Biological Survey of the Intertidal Sediments of the South Shore of the Solway Firth,

ladybugbazaarUrban and Civil

Nov 26, 2013 (4 years and 1 month ago)

189 views


Biological Survey of the

Intertidal Sediments of

the
South Shore of the

Solway Firth
,
2011



Report to

Natural England








Institute of Estuarine and Coastal Studies

University of Hull


May

20
11



Author(s):
N.D. Cutts,
K.L. Hemingway,
&
S
.

Thomson


Report:
Y
BB
170
-
F
-
20
11










Institute of Estuarine & Coastal Studies
(IECS)

The University of Hull

Cottingham Road

Hull

HU6 7RX

UK


Tel:
+
44 (0)1482 46
4120

Fax:
+
44
(0)1482 46
4130


E
-
mail:
iecs@hull.ac.uk


Web site:
http://www.hull.ac.uk/iecs







Natural England



Biological Survey of the
Intertidal Sediments of

the
South Shore of
the

Solway Firth
, 2011



May

20
11


Reference No:

YBB170
-
F
-
20
11








For and on behalf of the Institute of
Estuarine and Coastal Studies

Approved by:

N Cutts

Signed:


Position:

Deputy Director

Date:

06
-
05
-
11


This report has been prepared by the
Institute of Estuarine and Coastal
Studies, with all reasonable care, skill
and attention to detail as set within the
terms of the Contract with the client.


We disclaim any responsibility to the
client and others in
respect of any
matters outside the scope of the above.


This is a confidential report to the client
and we accept no responsibility of
whatsoever nature to third parties to
whom this report, or any part thereof, is
made known. Any such parties rely on
the

report at their own risk.









Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
i

Institute of Estuarine and Coastal Studies

EXECUTIVE SUMMARY

Background

T
he Solway
is
designated as a Special Area of Conservation

(
SAC
). A biotope survey was
undertaken by the Institute of Estuarine & Coastal Studies IECS on behalf of Natural

England (then English Nature) in the autumn of 2004, covering both north and south banks
of the Solway.


The current survey programme reported here covers some of the areas
surveyed in 2004 and as such provides information on the long
-
term status of habit
ats within
the SAC. T
he objectives of the
current
survey were
therefore
to report the following
information:



Extent of the infaunal communities as estimated from line transects.



Infaunal biotope richness (i.e. the number of biotopes).



Infaunal species div
ersity within the biotopes of highest conservation importance.



Sediment character (grain size, organic content, and depth of redox layer) along
transects, and relationship to observed changes in biological community.



Compare and contrast changes in extent
and type of biological communities and
sediment character within
previous

studies from the same area.

Methods

The survey programme was carried out at three sites; Old Graitney to Port Carlisle (Map 1);
Cardurnock Flatts and Grune Cast (Map 2); and Bitterless and Wolsty Banks (Map 3), with
the transect routes shown in these maps.
The sampling methodology and mappi
ng notation
followed the standard MNCR Phase 1 survey guidelines
e.g. as
detailed in Wyn
et al.

(2000a, 2000b), Wyn and Brazier (2001), and Dalkin and Barnett (2001)
. B
iotope
assignation
was based on the
National Marine Habitat classification version
04.0
5

(Connor
et al
., 2004). Deployment occurred on the 15
th

March 2011 and the survey work was
undertaken on 16
th

to 18
th

March 2011 inclusive. Cardurnock to Grune Point was surveyed
on the 16
th

March, following the identification of a revised launch locati
on, Silloth to Dubmill
was carried out on the 17
th

March and Gretna to Port Carlisle on the 18
th

March 2011.

Old Graitney to Port Carlisle

This extreme upper estuarine area includes two freshwater input channels into the Solway

Firth
, i.e. the River Esk
to the north of Rockcliffe Marsh, and the River Eden to the south of
the marsh.
Between these two channels, in the extreme upper part of the system, is an
area of high marsh. Fronting the marsh is an extensive area of intertidal soft sediment,
including
areas of high sand bank and extensive low sand flats which are present in both the
Eden (e.g. around Burghmarsh Point) and Esk (e.g. around Redkirk Point) branches
(adjacent to the freshwater channels, and around the confluence of these channels (e.g.
upst
ream from around Torduff Point to Port Carlisle). Three main intertidal soft sediment
habitats were identified within the area (in addition to high saltmarsh):



Large elevated fine to medium fine sand flats;



Extensive flat low shore firm rippled muddy sand

to fine sand flats;



Relatively narrow sandy mud with occasional cobble on the fringing banks.



Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
ii

Institute of Estuarine and Coastal Studies

Cardurnock Flatts to Grune Cast

Cardurnock Flatts is an extensive area of intertidal sandflat in the Inner Solway, to the south
of the main Eden Channel

(and b
ounded by the channel in its northern and eastern extent)
.
The southern area of the site features several cobble scars, these being situated around the
mouth of Moricambe Bay
, a large coastal inlet. To the south of this inlet lies the coastal
feature Gru
ne Point, with an intertidal area extending out to its west (Grune Cast). Offshore
from this location by
c.
1km is Middle Bank, which forms an extensive mobile mid channel
sand bank.

The

survey
identified
two main intertidal soft sediment habitats (in
addition to
high saltmarsh):



Extensive flat low to middle shore firm rippled muddy sand to fine sand flats;



Low shore soft sediment ‘delta’ formed by the discharge from Moricambe Bay.

In addition, cobble/boulder habitats were present both in the form of in
tertidal scar areas and
in the upper
-
shore along the southern section of Grune Point. These habitats featured a
variable associated fauna, from absence to a relatively abundant barnacle and littorinid
community.

Bitterless and Wolsty Banks

The
intertidal
reach
running south (downstream)
from Silloth to
Dubmill Point

features
extensive intertidal sandflats backed by a significant dune complex.

The intertidal sandflats
incorporate areas of scar and boulder field, the status of these being
apparently
relativ
ely
ephemeral depending on erosion and deposition cycles.

The survey concentrated on the
intertidal area fronting the Blitterlees Bank to Wolsty Bank area.

Three main intertidal soft sediment habitats were identified within the area (in addition to
high s
altmarsh):



Extensive flat low to middle shore firm rippled muddy sand to fine sand flats;



Scar ground of variable coverage and faunal diversity (inc. boulder fields);



Biogenic reef with
Mytilus

and
Sabellaria

communities present.

In general, the soft sedim
ent habitats of the survey area were found to be relatively
impoverished during the survey. However, this is considered partly to be an artefact of
survey timing, although the 2004 survey also recorded a relatively impoverished soft
sediment infauna.

Deta
ils of the biotopes recorded from the surveys and their distribution are included in the
main text, as well as in accompanying maps.

Conclusions

In general, the 2011 survey recorded a similar biotope assemblage to that of the 2004
survey programme, with lo
cation and extent of biotopes (where comparison is possible)
broadly consistent across the two surveys, with species richness generally poor from both
surveys. However, some differences in extent and dominance of communities was noted,
reflecting differen
ces in survey timing, as well as a possible small shift in community
composition.

The biogenic reef area to the south of Lees Scar was recorded both in 2004 and 2011,
consisting of cobble and fine sediment together with
Mytilus

and
Sabellaria
, the latter

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
iii

Institute of Estuarine and Coastal Studies

partially smothered by pseudo
-
faeces and in a generally poor condition. However, it would
appear from the distribution data that this area has extended from the 2004 survey, in
particular to the south.

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
iv

Institute of Estuarine and Coastal Studies

TABLE OF CONTENTS


E
XECUTIVE
S
UMMARY

................................
................................
................................
..............

I

T
ABLE OF
C
ONTENTS

................................
................................
................................
.............

IV

1.

I
NTRODUCTION

................................
................................
................................
...................

1

1.1 Background

................................
................................
................................
..............

1

1.2 Survey Aims and Objectives

................................
................................
....................

1

1.3 Solway Firth Estuary

................................
................................
................................

1

1.3.1 Conservation Designations

................................
................................
...........

3

1.3.2 Biology

................................
................................
................................
.........

5

2.

M
ETHODOLOGY

................................
................................
................................
..................

9

2.1 Pre
-
Survey Work

................................
................................
................................
......

9

2.2 Intertidal Survey

................................
................................
................................
.....

11

3.

R
ESULTS

................................
................................
................................
.........................

