Transcript Slide 1

Matthew Service
• Anthropogenic Pressures
Principal Pressures
• Physical disturbance from direct impacts
Stresses
on
the
environment
and resulting from morphological changes
in form of direct pressures
• Contaminants;
Heavy metals and Organic
such a emmissions, riverine
• Nutrients
& direct inputs
Catchment
Catchment
Area
(km2)
Strangford
771.5
Length
Maximum
Surface
Max.
Volume Coastline
Urban- Surface
Rough
Other
Area Industrial Arable Grass
Forest
land
Width
Area LW Area HW grazing
Depth
km2 Industrial
% of area
(km)
(km)
(km2)
(km2)
(m)
(106 m3)
(km)
588
5.2
8.0
84.2
0.1
1.8
0.7
30.0
8.0
106.2
182.8
66.0
1 251.5
240.0
1. Introduction
Residual near surface circulation
Potential energy anomaly (J m3)
and drifter tracks
• 1857 Dickie reports presence of M
modiolus in Lough:
Time line
• oysters in “central area”
• cf 1900 Oyster fishery declines:
• cf 1930 Spartina introduced;
• Boyd (1969) describes plankton and
water quality;
• Jenkinson(1974) Describes
hydrodynamics
• 1970 first reports of Queen Scallop
trawling:
• Erwin 1977 Describes S Lough Benthos
• Roberts 1975 Describes M modiolus/Chlamys
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•
•
•
•
varia community;
1978 Spartina spraying started;
1979 Parker report on shellfish contaminants
forerunner of Musselwatch study;
1984 Investigation in double shelling and
links with TBT;
1984 Spartina spraying implicated as cause
of sediment release;
Late 1980’s Queen Scallop trawling expands;
• 1985 Ardmillan Bay designated under EC Shellfish
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•
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•
Waters Directive;
1989 Brown publishes report claiming trawling is
destroying M modiolus communities;
1990 DOE(NI) Commission Mathematical Model
1990 ISD report confirms trawling having impact;
1993 DANI(DARD) introduces fishing restrictions;
1993 DARD report on sediment metals
1995 Possible introduction of Sargassum
1996 Magorrian Thesis on Effects of commercial
trawling (DARD studentship);
• 1997 Spartina spraying resumed;
• 1997 DARD project on Recovery of benthic
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•
•
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communities project initiated
DARD/EHS report on Trophic Status of Lough
1998-2000 Further DARD Report on
Sediment Contaminants
1999 Sea defence reconstruction begun at
Newtownards;
2001 Release of sediment from Killyleagh
foreshore;
• Eutrophication
• Trace Contaminants (Heavy metals and
organics) in sediments;
• Shellfish contaminants;
• Physical disturbance;
• Algal toxins:
Routine Monitoring
• EC Shellfish Waters Directive
• EC Shellfish Hygiene Directive
• National Marine Monitoring Plan (OSPAR
JAMP)
• EHS Estuarine Classification
Water Quality:
• DARD/QUB AESD conducted a spatial and
temporal survey of nutrient loading to the lough
and nutrients, phytoplankton and chlorophyll in
the lough over the period 1993-1996.
• EHS estuarine class programme collects limited
low frequency nutrient and plankton data.EHS
also monitor heavy metals in water as part of the
EC Shellfish Waters monitoring .
• DARD- AESD analyse samples from active
shellfish sites for presence of toxic algae
fortnightly. This is reported annually.
• EHS-EP report input data from Ballyrickard STW,
Killyleagh STW and Downpatrick STW.- the
OSPARCOM Loading Data
Loads(KG)
2500
2000
1500
Loads(KG)
1000
500
0
ZINC TOTAL
PCB 28
PCB 153
PCB 118
MERCURY
GAMMA-
CADMIUM
Nutrient Drivers:
• EC UWWT Directive
• EC Nitrates Directive
• Eutrophication is defined by the EC (in
the Urban Waste Water Treatment
Directive) as:
• the enrichment of waters by nutrients,
especially compounds of nitrogen
and/orphosphorus, causing an
accelerated growth of algae and higher
forms of plant life to produce an
undesirable disturbance to the balance
of organisms present in the water and to
the quality of the water concerned
• Taylor and Service (1998)concluded
• Irish Sea is the largest source of nitrogen, phosphate
•
and silicate loading to Strangford Lough
The total annual anthropogenic load of DIN and SRP
(excluding the Irish Sea and airborne deposition) to
the Lough are 1 201 and 116 tonnes, respectively;
• Eutrophication is defined by the EC (in
the Urban Waste Water Treatment
Directive) as:
• the enrichment of waters by nutrients,
especially compounds of nitrogen
and/orphosphorus, causing an
accelerated growth of algae and higher
forms of plant life to produce an
undesirable disturbance to the balance
of organisms present in the water and to
the quality of the water concerned
b.a.
