Round goby and zebra mussel interactions with darters in a warm-water stream community in southern Michigan, USA

Figures & data

Figure 1. Map of the Flint River showing location in Michigan (black star) and the two sampling sites (black circles), Goldenrod Park (with round gobies and zebra mussels) and the Norway site (without round gobies and zebra mussels).

Table 1. Density (no./100 m²) of darter species and round gobies at Goldenrod Park (1998 and 2002) in the Flint River, Michigan and at the Norway site upriver of the study site where round gobies and zebra mussels were absent.

	Goldenrod Park		Norway Site
Species	1998	2002	2002
Blackside darter	1.2	10.2	3
Greenside darter	0	0	2
Johnny darter	<1	0	6
Rainbow darter	<1	0	1
Round goby	29.0	77.5	0

Data from 1998 from Carman et al. (2006). Other fish species collected were excluded.

Table 2. Percent composition by number (N) and volume (V) of diets of large (LG) and small (SM) round gobies (RG) Neogobius melanostomus and blackside darters (BD) Percina maculata collected during August 1998 and late August - September 2002 from the Flint River, Michigan at Goldenrod Park (GR) and the Norway site (NW).

	GR: 1998		GR: 2002				NW:2002
Parameter	BD (V)	RG (N)	BD (V)	SM RG (V)	LG RG (N)	LG RG (V)	BD (V)	GD (V)	JD (V)	RD (V)
Anisoptera			6	2	1	3
Amphipoda							20	55
Chironomidae	53	89	21	43	37	19	40	45	97	15
Corixidae							20
Dreissena polymorpha				2	4	9
Ephemeroptera	32		4	4	3	4				45
Gastropoda				6	22	12
Heptageniidae										25
Hydrophychidae	2	10	12	10	9	6	20		2	15
Ostrocoda			1	8	6	1
Plecoptera			3	2	1	3
Trichoptera	2		2	3	5	6
Zygoptera	10		42	5	6	11
Unidentified food			9	7	3	11			1
Miscellaneous	2	3	1	7	3	15
Sample size	13	70	64	371	110	110	6	3	11	2
Mean length (SE)	59 (2.3)	75 (1.0)	57 (1.2)	36 (0.4)	75 (0.9)	75 (0.9)	52 (2.0)	77 (2.0)	68 (1.9)	72 (2.8)
Range TL (mm)	46–75	51–97	41–74	18–53	54–104	54–104	40–70	74–82	63–73	68–76

Also included were diets of blackside, Johnny (Etheostoma nigrum) (JD), greenside (E. blennoides) (GD), and rainbow (E. caeruleum) (RD) darters collected at the Norway (NW) site. Trichoptera includes all families except Hydropsychidae. For Norway darter diets, Ephemeroptera excluded Heptageniidae, while for remaining fish, Heptageniidae was included in Ephemeroptera. Miscellaneous food included: Bluegill; brachycentrids; coleopterans; corixids; Daphnia spp.; Diptera pupae; dytiscids; elmids; Gammarus spp.; harpacticoid copepods; heptageniids; Helisoma spp.; hydracarinids; isopods; lepidopterans; Lepomis spp.; limnephilids; limpets; spotfin shiners; simuliids; Sialis spp.; tipulids; unidentified amphipods, insects, pupae, fish and plants. Samples include fishes with empty stomachs. Percentages may not sum to 100% due to rounding error. Also included is mean length (SE) and range of fishes collected.

Table 3. Schoener Index (SI - diet overlap) and Analysis of Similarity (ANOSIM) values for various comparisons of benthos data on rocks (ANOSIM values only) and diet of round gobies (RG) and blackside darters (BD) of different sizes and from different years. GR = Goldenrod Park, LG = large, SM = small, na = not applicable.

Comparison	SI	R - p	R -statistic
GR Benthos: 1998 versus 2002	na	0.001	0.95
Benthos: GR versus Norway	na	0.001	0.92
LG RG 1998 versus LG RG 2002	0.27	0.001	0.15
BD 1998 versus BD 2002	0.39	0.007	0.19
SM RG 2002 versus LG RG 2002	0.65	0.001	0.15
BD 2002 versus SM RG 2002	0.55	0.001	0.24
BD 2002 versus LG RG 2002	0.59	0.001	0.11

Table 4. List of the mean number of benthic organisms (standardized to 100/rock) found on rocks during 1998 (n = 135, pooled data over 4 months) (Carman et al. 2006) and 2002 (n = 7 per site, this study). Rocks were removed from Goldenrod Park (Goldenrod) and the Norway site upriver in the Flint River, Michigan. Rocks from 2002 were collected on 30 August (n = 3 per site) and 27 September 2002 (n = 4 per site) and data pooled.

	1998	2002
Taxa	Goldenrod	Goldenrod	Norway
Amphipoda	0	0.3	0.5
Anisoptera	0	0	0.2
Chironomidae	82.99	49.7	7.8
Coleoptera*	0	0.6	1.1
Corixidae	0.05	0	0
Diptera*	0.05	0.4	0.3
Dreissenidae	0	6.7	0
Elmidae	0.2	1.5	1.4
Ephemeroptera*	3.1	4.7	2.9
Heptageniidae	0.2	1.5	14.8
Hydropsychidae	3	27.4	52.5
Megaloptera	0.1	0	0
Oligochaeta	0	0	0.2
Orthoptera	0.05	0	0
Planaria	0	0	0.3
Plecoptera	0.05	0	0
Psephenidae	0	0.4	0
Sphaeriidae	0	0	0.3
Tipulidae	0	0	0.5
Trichoptera*	10.19	2.2	17.1
Zygoptera	0.05	4.7	0.2
Total no. rocks	135	7	7
Mean total no.	43	98	90

*Diptera taxa exclude Chironomidae, Ephemeroptera taxa exclude Heptageniidae, Trichoptera taxa exclude Hydropsychidae and Coleoptera taxa exclude Elmidae.

Carman S, Janssen J, Jude D, Berg M. 2006. Diel interactions between prey behaviour and feeding in an invasive fish, the round goby, in a North American river. Freshw Biol. 51(4):742–755.

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