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NOTES
AND
COMhfENT
291
A BLOOMOFTHEPLANKTONIC
BLUE-GREEN ALGA, Trichodesmium
~~~$&~~~~,INTHEToNGAIsLANDs
The planktonic blue-green alga, Trichodesmium
erythraeum
Ehrenberg,
also
known as SJcujaella erythraea (Ehrenberg )
J. de Toni, has a wide distribution in tropical and subtropical waters of the world.
From time to time there have been reports
of its occurrence at various localities in
immense numbers; these reports were summarized by Brongersma-Sanders
( 1948,
1957). Except for the waters of the East
Indian Archipelago, where Trichodesmium
blooms have been reported from the Java
Sea (Delsman 1939), the east coast of
Borneo ( Mohler 1941) and the Arafura
Sea ( Moseley 1892; Murray 1895)) the
only accounts known to us of blooms of
this alga in the Pacific Ocean are those of
Yonge ( 1930), who stated that red water
caused by Trichodesmium
was frequently
observed near Low Isles during the British
Great Barrier Reef Expedition of 1928-1929,
and Wood ( 1963)) who reports that the
Trichodesmium “red tide” is an important
feature in the South Pacific and Indian
Oceans. Allen ( 1963) cites Wood as stating that Trichodesmium blooms may cover
hundreds of square miles near the Great
Barrier Reef. We believe, therefore, that
the occurrence of a bloom at Tongatabu,
Tonga Islands, is of interest.
On 19 January 1963 a “gray tide” was noticed along the northern coast of Tongatabu,
in the vicinity of the capital, Nuku’alofa.
The heaviest concentration was in the area
in front of the beach and boat dock at
Touliki, about 1.2 km east of the post
There was little
office in Nuku’alofa.
bloom beyond 20 m seaward of the outer
edge of the fringing reef, which is about
30-45 m from the beach. The color of the
bloom was mostly gray, with some pink to
light red patches. The gray color led some
observers to speculate that the water was
filled with volcanic ash from an undersea
eruption. The outer edges of the bloom
formed long parallel streaks.
The odor of the bloom was not noticeable
except near Touliki, where there was a
‘“weedy pond” smell. At the terminal stages
of the bloom, the stench resembled that of
chlorine and was strong enough to hinder
use of a road running parallel to the beach.
Toxic effects of the bloom were relatively
insignificant.
There was a limited mortality
among the small fishes, but most of the
fishes apparently were not adversely affected. Several children were observed
swimming in the most concentrated part of
the bloom, and they suffered no ill effects.
waded far into the
One of us (L.J.L.)
bloom to collect samples and did not notice
any irritation.
Samples taken in the bloom on 20 January 1963 with a small plankton net were
found to consist alrnost exclusively of the
filamentous
blue-green
alga, Trichodesmium erytlzraeum, the filaments of which
sheaves.
are grouped into characteristic
Part of a sample was sent to Dr. Francis
Sciences,
Drouet, Academy of Natural
who kindly confirmed our
Philadelphia,
The only other organisms
identification.
in the samples were a few harpacticoid and
cyclopoid
copepods, belonging
to nonpelagic genera. In contrast, samples taken
in the bay beyond the fringing reef in
November 1962 and August 1963 were
dominated by Calanoid copepods (mostly
species of Paracalanus and Acartia) and
chaetognaths.
The duration of the bloom at Tongatabu
was about 2 full days; it was almost completely gone by the evening of 20 January.
According to Chacko ( ISSO), Trichodesmium blooms in waters around Krusadai
Island, India, usually last 3-7 days.
In its odor and occurrence in streaks, the
Tonga bloom agrees \aith published accounts of Tric7.7oClcsn~ill~~z
from other localities. The gray color is atyljical; the color
has been described as dirty yellow, brownish yellow, reddish brown, brownish or
reddish, blood red, and red. King (1950)
states that it is yellowish at the height of
the bloom, becoming reddish brown when
the peak of growth is passed.
292
NOTES
AND
In the Java Sea, Delsman (1939) observed that Trichodesmium avoids brackish
coastal water and is usually found at some
distance from the coast. However, he did
find it close to shore where brackish water
was not present. Along the west coast of
Florida, King ( 1950) found Trichodesmium
in bloom abundance only within 56 km of
the shore and most commonly just off the
beaches. Ehrenberg (1830) reported an
outbreak of red water due to Trichodesmium in the Bay of Tor ( El TQr ) of the
Gulf of Suez; the red water occurred only
in the bay and not in the open gulf outside
of it. These records suggest a preference
for coastal water over oceanic water if
brackish water can be avoided. Unfortunately, we have, no information
on the
salinity at Tongatabu during the bloom.
Harmful effects associated with blooms
vary from negligible
amounts to rather
Reports of mortality are
severe mortality.
limited to waters around India (Chacko
1942, 1950; Chidambaram and Unny 1944)
and the East Indies (Veenhuyzen
1879;
Mohler 1941) . Although
Trichodesmium
blooms occur in the Atlantic ( Darwin 1839;
Agassiz 1888)) we have not found any reports of mortality resulting from them.
The factors that contribute to blooms
of Trichodesmium
are not yet known.
Weather conditions at Nuku’alofa during
the month of January 1963 were not exceptional. The sea temperature (estimated
from the midnight-0600
air temperature)
gradually increased from 23C on 1 January to 26C on 15 January, and the wind
direction gradually shifted from east-southeast through east to north. The change in
the wind direction may have increased the
flow of outside water into the bay through
Biha or Eastern Passage, but there is no
reason to relate such a possible increased
flow to the Trichodesmium bloom. Recent
findings
( Dugdale, Menzel, and Ryther
1961) showing that Trichodesmium thrives
in nutrient-improverished
water and fixes
atmospheric nitrogen have important implications for the generation of blooms.
