Intertidal survey of Morecambe Bay and the
Duddon Estuary
English Nature
February 2006
Final Report
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Document title
Status
Intertidal survey of Morecambe Bay and the
Duddon Estuary
Final Report
Date
February 2006
Client
English Nature
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CONTENTS
Page
1
INTRODUCTION
1.1
Background
1.2
Aims and objectives
1
1
1
2
METHODOLOGY FOR THE STUDY
2.1
Introduction
2.2
Survey coverage and scope
2.3
Overview of sampling technique
2.4
Reporting and GIS
2.5
Health and safety
2
2
2
2
4
4
3
RESULTS OF BIOLOGICAL SURVEY
3.1
Introduction
3.2
Duddon Estuary
3.2.1
Transect A: Haverigg Point
3.2.2
Transect B: Angerton Marsh, upper Duddon estuary
3.2.3
Transect C: Millom Marsh to Kirkby in Furness
3.2.4
Transect D: Duddon Sands
3.2.5
Transect F: North End Marsh, Walney Channel
3.2.6
Transect G: Walney Channel
3.3
Morecambe Bay
3.3.1
Transect H: Westfield Point to Snab Sands
3.3.2
Transect I: Haws Bed
3.3.3
Transect J: South End Haws
3.3.4
Transect K: Rampside
3.3.5
Transect L: Roosebeck Sands
3.3.6
Transect N: Mortbank
3.3.7
Transect O: Baycliff to Ulverston Channel
3.3.8
Transect P: Hammerside Point
3.3.9
Transect R: Cartmel Sands
3.3.10
Transect S: Cartmel Wharf
3.3.11
Transect T: Grange over Sands
3.3.12
Transect U: Milnthorpe Sands / Kent Channel
3.3.13
Transect V: Warton Sands
3.3.14
Transect W: Morecambe (North)
3.3.15
Transect X: Morecambe
3.3.16
Transect Y: Aldrens Hedge Baulks
3.3.17
Transect Z: Mussel Knott End Skear to Sandylands
3.3.18
Transect AA: Knott End to Heysham
3.3.19
Transect BB: River Lune
3.3.20
Transect CC: Cockerham Sands
3.3.21
Transect DD: River Wyre
3.3.22
Transect EE: North Wharf, Fleetwood
3.3.23
Transect FF: Sandylands (2)
5
5
9
9
10
10
11
11
12
13
13
13
14
15
15
16
16
17
17
18
19
19
20
21
21
22
23
24
24
25
26
26
27
4
DISCUSSION
28
Intertidal survey of Morecambe Bay
and the Duddon Estuary
-i-
English Nature
February 2006
1
INTRODUCTION
1.1
Background
As the statutory nature conservation agency for England, English Nature has the
responsibility for the identification and protection of sites intended to conserve important
wildlife and Earth science features. Such sites may be designated as Sites of Special
Scientific Interest (SSSI) under national legislation or Special Areas of Conservation
(SAC) and Special Protection Areas (SPA) under European legislation. In order to
assess the effectiveness of legislative and policy measures in contributing to biodiversity
conservation, regular monitoring of sites is undertaken.
The intertidal habitats of Morecambe Bay and the Duddon Estuary are an important
interest feature in the designations of these areas. A broad objective of the current
study, therefore, is to provide data on the status of the intertidal habitats of these areas
to support the overall monitoring programme of the sites. The ultimate aim is that the
data will form part of the condition assessment for these sites.
Morecambe Bay and Duddon Estuary are designated as a single SAC; the Morecambe
Bay SAC. Both Morecambe Bay and the Duddon Estuary are also designated as SSSI,
SPA and Ramsar sites.
This report describes the aims and objectives of the study, the methodology employed in
the survey work and analysis if data, presents the results of the surveys and concludes
by describing the findings of the study and making recommendations.
1.2
Aims and objectives
As noted in Section 1.1, a broad objective of the study is to provide data on the status of
the intertidal habitats of Morecambe Bay and the Duddon Estuary in order to support the
overall monitoring programme of the designated sites. The specific objectives of the
study were discussed in detail at a project start-up meeting held between English Nature
and Royal Haskoning on 19 August 2004 and can be summarised as follows:




Definition of the extent of intertidal sediment and the interface with saltmarsh;
The composition of intertidal soft sediment biotopes;
Sediment character (based on quantitative and qualitative sampling); and,
Biotope distribution.
