ATOLL RESEARCH BDLLETIN
- -
No. 29
A
Summary of Information on Roae A t o l l byM.-H. Sachet
Issued by
THE PACIFIC SCIENCE BOARD
National Academy of Sciences-National Research Council Washington, D. C.
A sumnary of information on Rose A t o l l g a r i e - ~ 6 l e n e Sachet
b,Y
Rose A t c )11, t h e easternmost of t h e Samoa I s l a n d s , i s one of t h e smallest a t o l l s known and i s of s p e c i a l i n t e r e s t , because it has hardly been influenced by man, Its s i t u a t i o n n o t t o o f a r from t h e s e t t l e d
islands of t h e group, t h e f a c t t h a t it i s generally easy t o e n t e r t h e lagoon and land on t h e i s l e t s , and various other circumstances have made it one of t h e b e t t e r known uninhabited a t o l l s , The l i t e r a t u r e con-
oeming it has been brought t o g e t h e r by S e t c h e l l (1924) and by Bryan (1942). This paper i s not intended t o replace t h e s e contributions
but t o summarize a l l a v a i l a b l e information on land a s p e c t s of t h e a t o l l . It n e c e s s a r i l y repeats muah information contained in these e a r l i e r oompilations but may thus be h e l p f u l t o those students of a t o l l s t o whom these a r e not e a s i l y available. I n addition t o published accounts,
it includes notes based on l e t t e r s of Mr. E. H. Bryan, Jr. and on conversations with D r . L. P. Schultz and data obtained from t h e i r photographs and unpublished records. Their valuable h e l p i s grate- f u l l y acknowledged.,
Geography
Rose A t o l l i s located between 14O31' and 14'341 S and between 1680081 and 168O10 W. I t i s a very small a t o l l , roughly square
i n
o u t l i n e and about 1 3/4 m i l e s from north t o south and 2 miles from e a s t t o west. J u s t west of the north point, o r c o m e r of t h e square,i s
t h e only channel i n t o t h e lagoon. The channel i s 100-150 f e e t wide and of variously reported depth: 6 fathoms o r more (Rantzau i n Graeffe, 1873), 30 o r 40 f e e t (Anon., 1953) with records of 6 t o 9 f e e t , o r 6 f e e t o r more t h a t a r e probably erroneous o r r e f e r t o t h e p a r t of t h e channel t h a t i s choked with coralt Bryan (1942) reported t h e channel p a r t l y blocked with ooral heads on t h e west side. The lagoon is about 2000 yards across i t s g r e a t e s t width, and i t s depth i s variously estimated a s 6 t o 12 fathoms (Wilkes, 1845), n o t more than 8 fathoms (aayor, 1924) o r up t o 50 f e e t (Bryan, 1942). The f l o o r of t h e lagoon i s sandy, and generally f r e e of l i v i n g c o r a l s (Couthouy, 1942, p. 138). But some c o r a l s do grow in it, Wilkes described one such formation: " l i k e asubmerged t r e e , t h i r t y f e e t i n diameter over i t s t o p [ i t l , v r a s found in t h e center of the lagoon r i s i n g t o t h e l e v e l of low water and having a l l around it a depth of s i x fathoms," This may be p a r t of t h e two o o r a l patches mentioned by Rantzau (Graeffe, 1873) a s ocourring
in
t h e southwest corner of the lagoon and indicated on h i s and l a t e r maps.The reef i s remarkably uniform in width, about 500 yards every- where, with a very f l a t surfaoe, most of which i s under water even a t
l o w t i d e , though some areas emerge a s smooth platforms about a foot above low t i d e . There i s very l i t t l e loose material on t h e reef. I t supports only two i s l e t s , Sand I s l e t , t o t h e north, near t h e entrance
49 t o t h e lagoon, i s a bank of sand and broken reef material, devoid of vegetation and about 5 f e e t above sea l e v e l + Although t h e chart8 a r e not e n t i r e l y r e l i a b l e , t h e r e i s some indication t h a t t h e i s l e t has been
d*
l a r g e r (see discussion of Rantzaufs o h a r t , (pp.
4 - 5
).Sand I s l e t i s q u i t e possibly v a r i a b l e in area, e s p e c i a l l y a s no p l a n t s a r e present t h a t a r e capable of colonizing and f i x i n g i t s s o i l . I n 1936
i t s dimensions were estimated a s 200 yards in length and 50 yards i n width (Bryan, 1942). I t l i e s on t h e lagoon s i d e and has a wide expanse
of reef on i t s seaward side.
A t ' t h e e,astex% corner of t h e square i s Rose Island, which i s l a r g e r than S a n d : I s l e t . Mayor, in 1920, gave t h e length a s 240 yards along a north t o n o r t h e a s t d i r e c t i o n and t h e width a s 200 yards. Bryan, i n 1938, e s t i m a t e d t h e i s l a n d 350 yards long ahd 250 yards wide. Schultz (1943, p. 3) s a y s ' t h a t i n 1939 it seemed t o be building up on t h e northwest and being eroded on t h e south end. This agrees with some notes by Mayor - - . and Bryan. Rose I s l e t has a g r e a t e r e l e i r a t i o n than Sand I s l e t , reaching 11 f e e t above high t i d e a l i t t l e inland of t h e southeast corner (Nayor, 1924,
g.
