Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

1

Carney, 1983; Kettle et al., 1987; 

deNoyelles et al., 1989; deNoyelles et 

al., 1994

500 365 Single Mesocoms, 

experimental 

ponds

Decrease in cover by emerged, floating, 

and submerged aquatic plants (>90% 

decline in Typha; 100% decline in 

SAV).

Macro > 1 yr (no recovery observed) From 805-d study where ponds formerly 

treated with formulated product at 20 μg/L 

were increased to 500 μg/L; exposure 

concentrations derived from graph during 

the second year of the study. 

Y

2

Carney, 1983; Kettle et al., 1987; 

deNoyelles et al., 1989; deNoyelles et 

al., 1994; deNoyelles and Kettle, 1980; 

Dewey, 1986

20 365 Single Mesocoms, 

experimental 

ponds

Decrease in cover by floating and 

submerged aquatic plants (40% decline 

in Typha; 50% decline in SAV; 50% 

decline in Najas).

Macro > 1 yr (no recovery observed) From 805-d study; study concentrations 

from first year of study. 

Y

3

deNoyelles et al., 1982; deNoyelles et 

al., 1989

500 63 Single Mesocoms, 

experimental 

ponds

Decrease (> 90% decline) in 

phytoplankton 14C-uptake and 

biomass. 100% decline in SAV. 

Change (observed after 14 days) in 

species composition of phytoplankton.

Phyto 

and 

Macro

 > 63 d (no recovery reported for 

shift in species composition; 

recovery in phytoplankton 

biomass and production 

occurred > 3 weeks)

From 136 day study; according to study 

authors, ponds were intensely monitored 

for first 63 days, then sampled monthly 

thereafter until day 136; however, 

exposure concentration information is not 

available past 63 days.

Y

4

deNoyelles et al., 1989; Carney, 1983 100 365 Single Mesocoms, 

experimental 

ponds

Decrease in cover by emerged and 

submerged aquatic plants (75% decline 

in Typha; 80% decline in SAV).

Macro > 1 yr (no recovery observed) From 805-d study; study concentrations 

from first year of study where ponds were 

dosed with atrazine at 100 μg/L. Y

5

deNoyelles et al., 1989; Carney, 1983 200 340 Single Mesocoms, 

experimental 

ponds

75-80% decline in Typha; >90% decline 

in SAV.

Macro > 1 yr (no recovery observed) From 805-d study; study concentrations 

from second year of study. Y

7

Hamilton et al., 1987 80 56 Multiple Lake enclosure 60% decrease in density; 20% 

decrease in number of periphyton 

species; 80% decrease in periphyton 

biomass. Change (shift observed after 

2nd day of exposure) in species 

composition.

Peri 49-50 d recovery for periphyton 

density and biomass; no 

recovery for periphyton numbers 

and shift in species composition.

Results from 1983 study cited in the 

paper. 

Y

8

Hamilton et al., 1987 140 56 Multiple Lake enclosure 60% decrease in density; 30% 

decrease in number of periphyton 

species; 75% decrease in biomass. 

Change (shift observed after 3rd day of 

exposure) in species composition.

Peri >56 d recovery for periphyton 

density and biomass; no 

recovery for periphyton numbers 

and shift in species composition.

Results from 1982 study cited in the 

paper; no significant effects in endpoints 

other than species composition observed 

although decreases were evident. Y

9

Hamilton et al., 1988 100 96 Multiple Lake enclosure Change in species composition (93% 

change in phytoplankton composition 

occurring on day 49 of study).

Phyto >323 days Duration of Hamilton studies was 323 

days after first atrazine application; 

however, measured atrazine 

concentrations were available only up to 

96 days. Exposure profile includes two 

applications of atrazine at 100 μg/L (35 

days apart).

Y

10

Herman et al., 1986; Hamilton et al., 

1989

100 96 Multiple Lake enclosure 40% decrease in POC at day 34; 80% 

decline in 14C-uptake at day 57; 10% - 

20% decrease in DO, periphyton 

biomass (50%), chlorophyll (50%), 

productivity (70%), and community 

composition (100% decrease in 

Cyanophyta).

Increase in secchi depth (30%), 

dissolved inorganic carbon (60%), and 

nitrite nitrogen (100%).

Peri 90 d; 14 d; >294 d; >294 d (POC 

recovery at 99 d; 14C-uptake 

recovery at 135 d; species comp 

recovery at >323 d).

DO, secchi depth, and dissolved 

inorganic carbon recovered by 

the next spring (329 days); no 

recovery was observed for the 

other parameters evaluated.

