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UWFL-49

HEALTH AND SAFETY

+2-

UNITED STATES ATOMIC ENERGY COMMISSION

RADIOACTIVITY IN THE REEF FISHES OFBELLE ISLAND ENIWETOK ATOLL APRIL1954TO NOVEMBER 1955

ByArthurD. Welander

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AppliedFisheriesLaboratoryUniversityofWashingtonSeattle,Washington

Technical Information Service Extensic

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r LEGAL NOTICE—,This report was prepared as m account of Government sponsored work. Neither the

United States, nor the Commission, nor any person acting on behalf of the Commission:

A. Makes any warranty or representation, express or implied, with respect to theaccuracy, completeness, or usefulness of the information contained in this report, or thatthe use of any information, apparatus, method, or process disclosed in this report maynot infringe privately owned rights, or

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This report has been reproduced directly from the best avaikble copy.

Printed in USA. Price $1.25. Available from the Office of Technical Services,Department of Commerce, Washington 25, D. C.

.?? ?&}, } : ‘ ,,

AEC Technical information Servtce Extension

Oak Ridge. Tennesee

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UWFL-49

RADIOACT~N IN THE REEF FISHES OF BELLE ISLAND

ENIWETOK ATOLL APRIL 1954 TO NOVEMBER 1955

by

Arthur D. Welander

Applied Fisheries LaboratoryUniversity of WashingtonSeattle, Washington

Lauren R. DonaldsonDirector

.

Operated by the University of Washington under Contract No.AT(45-1)540 with the United States Atomic Energy Commission

‘,.i

iii

.,

ABSTRACT

Studies of the radioactivity in reef fishes of Belle

(Bogombogo) Island, Enfwetok Atoll, were made during a period

of about one year following the atomic detonations fn 1954. “

Thirty-four different collections were ~de and 693 SPeCiIIIenS

were analyzed to determine the trend or decline of radio-

activity. The decline of radioactivity during the period

under study was generally similar in all species. The rela-

tive amount of radioactivity per gram of tissue was greatest

in the alimentary tract, with the liver, skin, bone and muscle

having successively lesser amounts. This relationship pre-

vailed throughout the period. The rate of decline was great-

est during the first 100 days, with a loss of 90 per cent of

the radioactivity during the period. Studies were made on the

variation of total radioactivity in the tissues and species,

on comparisons of the amount of radioactivity in the species

and in their food, and on comparisons of the decline of radio-

activity during the period with the decay of radioactivity in

tissues collected soon after the shots.

v

.,..\

CONTENTS

,, .#’&iiu” .

Page

,

‘..

.,

Introduction

Materials and Methods

Results

Trends or Decline in the Levels of’Radioactivity

Variation in the Samples

Co:n:,::n of the Decline of Radioactivity by

Comparison of the Decline of Radioactivity in Fishwith that of their Food and with Other Factors

Comparison of Decline with Decay of Radioactivity

Conclusions

References●

Appendix

1

6

6

9

14

14

20

27

29

31

,’

,.,.. ,..“ ,4

,.

‘1.’, ‘?{ ~’

vi

RADIOACTIVITY IN THE REEF’FISHES OF BELLE

ISLAND, ENIWETOK ATOLL, APRIL1954 TO NOVEMBER 1955

Introduction

Previous studies of the radioactivity in the fishes in the

Marshall Islands have been confined to single surveys made soon

after an atomic detonation, occasionally followed by one to

three resurveys a few months UP to three years later (~L-7>

UUFL-16, mL-19, ~L-~3, W-616 (~L-33)~ and ~L-43 )●

Trends in the levels or decline of radioactivity In the fish

populations could only be estimated by basing assumpt~ons on

physical decay.

The purpose of this investigation was to measure the trend

or decllne of radioactivity in the fish, to compare the decline

in different species, in some of the organs or tissues, and In

the environment and to compare the decline with the physical

decay of radioactivity.

