140 
and wandered slowly along the edge of the re- 
ceding water. I stayed out on the reef until the 
tide turned and began to cover the reef again. 
Nearly every living thing, plant or animal, on 
the reef was dead. The reef itself was a dull 
brown, the sand a dull grey. In places there 
were patches of white or black, the putrefying 
remains of unidentifiable sea creatures. Shells 
of many kinds were lying on the sand, on what 
had presumably been a mat of green alga, now 
a yellowish-grey rotting mass. There were 
thorny oysters gaping white on the stones, 
there were cockles, clams, tellins, scallops, au- 
gurs, black-mouthed pinnas, pink olives, and 
the carapaces of sand dollars and heart urchins 
scattered everywhere, with foul-smelling clumps 
of rotting Halimeda. Farther out among the tide 
pools were many kinds of cones, miters, cow- 
ries, limpets, strombs, spider shells, and chitons, 
together with the fluorescent whiteness of burst 
and rotting holothurians. Some of the shells 
had already been occupied by a species of black 
and yellow hermit crab, but these crabs were 
very languid and obviously dying. I turned over 
a few stones: they were black and slimy under- 
neath, a dying worm or two floated out, and 
the decaying remains of a brittle star. There 
were no small sponges, algae, anemones, shell 
eggs, or any other organisms left alive under 
the stones or in the sand, which was black and 
foul under the surface. On the very edge of the 
reef the smell was really horrible. There were 
large putrefying masses of soft corals, decay- 
ing remains of many unidentifiable creatures 
lying on the dull, brown, dead corals. I peered 
into the deeper water. Even the sea seemed to 
smell of decay, and I could see no sign of any 
coloured living coral nor the bright green of 
any alga. All seemed dead. 
This dismal picture was relieved a little 
when I found a very lively, very belligerent 
red-eyed crab, and, in one or two of the deeper 
tide pools near the edge of the reef, I found 
that a few small fish had already moved in, or 
perhaps had survived the kill. They were very 
few in number and appeared to be a species of 
goby, one small Pleisops, and three species of 
Abudefduf, possibly sordidus, zonatus, and sax- 
PACIFIC SCIENCE, Vol. XX, January 1966 
atilis. I noticed that these live fish were in pools 
that had a rock or clear sand bottom, with no 
rotting algae, and which possibly had a higher 
oxygen content than other pools. In one shal- 
low pool I found a beautiful green and blue 
cowfish, Lactoria sp., which was grazing on rot- 
ting algae and appeared unaffected by the foul 
conditions. I saw several rather large eels, Gym- 
no thorax picta, which were swimming with 
their heads sticking out of the water and 
seemed completely fearless. On my way back 
to the island I found several apparently healthy 
colonies of a species of Nerita and one small 
bright green tuft of Enteromorpha growing in 
a strong current near the edge of the reef. A 
frequent splashing sound attracted my attention 
and, wading out into the sea, I found it was 
caused by a huge school of sardines, or "dan- 
tva” (Clupe a sp.?), frantically feeding on the 
cloudy brown detritus from the reef. 
The Kamba people told me that during the 
flood the whole sea around Tomberua Island, 
off the Kamba peninsula, and right out over 
the reef by Mumbualau Island was muddy, and 
that when they swam in it they found that it 
was quite fresh, "like the river." It seems cer- 
tain that this freshening of the water was re- 
sponsible for the initial mortality. The Depart- 
ment of Agriculture says that there had been 
little or no use of pesticides or herbicides prior 
to the floods which might have been washed off 
the land into the rivers, nor does there seem 
to have been any other form of pollution which 
could have caused the damage. The many fish 
and other plants and animals killed by the 
fresh-water began to putrefy, and this in turn 
caused the death of other organisms by using 
up the available oxygen and polluting the reef 
with hydrogen sulphide and other products of 
decomposition. 
It will be very interesting to watch the re- 
generation and repopulation of these reefs to 
see if there is any marked or permanent eco- 
logical change. In recent years some fish caught 
in Mbau Water have been known to cause 
ciguatera poisoning; these are chiefly Lethrinus 
miniatus and Lutianus bohar, although other 
lethrinids may be poisonous as well. Cases of 