Duration of Hamilton studies was 323 

days after first atrazine application; 

however, measured atrazine 

concentrations were available only up to 

96 days. Exposure profile includes two 

applications of atrazine at 100 μg/L (35 

days apart). Y

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint
Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint

13

Stay et al., 1985 430 53 Single Microcosms, 

laboratory Taub 

(pickle jars)

60-70% decrease in DO; 90% decrease 

in 14C-uptake; <100% decrease in 

primary productivity (went negative); 

and 80% decrease in ratio of 14C to chla.

Phyto > 53 d (no recovery observed) Daphnid bloom occurred between days 18 

and 35 of the study and strongly 

interacted with the effects of the atrazine 

treatments. Only atrazine-related effects 

that occurred prior to the daphnid bloom 

on day 18 are considered. Full duration 

of study was 60 days with atrazine 

addition at day 7.

Y

14

Stay et al., 1985 820 53 Single Microcosms, 

laboratory Taub 

(pickle jars)

60-70% decrease in DO; 90% decrease 

in 14C-uptake; <100% decrease in 

primary productivity (went negative); 

and 80% decrease in ratio of 14C to chla.

Phyto > 53 d Daphnid bloom occurred between days 18 

and 35 of the study and strongly 

interacted with the effects of the atrazine 

treatments. Only atrazine-related effects 

that occurred prior to the daphnid bloom 

on day 18 are considered. Full duration 

of study was 60 days with atrazine 

addition at day 7.

Y

15

Stay et al., 1985 3980 53 Single Microcosms, 

laboratory Taub 

(pickle jars)

60-70% decrease in DO; 90% decrease 

in 14C-uptake; <100% decrease in 

primary productivity (went negative); 

and 80% decrease in ratio of 14C to chla.

Phyto > 53 d Daphnid bloom occurred between days 18 

and 35 of the study and strongly 

interacted with the effects of the atrazine 

treatments. Only atrazine-related effects 

that occurred prior to the daphnid bloom 

on day 18 are considered. Full duration 

of study was 60 days with atrazine 

addition at day 7.

Y

17

Brockway et al., 1984 100 7 Single Microcosms, lab 

stagnant

40% decrease in net oxygen 

production.

Phyto > 7 d Effect occurred at day 1; exposure levels 

are nominal. Y

18

Brockway et al., 1984 500 12 Single Microcosms, lab 

stagnant

90% decrease in net oxygen 

production.

Phyto >12 d Effect occurred at day 1; exposure levels 

are nominal. Y

19

Brockway et al., 1984 5000 12 Single Microcosms, lab 

stagnant

100% decrease in net oxygen 

production.

Phyto > 12 d Effect occurred at day 1; exposure levels 

are nominal. Y

22

Detenback et al., 1996 15 15 Constant Artificial flowthrough swampDecrease in DO and gross productivity 

(23% decrease in DO; reduction in 

gross productivity (p<0.05) not 

reported). Increase in nutrients (15% 

increase in PO4; 15% increase in 

ammonium).

Peri Recovery not reported. Atrazine detected in the control wetlands; 

duration of exposure is 15 days.

Y

23

Detenback et al., 1996 25 43 Constant Artificial flowthrough swampDecrease in periphyton respiration and 

net productivity (reduction in respiration 

and net primary productivity (p<0.05) 

not reported). 

Peri Recovery not reported. Atrazine detected in the control wetlands; 

duration of exposure is 43 days.

Y

24

Detenback et al., 1996 50 32 Constant Artificial flowthrough swampDecrease (reduction in net productivity 

(p <0.05)) not reported. Increase in 

nutrients (40% increase in PO4; 100% 

increase in ammonium).

Peri Recovery not reported. Atrazine detected in the control wetlands; 

duration of exposure is 32 days.

Y

25

Detenback et al., 1996 79 17 Constant Artificial flowthrough swampDecrease (reduction in net productivity 

(p <0.05)) not reported. Increase in 

nutrients (50% increase in PO4; 250% 

increase in ammonium).

Peri Recovery not reported. Atrazine detected in the control wetlands; 

duration of exposure is 17 days.

Y
Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint

26

Hamala and Kollig, 1985 100 14 Constant Microcosm, lab 

flowing

Decrease in primary production (100% 

reduction in productivity (became 

negative); 25% reduction in number of 

species; 50% reduction in biomass). 

Change in species composition (35% 

decrease in chlorophyta abundance 

observed at day 14).

Peri >14 d to > 21 d Period of exposure was 14 days with a 21 

day recovery period following exposure. 

Y

27

Johnson, 1986 1000 30 Single Microcosm, lab 

stagnant

Decrease in macrophyte biomass 

(50%); primary production (90%); 

increase in alkalinity (approx. 2-fold).

Slight decrease in pH (10%) and 

increase in conductivity (20%).

Macro >30 d Atrazine concentrations were not 

measured; nominal values were used. 

