The Effect of Four Terrestrial Herbicides on the Productivity of Artificial Stream Algal Communities

Abstract

Artificial streams containing algal communities derived from a spring and an agriculturally impacted stream were used to assess the effect of 0.1, 1, and 10 mg kg−1 atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine], trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine), MSMA (monosodium methanearsonate), and paraquat (1,1′‐dimethyl‐4,4′‐bipyridylium cation) on the productivity (photosynthesis and respiration) of stream algae. The importance of induced resistance to the herbicides was evaluated by comparing the responses of the spring and stream algae and by determining if allowing the streams to be colonized for 3 weeks in the presence of 0.01 mg kg−1 of the herbicide under test would modify response by selecting for a more resistant flora. Productivity was measured by open‐water oxygen methods for 3 weeks before and 3 weeks after herbicide injection. The communities derived from both the spring and the stream were dominated by diatoms, and responded similarly to trifluralin, atrazine, and MSMA, but had divergent responses to paraquat. Trifluralin had no effect on productivity. Photosynthesis was significantly depressed by 1 and 10 mg kg−1 atrazine and by 10 mg kg−1 MSMA, and there were indications of a slight inhibition by 0.01 mg kg−1 atrazine. Paraquat at 10 mg kg−1 had little effect on the spring‐derived communities but caused severe inhibition of the stream‐derived algae. There was little evidence that exposure to 0.01 mg kg−1 herbicide during colonization modified the response of the algae to any of the herbicides.

Spatial and temporal variation of algal assemblages in six Midwest agricultural streams having varying levels of atrazine and other physicochemical attributes

“…As noted above, these sites are in general diatom dominated, particularly periphytic assemblages and both periphyton and phytoplankton during the spring, when atrazine concentrations are frequently elevated. Diatoms and cyanophyta have been shown to be less sensitive to atrazine than other algal groups, particularly compared to chlorophyta, which typically show the highest sensitivity to atrazine (Goldsborough and Robinson, 1986;Kosinski and Merkle, 1984;Guasch et al, 1997Guasch et al, , 1998Guasch et al, , 2007Dorigo et al, 2004;Guanzon et al, 1996;Tang et al, 1998;Brain et al, 2012aBrain et al, , 2012b. It could therefore be expected that diatomdominated communities such as those in this study would be less sensitive overall to atrazine.…”

“…These studies have generally concluded that significant effects on primary producers typically only begin to occur with prolonged atrazine concentrations N30 μg/L and that subsequent to any disturbances algal populations recover (Gruessner and Watzin, 1996;Nyström et al, 2000;Baxter et al, 2011;Huber, 1993;Solomon et al, 1996;Giddings, 2012). However, mesocosm studies testing atrazine concentrations N 50 μg/L for extended periods have shown decreased activity, abundance, or diversity, or shifts in algal community structure (Kosinski and Merkle, 1984;Hamala and Kollig, 1985;Larsen et al, 1986;Krieger et al, 1988;Hamilton et al, 1988;Hamilton and Mitchell, 1997;Nyström et al, 2000;Guasch et al, 2007).…”

Changes in periphytic algal community structure as a consequence of short herbicide exposures

“…Studies have examined the relative impacts of heavy metals (Williams & Mount, 1965;Dickman, 1974;Sigmon et al, 1977;Grolle & Kuiper, 1980), industrial effluent (Evans & Marcan, 1976;Moll & Keller, 1980) and pesticides (Anderson, 1981;Hodgson & Carter, 1982;Hodgson & Linda, 1984;Kosinski, 1984;Kosinski & Merckle, 1984) on dry weight and pigment concentration (Hodgson & Carter, 1982), physiological activity (Goldsborough & Robinson, 1983) and/or species composition (Kosinski, 1984;Leland & Carter, 1984) of artificial (Hodgson & Linda, 1984;Kosinski, 1984) or in situ (Goldsborough & Robinson, 1983) communities under a series of controlled treatments.…”

Biomass or growth rate endpoint for algae and aquatic plants: Relevance for the aquatic risk assessment of herbicides

“…In the second case, artificial streams were used to conduct studies with atrazine under constant exposure (Kosinski 1984;Kosinski and Merkle 1984). The constant exposure of 10 mg/L atrazine produced a change in primary production and biovolume of algae (effect class 4, RT ¼ 0.08).…”