Table 6. Species responsible for discrimination of macrofauna between two bottom types, as indicated by the SIMPER procedure, based on presence/absence data.

	SIMPER		JAS		RM
	Diss/SD	Cont%	bare	veg	bare	veg
Idotea chelipes	2.25	6.98	8	100	0	76
Idotea balthica	2.00	6.90	12	76	0	96
Mytilus edulis	1.73	6.49	24	96	16	92
Bryozoa nd	1.42	5.79	4	60	4	80
Theodoxus fluviatillis	1.23	5.19	40	100	32	80
Chironomidae larvae	1.11	4.78	44	88	40	92
Gammarus oceanicus	1.10	4.45	8	68	0	44
Corophium sp. juv.	0.98	4.18	72	72	36	28
Marenzelleria neglecta	0.98	4.15	84	64	16	28
Lymnaea peregra	0.96	4.00	32	76	16	20

Diss/SD - average contribution to overall dissimilarity divided by standard deviation, Cont% - percentage contribution to total dissimilarity. Mean frequencies of occurrence [%] in groups of samples defined by bottom type (bare, veg) and station (JAS, RM) are presented. Only species of cont% equal or higher than 4 are listed.