Electronic Supplementary Material: S.D. Ling et al. Global regime shift dynamics of catastrophic sea urchin overgrazing
Table S1. Summary of correlative data between percent ‘landscape’ cover (%) of macroalgal canopy formers and sea urchin biomass (grams. m-2) for 13
regions worldwide. Where required, conversion of macroalgal abundance to % Cover was based only on large canopy-forming adults where data sets split
abundance or biomass estimates by life-history stages. For sea urchins, biomass (grams wet weight) was calculated using allometric conversion of TD (Test
Diameter in mm) to biomass where individual sea urchin test diameters were recorded; else an average individual biomass of sea urchins was estimated for
particular regions.
Macroalgal canopy cover
# Hemisphere Region
1 Southern
Australia -Tas/NSW
2 Southern
Australia – Tas/Vic
3 Southern
New Zealand
4 Southern
Chile
Sites
Spatial
extent
(km)
n
164
37
16
5
4
1,500
500
2,000
400
5,264
628
642
511
Year sampled
2001-2008
2001-2013
1999-2003
2012
Dominant genera
Ecklonia
Ecklonia
Ecklonia
Lessonia
Quadrat
scale (m)
5x1
5x1
1x1
1x1
[Individual holdfast
diameter measured in situ]
5
6
7
8
9
10
11
12
13
Southern
Northern
Northern
Northern
Northern
Northern
Northern
Northern
Northern
South Africa
Nova Scotia
Gulf of St. Lawrence
Norway
Canary Islands
California
British Columbia
Mediterranean
Japan
6
2
18
51
12
5
11
8
100
100
100
1,000
500
250
250
6
2
1
1
162
115
157
1,025
800
581
1988/89,2001/05-06
1992-1993
2011
2007-2012
2001-2004
2001-2012 (annually)
161 2012
278 1999
320 2013
Ecklonia/ Laminaria
Sacharrina/ Laminaria
Sacharrina/ Laminaria
Sacharrina/ Laminaria
Lobophora/ Cystoseira
Macrocysits
Laminaria
Pterygophora
Eisenia
1x1
1x1
0.5x0.5
0.5x0.5
0.5x0.5
20x2
Nereocystis/
Laminaria
1x1
Cystoseira
Eisenia/ Saccharina
/ Undaria
Sea urchin abundance
% Cover / conversion
Direct measure
Direct measure
% Cover=8.92ln(biomass) +2.29
Morphometric scaling:
Lessonia canopy area =
pi*(3.5*individ. holdfast radius)2
% Cover= 0.1432(biomass) + 5.518
Direct measure
Direct measure
Direct measure
Direct measure
%Cover to Stipe Count (SC):
Dominant genera
Centrostephanus
Heliocidaris
Evechinus
Tetrapygus
Quadrat
scale (m)
5x1
5x1
1x1
1x1
Biomass (B, grams)
B=0.0106(TD)2.2319
B=0.0014(TD)2.668
B=0.000843(TD)2.8288
B= 298g. individ.-1
Parechinus
Strongylocentrotus
Strongylocentrotus
Strongylocentrotus
Diadema
Strongylocentrotus
1x1
1x1
0.5x0.5
0.5x0.5
5x4
3x1
B= 27.5g.Individ.-1
Direct measure
B = 0.0007(TD)2.8539
B= 0.0007(TD)2.8539
B= 0.0008(TD)2.8941
B=0.0499(TD) + 0.0019
Strongylocentrotus
1x1
S.franciscanus:
B=0.0005*(TD)2.9572;
Macrocystis; %Cover=3.77*SC
Eisenia; %Cover=8.98*SC
Pterygophora; %Cover=2.23*SC
Laminaria; %Cover=0.89*SC
Morphometric scaling:
Genus
Nereocystis
Cymathere
Costeria
Alaria
Laminaria
Saccharina
Pterygophora
Eisenia
1x1
1x1
Direct measure
Direct measure
%Cover of 1m2/individ.
100
25
21
20
16
15
7
2
S. purpuratus
B=0.0005*(TD)2.9598
Paracentrotus
Strongylocentrotus
1x1
1x1
B=0.00319(TD)2.479
B= 79g.individ.-1
1
Electronic Supplementary Material: S.D. Ling et al. Global regime shift dynamics of catastrophic sea urchin overgrazing
Table S2. Summary of observational and manipulative experiments detailing the magnitude and directional
response of macroalgal habitat (both forward and reverse regime shifts) following change in sea urchin
abundance. Studies were included if stated magnitudes in the macroalgal response and sea urchin abundance
could be standardized as percentage cover (%) for macroalgae and biomass (grams. m-2) for sea urchins
respectively. Experiments involved sudden changes in urchin biomass density between “Start” & “End”:
experimenters either reduced or increased urchins to a target density; or in the case of observational studies,
either disease (reverse shifts) or local aggregation (forward shifts) also caused sudden change in urchin
density. But see exception (study #43) in footnote below.