Materials and Methods

Continuous, sequential studies of the amounts of radioactiv-

ity in the reef’fishes of Belle (Bogombogo) Island, Eniwetok

Atoll, were made from April 14, 1954, through November 1> 1955>

during and after the weapons testing program at Eniwetok and

Bikini Atolls. The Nectar shot of May 14, 1954, was the most

important in these studies, since the detonation occurred but

-1-

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-2-..

.,,

,,’

.;

‘ ,<,.

2,7 miles east-northeast of Belle Island, and thus contributed

the greatest amount of radioactivity to the Belle area. There

was however, residual radioactivity present from previous atomic

weapons detonated at Bikini Atoll and at Eniwetok.

Reef’fishes were collected in the vicinity of Belle Island

by ush.g rotenone, hook and ltie, or spear in depths ranging

from a few inches to about 12 feet. Almost all of the collec-

tions were made on the seaward side of the island in Area F

(Fig. 1) in a habitat contatilng approximately equal amounts of

coral and sand. The area is typical of the reef of the northern

portion of the atoll except that It sustained a certain amount

of physical damage because of its proximity to the shot.

Attempts were made to confine the specimens analyzed to

those fish which were typical residents of the Belle area, but

such efforts were not entirely successful. The fish collected

during the first month after Nectar shot consisted mainly of

goatfish and mullet, species which move along the north reef

from island to island. Typical reef residents such as grouper,

damselfish and surgeonfish appeared to be scarce during this

period. In all, 34 different collections were =de In 1954 and

1955 which ticluded 693 specimens) these rePresentlw 57

and 22 families of fishes. However, only 9 species f’Fom

lies were consistently present in the collections (Table

Appendix).

species

9 fami-

1 and

The collections and treatment of data were similar to those

in earlier investigations by the Applied Fisheries Laboratory.

For complete details see ~-616 (~-33)c The sPeclmen9 were

.

WIND ROSE

!-.~- ...\ . . ...- -=. *..------ -, . ..

\ ...,

/SOUNDINGS IN FATHOMS

-., -./ ‘--

.-”,

AREA F\

BELLE

ISLAND

AREA G

/

AREA E

Fig. 1. Map of the north reef and islands of Eniwetok Atoll(top) with an enlarged map of Belle Island (bottom) showingtypical current patterns. The wind rose indicates prevailingwinds. . L

, ,. ,,.~, ,

Lnoooco*mlnlnrl

F1

rlomooLnun=tlnl.n

mq--lnH

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r+curlooCud Cum*d Al-i

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co

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co

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m

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-6-

put on ice as soon as possible after collecting and placed in

a freezer on being returned to the laboratory. Tissues were

dissected, weighed, and dried at the Enlwetok laboratory. The

tissues taken were skin, muscle, bone, liver and viscera (diges-

tive tract and contents) from the larger fish, or like tissues

were pooled from a number of small fish of the same species,or

entire fish were used. At the Unfverslty of Washington

laboratory, the dried samples were ashed at temperatures up to

540° C, cooled, slurrled, dried and counted in an internal gas-

t?lowcounting chamber. The total number of plates resulting

from all 34 collections was 2,167 (averaging about 64 plates

per collection).

All counts for radioactivity were corrected to the date of

collection, the decay f’actorsfor all Eniwetok samples being

based on a soil sample collected at Belle Island May 15, 1954.

Corrections were also made for self-absorption, backscatzer,

geometry and colnctdence. The radioactivity Is expressed in

microcuries per kilogram of wet tissue. Disintegrations per

minute per gram can be converted to microcuries per kilogram

using the relationship uc/kg = (2.2) (10)3 d/m/g.

Results*..

Trends or Decline in the Levels of Radioactivity

General trends of the radioactivity in the fish collected

at Belle Island are shown in Figure 2. Lties connecting the

points for data on musole and liver tissue reveal trends similar

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to those in other tissues. Differences are greatest in vis-

cera in which the amount of radioactivity is much greater than

in liver tissue the first 100 days; after this period the two

tissues decline at about the same rate. Bone and skin fluctu-

ate about a common intermediate range between muscle and liver,

the muscle always having the least radioactivity on a per-gram-

wet-weight basis.