16

3.1 Old Graitney (North Bank) to Port Carlisle (South Bank)

................................
........

16

3.1.1 Overview

................................
................................
................................
....

16

3.1.2 Habitat Description

................................
................................
.....................

18

3.2 Cardurnock Flatts and Grune Cast

................................
................................
.........

24

3.2.1 Overview

................................
................................
................................
....

24

3.2.2 Habitat Description

................................
................................
.....................

25

3.3 Bitterless and Wolsty Banks (south of Silloth)

................................
........................

33

3.3.1 Overview

................................
................................
................................
....

33

3.3.2 Habitat Description

................................
................................
.....................

35

4.

C
ONSERVATION
A
SSESSMENT
&

D
ISCUSSION

................................
................................
....

46

4.1 Comparison with Previous Surveys

................................
................................
........

46

4.1.1 Intertidal Soft Sediment Flats

................................
................................
......

46

4.1.2 Biogenic Reefs and Scar Grounds

................................
..............................

47

4.2 Disturbance to Avifauna from Hovercraft Operation

................................
...............

47

5.

C
ONCLUSIONS AND
R
ECOMMENDATIONS

................................
................................
...........

49

6.

R
EFERENCES

................................
................................
................................
...................

50

A
PPENDICES

Appendix 1: Species Abundance

Appendix 2: Loss on Ignition Data

Appendix 3: PSA Data


Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
1

Institute of Estuarine and Coastal Studies

1.
INTRODUCTION

1.1 Background

One of the key responsibilities of the statutory nature conservation agencies in the UK is the
identification and pr
otection of a series of sites intended to conserve important wildlife and
Earth science features. Such sites may be designated under national legislation
(
e.g.

Sites
of Special Scientific Interest

(
SSSIs
)
), or European legislation

such as

Special Areas of

Conservation
(
SACs
)

under the Habitats Directive
1
,

and
Special Protection Areas (
SPAs
)

under the Birds Directive
2
. Regular monitoring of sites
is undertaken in order to assess the
effectiveness of legislative and policy measures in contributing to biodiv
ersity conservation
.
The intertidal mudflats and sandflats are an acknowledged interest feature in the
designations of the Solway Firth estuary
,

and as such, the survey reported here has
aim
ed

to

provide data to support the overall monitoring programme of the site. Ultimately, the data
will form a part of the
ongoing
condition assessment for the site.


1.2 Survey Aims and Objectives

T
he Solway
is
designated as a Special Area of Conservation

(
SAC
),
and
the current study
therefore
form
s

part of a long term monitoring programme being jointly administered by
Natural England (NE)
, and Scottish Natural Heritage (SNH) under the requirements of the
Habitats Directive

(and enabling UK legislation)
.

A sim
ilar type of survey was undertaken by
IECS on behalf of Natural England (then English Nature) in 2005, although this survey
covered both north and south banks of the Solway.

The current survey programme was to undertake intertidal biotope mapping work on t
he
south shore of the Solway (survey effort and platform prescribed in the project specification).
T
he objectives of the survey defined under the project specification were
therefore
to report
the following information:



Extent of the infaunal communities
as estimated from line transects.



Infaunal biotope richness (i.e. the number of biotopes).



Infaunal species diversity within the biotopes of highest conservation importance.



Sediment character (grain size, organic content, and depth o
f redox layer) along
t
ransects, and relationship to observed changes in biological community.



Compare and contrast changes in extent and type of biological communities and
sediment character within
previous

studies from the same area.


1.3

Solway Firth Estuary

The Solway Firth

(Figure 1) is a macrotidal estuary situated on the west coast of Britain
which represents one of the largest tidal embayments in the north eastern Irish Sea. The



1

Council Directive 92/43/EEC of 21 May 1992 on the
C
onservation of
N
atural
H
abitats and of
W
ild
F
auna and
F
lora

(commonly referred to as the ‘Habitats Directive’)
.

2

Council Directive 79/409/EEC of 2 April 1979 on the Conservation of Wild Birds

(commonly referred to as the
‘Birds Directive’).

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
2

Institute of Estuarine and Coastal Studies

southern shoreline of the estuary is located in England along the Cumbrian coast, whilst the

northern shoreline lies in Scotland along the Dumfries and Galloway coast. The estuary is a
tidally flooded synclinal feature with inputs from a number of rivers (including the Esk, Eden,
Annan, and Nith), giving an average fluvial input in excess of 100

cumecs (Babtie
et al
.,
1966). In extreme flood and drought conditions, this may fluctuate between 3,400 cumecs
and 7.4 cumecs respectively (Babtie
et al
., 1966).


Figure 1: The Solway Firth.

Within the estuary,

the tidal range using mean low

and high water spring tides at
Kirkcudbright Bay

is approximately 6.7
m, whilst at Silloth on the Cumbrian coast, this
increases to 8.4 m. However, further upstream at Redkirk (near the head of the estuary), the
spring tide range is reduced to approximat
ely 3.6 m, and at this point, tidal height is also
significantly influenced by inputs from the River Esk. The estuary additionally features
strong tidal currents, with a maximum speed of up to 4 knots during spring tides, and more
than 2 knots during neap

tides (as derived from the Admiralty Chart tidal diamond for the
area). Under certain conditions, a tidal bore may form upstream of Annan, with a speed of
approximately 6 knots, and a height in extreme conditions of 1.5 m (ABP, 1991).

Wave height and dir
ection is largely dependent on the aspect and fetch, and the enclosed
nature of the Irish Sea means that the Solway is genera
l
l
y

sheltered from Atlantic swells,
with fetch lengths between 200
-
300 km (although the Isle of Man reduces this to under 100
km).

The prevailing winds for the outer Solway are from the north
-
west in winter, and south
-
west in summer (Babtie
et al
., 1989), although a degree of channelling occurs in the upper
estuary, with prevailing winds from the south
-
west quadrant recorded

at Chape
lcross
throughout the
year (Ove Arup & Partners, 1993a, 1993b).

The mudflats and sandflats of the Solway comprise the third largest continuous area of mud
and sand in the UK after the Wash and Morecambe Bay (Davidson
et al
., 1991), with
intertidal flats co
vering an area of over 35,000 ha, and accounting for 50% of the total area
Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
3

Institute of Estuarine and Coastal Studies

of the Inner Solway (SSMA, 2004). They contribute significantly to the habitat diversity of
the site, and this environmental importance is reflected in its many nature reserves and

conservation designations (Section 1.3.1). The intertidal flats are highly mobile and
predominantly consist of fine sands and silt, with fine sandy sediments occurring in the inner
estuary, and coarser sediments in the outer reaches. The presence of fin
e sands rather
than muds (due to the lack of mud being imported into the system from rivers) is unusual in
conditions of estuarine salinity, although a typical estuarine fauna is supported, with the
dominant infauna dependant on variation in sediment compo
sition and position on the shore.
As such, the flats provide a valuable food source for feeding birds and fish as well as acting
as a refuge site for roosting birds.

In general, sediment deposits within the sandbanks of the Solway are of a coarser nature
than those found in most estuaries, with a mean grain size of approximately 100
µ
m (Black
et al.
, 1994). Material in the inner estuary is mainly composed of smaller grain sizes (with
the flats associated with the River Nith and the Nith estuary having an
average particle size
of <63
µ
m, thereby being classified as silt or clay), whilst in general, the outer estuary has a
coarser sediment type (Black
et al
., 1994). Material >2 mm is uncommon in the estuary, and
the majority of coarse deposits (including pe
bble, cobble, and boulder), are associated with
eroded glacigenic deposits, although shell debris may occur. These areas range from
shingle and/or pebble beaches to cobble/boulder scars, and generally occur as a result of
erosion of glacial material backi
ng the site, with the larger material (by virtue of its size),
remaining close to the parent source (Cutts & Hemingway, 1996). The majority of these scar
grounds are located in the inner estuary close to Powfoot, and are associated with the
glacial and fl
uviglacial material of that area.
However, e
xtensive areas of scar
also

occur on
the south shore between Silloth and Maryport, with this material being eroded from raised
shingle structures under the dunes, or removed from the offshore scar grounds and ca
rried
landwards by storm waves (Cutts & Hemingway, 1996).