Effect occurred at day 2 (primary 

productivity) and day 30 (biomass; only 

measurement time).

Y

28

Kosinski, 1984; Kosinski and Merkle, 

1984

10 21 Single Artificial 

streams, 

recirculating 

40% decrease in apparent primary 

productivity; slight decrease in 

biovolume. 

Peri >21 d (primary production); <7 

days (biovolume)

Atrazine dissipated from the streams at a 

half-life of 3.2 days. Effect occurred at day 

7; magnitude of effect for primary 

productivity estimated using study figures. 

Results from the two publications 

(Kosinski 1984 and Kosinski and Merkle 

1984) were combined because they 

appeared to be from the same set of 

experiments.

Y

29

Kosinski, 1984; Kosinski and Merkle, 

1984

1000 21 Single Artificial 

streams, 

recirculating 

50% decrease in apparent primary 

productivity; 10% reduction in 

biovolume. 

Peri > 21 d (primary productivity); 14 

d (biovolume)

Atrazine dissipated from the streams at a 

half-life of 3.2 days. Effect occurred at day 

7; magnitude of effect for primary 

productivity estimated using study figures.

Y

30

Kosinski, 1984; Kosinski and Merkle, 

1984

10000 21 Single Artificial 

streams, 

recirculating 

70% decrease in apparent primary 

productivity; 20% to 25% reduction in 

biovolume.

Peri > 21 d Atrazine dissipated from the streams at a 

half-life of 3.2 days. Effect occurred at day 

7; magnitude of effect for primary 

productivity estimated using study figures.

Y

31

Krieger et al., 1988 24 12 Constant Artificial 

streams, 

recirculating 

Decrease in biomass (24% reduction) 

and chlorophyll-a (30% reduction). 

Slight decrease (21%, not statistically 

significant) in nitrate uptake. 

No effect on dissolved silica uptake or 

phosphorus uptake rate. 

Peri None Effect observed at last study day. 

Y

32

Krieger et al., 1988 134 12 Constant Artificial 

streams, 

recirculating 

Decrease in biomass (31% reduction), 

chlorophyll-a (44% reduction), and 

nitrate uptake (25%). 

No effect on dissolved silica uptake; 

possible slight effect (8%) on 

phosphorus uptake rate. 

Peri None Effect observed at last study day. 

Y
Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint

33

Moorhead and Kosinski, 1986 1000 7 Single Artificial 

streams, 

recirculating 

Community productivity was decreased 

by approximately 8-fold relative to 

controls.

Water quality parameters (conductivity, 

alkalinity, soluble reactive phosphorus, 

and pH), respiration, and changes in 

algal abundance were not affected.

Peri >7 d Effect on community productivity 

remained at the end of the 7 day study. 

Effect occurred at day 0.

Y

34

Pratt et al., 1988 337 21 Constant Microcosms, 

laboratory 

flowing

Statistically significant decreases in DO 

(30%), number of species (15%), 

chlorophyll-a (90%), protein biomass of 

protozoa (40%), potassium (45%), 

magnesium (20%), and calcium (15%).

Peri > 21 d Unclear what species were tested - whole 

community endpoints were evaluated. 

Colonization and diversity endpoints were 

associated with protozoa. Effect occurred 

at day 21.

Y

35

Stay et al., 1989 204 (initial 

measured)

42 Single Microcosms, 

laboratory 

Leffler

30% decrease in pH; 80% decrease in 

primary production; no effect on dark 

respiration or heterotrophic activity.

Phyto 42 - >42 d Magnitude of effect estimated from 

graphs. Y

36

Stay et al., 1989 500 42 Single Microcosms, 

laboratory 

Leffler

30% decrease in pH; 120% decrease in 

primary production; no effect on dark 

respiration or heterotrophic activity.

Phyto > 42 d Magnitude of effect estimated from 

graphs. Y

37

Stay et al., 1989 1000 42 Single Microcosms, 

laboratory 

Leffler

Decrease in pH and primary production 

(magnitude not specified); no effect on 

dark respiration or heterotrophic 

activity.

Phyto > 42 d Magnitude of effect estimated from 

graphs; values for 1000 μg/L were not 

presented but were reported to be similar 

to the 500 μg/L test concentration.

Y

38

Stay et al., 1989 5000 42 Single Microcosms, 

laboratory 

Leffler

Decrease in pH and primary production 

(magnitude not specified); no effect on 

dark respiration or heterotrophic 

activity.

Phyto > 42 d Magnitude of effect estimated from 

graphs; values for 5000 μg/L were not 

presented but were reported to be similar 

to the 500 μg/L test concentration.