Finally, we wish to point out that blooms
are not uncommon in Tonga, although they
COMMENT
have not been the subject of published acIn addition
to Trichodesmium
counts.
blooms, “red tides,” with more toxic effects,
are known.
THOMAS
E. BOWMAN
Division of Marine Invertebrates,
Smithsonian Institution,
Washington, D.C.
L. J.
Tonga College,
‘Atele, Tonga Islunds.
LANCASTER
REFEXENCES
A. 1888. Three cruises of the United
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Survey Steamer
Blake in the Gulf of Mexico, in the Carribbean
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States, from 1877-1880.
v. I. Bull. Museum
Comp. Zool. Harvard Coll., 14. 314 p.
fixing organisms
ALLEN,
M. B. 1963. Nitrogen
in the sea, p. 85-92. Zn C. J. Oppenheimer
[ ed.], Symposium
on marine microbiology.
Thomas, Springfield,
Illinois.
M. 1948. The
imporBRONGERSMA-SANDERS,
tance of upwelling water to vertebrate paleontology and oil geology.
Verhandel.
Koninkl.
Ned. Akad. Wetenschap.,
Afdel.
Natuurk.,
Sect. II, 45: 1-112.
1957. Mass mortality in the sea, p. 941-.
1010. Zn J. W. Hedgpeth
[ed.], Treatise on
marine ecology and paleoecology.
v. I, Ecology. Geol. Sot. Am. Mem., 67. 1296 p.
of
CHACKO,
P. I. 1942. An unusual incidence
Current Sci. Inmortality
of marine fauna.
dia, 11: 402.
1950. Marine
plankton
from
waters
-.
around the Krusadai
Island.
Proc. Indian
Acad. Sci., sect. B, 31: 162-174.
CHIDAMBARAM,
K., AND M. MUKUNDAN
UNNY.
1944. Note on the swarming of the planktonic alga Trichodesmium
erythrueum
in the
Pamban area and its effect on the fauna.
Current Sci. India, 13: 263.
DARWIN,
C. R. 1839. Journal of researches into
the geology and natural history of the various
Hafner
countries visited by H. LM. S. Beagle.
615 p.
Publishing
Co., New York-London.
(Facsimile
reprint of first ed., 1952).
DELSMAN,
H. C. 1939. Preliminary
plankton
investigations
in the Java Sea. Treubia, 17 :
139-181.
DUGDALE, R. C., D. H. MENZEL,
AND J. H. RYTHER.
1961. Nitrogen fixation in the Sargasso Sea.
Deep-Sea Res., 17: 297-300.
EHRENBEFIG,
C. G. 1830. Neue Beogachtungen
iiber blutartige
Erscheinungen
in Aegypten,
Arabien
und Siberien nebst eine iibersicht
und Kritik.
Poggendorf’s
Ann. Phys. Chem.,
AGASSIZ,
18: 477-515.
NOTES
J. E.
plankton
J. Florida
MOHLER,
W.
nomeen
Natuurk.
KING,
AND
1950. A preliminary
report on the
of the west coast of Florida.
Quart.
Acad. Sci., 12: 109-137.
A. 1941. Een blauwwieren-pheaan het strand
van Balikpapan.
Tijdschr. Ned. Indie, lOl( 3) : 75-
79.
H. N. 1892. Notes by a naturalist.
An account of observations
made during the
voyage, of H.M.S. Challenger round the world
in the years 1872-1876, under the command
of Capt. Sir G. S. Nares, R.N., K.C.B., F.R.S.,
and Capt. F. T. Thomson, R.N.
John Murray, London.
540 p.
MOSELEY,
293
COMMENT
JOHN.
1895. A summary of the scientific results.
Rept. Sci. Res. Voyage H.M.S.
Challenger
1872-76.
796 p. ( First Part) ;
797-1608 p. (Second Part).
VEENHUYZEN,
J. C. 1879. Communication
on:
Trichodesmium
erythraeum.
Natuurk.
Tijdschr. Ned. Indie, 38: 150-151.
WOOD,
E. J. F. 1963. Some relationships
of
phytoplankton
to environment,
p. 275-285.
Zn C. H. Oppenheimer
Led.], Symposium on
marine
microbiology.
Thomas,
Springfield,
Illinois.
YONGE, C. M.
1930. A year on the Great Barrier Reef.
Putnam, London and New York.
246 p.
MURRAY,
SELF-CLOSINGDEVICE FORSAMPLINGPLANKTONNEARTHE
SEABOTTOM~
The apparatus described here was designed to obtain samples of plankton from
1 This device was developed during an ecological study supported in part by National
Science
Foundation
Grant G-7141 to Dr. E. W. Fager of
Scripps Institution
of Oceanography,
and in part
Oceanography
Research
of
by Scripps
Tuna
Scripps Institution
of Oceanography
with funds
provided by U.S. Bureau of Commercial
Fisheries
under Contract 14-17-0007-28.
FIG.
1.
Diagram
near the sea floor. It can be used from a
small boat operating over a smooth bottom in shallow water.
Other apparatus designed for collecting
plankton in the immediate vicinity of the
bottom (Russell 1928; Bossanyi 1951; Wickstead 1953) and conventional conical nets
( Sverdrup, Johnson, and Fleming 1942)
have inadequate closing mechanisms or are
of self-closing
bottom
plankton
net.