The biotope survey undertaken by IECS in 2005 (Hemingway
et al
, 2006), confirmed much
of the above, with the findings also consistent with previous IECS studies of the area.
However, the study did
identify specific examples of the dynamic nature of the soft sediment
habitats within the estuary, with the presence/absence of scar grounds not always consistent
with those described historically, from previous IECS studies, and from Ordnance survey
maps
and associated aerial photographs. This variability was noted on the north shore
around Powfoot, and of relevance for the current study, around the mouth of Moricambe Bay
and along the Silloth to Dubmill reach.

1.3.1

C
ONSERVATION
D
ESIGNATIONS

The environ
mental importance of the Solway Firth is reflected through a wide variety of
statutory and non
-
statutory international, national, and local mechanisms which opera
te
within the estuary (Table 1)

to conserve and protect its wildlife (SSMA, 2004). The estuar
y is
of particular importance in terms of avifaunal abundance, and is home to an average of
110,000 overwintering waterfowl each year (Quinn
et al
., 1997). As a result, the Inner
Solway has been designated a wetland of international importance under the R
amsar
Convention
3
, and a Special Protection Area (SPA) under the Birds Directive. Similarly, the
Inner Solway has been designated as a Site of Special Scientific Interest (SSSI) notified



3

The Convention on Wetlands of International Importance especially as
Waterfowl Habitat (commonly referred to
as the ‘RAMSAR’ Convention).

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
4

Institute of Estuarine and Coastal Studies

under the Wildlife & Countryside Act 1981
4

(as amended), and a
Special Area for
Conservation (
SAC) under the EU Habitats Directive (SSMA, 2004).

All candidate SACs in Scotland were approved by the European Commiss
ion as
Sites of
Community Importance
(
SCIs
)

on 7 December 2004
,

and subsequently formally designated
as
Special Areas of Conservation

by
Scottish Ministers on 17 March 2005

(Scottish Natural
Heritage, 2006)
.

The Solway Firth was included in this formal SAC designation (total area of
43687.99

ha)
based on the following
notified features:
Atlantic salt meadow
s
;
c
oastal shingle
vegetation outside the reach of waves
;
d
une grassland
;
e
stuaries
;
G
lasswort and other
annuals colonising mud and sand
;
i
ntertidal mudflats and sandflats
;
r
eefs
;
River lamprey
(
Lampetra fluviatilis
)
;
Sea lamprey (
Petromyzon marinus
)
, and
s
ubtidal sandbanks

.

Table 1: Statutory and Non
-
statutory conservation designations for wildlife in the Solway Firth
(Solway Firth Partnership, 1996; SSMA, 2004).

S
ITE
N
AME

G
RID
R
EF
.

A
PPROX
A
REA
(
HA
)

S
TATUS

S
UMMARY OF
Q
UALIFYING
S
PECIAL
F
EATURES

S
TATUTORY
C
ONSERVATION
D
ESIGNATIONS

Upper Solway Flats
and Marshes

includes
:


Caerlaverock

NY 160610




NY005603

29,951




7,710

SSSI, Ramsar
site, SPA, SAC,
NCR/GCR


S
S
SI, Ramsar,
NNR, SPA,
Biosphere reserve

Geomorphology, saltmarsh
, subtidal
flats, wintering waterfowl, breeding
birds, natterjack toads, invertebrates,
and flowering plants. Regularly
supports over 20,000 water birds

Royal Ordnance,
Powfoot

NY 165567

37

SSS
I

Amphibians

Silloth Dunes and
Mawbray Bank

NY 105525

188

S
SSI

Sand dunes, dune heath, flowering
plants, natterjack toads

Wigtown Bay and
the Cree estuary

NX 465545

3,475

cRamsar, cSPA,
LNR, SSSI

Intertidal flats, pink
-
footed geese,
saltmarsh, mudflats, wintering
waders/geese, flowering plants, rare
fish species

Bay Bay to
Carghidown

NX 400367

237

SSSI, GCR

Geology, coastal habitats, flowering
plants, breeding birds

Lower River Cree

NX 413649/

NX 448619

156

SSSI

Rare fish

Borgue Coast

NX 610457

749

SSSI, NCR/GCR

Maritime heath, machair, seabirds,
geology

Torrs

to Mason’s
Walk

NX 710437

168

SSSI, GCR

Coastal habitats, flowering plants,
geology

Abbey Burn Foot to
Balcary Point

NX 790469

186

SSSI

Coastal habitats, flowering plants,
seabirds

Auchencairn Bay
and Orchardton Bay

NX 809517/

NX 818532

179

SSSI

Saltmarsh, mudflats

Port O’Warren

NX 876534

6

SSSI

Breeding birds




4

This legislation is the means by which the Convention on the Conservation of European Wildlife and Natural
Habitats (the 'Bern Convention') and the European Union Directives on the Con
servation of Wild Birds
(79/409/EEC) and Natural Habitats and Wild Fauna and Flora (92/43/FFC) are implemented in Great Britain.

It
does not extend to Northern Ireland, the Channel Islands or the Isle of Man.

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
5

Institute of Estuarine and Coastal Studies

Table 1 cont.

S
ITE
N
AME

G
RID
R
EF
.

A
PPROX
A
REA
(
HA
)

D
ESIGNATIONS

N
ON
-
STATUTORY
N
ATURE
R
ESERVES

Rockcliffe, Dumfries

NX 845541

48

NTS reserve

Mersehead

NX 92 56

743

RSPB reserve, SPA, Ramsar,
SAC, part SSSI

Campfield Marsh

NY 195616

221

RSPB reserve, SPA, Ramsar,
SAC, part SSSI

East Park Reserve,
Caerlaverock

NY 051657

726

WWT reserve
, NNR, part SSSI, SPA, Ramsar,
SAC

Southwick Coast

-

3

SWT re
serve, part SSSI, SPA, Ramsar,
SAC

Drummains
Reedbeds

NX 98 60


SWT re
serve, part SSSI, SPA, Ramsar,
SAC

Rockcliffe Marsh

NY 340637

1,120

SSSI,
SAC, SPA, private reserve (CWT monitored), Ramsar

Bowness
-
on
-
Solway

NY 207618

6

CWT reserve

Kirkconnell
Merse

NX 986685

243

RSPB rese
rve, SPA, Ramsar,
SAC

K
EY
:

SSSI (Site of Special Scientific Interest); NNR (National Nature Reserve); SAC (Special Area of Conservation);
SPA (Special Protection Area); GCR (Geological Conservation Review site); NCR (Nature C
onservation Review site);
LNR (Local Nature Reserve); NNR (National Nature Reserve); NTS (National Trust for Scotland); WWT Reserve
(Wildfowl and Wetlands Trust Reserve); RSPB Reserve (Royal Society for the Protection of Birds Reserve); SWT
Reserve (Scotti
sh Wildlife Trust Reserve); CWT Reserve (Cumbria Wildlife Trust Reserve).


1.3.2

B
IOLOGY

1.3.2.1 Invertebrates

The nature of communities present within the intertidal flats depends on a
variety

of factors
,

including

sediment type (grain size/silt content), shore height, exposure to wave action, and
salinity
, with further variation occurring on a seasonal basis
. In areas where there is
considerable freshwater input, only a few tolerant brackish species persist. Howe
ver,
although estuarine species diversity may be low, individual species are often present in
extremely high abundances. In the Solway, up to 20,000 burrowing amphipods, and 20,000
surface dwelling gastropods may be found per square metre (Solway Firth Pa
rtnership,
1996).

Towards the head of the Firth, sediments
have been described as

dominated by muddy silt
with varying degrees of sand content (Covey & Emblow, 1992; Cutts & Hemingway, 1996).
Typical species in these areas include polychaetes such as
Hediste

diversicolor

(ragworm
),
burrowing bivalves (i.e.
Macoma balthica

-

B
altic tellin
), and
Cerastoderma edule

(common
cockle
)
.
Talitrus saltator

(
sandhopper
)
, together with
Hydrobia ulvae

(laver spire shell
) also
tend to be common on the sediment surf
ace (Cutts & Hemingway, 1996).

