Effects of an anthropogenic saltwater inlet on three-spined stickleback (Gasterosteus aculeatus) (Teleostei: Gasterosteidae) and their parasites in an inland brook

Figures & data

Table I. Water temperature and conductivity in the coal mine drainage water, above (fresh water) and 2 km below (salt water) the inlet of the drainage water and the fold change caused by the inlet. Samplings were performed monthly from April to October in 2010, each between 10 and 12 a.m.

	Coal mine drainage		Fresh water		Salt water		Fold change
	°C	µS cm^−1	°C	µS cm^−1	°C	µS cm^−1	°C	µS cm^−1
Apr	15.9	43,800	8.9	670	14.4	22,400	1.6	33.4
May	16.7	44,000	10.6	660	14.3	24,700	1.4	37.4
Jun	19.7	39,700	16.4	532	14.4	22,400	0.9	42.1
Jul	22.8	47,300	20.9	577	21	32,200	1.0	55.8
Aug	20.2	43,700	18.4	484	18.3	22,600	1.0	46.7
Sep	19	43,800	14.7	638	15.7	8100	1.1	12.7
Oct	16.6	48,900	9.6	670	11.9	19,500	1.2	29.1

Figure 1. Body condition index (BCI, mean ± standard error) of adult 1+ (filled triangle) and juvenile 0+ (open triangle) sticklebacks from the 2010 samplings in (A) the freshwater habitat and (B) the saltwater habitat of the brook Ibbenbürener Aa; * = p < 0.05 between habitat at given time point, *) = p < 0.05 from previous time point.

Table II. Growth performance of juvenile sticklebacks in the Ibbenbürener Aa over the study period from April to October 2010: initial and final body wet weight (mean ± standard error), absolute growth, and relative and specific growth rates (RGR and SGR) of juvenile sticklebacks from both habitats over the whole observation period. Numbers of investigated specimens are given in parentheses (n).

Habitat	Initial weight* (mg)	Final weight (mg)	Absolute growth (mg)	RGR (%)	SGR (%/d)
Freshwater	231 ± 53 (14)	712 ± 88 (24)	481 ± 74	209	0.75
Saltwater	93 ± 9 (5)	1018 ± 104 (33)	924 ± 97	992	1.33

* Note: in the saltwater habitat juvenile sticklebacks were caught earliest in May, while juveniles were caught earliest in June in the freshwater habitat.

Table III. Specific growth rates (SGR, %/d) of juvenile sticklebacks between monthly sampling intervals in the Ibbenbürener Aa in 2010. Numbers of investigated specimens are given in parentheses (n).

Habitat	May–June	June–July	July–August	August–September	September–October
Freshwater	N/A	+0.98 (23)	+0.4 (19)	−0.68 (20)	+1.13 (24)
Saltwater	+4.52 (19)	+1.91 (18)	+1.05 (17)	+0.17 (20)	−1.32 (33)

N/A = not applicable.

Table IV. Parasite infection. Prevalence (%) and mean intensity (± standard error) of parasite species in the saltwater (salt) and freshwater (fresh) habitats of the Ibbenbürener Aa in 2010.

	April		May		June		July		August		September		October
	Fresh	Salt	Fresh	Salt	Fresh	Salt	Fresh	Salt	Fresh	Salt	Fresh	Salt	Fresh	Salt
Gyrodactylus sp.	87.5	87.5	87.5	100	10	73.3	20	60	–	50	50	100	40	50
	17 ± 8.5	6.4 ± 1.3	38 ± 14.7	26.8 ± 8.2	12 ± 1.2	4.3 ± 0.9	2 ± 0.3	3.3 ± 0.9	–	1.8 ± 0.4	1.6 ± 0.3	5.7 ± 1.6	4.5 ± 1.5	1.2 ± 0.2
Trichodina sp.	12.5	–	37.5	15.4	–	20	–	–	50	–	90	50	100	40
	25 ± 3.1	–	25 ± 4.6	5 ± 0.5	–	5 ± 0.5	–	–	9 ± 2.4	–	66.7 ± 10	9 ± 2.4	41.5 ± 13.1	10 ± 2.4
Glochidia (Unio sp.)	75	–	12.5	–	–	–	–	–	–	–	–	–	–	–
	33.3 ± 10.1	–	2 ± 0.3	–	–	–	–	–	–	–	–	–	–	–
Piscicola geometra	–	–	50	–	–	–	–	–	–	–	–	–	–	–
	–	–	1.5 ± 0.4	–	–	–	–	–	–	–	–	–	–	–
Contracaecum sp.	50	62.5	50	46.2	10	46.7	10	40	50	10	20	30	20	70
	2.5 ± 0.6	2.3 ± 0.7	2.5 ± 0.5	4.2 ± 0.7	5 ± 0.5	2.6 ± 0.6	1 ± 0.1	4.5 ± 0.8	1.6 ± 0.4	7 ± 0.7	2 ± 0.3	3 ± 0.4	1 ± 0.1	2.3 ± 0.5
Proteocephalus filicollis	–	12.5	–	–	–	6.7	–	–	–	–	10	–	–	–
	–	1 ± 0.1	–	–	–	1 ± 0.1	–	–	–	–	1 ± 0.1	–	–	–
Acanthocephalus lucii	–	–	65.5	–	10	–	–	–	–	–	–	–	–	–
	–	–	1.2 ± 0.3	–	2 ± 0.2	–	–	–	–	–	–	–	–	–
Schistocephalus solidus	–	–	–	–	–	–	–	–	–	10	10	–	–	–
	–	–	–	–	–	–	–	–	–	1 ± 0.1	1 ± 0.1	–	–	–
Raphidascaris acus	–	–	–	–	–	–	–	10	–	–	–	10	–	–
	–	–	–	–	–	–	–	1 ± 0.1	–	–	–	2 ± 0.2	–	–
Anguillicola crassus	–	–	–	–	–	–	–	–	–	–	20	–	–	–
	–	–	–	–	–	–	–	–	–	–	1 ± 0.1	–	–	–
Trypanosoma sp.	–	–	–	–	20	–	–	–	10	–	–	10	–	–
	–	–	–	–	30 ± 4.3	–	–	–	100 ± 10.0	–	–	50 ± 5.0	–	–
No. adult sticklebacks	6	8	8	8	1	10	–	5	1	1	–	–	–	–
No. juvenile sticklebacks	–	–	–	5	6	6	10	5	9	9	10	10	10	10

Figure 2. Parasite index of adult (black triangle) and juvenile (open triangle) sticklebacks (mean ± standard error) collected in the Ibbenbürener Aa in 2010 from (A) the freshwater habitat and (B) the saltwater habitat; * = p < 0.05 between habitat at given time point, *) = p < 0.05 from previous time point.