Technique of Measuring Phytoplankton Primary Production
35
internal parts should be made of neutral plastic materials, and its central metal
core coated with a plastic lining. For some kinds of water bodies, including
lagoons and shallow areas of the sea, plastic water bottles of Niskin or Van
Dorn types can be used for sampling from small boats. Among all types of
water bottle known to me, the best for this purpose (and also for work in the
deep sea) is the Suslyaev plastic water bottle, which was constructed in the
workshop of Shirshov's Oceanology Institute of the Russian Academy of
Sciences.
When preparing the water bottle for use, it should be kept filled with water
for 1-2 days (new ones for 1-2 weeks). Then its internal surface should be
washed with detergent and carefully rinsed with hot water. During sampling,
the internal surfaces of the water bottle should be periodically cleaned with
the aid of a sponge moistened with ethanol to prevent microbial overgrowth
and to clean them of grease. All these precautions are needed to decrease
contamination of samples by strange heterotrophic microflora. The latter
enhances the bottle effects and dark 14COZ uptake, thus influencing the precision of primary production measurements.
As has been mentioned above, the cells of phytoplankton and their assemblages are very sensitive to mechanical disturbance and to contract with solid
surfaces. Therefore, the sample arriving aboard in the water bottle should be
discharged into the experimental bottles very gently. This condition is especially important when working on the open sea, where very fragile colonial
and coenobial forms of diatoms predominate, which are especially adapted to
the water column, like Chaetoceros, Rhizosolenia, Nitzschia, Thalssiosira.
The samples must therefore be discharged at a difference in levels of not more
than 20cm through a silicon rubber tube not less than 8mm in diameter, going
straight from the lid of the water bottle without any intermediate tap or impediment. The flow can be regulated by the upper tap. Sampling from large water
bottles, which can be quite tall, can be done by a glass syphon through the
upper lid. I used to take subsampJes for primary production measurements
from 100-1 water bottles, opening the upper valve completely, and taking the
sample with the aid of a glass beaker with a handle. For sampling from the
surface layer of the water body, a clean polyethylene bucket can also be used.
The water thus sampled should be instantly poured into the glass jar or beaker,
and then distributed into the experimental bottles with a funnel with a wide
(8-mm) end tube which extends down close to the bottom of the bottles to
decrease mechanical disturbance of the phytoplankton.
2.3.2.5 Experiments to Measure the Absolute Photosynthesis Rate (Cp ) and
Primary Production (Cps) in the Surface Water Layer
To measure the absolute rate of phytoplankton photosynthesis in a sample
of water (Cp , mg C m- 3 h- I ), the sample is distributed into three experimental
bottles prepared as described above (Sect. 3.2.3). The bottles should be filled
35
internal parts should be made of neutral plastic materials, and its central metal
core coated with a plastic lining. For some kinds of water bodies, including
lagoons and shallow areas of the sea, plastic water bottles of Niskin or Van
Dorn types can be used for sampling from small boats. Among all types of
water bottle known to me, the best for this purpose (and also for work in the
deep sea) is the Suslyaev plastic water bottle, which was constructed in the
workshop of Shirshov's Oceanology Institute of the Russian Academy of
Sciences.
When preparing the water bottle for use, it should be kept filled with water
for 1-2 days (new ones for 1-2 weeks). Then its internal surface should be
washed with detergent and carefully rinsed with hot water. During sampling,
the internal surfaces of the water bottle should be periodically cleaned with
the aid of a sponge moistened with ethanol to prevent microbial overgrowth
and to clean them of grease. All these precautions are needed to decrease
contamination of samples by strange heterotrophic microflora. The latter
enhances the bottle effects and dark 14COZ uptake, thus influencing the precision of primary production measurements.
As has been mentioned above, the cells of phytoplankton and their assemblages are very sensitive to mechanical disturbance and to contract with solid
surfaces. Therefore, the sample arriving aboard in the water bottle should be
discharged into the experimental bottles very gently. This condition is especially important when working on the open sea, where very fragile colonial
and coenobial forms of diatoms predominate, which are especially adapted to
the water column, like Chaetoceros, Rhizosolenia, Nitzschia, Thalssiosira.
The samples must therefore be discharged at a difference in levels of not more
than 20cm through a silicon rubber tube not less than 8mm in diameter, going
straight from the lid of the water bottle without any intermediate tap or impediment. The flow can be regulated by the upper tap. Sampling from large water
bottles, which can be quite tall, can be done by a glass syphon through the
upper lid. I used to take subsampJes for primary production measurements
from 100-1 water bottles, opening the upper valve completely, and taking the
sample with the aid of a glass beaker with a handle. For sampling from the
surface layer of the water body, a clean polyethylene bucket can also be used.
The water thus sampled should be instantly poured into the glass jar or beaker,
and then distributed into the experimental bottles with a funnel with a wide
(8-mm) end tube which extends down close to the bottom of the bottles to
decrease mechanical disturbance of the phytoplankton.
2.3.2.5 Experiments to Measure the Absolute Photosynthesis Rate (Cp ) and
Primary Production (Cps) in the Surface Water Layer
To measure the absolute rate of phytoplankton photosynthesis in a sample
of water (Cp , mg C m- 3 h- I ), the sample is distributed into three experimental
bottles prepared as described above (Sect. 3.2.3). The bottles should be filled