Supplemental Table S1. General linear model output for Hypothesis 1 (the three suspensionfeeders have disparate isotopic signatures owing to different particle capturing mechanisms).
F = F ratio; * denotes a significant effect.
δ13C
Model term
species
region
month
site
species*region
species*month
region*month
species*site
region*site
month*site
species*region*month
species*region*site
species*month*site
region*month*site
species*region*month*site
residuals
df
2
1
1
1
2
2
1
2
1
1
2
2
2
1
2
116
F
223.8
158.2
21.9
27.0
16.1
9.3
11.9
9.1
0.1
0.0
3.1
5.2
0.5
0.1
0.6
p
<0.001*
<0.001*
<0.001*
<0.001*
<0.001*
<0.001*
<0.001*
<0.001*
0.79
0.98
0.04*
0.01*
0.59
0.74
0.57
δ15N
F
828.9
9.8
4.0
2.0
0.1
0.3
6.7
6.1
12.8
0.2
0.3
4.9
0.6
0.0
2.3
p
<0.001*
<0.001*
<0.01*
0.16
0.94
0.74
0.01*
<0.01*
<0.001*
0.62
0.76
<0.01*
0.54
0.89
0.11
1
Supplemental Table S2. General linear model output for Hypotheses 2, 3 and 4 (2: isotopic signatures in the invertebrates vary between regions, as
the two regions studied are adjacent to estuaries with different annual freshwater output, 3: specimens collected down-current of each estuary mouth
have increased dietary inputs of terrestrially-derived matter compared with up-current specimens, and 4: isotopic signatures in the invertebrates
change temporally as a result of variations in available food sources). Degrees of freedom was 1 for each model term, except for the residuals (df =
39, 37 and 40 for residuals in barnacles (T. serrata), mussels (P. perna) and polychaetes (G. gaimardi), respectively); F = F ratio; * denotes a
significant effect.
Tetraclita serrata
δ13C
Model term
region
month
site
region*month
region*site
month*site
region*month*site
F
12.2
40.9
8.9
0.0
1.5
0.4
0.2
p
<0.01*
<0.001*
<0.01*
0.97
0.23
0.56
0.69
δ15N
F
3.8
1.4
3.6
2.5
19.9
0.8
0.0
p
0.06
0.24
0.06
0.12
<0.001*
0.36
0.89
F
49.7
0.0
35.8
9.3
7.2
0.6
1.0
Gunnarea gaimardi
δ13C
δ15N
p
F
p
<0.001*
4.1
0.04*
0.96
3.3
0.08
<0.001*
8.4
<0.01*
<0.01*
1.0
0.32
0.01*
0.3
0.57
0.43
0.3
0.57
0.32
2.1
0.16
Perna perna
δ13C
F
117.3
4.7
0.0
7.5
1.3
0.0
0.0
p
<0.001*
0.04*
0.92
0.01*
0.27
0.82
0.94
δ15N
F
2.2
0.3
2.6
3.4
1.1
0.3
2.6
p
0.15
0.59
0.12
0.07
0.30
0.57
0.11
2
Supplemental Table S3. Suspended particulate matter. General linear model output for
testing regional and site effects on carbon isotope signatures, and regional, site and time
effects on nitrogen signatures. F = F ratio; * denotes a significant effect.
Model term
region
site
region*site
residuals
df
1
1
1
12
δ13C - March
F
p
124.1
<0.001*
5.2
<0.05*
42.7
<0.001*
δ13C - July
F
p
12.7
<0.01*
0.0
0.88
13.2
<0.01*
δ15N
region
month
site
region*month
region*site
month*site
region*month*site
residuals
1
1
1
1
1
1
1
22
2.2
57.5
15.5
12.1
22.0
1.4
1.1
0.15
<0.001*
<0.001*
<0.01*
<0.001*
0.25
0.30
3