Coastal lagoon habitat re-creation potential in Hampshire, England

ARTICLE IN PRESS

Marine Policy 31 (2007) 599–606 www.elsevier.com/locate/marpol

Coastal lagoon habitat re-creation potential in Hampshire, England D.E. Johnson, J. Bartlett, L.A. Nash Faculty of Technology, Southampton Solent University, East Park Terrace, Southampton SO14 0YN, UK

Abstract The Solent region in southern England represents one of the highest concentrations of coastal lagoons and saline ponds in the UK. Four lagoon complexes within the region comprise a Special Area of Conservation (SAC), under the European Habitats Directive. The ephemeral nature of coastal lagoons presents a particular management challenge in terms of retaining designated sites in ‘‘favourable conservation status’’. Consequently, in addition to sensitive management of existing sites, it is important to identify sites for habitat recreation. A site-specific investigation of Hook Lake in Hampshire is presented. Previously, on the basis of salinity measurements alone, this site was deemed to have progressed naturally through brackish conditions to a freshwater habitat overgrown by reeds Phragmites sp. A more detailed survey, which considered salinity measurements together with an analysis of substratum heterogeneity and invertebrate fauna diversity, suggests that it is still predominantly a freshwater system with an adjacent brackish/saline ditch. Future management, linked to local biodiversity action plan targets, could proactively support the development of this site as a coastal lagoon in order to secure its integration as part of the international conservation designation. However, this is complicated by the need to then recognise and compensate for loss of freshwater habitat, the need to persuade the local community that any change would not compromise coastal defence integrity and ultimately by medium to long-term coastal defence investment decisions. r 2007 Elsevier Ltd. All rights reserved. Keywords: Habitat re-creation; Biodiversity action planning; EC Habitats Directive; Favourable conservation status; Brackish-water

1. Introduction Coastal or saline lagoons are defined as ‘‘areas of shallow, coastal saline water, wholly or partially separated from the sea by sandbanks, shingle or, less frequently, rocks’’ [1]. The brackish water in coastal lagoons can be the result of ingress of saline water from a minor connecting channel, or from overtopping and/or percolation through the barrier which separates the lagoon from the sea [2]. Salinity varies between lagoons from mesohaline 5–8 g/kg to hyper-saline in the tropics, which can be up to 260 g/kg. Characteristically ‘‘natural’’ coastal lagoons in the UK are restricted to shingle shores [3]. The coastal lagoons of the north–east Atlantic are relatively rare owing to their macrotidal location and their Abbreviations: SAC, Special Area of Conservation; NNR, National Nature Reserve; LNR, Local Nature Reserve; SSSI, Site of Special Scientific Interest; SPA, Special Protection Area; BS, British Standard; CHaMP, Coastal Habitat Management Plan Corresponding author. Tel.: +44 23 8031 9000; fax: +44 23 8031 9739. E-mail address: [email protected] (D.E. Johnson). 0308-597X/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpol.2007.03.004

ephemeral nature. Lagoons are often short-lived as a result of water supply variations, natural succession and landward progression of shingle barriers resulting in infilling. As a result, this habitat is protected as a ‘‘priority habitat type’’ under Annex 1 of the EC Habitats Directive [4]. Currently nine lagoonal animals and two lagoonal plants of the 40 known lagoonal species are protected under Schedules 5 and 8 of the Wildlife and Countryside Act 1981, and comprise some of Britain’s rarest species of plants and animals. One of the highest concentrations of coastal lagoons and saline ponds in the UK is found within the Solent region (Fig. 1). Forty-four lagoonal habitats in total have been identified by Bamber and Barnes [5] between Pagham Harbour and Hengistbury Head, covering approximately 108 ha. Four coastal lagoon complexes—Brading Marshes to St. Helens Ledges, Gilkicker Lagoon; Hurst Castle and Lymington River Estuary, and Langstone Harbour—comprise a SAC. Whilst it has been concluded that the Solent coastal lagoons are relatively stable, north-western European lagoons are generally vulnerable to a number of pressures

ARTICLE IN PRESS 600

D.E. Johnson et al. / Marine Policy 31 (2007) 599–606

Fig. 1. Location of Hook Lake in relation to significant coastal lagoons in the Solent region [6].