In areas of fine or very fine sand under normal salinity conditions, typical species often
include polychaetes such as
Nephtys
spp.,
Scoloplos armiger
,
Arenicola marina

(lugworm
),
and the amphipod

Bathyporeia pelagica

(SSMA,
2004), whilst a
reas influenced by
freshwater run
-
off are dominated by oligochaetes. In contrast, coarse sediments occur in
areas of high wave exposure and in these areas, the fauna is dominated by burrowing
amphipods, mainly
Bathyporeia
species (Cutts & H
emingway, 1996). Clean medium sands
to fine sands in moderately exposed reaches of the Firth are dominated by polychaetes such
as
Nephtys cirrosa
and
Nephtys hombergii,
together with

bivalves

such as

Angulus tenuis
(
t
hin tellin)
and
Donax vittatus

(
b
anded

wedge shell)
. Transitional communities occur with
changes in grain size (Covey & Emblow, 1992).

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
6

Institute of Estuarine and Coastal Studies

Intertidal scar ground mapping
undertaken
on the northern shore of the Solway (Allen
et al
.,
1999), found the main scar ground biotopes recorded during the su
rvey related to mid
-
upper
shore areas. These scar grounds (Powfoot, Howgarth, Hogus Point, Nethertown, and
Rough) were found to be dominated by a pebble/cobble substratum with interstitial muds,
surrounded by extensive mud and sand flats. Wave exposure w
as low to moderate, and
dominant species included
Mytilus edulis

(
c
ommon mussel), and
Elminius modestus

which
occurred in variable levels of abundance.
Semibalanus balanoides

were also observed on
occasion, although these barnacles were not
found to be
as

common as
E. modestus
.
Littorinids were
observed

in relatively high densities on both the cobble and soft substratum,
and
Carcinus maenas

(common shore crab
)

was present
beneath

boulders and in pools.
Additional scar grounds were described for the south

shore of the Solway in Hemingway
et
al
2006.

In general,
f
ucoid cover on the scars was found to be limited, although extensive areas were
noted at Powfoot, whilst
Ulva

lactuca

(sea lettuce)
and
Enteromorpha

sp. were occasional at
most sites. A soft subst
ratum (predominantly sandy mud) was found both interstitially within
mussel beds
,

and between cobbles and pebbles, forming small pans in some areas. These
areas supported locally abundant to common populations of
C. volutator

and
H. ulvae
,

together with polychaetes including
H
.

diversicolor
, and bivalves such as
M. balthica

and
Scrobicularia plana

(
peppery furrow shell
)

(Allen
et al
., 1999).

The Marine Nature Conservation Review (MNCR) have identified a number of characteristic
and returning

species from within a variety of sediment types, and a fuller description of
these are given by Connor
et al.

(1997, 2004).

1.3.2.2 Fish

The Solway supports a wide range of fish species, the most common being plaice, dab,
whiting, pogge, sand goby, and f
lounder (Lancaster, 1999). Other species identified from
beam trawls in the estuary (Lancaster
, 1999) include

lesser weever, sprat,
D
over sole, cod,
sand eel, snake pipefish, seasnail, five
-
bearded rockling, grey gurnard, pollock, red gurnard,
deep
-
snoute
d pipefish, thornback ray, herring, lesser
-
spotted dogfish, salmon, three
-
bearded rockling, brill, transparent goby, smelt, dog fish, dragonet, bib, haddock, butterfish,
and sea lamprey.

The estuary is used as a nursery area by a number of juvenile fish
species and as such, it is
of regional value in the Irish Sea context. Similarly, it is an important area for migratory fish
such as salmon and sea trout which migrate into the rivers of the Nith, Annan, Sark, Kirtle
Water, Esk, Eden, and Derwent. The ra
re allis shad (
Alosa alosa
), twaite shad (
Alosa
fallax
), and river lamprey
(Lampetra fluviatilis
), also migrate through the estuary to breeding
grounds (Solway Firth Partnership, 1996). It is possible that allis shad may breed in the
estuary itself althou
gh at present, there is no clear evidence of spawning stocks (Allen
et al
.,
2003). The allis shad, twaite shad,
Atlantic

salmon, and sparling, have all been identified as
priority species by the Dumfries and Galloway Coastal and Maritime Biodiversity Acti
on
Group (SSMA, 2004).

1.3.2.3 Avifauna

The estuary supports nationally and internationally important numbers of migrating and
wintering waterfowl, and regularly supports peak counts of more than 110,000 birds (Quinn
et al
., 1997). Both the size and loca
tion of the estuary ensure that the Solway is a vital
resting and wintering area for birds migrating along the eastern Atlantic seaboard by
Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
7

Institute of Estuarine and Coastal Studies

providing productive feeding grounds (Solway Firth Partnership, 1996). The Inner Solway
supports internationally im
portant numbers

of eleven species
(including the entire Svalbard
population of Barnacle geese), and a further nine species are present in nationally important
numbers (Table 2). Wigtown Bay is of international importance in its own right for wintering
Who
oper swans and Pink
-
footed geese. In addition, the areas of saltmarsh associated with
the estuary, particularly Caerlaverock and Rockcliffe, support varied breeding bird
populations. The Inner Solway is therefore important for birds throughout the year (
Solway
Firth Partnership, 1996).

N
ationally important breeding sea
-
bird colonies are located at the Mull of Galloway, Scare
Rocks, St. Bees Head, and Almorness, whilst regionally important colonies occur at
Burrowhead, Portling, and Balcary Point. Althoug
h these birds are only associated with land
during the short breeding season (spending the rest of their life entirely at sea), the outer
Solway holds important populations of several seabird species throughout the year (Solway
Firth Partnership, 1996). T
able 2 shows the distribution of waterfowl in the Solway during
2000
-
2001 which is the most recently published data available for the area using the annual
Wildfowl and Wader (WeBS) counts.

Table 2: Distribution of waterfowl in the Solway Firth (Dumfries
& Galloway/Cumbria) during
2000
-
2001 (data from Pollitt
et al
., 2003).

S
PECIES

D
ISTRIBUTION

I
NTERNATIONALLY IMPOR
TANT

Whooper swan

Small numbers of Whooper Swan frequently observed in the inner part of the
estuary.

Pink
-
footed Goose

Although Pink
-
footed geese typically use estuaries as nocturnal roosts, those
present during the Solway low tide counts favoured Moricambe Bay.

Barnacle Goose

Numbers peaked at more than 7,000 in November, with birds being concentrated
along the flats of
the River Nith, on Mersehead Sands, and around Glasson.
However, these numbers were significantly below the 23,000 birds observed during
dedicated goose counts at the site.

Shelduck

Concentrated within Moricambe Bay, with lesser numbers off Overton, and
to the
east of Powfoot.

Pintail

Predominantly found in the middle sections of the estuary, with smaller numbers at
the mouth of the Nith, Powfoot, and off Skinburness.

Oystercatcher

Widely distributed, although absent from the extreme eastern mudflats.

Knot

Large concentrations on the flats off Carsethorn, Seafield, and adjacent to the
mouth of the Annan. Other important areas included the mudflats south of
Caerlaverock, and the area between Grune Point and Bowness
-
on
-
Solway.

Dunlin

Concentrations on
the flats off Carsethorn, Seafield, and adjacent to the mouth of
the Annan. Other important areas included the mudflats south of Caerlaverock and
the area between Grune Point and Bowness
-
on
-
Solway. Greatest concentrations
located at the eastern end of th
e Solway.

Bar
-
tailed Godwit

Predominantly recorded at low tide on the flats of Grune Point.

Curlew

Widely distributed throughout the Solway, with the greatest densities in Moricambe
Bay and at the eastern end of the estuary.

Redshank

Concentrated within

the inner part of the estuary, including Moricambe Bay, with
smaller concentrations between Southerness Point and Overton.

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
8

Institute of Estuarine and Coastal Studies

Table 2 cont.

S
PECIES

D
ISTRIBUTION

N
ATIONALLY IMPORTANT

Great Crested Grebe

Predominantly in the outer estuary.

Cormorant

Frequently observed in the inner areas of the estuary.

Scaup

Typically concentrated between Carsethorn and Southerness Point (flock
containing over 1,800 birds).

Common Scoter

Recorded (location not specified).

Red
-
breasted Merganser

Recorded (location
not specified).

Ringed Plover

Small numbers observed predominantly in Moricambe Bay.

Golden Plover

Concentrated on Moricambe Bay, and the eastern end of the Solway from Powfoot
to Torduff Point on the northern side.

Grey Plover

Preference for the area
between Grune Point and Bowness
-
on
-
Solway, with a few
birds present off Carsethorn Point.

Black
-
tailed Godwit

Moricambe Bay and the flats off Torduff Point.

