Recovery of the Land Plants at Enewetak Atoll Following a Nuclear Detonation, Vol I, No. 2, PP 182-189

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RECOVERY OF THE LAND PLANTS AT ENIWETOK ATOLL Laboratory of Radiation Biology, Univmsitv of If ’ashington. Seattle, \t’ashing(on determine the rate of recovery of land plants damaged by the radiation, shock and heat blast of the Nectar detonation in 1954. .%t Belle Island seven plant species were tagged, measured and photographed before the detonation. .% approximately monthly intervals after the detonation for a period of ten months, and again after an interval of six months, the plants were observed and photographed. The first indication of recovery was observed on the eighth day, at which time buds were noticeable on stems of Scaez,ofa and :}le~$er;chmio’ia plants. In a month’s time, most of the plants had formed new leaves and some had produced flowers and ft uits. In six months. the general condition of the vegetation was similar to that which existed before the detonation. Two plants. Guettarda and Portulaca, which were unhealthy at ten months, had improved by the sixteenth month. Photographs of the recovery of some of the plants are included in this report, as well as a discussion of aqents other than radiation which have been reported to cause similar damage to plants of the coral atolls of the Pacific Ocean, ann~es 1954– 1957 afin de determiner la vitesse de restauration de plantes de p[eine terre endommagees par les radiations, le shock et Ie souffle thermique de l’explosion ,Nectar en 195+. A Belle Island, sept esp?ces de plantes ont c++ +tiquetfes, mesurees et photographi+es avant l’explosion. Les plantes ont ete observees et photographiees & des intervalles d’environ un mois pendant une periode de dix mois apres I’explosion et ensuite, apr+s un ddlai de six mois. Le premier indite de restauration a +te observe le huitieme jour, moment auquel des bourgeons ont ete releves sur es tiges de Scaevofa et AIessemckraidia. End@ans une p~riode d’un mois, la plupart des plantes avaient forme de nouvelles feullles et certaines avaient produit des fleurs et des fruits. En six mois, les conditions g+nerales de vegetation &taient redevenues semblables a celles qui existaient avant I’explosion. Deux plantes, Gueftarda et Portulaca, qui etaient maladives a dix mois, se sent ameliorees au seizi&me mois. Des photographies de la restauration de plusieurs de ces plantes sent inclues clans ce rapport ainsi qu’une discussion des agents autres que Ies radiations connus comme etant cause de semblables d~gats aux plantes des attok de der Jahre 1954-57 durchgefuhrt urn die Geschwindigkeit der Erholung der durch Bestrahlung, Schock und Hitzestoss der Nectar Detonation in 1954 beschiidigten Landpflanzen festzustellen. Auf der Belle Insel wurden sieben Arten vor der Detonation markiert, gemessen und photographiert. In ungefahr monatlichen Abstanden, wahrend der ersten 10 Monate nach der Detonation und danach nach 6 Monaten wurden die Pffanzen wieder beobachtet und photographiert. Das erste Anzeichen der Erholung wurde am achten Tag gefunden, indem Knospen an den Stammen von Scaevola und Messerschmidia jft’arrzen sichtbar wurden. Xach e’ncm Monat hatten die meisten Pfianzen neue Blatter gebildet und einige hatten Bluten und Fruchte. Nach 6 kfonaten war der generelle Zustand der Vegetation iihnlich dem der vor am Detona- *Operated by the Univemity Atomic Energy Commission. of Washington under Contract No. AT(45–1 ) 1385 with the United States

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tion existierte. Zwei Pflanzen, Guettarda und Portulaca, die nach 10 Monaten noch ungesund waren, batten sich nach 16 Monaten gebessert. photographien einiger der erholten pflanzen sind diesem Bericht beigef%t, sowie eine Besprechung der Mittel, ausser den Strahlungen, von denen iihnlicher Schaden wir der an den Pflanzen der Korallenattolle des Pazifik berichtet INTRODUCTION to many months. The results of the investigaSINCE the summer of 1946, the Laboratory of tions conducted in 1946,[7) 1947,[1) 1948,(2) [<adiation Biology of the University of Washing- 1949,(3} and 1952(S) indicated the need for a ton has conducted studies at the Eniwetok study of the reinvasion or regrowth of organisms Proving Ground to evaluate the distribution of in an area contaminated by radiation. radioactivity in aquatic and terrestrial organisms A study of this nature was undertaken of the atolls of the western Pacific and adjacent following the detonation of an atomic device areas. These studies were made either shortly (Nectar) at Eniwetok Atoll in the spring of 1954. after a nuclear device had been detonated or Facilities were made available at the Eniwetok after intervening periods varying from several Marine Biological Laboratory on Elmer (Parry) Nec tor site FIG. i. Eniwetok Atoll.

