Table 2 Impact of directional scenarios of species extinction on the functional richness within fish assemblages of lakes, rivers, and estuaries.

System type	Region/categories	Number of sites	Abundance-based scenario		Trait-based scenario		IUCN-based scenario
System type	Region/categories	Number of sites	SES AUC	P-value	SES AUC	P-value	SES AUC	P-value
Lakes	all	302	0.40	>0.999	0.65	>0.999	0.40	>0.999
	Danubian	255	0.47	>0.999	0.71	>0.999	0.21	>0.999
	Iberian	47	0.00	0.448	0.33	0.995	0.06	0.702
	small	99	0.40	>0.999	0.64	>0.999	0.44	>0.999
	large	203	0.40	>0.999	0.66	>0.999	0.38	>0.999
Rivers	all	869	−0.40	<0.001	−0.31	<0.001	−0.42	<0.001
	Danubian	394	−0.46	<0.001	−0.16	<0.001	−0.16	<0.001
	Iberian	475	−0.35	<0.001	−0.43	<0.001	−0.47	<0.001
	HWS	240	−0.31	0.001	−0.11	0.482	−0.60	<0.001
	MGR	305	−0.50	<0.001	−0.16	0.032	−0.18	0.012
	LLR	41	−0.51	0.008	−0.73	<0.001	−0.42	0.003
	MES	283	−0.36	<0.001	−0.57	<0.001	−0.49	<0.001
Estuaries	all	49	−1.22	<0.001	0.30	0.983	−0.14	0.295
	Danubian	28	−1.87	<0.001	0.01	0.566	−0.08	0.374
	Iberian	21	−0.35	0.064	0.69	0.997	−0.16	0.294
	small	37	−1.16	<0.001	0.24	0.934	−0.22	0.187
	large	12	−1.39	0.031	0.49	0.935	0.03	0.661

For each aquatic system and its associated categories and regions, the mean values of the Standardised Effect Size of Area Under the Curve (SES AUC) were calculated from the abundance-based, the trait-based and the IUCN-based scenarios. Negative SES AUC values indicate assemblages in which the functional diversity is more impacted by directional scenarios compared to random trajectories of species extinction. P-values indicate if the SES AUC values of directional scenarios were significantly lower than zero, based on unilateral Wilcoxon rank tests. Values in bold indicate P-value < 0.05. For each aquatic system, the number of sites is reported for the total set (all), along with for their associated biogeographical region (Danubian and Iberian) and categories (small and large; headwater streams - HWS, medium gradient rivers - MGR, lowland rivers - LLR, and Mediterranean streams - MES).

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