Y

39

Brockway et al., 1984 50 55 Constant Microcosms, lab 

continuous flow

Approx. 30% decrease in oxygen 

production and 50% increase in 

dissolved nitrate concentration. 

Phyto >55 d Exposure was 50 μg/L (day 0 to 55) + 0 

μg/L (removal of atrazine from the system 

at day 56) + 50 μg/L (day 63 to 70); 

recovery was associated with removal of 

atrazine at day 55, and recovery occurred 

relatively rapidly. Effect occurred at day 

7; exposure levels are nominal. 

Y

40

Brockway et al., 1984 100 15 Constant Microcosms, lab 

continuous flow

Approx. 40% decrease in oxygen 

production and approx. 65% increase in 

dissolved nitrate concentration.

Phyto >15 d Exposure was complex - 100 μg/L was 

tested after exposure to 0.5 μg/L and 50 

μg/L. Treatment was as follows: 0.5 μg/L 

(days 0 to 28) + 50 μg/L (day 29) + 100 

μg/L (day 35) + 0 μg/L (removal of 

atrazine from the system at day 50) + 100 

μg/L (day 63). Effect occurred on the first 

day of treatment with 100 μg/L.

Y

41

deNoyelles et al., 1989 100 360 Single Mesocoms, 

experimental 

ponds

Decrease (>90% decline) in 14C-uptake 

and biomass of phytoplankton.

Phyto > 21 d Effect observed immediately (within first 3 

wks) in both 136-d and 805-d studies 

during the first year. Recovery observed > 

3 weeks.

Y

42

deNoyelles et al., 1989 200 360 Single Mesocoms, 

experimental 

ponds

Decrease (>90% decline) in 14C-uptake 

and biomass of phytoplankton.

Phyto > 21 d Effect observed immediately (within first 3 

wks) in both 136-d and 805-d studies 

during the first year. Recovery observed 

> 3 weeks.

Y
Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint

44

Kosinski, 1984; Kosinski and Merkle, 

1984

100 21 Single Artificial 

streams, 

recirculating 

30% decrease in apparent primary 

productivity; no affect on biovolume.

Peri < 3 d Effect occurred at day 0 and recovery 

occurred by day 3. Y

45

Moorhead and Kosinski, 1986 10000 7 Single Artificial 

streams, 

recirculating 

Community productivity was decreased 

by approximately 18-fold relative to 

controls and Nitzschia abundance was 

reduced by approx. 60%.

Water quality parameters (conductivity, 

alkalinity, soluble reactive phosphorus, 

and pH), respiration, and changes in 

non-Nitzschia algal abundance were 

not affected.

Peri >7 d Effect occurred at day 0 (day of dosing).

Y

46

Moorhead and Kosinski,1986 100 7 Single Artificial 

streams, 

recirculating 

Community productivity was decreased 

by approximately 8-fold relative to 

controls.

Water quality parameters (conductivity, 

alkalinity, soluble reactive phosphorus, 

and pH), respiration, and changes in 

algal abundance were not affected.

Peri 7 d Effect occurred at day 0.

Y

47

Stay et al., 1985 53 53 Single Microcosms, 

laboratory Taub 

(pickle jars)

40% reduction in 14C-uptake; 15-20% 

reduction in DO; 60% reduction in net 

primary productivity; and ~50% 

reduction in 14C-uptake/chl-a.

Phyto 21 - 32 d; 53 d Daphnid bloom occurred between days 18 

and 35 of the study and strongly 

interacted with the effects of the atrazine 

treatments. Only atrazine-related effects 

that occurred prior to the daphnid bloom 

on day 18 are considered. Full duration 

of study was 60 days with atrazine 

addition at day 7.

Y

48

Stay et al., 1985 84 53 Single Microcosms, 

laboratory Taub 

(pickle jars)

55% reduction in 14C-uptake; 20-30% 

reduction in DO; 55% reduction in net 

primary productivity; and ~55% 

reduction in 14C-uptake/chl-a.

Phyto 28 - 32 d; 53 d Daphnid bloom occurred between days 18 

and 35 of the study and strongly 

interacted with the effects of the atrazine 

treatments. Only atrazine-related effects 

that occurred prior to the daphnid bloom 

on day 18 are considered. Full duration 

of study was 60 days with atrazine 

addition at day 7.

Y

49

Stay et al., 1985 170 53 Single Microcosms, 

laboratory Taub 

(pickle jars)

70% reduction in 14C-uptake; 45-55% 

reduction in DO; 100% reduction in net 

primary productivity; and ~65% 

reduction in 14C-uptake/chl-a.

Phyto 28 - 32 d; 53 d Daphnid bloom occurred between days 18 

and 35 of the study and strongly 

interacted with the effects of the atrazine 

treatments. Only atrazine-related effects 

that occurred prior to the daphnid bloom 

on day 18 are considered. Full duration 

of study was 60 days with atrazine 

addition at day 7.

