BACI-design – example:”The Blue
Reef Project” at Læsø Trindel,
Kattegat
Josianne G. Støttrup,
Claus Stenberg, Karsten Dahl
Before
After
Restaurering i marin miljø
3–4 februar 2015 - Sverige
DCE, Århus University
Danish Center for Environment and
Energy
BACI
B Before
A After
C Control
I Impact
Y
x
x
Impact
x
x
x
x
x
x
x
x
x
x
Before
x
x
x
Control
x
After
Time
Step change between Before and After Impact
2
DTU Aqua, Technical University of Denmark
Four standard BACI designs:
1
3
Single impact site – single control site
One year Before – one year after
2
Single/multiple impact site – multiple control sites
One year Before – one year after
3
Single impact site – single control site
Multiple years Before – multiple years after
4
Single impact site – multiple control sites
Multiple years Before – multiple years after
DTU Aqua, Technical University of Denmark
From Carl James Schwarz,
Simon Fraser Univ. Canada
BACI
BACI designs are good for:
• Large potential changes after impact
• Montoring for changes in the MEAN (not changes in
variability)
From: Carl James
Schwarz, Simon Fraser
Univ. Canada
BLUE REEF = only BA possible due to limited funding.
4
DTU Aqua, Technical University of Denmark
Baggrund for BLUE
REEF
Oversigtskort fra
én stenfisker
5
DTU Aqua, Technical University of Denmark
Hvad sker det når stenene fjernes helt eller
delvist fra stenrev
6
DTU Aqua, Technical University of Denmark
Project aims:
• To restore/improve the nature
quality status for Læsø Tindel
reef.
• Document the effect on
biological communities
– General flora and fauna
(AAU)
– Fish communities (DTU
Aqua)
Blue Reef: 2006-2013
7
DTU Aqua, Technical
of Dahl
Denmark
Photo:University
Karsten
Document
– Stop further erosion
8
DTU Aqua, Technical
of Dahl
Denmark
Photo:University
Karsten
Document
– Re-establish original depth of ~1.2 m
(now at ~4 m)
9
DTU Aqua, Technical
of Dahl
Denmark
Photo:University
Karsten
Document
– Restore perennial vegetation and bottom fauna
– Ensure good habitat for fish and shellfish
10
DTU Aqua, Technical
of Dahl
Denmark
Photo:University
Karsten
Nyt rev
• New stone areas at depth
intervals:
– 1½-4½m - 7 175 m2
– 4½-7½m - 11 725 m2
– 7½-10m - 8 500 m2
11
DTU Aqua, Technical University of Denmark
2008
2006
2012
2009(før)
2011
12
DTU Aqua, Technical University of Denmark
Hvad er samlet set den biologiske
gevinst?
• Hvad er tabt i askefri tørvægt? (den gamle bund)
– Fauna
220 kg
– Algal vegetation
1.280 kg
– Total
1.480 kg (< 3% infauna)
• Hvad er opnået – indtil videre?
– Fauna
3.075 kg
– Algevegetation
7.400 kg
– Total
10.475 kg
Estimeret overskud på cirka:
6100 kg askefri tørvægt alge biomasse
2850 kg fauna biomasse
13
DTU Aqua, Technical University of Denmark
Relativ forekomst af læbefisk, torskefisk
og andet i oversigtsgarn
Blue Reef projekt
14
DTU Aqua, Technical University of Denmark
Abundansen af torskefisk, læbefisk, fladfisk og
andet i oversigtsgarn, før og efter.
Blue Reef projekt
CPUE (est. catch in numbers station-1)
50
600
a. Gadidae
b. Labridae
Before
After
40
Before
After
500
30
400
20
300
10
200
0
100
0
West 6-10 m
Central 2-6 m
East 6-10 m
CPUE (est. catch in numbers station-1)
40
Central 2-6 m
East 6-10 m
25
c. Pleuronectiformes
d. Other
Before
After
Before
After
20
30
15
20
10
10
5
0
0
West 6-10 m
Central 2-6 m
Area
15
West 6-10 m
DTU Aqua, Technical University of Denmark
East 6-10 m
West 6-10 m
Central 2-6 m
East 6-10 m
Area
Støttrup et al. 2014
Lack of control
• CPUE from
research trawl
surveys within 50
km distance.
Cod data: no
increase in
abundance Before
(2005-2007) to After
(2010-2012).