74). It i s higher in the'south than a t the northern end and, l i k e Sand I s l e t , it i s l o c a t e a on t h e lagoon h a l f .of t h e reef; . .. . . . .
: . , . ,
History . . ,
. .
. . .
.
. . . . .Rose Atoll' was discovered on October 21, 1819, from t h e s h i p s - . 1'Uranie and l a Physicienne, and was named Rose Island .by t h e commander of the expedition, Louis de Freycinet "for a person extremely dear t o me." The s h i p s did n o t e n t e r t h e lagoon o r come very close t o t h e island.
However, Freycinet described t h e island a s observed from t h e sea, and Duperrey drew a c h a r t t h a t i s included in the a t l a s of t h e expedition reports. I n h i s volume on navigationn andhydrogr6phy (1826, p. 8 5 ) . Freycinee gave.information o n t h e weather, o n - t h e animals observed off t h d , a t o l . l , o n t h e l o n g i t u d e , and o n t h e l a t i t u d e estimated a t noon.
He-described h i s discovery. (1826, p. 250) marveling a t t h e f a c t t h a t . . t h e - a t o l l had n o t been observed and aharted e a r l i e r . He mentioned only
. .
.
. .R o s < I s l e t , but he said of
it:
.,. . .., . . . . . . . . .
. .
" I t s height generally mediocre, i s g r e a t e r in t h e 5W;
' t h e land gradually slopes down toward t h e NE where
it
. . merges with t h e sand of t h e shore,.
. .
. . , , . . .
. . .
.. . <. "Although very small, t h i s i s l a n d i s well wooded, which
gives it a very pleasant look of freshness. Various sea b i r d s seem t o b e t h e only M a b i t a n t s of t h i s l o n e l y place; we p a r t i c u l a r l y noticed f r i at;e.birds, boobies,
. tropic-birds, noddies, and t e r n s fa*parently two small s p e c i e g . . Among the t r e e s , t h e r e a r e no oooonut t r e e s nor any other.kind of,palms.
"The whole island, a s we-have said, i s surrounded by a bank j u s t below water l e v e l , grossly t r i a n g u l a r , of mixed
sand and madrepores; it i s b r i s t l i n g with m a l l black rocks, not very much r a i s e d above i t s surface, and a l l of about,
.
. .t h e same height. One of t h e angles of t h e bank i s t o t h e . .
: SW, another t o t h e E, and t h e t h i r d t o t h e N: i t s dimen- s i o n s a r e 3 m i l e s [ne.ut3.c@ from N t o S, and a l i t t l e l e s s from E t o W. The sea branko .much a l l around, and t h e surge can be f e l t from one o r t w o o ~ h l e lengths a t
sea: we followed i t s e a s t e r n p a r t a t a dis%noa of-nnn
and a h a l f m i l e l g , without seeing bottom under us.
. .
. . '%.i%en one staads t o t h e
N
of Rose Island, it shows a semi-circular sha e; seen from the E it looks l i k e . . . 9 'coin de mire1 8 s wedge-shapeg with i t s higher . . . . .p a r t
looking t o t h e south. To t h e X3, and very close. . .
,,:
~. [t.o t h e i s l 6 t ; g a l i t t l e black rook, a regular cone,.
. p s e s above a l l t h e rocky heads j u s t mentioned."
.. Tiiis ' l i t e r a l t r a n s l a t i o n shows t h a t Freycinet observed t h e i s l e t a r i d r e e f e x a a t l y , which makes it a l l t h e more d i f f i c u l t t o understand some, asp?ots of Duperreyss ohart, namely, t h e two areas' that. S e t p h e l l intei-preted a s two a d d i t i o n a l sandy i s l e t s . Although Freycinet did n o t mention' any sandy " i s l e t " , h i s d r a w h g of t h e l a n d f a l l , presumably made from about e a s t t o southeast, showed on e i t h e r s i d e of t h e wooded i s l e t
some l i t t l e black rocks and a broad mound. These may be sand banks and correspond. t o t h e patches of the c h a r t . Freycinet's d e s c r i p t i o n of t h e i s l e t i s det,ailed enough f o r us t o believe t h a t t h e t r e e s may have formed two groves, a large one ' t o t h e southwest and a t i n y one t o t h e northeast, which apparently does n o t e x i s t any more. .~&fnortheast .grove e i t h e r
joined th.6 other one or was destroyed by a change in the shape of t h e i s l e t , ' Freycinet; described Rose again l a t e r in h i s h i s t o r i c a l account .
of the v o y a ~ e . > . . .
The Russiap expedition of t h e , p r e d p r i a t ie ( ~ n t e r ~ r i s e ' ) , commanded by 0. de Kotzebue, passed a l i t t l e c o r a l island on April 2, 1824, and named it Kordinkoff (Kotzebue, 1830, p. 256), l a t e r t o r e a l i z e t h a t it was t h e same a s Rose, Kotzebue's sketch of t h e a t o l l i s not much b e t t e r than Duperrey1s, although it show? a closed lagoon.