[7]. Lagoonal areas normally have insufficient water circulation to buffer changes in water quality and are susceptible to pollution; they are often adversely affected by changes to sea defences, and by demands on freshwater catchments. Management requirements include the need to maintain and monitor stable exchange of waters to and from lagoonal habitats. Water abstractions, for example, known or likely to be affecting lagoonal habitats, may need to be revoked or reduced. In addition, to compensate for historical losses, Pye and French [8] set a UK target for coastal lagoon creation of 120 hectares over 20 years. The Solent region is an area where creation and re-creation are likely to be successful due to the presence of the existing concentration of lagoon habitat, given that many lagoonal species have non-dispersive juvenile stages [9]. One of the ‘potential’ sites, suggested by Bamber et al. [7], for the creation of a new coastal lagoon within the Solent region, is Hook Lake. Hook Lake is part of the Hamble Estuary National Nature Reserve (NNR), the Hook with Warsash Local Nature Reserve (LNR) and the Lee-on-Solent Estuary Site of Special Scientific Interest (SSSI). Furthermore, the LNR is part of a Special Protection Area (SPA) and Ramsar site, designated for wildfowl and wader importance. Historically this was a natural inlet of the sea, used as a harbour in 1600, but then it silted up and was subsequently abandoned. The present lake is the mouth of a small stream dammed at its seaward end by a combination of an accreting shingle bank and sea wall. Within the latter is a pair of sluice gates. Sheader and Sheader [10] classified Hook Lake as lagoonal habitat, based on a salinity recording of 28 g/kg at its seaward end, and the presence of a seepage channel penetrating the shingle embankment. Subsequently, however, Bamber et al. [7] recorded the

salinity in the sluice and throughout the Lake as 0 g/kg, concluding that the site had reverted to a freshwater environment. Between these surveys large flaps were fitted to the seaward side of the sluices as a coastal defence measure and this is likely to have significantly influenced the change. Habitat re-creation has been defined as restoring a site to a condition that once prevailed, or deduced to have prevailed previously, as opposed to habitat creation, which involves the creation of new assemblages of species and habitats for a site [11]. A review of habitat creation and recreation projects in the UK [12] was highly critical and suggested a need for better project planning, monitoring, aftercare and long-term management. Despite these reservations, which centre on a ‘‘lack of scientific certainty’’, there is a growing consensus that habitat conservation must move from being a negative, essentially protectionist activity, to being a positive, creative and managerial one [13]. This paper reviews an investigation into the potential for the re-creation of Hook Lake as a coastal lagoon. 2. Methods A survey of the salinity and substratum heterogeneity of Hook Lake was undertaken using the Venice system of brackish water classification to classify salinities [14] at 16 measuring stations (Fig. 2). This involved plotting mean, maximum and minimum salinity values at each station from two spring tidal cycles and one neap tidal cycle. Salinity was measured using a Grant YSI water quality data logger to an accuracy of 0.1 g/kg. Lagoonal substrate was analysed by measuring particle size distribution. Sediment cores of 83.3 cm3 were taken using a 21.5 cm by 10.3 cm corer at six of the 16 stations. Sub-samples of the

ARTICLE IN PRESS D.E. Johnson et al. / Marine Policy 31 (2007) 599–606

601

Fig. 2. Sampling stations for Hook Lake Survey.

Table 1 Showing combined fauna stations and their respective substratum sample station Substratum sample Combined fauna samples

1 1, 2, 3 and 4

5 5, 6 and 7

cores of approximately 100 g were taken and particle size distribution determined using the wet sieving method set out in BS 1377. Mean grain size, heterogeneity or sorting, skewness in the grain size distribution and kurtosis were calculated using standard methodologies [15]. Lagoonal invertebrate fauna were surveyed during the same time period. Meiofauna and macrofauna of the site’s sediment were sampled by taking sediment cores of 83.3 cm3 using a 21.5 cm by 10.3 cm corer at each survey station. Benthic macrofauna were kick sampled using a 1 mm mesh size net. All samples were kept on ice until arrival at the laboratory. Sediment samples were sieved to 250 mm. All fauna were fixed in 5% formalin and stained with rose bengal. Organisms were identified to species level where possible, and the number of individuals counted. Diversity of samples was calculated using the Shannon– Weinner diversity index. This index is not significantly affected by sample size but is affected by species distribution if a sample contains more than 10 species [16]. Species numbers in each sample from this survey never exceeded 10. Relationships between the diversity values of the two sets of fauna samples and salinity were established using