During the first 100 days all tissues show a decrease in

radioactivity of more than 90 per cent from early post-shot

levels. By the 250th day the tissues had reached preshot lev-

els, which, at Enlwetok, were higher than normal because of

other detonations set off in previous tests.

The more or less consistent relationship of one tissue to

another during the decline of radioactivity may indicate com-

paratively slight differences in selective uptake in the five

tissues. An approximation of the relationship was obtained by

dlvlding the total

of the same tissue

age amount present

amount of radioactivity in all the samples,

by the number of samples to give the aver-

on a per-gram-wet-weight basis for the

period of April 1954 to November 1955. The following results

were produced:

Skin Muscle Bone Liver Viscera

Average uc/kg 11 1.0 9.8 29 ?7

Percent of total-of 5 tissues 8.3 0.8 7*7 22.9 60.3

The relationship varies depending on the time after shot and

.e

-1o-

The amount of contamination would, in turn, be subject to such

variables as tides, winds and currents. Biological variables,

such as migration of the fish, mortality, influx and outflow of

breeding populations and their young also could contribute to

the variation.

In order to determine

lations of the coefficient

the extent of’the variation, calcu-

of variation (V) were made (1) by

families, using four or more specimens for the calculations

(Table 2) and (2) by date, using muscle tissue from all fami-

lies combined (Table 3).

The data In Table 2 indicate that there are differences in

the coefficient of variation between families, i.e., distinctly

high in goatfish and mullet, and between tissues, averaging

highest In viscera. The average coefficient of variation for

all families and all tissues combined was 56 per cent. By

omitting the goatfish and mullet In the calculations the average

is lowered to 3’7per cent. The latter value is similar to that

found for algae (37%) (Palumbo, 1257) and for invertebrates

(Bonham, 1957).

The fact that goatfish and mullet prefer the open sandy bot-

tom areas of the reef, moving in schools from islandto island may

account for the higher coefficient of variation in these fishes.

The average coefficient of variation is much greater when

samples of mixed families or species are used. Table 3, h which

the data for muscle tissue are summarized, Indicates that the

coefficient varies from 16 to 209 per cent. The coefficient of

varfation of muscle in all the collections averages 97 per cent,

-11-

Table 2. COeffiCi8nt8 of V=iathn averaged for eachfamily of fish as to tissue. Calculationsare based on four or more fish with thenumber of aoefflcients used in parenthesis.

Familycommonname Skin Muscle Bone Liver Viscera Entire Av.

Butterflyfish

Cardinal fishDamselfish(30atfish

GrouperHalfbeakHerringMullet

Parrot fishSqulrrelfishSurgeonftshWrasse

Averages

Averageswithoutgoatfish andmullet

24(4)[)

27 5 29(4)[1

;; ~ 48(4)

[

34 22)31 1 32 2

16(2) 16 2I72(6) 66(6) 60(6) 79(6) 82(6) 72 30)

—— .— .—

53(32) 55(39) 50(33) 61(37) 69(33) 27(11)56(185)

27(16) 35(22) 28(17) 42(20) 57(17) 27(11) 37(103)

p,% “,

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-12-

Table 3. Comparison of average uc/kg and V in muscle tissue sam-ples with and without goatfish and mullet and with andwithout combined samples.

4-Pj-54 23 0.0574-22-54 3: :.:~84-25-54 .