O
THER


Red
-
throated Diver

Recorded (location not specified).

Black
-
throated Diver

Recorded
(location not specified).

Grey Heron

Recorded (location not specified).

Mute Swan

Recorded (location not specified).

Greenland White
-
fronted
Goose

Recorded (location not specified).

Greylag Goose

Although Greylag geese typically use estuaries as nocturnal roosts, those present
during the Solway low tide counts favoured Moricambe Bay.

Wigeon

Favoured Moricambe Bay

and the flats off Skinburness, with smaller numbers in
the inner part of the estuary, and at the mouth of the Nith.

Gadwall

Recorded (location not specified).

Teal

Favoured Moricambe Bay and the flats off Skinburness, with smaller numbers in
the inner p
art of the estuary, and at the mouth of the Nith.

Mallard

Predominantly found within Moricambe Bay and the inner part of the estuary.

Shoveler

Recorded (location not specified).

Tufted Duck

Recorded (location not specified).

Red
-
breasted Merganser

Recorded (location not specified).

Goosander

Recorded (location not specified).

Moorhen

Recorded (location not specified).

Lapwing

Concentrated in Moricambe Bay and adjacent to Bowness
-
on
-
Solway on the
southern side, and the eastern end of the Solway fr
om Powfoot to Torduff Point on
the northern side.

Purple Sandpiper

Small numbers off Southerness Point.

Turnstone

Small numbers off Southerness Point, Carsethorn, and Powfoot.

Kingfisher

Recorded (location not specified).

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
9

Institute of Estuarine and Coastal Studies

2. METHODOLOGY

2.1
Pre
-
Survey Work

Prior to undertaking the survey work
,

desk
-
based analysis and preparation was undertaken.
The desk study involved the analysis of aerial photographs and maps (provided by
Natural
England
), together with other data pertaining to the study a
rea. The aerial photographs
were
input into GIS and overlain on OS base maps.
Analysis of survey work results from the 2005
programme (Hemingway
et al

2006) was carried out in order to both ensure a degree of
comparability between studies, but to also en
sure that additional data were collected from
areas previously un
-
surveyed.

Importantly for this survey programme, the study would be wholly based from a hovercraft
survey platform. The use of a hovercraft was employed by IECS in the 2005 programme,
and i
t proved to be an extremely valuable tool, both in terms of general Health & Safety
provision (in an area prone to patches of soft sediment, extensive channel banks and
rapid
tidal inundation), and in terms of survey coverage, allowing very large areas of
tidal flat to be
surveyed. However, a hovercraft has operational constraints and in particular, cannot be
operated in strong or gusty winds. Furthermore, where long distance operation and a
potential for water transit is required, then even moderate wind

speeds have to be taken into
consideration where wind against tide might create choppy conditions.
This can constrain
survey operations.

Prior to commencement of the fieldwork, optimum survey periods on spring tides were
identified in order to maximise s
afe working time in the intertidal zone (to low water). Tidal
data for the area was derived from UKHO TotalTide
TM

tide prediction software
. However,
due to
craft
availability and weather conditions, potential windows during the autumn
of 2010
proved to
be untenable
. Operations were then further constrained by
working daylight
limitations and tide state during the winter, with spring tides tending to occur with high water
around midday.
Given the issues associated with spring tide deployments, s
everal s
urvey
opportunities were identified under mid neap:spring conditions, but these had to be
cancelled due to the weather.
In particular, t
he early winter programme was affected by the
prolonged cold spell which entailed a statutory wildfowling ban on the Sc
ottish shore of the
estuary and a voluntary ban elsewhere in the estuary, whilst in the late winter, a series of low
pressure systems created prolonged changeable gusty conditions during suitable working
periods. As such, the survey was finally undertaken

in the early spring of 2011

during mid
neap
-
spring conditions. These were perhaps not ideal in terms of tidal exposure to the
extreme low water mark, but high water timing (usually mid to late morning) together with
increasing daylight hours, allowed sur
vey work to be carried out safely into the early
evening, thus increasing operational survey time compared to the mid winter period.

The priority areas to be surveyed were established
at the tender stage with Natural England,
with a contract specification
indicating 3 working days of hovercraft based survey. As such,
3 survey areas were identified within the Solway, the areas considered to both be largely
comparable to those surveyed in 2005, but with additional survey area potential, and which
could be ac
cessed safely by hovercraft.

These survey areas are shown in Figure
2
, and
cover the extreme inner estuary (Gretna to Port Carlisle), inner Solway (Cardurnock to
Grune Point), with an alternative area of Moricambe Bay if the wind was likely to constrain
o
peration on the outer mudflats
,

and the middle estuary/open coast from Silloth down to
Dubmill Point.

The actual survey tracks undertaken during the march survey are shown in
Maps 1


3, including transect and point numbers.

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
10

Institute of Estuarine and Coastal Studies


Extreme inner Solway survey
areas: (Gretna to Port Carlisle)
and Cardurnock Flatts to Grune
Point.

An alternative location was
identified within Moricambe Bay
which could be used if wind
conditions proved to be
unacceptable on the more
exposed outer flats (Area
shown in pink)


Middle Solway survey area:
Silloth to Dubmill Point.

Figure
2
: Proposed survey areas

and notional transect routes

Permissions for access were sought by IECS
. These included contacting the Port of Silloth
Harbour Master for permissions to operate in the Silloth approaches and in determining
access onto Grune Point.

This latter site was used to mobilise and demobilise the hovercraft
during the 2005
programme
, but access issues were identified (a locked gate) and
it was necessary for
a key
to be

sought

when ‘in the field’
.

For the 2011 survey it was planned to use the same site to
launch the hovercraft and
to reduce risk,
access details and a key
-
holder

were
determined in
advance (a new key owner identified). However on arrival at the site, it was found that a
barbed
-
wire fence had been erected around the outer edge of Grune Point, constrain
ing

hovercraft access on and off the beach. As such, it was necessar
y to locate a different
launching site to cover the Cardurnock area. Although a potential access was available
south of the Port of Silloth, this would entail considerable transiting over water (with little or
no intertidal area available as a

safe haven

) and the hovercraft operator considered this
inappropriate, particularly as during the return leg, access would be
during conditions where
wind
would be
against tide and
transit to the recover point would have to be made against
the direction of the tide
.
An alternative
launch
location was
therefore
identified at
Skinburness, consisting of a concrete ramp over the coastal defences and onto the upper
shore. Although this was not considered ideal due to the amount of cobbles at the
seaward
foot of the ram
p, it was considered to be safe for use by the hovercraft operator.

Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
11

Institute of Estuarine and Coastal Studies

Necessary operational information was also provided to the MCA (Liverpool) on the start and
completion of each survey.

2.2 Intertidal Survey

This stage involved the

in situ
field survey
ing and mapping of the soft sediment habitats of
the intertidal zone of the study area as identified in Figure
1
, and in accordance with the
agreed survey schedule.

Details of the actual survey paths for each of the survey areas are
given in Maps 1 to 3, which also show transect and sample points.

The survey of Old Graitney to Port Carlisle (Map 1) was curtailed by a small tidal bore
arriving within the survey area t
owards the end of the outward transect. Additional transects
were possible however on the upper shore and further upstream in the low shore on the
return route. As such, the return route transect start a
n
d end does not correspond to a start
and end of a
biotope, but rather to the extent of tidal inundation at that time, with the area
rapidly being covered by the tide.

Similarly, the return route of Cardurnock Flatts and Grune
Cast
(Map 2)
includes transect gaps where the incoming tide had covered the low

water
boundary of the channels.

Map3 shows the survey route for Bitterless and Wolsty Banks.

The sampling methodology and mapping notation followed the standard MNCR Phase 1
survey guidelines detailed in Wyn
et al.

(2000a, 2000b), Wyn and Brazier (2001),

and Dalkin
and Barnett (2001) from the Marine Monitoring Handbook (Davies
et al
., 2001), together with
the MNCR/Biomar reports such as Hiscock (1996), and Connor
et al.

1997.
B
iotope
assignation
was based on the
National Marine Habitat classification ver
sion
04.05

(Connor
et al
., 2004).

Deployment occurred on the 15
th

March 2011 and the survey work was undertaken on 16
th

to 18
th

March 2011 inclusive. Cardurnock to Grune Point was surveyed on the 16
th

March,
following the identification of a revised launc
h location, Silloth to Dubmill was carried out on
the 17
th

March and Gretna to Port Carlisle on the 18
th

March.