Y

50

Stay et al., 1989 100 42 Single Microcosms, 

laboratory 

Leffler

Decrease in pH (20%) and primary 

production (50%).

Dark respiration and heterotrophic 

activity were not affected by treatment.

Phyto 7 - >42 d Recovery did not appear to occur for the 

primary production endpoint. Effect 

occurred at day 0; magnitude of effect 

was estimated from study figures. Y

51

Brockway et al., 1984 50 12 Single Microcosms, lab 

stagnant

Approx. 25% reduction in oxygen 

production.

Phyto > 12 d Effect occurred at day 1.

Y
Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint

52

deNoyelles et al., 1982; deNoyelles et 

al., 1989

20 63 Single Mesocoms, 

experimental 

ponds

Decrease (50% decline) in 14C-uptake 

and biomass of phytoplankton. 

Phyto > 3 wks for biomass and 14Cuptake Although full exposure period was 136-d, 

atrazine exposure concentrations are 

available for only 63 days.

Y

53

Johnson, 1986 10 30 Single Microcosm, lab 

stagnant

No effect on macrophyte biomass, 

conductivity, pH, or alkalinity.

Slight (20%) decrease in gross primary 

productivity at the first measurement. 

However, this observation did not 

appear to be related to atrazine 

treatment.

Macro 7 d Exposure levels were not measured and 

atrazine was introduced as a formulated 

product associated with soil. Primary 

productivity was lower than controls from 

day 2 to 7. N

54

Johnson, 1986 100 30 Single Microcosm, lab 

stagnant

No effect on macrophyte biomass, 

conductivity, pH, or alkalinity.

Slight (30%) decrease in gross primary 

productivity. However, this observation 

did not appear to be related to atrazine 

treatment.

Macro 7 d Exposure levels were not measured and 

atrazine was introduced as a formulated 

product associated with soil. Primary 

productivity was lower than controls from 

day 2 to 7. 

N

58

Lampert et al., 1989 1 18 Single Lake enclosure 50% decrease in chlorophyll-a and 

oxygen saturation. 

Phyto >18 d Reductions in oxygen may have been 

related to daphnid mortality. However, 

chlorophyll-a reductions were considered 

to be treatment related.

Y

58b

Lampert et al., 1989 0.1 21 to 42 Single Lake enclosure Decrease in photosynthesis rate (1 of 2 

replicates in coldwater experiment only, 

60% decline) and oxygen saturation 

(approx. 40% reduction).

No clear effect on chlorophyll-a levels.

Phyto >42 d (oxygen)

>25 d (photosynthetic rate)

Endpoints evaluated include chlorophyll-a 

levels, oxygen levels, and photosynthetic 

rate. Recovery was observed for the 

photosynthetic rate in some enclosures.

Y

59

Pratt et al., 1988 32 (mean 

measured)

21 Constant Microcosms, 

laboratory 

flowing

35% decrease in DO (statistically 

significant); slight reductions in 

magnesium and calcium levels.

No effect on number of species, 

chlorophyll-a, protein biomass of 

protozoa, or potassium.

Peri > 21 d --

Y

60

Pratt et al., 1988 110 (mean 

measured)

21 Constant Microcosms, 

laboratory 

flowing

35% decrease in DO; 60% reduction in 

chlorophyll-a (not statistically 

significant); slight reductions in 

magnesium and calcium levels.

No effect on potassium, number of 

species, or protein biomass of protozoa.

Peri > 21 d --

Y

61

Stay et al., 1989 20 42 Single Microcosms, 

laboratory 

Leffler

Slight (10%) decrease in primary 

production.

No effect on pH, respiration, or 

heterotrophic activity.

Phyto 1-10 d --

N

62

van den Brink et al., 1995 5 35 Constant Microcosms, 

laboratory

Slight decrease in photosynthetic 

activity, as indicated by higher 

conductivity and alkalinity, and lower 

DO and pH.

Phyto Not applicable --

N

63

Brockway et al., 1984 0.5 7 Single Microcosms, lab 

stagnant

No effect on oxygen production. Phyto Not applicable --

N
Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint

64

Brockway et al., 1984 5 7 Single Microcosms, lab 

stagnant

No effect on oxygen production. Phyto Not applicable --

N

65

Brockway et al., 1984 0.5 29 Constant Microcosms, lab 

continuous flow

No effect on oxygen production. Phyto Not applicable 0.5 μg/L exposure occurred for 29 days, 

then exposure was increased to 50 μg/L; 

exposure levels are nominal.