10 21 0.057 48 17 0.049 311; :.;;7 ~:

●

5 1.4 72

9 1.1 107

31 1.5 97

983

2

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34431

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5-15,16-54

5-17-19-54

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93

125

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46 10 4622-5)45-26,28-54

1.9 1*9

19 3.8 2 19 3.8

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6~l;-546-19-546-25-54

2.82.22.82.71.5

2.80.261.62.81.6

927~i

14 415

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1056525 10 22

7-1-547-8-54

0.831.03

55:9

J.421.2

47531

0.440.410.190.410.22

52674260

0.340.340.97

8-5-548-12-548-~9-54

0.610.220.41

665

3098

952 8

0.150.250.25

2343430.41

9-7-54 14 0.21 5 6 0.24 49

lcl-5-54

11-2-54

11 0 ● 091 8 11 0.091

0.16

10 0.092 2’7

0.1625 11 25 15 0.098 23

am-nd

-13-

Table 3 (oontinued)

Samples without combined platesAll With goatfish and Without goatfishspecimens mullet and mullet

12-1-54 22 0.11 8 22 O*11 100 8 12 0.076 71 6

1-18-55 14 0.052 5 14 0.052 72 5

2-9-55 21 0.074 10 14 0.O99 124 8 8 0.051 50 6

3-21-55 20 0.054 6 8 0.047 31 4 3 0.047 21 3

11-1-55 33 0.019 8 33 0.019 65 8 28 0.016 38 7

u

-14-

but when goatfish and mullet are excluded the average is

53 per cent.

Comparison of’the Decline of Radioactivity by Species

A comparison of the decllne of radioactivity in two spe-

cies with different feeding habits is made tn Figures 3 and 4.

Surgeonfls~ with herbivorous habitq and grouper,with carnivor-

ous habi.ts,wereselected as representing the conditions

probably prevailed in the fish in the vicinity of Belle

For coxnpartsonsof other species, reference may be made

ures 7 through 10, which depict the decline in goatfish

that

Island.

to Fig-

and

mullet tissues. As has been pointed out, goatfish and mullet,

because of their movement along the reef from island to island,

are not strictly comparable to Belle Island “resident” fish,

and the decllne trends apparently reflect these differences.

Surgeonflsh and groupers were obtained fairly regularly

throughout the period of investigation. The former feed prin-

cipally on filamentous algae (Dawson, et al., 1955), whereas——

the groupers feed principally on fishes. The radioactivity in

the surgeonfish, Figure 3, declines at a greater rate than that

of the groupers, Figure 4, for all tissues for the first 50 to

100 days after

fish contained

as that of the

the shot. For example, muscle tissue of surgeon-

approxlmately four times as much radioactivity

grouper immediately after the shot, but by 125

days the two species contained stmllar amomtsc

Comparison of the Decllne of Radioactivity in Fish with that oflr Food and with Other F’actorq

In Figure 5 the radioactivity in surgeonfish viscera is

.-. . ...

8

.

l-lt3)cd E>00

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x+++x

x

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1,,1, 11111~+ x~

1 1 I 1 I a I 1 1 1 1 1 t I m I Ilfil I I I000 ~ o ~ u-)

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I’”11 I 1 1 11“’’’’”

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-18-

compared with that tn algae and found to be quite slmlla~ as

would be expected in a species which is principally herbivor-

ous. The decline h the radf.oacttvltyof sea water is Included

on a different scale to indicate the dependence or similarity

in the trends. Algae are dependent on

activity, which they concentrate up to

(Palumbo, 1957). The surgeonfi.shtake

sea water for their radio

several thousand times

in considerable amounts

of radioactive material by feeding on the algae. The data from

Belle Island (an area in which the supply of radioactive mater-

ial is only slowly decreasing) indicate that, for every mlcro-

curle of’radioactive material ingested into the alimentary tract,

about 0.55 mlcrocurles are distributed to the skin, muscle, bone

and liver combl.ned.

ln Figure 6, the decline of radioactivity in the liver tis-

sue of omnivorous fishes 1s compared with that of the sea cucum-

ber gut contents (Bonham, 1957) and algae. The similarities

appear to be marked during the early period of decline, with

liver ttssues of omnivorous fishes and sea cucumber gut averag-

ing

tus,

greater amounts of radioactivity than algae at 531 days.

Sea cucumber gut oontent 1s made up mostly of coral detrL-

slnce this invertebrate obtains its food from,thls material.