On September 23, 1838, Dumont d l U r v i l l e , on another French
expedition, passed Hose I s l a n d following t h e reef a t a distance of l e s s than a f i a u t i c a g mile and gave a b r i e f description of it (1842, pp. 91- 92) :
"Rose Island i s but a p i l e of sand about 200 m.
i n diameter, covered with a grove of verdure very f r e s h looking and pleasant.
"Passing about 600 m. t o t h e north of t h e reef edge, we saw in t h e reef a break. about 100 m. wide, leading
i n t o t h e lagoon where the' water seems r a t h e r deep, and
'
w h i c h ought t o be able t o o f f e r s h e l t e r t o s h i p s a s small a s ours."
The ~ r e n c h expeditions were s c i e n t i f i c i n p r p o s e , and t h e i r 3pstruotions placed much emphasis on obtaining p5ysical, n a u t i c a l , and meteorological information. The discovery and surveying of new l a n d s ' was reoomymded also, but these lands vrere e s p e c i a l l y worth i n v e s t i g a t i n g
i f they could bring new people and t h e i r customs, new plants, new animals, t o t h e n o t i c e of Science. The f a c t t h a t low islands present danger and d i f f i c u l t y i n landing, e s p e c i a l l y with a s a i l i n g vessel, a s well a s t h e i r .recognized p a u a i t y in s c i e n t i f i p n o v e l t i e s , r e s u l t e d i n a general avoidance of a t o l l s by most e a r l y expeditions, including t h e Fremh.
The U. S . .Exploring. Expedit.i,on was. d i f f e r e n t i n scope and aims, and without neglecting s c i e n t i f i c di&overy, v i s i t e d many of these a t o l l s , reputedly a l l a l i k e , f o r the purpose of c h a r t i n g them. It w a s much l a r g e r than any of the previous expeditions both in ships and in naval and s a i e n t i f i c personnel. I n s p i t e o f . i t s v e s s e l s and t h e un- ending arguing, prosecuting and f a n t a s t i o mishandling of t h e r e s u l t s which followed it, t h e expeditionwas generally remarkably successful,
and, althdugh some of the
information
has never been published, it brought back vast amounts o f data, c h a r t s , s a i e n t i f i 0 c o l l e c t i o n s , and drawings. I t was t h e f i r s t "Atoll Program", and a f t e r surveyingmany of t.he Tuamotus, one of the ships, t h e Vincennes a r r i v e d a t Rose Atoll, on Ootober.7, 1839. A p a r t of the day was spent in observations, and Wilkes (1845, p. 64) in t h e n a r r a t i v e of t h e voyage gave an account ofthem, but t h e b e s t d e s c r i p t i o n published, and t h e only one of an eye- witness, i's t h a t of Piokering (1876, pp. 235-2361:
, . . . . 1'14. ROSE CORALISLAND. As t h e Vinceqnes drew
. . . .,. . . .
. . . near, t h e supposed rock proved t o be a dense clump of
. . . t r e e s upon a miill coral-island; 'in S. Lat. 14°18' and
W. long. 168°05f, and about e i g h t y miles' from. t h e n e a r e s t rocky island of t h e Samoan Group. Rose' coral- . . island, though hardly 'two miles' in diameter, was found
t o contain a lagoon; having a l a r g e o u t l e t deep enough t o admit a ship, and ' s i x fathoms' inside, exaept a t t h e c e n t r e of t h e lagoon, where a c c l u q of coral-rock r i s e s t o within ' t h r e e f e e t * 'of the surface, The t i d e r i s i n g 'about f i v e feet',, most of t h e i s l a n d i s sub-
. merged a t highwater; b u t . t h e o u t l i h e 'continues d i s - tinguishable by t h e l i n e of surf, with here and t h e r e a p r o j e c t i n g massive coral-block; a t a l l times, we found much water beating over from t h e windward, and
. ,running in streams i n t o the lagoon,' and afterwards in
''
. a strong c u r r e n t through t h e o u t l e t .
. . . .. . . , .
"Two banks on t h e rim were never overflowed by t h e t i d e ; one of them devoid of vegetable growth; t h e other, containing t h e above-mentioned dense grove of t r e e s , found t o be t h r e e o r f o u r a c r e s in extent."
Dana (1849, p. 78, 308) a l s o discussed Rose Atoll, but unfortunately he did n o t see it, a s he was t r a v e l i n g i n another of t h e ships. Couthouy, however, was s t i l l on the Vinoennee (he was going t o abandon t h e Expedi- t i o n shortly, in Samoa), and presumably landed on Rose. P a r t s of h i s
account (1842) seem d i f f e r e n t from what was reported by Wilkes, Pickering, and Dana, and h i s account has been termed "somewhat f a n c i f u l " (Setchell, 1924): but he d i d give some information on t h e entrance and lagoon. He noted (p. 99) t h a t t h e entrance i s t o leeward, a s i s o f t e n t h e case on
a t o l l s , and water pours out of it a t ebb t i d e "so a s t o resemble a m i l l race. "
The next recorded v i s i t was t h a t of Captain Rantzau (Graeffe, 1873, p. 32), who v i s i t e d t h e a t o l l a t various times while a German f i r m was t r y i n g t o e s t a b l i s h a f i s h i n g s t a t i o n there. He transmitted some valuable
information t o Graeffe and drew a sketch of t h e a t o l l , on which Sand I s l e t
*/*
i s represented a s large and extending f a r i n t o t h e lagoon and Rose I s l e t a s covering t h e whole width of t h e reef and supporting a house and t r e e s . During these times coconut t r e e s were planted and reported t o do well and t o bear f r u i t . The i s l a n d was s e t t l e d f o r a while by an Englishman and a few natives. Later one native alone remained with h i s family, and then t h e island was f i n a l l y restored t o i t s loneliness. Rantzau's sketoh, together with exoerpts from Graeffels t e x t , was reproduced i n t h e f i r s t volume of t h e Hydrographische Mittheilungen ( l a t e r Annalen der Hydro- graphie..
