Table 1 Characteristics of five sample station groups as classified by hierarchical clustering with group-average linking

Occurrence of benthic species (% present)

Arenicola marina (6 classes)

93

97

100

73

30

Cerastoderma edule (ind./m²)

91

78

40

55

100

Lanice conchilega (3 classes)

4

28

7

100

20

Diatoms (% bottom cover)

36

14

5

9

100

Zostera marina (% bott. cover)

85

8

2

–

–

Zostera noltii (% bottom cover)

91

5

2

–

–

Enteromorpha spp. (% bott. co.)

31

94

1

45

20

Ulva lactuca (3 classes)

35

82

1

18

80

Fucus spp. (3 classes)

8

8

5

10

–

Porphyra spp. (3 classes)

1

10

–

–

–

Salicornia europaea (3 classes)

3

–

–

–

–

Spartina anglica (3 classes)

7

1

–

–

–

Mytilus edulis (6 classes)

7

25

2

27

30

Sample means ± standard deviations of environmental data

Emersion time “dry” (%)

41 ± 17

21 ± 17

20 ± 19

8 ± 5

13 ± 14

τ ^mean_c (N/m²)

0.037 ± 0.026

0.069 ± 0.027

0.091 ± 0.041

0.099 ± 0.028

0.031 ± 0.005

τ ^max_c (N/m²)

0.28 ± 0.14

0.40 ± 0.16

0.55 ± 0.25

0.44 ± 0.12

0.19 ± 0.03

τ ^mean_w (N/m²)

0.25 ± 0.06

0.29 ± 0.05

0.30 ± 0.10

0.31 ± 0.07

0.26 ± 0.02

τ ^max_w (N/m²)

1.43 ± 0.21

1.51 ± 0.15

1.60 ± 0.32

1.61 ± 0.19

1.50 ± 0.04

10th percentile grain-size D₁₀ (μm)

85 + 100/−46

116 + 37/−28

138 + 61/−42

100 + 85/−46

41 + 42/−21

Median grain-size D₅₀ (μm)

156 + 86/−55

166 + 37/−30

201 + 59/−46

173 + 21/−19

72 + 70/−36

90th percentile grain-size D₉₀ (μm)

245 + 172/−101

235 + 76/−57

308 + 142/−97

274 + 83/−64

175 + 89/−59

Sediment grain-size sorting D₉₀/D₁₀

2.89 + 2.5/−1.3

2.04 + 0.7/−0.5

2.23 + 1.0/−0.7

2.74 + 2.8/−1.4

4.29 + 1.7/−1.2