Coral fragments are also found abundantly In the alimentary tract

of the mullet, a detritus feeder, along with plant and animal

material. However, comparisons of the decllne in these two or-

ganisms in Figures 6 and 10 show marked differences in the trends

of radioactivity. It will also be noted that the decline of

radioactivity in mullet tissues is considerably different from

. .

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that of other fish tissues. Goatfish viscera (Fig. 7), on the

other hand, declines similarly to that of sea cucumber gut,

the liver of an omnivore, and to some degree, algae. Goatfish

f’eedlargely on braohyuran crabs, which, i.nturn, feed on alga~

dead fish, etc., so that the diet of goatfish is, to a certain

degree, comparable to that of omnivorous fishes.

Comparison of Decline with Decay of Radioactlvit~

F1.gures7 through 10 show certain marked differences be-

tween decline and decay of radioactivity in the same tissues

for both goatfish and mullet. In goatfish the differences are

evident in the first 100 days after shot, while i.nmullet the

differences are greatest for the first 150 to 200 days. Vari-

ations due to sampllng and other causes, which have been dis-

cussed in a previous section, might explati some of the differ-

ences. Also they might be due to the differential affinity of

various species for shorter-lived isotopes. In goatf’ishthe

radiatton varies to around 50 to 170 uc/kg for liver, about 20

to 50 uc/kg for bone and 3 to 7 uc/kg for muscle.

Similarities in the decay curves are shown in Figures 7,

8, 9, 10, and 11. For example, liver decay in goatfish (Fig.8)

is similar to that of mullet liver after 100 days; muscle decay

in goatfish is similar to surgeonflsh liver and surgeonflsh bone

after 200 days; while bone decay of goatflsh is similar to bone

decay of mullet and surgeonfish after 100 to 250 days. Dissimi-

larities in the decay curves appear to be greatest during the

first 100 to 200 days after the shot, the curves tending to

. . .

the

#

fish

ilgae,

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-26-

approach each other in pattern with passage of time. During

the early period after the shot there is, of course, a greater

variety of radioactive isotopes present than later, and there

is some indication that selective uptake might be more marked

or selective exclusion less marked during this period. As

the shorter-lived isotopes decay and decrease in importance,

leaving fewer radioactive materials available, the decline and

deoay of radioactivity in the dif’f’erentttssues and species

show greater similarities.

The data presented do not permit exact distinctions be-

tween tissues or between different species on the basis of

differences h the uptake of radioactive materials. It appears

from the decay curves and the decline trends that the fish

tissues differ mainly in orders of magnitude rather than tn

quality after the first 100 days, although there is the possi-

bility of diff%rent

present.

Radiochemical

lected two to three

isotopes with sfmilar half lives being

analysis done within two months on fish col-

months after shot contained MnS4, Fe55,Co57,

Co58j Co60, and Zn65, with Fe55 and Zn65 as the dominant isotopes.

Fish collected within one month after the 1954 shots and analyzed

January 1957 contained 95 percent Fe55; Nhi54,C057, and Co60

(Lo~an, pal~bo ~d South, 1957) contributed the re~lnder of

the radioactivity. There may be fission products in the fish

the first few weeks or months after the shot, but after four or

five months fission products contribute very little, if any, to

the total radioactivity in the fish.

3r

3#

1

Ld

rs

.

?l-

f7,

Ipes,

lzed

P

?

--.-. --”

-27-

Conclusions

BioIogl.caldecline of radioactivity h the fishes of Belle

Island, Eniwetok Atoll, 1s generally similar in all species.

Differences which are evident may be attributed to differences

in fe~dtig habits and, these differences, which appear greatest

during the first 100 to 200 days after shot, my be attributed

to differences in the uptake and retention of the short-lived

isotopes. The decline of the radioactivity in omnivorous fishes

is more rapid than that in carnivorous fishes so that 200 days

after shot the amount of radioactivity in the two types of fish

appears to be quite similar. It might be postulated that omni-

vorous fishes Ingest food which contains comparatively greater

amounts of the

vorous fishes.