Figure 41 : Sources of Summer
(August)DIN
DINLoads
Loads
Winter (January)
Direct Runoff
9%
Direct Runoff
34%
Rivers
30%
Rivers
60%
Estuarine
STWs Estuarine
6%
STWs
61%
Total Monthly Load = 27.60Tonnes
Total Monthly Load = 218.00Tonnes
54.55
54.50
Latitude N
54.45
54.40
54.35
54.30
54.25
-5.70
-5.65
-5.60
-5.55
Longitude W
-5.50
-5.45
Heavy Metals
• Killyleagh outfall generated more than 10 tonnes of chromium per
annum, although during the early 1990s, declined to nearer 1 tonne
per annum;
• The high mercury concentration in mussels from Whiterock were
similar to those found in mussels from the Inner Forth estuary in
Scotland (Davies and Pirie 1980 in Gault et al. 1983) ;
• TBT Implicated in double shelling in oysters;
TBT
• Routine monitoring for Imposex and
Intersex in Dogwhelks and Winkles by
EHS has shown little sign on effect;
• Edwards (2002) Suggested that Imposex
records in Whelks show a reduction in TBT
levels.
Sediment
Quality
• In 1990 approximately
30 samples were analysed
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at the <63um particle size level using an aqua
regia digest
In 1996 a smaller numbers of stations were
sampled and analysed for heavy metals at the
<2mm particle size level using an HF digest for
geochemical normalisation.
Hydrocarbons (PAH’s) a spatial survey was
carried out in 2000 at again about 12 sites.
DARD have one NMMP sediment station in the
Lough that is sampled for heavy metals,
pesticides, PAH’s.
• EHS –EP have sediment sampling sites(4?) in the
lough as part of their Estuarine Classification
54.6
Newtownards
54.55
SL3
Comber
SL1
SL4
SL5
54.5
SL2
SL6
SL7
SL8
SL9
54.45
SL11
SL10
SL13
54.4
SL12
SL14
SL15
54.35
Quoile
54.3
54.25
54.2
5.7
5.65
5.6
5.55
5.5
5.45
• Service (1993) concluded that with the exception of
chromium and mercury, all other metals show strong
co-correlation and are therefore from a common,
geochemical weathering source. By contrast,
chromium and mercury are most likely to originate
from the point source outfall at Killyleagh.
2. Trace metal contamination
250
NWIS
Belfast
Strangford
-1
Zn (µg g )
200
150
100
50
0
0
2
4
Al (%)
•
6
8
Sediment Metals 2000
180
160
Irish Sea Sites
AL
140
Cu
120
PB
100
NI
80
B
Zn
60
AS
40
CR
20
0
NMP4
nmp5
38a
NMp3
s lough
300
Killyleagh
Kirrcubbin
Paddys
K illy Point
le a g h
Newtownards
K irrc u b b in
Quoile
Mean
P a d d y s P o in t
4 0 0 .0
250
3 5 0 .0
3 0 0 .0
200
N e w to w n a rd s
2 5 0 .0
Q u o ile
150
M ean
2 0 0 .0
1 5 0 .0
100
1 0 0 .0
50
5 0 .0
0
88
999
1 19
1 199
9966
1 1999
9 22
1 199
9944
1
1 9 988
88
1
1 9 99
9 00
9
1 9 84
8
19 4
1 9 86
86
19
8
19 0
198 0
8
19 2
8
1 2
0 .0
Heavy Metals in Modiolus modiolus
35.00
30.00
*10
25.00
20.00
Donaghadee
*10
15.00
S Lough
10.00
5.00
0.00
Ag
Cd
Cr
Cu
Fe
Hg
Ni
Pb
Zn
As
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Physical disturbance due to:
Trawling or dredging;
Sediment relocation:
Release of sediment or changes in
coastal cell
• change in prevailing wind
Otter Boards or trawls hold
the net open and may impact
the sea bed
Tickler chains banned in
Strangford Lough
Sediment plumes
may help “herd”
fish
• The worst damage caused by otter boards
• The area between scars showed no
textural differences
• area effects has a characteristic texture
2002
28% L.Depurator
7% C.Papposus
9% M.Rugosa
27% A.rubens
0.5% C.Maenas
1.5% B.Undatum
28%
E.Esculentus
Side-scan sonar survey area
• Strangford is subject to variety of
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•
•
pressures
arising both from the catchment
and directly
there is no evidence that the Lough
is eutrophic or heavily
contaminated
trawling can impact seabed
communities