Fig. 4

Two-dimensional nMDS ordinations of sites (a) and species (b) based on Jaccard similarities coefficient calculated on the presence/absence data of spionid fauna. Correlations between the ordination and environmental (a) or habitat type (b) vectors with p value < 0.01, < 0.05, and ≥ 0.05 are indicated by solid, dashed, and dotted lines of arrows, respectively, with the length of the arrows corresponding to the correlation strength. Complete overlap of the data points in nMDS ordinations are indicated by fisheye symbols. Site T is excluded from the analysis due to inadequate data without any spionid species. The data points of nMDS ordinations of species (b) are indicated by abbreviated species names: Po. cal = Polydora calcarea, Po. ona = Polydora onagawaensis, Po. has = Polydora haswelli, Po. hop = Polydora hoplura, Po. web = Polydora websteri, D. arm = Dipolydora armata, D. gia = Dipolydora giardi, D. bid = Dipolydora bidentata, B. ham = Boccardiella hamata, B. pro = Boccardia proboscidea, B. pse = Boccardia pseudonatrix, Ps. tsu = Pseudopolydora tsubaki, C. spo = Carazziella spongilla, Po. daw = Polydorella dawydoffi, Po. cor = Polydora cornuta, Ps. ach = Pseudopolydora achaeta, Ps. kem = Pseudopolydora cf. kempi, Ps. pau = Pseudopolydora paucibranchiata, Ps. ret = Peudopolydora cf. reticulata, S. fil = Spio aff. Filicornis, R. glu = Rhynchospio glutaea complex sp., S. bom = Spiophanes aff. bombyx, A. oxy = Aonides oxycephala, Pa. pat = Paraprionospio patiens, Pr. jap = Prionospio japonica, Pr. kru = Prionospio krusadensis