NOTE

Destruction of Marine Flora and Fauna in FijiCaused by the Hurricane of February 19651

M. J. COOPER2

EARLY IN FEBRUARY 1965 a hurricane passedclose to the main islands of Fiji. This hurricanebrought not only widespread flooding on VitiLevu, the largest island in the gro up, but alsocaused unexpected and severe damage to thecoral reefs in the southern part of Mbau W ater ,on the east coast of Viti Levu.

Mr . P. R. Rakoroi, the Officer in Charge atthe New Zealand Meteorological Service atLauthala Bay, gave me the meteorological de­tails and plotted the storm centr e on the accom­panying map ( Fig. 1). The storm began as asmall tropical depression to the west of WallisIsland and developed into a severe hurric aneas it travelled southwest towards Fiji. Th e mapshows the storm centr e on February 7 to bealmost stationa ry, hut it was actually movingin a small clockwise circle over northwest BlighWater before continuing its southwest move­ment . By February 8 the hurricane was travel­ling south-southwest, but much more slowlythan is usual with these tropical storms . How­ever, by February 9 it had at last picked upspeed and begun to move southwes t away fromViti Levu. Because the hurricane moved soslowly on the 7th and Bth, torr ential rain whichalways accompanie s these tropical storms fellon the island of Vit i Levu for a far longer timethan is normal. The rainfall figures for Koro-o,

1 Contribution No. 23 1, Hawaii Institute of Ma­rine Biology, Univ ersity of Haw aii. Manu script re­ceived April 28, 1965.

2 Consultant, Ha waii Marine Laboratory, Uni versityof Hawaii. H ome address : 28 Statham Street, LaucalaBay, Suva, Fiji. Study in parr supp orted by U. S. Pub­lic Health Service Gr ant EF-002l 6.

the meteorological station high up on the Rewawatershed in north Viti Levu, and for themeterolog ical station at Laucala Bay on thecoast in southeast Vit i Levu, are as follows:

KORO-O LAUCALABAY

inches inches

Feb. 6 1.567 11.87 1.7K8 31.09 8.259 6.79 3.56

10 0.36 0.14

Mr. ]. R. Deverell, Distric t Officer, N ausori,gave me detai ls of the flooding caused by thisheavy rain. The ground in the hills of the Rewawatershed was completely waterlogged by the11 inches of rain which fell on February 7, sothat the enormous quantity of water from the31 inches which fell the next day simply pouredstraight off the hills into the creeks which arethe start of the Rewa river system. As this massof water flowed down to the Rewa River, thetributaries rose to alarming heights. In somegorges the water was up to 100 feet abovenormal. Th e Rewa itself at N ausori, where theriver is very wide and there is a large floodplain, was 15 fr above norm al at high tide, andthe whole of Rewa delta was under water.

Th e main mouth of the Rewa, the N ukulauMouth, is on the southwest side of the delta.The continuous flow of fresh-water from thismouth is sufficient to keep open a large passagethrough the barrier reef. This passage was ableto carry off the extra water that came downthe river during the storm before it caused any

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138 PACIFIC SCIENCE, Vol. XX, January 1966

FIG. 1. Track of Hurricane, February 196 5.

Sakanasa Rokotuidau and other officers of theCo-operatives Department, who described it as"a brown stain on the sea" which covered the

. south end of Mbau W ater and stretch ed outinto the ocean over the barrier reefs.

For some days after the floods a few deadfish, mostly parrot fish and wrasse, were foundon the beaches round Laucala Bay, the Suvapeninsula, and Lami. Fishermen reported find­ing dead fish off the N asoara and Nasilaimouths of the Rewa, but it is not uncommonfor a few dead fish and shells to be found aftervery heavy rain . However, on February 15 areport came in from Tomberua Island that thesea round the island was covered wi th thou ­sands of dead fish. I made a trip down theRewa to Tomberua Island on Februar y 17 tosee for myself the extent of the damage, and to

talk about it with the people of Kamba village.Mr. McHugh, owner of Tomberua Island,

and the Kamba villagers told me about thedead fish. On February 13 and 14, while theywere attempting to salvage a small cut ter whichhad been wrecked on the outer reef during thestorm, they passed many dead fish floating onthe water . They said that the fish lay in longswathes in the hollows of the waves, 10 fr wide,several fish deep, and stretching as far as theycould see. There were fish of all kinds, a fewvery large fish, most of which had been mauled ;many hundreds of medium-sized fish, smallbarracudas, parrot fish, wrasse, red and greysnappers, groupers, eels, surgeon fish, mullets ,puffer fish, and trigger fish; many thousands ofvery small fish, brilliantly coloured damsel fishand butterfly fish, small eels, and young fish ofall kinds. On February 15 and 16 many of thesefish were washed up on the beach at Tomberua,where they were buried, but very few were castup on the beaches of the Kamba peninsula.The Kamba people , who are expert fishermen,told me that they had never heard of anythinglike this happening before. The floods of 1929,1931, 1954, and March 1964, although causingheavy damage to property and food crops andmortality amongst livestock, did not affect anyreefs to this extent.

I walked on the Tomberua reef at half tide

179E18 0178~]+__...I,;,,~_,l,;,.;,._--'__"""'__'"

.great damage to the coral reefs in that area.The Navuloa Mouth, one of several minormouths of the Rewa, is on the north side ofthe delta. Th is mouth runs into the south endof Mbau Water, a lagoon-like area boundedto the west by Viti Levu, to the south by theKamba Peninsula, and the east by a large lux­uriant coral reef; to the north it joins BlighWater, northwest of Ovalau Island 25 milesaway. The amount of fresh-water carried bythe Navuloa Mouth had not been sufficientto prevent the growth of corals in the areawhich abounded in fish, mollusks, turtles, andother marine life.