The methodology for the survey work is described in Section 2 and is designed to fulfil
the above objectives of the study and to reflect the discussions held at the start-up
meeting.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
-1-
English Nature
February 2006
2
METHODOLOGY FOR THE STUDY
2.1
Introduction
The survey work was undertaken over three separate periods. This was necessary
given that the timing of the award of contract coincided with the autumn/winter period
which meant that the survey work had to be coordinated with both spring tide conditions
and periods of good weather. The extended overall survey period is largely a
consequence of short day length which restricts working time combined with the large
study area. The survey periods are as follows:



2.2
29th August 2004 to 1st September 2004;
27th September 2004 to 1st October 2004;
8th March 2005 to 10th March 2005.
Survey coverage and scope
Prior to commencing the survey, a plan for the work was agreed with English Nature. A
series of pre-determined transects were established and these transects were
specifically selected to provide the appropriate spatial coverage to meet the objectives
for the survey as set out in Section 1. Specifically, transects were established and
aligned so as to maximise data collection at locations characterised by biotopes of high
conservation value or biotopes subject to change due to anthropogenic or natural
processes. In total, 29 transects were established, the locations of which are presented
in Figure 2.1 which resulted in a total surveyed transect length of almost 99km.
As a consequence of the transect-based approach to the survey work it was agreed that
the mapping of biotope boundaries was not an appropriate output of the study and that
the study would provide an assessment of biotope diversity and composition. It was
further agreed that the survey work would not comprise quantitative sampling for
infaunal species and that it would be preferable to obtain more quantitative detail on
sediment characteristics throughout the survey area.
2.3
Overview of sampling technique
Given the large scale of the survey area and the very dangerous conditions that
characterise the site, an Osprey 5 hovercraft was used to transport surveyors and
equipment between sampling stations. Sampling was undertaken at a number of
sampling stations along each of the 29 pre-defined transects. Individual sampling
stations were not pre-defined and were chosen where there was a noticeable visual
change in sedimentary conditions or species along the transect, or, in instances where
the sediment appeared uniform, sampling was undertaken at regular intervals that were
appropriate for the length of the transect.
At each sampling station, the following records were taken:





Location (as a 10 figure British National Grid reference (WGS 84) using GPS);
Noticeable species present and notes on abundance;
Sediment characteristics (e.g. sediment type, presence of anoxic layer, etc)
Photographs;
Supplementary target notes of any other features of interest.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
-2-
English Nature
February 2006
Fig 2.1
Intertidal survey of Morecambe Bay
and the Duddon Estuary
-3-
English Nature
February 2006
A number of samples were taken for subsequent analysis of particle size distribution
from each transect. The rationale for taking these samples was to aim to achieve as
complete a spatial coverage of the survey as possible. The analysis of sediment
samples for particle size distribution was carried out by the Institute of Estuarine and
Coastal Studies (IECS) at the University of Hull on behalf of Royal Haskoning.
At the end of each survey data, all of the field records were input to master spreadsheet
of data for subsequent incorporation into the GIS.
2.4
Reporting and GIS
The main output of the study is a GIS which contains all of the findings of the survey
work, including all of the photographs, and the quantitative results of the sediment
quality analysis. This report is intended to complement the GIS in that it gives an
overview of the biotopes encountered on each transect and discusses in further detail
the findings of the survey. The report also contains hard copies of some of the maps
presented within the GIS showing, for examples, sample locations.
In accordance with English Nature’s project specification, biotopes have been assigned
according to the 1997 Marine Nature Conservation Review (MNCR) marine biotope
classification system. Where an assemblage of species did not match MNCR
descriptions exactly, a ‘best-fit’ biotope was assigned which most closely matched the
biotope description. Where it was judged that there was a high level of uncertainty in
the biotope classification, a higher level biotope code was assigned.
2.5
Health and safety
The large intertidal area within the study area presented a variety of important health
and safety considerations, and there are inherent severe risks associated with working
in this area. Given this, the survey team were accompanied by a member of the local
RNLI crew with an intimate knowledge of the area and who was able to indicate where it
was safe to survey and provide advice on the location of launch sites and impassable
channels. This proved invaluable to the survey and is considered to be a crucial
consideration for any future survey work that may be undertaken.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
-4-
English Nature
February 2006
3
RESULTS OF BIOLOGICAL SURVEY
3.1
Introduction
This section summarises the characteristics of each of the transects that were surveyed,
including the location and orientation of the transect and a general description of the
biotopes encountered with reference to the substrata and communities present.