16
DTU Aqua, Technical University of Denmark
Change in overall size distribution of fish
0.4
Before
Frequency
0.3
0.2
Fish>14 cm 16%
0.1
0.0
0.4
After
Frequency
0.3
0.2
Fish >14 cm 30%
0.1
0.0
0
10
20
30
40
Fish length (cm)
17
DTU Aqua, Technical University of Denmark
50
60
80000
P>0.55
< 20 cm
60000
On Blue Reef:
Cod < 20 cm; p<0.0001
40000
CPUE (number per ½ hour haul)
20000
0
250
20-30 cm
P<0.02
200
Cod 20-30 cm; p=0.0001
150
100
50
0
160
140
> 30 cm
P<0.001
120
100
80
60
40
20
0
Before
After
Period
CPUE from research trawl surveys
Before = 2005-2007
After
= 2010-2012
DTU Aqua, Technical University of Denmark
18
Cod >30 cm; p=0.0004
Regitrations of cod throughout the day/night
in July 2007
Sunrise
Sunset
8
Registrations %
6
4
2
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time of day
19
DTU Aqua, Technical University of Denmark
Gennemsnitlig antal timer pr mærket torsk
pr måned på Læsø Trindel for og efter
reetableringen.
Cod (G. morhua)
2.5
Before
After
llog10 (hours)
2.0
1.5
1.0
0.5
0.0
Jun
Jul
Aug Sep
Oct
Nov Dec
Month
20
DTU Aqua, Technical University of Denmark
Jan
Feb
Mar
Apr
May
Stomach content of cod > 20 cm
Cod >20 cm
Potential prey availability in environment
14000
Oct-2007
Oct-2012
0.6
-2
10000
0.4
8000
6000
4000
0.2
2000
0
0.0
er
th
O
ta
ae
da
po
ca
h
lyc
Po
s
lu
ol
M
Groups
tro
as
G
n
ea
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ru
n
ea
c
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ni
C
lc
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cr
a
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Bi
Sm
g
Bi
er
th
DTU Aqua, Technical University of Denmark
O
n
ea
ec
st
ru
c
ta
us
oa
yz
Br
lc
al
cr
sh
Fi
a
et
ha
lyc
Po
a
sc
lu
ol
M
da
po
tro
as
G
ria
da
ni
C
a
n
lvi
ea
va
Bi
Sm
g
Bi
Groups
21
2007
2012
12000
Numbers m
Relative occurrence in stomach (in numbers)
0.8
Blue Reef - Naturgenopretning af stenrev
tiltrækker marsvin
F
Mikkelsen et al. 2013.
Resultater
Læsø Trindel
Reference
18
16
PPM per day
14
12
10
8
6
4
2
0
2006
2007
2008
2009
2010
2011
2012
Year
PPM (Porpoise Positive Minute) = et minut med klik detektion
Mikkelsen et al. 2013.
Conclusions
• Reef stabilised and shallow part restored
• Significant increase in benthic macrophyte and bottom fauna
biomasses
• Fish fauna Before / After was dominated of species
belonging to the wrasse family (Labridae).
• Cod and saithe (Gadidae) were Before infrequent but
increased significantly After (factor 3-4).
• A full BACI may have given more conclusive results as to
whether the increase in cod was due to the restored reef.
24
DTU Aqua, Technical University of Denmark
Conclusions
• Size distribution patterns in fish changed and to include
larger individuals (relative occurrence of fish >14 cm
increased by a factor 2)
• Higher frequency of larger cod in restored reef area relative
to surrounding area
• Activity of cod on the reef showed a clear daily rhythm
(active on shallow parts during the night and passive in
deeper parts during the day). Activity on reef increased
After.
• Purpoises spent more time on Blue Reef After restoration
25
DTU Aqua, Technical University of Denmark
Acknowledgements
We would like to express our gratitude to all the participants in
the field programme and lab. work:
Local fishermen: Poul Olsen and Jørgen Rulle
DTU Aqua: Jesper Knudsen, Per Dolmer, Thomas Møller, Stine Kjærulf
Andersen, Per Ladewig, Hans-Jørn Aggerholm Christensen, Lars Thomsen,
Søren Post, Ole Henriksen, Marie Plambech, Nidia Graff
Aarhus University: Jan Damgaard Nielsen and Jens Larsen
Copenhagen University: Peter Rask Møller, Tammes Menne and Stine V.
Christensen