During the February floods the left bank ofthe Rewa River just below Wainibokasi vil­lage gave way, and a mass of floodwater pouredinto an old bed of the river and was carriednorthwest across the delta to flow into the seathrough the N avuloa Mouth as a great brown ,muddy stream. This was seen from Colo-i-Suva,the highest point on the Suva peninsula, by

Destruction of Mari ne Flora and Fauna-COOPER 139

VITILEVU

40'

FIG. 2. Map of Mbau W ater s, Fiji.

140

and wandered slowly along the edge of the re­ceding water. I stayed Out on the reef until thetide turned and began to cover the reef again.Nearly every living thing, plant or animal, onthe reef was dead. The reef itself was a dullbrown, the sand a dull grey. In places therewere patches of white or black, the putrefyingremains of unidentifiable sea creatures. Shellsof many kinds were lying on the sand, on whathad presumably been a mat of green alga, nowa yellowish-grey rotting mass. There werethorny oysters gaping white on the stones,there were cockles, clams, tellins, scallops, au­gurs, black-mouthed pinnas, pink olives, andthe carapaces of sand dollars and heart urchinsscattered everywhere, with foul-smelling clumpsof rotting Halim eda. Farther out among the tidepools were many kinds of cones, miters, cow­ries, limpets, strombs, spider shells, and chi tons,together with the fluorescent whiteness of burstand rotting holothurians. Some of the shellshad already been occupied by a species of blackand yellow hermit crab, but these crabs werevery languid and obviously dying. I turned overa few stones : they were black and slimy under­neath, a dying worm or two floated out, andthe decaying remains of a brittle star. Therewere no small sponges, algae, anemones, shelleggs, or any other organisms left alive underthe stones or in the sand, which was black andfoul under the surface. On the very edge of thereef the smell was really horrible. There werelarge putrefying masses of soft corals, decay­ing remains of many unidentifiable creatureslying on the dull, brown, dead corals. I peeredinto the deeper water. Even the sea seemed tosmell of decay, and I could see no sign of anycoloured living coral nor the bright green ofany alga. All seemed dead.

This dismal picture was relieved a littlewhen I found a very lively, very belligerentred-eyed crab, and, in one or two of the deepertide pools near the edge of the reef, I foundthat a few small fish had already moved in, orperhaps had survived the kill. They were veryfew in number and appeared to be a species ofgoby, one small Pleisops, and three species ofAbudefduf, possibly sordidus, zonatus , and sax-

PACIFIC SCIENCE, Vol. XX, January 1966

atilis. I noticed that these live fish were in poolsthat had a rock or clear sand bottom, with norotting algae, and which possibly had a higheroxygen content than other pools. In one shal­low pool I found a beautiful green and bluecowfish, Lactoria sp., which was grazing on rot­ting algae and appeared unaffected by the foulconditions. I saw several rather large eels, Gym­notborax picta, which were swimming withtheir heads sticking Out of the water andseemed completely fearless. On my way backto the island I found several apparently healthycolonies of a species of Nerita and one smallbright green tuft of Enteromorpha growing ina strong current near the edge of the reef . Afrequent splashing sound attracted my attentionand, wading Out into the sea, I found it wascaused by a huge school of sardines, or "dan­iva" (Clupea sp.?), frantically feeding on thecloudy brown detritus from the reef.

The Kamba people told me that during theflood the whole sea around Tomberua Islandoff the Kamba peninsula, and right OUt ave;the reef by Mumbualau Island was muddy , andthat when they swam in it they found that itwas quite fresh, "like the river." It seems cer­tain that this freshening of the water was re­sponsible for the initial mortality. The Depart­ment of Agriculture says that there had beenlittle or no use of pesticides or herbicides priorto the floods which might have been washed offthe land into the rivers, nor does there seemto have been any other form of pollution whichcould have caused the damage . The many fishand other plants and animals killed by thefresh-water began to putrefy, and this in turncaused the death of other organisms by usingup the available oxygen and polluting the reefwith hydrogen sulphide and other products ofdecomposition.

It will be very interesting to watch the re­generation and repopulation of these reefs tosee if there is any marked or permanent eco­logical change. In recent years some fish caughtin Mbau Water have been known to causeciguatera poisoning; these are chiefly Letbrine:miniats«: and Lutianus bohar, although otherlerhrinids may be poisonous as well. Cases of

Destruction of Marine Flora and Fauna-COOPER

poisoning from fish caught there were ratherinfrequent but continual. According to onehypothesis, ciguatera increases when "new sur­faces" are exposed to settlement by blue-greenalgae ( Randall, 1958) . As yet no cases of fishpoisoning have been reported. The Kamba peo­ple, who traditionally fish in these waters, aremost concerned in case the poisoning shouldbecome much worse as a result of the extensivedamage and are watching the area with greatinterest.

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REFERENCES

COOPER, M. J. 1964. Ciguatera and other marinepoisoning in the Gilbert Islands. Pacific Sci­ence 18(4 ) :411-440.

DERRICK, R. A. 1946. A History of Fiji. Vol. 1.Government Press, Suva.

RANDALL, J. E. 1958. A review of ciguatera,tropic al fish poisoning, with a tentative ex­planation of its cause. Bull. Mar. Sci. Gulfand Carib. 8 (3 ) :236-267.