.
) p. 64, 1873, His o u t l i n e of t h e reef may have been based on some e a r l i e r chart, but h i s sketuh was apparently used a t l a t e r d a t e s by the Hydrographic Offices of England and t h e United States.I n 1899, a f t e r muah tension and p o l i t i c a l d i f f i c u l t y , Eastern Samoa became an American t e r r i t o r y . The f i r s t governor, B. F. T i l l e y , v i s i t e d Rose A t o l l on J u l y 10, 1900, h o i s t e d the American f l a g "with appropriate ceremonies," and planted coconuts. I n January 1920, Governor W. J. Terhune v i s i t e d t h e Manu'a d i s t r i c t , and on January 12 landed on Rose A t o l l , erected a s i g n t o warn t r e s p a s s e r s , and planted a 'variety of f r u i t t r e e s , including ooconuts. H i s stop a t Rose was reported
in
t h e monthly government newspaper 0 Le Fa'atonu, i n t h e i s s u e f o r February 1920 (Dumstrey, 1920). I n June 1920, he returned t h e r e and was accompanied by t h e marine b i o l o g i s t A. G. Mayor who was working i nSamoa. The J u l y issue of 0 Le Fa'atonu gave a short but informative account of t h e v i s i t and mentioned the value of the information c o l l e c t e d by t h e distinguished s c i e n t i s t . More coconuts were planted, including two on Sand I s l e t . The i n v i t a t i o n extended by Governor Terhune t o A. G.
Mayor r e s u l t e d in valuable observations t h a t a r e t h e most important body of information on Rose A t o l l and a r e desoribed i n other p a r t s of t h i s paper.
There were yearly governor's v i s i t s t o t h e a t o l l a f t e r t h i s and more p l a n t i n g s of ooconuts. I n 1922, Governor Pollock found t h a t
Governor Terhunefs ooconuts had disappeared, so he planted some more. He a l s o c o l l e c t e d s o i l samples f o r Lipman.
Wray Harris now conohologist a t t h e B.
P,
Bishop >5useum, made a t l e a s t tvfo v i s i t s t o Rose i n 1937 and 1938 and c o l l e c t e d mollusks and a few p l a n t s.
In 1938 the U. S. Coast Guard c u t t e r Taney v i s i t e d t h e Equatorial Islands and landed a p a r t y of s c i e n t i s t s on Rose A t o l l on August 4, f o r an hour. E, H. Bryan wrote accounts of h i s observations (1939 and 1942, pp. 91-93), and much of our knowledge of Rose A t o l l i s derived from them. W. Donaggho (1953, p. 68), a s s i s t a n t t o G. C. Munro, wrote
some notes on t h e b i r d s observed.
I n 1939 t h e U, S. S. Bushnell made a survey of islands i n t h e c e n t r a l Pacif i c , and D r . L.
P.
Sohultz, of t h e U. S. Iiational Museum,spent 11 days c o l l e c t i n g f i s h around Rose A t o l l and in the lagoon (June 11-
On February 14, 1941, Rose A t o l l was made a Naval Defense Sea Area by an Exeoutive Order of President F + D. Roosevelt.
This order was resoinded by Executive Order 10,341 signed by President Truman on April 8, 1952. E a r l i e r ( J u l y 1, 1951) the Samoan
*/*
Islands had come under t h e j u r i s d l . c t i o n of t h e Office of T e r r i t o r i e s in t h e Department of t h e I n t . e r i o r . I n February 1953 a f i s h i n g survey .was conducted near Rose A t o l l , and some. informat ion on .the island:. was published
i n t h e Weekly News B u l l e t i n on February 21, 1953. Excerpts .from Ohis b u l l e t i n were received through' t h e kindness of Mr. E m i l Sady, chief of t h e P a c i f i c Division, Office of T e r r i t o r i e s . This i s t h e l a t e s t informa- t i o n a v a i l a b l e on Rose, and it brings up t o date o u r knowledge of t h i s 1 i t t l e a t o l l .
Meteorology
There a r e no meteorological records whatsoever from Rose Atoll.