Transects were undertaken using the hovercraft through a series of representative habitats
(as identified from aerial photographs and maps whe
re possible). However some
operational constraints for the hovercraft (e.g. cobble ground, creek systems and sand
waves meant that not all areas could be covered.

WGS84 was used as the coordinate
system for the survey

with transect tracks plotted using a

Magellan ProMark 3 DGPS with
<1m accuracy
. In addition,
the overall track was also logged with a Garmin
Oregon

550
GPS. A Magellan Mobile Mapper CX was also carried as a back
-
up logger.

At each distinct habitat, the substrat
a

and dominant/characteristic species were identifie
d
according to MNCR methodology
, together with site position (centre and/or extent depending
on size) using
the D
GPS with data loggers. The major species/taxonomic groups at each
site were additionally re
corded and where possible, subtle differences in species
composition noted.

Within important biotopes, a more detailed quantitative species list was obtained by taking
samples within the distinct biotopes for detailed analysis as required back
in

the lab
oratory.

Additional target notes and more detailed information were recorded if the site biotope could
not be immediately determined, including representative samples.
S
amples were taken
following the standard methodologies described by Dalkin and Barne
tt (2001), along with
sediment samples for subsequent Particle Size Analysis (PSA). Species of indeterminate
Biological survey of intertidal sediments of the Inner Solway Firth,
Spring 2011

Report to Natural England

Page
12

Institute of Estuarine and Coastal Studies

identity from the
in situ

biotope recording were retained for laboratory identification.

The
position of all samples was logged using DGPS.

D
igit
al photographs of both the area and the characteristic
substratum

were taken, and these
were cross referenced with the survey notes and maps.
One set of photographs were taken
using a ruggedised waterproof camera with locations cross referenced to sample
points. In
addition, a second set of photographs
was collected at each point
using the Garmin Oregon
550 with automatic position and direction tagging.

All data recorded w
ere

re
-
examined on a daily basis in order to produce fair maps for each
site as a pr
ecaution against incomplete data or data loss
,

and to prevent misinterpretation.
All digital data were transferred from
the survey
devices (GPSs and cameras) at the end of
each day and copied both to laptop and USB memory stick.
On completion of each day
's
survey, the data and biotopes assigned on the fair maps were assess
ed and copied onto a
master map
.

On return to the IECS laboratory, samples for invertebrate analysis were processed for
taxonomic analysis, and species identified and enumerated for each

sample location. In
addition, sediment samples were analysed for particle distribution and organic content (LOI).
The taxonomic data (raw and standardised

to 1m
2
)
, together with the PSA and LOI
information are
Appended to this document
.

Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural England

Page
13

Institute of Estuarine and Coastal Studies


Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural England

Page
14

Institute of Estuarine and Coastal Studies


Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural England

Page
15

Institute of Estuarine and Coastal Studies


Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural
England

Page
16

Institute of Estuarine and Coastal Studies

3.
RESULTS

The following section
describes the results of the 2011 survey programme.
The results are
described on a site by site basis

(three sites)
, using discrete areas and natural breaks in
habitat as appropriate divisions.


3
.1

Old Graitney (North Bank) to
Port Carlisle

(South Bank
)

3
.1
.1

O
VERVIEW

This extreme upper estuarine area includes two freshwater input channels into the Solway

Firth
, i.e. the River Esk to the north of Rockcliffe Marsh, and the River Eden to the south of
the marsh. The two main
fluvial
channels
dominate the morphology of the upper estuary
although they
are relatively narrow

and shelve steeply. In fact this channel morphology,
together with the wider Solway plan
-
form means that the main fluvial channels of the inner
firth
are

subject to small bor
es on
even moderate
spring tides.

Between these two channel
s,

in the extreme upper part of the system
,

is an area of high
marsh. This includes extensive high saltmarsh, as well as grazing marsh (
Rockcliffe Marsh
).
Fronting the marsh is an extensive are
a of intertidal soft sediment, including areas of high
sand bank, some of which appear to remain uncovered by the tide even around high water
during neap phases, and extensive low sand flats which are present in both the Eden (e.g.
around Burghmarsh Point)

and Esk (e.g. around Redkirk Point) branches (adjacent to the
freshwater channels, and around the confluence of these channels (e.g. upstream from
around Torduff Point to Port Carlisle)

During the 2011 survey
,

three main intertidal soft sediment habitats
were identified within the
area (in addition to high saltmarsh):



Large elevated fine to medium fine sand flats;



Extensive flat low shore firm rippled muddy sand to fine sand flats;



Relatively narrow sandy mud with occasional cobble on the fringing banks.

N
otably during the
2011 survey
, a
small
tidal bore was
propagated,

in particular on the Eden
c
hannel
from
c.
Port Carlisle (limit of observation downstream), and presumably running up
past Burghmarsh Point
.

This occurred on a tide which was
c.
3 days prior

to the spring tide,
on a set of moderate spring tides, with a high water of 3.6m predicted for Redkirk on the day
of survey against mean high water spring tide of 3.8m and a highest astronomical tide of
5.1m. It is considered that the habitats in this se
ction of the estuary will therefore be
influenced by both a combination of high residence time, low but variable salinity and high
current velocities.

Examples of the three main habitats identified in this area are given in plates 1, 2 and 3 over.
It shou
ld however be noted that transition habitats were also observed between these
habitats. Habitat details are described in Section 1.1.2.

Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural
England

Page
17

Institute of Estuarine and Coastal Studies


Plate 1: Upper estuary elevated sand flats.

This habitat was recorded in the upper estuary to the
south of the
channel of the River Esk, and was primarily
adjacent to the main marsh area.

The habitat consisted of a fine to medium fine sand, and
was relatively firm. Some ripple features were present,
but not consistently and it appeared that the habitat, due
to its

elevation might not be covered on neap tides. Little
or no fauna were observed on the surface, nor any casts,
although some shell debris was present. Perhaps of
greatest note was the use of the habitat by geese and
gulls as a roost, with substantial ass
ociated faecal matter
observed in some areas. This habitat gradually
developed from the low shore feature described in
P
late 2.


Plate 2: Upper estuary extensive low shore sand flats.

This habitat was recorded in the upper estuary on either
sides of
the freshwater channels of the Rivers Esk and
Eden, as well as more extensively, around their
confluence. This was the dominant habitat within the
survey area.

The habitat consisted of a firm rippled fine sand with
variable standing water in the ripples.

Very few surficial
fauna were noted, with
Arenicola

casts occasionally
present as well as occasional amphipod crustaceans.


Plate 3: Upper estuary narrow fringing sandy mud.

The south shore of the River Eden channel, in the inner
estuary featured a gre
ater slope, and graded from a
habitat similar to that above, into a sandy mud and
occasional cobble sediment up shore towards the green
-
shore erosion step.

The habitat consisted of a moderately soft, but sandy
mud, with some cobble content (in places cob
bles overlain
by the sandy mud) and no rippling.
Hydrobia

were
observed as abundant on the surface, together with the
presence of
Corophium
.

Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural
England

Page
18

Institute of Estuarine and Coastal Studies

3
.1.2

H
ABITAT
D
ESCRIPTION

Around the launch point at Stormont on the north bank of the River Esk, the relatively

narrow
fringing habitat consisted of patches cobble with some ephemeral algae (
Enteromorpha

sp.)
and decaying strandline vegetative matter,
LR.FLR.Eph.EphX
.

The opposite (south bank) of the Esk channel featured a shelving fine sand flat which
increased in

elevation to a mid height mid channel bank. This featured a firm fine rippled
sand with some
Macoma

debris but no visible fauna or casts. Standing water was variable
within the feature, becoming wetter with elevation and distance from channel. The habi
tat is
considered to be
LSa.MuSa.MacAre
, despite the absence of any visible
Arenicola

casts

(Plate
RK
1)
.



Plate
RK
1

LSa.MuSa.MacAre

The elevation of the soft sediment feature continued to increase towards the south shore of
the River Esk ‘arm’. This area featured a fine sand but with patches of medium fine sand
within it, with no apparent change to fauna. The feature was drier than t
he mid channel bank
habitat and was slightly but patchily rippled and remained firm. No fauna were visible, but
the area was notable for an extensive goose and gull roost and associated with this roost
was a considerable quantity of faecal material. The
feature is considered to support the
predominantly barren sand biotope
LSa.MoSa.BarSa

(Plate
RK
2)
.



