Table 3 Permutation test results evaluating acoustic backscatter from krill and silverfish, at ice edge and interior as affected by depth, 14 December 2014 to 7 January 2015.

From: Drivers of concentrated predation in an Antarctic marginal-ice-zone food web

Depth Interval

Krill

Silverfish

p-value

location of greater backscatter

p-value

location of greater backscatter

0–10 m

0.19

—

0.16

—

10–20 m

0.04**

interior

0.06*

edge

20–30 m

0.04**

interior

0.04**

edge

30–40 m

0.07*

interior

0.13

—

40–50 m

0.48

—

0.43

—

50–60 m

0.21

—

0.65

—

60–70 m

0.05*

edge

0.77

—

70–80 m

0.19

—

0.58

—

80–90 m

0.42

—

0.58

—

90–100 m

0.40

—

0.56

—

  1. Shown are p-values found using eqn. 1 (Methods), where an even distribution of prey would produce a value of 0.5. Significance at the 95% level is indicated by **, and marginal significance at the 90% level is indicated by *. Edge and Interior locations indicate sampling from stations found along the fast ice edge or interior (>1 km from the fast ice edge), respectively (Fig. 1). Comparisons below 100 m were not calculated due to declining detectability with depth, and high variance of abundance.
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