Even t h e visitora.whose accounts a r e used here gave'almost no information on t h e w e a t h a t a t the time of kheir stays, except f o r t h e weather a t sea described by Freycinet. The o n l y source of data t h a t gives an idea of meteorologia ccnditions in the region i s the Weather summary f o r Naval Air:Pklot, H. 0. 272 of t h e U . S. Hydrographic Office, which i s used throughout t h i s section, without f u r t h e r acknowledgment. I t o f f e r s in- formation t h a t can be used in g e t t i n g an i d e a . o f weather and climaCe a t Rose I s l a n d and i s compiled from ships' observat2ons, mapped and tabulated f o r 5-degree ocean areas, t o g e t h e r w i t h general t r e n d s a s expressed by
isobar o r isotherm charts. The island n e a r e s t t o Rose Atoll. from which ace available data t h a t cannot be collected by ships' observations (such a s temperature v a r i a t i o n and t o t a l r a i n f a l 1 ) ' i . s Tutuila. But t h i s is' a.
high island, and i t s weather s t a t i o n a t Pago Pago i s d o ~ i n a t e d by a mountain c a l l e d t h e "Rainmaker", because it p r e c i p i t a t e s moisture f r o n every cloud passing over it. The a t o l l n e a r e s t t o Rose some weather data i s Puka-Puka (Danger I s l a n d ) . It i s i n t h e same 5-degree square a s Rose but in the n o r t h e a s t corner ( 1 0 ~ 5 3 ' 5 , 165O54' W.) The records avail%xble'since 1929 a r e stntimarize'd in a note. by t h e New Zealand
Meteorological ,Off ice (Seelye, 1943):and i n t h e Great B r i t a i n P a c i f i c I s l a n d s P i l o t (,v. 3, 1946); Both o f t h e s e p u b l i c a t i o n s a l s o o f f e r some
information on weather and climate a t . A i t u t a k i , t h e . o t h e r weather s t a t i o n n e a r e s t t o Rose Atoll, although much t o t h e southeast. This i s a high
island ( 4 6 0 . f e e t ) on an a t o l l - l i k e reef. The observations a r e made on t h e west side of the,main i s l a n d (18°52!30''VJ.). at an a l t i t u d e of 10 ' f e e t . Rather than use data from t h e high Samoan I s l a n d s or Niue, those from
Puka-Puka and Aitutaki are occasionally mentioned, because they can a t l e a s t g l v e an. idea of t h e order of magnitude of c o n d i t i o n s on Rose. Atoll,
. ,
. . , . . . . .
Atmospheric pressure: The 1008-millibar isobar f o r January passes j u s t north o f R o s e A t o l l and j u s t south of Puka-Puka; the 1012-millibar isobar f o r J u l y passes n e a r t h e location :of Rose, whereas t h e 1010- m i l l i b a r isobar f o r J u l y passes close t o Puka-Puka. (Great B r i t a i n ' .
P a c i f i c Islands P i l o t , v. 2, pp. 18-19). These f i g u r e s probably express t h e range of v a r i a t i o n a t Rose Atoll, except, of course, f o r depressions
accompanying possible hurricanes.
Tropical cyclones and hurricanes: No cyclones and hurricanes a r e reported from Rose Atoll, but among the Samoa Islands, years may pass without a destructive storm, though two o r t h r e e cycloneshave been
known t o occur in a s i n g l e year, with January.and March asmonths of highest frequency. The most famous hurricane in Samoan h i s t o r y i s t h a t of M a r c h l 3 t o 23, 1899, which; occurring at. a moment of g r e a t i n t e r - n a t i o n a l tension, kept e v e r y o m so busy, t h a t . p o l i t i c a l i s s u e s became
a / *
secondary and were solved more amicably than they might otherwise have been. The t r a c k of t h i s hurricane (Chart 23, H.O. 272) does not pass near Rose Atoll, nor do any other t r a c k s of t h e few cyclones p l o t t e d on t h i s chart. East of Rose Atoll, hurricanes have been known t o occur and cause much damage, a t Puka-Tuka, Nassau, and e s p e c i a l l y a t Swiarov, but they are r a r e ,
' Prevailing winds a t sea: Rose I s l a n d l i e s in the region where t h e n o r t h e a s t e r l y t r a d e winds penetrate t h e south l a t i t u d e s : I n t h e 5-degree
square j u s t n o r t h and west of t h a t of Rose (5' t o
lo0
S,, 170' t o 175'w.),
surrounding t h e Union group, 29 percent of the annual winds a r e from t h e northeast, 32 peroent from t h e e a s t , and only 1 3 peroent from t h e south- east. A t about t h e
l o 0
S, the southeast t r a d e winds d e f i n i t e l y become more frequent; and in 10' t o 15' S, 166' t o 170° W. (Rose Atoll square)southeast winds a r e recarded a s 25 peroent of t h e annual winds, north- e a s t t r a d e s a s 1 7 pereent, and e a s t winds, the most frequent, a s 34 percent (see t a b l e p.
9).
Ocean gales, s q u a l l s and thunderstorms: Rose A t o l l l i e s i n an a r e a where both gales and s q u a l l s a r e r a t h e r common, being reported in 14 per-
cent of the ships' weather observations. Thwderstoms a r e reported in 4 peroent of t h e ships' observations. A l l t h e f i g u r e s f o r gales, squalls, and thunderstorms a r e much l e s s f o r t h e 5-degree square of Rose A t o l l than f o r t h e next one west, where the high Samoan I s l a n d s a r e situated.