Transect reference codes are as presented in the accompanying GIS and names have
been assigned to each transect to identify approximate location. Figure 2.1 shows the
location of each transect. Table 3.1 below provides a summary of length of each
transect and the sampling that was undertaken on each transect.
Table 3.1
Summary of each surveyed transect with details of sampling that
was undertaken
Transect
Approximate transect location
Transect
length
(km)
Number of
sample
stations
A
B
Haverigg Point
Hodbarrow-Point – Askam in
Furness
Millom Marsh
Askam
Walney Island (North)
Walney Meetings
Westfield Point/Gas terminal
Haws Bed
South End Haws Seaward
Rampside
Roosebeck Sands
Mortbank
Baycliff to Ulverston Channel
Hammerside Point
Cartmel Sands
Cartmel Wharf
Grange Over Sands
Milnthorpe Sands / Kent Channel
Warton Sands
Morecambe (North)
Morecambe
Aldrens Hedge Baulks
Knott End Skear to Sandylands
Knott End to Heysham
River Lune
Cockerham Sands
River Wyre
North Wharf, Fleetwood
Sandylands (2)
2
1.5
6
6
3.8
3.2
1.3
0.3
3.3
3.1
0.3
2.4
3.8
3.6
1.4
2.7
12.3
10
3.5
1.8
5.5
3.6
1.3
1.2
1.5
12.5
4.3
1.5
2.0
3.3
1.7
7
5
8
5
11
9
5
10
3
5
8
9
3
9
5
7
9
14
6
7
8
12
12
10
5
9
4
C
D
F
G
H
I
J
K
L
N
O
P
R
S
T
U
V
W
X
Y
Z
AA
BB
CC
DD
EE
FF
Intertidal survey of Morecambe Bay
and the Duddon Estuary
-5-
English Nature
February 2006
A summary of the biotopes encountered along each transect is provided in Table 3.2
below.
Table 3.2
Transect
A
B
Summary of the biotopes encountered on each transect
Biotope
LGS.BarSnd
LMS.MacAre
LMU.Sm
LMS.BatCor
LMU.SMu
C
LMU.HedMac
LMU.Sm
LMS.MacAre
LGs.BarSnd
D
LMS.BatCor
LMU.Sm
LGS.BarSnd
LMS.MacAre
F
G
H
LMS.PCer
LMU.Sm
LGS.BarSnd
LMS.Pcer
LMS
LMX
LMU.Sm
LMU.Mu
SLR.FvesX
SLR.MytX
SLR.FvesX
LMS.Zos
LMU.Sm
LMS.MacAre
LMU.Smu
Intertidal survey of Morecambe Bay
and the Duddon Estuary
Biotope description
Barren course sand shores
Macoma balthica and Arenicola marina in muddy sand
shores
Saltmarsh
Bathyporeia spp. and Corophium spp. in upper shore
slightly muddy fine sands
Sandy mud shores
Hediste diversicolor and Macoma balthica in sandy mud
shores
Saltmarsh
Macoma balthica and Arenicola marina in muddy sand
shores
Barren course sand shores
Bathyporeia spp. and Corophium spp. in upper shore
slightly muddy fine sands
Saltmarsh
Barren course sand shores
Macoma balthica and Arenicola marina in muddy sand
shores
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Saltmarsh
Barren course sandy shores
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Littoral muddy sands
Littoral mixed sediments
Saltmarsh
Soft mud shores
Fucus vesiculosus on mid eulittoral mixed substrata
Mytilus edulis beds on eulittoral mixed substrata
Fucus vesiculosus on mid eulittoral mixed substrata
Littoral Zostera (seagrass) beds
Saltmarsh
Macoma balthica and Arenicola marina in muddy sand
shores
Saltmarsh
-6-
English Nature
February 2006
Table 3.2
I
(continued)
SLR.MytX
LMS.MacAre
LMU.HedMac
LMU.Sm
LGS.BarSh
J
LGS.AP.P
K
MLR.EntPor
LMU
LMX
LGS
LMU.Sm
LMU.Smu
LMU.HedMac
L
LMS.Pcer
SLR.MytX
LGS
LMS.MacAre
LMS.Pcer
N1
SLR.Bllit
LMS
O1
LMS.MacAre
LGS.BarSh
LMS.MacAre
LGS.S
LMS.MS
P
LMU.Sm
LGS.S
LGS.AP.P
LMS.Bat Cor
R
LMS.BatCor
Intertidal survey of Morecambe Bay
and the Duddon Estuary
Mytilus edulis beds on eulittoral mixed substrata
Macoma balthica and Arenicola marina in muddy sand
shores
Hediste diversicolor and Macoma balthica in sandy mud
shores
Saltmarsh
Barren coarse sandy shores
Burrowing amphipods and polychaetes (often with
Arenicola marina) in clean sand shores
Porphyra purpurea or Enteromorpha spp. On sandscoured mid or lower eulittoral rock
Littoral muddy shores
Littoral mixed sediments
Littoral gravels and sands
Saltmarsh
Sandy mud shores
Hediste diversicolor and Macoma balthica in sandy mud
shores
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Mytilus edulis beds on eulittoral mixed substrata
Littoral gravels and sands
