Temperature and toxicity of the copper herbicide (Nautique^TM) to freshwater fish in field and laboratory trials

Figures & data

Figure 1. Map of Sleepy Hollow Lake showing sampling locations.

Notes: Circles = treatment sites; squares = reference sites. Sites 1–6 are 2013 sites; Sites 1, 2, 7, & 8 are 2014 sites.

Figure 2. Diagram illustrating position of fish cages in 2013 field trials.

Table 1. Lethal concentrations to 50% [and 95% CI] of test fish at various times for tested herbicides. Eight hour results for brook trout and six hour results for fathead minnow tests. Copper sulfate and Captain^TM results previously reported in Closson and Paul (2014)

Species	Formulation	Lethal concentrations (mg Cu/L)
		6 h/8 h	24 h	48 h	72 h	96 h
Brook trout (13°C)	Copper sulfate	>1.00	0.41 (0.36–0.45)	0.26 (0.24–0.28)	0.25 (0.23–0.27)	0.25 (0.23–0.27)
	Captain^TM	0.84 (0.77–0.92)	0.32 (0.29–0.36)	0.21 (0.18–0.24)	0.19 (0.16–0.21)	0.18 (0.16–0.21)
	Nautique^TM	>40.0	32.5 (28.5–37.7)	28.8 (27.6–30.1)	28.5 (27.5–29.6)	28.2 (26.7–29.7)
Fathead minnow (22°C)	Copper sulfate	0.90 (0.78–1.02)	0.60 (0.55–0.65)	0.44 (0.39–0.51)	0.34 (0.29–0.39)	0.28 (0.25–0.33)
	Captain^TM	>6.40	1.04 (0.90–1.20)	0.90 (0.77–1.04)	0.81 (0.69–0.94)	0.69 (0.59–0.81)
	Nautique^TM	34.3 (33.3–35.4)	28.8 (27.9–29.8)	28.0 (27.1–28.9)	26.9 (26.1–27.8)	24.4 (23.9–24.9)
Fathead minnow (28°C)	Nautique^TM	35.2 (34.0–36.4)	29.0 (27.8–30.3)	24.7 (23.8–25.5)	21.5 (20.5–22.6)	19.7 (18.7–20.8)

Table 2. Effective concentrations to 50% [95% CI] of test fish. Eight hour results for brook trout and six hour results for fathead minnow tests. Copper sulfate and Captain^TM results from Closson and Paul (2014)

Species	Formulation	Effective concentrations (mg Cu/L)
		6 h/8 h	24 h	48 h	72 h	96 h
Brook trout (13°C)	Copper sulfate	0.58 (0.52–0.64)	0.27 (0.24–0.30)	0.22 (0.20–0.25)	0.21 (0.18–0.23)	0.20 (0.18–0.24)
	Captain^TM	0.84 (0.77–0.88)	0.24 (0.22–0.26)	0.23 (0.20–0.26)	0.21 (0.17–0.25)	0.18 (0.16–0.21)
	Nautique^TM	>40.0	29.6 (27.6–31.8)	28.0 (25.3–30.9)	26.5 (24.7–28.5)	26.2 (24.3–28.2)
Fathead minnow (22C)	Copper sulfate	0.71 (0.64–0.79)	0.52 (0.47–0.58)	0.35 (0.30–0.40)	0.25 (0.21–0.28)	0.20 (0.18–0.23)
	Captain^TM	2.63 (2.30–3.02)	1.01 (0.87–1.17)	0.90 (0.77–1.04)	0.81 (0.69–0.94)	0.68 (0.58–0.80)
	Nautique^TM	32.4 (31.4–33.4)	28.2 (27.3–29.1)	26.4 (25.5–27.3)	24.6 (23.9–25.4)	23.0 (22.3–23.7)
Fathead minnow (28C)	Nautique^TM	35.2 (34.0–36.4)	26.4 (25.5–27.3)	23.7 (23.0–24.5)	20.3 (19.4–21.2)	19.6 (18.7–20.6)

Figure 3. Mortality percentages in response to Nautique^TM, Captain^TM and copper sulfate concentrations at 22°C for fathead minnows and 13°C for brook trout. (a) Fathead minnow mortality at 24 h; (b) Brook trout mortality at 24 h; (c) Fathead minnow mortality at 96 h; (d) Brook trout mortality at 96 h.

Table 3. Output from models examining the relative lethal and effective toxicities of three copper formulations on brook trout and fathead minnows. Time and concentration were also included in the models. Effects of Captain^TM and copper sulfate are given in comparison with Nautique^TM

	% ±SE (95% CI)	χ^2	p-value
Brook trout
Lethal
Captain vs. Nautique (%)	25.6 ± 2.0 (21.8–29.8)	949.4	<0.0001
Copper sulfate vs. Nautique (%)	25.2 ± 2.0 (21.2–29.2)	585.7	<0.0001
Concentration (mg Cu/L)	2.0 ± 0.2 (1.7–2.3)	873.6	<0.0001
Time (h)	0.03 ± 0.0 (0.03–0.04)	610.8	<0.0001
Effective
Captain vs. Nautique (%)	4.5 ± 0.7 (3.5–6.1)	698.5	<0.0001
Copper sulfate vs. Nautique (%)	4.2 ± 0.7 (3.2–5.8)	504.9	<0.0001
Concentration (mg Cu/L)	0.5 ± 0.1 (0.4–0.8)	725.8	<0.0001
Time (h)	0.03 ± 0.0 (0.02–0.03)	417.1	<0.0001
Fathead minnow
Lethal
Captain vs. Nautique (%)	4.9 ± 0.2 (4.5–5.2)	1,628.6	<0.0001
Copper sulfate vs. Nautique (%)	5.9 ± 0.2 (5.5–6.2)	2,205.3	<0.0001
Concentration (mg Cu/L)	0.6 ± 0.0 (0.6–0.7)	2,854.9	<0.0001
Time (h)	0.03 ± 0.0 (0.03–0.03)	837.5	<0.0001
Effective
Captain vs. Nautique (%)	4.8 ± 0.2 (4.5–5.2)	1,666.9	<0.0001
Copper sulfate vs. Nautique (%)	5.9 ± 0.2 (5.5–6.3)	2,315.9	<0.0001
Concentration (mg Cu/L)	0.7 ± 0.0 (0.6–0.7)	2,987.4	<0.0001
Time (h)	0.03 ± 0.0 (0.03–0.03)	770.2	<0.0001

Figure 4. Change over time of log (copper) after treatment at the treatment sites. Regression line based on simple linear model. Parameter estimates given in the text are based on random effects model accounting for repeated measures at each site.

Figure 5. Proportional survival of fish in reference sites (solid line) and treatment sites (dashed line).

Closson, K. R., & Paul, E. A. (2014). Comparison of the toxicity of two chelated copper algaecides and copper sulfate to non-target fish. Bulletin of Environmental Contamination and Toxicology, 93, 660–665.10.1007/s00128-014-1394-3

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