8 8, 9 and 10

13 12 and 13

15 15

16 16

Pearsons’s product moment correlation coefficient. Combined fauna stations and their respective substratum sample station are shown in Table 1. 3. Results Over the tidal cycles (Fig. 3), mean salinity in the drainage ditch ranged from mixo-oligohaline (stations 5–7) to mixo-mesohaline (stations 1–4). However, salinities as high as 30 g/kg were recorded in the drainage ditch. The seaward end of the lake (stations 9–13) was mixo-oligohaline, with mixo-mesohaline salinities at the sluice gate (station 8) and the relic sluice (station 15). The freshwater inflow station (16) and station 14 were the only limnetic stations with mean salinities of 0.2 g/kg. Both sluice stations maintained mean salinities of 45 g/kg. In terms of particle size distribution (Table 2) the ditch station 1 and freshwater inflow station (16) had poorly sorted, negatively skewed (excessive coarser grains) and leptokurtic sediments with mean grain size of very fine sand. The majority of the lake stations (stations 5, 8 and 15) had more even grain distributions (less negatively skewed and platykurtic) with mean grain sizes in the fine

ARTICLE IN PRESS D.E. Johnson et al. / Marine Policy 31 (2007) 599–606

602

Fig. 3. Mean salinity and salinity range at each station over the tidal cycles.

Table 2 Particle size distribution results Station

Mean grain size (j)

Sorting

Skewness

Kurtosis

1 5 8 13 15 16

3.37 2.97 1.08 2.38 1.94 3.48

1.09 1.41 2.97 3.48 2.76 1.07

1.42 1.13 0.36 1.03 1.06 1.92

3.45 3.44 1.44 2.29 2.61 5.41

sand (station 5), medium sand (station 15) and coarse sand (station 8) fractions. Adjacent to the shingle spit (station 13), however, the distribution was positively skewed and platykurtic, with a mean grain size within the pebble fraction. The distributions of invertebrate species in the sediment cores and kick samples are shown in Tables 3 and 4, respectively. Within both sample types Tubificidae (class: Oligochaeta) and Chironomidae were present in large numbers. The Polychaetes, Nereis diversicolor and Pygospio elegans, were present in the lake but the brackish water beetles, Hydrobius fuscipes and Haliplus confinis, were only present in the drainage ditch. The sipunculan—Nephasoma minuta was only present at station 12. Gammarus salinus was abundant at station 8 and was also present in smaller numbers at stations 10 and 11, whereas Gammarus zaddachi was greatest in numbers at station 8, but lower than that of G. salinus at stations 10 and 11. G. zaddachi had a wider distribution than G. salinus. The freshwater species, Asellus aquaticus (with the exception of one individual), Polycelis nigra, Erpobdella testacea and Sialis lutaria, were only found at the freshwater inflow (station 16). The lagoonal specialist, Lekanosphaera hookeri, was found in the kick samples. Diversity of invertebrate fauna in the samples is shown in Fig. 4. Within the sediment cores diversity was highest at station 9, zero diversity was observed at stations 4 and 15. Fluctuation of diversity indices between stations for the kick samples was slightly less erratic than that of the sediment cores. Overall a decrease in salinity occurred between stations 1 and 16 although two peaks occurred at stations 8 and 16.