Macoma balthica and Arenicola marina in muddy sand
shores
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Barnacles and Littorina littorea on unstable eulittoral
mixed substrata
Littoral muddy sands
Macoma balthica and Arenicola marina in muddy sand
shores
Barren shingle or gravel shores
Macoma balthica and Arenicola marina in muddy sand
shores
Sand shores
Muddy sand shores
Saltmarsh
Sand shores
Burrowing amphipods and polychaetes (often with
Arenicola marina) in clean sand shores
Bathyporeia spp. And Corophium spp. In upper shore
slightly muddy fine sands
Bathyporeia spp. And Corophium spp. In upper shore
slightly muddy fine sands
-7-
English Nature
February 2006
Table 3.2
(continued)
S
LMS.PCer
LMS.MacAre
T
U
V
LMU.HedMac.Are
LMU.Sm
LMU.Sm
LMU.Mu
LMS.MS
LMU.Mu
LMU
LMS
LMU.Sm
LMS
LMS.PCer
LMS.BatCor
LGS
W
LMS.PCer
LMS.BatCor
LMU.HedMac.Are
LMS.PCer
LMU.HedOl
X
SLR.BLlit
LMS
LMS
Y
LMS.PCer
SLR.MytX
SLR.MytX
SLR.BLlit
LGS.AP.P
LGS
LMS
Intertidal survey of Morecambe Bay
and the Duddon Estuary
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Macoma balthica and Arenicola marina in muddy sand
shores
Hediste diversicolor, Macoma balthica and Arenicola
marina in muddy sand or sandy mud shores
Saltmarsh
Saltmarsh
Soft mud shores
Muddy sand shores
Soft mud shores
Littoral muds
Littoral muddy sands
Saltmarsh
Littoral muddy sands
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Bathyporeia spp. and Corophium spp. in upper shore
slightly muddy fine sands
Littoral gravels and sands
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Bathyporeia spp. and Corophium spp. in upper shore
slightly muddy fine sands
Hediste diversicolor, Macoma balthica and Arenicola
marina in muddy sand or sandy mud shores
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Hediste diversicolor and oligochaetes in low salinity
shores
Barnacles and Littorina littorea on unstable eulittoral
mixed substrata
Littoral muddy sands
Littoral muddy sands
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Mytilus edulis beds on eulittoral mixed substrata
Mytilus edulis beds on eulittoral mixed substrata
Barnacles and Littorina littorea on unstable eulittoral
mixed substrata
Burrowing amphipods and polychaetes (often with
Arenicola marina) in clean sand shores
Littoral gravels and sands
Littoral muddy sands
-8-
English Nature
February 2006
Table 3.2
(continued)
Z
LGS.AP
SLR.MytX
AA
BB
CC
SLR.Blit
MLR.Salv
LMS
LMS.PCer
LMS
LMU.Smu
LMS
LMS.MS
LMU.Sm
LMU
LMS
SLR.Fspi
LMU.Sm
LMS
LMS.BatCor
DD
LMS.BatCor
LMU.Mu
LMU.Smu
EE
FF
SLR.BLlit
LGS
LMU
LGS.BarSh
LMS.MacAre
LMS.MS
LMS.MacAre
3.2
Duddon Estuary
3.2.1
Transect A: Haverigg Point
Burrowing amphipods and polychaetes in clean sand
shores
Mytilus edulis beds on eulittoral mixed substrata
Barnacles and Littorina littorea on unstable eulittoral
mixed substrata
Sabellaria alveolata reefs on sand-abraded eulittoral rock
Littoral muddy sands
Polychaetes and Cerastoderma edule in fine sand and
muddy sand shores
Littoral muddy sands
Sandy mud shores
Littoral muddy sands
Muddy sand shores
Saltmarsh
Littoral muds
Littoral muddy sands
Fucus spiralis on moderately exposed to very sheltered
upper eulittoral rock
Saltmarsh
Littoral muddy sands
Bathyporeia spp. and Corophium spp. in upper shore
slightly muddy fine sands
Bathyporeia spp. and Corophium spp. in upper shore
slightly muddy fine sands
Soft mud shores
Sandy mud shores
Barnacles and Littorina littorea on unstable eulittoral
mixed substrata
Littoral gravels and sands
Littoral muds
Barren shingle or gravel shores
Macoma balthica and Arenicola marina in muddy sand
shores
Muddy sand shores
Macoma balthica and Arenicola marina in muddy sand
shores
Extending in a south-west direction from the sand dunes of Haverigg Point, transect A
runs for approximately 2 km across a large expanse of rippled medium to coarse
intertidal sand punctuated by standing pools of water. The six sampling stations along