N

66

Brockway et al., 1984 5 70 Constant Microcosms, lab 

continuous flow

Oxygen production was slightly reduced 

from days 10 to 45. Oxygen production 

was typically within 90% of controls, but 

was approximately 80% of controls for 

about 7 days during the first month of 

the study.

Phyto Approx. 45 d --

N

67

Gruessner and Watzin, 1996 5 14 Single with 

decreasing 

conc.

Microcosm, lab No effect on chl-a of periphyton on 

artificial substrate.

Peri Not applicable Concentration of atrazine reduced to 

1μg/L by day 14; on day 3, 15% of the 

treated water was removed and replaced 

with untreated stream water. On days 6 

and 7 about 50% of the water was 

replaced; 15% of the water was replaced 

again on day 11.

N

68 Gustavson and Wängberg, 1995 1 20 Single Lake enclosure No effect on community tolerance. Phyto 

and Peri

Not applicable -- N

69 Gustavson and Wängberg, 1995 10 20 Single Lake enclosure No effect on community tolerance. Phyto 

and Peri

Not applicable -- N

70 Gustavson and Wängberg,1995 20 20 Single Lake enclosure No effect on community tolerance. Phyto 

and Peri

Not applicable -- N

71

Jurgensen and Hoagland, 1990 2 28 2 short pulses 

of 24-hours @ 

day 1 and 14

Stream 

enclosures

No effect on cell density or biomass. Peri Not applicable Study results may have been confounded 

by a storm event and by the high 

detection limit of the analytical methods 

used in this study (50 μg/L). 

N

72

Jurgensen and Hoagland, 1990 30 28 2 short pulses 

of 24-hours @ 

day 1 and 14

Stream 

enclosures

No effect on cell density or biomass. Peri Not applicable Study results may have been confounded 

by a storm event and by the high 

detection limit of the analytical methods 

used in this study (50 μg/L). 

N

73

Jurgensen and Hoagland, 1990 100 28 2 short pulses 

of 24-hours @ 

day 1 and 14

Stream 

enclosures

No effect on cell density or biomass. Peri Not applicable Study results may have been confounded 

by a storm event and by the high 

detection limit of the analytical methods 

used in this study (50 μg/L). 

N

75

Lynch et al., 1985 25 30 (4 30-d 

exposures 

with 60-d 

intervals b/w 

exposures)

Constant/ 

Multiple (see 

comment)

Artificial 

streams, 

laboratory

No effect on standing biomass, rate of 

primary production, or community 

respiration.

Peri Not applicable DMSO was used as a solvent, and 

possible solvent effects were noted. 

Atrazine concentrations were not 

analytically confirmed. Streams were 

treated in four 30-day phases with 60 day 

recovery time between each 30 day 

exposure.

N

76

Pratt et al., 1988 3.2 (mean 

measured)

21 Constant Microcosms, 

laboratory 

flowing

No effect on DO, chlorophyll-a, protein 

biomass of protozoa, number of 

species, magnesium, calcium, or 

potassium.

Peri Not applicable --

N

77

Pratt et al., 1988 10 (mean 

measured)

21 Constant Microcosms, 

laboratory 

flowing

No effect on DO, chlorophyll-a, protein 

biomass of protozoa, number of 

species, magnesium, calcium, or 

potassium.

Peri Not applicable --

N
Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint

78

Rohr and Crumrine, 2005 25 30 Multiple Mesocosms, 

experimental 

ponds

Reduction in periphyton chlorophyll- a 

(15.2%).

Peri Recovery not reported Initial dose of atrazine was 25 μg/L, 

(nominal) then after two weeks the ponds 

were redosed with 25 μg/L (nominal). 

Thus the exposure for the first two weeks 

was 25 μg/L (nominal) and the authors 

assumed the exposure for the second two 

weeks was 50 μg/L (nominal).

Y

79

Rohr et al., 2008 117 28 Single Mesocosms, 

experimental 

ponds

Reduction in phytoplankton chlorophylla (65%) and increase in periphyton 

chlorophyll-a (49%).

Peri and 

Phyto

Recovery not reported Chlorophyll was measured only at study 

termination. Study authors attribute 

increase in periphyton chlorophyll-a to 

reduction in phytoplankton, which 

facilitates increased nutrient availability 

and light penetration to periphyton.

Y

80

Relyea, 2009 6.4 36 Single Outdoor 

mesocosms, 

experimental 

ponds

No effect to phytoplankton chlorophylla, periphyton biomass, and dissolved 

oxygen.

Peri and 

Phyto

Not applicable Solvent concentration reported for control 

only.

N

81

Knauert et al., 2008; Knauert et al., 

2009

84 173 Multiple Outdoor 

mesocosms, 

experimental 

ponds

Inhibition of phytoplankton 

photosynthetic activity (51.4%) at day 2. 