No significant correlation (Po0.05) between salinity and diversity was observed for the sediment cores. However, there was a significant negative correlation (Po0.05) between salinity and invertebrate diversity for the kick samples. 4. Discussion Salinity measurements taken as part of this assessment suggest that limnetic conditions recorded by Bamber et al. [7] are now only present at the freshwater inflow and upper part of the lake (stations 14 and 16). All other sampling points, except stations 9–13, were at least mixo-oligohaline and exhibited a wide range of salinity. However, the high percentage of coarse sediment (pebbles) found at the seaward end of the lake adjacent to the shingle spit (station 13) suggests that overtopping of the shingle spit is occurring at this point, possibly causing a fluctuating salinity regime at stations 9–13. Sheader and Sheader [10] noted a breach in this area and local residents have observed that breaching of Hook Spit occurs frequently in winter. The flaps on the main sluices allow minimal ingress of seawater, but the sources of saline water to the lake have been shown to be more diffuse. Temporal and spatial variation of salinity was evident, which is common in the coastal lagoons of Northwest Europe [17]. Swanpool in Falmouth, for example, was classified by Dorey et al. [18] as mixo-oligohaline, in which substantial variations in salinity occur. Generally salinities in coastal lagoons are lowest in winter and highest in summer [19]. On this basis, given that the current survey took place in February, the seaward end of Hook Lake can be classified as coastal lagoon habitat. Biotic survey results further suggest lagoon conditions at Hook Lake. The large tidal flux of water and tidal range at Swanpool [20] encourages the presence of marine species in the pool, which Bamber et al. [21] suggest will lead to marine/estuarine species out-competing lagoonal specialists, the latter dominate tideless lagoons which experience greater environmental variability. Many of the marine/ estuarine species recorded as present by Sheader and Sheader [10], which can out-compete lagoonal specialists, were not recorded during this survey. The invertebrate fauna in Hook Lake is now more akin to the coastal lagoon

ARTICLE IN PRESS D.E. Johnson et al. / Marine Policy 31 (2007) 599–606

603

Table 3 The diversity, species and their numbers found at each station for the sediment cores Taxon

Station 1

2

3

4

5

6

7

8

9

10

Cnidaria Cordylophora caspia Annelida Nereis diversicolor Pygospio elegans Tubificidae Enchytraeidae

12

13

14

15

16

1 1

1

1

10

Nematoda Crustacea Asellus aquaticus Lekanosphaera hookeri Gammarus zaddachi Gammarus duebeni Insecta Chironomidae Simuliidae P individuals P species Diversity (H0 )

11

1 1 32

64

1 2

5

3 17

72 75

6

60

10

2 64

10

21

59

3

1

44 5 2

1

1 1 1

2

4

3 2 0.64

6 3 0.87

1

7

31

11 2 0.3

7 1 0

96 3 0.68

2

3

35 3 0.35

5

8 2 0.66

4 3 1.03

1

32 5 1.27

1

150 5 0.77

70 2 0.41

31 2 0.63

125 3 0.76

12

13

1 1

4 2 0.56

1 2 0

54 6 0.73

Table 4 The diversity, species and their numbers found at each station for the kick samples Taxon

Station 1

Cnidaria Cordylophora caspia

2

3

4

5

6

7

1

8

9

1

10

11

14

15

1

Platyhelminthes Polycelis nigra Annelida Manayunika aestuarina Nereis diversicolor Pygospio elegans Tubificidae Enchytraeidae Erpobdella testacea Nephasoma minuta Nematoda Crustacea Gammarus salinus Gammarus pulex Gammarus sp. Gammarus zaddachi Lekanosphaera hookeri Asellus aquaticus Neomysis integer Palaemonetes varians Insecta Odonata Coenagrion puella Corixidae Sialis lutaria Trichoptera

16

1

3 41

15

108

78

30

38

66

1 4 6 117

11 26 241

2 1

52 116

25 52

34

7

48 1

12 1 80

3

1 9

2 1 1

4 1

2 4

2

1

2

27

20 1

26

2

3 2

4 1

10

1

1

12 14 1

1

7 4

1 1

1

5

3 2

1

1

1

1 10

ARTICLE IN PRESS D.E. Johnson et al. / Marine Policy 31 (2007) 599–606

604 Table 4 (continued ) Taxon

Station 1

Chironomidae Simuliidae Hydrobius fuscipes Haliplus confinis

2 3

3 31

4

5

56

8

6 1

1 1

7 1

8

9 7

10 1

8

11 14

12

13

11

14

15

6

12

16 9 2

1

Mollusca Potamopyrgus antipodarum 1 1 1 1 Opistobranchia 3 4 P 56 16 52 175 90 33 43 192 151 295 21 222 88 47 24 110 P individuals species 6 5 5 9 5 4 5 9 8 8 6 9 4 6 4 9 0.93 1.13 1.02 0.95 0.52 0.4 0.51 1.34 0.82 0.75 1.15 1.44 1.44 0.97 1.14 1.77 Diversity (H0 )

Fig. 4. Mean salinity and diversity (H0 ) of invertebrate fauna within the sediment cores and kick samples.

species composition listed by Bamber et al. [21]. These authors divided characteristic lagoonal species into six suites, species present in the latest survey are listed against Bamber et al. [21] suites below: Suite I.