#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
Hemisphere
Northern
Southern
Southern
Northern
Southern
Southern
Northern
Southern
Southern
Northern
Northern
Northern
Southern
Southern
Northern
Northern
Northern
Northern
Northern
Southern
Southern
Southern
Southern
Southern
Southern
Southern
Southern
Southern
Southern
Southern
Southern
Northern
Northern
Southern
Northern
Northern
Southern
Northern
Northern
Northern
Northern
Northern
Southern
Northern
Southern
Northern
Northern
Northern
Southern
Northern
Northern
Northern
Northern
Northern
Northern
Northern
Northern
Region
New England
Australia
Australia
British Columbia
Australia
Australia
California
Australia
Australia
Nova Scotia
Nova Scotia
Nova Scotia
Australia
Australia
Nova Scotia
Canary Islands
Canary Islands
Nova Scotia
Alaska
Australia
New Zealand
Australia
Australia
Australia
Australia
Australia
Australia
Australia
Australia
New Zealand
New Zealand
British Columbia
British Columbia
Australia
New England
Nova Scotia
Australia
Nova Scotia
British Columbia
Nova Scotia
California
Newfoundland
New Zealand
British Columbia
Australia
California
Nova Scotia
Nova Scotia
Australia
Norway
Canary Islands
Mediterranean
Mediterranean
Canary Islands
Mediterranean
Canary Islands
Canary Islands
Experiment
Observational
Manipulation
Manipulation
Observational
Manipulation
Manipulation
Observational
Manipulation
Manipulation
Manipulation
Observational
Observational
Manipulation
Manipulation
Observational
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Observational
Observational
Observational
Manipulation
Observational
Manipulation
Observational
Observational
Observational
Manipulation
Manipulation
Manipulation
Observational
Manipulation
Observational
Manipulation
Observational
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Manipulation
Regime
shift
direction
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Fwd
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Rev
Urchin
Urchin
biomass
biomass
Start (g.m-2) End (g.m-2)
0
12,228
0
7,767
932
6,136
5,770
5,770
0
3,107
0
2,535
1,246
1,246
1,162
1,162
0
1,014
0
883
691
691
667
667
581
581
0
507
233
233
27
210
9
150
804
0
3,506
0
464
0
2,261
0
1,057
0
559
0
401
0
757
0
456
0
2,535
0
1,521
0
1,014
0
912
0
912
0
2,900
0
4,579
0
2,317
0
4,673
0
1208
0
191
0
480
5
2,198
15
201
18
1,254
25
413
41
635
70
2,314
76
581
79
623
89
2,200
102
128
128
1,521
254
1,388
324
112
0
208
5
231
5
185
12
336
19
170
20
150
57
Urchin
density
end
(individ.
m-2)
280
90
80
322
40
10
7
4
4
34
120
93
2
2
32
7
8
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.5
0.1
15
0.1
3
0.5
0.3
0.5
0.5
13
24
1
6
0
0.2
0.2
0.5
1
1
2
% Cover
canopy
macroalgae
start
100
55
60
39
68
95
38
71
95
98
20
84
71
95
79
54
85
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.3
0
0
0
2
0
0
0
0
0
0
0
17
0
2
0
0
0
0
% Cover
canopy
macroalgae
end
0
7
0
1
37
20
8
12
70
0
0
0
23
70
0
12
0
59
100
100
12
93
78
37
92
91
48
30
28
28
42
100
100
88
100
100
52
100
100
25
22
9
50
100
25
100
26
90
30
95
46
41
54
54
70
85
54
% Cover
Duration
canopy
of
macroalgae response
loss/gain
(months)
100
3
48
7
60
4
38
11
30
7
75
5
30
3
58
6
25
5
98
3
20
24
83
1
47
6
25
5
78
3
42
6
85
9
59
4
100
12
100
6
12
10
93
18
77
18
37
18
92
18
91
18
48
18
30
18
28
5
27
18
42
18
100
72
100
12
88
20
100
25
100
36
52
13
100
33
100
12
25
21
22
8
9
10
48
300*
100
24
25
12
100
12
26
23
90
19
30
18
95
36
29
12
41
16
52
18
54
6
70
48
85
10
54
6
Source
Witman, 1985
Wright et al 2005
Wright et al 2005
Foreman 1977
Wright et al 2005
Hill et al 2003
Dean et al 1984
Strain & Johnson 2009
Hill et al 2003
Johnson & Mann 1990
Miller 1985
Scheilbling et al 1999
Strain & Johnson 2009
Hill et al 2003
Scheilbling et al 1999
Hernández et al. unpub. data
Hernández et al. unpub. data
Johnson & Mann 1990
Duggins 1980
Kriegisch et al. unpub. data
Shears & Babcock 2002
Ling 2008
Ling 2008
Ling 2008
Ling unpub. 2008-2011
Ling unpub. 2008-2011