Plate
RK
2

LSa.MoSa.BarSa

Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural
England

Page
19

Institute of Estuarine and Coastal Studies

Continuing from this habitat the elevated bank immediately adjacent to the Rockliffe Marsh
saltmarsh again supported no visi
ble fauna but was used as a goose and gull roost with
substantial faecal matter present. Sediment in this area was finely laminated with darker
bands at depth, and although firm, was not rippled and had a more muddy component
(muddy sand).
Macoma

shell d
ebris was present with some
Corophium

burrows and
occasional
Macoma

and polychaete burrows recorded in the sediment. This habitat was
considered to be the biotope
LSa.MuSa.BatCare

(Plate
RK
3)
.



Plate
RK
3

LSa.MuSa.BatCare

Running west from Rockcliffe Marsh into the main confluence area was a further elevated
sand bank habitat. This was again a very well drained muddy fine sand sediment with no
ripple structures present and no visible surficial infauna, but which was used a
s a goose and
gull roost. Approximately 2
-
3mm under the surface was a <1mm band with a green tinge
possibly indicating the presence of a microphytobenthos (e.g. Euglenophyta). Within the
sediment were
Corophium

in variable density from occasional to comm
on, as well as
occasional small
Macoma

and spionid tubes, the habitat considered to be a transition
between
LSa.MuSa.BatCare

and LSa.MuSa.HedMac

(Plate
RK
4).



Plate
RK
4

LSa.MuSa.BatCare

to LSa.MuSa.HedMac

West
and north of the apex
of Rockcliffe Marsh and between the confluence of the Rivers
Esk and Eden, an extensive low sand flat habitat was recorded, rapidly transitioning from the
elevated upper shore bank running along the northern edge of Rockcliffe Marsh. This low
Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural
England

Page
20

Institute of Estuarine and Coastal Studies

shore tidal
flat comprised a very firm rippled fine sand with
patchy surficial mud and
variable
standing water associated with the ripple features.
No

fauna were visible on the surface,
and the presence of
Arenicola

casts, although occasionally observed was scarce (<
1 cast
per 10m
2
). However, examination of the sediment indicated abundant amphipod
crustaceans (
Bathyporeia

sp, as well as polychaete tubes (Spionid sp.), patchy
Corophium

and occasional
Macoma
. This extensive habitat appears to have aspects of both the
LSa.MuSa.MacAre

and
LSa.MuSa.BatCare

biotopes, and is significantly influenced by the
high current velocities of the area


and is particularly prevalent towards the River Esk
channel
.


In the north of the area it was considered to be closer to
LSa.MuSa.MacAre

(Plate
RK
5), with a more muddy or very fine sand surface).



Plate
RK
5

LSa.MuSa.MacAre /
LSa.MuSa.BatCare

Towards the centre of the low sand flat formed by the two tributaries, the habitat tended to
have a lower mud content on the surface, and consist of a well drained fine firm rippled sand
with
no

fauna visible on the surface (very occasional
Arenicola
), but

with
Bathyporeia

and
Corophium

still
patchily present.


This was considered to be closer to the
LSa.MuSa.BatCare

biotope although still within the
LSa.MuSa.MacAre

and
LSa.MuSa.BatCare

complex (Plate
RK
6)
.



Plate
RK
6

LSa.MuSa.MacAre /
LSa.MuSa.BatCare

Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural
England

Page
21

Institute of Estuarine and Coastal Studies

The extensive low mudflat described above is constrained downstream by the River Eden
channel, which has a small area of firm fine sand along its northe
rn edge in this area. No
fauna

were visible, and the high energy mobile sand environment suggests an i
mpoverished
fauna. This is considered to be an impoverished version of
LSa.MuSa.BatCare

(Plate
RK
7
)
.



Plate
RK
7

Impoverished

LSa.MuSa.BatCare

This habitat was also present on the south bank edge of the Eden channel, but then graded
into a more muddy sand on the mid shore with abundant
Hydrobia

and common
Corophium

(
LSa.MuSa.BatCare
).
On the upper shore, this transitioned to a sandy mud, with oc
casional
bare cobbles, with
Corophium

still common but patchy, and
Hydrobia

on the surface
(
LSa.MuSa.MacAre

LSa.MuSa.BatCare

mosaic)

(Plate
RK
8).



Plate
RK
8

LSa.MuSa.MacAre

/
LSa.MuSa.BatCare

Table 3
summarises the individual track files, associated
habitat description, biotopes and
photograph references.




Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural
England

Page
22

Institute of Estuarine and Coastal Studies


Table 3:
Redkirk to Burgh Marsh

Biotope Summary per Track

Track/Point

Description

Biotope

Photo Ref.

Track 0

Launch area

Mosaic of pebble, cobble, and small boulders with overlying
muddy silt of variable depth (up to 5 cm in some areas).
Enteromorpha

sp. (F) covering hard substrata.

LR.FLR.Eph.EphX

No Photo

Track 1

South of the channel. Slope of mid
-
shore bank with firm
slightly ripple fine sand. No visible fauna but some shell
debris (
Macoma
). Some Macoma & Arenicola present but in
very low numbers.

LSa.MuSa.MacAre

Plate
RK
1

Track 2

Top of mid
-
shore bank with higher water content on very fine
firm slightly rippled san
d. No visible surficial fauna, but
Macoma

in samples.

LSa.MuSa.MacAre

As Plate
RK
1

Track 3

Elevation increases to high bank adjacent to marsh. Fine to
medium fine sand with no visible fauna. Extensive gull &
goose roost

LSa.MoSa.BarSa

Plate
RK
2

Track
4

Slightly rippled, mobile, muddy sand on elevated bank in
lower energy area.
Corophium

present with
Macoma
.

LSa.MuSa.BatCare


Plate
RK
3

Track 5

Firm, damp, rippled, muddy fine sand with no visible anoxic
layer but with a sub
-
surface narrow green band.
Some
Corophium

present in variable density as well as Macoma
and Spionids.

LSa.MuSa.BatCare
LSa.MuSa.HedMac

Plate
RK
4

Track 6

Extensive low elevation firm rippled fine sand flat between
the confluence of the two rivers and apparently a high
energy environment. Very occasional
Arenicola

casts,
Macoma
, patchy
Corophium

and abundant amphipods
(
Bathyporeia
).

LSa.MuSa.BatCare
LSa.MuS
a.MacAre

Plate
RK
6

Track 7

Narrow band of fine firm sand on the north side of the Eden
channel.

Impoverished due to high energy.

LSa.MuSa.BatCare

Plate
RK
7

T8
-
T10

No tracks


N/A

Track 11

Similar to Track 7, grading into a more muddy sand upshore.

LSa.MuSa.MacAre


Track 12

Mid to upper shore close to saltmarsh erosion step. Muddy
sand with slight rippling with abundant
Hydrobia

on the
surface and
Corophium
. In the upper shore occurrence of
patches of barren cobble.

LSa.MuSa.BatCare

LSa.MuSa.MacAre

Plate
RK
8

T13
-
T22

No tracks


N/A

Track 23

Low shore extensive fine firm rippled sand (part of the
feature described in T6 but further to the north). Variable
standing water with very occasional
Arenicola

cast (<1/m
2
).
Occasional
Macoma

and
Bathyporeia
.

LSa.MuSa.MacAre

LSa.MuSa.BatCare

Plate
RK
5

A map showing the location of the biotopes as discussed above is given in Map 4, over leaf.


Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural England

Page
23

Institute of Estuarine and Coastal Studies


Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural England

Page
24

Institute of Estuarine and Coastal Studies

3
.2
Cardurnock Flat
ts

and

Grune Cast

3
.2.1

O
VERVIEW

Cardurnock Flatts is an extensive area of intertidal sandflat in the Inner Solway, to the south
of the main Eden Channel

(and bounded by the channel in its northern and eastern extent)
.
For the most part, the habitat is backed by tidal grazing merse, and incised by a series of
drainage creeks. The southern area of the site features several cobble scars, these being
situated around the mouth of Moricambe Bay
, a large coastal inlet. To

the south of this inlet
lies the coastal feature Grune Point, with an intertidal area extending out to its west (Grune
Cast). At this point, the Eden Channel has developed into the Swatchway, through which
the majority of the inner estuary freshwater inp
ut drains, and which forms a substantial
channel. Offshore from this location by
c.
1km is Middle Bank, which forms an extensive
mobile mid channel sand bank.


