226
B. KIMOR:
Finally, FROt-.'TIER (1963 a) measuring the quantitative distribution of zooplankton
by mm 3 per I m of advancing net, points to the NE part of the Arabian Sea as one of the
richest with values reaching up to 982 mm 3 , while in the main basin of the Arabian Sea
the values fluctuate between 25 - 65 mm 3 • Abrupt differences in zooplankton biomass
have been established by the same investigator in different areas of the Persian and Aden
Gulf, depending on whether the stations are coastal or more offshore and other factors.
The evidence emerging from these sources, despite the different parameters used,
indicates a higher level of plankton productivity in the NW part of the Arabian Sea,
more especially in the coastal areas, than in the Red Sea in general and its northern parts
in particular.
III. Phytoplankton
From a qualitative standpoint the 3 regions under discussion belong, according to
SUKHANOVA (1962 b), to the "Basic Indo-oceanic complex" whereby several species of
dinoflagellates common to the whole of the tropical areas of the Indian Ocean constitute
an outstanding feature of the phytoplankton. These species are Pyrocystis pseudonoctiluca, Ceratium carriense, C. trichoceros and C. massiliense.
In a more recent work SUKHANOVA (1969) established important differences in the
diversity of species in the different parts of the Red Sea and the Gulf of Aden. Accordingly
the central part of the Red Sea is the poorest in species with more diverse populations in
the northern and southern parts.
The dinoflagellates in general seem to be more uniformly distributed in the whole
region while the diatoms exhibit a more discontinuous distribution and very rarely
produce the water blooms characteristic of other areas of the Indian Ocean (SUBRAHMANYAN, 1960). Among such cases SUKHANOVA cites Climacodium frauenfeldianum
as reaching higher numbers in the Gulf of Aden, while in the Gulf of Eilat a one-time
occurrence of a waterbloom caused by Stephanopyxis palmeriana was noted by the
author (KIMOR, 1970) in February 1958.
SUKHANOVA's findings (1969) that many species recorded from the Arabian Sea and
other parts of the Indian Ocean (SUBRAHMANYAN, 1958) are not found in the Red Sea,
are amply corroborated by WOOD (1963). Out of a total of 452 species of his checklist
of dinoflagellates recorded from the Indian Ocean, only 170 are represented in the areas
under discussion. Of the 47 genera comprising WOOD's checklist of species for the Indian
Ocean as a whole, 14 are not represented at all in its NW parts. From WOOD's records
we learn that 130 species are recorded from the Arabian Sea, 88 from the Red Sea and
57 from the Gulf of Aden, but only 2 from the Persian Gulf. The last figure is obviously
a result of the lack of information relating to that environment, as will be shown below.
While the pattern of a decrease in the number of species from the Arabian Sea towards
the Red Sea is dearly evident in the distribution of phytoplankton, there are a number
of species considered as endemic to the Red Sea. Among these, the following may be
noted: Dinophysis caudata, D. maris rubrt and D. miles of the dinoflagellates and
Trichodesmium erythraeum of the filamentous blue-greens, the latter species supposed to
occur at times in massive concentrations imparting to the Red Sea waters their characteristic coloration.
While the available data regarding phytoplankton relations in the areas under
B. KIMOR:
Finally, FROt-.'TIER (1963 a) measuring the quantitative distribution of zooplankton
by mm 3 per I m of advancing net, points to the NE part of the Arabian Sea as one of the
richest with values reaching up to 982 mm 3 , while in the main basin of the Arabian Sea
the values fluctuate between 25 - 65 mm 3 • Abrupt differences in zooplankton biomass
have been established by the same investigator in different areas of the Persian and Aden
Gulf, depending on whether the stations are coastal or more offshore and other factors.
The evidence emerging from these sources, despite the different parameters used,
indicates a higher level of plankton productivity in the NW part of the Arabian Sea,
more especially in the coastal areas, than in the Red Sea in general and its northern parts
in particular.
III. Phytoplankton
From a qualitative standpoint the 3 regions under discussion belong, according to
SUKHANOVA (1962 b), to the "Basic Indo-oceanic complex" whereby several species of
dinoflagellates common to the whole of the tropical areas of the Indian Ocean constitute
an outstanding feature of the phytoplankton. These species are Pyrocystis pseudonoctiluca, Ceratium carriense, C. trichoceros and C. massiliense.
In a more recent work SUKHANOVA (1969) established important differences in the
diversity of species in the different parts of the Red Sea and the Gulf of Aden. Accordingly
the central part of the Red Sea is the poorest in species with more diverse populations in
the northern and southern parts.
The dinoflagellates in general seem to be more uniformly distributed in the whole
region while the diatoms exhibit a more discontinuous distribution and very rarely
produce the water blooms characteristic of other areas of the Indian Ocean (SUBRAHMANYAN, 1960). Among such cases SUKHANOVA cites Climacodium frauenfeldianum
as reaching higher numbers in the Gulf of Aden, while in the Gulf of Eilat a one-time
occurrence of a waterbloom caused by Stephanopyxis palmeriana was noted by the
author (KIMOR, 1970) in February 1958.
SUKHANOVA's findings (1969) that many species recorded from the Arabian Sea and
other parts of the Indian Ocean (SUBRAHMANYAN, 1958) are not found in the Red Sea,
are amply corroborated by WOOD (1963). Out of a total of 452 species of his checklist
of dinoflagellates recorded from the Indian Ocean, only 170 are represented in the areas
under discussion. Of the 47 genera comprising WOOD's checklist of species for the Indian
Ocean as a whole, 14 are not represented at all in its NW parts. From WOOD's records
we learn that 130 species are recorded from the Arabian Sea, 88 from the Red Sea and
57 from the Gulf of Aden, but only 2 from the Persian Gulf. The last figure is obviously
a result of the lack of information relating to that environment, as will be shown below.
While the pattern of a decrease in the number of species from the Arabian Sea towards
the Red Sea is dearly evident in the distribution of phytoplankton, there are a number
of species considered as endemic to the Red Sea. Among these, the following may be
noted: Dinophysis caudata, D. maris rubrt and D. miles of the dinoflagellates and
Trichodesmium erythraeum of the filamentous blue-greens, the latter species supposed to
occur at times in massive concentrations imparting to the Red Sea waters their characteristic coloration.
While the available data regarding phytoplankton relations in the areas under