Sea temperature: Rose A t o l l l i e s in a region between t h e two 82' F isotherms f o r sea temperature (north and south of t h e
qua tor)
f o r February(southern summer), and the 80° F isotherm f o r sea temperature (Southern Hemisphere) f o r August passes j u s t north of Rose (Great B r i t a i n P a c i f i c Islands P i l o t , v. 2, pp., 18-19). These f i g u r e s probably express t h e range of yearly v a r i a t i o n of sea temperature a t Rose, A t Puka-Puka t h e v a r i a t i o n i s reported a s from 81° t o 83' F (Seeley, 1943).
A i r temperature: There a r e no f i g u r e s a t a l l f o r a i r temperature a t Rose I s l a n d or t h e ocean around it. A t Puka-Puka t h e mean f o r t h e year i s 82.2O F, with very s l i g h t v a r i a t i o n from month t o month
(83.1' f o r May, warmest month; 81,8O F f o r January, coolest month).
The averages of t h e annual extremes a r e 93' F and 71° F, and t h e absolute extremes a r e 97O F and 70° F. A t A i t u t a k i t h e Southern Hemi- sphere seasons a r e well marked; t h e warmest months a r e January and
February (81,0° F mean temperature), and t h e c o o l e s t i s August (75.4' F).
The yearly mean i s 78.2 0 F. A t Rose Island t h e southern seasons a r e probably s l i g h t l y f e l t , whereas Puka-Puka s t i l l has Northern Iiemisphere seasons. Rose probably has a r a t h e r even yearly temperature, of about 81° F, t h e extremes n o t reaching much above 90° F o r below 70' F.
Clouds and v i s i b i l i t y : T a b l e p.8 i s made from Charts 13 t o 1 7 of H.0, 272, f o r t h e 5-degree square of Rose Atoll. The t o t a l of ships' weather observakions f o r t h i s square i s 760 f o r t h e period 1879-1933.
Feb. May J u l y Oct. Dec.
78 49 74 63 63 Figures express percent of observa-
t i o n s recording lower type clouds.*
3.4 5.1 4.4 9.5 6.4 Percent of observations with excep- t i o n a l v i s i b i l i t y .
1.7 1.3 1.5 0.0 1.8 Percent of observations with haze,
0.0 0.0 0.0 0.0 0.0 Percent of observations with fog.
*
Lawr type clouds a r e apparently t h e t r a d e wind cumulus and variovs r a i n clouds.Relative humidity: A t Puka-Puka t h e mean r e l a t i v e humidity f o r the year i s 79 percent, with a v a r i a t i o n of 2 percent above and below f o r t h e individual months (morning observations); t h e me? dew point ranges from 74O F in J u l y t o 78' F in April, t h e average being 76.3' F eely ye). I t may be assumed t h a t f i g u r e s f o r Rose A t c l l would be similar.
Rainfall: The evenness of r a i n f a l l i s an important f a c t o r on a t o l l s , in making t h e amount of p r e c i p i t a t i o n e f f e c t i v e . The r a i n water peroolates immediately through t h e extremely porous m a t e r i a l forming t h e islands, so t h a t t h e amount of r a i n t h a t corresponds t o extremely a r i d conditions on an a t o l l may mean much moister ones on l a r g e i s l a n d s o r continents. Gn Puka-Puka t h e r a i n f a l l i s usually heavy, the average f o r 1930-1942 being 117.57 inches a year, t h e t o t a l s ranging from 85.46 ( i n 1938) t o 155.13
( i n 1931). There i s a marked r a i n y season from November t o %larch. The average number of r a i n y days (with 0.10 inch or more r a i n ) i s 170 days per year. This i s r a t h e r low. A t Aitutaki the y e a r l y average i s 77.57
inches i n 92 days, and t h e r e i s a wet season from December t o March
(Seelye, 1943). Rose A t c l l probably has a similar r a i n f a l l , although the number of rainy days may be greater.
High s e a s : It may be of i n t e r e s t t o mention t h a t on ~uka-Pika' in . '.
February 1935 a hurricane t h a t a f f e c t e d Rarotonga brought r a t h e r high. , .
s e a s (Seelye, 194'3). The. s e a s rose on the 8th. and canoes l e f t under t r e e s 200 yards from t h e usual lcw-kide mark were n e a r l y washed awey.
Conditions were worse on t h e 9th and 10th. but t h e sea went dcvm rapidly t h e following day. This phenomenon might have a f f e c t e d Rose Atoll also.
The reef of Rose A t o l l i s almost e n t i r e l y made up of Lithothamnicn rock- a s a r e the boulders s c a t t e r e d on it. The surface of t h e a t o l l rim, where awash a t low t i d e , i s covered by vigorous growths of Porolithon t h a t form connected pink patches o r - - w e s t of t h e lagoon entrance
--
ridges 6 inches high and 6 inches t o several f e e t wide. The ridges,
*
The geology and s o i l s s e c t i o n s were prepared with much a s s i s t a n c e from F. R. Fosberg and u t i l i z e unpublished data from h i s i n v e s t i g a t i o n s i n t h e northern Marshalls in 1952.Ocean area 510 165. Position: Latitude 10' - 15'5, Longitude 165' - 170°iv.