The decay

shorter-lived isotopes than the food of carni-

of radioactivity In the tissues of fish from

Belle Island also differs during the first 100 days after the

shot, reflecting, to some degree, the unstable ecological condi-

tions prevailing in that region at the time.

The relationship of the amounts

in each of the five tissues examined

sistently and substantiates findings

of radioactivity retained

prevails more or less con-

of previous Investigations.

The greatest per-gram concentration of radioactive materials

occurs in the alimentary tract with the liver, skin, bone and

muscle having guccesgi~ely lesser amounts. The greatest vari-

ation from this pattern appears during the first few weeks after

shot.

:$1 ,.’f

-28-

The rate of decline of the radioactivity in almost all of

the fish was greatest during the first 100 days,during which

time more than 90 percent of the post-shot radioactivity was

lost.

The variation in amounts of radioactivity in tissues from

the same collection of fish, as measured by the coefficient o’

variation (V), may be due to several causes, prominent of whi ;h

are the differences between different species of t’ish. The vari-

ations definitely indicate that large samples of many species

are necessary to obtain rellable information on the amount of

radioactive materials present in fish populations.

... —--— -- .-1

1.

2.

3.

4.

6.

7.

8.

9.

10.

-29-

REPERENCES

Applied Fisherl@s Laboratory, University of WasMngtontRadiobiological r@sWvey of Bikini Atoll during thesummer of 1947. U. S. Atomic Ener~ commission reportuWFL-7 (1947)0

Applied Fisheries Laboratory, Universitt

of Washington.Bikini radlobiologlcal resmvey of 19 ~. U. S. AtomicEnergy Comission rePOrt UWFL-16 (1949).

Appll@d Fisheries Laboratory, University of Washington.Eniwetok radiological resurvey July 1948. U. S. At’omitEnergy Commission report --19 (1949).

Applied Fisheries Laboratory, University of Washington.yt~.;&ological s~vey of Bikini, Eniwetok and Likiep

July-August 1949. U. S. Atomic Energy Com-mission-report UWFL-23 (1950).

Applied Fisheries Laboratory, University of Washington.Radiobiological studies at Eniwetok Atoll before andfollowing the Mike shot of the November 1952 testing

U. S. Atomic Energy Commission report%%%”(1953).

Applied Fisheries Laboratory, University of Washington.Radiobiological resurvey of Rongelap and AilinginaeAtolls, Marshall Islands, October-November, 1955.U. S. Atomic Energy Commission report WFL-43 (1955).

Palumbo, Ralph F. @take of iodine-131 by the red algaAs ara o SIS taxlformls.~f Washi ~ton.

Applied Fisheries Laboratory,U. S. Atomic Energy Commis-

sion report UWFL-44n 1955).

Bonham, “Kelshaw. Radioactivity of invertebrates andother organisms at Eniwetok Atoll during 1954-55.Applied Fisheries Laboratory, University of Washington.MS.

Bonham, Kelshaw. Statistical variability in radioac-tivity of field sam les of biological materials at

tBelle Island in 195 -55. Applied Fisheries Labora-tory, University of Washington. ~.

Palumbo, Ralph F. Radioactivity in the algae at thePacific proving around. Applied Fisheries Laboratory,University of Washington. MS.

.

-30-

11. Lowman, Frank G., Ralph F. Palumbo and Dorothy J. South.The occurrence and distribution of radioactive non-flsslon products in plants and animals of the PacificProving Ground. Applied Fisheries Laboratory, Univer-sity of Washington. U. S. Atomic Energy Commissionreport UWFL-51 (1957).

12. Dawson, E. Y., A. A. Aleem and B. W. Halstead. Marinealgae from Palmyra Island with special reference to thefeeding habits and toxicology of reef fishes. Occasion:Papers, Allan Hancock Foundation, No. 17, pp. 1-39 (195!

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