Average inhibition of photosynthetic 

activity from day 0-34 was 45.6%. 

Change in phytoplankton community 

structure.

Phyto No recovery (compared to 

control ponds, atrazine resulted 

in statistically significant effects 

on photosynthesis and 

differences in phytoplankton 

species composition until the 

end of the experiment at day 

173).

Study duration included 34 days of 

constant atrazine exposure followed by a 

post-exposure period of approximately 5 

months (139 days) where atrazine 

dissipated in the water column. The total 

duration of the study was 173 days. In 

order to maintain constant atrazine 

concentrations, atrazine was reapplied to 

the ponds only once on day 20. Atrazine 

caused a statistically significant reduction 

in photosynthetic activity of phytoplankton 

at day 2 of the study. Changes in 

phytoplankton community structure began 

at day 12.

Y

82

Berard et al., 1999a, Berard et al., 

1999b, Berard and Benninghoff, 2001, 

Sequin et al., 2001b, Leboulanger et 

al., 2001

10 10 to 23 Single Experimental 

outdoor 

microcosms

Change in phytoplankton biomass and 

community structure (species and 

higher taxonomic groupings 

composition, species diversity 

(Shannon index), and Bray-Curtis 

index).

Phyto Recovery not reported Reported atrazine concentration in source 

lake is relatively low compared to 

treatment concentration, although 

background measurements were not 

taken during the experiment and may 

have been higher. Study authors indicate 

that experiments were conducted for 10-

23 days (just before the stationary phase 

of phytoplankton growth). Endpoints were 

measured at the end of the experiments; 

the type and magnitude of effects varied 

among the experiments and effects were 

observed across the range of 

experimental durations.

Y

83

Seguin et al., 2001a 30 40 Single Outdoor 

mesocosms, 

experimental 

ponds

Increase (61%) in periphyton 

chlorophyll-a concentration at Day 40.

Peri Recovery not reported Increased chlorophyll observed only at 

study termination. Also examined effects 

of nicosulfuran in separate treatments. N

84

Seguin et al., 2001a 2 40 Single Outdoor 

mesocosms, 

experimental 

ponds

No effect Peri Not applicable Non-significant increase (14%) in 

periphyton chlorophyll-a concentration at 

day 40. Also examined effects of 

nicosulfuran in separate treatments. 

N
Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint

85

Seguin et al., 2001b 30 40 Single Experimental 

outdoor 

mesocosms

Change in phytoplankton community 

structure (change in Bray-Curtis index 

starting on day 2 and increased 

Chrysophyceae abundance of unknown 

magnitude on day 40).

Phyto Recovery not reported Also examined effects of nicosulfuran in 

separate treatments. 

Y

86

Seguin et al., 2001b 2 40 Single Experimental 

outdoor 

mesocosms

Increased Chrysophyceae abundance 

on day 40 (unknown magnitude).

Phyto Recovery not reported Effect on abundance observed at study 

termination. Also examined effects of 

nicosulfuran in separate treatments. Y

87

Seguin et al., 2002 30 25 Single Experimental 

outdoor 

mesocosms

Decrease in chlorophyll-a (22%) and 

dry weight (30%); change in community 

structure and Bray-Curtis similarity 

index; decrease in DO (20%).

Phyto No Changes in biomass (chlorophyll-a and 

dry weight) were evident at day 9, 

changes in community structure began at 

day 11, changes in Bray-Curtis began day 

9, and changes in DO about day 3. 

Although DO showed an apparent 

recovery about day 12, it diverged from 

the control again starting about day 17 

through the end of the experiment. Shortterm toxicity data from the atrazinetreated mesocosm communities was not 

considered for the data summary table 

due to the uncertainty surrounding 

exposure concentrations.

Y

88

Downing et al., 2004 148 7 Single Laboratory 

microcosms

Decrease in chlorophyll-a (30-40%), 

primary productivity (~60%), and 

change in phytoplankton composition 

(~20% decrease in diatoms, ~25% 

decrease in bluegreen algae, ~30% 

decrease in green algae, ~75% 

decrease in brown algae, ~30% 

decrease in total phytoplankton). 

Phyto Recovery not reported Initial test concentrations are based on 

the average of reported measured day 0 

values from the October 1999 and 

February 2000 experiments (112 - 184 

μg/L); the corresponding nominal test 

concentration is 200 μg/L. Chlorothalnil 

and endosulfan were also investigated 

separately.

Y

89

Downing et al., 2004 24.3 7 Single Laboratory 

microcosms

Decrease in chlorophyll-a (~35%) and 

change in phytoplankton composition 

(~15% decrease in diatoms, ~5% 

decrease in green algae, ~25% 

decrease in brown algae, ~10% 

decrease in total phytoplankton). 