Greenwich noon observations. Years covered 1883-1933.
-
IVind
: *
:vseather
: :--- a
Percentages
ofobservations from
2Percentages
ofobservations recording
- :. m a , : & : .-
-
:-
0. . . . .
m r i il. . . .
: " l k : 0 : :
. O g
: $ -:
: :. L > m *
a m . o : : :
. .
G O :3 :
0:s :
z5.2
:$5
: * ..
W :.
: :.
: : : ld: N ld: :d:ai-. ;z,> 2, T.,
4
rn U Z ~January : 4 5
: 1 . 1 :8 : 2 7 : 1 6 : 2 1 : 6: 5: 7: 5: 5: 0: 0:
2:0 : 1 5 : 2 0 : 9: 2:
0 : 8: 4 : 1 ; . 6
.
,February
:59
:8.9
: 11:30: 19: 5 : 2:
:4: 17:
1:2: 0: 0: 2:
8: 8:10: 5: 0
:0
:3 ~ 4 . 6 March
:57
,8 . 4 : 1 4 : 1 9 : 2 9 : 1 9 : 5: 0: 5: 7:
2: 2:0: 0: 0
1 86 7 ; 4 : 0
:2
:5 ~ 5 . 5
A p r i l :
66
:5 . 7 : 5 : . 1 9 : 3 1 : 1 5 : 7: 2: 0: 6 : 1 5 : 2 : 0 : 0: 0: 5 : . 2 : 3: 3 : 0
: O: 3 : 3 . 8 Nay : 7 8
:9 . 7 : 5 : 1 9 : 4 & : 2 7 :
1: 1:0: 0: 3:
1:0: 0 : 0: 8 ~ 1 2 : 6:
3 :0
: O: 5 : 4 . i
June
:76
: 1 :5 :
8 :54: 25: 2:
1: 1: 1:3:
I :0 : 0 :
0:4 : 12: 10: 3:
1 :3
:0 :3.6
\D I IJuly
:68
:11.6
:5: 8 : 50: 29: 6: 0 : 0 ;
1: 1: I: 1:0: 0: 9: 12: 12:
1: 1 : 0 :4
~ 4 . 8September: 66
;1 2 . 0 : 3 : 2 0 . 3 4 : 4 1 : 2 : 0 : 0 : 0: 0: 0 : 0: 0: 0: 0
1 :3 : 2 : 2
:O:.l+.7
November : 6 2
:8 . 0 : 1 0 : 1 0 : 3 5 : 2 2 : 5: 7 : 4: 7 : 0 : 3 : 0 : 0: 0 ; 5 1 1
8 :5 : O : O : 8 : 4 . 9 December
:56
:6 . 8 : 2 1 . 1 7 : 2 0 : 21: 0 : 7 : 0 : l O : 4 : 2: 0 : 0 : 0 : 6 : 4 : 5 1
0 : O: 5 : & . 8 Nean
:9.4
: 8 :17: 34: 25: 3 : 3 : 2 : 5: 3 :
1:-;'.
: +:7 .
11.9 : 4:
1 ; 1 :5 ~ 4 . 6
T o t a l
Im:
From H.O.
272,
p.62. Compiled by the L'.S.Weather Bureau -,' Less than 0.5 percent.
which a r e separated by channels, a r e occupied by other algae. The slopes of t h e reef a r e not d i f f e r e n t in t h e i r a l g a l c o n s t i t u e n t s from t h e f l a t top, except f o r the presence of some stunted Acropora and Pocillopora
( c o r a l s ) "at t h e extreme edges of t h e a t o l l rim f r o n t i n g t h e lagoon o r t h e sea." The a l g a l ridge a t the edge of t h e reef i s very weakly developed, a s a l s o a r e surge chmnels (Schulte, conversation 1953). Freycinet men- tioned small black rocks, a l l of about the same height, and t h e U. S. Ex- p l o r i n g Expedition found then t o be limestone boulders. Mayor gave them much a t t e n t i o n and wrote (1924, p. 75):
"Hundreds of l a r g e blocks of limestone l i e s c a t t e r e d over t h e f l a t , wave-washed rim of Rose Atoll. These loose boulders a r e q u i t e uniformly about 5.5 f e e t high, and only when t i l t e d a r e they any higher. I n addition t o these boulders t h e r e a r e a few others whioh a r e mush- room-shaped and s t i l l remain attached t o t h e f l o o r of t h e atoll-rim, of which indeed they form an i n t e g r a l p a r t . One of t h e most remarkable of these mushroom-
rocks l i e s t o the eastward of Rose I s l e t , and i s supported upon so slender a pedicel t h a t it would seem a s if t h e next storm must cause it t o topple over. I n many places over t h e f l a t , wave-washed f l o o r of the
a t o l l - r i m one f i n d s remnants of pedicels which once supported *mushrooms'. In addition, some of t h e
boulders have become secondarily cemented t o t h e f l o o r of the f l a t by t h e growth of Lithothamiurn around t h e i r bases. The l a r g e s t boulder we observed l a y loosely upon t h e r e e f - f l a t e a s t of Rose I s l e t and was somewhat t i l t e d by being jammed against another rock. It was 12 f e e t 5 inches long, 8 f e e t wide, and 7 f e e t 6 inches high, and a s i t s s p e o i f i c gravity was 2.3 it apparently weighs 46 tons."
