Eutrophication Control of Tsalmon Reservoir
221
Table 2. Quality and quantity of foods in 1 kg. of Tilapia aurea
and chemical quality of sediments on bottom of Tsalmon reservoir in 1971.
Date
20.1
17.3
20.4
24.5
28.6
19.7
12.8
Wet wt.
g·
41.3
59.6
44.0
48.8
53.4
30.4
36.8
In fish intestines
Dry wt.
g·
9.95
13.7
8.6
8.7
12.1
6.4
10.3
Organic
matter %
31.79
34.5
47.4
63.4
42.3
41.2
36.8
Carbon
%
21.3
23.1
31.8
42.8
28.3
27.6
24.7
Nitrogen
%
2.19
2.58
2.97
2.66
1.7
3.03
Carbon
to
nitrogen
ratio
10
9
11
16
17
9
1
1
1
1
1
1
On reservoir
bottom
Organic
matter
%
12.4
12.4
12.1
12.9
12.0
11.2
10.6
Nitrogen
%
0.70
0.96
0.74
0.77
0.80
0.75
Tilapia aurea fish and Peridinium cinctum alga
Peridinium alga is the dominant one in the water in the period of February to June
(see Fig. 4) and contributes a large portion of the organic matter on the reservoir bottom.
During this period its concentration in the water reaches 50,000 to 150,000 cells per litre.
In the intestinal tract of fish weighing between 100 and 800 g. each gram of wet food
contained between 4.7 and 7.2 million cells of Peridinium.
The fish are able to take the algae from the water or from the reservoir bottom after
they have sunk, the number depending on the algae concentration in the water. An
experiment in which some fish were kept in the reservoir bottom showed no appreciable
difference in the number of algae per gram of wet material with that in fish caught near
the cages. A difference was found in the total amount of food in the intestinal tract
which was 15% higher in the fish caught in the reservoir.
Table 3. Number of Peridinium cinctum cells and chemical composition
of food in Tilapia aurea fish in the Tsalmon Reservoir on April 20, 1971.
Weight
of fish
g100
300
500
600
700
800
Number
of Peridinium
cells
perg.
68.10
5
47.10
5
27.10
s
48.10
s
52.10
s
64.10
s
Wet
material
g9
17
16
31
24
35
Dry
material
g·
2.50
3.70
3.43
6.67
4.49
5.10
Organic
Material
%
43.3
50.0
46.9
50.6
44.9
48.7
Carbon
%
29.1
33.5
31.4
33.9
30.1
32.6
Nitrogen
%
3.03
3.16
3.05
2.92
2.99
2.65
Carbon
to Nitrogen
ratio
9 : 1
10: 1
10: 1
11 : 1
10: 1
12: 1
221
Table 2. Quality and quantity of foods in 1 kg. of Tilapia aurea
and chemical quality of sediments on bottom of Tsalmon reservoir in 1971.
Date
20.1
17.3
20.4
24.5
28.6
19.7
12.8
Wet wt.
g·
41.3
59.6
44.0
48.8
53.4
30.4
36.8
In fish intestines
Dry wt.
g·
9.95
13.7
8.6
8.7
12.1
6.4
10.3
Organic
matter %
31.79
34.5
47.4
63.4
42.3
41.2
36.8
Carbon
%
21.3
23.1
31.8
42.8
28.3
27.6
24.7
Nitrogen
%
2.19
2.58
2.97
2.66
1.7
3.03
Carbon
to
nitrogen
ratio
10
9
11
16
17
9
1
1
1
1
1
1
On reservoir
bottom
Organic
matter
%
12.4
12.4
12.1
12.9
12.0
11.2
10.6
Nitrogen
%
0.70
0.96
0.74
0.77
0.80
0.75
Tilapia aurea fish and Peridinium cinctum alga
Peridinium alga is the dominant one in the water in the period of February to June
(see Fig. 4) and contributes a large portion of the organic matter on the reservoir bottom.
During this period its concentration in the water reaches 50,000 to 150,000 cells per litre.
In the intestinal tract of fish weighing between 100 and 800 g. each gram of wet food
contained between 4.7 and 7.2 million cells of Peridinium.
The fish are able to take the algae from the water or from the reservoir bottom after
they have sunk, the number depending on the algae concentration in the water. An
experiment in which some fish were kept in the reservoir bottom showed no appreciable
difference in the number of algae per gram of wet material with that in fish caught near
the cages. A difference was found in the total amount of food in the intestinal tract
which was 15% higher in the fish caught in the reservoir.
Table 3. Number of Peridinium cinctum cells and chemical composition
of food in Tilapia aurea fish in the Tsalmon Reservoir on April 20, 1971.
Weight
of fish
g100
300
500
600
700
800
Number
of Peridinium
cells
perg.
68.10
5
47.10
5
27.10
s
48.10
s
52.10
s
64.10
s
Wet
material
g9
17
16
31
24
35
Dry
material
g·
2.50
3.70
3.43
6.67
4.49
5.10
Organic
Material
%
43.3
50.0
46.9
50.6
44.9
48.7
Carbon
%
29.1
33.5
31.4
33.9
30.1
32.6
Nitrogen
%
3.03
3.16
3.05
2.92
2.99
2.65
Carbon
to Nitrogen
ratio
9 : 1
10: 1
10: 1
11 : 1
10: 1
12: 1