Suite II. Suite III. Suite IV. Suite V. Suite VI.

Freshwater species—Potamopyrgus antipodarum, Gammarus zaddachi, Gammarus duebeni, Chironomid spp., Unrecorded lagoon species, Euryhaline lagoonal specialists—Lekansphera hookeri, Palaemonetes varians, Stenohaline lagoonal specialists—Pygospio elegans, Estuarine species preadapted to lagoons— Nereis diversiscolor, Estuarine species incidental in lagoons— Neomysis integer, Oligochaeta spp.

The four closely related species of Gammarid—G. duebeni, G. zaddachi, G. salinus and G. locusta—replace each other, in the order listed above, along a salinity gradient from

freshwater to near marine salinity [22]. This relationship was observed in Hook Lake with G. zaddachi and G. salinus. Interestingly P. elegans per se, although classified as a stenohaline lagoonal specialist by Bamber [21], is not a lagoonal specialist and is most abundant on littoral muddy sands (Roger Bamber, personal communication). It occurred between stations 9 and 13 where salinity fluctuated the least over the measurements taken. However, as already mentioned these stations may well be subject to fluctuating salinity. P. elegans is not characteristic of salinities below 4 g/kg [17], but surface waters at these stations were between 0.3 and 1 g/kg. It could then be surmised that percolation of seawater might be occurring through the shingle spit. The presence of Nephasoma minuta at stations 12 and 13 (a species common in shingle enclosing lagoons, where percolation occurs through the sea barrier and salinity is above 20 g/kg) suggests that percolation is occurring at or above these stations. The percolation possibly increases the

ARTICLE IN PRESS D.E. Johnson et al. / Marine Policy 31 (2007) 599–606

interstitial salinity of the sediment to a higher level than that of the surface waters, enabling the survival of N. minuta and P. elegans. Both of these species are characteristic of sandier brackish water sediments [17], and their absence in the drainage ditch, where the sediments were sandy (Table 1), suggests that percolation is limited at other stations. Diversity in the kick samples showed a negative correlation with salinity, which would suggest a predominantly freshwater faunal presence in the lake. The low diversity indices also reflect the hostility of brackish water environments to which many marine and freshwater species are intolerant [3,21]. 5. Future management of hook lake The purpose of the EC Habitats Directive is to maintain or restore at ‘‘favourable conservation status’’, a representative network of natural habitats and species of wild fauna and flora of Community interest. In this respect ‘‘favourable conservation status’’ is defined as a situation where

   

The range and area of habitats are stable or increasing; Population dynamics of species are self-maintaining and viable long-term; The natural range of species is likely to be enhanced and Sufficient areas of habitats exist to maintain species long-term.

The ‘‘Conservation (Natural Habitats & c.) Regulations 1994’’ (Habitats Regulations) translate the EC Habitats Directive into UK legislation. The Habitats Regulations make provision for a management scheme to be developed for each European Marine Site and, for English sites, Natural England has a statutory responsibility for developing conservation objectives and both compliance and condition monitoring [23]. For coastal lagoons this is likely to require: continued notification and designation of all lagoon sites within a cSAC area; assessment of opportunities for habitat improvement and/or creation; identification of water abstractions known or likely to be affecting lagoonal habitats; monitoring and maintenance of stable exchange of waters to and from lagoonal habitats; and the production of individual lagoonal action plans, including objectives for all red data book species. The agenda for coastal lagoon re-creation in Hampshire will be set by the county’s Local Biodiversity Action Plan [24] and by the Solent Coastal Habitat Management Plan [25]. However, forward planning is important. Provisional targets of four to five (2.3 ha) new lagoons are proposed for each of the western and eastern sections of the Hampshire coast. In the short-term at least, coastal habitat re-creation is likely to be opportunistic. Sites, where habitat re-creation is judged to have a high potential for success scientifically, need to be identified and a range of socio-economic issues such as land ownership, stakeholder consensus and public awareness must also be considered [26]. Furthermore,