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184 RECOVERY OF THE LAND PLANTS AT ENIWETOK ATOLL Island by the Division of BIoIogy and Medicine of the United States Atomic Energy Complants also were observed. Before the Nec detonation the plants were staked, labell measured and photographed. After the dem tion, and at approximately monthly inter-i thereafter, observations and measurements w made of the plants and photographs were tak Scaevola sericea Vahl, a woody shrub, was cho, as the principal plant for study because of widespread occurrence on the islands of [ Central Pacific Ocean. The other plants studi speciosa and Cocos nuct~era, trees; Lepturus repe a grass; Boerhaavia tetrandra and Triumf~ procumbent, prostrate vines; and Portulaca olerac a fleshy herb. The locations of these plants the island are shown in Fig. 2. Gamma survey-meter readings also were tak to determine the gamma dose to which t! plants were subjected. mission, and logistic support to carry out the sampling programme was furnished by Joint Task Force Seven of Operation Castle. The study of the land plants was a part of the Over-all mogramme of the Laboratory of Radia-.W tion Biology. In this report only the results of this portion of the programme are presented. The results of the investigations on the following organisms already have been reported: reef “The objective of the land plant programme was to determine the length of time required for a plant damaged by a nuclear detonation .,,, to resume its normal functions of growth and reproduction while being subjected to chronic The main site of study was Belle Island tion (Fig. 1). This area was estimated to be far Belle Island during the period of investigati[, are given in Fig. 3, which includes the theoretic. gamma dose rate according to MILLER an LOEB.(lEJThe accumulated total dose from or. minute after the detonation to the end of 20 days was calculated to be approximately 400: Before the Nectar detonation, the plants o Belle Island were generally green and health] ,. enou.~h removed from qround zero that the plant; would not be upro~ted by physical forces yet would be in an area of sufficient radioactivity for the proposed study. Representative plants of the eight most common species growing in the area were., 3 studied in detail; however, numerous other Secward reef flat FIG. 2. Diagram of Belle Island, Eniwetok Atoll, showing the location of the land plant .. .,. stations and the collecting areas. Guettarda speciosa 1207 Boerhaab,ia tetrandra Lepturus repens 1211 Portulaca o[eracea

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med. Before the lNectaj s were staked, labelled aphed. After the detona. nately monthly intervals Jand measurements were photographs were taken. wood y shrub, was chosen for study because of its on the islands of the The other plants studied hmidia argentea, Guettarda ‘a, trees; Lepturus repem, trandra and Triumfetta tions of these plants on readings also were taken la dose to which the eter readings taken at nclttdes the theoretical iing to MILLER and ~ d total dose from one ! m to the end of 200 ~ lation, the plants on ~ FIG. -1. General ,,iew of land plants at Belle Island, Eni\vetok Atoll. (a) On .\pril 15, 1954,.- before the Nectar detonation. (b) On May 22, 1954, eight days following Nectar, showing a ScaeLo/a plant (iNo. 13 19) in the foreground.

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FIG. 5. Messemchmidia plant at Belle Island, Eniwetok .Atoll. (a) Plant No. 1248 showing adventitious buds on lMay 22, 1954. (b) Close-up of the same plant on June 18, 1954.

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FIG. 6. Land plants at Belle Island, Eniwetok Atoll , Area D. (a) Three months after the Nectar detonation. (b) Six months after detonation.

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FIG. 7. Guettarda plant at Belle Island. Eniwetok Atoll. (a) Close-up of unhealthy plant

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FIG. 3. Gamma dose rates ,at three feet at Belle Island, Eniwetok Atoll, May 15, 1954 to ,March 21, 1955, compared with the decay of fission products from the slow neutron looking. A photograph of the general area taken ance of the vegetation. In some plants there was yellowing of the leaves and necrosis, especially in Scaevola and Guettarda, and some reddening of the tops of the grass, Lepturus repert-s.The latter symptom is typical of some species of plants growing in phosphorus-deficient soil, a condition often found on coral atolls and in areas where the top soil has been disturbed or blown away. The Mike detonation of 1952 had removed most of the plants and top soil from Belle Island, resulting in the depletion of some of the elements essential for plant growth. In spite of these deficiencies regrowth of the plants at Belle Island was rapid. In April 1954 some of the Scaevida and A4esserxchrnidia “trees” were Up to five feet in height, with a spread of ten feet, and bore many flowers and fruits. Plants of the other species also were well established. A photograph of Belle Island taken eight days following the Nectar detonation (Fig, 4b) shows the extent of the damage sustained by the plants. From the air the island looked brown and desolate. On closer inspection it was found that most of the plants had been scorched by the heat wave and many of them had been blown over or broken by the shock bIast. Two of the previously tagged plants (Cocos and Portulaca) had disappeared or had been dislodged from their ori~inal positions; other plants of these species were staked and labelled for study. On the tal [ shrubs, such as Scaevola, Messerschmidia and Guettarda, the leaves were usually gone or scorched, and the scorched branches and a few persistent leaves were all that remained of the plants. Flowers and fruits were found on some plants, especially in the prostrate plants such as Portulaca, which was located behind a large fallen coconut trunk. close-ups of examples of damaged plants eight days post Nectar are shown in the foreground of Figures 4b and 5a. Recovery of the plants was rapid. Heavy rains occurred on the third day. on the eighth

