International Journal of Marine Science 2016, Vol.6, No.01, 1-8
5
the nutrient salts of the filtered seawater that used in the
culture F/2 media in the present study.
Photosynthetic pigments
Chlorophylls are key compounds in plants for trapping
light energy for photosynthesis, thus their quantitative
determination is of great importance in the studies of
photosynthesis, primary production and related subjects.
Chlorophyll-a, c hlorophyll-c and the accessory
photosynthetic pigment Carotenoids were measured in
this study.
The results in Fig. 4, 5, 6, 7, 8 and 9 indicated that, chl-a,
chl-c and carotenoids content of
Chaetoceros simplex
followed a similar pattern of change to that of growth in
response to different treatments of nitrate and phosphate.
The addition of 100 μMnitrate and 5 μMphosphate to the
culture medium recorded amaximum Chl-a of 0.72±0.02
μg·ml
-1
and 0.69±0.05 μg·ml
-1
, respectively as compared
with the control culture. While, the concentrations of 300
μM nitrate and 50 μM phosphate sustained the lowest
chlorophyll- a of 0.35±0. 02 μg·ml
-1
and 0.36±0. 02
μg·ml
-1
, respectively. This result is in accordance with
that obtained by De la Curz et al. (2006) who reported
that chlorophyll–
a
content was directly related to cellular
density and indirectly to concentration of nutrients. In the
present study, the chlorophyll-
a
content sustained its
highest value at the early exponential growth phase,
which coincided with the data reported by Hemalatha et
al. (2014). The chl-c and carotenoid contents showed an
increasing trend up to 100 μM nitrate and 5 μM
phosphates. The addition of 100 μM nitrate to the culture
medium rec orded a maximum c hlorophyll-c of
0.52±0.02 μg·ml
-1
and carotenoids value of 4.1±0.03
μg·ml
-1
, while additions of 5 μM phosphate sustained
chl-c of 0.49±0.03 μg·ml
-1
and carotenoids of 3.4±0.02
μg·ml
-1
).
Total soluble proteins
The total soluble proteins of
Chaetoceros simplex
in
the present study were increased in the culture treated
with 100 μM nitrate and 5 μM phosphates by about 37
and 32 %, respectively over the control culture after
eight days of incubation. On the other hand, the
concentrations of 300 μM nitrate and 50 μM
phosphate inhibited the total soluble proteins of the
tested organism by about 33 and 38%, respectively,
below the control culture (Tables 3 and 4). Hemalatha
Fig 4 Effect of different concentrations of nitrate (μM) on the
chlorophyll-a (μg·ml
-1
) of
Chaetoceros simplex
(Each value is
the mean ±SD)
Fig 5 Effect of different concentrations of phosphate (μM) on the
chlorophyll-a (μg·ml
-1
) of
Chaetoceros simplex
(Each value is the
mean ±SD)
Fig 6 Effect of different concentrations of nitrate (μM) on the
chlorophyll-c (μg·ml
-1
) of
Chaetoceros simple
(Each value is
the mean ±SD)
Nitrate
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0
2
5
8
10
12
Days
chlorophyll-a (μg.ml
-1
)
Control
1 μM
5 μM 50 μM 100 μM 200 μM
300 μM
Nitrate
0
0.1
0.2
0.3
0.4
0.5
0.6
0
2
5
8
10
12
Days
Chlorophyll-c (μg.ml
-1
)
Control
1 μM
5 μM 50 μM 100 μM 200 μM
300 μM
Phosphate
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0
2
5
8
10
12
Days
chlorophyll-a (μg.ml
-1
)
Control
0.3 μM 1 μM 5 μM 25 μM 50 μM