605

coastal habitat re-creation or realignment options must also plan to replace any associated nature conservation value [27]. In the case of Hook Lake, for example, the reedbed and wet grassland mosaic that currently exists is itself ecologically important. In many cases this process is exacerbated by the development over long time periods of ecological niches that themselves can be difficult or impossible to re-create. Consideration of habitat re-creation opportunities at Hook Lake has been undertaken previously, over the larger 73 ha area of the whole nature reserve [28]. At the time Hampshire County Council recognised potential for a system of lagoons ranging from saline, through brackish to freshwater. However, there were also reservations about modifying features for which the reserve had been declared originally and the SSSI notified. This was compounded by uncertainty about the reaction of locals and elected members’ of the County and District Councils, together with an estimated associated diminution of open market land value of approximately 50%. Over a decade later, prompted amongst other factors by publication of the Environment Agency’s flood map [29], the site is now included within those publically owned and managed coastal land holdings for which the effects of climate change are being considered in detail [30]. The latest survey work has re-confirmed Hook Lake as a predominantly freshwater system with the potential of supporting a brackish water invertebrate fauna. In common with many south coast lagoons the site is fringed with Phragmites sp. and beside the main sluice gates, there are patches of sea club-rush (Scirpus maritimus). Additionally, Hook Lake is not untypical of many sites in the south of England where coastal defences are vulnerable to relative sea-level rise and more brackish conditions are developing behind the sea wall. This site is particularly suitable for re-creation to high quality lagoonal habitat given its position in relation to the tide height of Southampton Water; its location within the cSAC region; and its proximity to the nearest coastal lagoon of regional/ national significance at Ashlett Pond, Fawley. Furthermore—with reference to Bratton [31]—no protected species, freshwater or otherwise were recorded in the lake during this survey and thus re-creation has the potential to achieve biodiversity gains, although it should be noted that large parts of the lake have never been sampled and remain unsampled. The ideal range of salinity for a coastal lagoon is between 15–20 and 40 g/kg, and that is the target at which re-creation of such a habitat should be aimed. Successful conversion of Hook Lake to a coastal lagoon would require reducing the dominance of the freshwater supply from the stream. This is possible with some substantial engineering, which is likely to be prohibitively expensive, or by a management policy of opening the sluice, while still retaining a restricted body of water as a lagoon. To secure biodiversity gains the following management priorities have therefore been identified:

ARTICLE IN PRESS D.E. Johnson et al. / Marine Policy 31 (2007) 599–606

606

   

positive measures to create a more saline water regime by manipulating the sluice gates within the sea wall should be taken; the programme of monitoring and cutting back the Phragmites sp. encroaching the lake should be maintained; shingle movement on Hook Spit should be monitored and, if necessary, measures should be taken to prevent infilling of the open water of Hook Lake; and the water in Hook Lake is flushed once a year to prevent silting. This practice is not favourable to lagoon communities and should stop.

Ultimately, in the medium to long-term, the ecological status of the site will depend on the condition of the sea wall, owned by the Environment Agency. To this end overtopping and underscouring may cause eventual collapse, and the availability of Defra funding for renewal and repair is uncertain. Acknowledgements This work was carried out with support from English Nature. The authors would also like to thank Dr. Roger Bamber for commenting on an earlier version of this paper and Alan Inder for his insight into the management priorities for Hampshire County Council’s coastal estate. References [1] Brown AE, Burn AJ, Hopkins JJ, Way SF. The habitats directive: selection of special areas of conservation in the UK. Joint Nature Conservation Committee Report No. 270. Peterborough: Joint Nature Conservation Committee; 1997. [2] Smith BP, Laffoley D. A directory of saline lagoons and lagoon-like habitats in England. In: English nature science series, vol. 6. Peterborough: English Nature; 1992. [3] Barnes RSK. The coastal lagoons of Britain: an overview and conservation appraisal. Biological Conservation 1989;49:295–313. [4] Council of the European Communities. Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and wild fauna and flora. Official Journal of the European Communities Series L 1992;206:7–50. [5] Bamber RN, Barnes RSK. Coastal lagoons. In: Barne JH, Robson CF, Kaznowska SS, Doody JP, Davidson NC, editors. Coasts and seas of the United Kingdom, Region 9, Southern England: Hayling Island to Lyme Regis. Peterborough: Joint Nature Conservation Committee; 1996. [6] Fowler SC. Review of nature conservation features and information within the Solent and Isle of wight sensitive marine area on behalf of the Solent forum nature conservation topic group. Newbury: Nature Conservation Bureau Ltd.; 1995. [7] Bamber RN, Sheader M, Sheader A, Somes R. Assessment of the Solent saline lagoon resource. Fawley: Fawley Aquatic Research Laboratories Ltd.; 1997. [8] Pye K, French PW. Targets for coastal habitat re-creation. In: English nature science series, vol. 13. Peterborough: English Nature; 1993.