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186 RECOVERY OF THE LA%’D PLANTS AT ENIWETOK .ATOLL the shoot leaves were 7–1 5 cm long, covering much of the old stems (Fig. 5b) and giving the plants a green and healthy appearance. By this time many of the other plants had formed new leaves and three species (Portulaca, Triumfetta, and .~~esserschmidia) had produced new flowers and fruits. The island now had lost its scorched appearance; from the air it looked green rather than brown as it had one month earlier. In August, three months after the detonation, the plants were growing well (Fig. 6a) and some species, such as Boerhaavia, had produced new flowers. The leaves of most of the species had grown to maximum size, and the branches had grown almost to the pre-Nectar dimensions. This was not the case with the Gue~tarda and Lepturus plants, which recovered more slowly than the other species. The new growth on the Guettarda plant consisted of ten small leaves which originated from a new shoot 18 cm tall at the base of the old plant; the Lepturus plant was’ a mat of dead tops with some new growth forming at the periphery. In six months the general condition of the vegetation (Fig. 6b) was similar to that which existed before the Nectar detonation. In March 1955, approximately ten months post Nectar, the plants appeared to be normal, most of them bearing abundant flowers and fruits, healthy, green leaves, and the usual amount of yellow, older leaves. The Guettarda plant, however, bore curled, distorted, and unhealthy-looking leaves (Fig. 7a). When observed again in November 1955, it bore about thirty healthy, green leaves, had increased in height and apparently was plant bore only a few leaves in March 1955, but when observed in November 1955, it had recovered somewhat, bearing abundant flowers and some green leaves. No other aberrant growth forms were seen in the field observations at Belle Island. At Janet Island, the fasciated stems and the tumorous growths on plants of Ipornoea /uba -- observed in 1949 by BIDDULPH(@ were still The measurements and observations made on one of the plants, Scaevola (No. 13 19), during the course of the study are presented in Table 1. Previous studies to evaluate the recovery ar reinvasion of the flora at the Eniwetok Provir Ground, approximately fifteen months aft{ Operation Sandstone, were made in 1949 [ morphological abnormalities in ten species t plants growing on islands where atomic detona tions had taken place, and where radiatio: levels were undoubtedly higher than those o] Belle Island during the Nectar survey. Thes, abnormalities included flattening, shortening thickening and spiral torsion of stems, severt “die-back” of leaves and stems, chlorosis asymmetry, shriveling, crumpling and twistin~ of leaves, chromatism of stems, proliferation anc enlargement of inflorescences, abnormal proliferation of stems, and sterility of plants. St. John reported finding a mutant of Guettarda speciosa on Runit Island but did not describe it. Biddulph reported spiraling and splitting of fronds on several coconut palms on Aitsu (Olive) Island, which is located between two of the On the “shot” islands, the plants closest to the bomb crater centres (where radiation levels were highest) were most severely affected. In areas where radiation levels were lower, the ported to be more important in excluding plants from these areas than the radiation effects from the bombs.(c) Undoubtedly many of the abnormal plants started their growth after the nuclear detonations had occurred in impoverished soil lacking inorganic nutrients and organic matter. These conditions are known to cause nutrient deficiencies which can sometimes be identified by the appearance of the plant. In coral atolls where the top soil has been removed the retention of rain water in the surface layer of soil would be slight, resulting in the curling, drying, and ultimate death of the shallow-rooted plants. On the basis of these observations it may be concluded that some of the abnormalities observed could have been caused by factors other than radiation. Therefore, it would be impossible to ascertain all of the causes of damage to plants in an area where radiation and nutrient deficiencies both exist. In areas of high radiation levels, much of this damage

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altrate the recovery ar t the Eniwetok Provin fifteen months aftc ‘ities in ten species c j where atomic detona and where radiatiol higher than those or ‘sion of stems, severe mutant of Guettarda t did not describe it. ng and splitting of xfween two ‘of the he plants closest to Is were lower, the ‘Y many of the r growth after the ions are known to ich can sometimes ~e of the plant. In has been removed the surface layer lg in the curling, Lused by fhctors re, it would be f the causes of xist. In areas of …