this transect exhibited a general paucity of infauna which may be expected in coarser
sediments of this nature. The upper foreshore of rounded cobbles and pebbles is
backed by an established sand dune system.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
-9-
English Nature
February 2006
Plate 3.1
3.2.2
View of transect A off Haverigg Point
Transect B: Angerton Marsh, upper Duddon estuary
Located in the upper Duddon Estuary, Transect B runs from the grazed Angerton
saltmarsh south of Foxfield to Millom Marsh on the western shore of the estuary. The
sediment type along the transect is predominantly sandy mud/muddy sand with higher
mud content towards the banks. The sediment at stations at higher level on the shore
closer to the saltmarsh edge is intensively burrowed by the mud shrimp Corophium
volutator. The Baltic tellin Macoma balthica is also present.
Plate 3.2
3.2.3
View of transect B off Angerton Marsh
Transect C: Millom Marsh to Kirkby in Furness
From Kirkby in Furness, transect C crosses the Duddon Sands and the Duddon Channel
to Millom Marsh. Elevated banks are present in the mid-channel while the muddier
Intertidal survey of Morecambe Bay
and the Duddon Estuary
- 10 -
English Nature
February 2006
sediments adjacent to the saltmarsh either side of the channel contain Macoma balthica,
Corophium volutator and the laver spire shell Hydrobia ulvae.
Plate 3.3
3.2.4
View of grazed saltmarsh at Millom Marsh on transect C
Transect D: Duddon Sands
Medium sand dominates the sediment of this transect which runs from just south of
Askam in Furness to the Haverigg Nature Reserve. The western shore adjacent to the
rock revetment of nature reserve is heavily rippled with large standing pools of water.
The mobile and coarse nature of the sediments at this site is likely to be the primary
reason for the lack of conspicuous species present. The mid channel is characterised
by multiple channels with megaripples of medium sand and here infauna is limited to
Arenicola marina which is occasional to abundant. On the eastern shore a muddier
substrate, anoxic at approximately 10cm, supports Cerastoderma edule and Hediste
diversicolor.
3.2.5
Transect F: North End Marsh, Walney Channel
From North End Marsh to north of Sowerby Lodge, Transect F crosses the Scarth
Channel and a 1km stretch of relatively barren medium to fine sand. Isolated muddier
areas support Cerastoderma edule and Hediste diversicolor. The western shore is
backed by saltmarsh, the eastern upper shore comprises mixed sediment matrix over
clay.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
- 11 -
English Nature
February 2006
Plate 3.4
3.2.6
View of transect F looking across the Scarth Channel
Transect G: Walney Channel
The sample stations of this transect predominantly comprise a matrix of coarse sand,
pebbles, boulders with occasional shell fragments interspersed with small standing
pools of water. The brown algae Fucus vesiculosus and Ascophyllum nodosum are
attached to larger rocks and provide habitat for Patella vulgata, Semibalanus
balanoides, Elminius modestus, Carcinus maenas, amphipod spp. and Littorina littorea.
The western shore is backed by a narrow (less than 5m wide) strip of saltmarsh. This
transect also has patchy mussel beds.
Plate 3.5
View of transect G with patchy mussel beds in the background
Intertidal survey of Morecambe Bay
and the Duddon Estuary
- 12 -
English Nature
February 2006
3.3
Morecambe Bay
3.3.1
Transect H: Westfield Point to Snab Sands
On the eastern shore of the Walney Channel adjacent to the Gas Terminal, a rock
revetment backs the mixed sediment of the upper shore. Patches of Fucus vesiculosus
are attached to stones which also support species such as Patella vulgata,
Cerastoderma edule, Hediste diversicolor and Littorina littorea. An area of patchy
saltmarsh is punctuated with shallow channels and Enteromorpha covered mud banks.
