Effect of spirotetramat and 2,4-dichlorophenoxyacetic pesticides on two phytoplankton species (Monoraphidium griffithii and Coscinodiscus sp.) in a single and compound mixture laboratory exposure

Figures & data

Table 1. Chemical composition of the culture solution (bold medium) modified from Barberousse (2006)

	Products	Nominal concentration of stock solution (g L^−1)	Nominal concentration in experiment (mgL^−1)
Stock solution A	NaNO3	25	0.25
	CaCl2,2H2O	2.5	0.025
	MgSO4,7H2O	7.5	0.075
	FeEDTA	2	0.02
Stock solution B	K2HPO4	7.5	0.075
	KH2PO4	17.5	0.175
	NaCl	2	0.02
Stock trace solution	H3BO3	2.4	0.0024
	MnCl2,4H2O	1.8	0.0018
	(NH4)6Mo7O24,4H2O	0.02	0.00002
	ZnSO4,7H2O	0.22	0.00022
	CuSO4,5H2O	0.08	0.00008
	CoNO3	0.09	0.00009
(For diatoms only)	Na2SiO3+ H2O		0.842 (Si concentration)

Table 2. Highest cell density and chlorophyll-a concentrations in Monoraphidium griffithii and Coscinodiscus sp. cultures for the various treatments

	Control	Spirotetramat D1	Spirotetramat D2	2,4-D D1	2,4-D D2	Compound mixture
M. griffithii
CCell (cells L^−1)	50.6x10^4 ± 145664^a	47.3x10^4 ± 106734^a	42.9x10^4 ± 85531^b	47.5x10^4 ± 46715^b	42.1x10^4 ± 108851^b	42.9x10^4 ± 115647^b
CChl-a (µg mL^−1)	3.76 ± 0.4^a	3.29 ± 2.3^a	4.73 ± 0.7^a	2.82 ± 1.7^a	4.49 ± 2.6^a	3.89 ± 0.7^a
Coscinodiscus sp.
CCell (cells L^−1)	3.59x10^4 ± 8748^a	3.23x10^4 ± 5691^b	3.18x10^4 ± 8141^b	3.21x10^4 ± 6699^b	1.96x10^4 ± 7369^c	3.07x10^4 ± 2357^b
CChl-a (µg mL^−1)	0.125 ± 0.02^a	0.112 ± 0.01^a	0.121 ± 0.02^a	0.112 ± 0.03^a	0.120 ± 0.02^a	0.117 ± 0.01^a

All data are given in the form of mean ± standard deviation. D1 and D2 are standing, respectively,for low and high applied concentration. Values of the same line with different superscripts are significantly different (One-way ANOVA, Tukey honesty test, p < 0.05). CCell: Cell density; CChl-a: Chlorophyll-a concentration.

Figure 1. Cell density and Chlorophyll-a concentration in Monoraphidium griffithii cultivated under six different conditions (five polluted environments and one control). Lines and symbols indicate cell density, bars indicate chlorophyll-a concentration. Error bars indicate average ± standard deviation

Figure 2. Cell density and Chlorophyll-a concentration in Coscinodiscus sp. cultivated under six different conditions (five polluted environments and one control). Lines and symbols indicate cell density; bars indicate chlorophyll-a concentration. Error bars indicate average ± standard deviation

Figure 3. Phytoplankton cell size classes (CI-CIII, C1-C3) obtained from cluster analysis for the different treatments. (A): sizes identified for M. griffithiitreatments; (B): sizes identified for Coscinodiscus sp. treatments. l is length, d is diameter

Figure 4. Occurrence of cell size classes in Monoraphidium griffithii for the various treatments. CI includes cells of 52.6–70 µm in length (small cell size), CII cells of 70–80 µm in length (moderate cell size), and CIII cells of 80–89 µm in length (large cell size). D1 and D2 indicate low and high concentrations, respectively. Cont = control, Spiro = spirotetramat. Error bars indicate average ± standard deviation

Figure 5. Occurrence of cell size classes in Coscinodiscussp. for the various treatments. C1 includes cells of 42.3–52.5 µm in diameter (small cell size), C2 cells of 52.3–64.7 µm in diameter (moderate cell size), and C3 cells of 64.7–76.5 µm in diameter (large cell size). D1 and D2 indicate low and high concentrations, respectively, Cont = control, Spiro = spirotetramat. Error bars indicate average ± standard deviation

Barberousse, H. (2006). Etude de la diversité des algues et des cyanobactéries colonisant les revêtements de façade en France et recherche des facteurs favorisant leur implantation. Ecologie, Environnement. Museum national d’histoire naturelle - MNHN PARIS.

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