Phyto Recovery not reported Initial test concentrations are based on 

the average of reported measured day 0 

values from the October 1999 and 

February 2000 experiments (23.8 - 24.8 

μg/L) ); the corresponding nominal 

concentration is 20 μg/L. Chlorothalnil 

and endosulfan were also investigated 

separately.

Y

90

Boone and James, 2003 207 25 Single Outdoor 

mesocosms, 

experimental 

ponds

No clear treatment-related effects. Phyto Not applicable Main purpose of the study was to evaluate 

effects of atrazine and carbaryl on 

amphibians. Chlorophyll content was 

measured as a potential indirect effect 

(effect on food availability) to amphibians. 

Control levels were higher than all 

treatment levels (regardless of whether or 

not atrazine was present) at day 12 in 

Experiment 1. However, there were no 

apparent decreases in chlorophyll in any 

treatment with atrazine and chlorophyll in 

the atrazine-only treatment was higher 

than the control on day 25.

N
Endpoint 

Number

Reference(s) Initial Test 

Concentra

tion (μg/L)

Duration 

(d)

Single / 

Constant / 

Multiple

Ecosystem Results Plant 

Group

Recovery Comments Effect 

(Y/N)

Cosm Endpoint Table Taken from August 2011 Memo, Organized by Number of Endpoint

95

Diana et al., 2000 20 51 Single Outdoor 

microcosms

No clear treatment-related effects. Macro 

and 

Phyto

Not applicable Atrazine concentrations were only 

determined at 0 and 21 days posttreatment. Chlorophyll was measured 

through day 42 and macrophytes biomass 

was measured at the end of the 

experiment (day 51).

N

96

Diana et al., 2000 196 51 Single Outdoor 

microcosms

98% decrease in macrophyte biomass; 

3-fold increase in phytoplankton 

chlorophyll-a on day 14; approximate 

60% reduction in pre-dusk DO levels at 

day 1. 

Macro 

and 

Phyto

No – chlorophyll-a increase was 

observed from day 14 to study 

termination; DO did not recover, 

and biomass was only measured 

at study termination.

Atrazine concentrations were only 

determined at 0 and 21 days posttreatment. Chlorophyll was measured 

through day 42 and macrophytes biomass 

was measured at the end of the 

experiment (day 51).

Y

97

Diana et al., 2000 2036 51 Single Outdoor 

microcosms

99% decrease in macrophyte biomass; 

2-fold increase in phytoplankton 

chlorophyll-a; approximate 80% 

reduction in pre-dusk DO levels at day 

1.

Macro 

and 

Phyto

No - biomass was only measured 

at study termination, and DO 

levels did not recover. However, 

chlorophyll concentrations were 

similar to control by day 42. 

Atrazine concentrations were only 

determined at 0 and 21 days posttreatment. Chlorophyll was measured 

through day 42 and macrophytes biomass 

was measured at the end of the 

experiment (day 51). 

Y

98

McGregor et al., 2008 25 42 Single Outdoor 

microcosms

No effect on dissolved oxygen. Macro 

and 

Phyto

Not applicable DO was measured through day 40. Study 

focused on macrophytes, however DO 

measurements would have included 

effects on phytoplankton present in the 

microcosms. Effects on macrophyte 

biomass were also reported in the study; 

however, no effect levels were reported 

for biomass effects. 

N

99

McGregor et al., 2008 50 42 Single Outdoor 

microcosms

No effect on dissolved oxygen. Macro 

and 

Phyto

Not applicable DO was measured through day 40. Study 

focused on macrophytes, however DO 

measurements would have included 

effects on phytoplankton present in the 

microcosms. Effects on macrophyte 

biomass were also reported in the study; 

however, no effect levels were reported 

for biomass effects. 

N

100

McGregor et al., 2008 100 42 Single Outdoor 

microcosms

35% decrease in DO at day 1. Macro 

and 

Phyto

No DO was measured through day 40. Study 

focused on macrophytes, however DO 

measurements would have included 

effects on phytoplankton present in the 

microcosms. Effects on macrophyte 

biomass were also reported in the study; 

however, no effect levels were reported 

for biomass effects. 

Y

101

McGregor et al., 2008 250 42 Single Outdoor 

microcosms

50% decrease in DO at day 1. Macro 

and 

Phyto

No DO was measured through day 40. Study 

focused on macrophytes, however DO 

measurements would have included 

effects on phytoplankton present in the 

microcosms. Effects on macrophyte 

biomass were also reported in the study; 

however, no effect levels were reported 

for biomass effects. 

Y

*Duration corresponds to the number of days for which atrazine exposure concentrations are available. Study durations that are longer than the period of time for which atrazine concentrations are available are specified in the "Comments" column.