Zostera is found in standing pools of water and shallow channels. After approximately
300m from the upper shore the sediment graduates to a muddy sand which is anoxic at
about 5cm; this substratum continues to the opposite side of the channel at Snab
Sands. In the muddy rippled sand of Snab Sands, C. edule and Corophium volutator
are found until, at the saltmarsh boundary, fine mud prevails and high numbers of
Hydrobia ulvae are found on the sediment surface.
Plate 3.6
3.3.2
Zostera beds in the Walney Channel
Transect I: Haws Bed
Transect I extends from the Barrow RNLI lifeboat station westwards across the Piel
Channel and Haws bed at the southern end of Walney Island. Adjacent to the lifeboat
station, Mytilus edulis beds also support Semibalanus. balanoides, Littorina. littorea and
Hediste diversicolor. To the west of the channel the sand is cleaner with Macoma
balthica and Cerastoderma edule present. Towards the saltmarsh of Haws bed,
Corophium volutator, Cerastoderma edule and Hediste diversicolor are found in muddier
sediment. The upper shore consists of well rounded cobbles and pebbles on
sand/gravel matrix.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
Plate 3.7
3.3.3
View of the lifeboat station at Barrow with mussel beds in the
foreground
Transect J: South End Haws
From the southern tip of Walney Island, transect J extend westwards from an upper
shore of predominantly coarse sand and cobbles on mixed sediment matrix. A band of
cobbles and pebbles interspersed with large areas of standing water support Porphyra
purpurea, Enteromorpha sp. and Fucus vesiculosus. Semibalanus balanoides and
Carcinus maenas are found in and around larger boulders. From the mid to lower shore
stable medium coarse sand dominates with the occasional presence of Arenicola
marina.
Plate 3.8
View along transect J with stable cobble skear at South End Haws
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
3.3.4
Transect K: Rampside
From an upper shore of coarse sand with shell fragments adjacent to Rampside,
transect K passes through a fragmented saltmarsh belt of Spartina and Salicornia. The
substratum in this area comprises anoxic sandy mud with Cerastoderma edule and
Hydrobia ulvae. Further seawards, approximately 1km from the shore, fine mud
supports Hediste diversicolor, C. edule, Nephtys and Macoma balthica.
Immediately adjacent to Foulney Island an area of extensive mussel bed on a substrate
of muddy sand is present. The algae Porphyra purpurea, Fucus vesiculosus and
Chondrus crispus are scattered. In addition to the banks of Mytilus edulis other faunal
species include C. edule, H. diversicolor and H. ulvae.
Plate 3.9
3.3.5
View of transect K showing fragmented saltmarsh in the foreground
Transect L: Roosebeck Sands
From an upper shore of clean medium sand with abundant cockle shells, transect L
crosses an area of muddy sand which is anoxic at between 1cm and 5cm depth. The
species assemblage is dominated by Cerastoderma edule and Macoma balthica.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
Plate 3.10
3.3.6
Typical view of the substratum (muddy sand) on transect L
Transect N: Mortbank
The foreshore is largely medium sand with scattered boulders. Associated with these
boulders are Semibalanus balanoides, Littorina littorea, Carcinus maenas and Mytilus
edulis. Extending toward the south-east the remainder of the transect comprises muddy
sand and supports C. edule, Hediste diversicolor and Macoma balthica.
Plate 3.11
3.3.7
View of transect N showing large boulders on medium sand
Transect O: Baycliff to Ulverston Channel
Transect O begins with an upper shore zone of Enteromorpha covered pebbles and
cobbles and covers an expanse of muddy sand for the remainder of its length. The
muddy sands are dominated by Macoma balthica and Arenicola marina.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
Plate 3.12
3.3.8
Typical view of the substratum at transect O
Transect P: Hammerside Point
Transect P runs from Hammerside Point, Ulverston westwards across to Cartmel Sands
across the point where the River Leven meets Morecambe Bay, south of the Leven
viaduct. Sediments are predominantly muddy sand with Hediste diversicolor. The
eastern end of the transect is muddy sand and is interspersed with fragmented
saltmarsh where high numbers of the mud snail Hydrobia ulvae are found. Sediments
become heavily gullied toward the marsh.
