Effects of local, river-network and catchment factors on fish assemblages in the headwater streams of the Xin'an basin, China

Figures & data

Figure 1. Map of the Xin'an basin in the Anhui Province, China. Solid circles marked the 91 sampling sites.

Table 1. Summary statistic for predictor variables measured for local habitat, tributary spatial position, and catchment landscape condition.

Variable	Abbrev.	Min.	Max.	Mean	SD	CV
Local habitat
Elevation (m)	El	109	444	205.6	73.4	0.36
Dissolved oxygen (mg/L)	DO	2.27	13.85	7.53	1.99	0.26
Water temperature (°C)	WT	18	33.8	26.3	4.7	0.18
Conductivity (mS/cm)	Co	18.3	335.1	100	64.2	0.64
Wetted width (m)	WW	2.5	120	13.41	16.17	1.21
Water depth (m)	WD	0.06	1.0	0.3	0.2	0.62
Current velocity (m/s)	CV	0.07	0.62	0.24	0.13	0.56
Substrate coarseness	SC	1	5.8	3.6	1.1	0.29
Substrate heterogeneity	SH	0	1.91	1.13	0.42	0.37
Slope (‰)	Sl	0.34	47.43	13.43	10.64	0.79
Tributary spatial position
Stream order	Order	1	3	1.5	0.6	0.44
Link magnitude	Link	1	13	2.2	2.4	1.12
Confluence link	C-link	3	43	22	11	0.50
Downstream link	D-link	2	130	10	22	2.2
Distance from headwater (m)	DH	10	12333	2709	2422	0.89
Distance from mouth (m)	DM	9594	204784	89161	47464	0.53
Land-use area
Forest area (%)	FA	5.12	98.96	52.37	23.0	0.44
Meadow area (%)	MA	0.89	65.16	27.75	13.28	0.48
Agriculture area (%)	AA	0.10	36.53	11.46	8.71	0.76
Wetland area (%)	WA	0.02	20.60	3.69	3.66	0.99
Urbanization area (%)	UA	0.01	29.69	4.72	5.23	1.11

Table 2. Species composition, the frequency of occurrence (F) and relative abundance (RA) for fishes collected in the headwater streams of the Xin'an basin.

Species	Code	F (%)	RA (%)
CYPRINIFORMES
Cyprinidae
Zacco platypus	ZAP	86.81	24.87
Acrossocheilus fasciatus	ACF	82.42	14.14
Phoxinus oxycephalu	PHO	2.20	0.12
Varicorhinus barbatulus	VAB	6.59	0.21
Acheilongnathus gracilis	ACG	4.40	0.31
Parasinilabeo assimilis	PAA	1.10	0.01
Abbottina rivularis	ABR	15.38	1.17
Platysmacheilus exiguus	PLE	3.30	0.05
Sarcocheilichthys nigripinnis	SAN	3.30	0.39
Saurogobio dabryi	SAD	1.10	0.03
Microphysogobio fukiensis	MIF	6.59	0.31
Sarcocheilichys parvus	SAP	24.18	3.74
Pseudorasbora parva	PSP	13.19	0.56
Rhodeus ocellatus	RHO	23.08	2.72
Squalidus argentatus	SQA	21.98	1.41
Gnathopogon taeniellus	GNT	3.30	0.07
Opsariichthys bidens	OPB	21.98	1.25
Carassius auratus	CAA	13.19	0.33
Cobitidae
Misgurnus anguillicaudatus	MIA	40.66	3.05
Leptobotia taeniaps	LET	4.40	0.24
Cobitis sinensis	COS	19.78	0.63
C. rarus	COR	36.26	4.54
Parabotia fasciata	PAF	17.58	0.73
Vanmanenia stenosoma	VAS	63.74	14.65
PERCIFORMES
Gobiidae
Ctenogobius spp.	CTS	74.73	21.26
Mastacembelidae
Mastacembelus aculeatus	MAA	6.59	0.25
Channidae
Channa argus	CHA	2.20	0.03
Eleotridae
Hypseleotris swinhonis	HYS	3.30	0.17
Odontobutis obscurus	ODO	37.36	2.09
SILURIFORMES
Amblycipitidae
Liobagrus styani	LIS	2.20	0.03
Bagridae
Pseudobagrus truncatus	PST	20.88	0.39
SYNBGRANCHIFORMES
Synbranchidae
Monopterus albus	MOA	9.89	0.13
CYPRINODONTIFORMES
Cyprinodontidae
Oryzias latipes	ORL	2.20	0.13

Table 3. Effects of environmental factors on fish species richness based on stepwise linear regression.

Environment types	Environmental variables	β	t	p	R^2
Local habitat	Water temperature	0.30	2.83	**	0.30
	Slope	−0.28	−2.76	**	0.30
	Conductivity	0.28	2.62	**	0.30
	Wetted width	0.22	2.08	*	0.30
Spatial position	Link magnitude	0.45	2.22	**	0.35
	Distance from mouth	0.28	3.22	**	0.35
Land use/cover	Urbanization area	0.60	2.11	*	0.12
Combinations	Distance from mouth	1.16	2.67	**	0.45
	Conductivity	0.30	2.60	**	0.45
	Confluence link	−0.92	−2.22	**	0.45

*p < 0.05 and **p < 0.01, respectively.

Figure 2. Spatial variations of fish assemblage structures across stream orders based on non-metric multi-dimensional scaling.

Figure 3. Redundancy analysis diagram for fish assemblage structures and significant environmental factors (a) local habitat; (b) tributary spatial position; (c) catchment landscape; (d) all environmental factors. Environmental variable and species codes as in Tables 1 and 2, respectively.