Andrew & Underwood 1993
Andrew et al 1998
Hill et al 2003
Andrew & Choat 1982
Andrew & Choat 1982
Watson & Estes 2011
Watson & Estes 2011
Andrew 1991
Witman 1987
Scheibling, 1986
Strain & Johnson 2013
Miller & Colodey 1983
Watson & Estes 2011
Miller 1985
Cowen et al 1982
Keats et al 1990
Shears & Babcock 2003
Watson & Estes 2011
Ling et al 2010
Pearse & Hines 1979
Himmelman et al 1983
Schielbling et al 1999
Andrew et al 1998
Leinass & Christie 1996
Ortega-Borges et al 2009
Bendetti-cecchi et al 1998
Bulleri et al 1999
Hernández et al. unpub. data
Hereu 2004
Hernández et al. unpub. data
Hernández et al. unpub. data
*Note that for purposes of calculating an average time for macroalgae recovery once urchin abundance falls below the critical reverse-shift threshold, the long-term
recovery of macroalgae observed inside the Leigh Marine Reserve over 25 years (300 months) was excluded given the long lag times involved in the re-establishment
of functional urchin predators and ultimately reduction in urchin abundance (Shears & Babcock 2003).
2
Electronic Supplementary Material: S.D. Ling et al. Global regime shift dynamics of catastrophic sea urchin overgrazing
Fig. S1. Example images of alternative macroalgal bed and grazed sea urchin barren states of rocky reef
systems worldwide. Red arrows indicate the forward-shift caused by sea urchin overgrazing from macroalgal
dominated to urchin dominated barrens; blue arrows indicate the reverse-shift from urchin barrens back to
macroalgal habitat once grazing pressure is alleviated. Dominant macroalgal and barrens-forming sea urchin
species are listed respectively - photographic credits are given in square brackets: Northern Hemisphere
systems, a.) Nova Scotia (Saccharina latissima & Strogylocentrotus droebachiensis [by Scott Ling]), b.) British
Columbia (Nereocystis luetkeana & S. franciscanus [by Mark Wunsch], c.) California (Pterygophora californica
[by Alejandro Perez-Matus] & S. franciscanus plus S. purpuratus [by Scott Ling], d) Japan (Saccharina japonica
& S. nudus [by Daisuke Fujita]), e) Mediterranean (Cystoseira balearica & Paracentrotus lividus [by Bernat
Hereu]), f) Canary Islands (Lobophora variegata & Diadema africanum [by Scott Ling]); Southern Hemisphere
systems, g) Australia (Ecklonia radiata & Heliocidaris erythrogramma [by Scott Ling] - for images of Australian
urchin barrens formed by Centrostephanus rodgersii - see Ling & Johnson 2012; Ling 2013), h) New Zealand (E.
radiata & Evechinus chloriticus [by Nick Shears], i) Chile (Lessonia trabeculata & Tetrapygus niger [by
Alejandro Perez-Matus]), j) South Africa, Ecklonia maxima and Laminaria pallida [by Rob Tarr] & Parechinus
angulosus [by Rob Tarr]).
3
Electronic Supplementary Material: S.D. Ling et al. Global regime shift dynamics of catastrophic sea urchin overgrazing
Fig. S2. Map showing the 13 globally representative temperate rocky reef systems known to occur as algal bed
or urchin barrens states (temperate zones encapsulated by dotted lines within each hemisphere; equator is
shown as dash-dot line). Ordered west to east from Northern to Southern Hemispheres, the representative
reef systems covered 11 regions: 1. British Columbia (Gulf of Alaska, NE Pacific); 2. California (NE Pacific); 3.
Nova Scotia (NW Atlantic); 4. Gulf of St. Lawrence (NW Atlantic); 5. Canary Is. (NE Atlantic); 6. Norway
(Norwegian Sea, NE Atlantic); 7. Mediterranean (Mediterranean Sea, NE Atlantic); 8. Japan (NW Pacific); 9.
Chile (SE Pacific); 10. South Africa (W Indian); 11. Victoria (SE Australia, SW Pacific); 12. Tasmania (SE Australia,
SW Pacific); 13. New Zealand (SW Pacific Ocean). Refer to Fig. S1 for particular sea urchin and macroalgal
species occurring within each reef system.
4
Electronic Supplementary Material: S.D. Ling et al. Global regime shift dynamics of catastrophic sea urchin overgrazing
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