3.3.9
Transect R: Cartmel Sands
From the seaward extent of the saltmarsh belt, transect R runs southwards and
comprises rippled muddy sand at all stations sampled and is heavily burrowed by
Corophium volutator with Cerastoderma edule present in low numbers.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
Plate 3.13
3.3.10
Rippled muddy sand at transect R which is heavily burrowed by
Corophium volutator
Transect S: Cartmel Wharf
Transect S is approximately 10 km long and extends over the length of Cartmel Wharf
sandflats to the central area of Morecambe Bay. The transect is predominantly muddy
sand over the entire length. Cerastoderma edule is present at stations on the mid to
lower shore, but at relatively low density.
Plate 3.14
View of transect S (Cartmel Wharf sandflats)
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
3.3.11
Transect T: Grange over Sands
At the point where the River Kent meets Morecambe Point, transect T starts at Holme
Island, Grange over Sands and crosses the Kent channel in a south-east direction
towards Arndale Park. Adjacent to Holme Island, and backed by the railway
embankment, a dense saltmarsh predominantly comprising the cord grass Spartina
anglica is present. The open expanse of muddy sand between Holme Island and
Arndale Park is largely devoid of conspicuous infauna but polychaete casts are present,
albeit in very low numbers.
Plate 3.15
3.3.12
Pioneer saltmarsh (left) and mudflats (right) adjacent to Holme
Island, Grange over Sands
Transect U: Milnthorpe Sands / Kent Channel
Transect U covers an area of sandy mud interspersed with variable narrow channels.
The muddy sand is anoxic at about 0.5cm depth with no conspicuous infauna and a
small amount of organic detritus covers some areas of mudflat.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
Plate 3.16
3.3.13
Muddy sand largely devoid of conspicuous infauna (Milnthorpe
Sands)
Transect V: Warton Sands
The upper shore is predominantly muddy sand which is anoxic at about 15cm with
Macoma balthica, Corophium volutator and occasionally Cerastoderma edule. From the
mid to lower shore the sediment is largely fine sand and Cerastoderma edule is common
to abundant.
Plate 3.17
View of transect V showing commercial cockle (C. edule) harvesting
in the background
Intertidal survey of Morecambe Bay
and the Duddon Estuary
- 20 -
English Nature
February 2006
3.3.14
Transect W: Morecambe (North)
The mid to upper shore comprises mixed sediment to include boulders, cobbles,
pebbles, gravel and coarse sand. Semibalanus balanoides, Littorina littorea and
Littorina saxatilis are present on the larger boulders while Mytilus edulis and Carcinus
maenas are found amongst the finer substrates and standing pools of water. A band of
clayey mud with bivalve shell fragments supports C. edule (abundant), Corophium
volutator, Hydrobia ulvae (abundant), Hediste diversicolor and L. littorea.
On the mid shore there are deep meandering gullies (1m to 1.5m deep) formed in
muddy sand with shell fragments. On the mid to low shore the sediment is
predominantly muddy sand with C. volutator, C. edule and H. diversicolor.
Plate 3.18
3.3.15
Transect W with meandering gullies in muddy sand, North
Morecambe
Transect X: Morecambe
Orientated in a north-westerly direction from Morecambe, Transect X incorporates
biotopes of muddy sand and mussel beds. The sediment is generally anoxic between 2
and 5cm deep. In addition to the abundant Mytilus edulis, the mussel beds also support
Hydrobia ulvae, Carcinus maenas and Littorina littorea. Cerastoderma edule is
occasionally present within mussel beds and stations situated in open muddy areas.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
Plate 3.19
3.3.16
Transect X showing mussel beds off Morecambe
Transect Y: Aldrens Hedge Baulks
Between the seafront and the skear the sediment is muddy sand displaying a general
paucity of conspicuous infauna with the exception of Arenicola marina. Further seaward
the skear by the Aldrens Hedge Baulks provides the substrate for a bed of Mytilus edulis
which is present in superabundant quantities.
Adjacent to the remains of the wooden fishing baulks is a band of cobbles and boulders
on mixed sediment matrix. Enteromorpha sp., the ephemeral green alga, covers
boulders which are also colonised by Porphyra purpurea as well as M. edulis,
Semibalanus balanoides, Littorina littorea, Carcinus maenas and Gammaridae under
boulders.
