sussex wetland conference: chris joyce
DESCRIPTION
Saline LagoonsTRANSCRIPT
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Sussex saline lagoonsStatus, changes and challenges
Dr Chris Joyce, School of Environment and Technology
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Key features of saline lagoons
Partial barrier: micro-tidal
Shallow: <1m deep
Saline: 15-40ppt?
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Lagoon ecology
• Ecosystem services, e.g. buffers, productive, recreation
• Rare: 5% of European coasts - priority for EU Habitats Directive
• Specialist lagoonal species, e.g. invertebrates, many legally protected
• Variable resource with diverse origins
• ‘Natural’ lagoons are very rare and may be short-lived
• Artificial lagoons include mill ponds, marinas, and gravel pits
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Status survey of Sussex lagoons
• Estimated resource of 35 lagoons comprising 184ha
• 28 surveyed in summer 2001• Flora (n=10 per site)• Fauna (invertebrates, n=15 per site)• Environmental variables: 13 hydrological
and biogeographical characteristics
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Survey results: invertebrate fauna
• A• P
ett
3• P
ett
4• C
am1
• B• P
ett
1• P
ett
2
• C• Ca
mber 2
• Hooe
• Long
Pool
• Sidlesham
• D• Rye Hbr• N’pt Pit
• N’pt Small• Camber 3
• E• Ch. Norton• Birdham• Slipper• Peter
• F• Quarry, Rye• Wader, Rye• Newhaven• Oxbow, Cu• Tidal, Cu
• Scrape, Cu• Pagham• Thorney
• G• Widewater
• I• Little Spit
• H• Bton Mar
• marine
• Lymnaea peregra• Cerastoderma glaucum• Hydrobia ulvae
Source: after Joyce et al. (2005)
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Survey results: invertebrate fauna
EA
C
FB
D
HG
Axis 1 (SD)
Axis
2 ( S
D)
2 4
2 I
Salinity, shape, isolation, substrate, bank slope,connection to sea
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Survey conclusions
• 13 of 28 sites supported a lagoonal community, comprising 64ha • saline (usually >28ppt)• ‘reliable’ connection to sea, e.g. sluice• partial tidal exchange
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Changes at Widewater lagoon, Lancing
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22 Jun 01
7 Jul 01
20 Aug 01
21 Aug 02 22 Jul 03
31 Aug 04
24 Aug 05
SALINITY (ppt)
33 26 28 26 33 40 37
FLORA (%)
Ruppia maritima
31 31 36 29 24 33 30
FAUNA (no.)
Hediste diversicolor
14 4 49 55 16
Perinereis cultrifera
1 2 20
Hydrobia ventrosa
2081 1416 552 342 671 110 298
Cerastoderma glaucum
247 84 194 23 216 115 60
Palaemonetes varians
3 12 20 81 48 9
Microdeutopus gryllotalpa
308
Widewater changes
Source: after Joyce (2006)
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Changes at Pagham lagoon
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Pagham lagoon changes
19 Jun 01 23 Aug 05 29 Aug 07
20 Sep 11
SALINITY (ppt) 2.5 12 13 10.5
FLORA (%)
Ruppia maritima 10.5 22
FAUNA (no.)
Nematoda 91
Capitella capitata 37
Tubificoides sp. 355 1
Hydrobia ventrosa
1 1 10
Cerastoderma glaucum
17 21 14
Lekanosphaera hookeri
273 28 121 106
Source: after Joyce (2011)
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Conservation challenges
• Climate change, e.g. storms, sea level rise
• Invasion ‘hot spots’?• ‘Poor relation’ to freshwater and marine
systems• Classifying and quantifying the lagoonal
resource base• Managing lagoons specifically but within
the coastal ecocomplex• Lack of scientific understanding
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Research challenges
• Co-ordinated research and monitoring to establish the lagoon resource and baseline ecology
• Longer-term, specialised methods that assimilate lagoon dynamics
• Developing biological indicators, e.g. fish, invertebrates
• An ecocomplex approach that acknowledges the transitional and networked nature of lagoonal patches within the coastal landscape
Source: Beer and Joyce (in review)
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Acknowledgements
Natural England
West Sussex County Council
Earthwatch Institute
Dr Cristina Vina-Herbon, JNCC
Dr Cath Waller, Hull University
Dr Nicola Beer
All the field and lab teams