2011 |
No |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No |
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Pevensey levels and Lopham & Redgrave fen remain the classic English sites for this species, though a small and artificial pond site was recently discovered from Pevensey derived material. The Lopham population remains obstanantly small and stable, despite much work, and there is a need to review the Pevensey population since last it was counted. |
| NI |
Not relevant for this country |
| S |
Not relevant for this country |
| W |
2008 |
1 |
Site(s) / population(s) |
Partial survey |
Yes |
No |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No |
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A relatively newly discovered population in S Wales for this species. |
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Trend in biological status
Please give your best estimate of the current trend for your species or habitat for the UK, and each appropriate country.
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Date assessed |
Trend |
Accuracy |
Adequate baseline data? |
Data available via NBN? |
| UK |
2008 |
Fluctuating - probably stable |
Partial survey |
No but likely by 2011 |
No |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No |
| E |
2008 |
Fluctuating - probably stable |
Partial survey |
No but likely by 2011 |
No |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No |
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The Lopham Population has suggested a range extension in the face of better grazing of the fen vegetation, whilst the Pevensey population was quite large in the last survey. It is considered, in combination, that this is probably a stable English population, in the light of the number of agi-environment agreements on the Pevensey levels, though these are not specifically ditch-focused. An analysis of a smaple of nursery webs between 1990 and 1991 should not statisticaly significant differences, |
| NI |
Not relevant for this country |
| S |
Not relevant for this country |
| W |
2008 |
Fluctuating - probably stable |
Best guess |
No but likely by 2011 |
No |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No |
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Asides from establishng its presence it is not considered that the full extent of Dolomedes occupation across Crymlyn Bog and asspciated and connected wetlands is fully known. This is, in part, becuase of the extreme difficulty of surveying in this terrain, and the difficuty, (despite its size) of seeing Dolomedes in situ. It is considered that the habitat is probably good enough at present for the spider not to be declining. |
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State of knowledge
To what extent is our scientific knowledge of the habitat / species (e.g research information, autecological knowledge, knowledge for effective re-introduction or habitat restoration / re-creation) sufficient to deliver the plan targets?
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| Status of knowledge |
Notes |
| Knowledge sufficient to make some impact, but more research needed |
The years of research at Lopham & Redgrave Fen have given us much information on trhe habitat preferences of this large and striking spider. One of the remaining gaps in information is the protocol for rearing spiderlings as part of any recovery programme. This is being addressed as of 2008.
As part of the consideration of adding the species to new sites, new volunteer field survey is proposed in the coming years to see if morwe populations are already present in the many wetlands available for potential re-introduction. The threat at pevensey from Hydrocotyle invasion of some of the ditches has an unknown impact on the spider, and should be investigated. |
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Progress on targets
For each of the plan targets please give a qualitative assessment of progress for the UK and each country.
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T1
Increase the overall range of the fen raft spider at Redgrave & Lopham Fen to 13 Ha of habitat occupied 3 years in 5 by 2010 and to 65 Ha by 2020.
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Target type |
Range |
Units |
Hectares |
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2010 target |
Current value |
Status |
Date assessed |
Accuracy of estimate |
UK |
13 |
5.1 |
Some progress (on schedule) |
2008 |
Sample or full survey |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No
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E |
13 |
5.1 |
Some progress (on schedule) |
2008 |
Sample or full survey |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No
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NI |
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This target has been flagged as not applicable for this country |
S |
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This target has been flagged as not applicable for this country |
W |
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This target has been flagged as not applicable for this country |
Comments |
In reality a target revision of 7ha is more than likely. It has been suggested that a 2020 target of c. 25ha and 2015 target of 10ha is more relevent, given the current
positive changes in vegetation on the site, the general immobility of the spiders, and the likelihood of one or two translocations within site
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T2
There should be no overall decrease in occupied range of fen raft spider at Pevensey Levels from that recorded in 1990 at any time.
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Target type |
Range |
Units |
Occupied 1 km squares |
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2010 target |
Current value |
Status |
Date assessed |
Accuracy of estimate |
UK |
9 |
9 |
Target achieved |
2008 |
Sample or full survey |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No
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E |
9 |
9 |
Target achieved |
2008 |
Sample or full survey |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No
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NI |
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This target has been flagged as not applicable for this country |
S |
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This target has been flagged as not applicable for this country |
W |
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This target has been flagged as not applicable for this country |
Comments |
The answer to this target requires a new and comprehensive field survey of the Pevensey levels which has yet to be carried out, but which will use the early 1990 survey as the baseline. Other outliers arer bel;ived to have been found, so increasing this coverage, but the whole thing needs a review.
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T3
The number of sites with sustainable populations of fen raft spider should be increased by six by 2010. By 2020 the total number of sites with sustainable populations should be increased to 12.
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Target type |
Range |
Units |
Site(s) / population(s) |
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2010 target |
Current value |
Status |
Date assessed |
Accuracy of estimate |
UK |
6 |
3 |
Some progress (behind schedule) |
2008 |
Sample or full survey |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No
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E |
4 |
2 |
Some progress (behind schedule) |
2008 |
Sample or full survey |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No
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NI |
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This target has been flagged as not applicable for this country |
S |
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This target has been flagged as not applicable for this country |
W |
2 |
1 |
No progress |
2008 |
Best guess |
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Did you refer to the LBAP data (e.g. obtained from the links provided) when compiling this assessment? No
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Comments |
A list of likely receptor sites is being worked on as part of a renewed direction of the SRP in England, linked in with bulking up a population of spiders to introduce. This work will be achieved through a partnership of interested bodies and land holders. It is not known if a similar excercise has been adopted in S wales yet, though the combination of sites used there might lead one to state that it might already be on more than "one site".
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Current or emerging threats
Please list the factors which, in the steering group's opinion, currently or are likely to pose a significant threat to the species / habitat over the next 5 years.
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| Threat category 1 |
Threat category 2 |
England |
Northern Ireland |
Scotland |
Wales |
| Invasive/non-native species |
Habitat degradation |
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Constraints
Please identify the main obstacles (constraints) to achieving BAP targets, and the solutions for overcoming them.
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There are no significant constraints to meeting the plan targets for this national plan.
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Successes
Since 2005, have there been key successes in the implementation of your plan that should be drawn to the attention of government, the wider BAP partnership, or the public?
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| Success category 1 |
Success category 2 |
England |
Northern Ireland |
Scotland |
Wales |
| Action plan process |
Work plan established |
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Summary: |
A new work plan with funding has been established to re-focus on establishing new populations of this spider, if suitable sites can be found.
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| Funding and incentives |
Species recovery programme - delivering wildlife gains |
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Summary: |
Part of this programmeis core funding current work.
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| Partnership |
Research institutions - engaged |
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Summary: |
Recent agreement with the John Innes Centre on developing the protocols for rearing Dolomedes spiderlings has just started. Also some interest in genetics from Nottingham University.
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| Partnership |
Voluntary / charitable body involvement |
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Summary: |
Work with BAS members
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| Research, survey and information |
Baseline survey - achieved or started |
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Summary: |
The "new" Welsh population has been recognised, but more work is needed to ascertain the true extent of occupation.
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| Species and habitat management |
Grazing regime improvement |
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Summary: |
Grazing regimes have improved on Lopham & redgrave Fen
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