At the end of the transect by the starboard marker, a superficial layer of muddy fine sand
over a mixed sediment matrix is interspersed with cobbles and fragments of Sabellaria
reef. The area represents a patchy M. edulis bed with Lanice conchilega abundant in
the mud. Rocks are colonised by S. balananoides and an evenly distributed surface
layer of Ulva lactuca.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
Plate 3.20
3.3.17
Mussel beds by Aldrens Hedge Baulks on transect Y
Transect Z: Mussel Knott End Skear to Sandylands
Transect Z has a variety of biotopes along its 1.5km length. Muddy sand with
occasional Arenicola marina casts with small pools of standing water. On reaching the
Heysham Flat the sandy mud gives way to large pools of standing water on a
sand/mud/shell matrix with large scattered boulders colonised by Mytilus edulis and
Semibalanus balanoides. Adjacent to this, extensive mussel beds of M. edulis are
present in which S. balanoides, Littorina littorea are also found. Towards Knott End
Skear large formations of Sabellaria reef sit within patchy mussel bed and interstitial muds
populated by Lanice conchilega.
Plate 3.21
Sabellaria reefs near Mussel Knott End Skear
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
3.3.18
Transect AA: Knott End to Heysham
Transect AA runs for 12.5 km from the slipway at Knott End to the power station at
Heysham. The transect crosses the Lune Channel and includes sample stations from
Preesall Sands on the North Wharf and Middleton Sands and Sunderland Bank on the
Shoulder of Lune. The sample stations predominantly comprise muddy sand with
Arenicola marina and Cerastoderma edule varying in abundance between stations.
Plate 3.22
3.3.19
Littoral muddy sand with C. edule north of the Lune Channel
Transect BB: River Lune
Transect BB follows the edge of Calloway Marsh, an extensive area of saltmarsh on the
westward edge of the Lune Channel opposite the sewage works. Man-made river
training walls constructed with placed boulders have a covering of Enteromorpha sp.,
Fucus spiralis, Elminius modestus and Littorina litoralis.
At the sample stations where fine muds prevail, the sediment is largely devoid of
conspicuous macrofauna.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
Plate 3.23
3.3.20
Sheltered littoral rock biotope formed from the artificial training
walls of the River Lune
Transect CC: Cockerham Sands
Transect CC passes through Cockerham Marsh, a large area of predominantly Atlantic
salt meadow. Pioneer saltmarsh supports high numbers of Hydrobia ulvae and seaward
of this dense Enteromorpha covers an expanse of muddy sand. Within the muddy sand
of the final four stations on this transect, Corophium volutator is present in high
numbers.
Plate 3.24
Dense Enteromorpha covers an expanse of muddy sand at
Cockerham Sands
Intertidal survey of Morecambe Bay
and the Duddon Estuary
- 25 -
English Nature
February 2006
3.3.21
Transect DD: River Wyre
Comprising stations of fine mud, transect DD crosses the River Wyre from Little
Thornton to Hambleton. Stations are largely impoverished muddy sand backed by
grazed saltmarsh with occasional deep gullies. A cobble skear situated by Hambleton is
colonised by the barnacle Elminius modestus with interstitial fine mud anoxic at
approximately 2cm depth.
Plate 3.25
3.3.22
A cobble skear colonised by barnacles with interstitial fine mud
Transect EE: North Wharf, Fleetwood
The upper shore is a coarse sand/pebble matrix containing no conspicuous infauna.
The exposed North Wharf is largely rippled sand which varies in mud content.
Plate 3.26
Intertidal survey of Morecambe Bay
and the Duddon Estuary
Barren mobile sand, North Wharf
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English Nature
February 2006
3.3.23
Transect FF: Sandylands (2)
Joining the ends of transects Y and Z, Transect FF comprises sample stations in the
lower shore. The sediment at all stations is rippled muddy fine sand with Arenicola
marina.
Plate 3.27
A. marina casts on muddy sand, Sandylands, Morecambe
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006
4
DISCUSSION
The methodology adopted for the survey (i.e. a transect-based approach) has resulted
in a good overall spatial coverage of the extensive intertidal areas of Morecambe Bay
and the Duddon Estuary, with sampling undertaken at from the upper shore to the
lowest level of the shore possible at the time of survey.
A number of notable biotopes were recorded during the survey which could be
considered to be of particular conservation value, such as areas of Sabellaria reef,
eelgrass beds and mussel beds. In addition, extensive areas of Morecambe Bay were
characterised by cockles although the abundance of cockles was generally considered
to be low, possibly due to the very high intensity of cockle harvesting that is undertaken
in the Bay.
The vast majority of the intertidal area comprises fine sediments ranging from clean
sands through to sandy mud, with particularly sheltered areas being almost entirely
muddy sediment.
Intertidal survey of Morecambe Bay
and the Duddon Estuary
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English Nature
February 2006