the influence on the ecosystem was reduced because the interaction among the
organisms in the microcosm functioned where one ecosystem is constructed.
From these outcomes, it was estimated that the m-NOEC of the structural
parameter was greater than 5 mg/L because, while mainly the zooplankton were
affected, extinction was not observed. Similarly, the m-NOEC of the functional
parameter was also estimated as being greater than 5 mg/L, and there was an
observed tendency toward increased production and respiration in all addition
systems. Populations of phytoplankton and zooplankton decreased with the increasing addition concentration of propyzamide, but the activity per individual rose
simultaneously, and it was thought that equilibrium was maintained. Influence on
ecosystem was relaxed than a single creature by the microbial interaction in microcosm, and it was made clear that a difference was observed in comparison with the
effects of Propyzamide in the single-species test.
7.3.6 2-Methyl-4-Chlorophenoxyacetic Acid (MCPA)
2-Methyl-4-chlorophenoxyacetic acid (MCPA), a chemical substance similar to
auxin, disturbs hormonal balance and is therefore a hormonal drug. The addition
concentration of MCPA was adjusted to 0.1, 0.2, 0.3, 0.4, and 0.5 mg/L, and it was
added on the 16th day of the stable state into the microcosm. The endpoints were
population density (structural parameter) and the concentration of DO (functional
parameter), and the population was measured using an optical microscope and
counted from the start of culturing on days 0, 2, 4, 7, 14, 16, 18, 20, 23, and
30, and it was evaluated from the results of B 16–30 (days 16–30), which was the
ratio of abundance and population density (N 30 ) on the 30th day. The DO concentration was measured continuously from the 16th day, and the P/R ratio was
calculated from the amounts of production (P) and respiration (R).
Extinction of the constituent microorganism was not confirmed from the evaluation of the population density, nor was ecological collapse observed in the
a) acetone
b) 1mg/L addition
c) 3mg/L addition
d) 5mg/L addition
Production(mg O
2 /L)
Production(mg O
2 /L)
Production(mg O
2 /L)
Production(mg O
2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
0
2
4
6
8
10
0
2
4
6
8
10
0
2
4
6
8
10
0
2
4
6
8
10
0 2 4 6 8 10
0 2 4 6 8 10
0 2 4 6 8 10
0 2 4 6 8 10
Fig. 7.12 Time course of P/R ratio in Propyzamide-added microcosm N-system. (a) Acetone. (b)
1 mg/L addition. (c) 3 mg/L addition. (d) 5 mg/L addition
90
K. Murakami et al.
organisms in the microcosm functioned where one ecosystem is constructed.
From these outcomes, it was estimated that the m-NOEC of the structural
parameter was greater than 5 mg/L because, while mainly the zooplankton were
affected, extinction was not observed. Similarly, the m-NOEC of the functional
parameter was also estimated as being greater than 5 mg/L, and there was an
observed tendency toward increased production and respiration in all addition
systems. Populations of phytoplankton and zooplankton decreased with the increasing addition concentration of propyzamide, but the activity per individual rose
simultaneously, and it was thought that equilibrium was maintained. Influence on
ecosystem was relaxed than a single creature by the microbial interaction in microcosm, and it was made clear that a difference was observed in comparison with the
effects of Propyzamide in the single-species test.
7.3.6 2-Methyl-4-Chlorophenoxyacetic Acid (MCPA)
2-Methyl-4-chlorophenoxyacetic acid (MCPA), a chemical substance similar to
auxin, disturbs hormonal balance and is therefore a hormonal drug. The addition
concentration of MCPA was adjusted to 0.1, 0.2, 0.3, 0.4, and 0.5 mg/L, and it was
added on the 16th day of the stable state into the microcosm. The endpoints were
population density (structural parameter) and the concentration of DO (functional
parameter), and the population was measured using an optical microscope and
counted from the start of culturing on days 0, 2, 4, 7, 14, 16, 18, 20, 23, and
30, and it was evaluated from the results of B 16–30 (days 16–30), which was the
ratio of abundance and population density (N 30 ) on the 30th day. The DO concentration was measured continuously from the 16th day, and the P/R ratio was
calculated from the amounts of production (P) and respiration (R).
Extinction of the constituent microorganism was not confirmed from the evaluation of the population density, nor was ecological collapse observed in the
a) acetone
b) 1mg/L addition
c) 3mg/L addition
d) 5mg/L addition
Production(mg O
2 /L)
Production(mg O
2 /L)
Production(mg O
2 /L)
Production(mg O
2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
0
2
4
6
8
10
0
2
4
6
8
10
0
2
4
6
8
10
0
2
4
6
8
10
0 2 4 6 8 10
0 2 4 6 8 10
0 2 4 6 8 10
0 2 4 6 8 10
Fig. 7.12 Time course of P/R ratio in Propyzamide-added microcosm N-system. (a) Acetone. (b)
1 mg/L addition. (c) 3 mg/L addition. (d) 5 mg/L addition
90
K. Murakami et al.