Table 4. Abundance trends: most important taxa characterizing groups ‘I’,‘D’ and‘S’ by SIMPER analysis.

GROUP	Taxon	Average frequency of occurrence	Contribution (%)	Cumulative Sum (%)
D	T. min. capelanus	0.200	5.62	5.62
	S. scomber	0.290	5.33	10.95
	L. mormyrus	0.128	5.17	16.12
	Scorpaena spp.	0.151	4.86	20.98
	Z. faber	0.081	4.65	25.63
S	M. surmuletus	0.227	6.47	6.47
	Loligo spp.	0.116	5.64	12.11
	S. pilchardus	0.050	5.2	17.31
	Lophius spp.	0.062	5.17	22.48
	Trachurus spp.	0.089	5.09	27.57
I	S. cretense	0.583	10.45	10.45
	P. erythrinus	0.154	6.94	17.39
	S. officinalis	0.220	6.76	24.15
	A. antennatus	0.220	6.76	30.91
	Mullus spp.	0.537	6.46	37.37

The fish taxa are listed in decreasing order of their importance in typifying the groups ‘INCREASE’ (‘I’), ‘DECREASE’ (‘D’) and‘STABLE’ (‘S’) by SIMPER analysis performed on presence/absence data. Cut off for low contributions: 90.00%. ‘I’ vs‘D’ overall between group dissimilarity 81.34; ‘D’ vs‘S’ overall between group dissimilarity 79.07; ‘S’ vs‘I’ overall between group dissimilarity 82.66