Treatment

Yield of commercial clams (kg·m⁻²)

Site 1

Site 2

Site 3

Site 4

Site 5

Site 6

Z. japonica

2.2

0.7

1.0

1.2

0.5

5.1

No Z. japonica

3.9

1.3

1.5

2.6

1.2

7.6

T-test significance

0.02

0.04

0.3

0.03

0.007

0.05