TABLE 1.

Comparison of topological parameters of networks.

	Metacommunity		Sediment		Water
	Real	Random	Real	Random	Real	Random
Number of nodes	128	128	607	607	1,049	1,049
Number of edges	471	471	2,265	2,265	20,857	20,857
Average degree	7.359	7.359	7.463	7.463	39.765	39.765
Average path length	2.599	2.634 ± 0.012*	5.751a	3.413 ± 0.005*	3.518b	2.175 ± 0.001*
Diameter	8.000	4.869 ± 0.339*	17.000a	6.192 ± 0.396*	11.000b	3 ± 0*
Clustering coefficient	0.552	0.058 ± 0.007*	0.416a	0.013 ± 0.002*	0.488b	0.038 ± 0*
Centralization degree	0.226	0.06 ± 0.012*	0.059a	0.016 ± 0.002*	0.153b	0.02 ± 0.002*
Centralization betweenness	0.036	0.036 ± 0.009	0.212a	0.014 ± 0.002*	0.026b	0.001 ± 0*
Modularity	0.446	0.318 ± 0.011*	0.708a	0.336 ± 0.004*	0.445b	0.126 ± 0.002*

The differences between the real co-occurrence networks and their associated random networks (permutation = 999, values shown mean ± SD) were assessed using a Z-test (*indicates the significant differences of P < 0.05). The differences between sediment and water bacterial network were assessed using a t-test (different lowercase letters indicate the significant difference of P < 0.05).