Plate 4: Mid to upper shore extensive sand flats.

This habitat was extensively recorded in th
e intertidal
zone, running from the near shore down to near low water
off the Cardurnock peninsula. For its majority the habitat
was somewhat elevated, compared to the adjacent low
lying ‘delta’ area. The habitat consisted of a fine to
medium fine sand,
and was relatively firm. Some ripple
features were present, but not consistently. Similarly, the
habitat featured variable standing water cover, from an
absence, to, in one area, 100% cover to a depth of
c.
5mm. Surficial fauna were absent, but a variab
le density
of
Arenicola

casts were noted, ranging from <1/m
2

to
c.
50/m
2
.
Corophium

were also present, but with a patchy
distribution, with occasional
Macoma

and
Cerastoderma

often recorded, and
Macoma

and
Cerastoderma

shell
debris present. A similar hab
itat was observed on Grune
Cast.


Plate 5: Low elevation ‘delta’ sand flats.

This habitat was recorded across much of the ‘delta’ of
Moricambe Bay (with some, more elevated banks,
exhibiting features as described above for Plate 4). It
consisted of a fine sand with variable but quite substantial
at times, ripple features. Standin
g water was also
variable, but usually present within the ripple features,
and the area was crossed by a series of braided
channels.

Few surficial faunal features were observed (nor any
fauna), presumably due to the high energy and sediment
mobility in t
he area.

Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural England

Page
25

Institute of Estuarine and Coastal Studies

During the 2011 survey two main intertidal soft sediment habitats were identified within the
area (in addition to high saltmarsh):



Extensive flat low to middle shore firm rippled muddy sand to fine sand flats;



Low shore soft sediment ‘delta’
formed by the discharge from Moricambe Bay.

In addition, cobble/boulder habitats were present both in the form of intertidal scar areas and
in the upper
-
shore along the southern section of Grune Point. These habitats featured a
variable associated fauna,
from absence to a relatively abundant barnacle and littorinid
community.

3
.2.2

H
ABITAT
D
ESCRIPTION

As with the majority of the Cardurnock Flatts site, the upper shore
features a
grassland/grazed marsh merse
, with a small erosion step onto the intertidal s
andflats.
The
majority of the northern part of the survey area (off Cardurnock) consisted of a firm fine sand
with variable ripple and standing water features.
Arenicola

was present throughout most of
the area, although in
variable densities

and casts we
re absent from some of the upper shore
areas
. This general habitat was very extensive, within the wider area surveyed, stretching
from the near upper shore to near lower shore (the extreme upper and lower shore areas
were not surveyed). Along the upper s
hore
(transect running
c.
200 to 250m from the
merse
-
edge) the sediment was a fine firm sand with variable ripples and standing water.

Off Cardurnock village, the sediment was a very fine sand with only slight mud content.
Arenicola

cast density and rip
ple features were low to absent, but standing water was
substantial, with a
c.
5mm extensive overlying sheet recorded. However
Corophium

were
generally present, and often abundant, together with small polychaetes and amphipod
crustaceans. The habitat is
considered to be LSa.MuSa.BatCare

(Plate
CD
1)
.



Plate
CD
1

LSa.MuSa.BatCare

(standing water)

To the north
-
west of Cardurnock the standing water content reduced to an absence,
although the sediment type remained comparable with no casts or ripples present, but with
abundant
Corophium

again recorded (LSa.MuSa.BatCare)

(Plate
CD
2)
.

Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural England

Page
26

Institute of Estuarine and Coastal Studies



Plate
CD
2

LSa.MuSa.BatCare

North of this
c.
250m habitat band standing water increased with no sediment features and
abundant
Corophium

again characterising the area (LSa.MuSa.BatCare). This band
extended for
c.
1km northwards (with the transect moving to
c.
500m
from the shore) before
transitioning back into a drier area with a similar infauna (LSa.MuSa.BatCare) for
c.
250m,
prior to a further similar but drier 500m band of the same habitat. This marked the northern
extent of the survey on Cardurnock Flatts, the
transect ending
c.
500m from the merse
shoreline, but with the same habitat appearing to extend at least a further 500m to the north
in the mid to upper shore.

The mid to lower shore of the extensive Cardurnock Flatts sand flat was characterised by a
fin
e firm sand with variable ripple features, and importantly, by the presence of
Arenicola

casts in variable density from 10
-
50/m
2
. In the mid shore
Corophium

were also present,
although at a lower abundance than on the upper shore, with this reducing further in the
lower shore to an absence. As such, it is considered that there is a gradual transition within
the mid shore of this area from an upper shore LSa.
MuSa.BatCare to a
LSa.MuSa.MacAre

biotope, with the majority of the lower mid to low shore being
LSa.MuSa.MacAre

(Plate
CD
3)
.



Plate
CD
3

LSa.MuSa.
M
a
cAre

Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural England

Page
27

Institute of Estuarine and Coastal Studies

Towards the extreme low shore, west of Cardurnock village a scar ground was identified,
this pre
sumably having been exposed as a feature for a number of years as it featured a
navigation marker (in derelict condition), but is not marked on OS maps. This scar ground
consisted primarily of cobbles (with some pebbles and boulders) with considerable int
erstitial
fine muddy sand, and extended to the channel edge in the low shore. The majority of the
hard substratum was barren (with no encrusting fauna), although some of the larger cobbles
and boulders had some
Enteromorpha

cover and occasional
Mytilus ed
ulis

were present.
The under
-
boulder community was also relatively impoverished with occasional
Carcinus
maenas
and
Hediste diversicolor
. The soft sediment areas supported occasional
Arenicola

and
Macoma
, but in very low numbers. It is likely that the s
car is a mosaic of
LCS.Sh.BarSh
,
impoverished
LR.FLR.Eph.EphX

and interstitial impoverished
LSa.MuSa.MacAre

(Plate
CD
4).



Plate
CD4

LCS.Sh.BarSh, LR.FLR.Eph.EphX
&

LSa.MuSa.MacAre

scar
mosaic

South of the Cardurnock Flatts, is the entrance to the
coastal inlet Moricambe Bay. This
entrance was found to be characterised by a series of braided channels, with deltaic features
and the occasional more elevated mid channel bank. In general, the area was at a lower
elevation to that of the Cardurnock Flat
ts to the north. The sediment of the area was a firm
fine sand with variable rippling and substantial water, either standing or draining within the
shallow delta. The majority of the area surveyed had no surficial fauna and appeared to be
relatively mobi
le with a series of braided channels present (
LS.LSa.MoSa.BarSa
) (Plate
CD5).

Biological survey of intertidal sediments of the Inner Solway Firth, Spring 2011

Report to Natural England

Page
28

Institute of Estuarine and Coastal Studies



Plate
CD5

LS.LSa.MoSa.BarSa

However, o
n the northern edge

of this
, an area of medium fine
patchily
rippled sand
supported
Arenicola

at
up to
10/m
2

as well as occasional live
Cerastoderma

and
Macoma

(and shell debris) and occasional
Corophium

as well as
Bathyporeia

and
Gammarus
.
Abundance levels were generally low and it is suggested that the habitat is a transition
between
LS.LSa.MuSa.CerPo
,
LSa.Mu
Sa.MacAre

and LSa.MuSa.BatCare

(Plate CD6)
,
possibly reflecting the mobility and energy conditions at the edge of the Moricambe Bay
delta area.



Plate
CD6

LS.LSa.MuSa.CerPo, LSa.MuSa.MacAre
and LSa.MuSa.BatCare transition

The mid channel elevated banks of the delta supported
Arenicola

casts of 10
-
25/m
2

(
LSa.MuSa.MacAre
).

South of the channel delta area, the area is dominated by the Grune Point landform and
Grune Cast (the intertidal zone to the west of the point was surveye
d on this occasion.
The
low to mid

shore of Grune Cast
around the north
-
western tip of the point
comprised a fine
sand
with occasional
Arenicola

casts (<1/10m
2
). This was consistent with habitats from the
delta and mid channel banks (
LS.LSa.MoSa.BarSa
)

d
eveloping into
LSa.MuSa.MacAre

with
increased stability)

Plate CD7)
.