[9] Barnes RSK. The faunas of land-locked lagoons: chance differences and the problems of dispersal. Estuarine, Coastal and Shelf Science 1988;26:309–18. [10] Sheader M. Sheader A. Survey of brackish coastal lagoons: Sussex to Dorset field report. A report for the Nature Conservancy Council. Southampton: University of Southampton; 1984. [11] Jarman R. Habitat Restoration—recanting the status quo. ECOS 1995;16(2):29–38. [12] Parker DM. Habitat creation—a critical review. In: English nature science, vol. 21. Peterborough: English Nature; 1995. [13] Johnson DE. Conserving intertidal wetlands: a regional ecosystembased approach to rehabilitation and re-creation. PhD thesis, Nottingham Trent University; 1998, unpublished. [14] SCCBW Symposium on the classification on the classification of brackish waters. The Venice system for the classification of marine waters according to salinity. Okinos 1958;9(11):310–1. [15] Dyer KR. Coastal and estuarine sediment dynamics. Chichester: Wiley; 1990. [16] Spellerberg IF. Monitoring ecological change. Cambridge: Cambridge University Press; 1994. [17] Barnes RSK. The brackish-water fauna of North-western Europe. Cambridge: Cambridge University Press; 1994. [18] Dorey AE, Colin L, Barnes RSK. An ecological study of the Swanpool, Falmouth: hydrography and its relation to animal distribution. Estuarine and Coastal Marine Science 1973;1:153–76. [19] Barnes RSK. Coastal lagoons: the natural history of a neglected habitat. Cambridge: Cambridge University Press; 1980. [20] Barnes RSK, Dorey AE, Little C. An ecological study of a pool subject to varying salinity (Swanpool, Falmouth). An introductory account of the topography, fauna and flora. Journal of Animal Ecology 1971;40:709–34. [21] Bamber RN, Batten SD, Sheader M, Bridgewater ND. On the ecology of brackish water lagoons in Great Britain. Aquatic Conservation: Marine and Freshwater Ecosystems 1992;2:65–94. [22] Kolding S. Interspecific competition for mates and habitat selection in five species of Gammarus (Amphipoda: Crustacae). Marine Biology 1985;91:491–5. [23] Baxter J. Scientific issues relating to the establishment of conservation objectives and monitoring sites. In: Implementing the EC habitats directive in marine and coastal areas. Luxembourg: European Commission; 1998. p. 23–5. [24] Johnson DE. Coastal biodiversity action planning: a review of progress in Hampshire, England. Periodicum Biologorum 2000; 102(1):7–11. [25] Bray M, Cottle R. Solent coastal habitat management plan: final report. Peterborough: Posford Haskoning; 2003. [26] Hodge M, Johnson DE. Constraint mapping as a means of further refining saltmarsh re-creation opportunities for the Solent region, UK. Coastal Management, in press. [27] McGlashan DJ. Managed relocation: an assessment of its feasibility as a coastal management option. The Geographical Journal 2002; 169(1):6–20. [28] Brooke J. Lagoon creation in southern England. In: Submission for funding under the ACNAT council regulation; 1992, unpublished. [29] Environment Agency Flood Risk Map 2004. Available from: hhttp:// www.environment-agency.gov.uk/subjects/flood/i [accessed 21 July 2006]. [30] Bayliss R. Review of the effects of climate change on Hampshire County Council’s coastal landholdings: Bunny Meadows and Hook with Warsash Key Area Working Group—draft issues and options report; 2005, unpublished. [31] Bratton JH, editor. British red data books 3. In: Invertebrates and other insects. Peterborough: Joint Nature Conservation Committee; 1991.