Bacterio Plankton
91
survivals after the Utremol procedure. For example, in a lagoon of the
barrier reef off Tahiti I, they comprised only 10-30% of the total primary
production. The larger part of it was composed by nanoplanktonic algaeflagellates and coccoliths (Ricard 1977b).
Fundamental studies of phytoplankton in reef waters off some islands of
French Polynesia were accomplished by Ricard (1976, 1977b). He described
580 species of algae in them, which belonged to 70 genera. The most
common of them, which were found in samples all around the year, were
Actinocyclus ehrenbergii, A. subtilis, Ethmodiscus appendiculatus,
Gyrosigma balticum, Melosira sulcata, Navicula longilyra, Nitzschia seriata,
N. longissima, and Surirella fastuosa. During the seasons the phytoplankton
communities were periodically dominated by some common Chaetoceros
species: Ch. curvisetus, Ch. atlanticum, Ch. compressum, and by some other
diatoms, like Synedra acus, Amphora lineolata, A. angulata, Coscinodiscus
moelleri, Surirella gemma, and Asterionella notata. In lagoonal
phytoplankton during some seasonal periods the blue green algae Lyngbia,
Nostoc and Oscillatoria were numerous.
In the phytoplankton samples collected by French researchers in lagoons
of some atolls of the Society and the Tuamotu Islands often the
dinoflagellates Goniaulax, Ceratium, Peridinium were more numerous than
the diatoms (Sournia and Ricard 1975a,b, 1976a). Dense populations of
them were recorded in the lagoon of the Takapoto atoll. The
cocolithophorids and blue-green algae were also numerous. Total numbers
of planktonic algae, recorded in the lagoonal waters were high even with the
use of Utremol sedimentation: 10 4 -10 6 cells 1-1, to say nothing of the
possible loss of a larger part of them during 8 months storage of the Utremol
samples before their processing in Paris. The same authors pointed out a
high percentage of ben tho-planktonic diatoms in the samples. But this
statement, which could be found also in earlier publications (Marshall 1933;
Jeffrey 1968), may be as well an artifact, caused by better resistance of these
algae to fixatives and to storage. If the delicate cells of other algae had been
ruined during this procedure, the ratio was artificially moved to the firm
ben tho-planktonic diatoms.
The seasonal observations revealed a real "bloom" of phytoplankton in
lagoons of atolls, such as Takapoto, Rangiroa, Moruroa and Rongelap
(Johnson 1954; Michel et al. 1972). So even by employing insufficient
sedimentation methodology, leading to a large loss of phytoplankton cells,
the above research demonstrated that in waters of the lagoons of spme atolls
a varied and abundant phytoplankton exists. Large seasonal variations in its
number and composition finally disproved former ideas about the
homeostasis in plankton communities of tropical seas.
Observations on phytoplankton in the lagoon of the Great Barrier Reef
revealed its seasonal maxima to be in Spring and in Autumn (Relevante and
Gilmartin 1982). The first was dominated by the diatoms Chaetoceros
compressus, Bacteriastrum comosum and Nitzschia pungens. During the
91
survivals after the Utremol procedure. For example, in a lagoon of the
barrier reef off Tahiti I, they comprised only 10-30% of the total primary
production. The larger part of it was composed by nanoplanktonic algaeflagellates and coccoliths (Ricard 1977b).
Fundamental studies of phytoplankton in reef waters off some islands of
French Polynesia were accomplished by Ricard (1976, 1977b). He described
580 species of algae in them, which belonged to 70 genera. The most
common of them, which were found in samples all around the year, were
Actinocyclus ehrenbergii, A. subtilis, Ethmodiscus appendiculatus,
Gyrosigma balticum, Melosira sulcata, Navicula longilyra, Nitzschia seriata,
N. longissima, and Surirella fastuosa. During the seasons the phytoplankton
communities were periodically dominated by some common Chaetoceros
species: Ch. curvisetus, Ch. atlanticum, Ch. compressum, and by some other
diatoms, like Synedra acus, Amphora lineolata, A. angulata, Coscinodiscus
moelleri, Surirella gemma, and Asterionella notata. In lagoonal
phytoplankton during some seasonal periods the blue green algae Lyngbia,
Nostoc and Oscillatoria were numerous.
In the phytoplankton samples collected by French researchers in lagoons
of some atolls of the Society and the Tuamotu Islands often the
dinoflagellates Goniaulax, Ceratium, Peridinium were more numerous than
the diatoms (Sournia and Ricard 1975a,b, 1976a). Dense populations of
them were recorded in the lagoon of the Takapoto atoll. The
cocolithophorids and blue-green algae were also numerous. Total numbers
of planktonic algae, recorded in the lagoonal waters were high even with the
use of Utremol sedimentation: 10 4 -10 6 cells 1-1, to say nothing of the
possible loss of a larger part of them during 8 months storage of the Utremol
samples before their processing in Paris. The same authors pointed out a
high percentage of ben tho-planktonic diatoms in the samples. But this
statement, which could be found also in earlier publications (Marshall 1933;
Jeffrey 1968), may be as well an artifact, caused by better resistance of these
algae to fixatives and to storage. If the delicate cells of other algae had been
ruined during this procedure, the ratio was artificially moved to the firm
ben tho-planktonic diatoms.
The seasonal observations revealed a real "bloom" of phytoplankton in
lagoons of atolls, such as Takapoto, Rangiroa, Moruroa and Rongelap
(Johnson 1954; Michel et al. 1972). So even by employing insufficient
sedimentation methodology, leading to a large loss of phytoplankton cells,
the above research demonstrated that in waters of the lagoons of spme atolls
a varied and abundant phytoplankton exists. Large seasonal variations in its
number and composition finally disproved former ideas about the
homeostasis in plankton communities of tropical seas.
Observations on phytoplankton in the lagoon of the Great Barrier Reef
revealed its seasonal maxima to be in Spring and in Autumn (Relevante and
Gilmartin 1982). The first was dominated by the diatoms Chaetoceros
compressus, Bacteriastrum comosum and Nitzschia pungens. During the