He concluded t h a t t h e boulders shaved t h a t sea l e v e l must have been a t one time 6 or 8 f e e t higher than now and t h a t the s c a t t e r e d detached boulders were mushrooms t h a t had been completely undercut. He reported t h a t t h e boulders were made up cf the same algae and had generally the
same chemical composition a s t h e s o l i d reef platform, with the same high percentage of magnesium a t t r i b u t a b l e t o Porolithon.
Among these boulders, the Exploring Expedition found some s c a t t e r e d blocks of volcanic stone. They a r e mentioned byWilkes, Dana, and CouthoUy and a l s o by Pickering, who says (1876, p. 235):
"For the f i r s t time on a coral-island, t h e mineral kingdom was represented; several blocks of vesicular
l a v a being met with by our p a r t y ; i n a l l instances r e s t i n g upon t h e coral-shelf, n o t imbedded. Two o r t h r e e of these blocks were seen by myself, the l a r g e s t weighing perhaps twenty pounds. From the mineral com- position, they had e v i d e n t l y t e e n derived from some volcanic island; and t h e r e seemed no means of t r a n s - portation, unless entangled in driftwood. This a c t u a l - l y takes place a t t h e Tarawan coral-islands; where U r . Hale found a n a t i v e name f o r * b a s a l t i c stones i n t h e roots of t r e e s d r i f t e d t o those shores'."
Mayor f a i l e d t o f i n d theserrocks among the c o r a l blocks and supposed t h a t t h e members of t h e Exploring Expedition had mistaken blackened limestone f o r b a s a l t . The matter rested until 1939, when Schultz again found them, He only meations (1940, p, 48) c o l l e c t i n g lava but (conversation, 1953) observed many volcanic blocks, a dozen o r more up t o t h e s i z e of a man's head, s c a t t e r e d on the r e e f . His
specimens were brought baok t o t h e U. S. National Museum and were found t o be compact o l i v i n e b a s a l t . They a r e being studied f u r t h e r by Gilbert Corwin, who says the rocks a r e o l i v i n e b a s a l t s , such a s are t y p i c a l of P a c i f i c islands. Schultz supposed t h a t they might have been throvm up from t h e s i d e s of t h e i s l a n d with t h e niggerheads.
For an idea of t h e geology of t h e two b i t s of land on t h i s reef, we must r e l y almost e n t i r e l y on Mayor's account.
Sand I s l e t i s "a mere accumulation of fragments of Lithothamnium s h e l l s , and broken c o r a l
....
only about 5 f e e t above high t i d e l e v e l , "The loose and unstable nature of suoh debris l y i n g on a f l a t reef sur- f a c e makes e n t i r e l y probable t h e changes in s i z e and shape of the i s ? &
indicated i n t h e diffexent aocounts and maps, There i s no suggestion anywhere t h a t any of t h i s m a t e r i a l i s consolldated o r oemented t o t h e r e e f .
Rose I s l e t , on t h e other hand, seems t o be mainly a mass of suoh d e b r i s t h a t has been consolidated i n t o a "coquina" or reef-conglomerate suoh a s i s a common f e a t u r e of o t h e r a t o l l s . Probably t h e word "coquina"
i s improperly used here, a s t h e m a t e r i a l i s not primarily composed of s h e l l s . Mayor's description of t h i s follows (1924, p. 74):
"The tree-covered rooky center of t h e i s l e t i s composed of a ooquina consisting c h i e f l y of wave- worn fragments of lithothamnium and a l s o r a r e and
occasional fragments of broken c o r a l , such a s Favites, P o r i t e s Symphallia Pocillopora, and s t i l l more - .
Ihalf-valves of Tridacna and gasteropod s h e l l s , and r a r e l y Acropora.
---
~ m b e w a r many wave-worn e spines of Echini suoh a s Cidaris were found, a s was a l s o t h e muuh corroded ulna and p a r t of t h e s k u l l of a small cetacean about t h e s i z e of a blackfish, t h e l a t t e r being embedded in t h e coquina about 8 f e e t above high-tide level. A l a r g e amount of organio matter, dark brown in color and derived from t h edecomposed r o o t s of t h e Pisonia t r e e s , permeates t h i s coquina t o a depth of several f e e t . A l l of t h e
f o s s i l s found embedded in t h e coquina a r e forms now l i v i n g on t h e r e e f - f l a t , which have simply been tossed on shore by t h e waves."
The -hei'ght.of t h i s conglomerate above the reef surfaoe i s r a t h e r remarkable f o r such a small i s l e t . Mayor says, "On t h e southeast side of Rose I s l e t t h e sand-beach i s reduced t o from 1 t o 5 f e e t in width a t low t i d e , and c l i f f s of ooquina from 5 t o 8 f e e t high f r o n t t h e sea
....
A f e w f e e t inland t h i s rooky ledge r i s e s t o a height of about 11 f e e t above high-tide l e v e l , "
Schultz (1943, p.3) says t h a t on t h i s w u t h e a s t s i d e t h e
i s l a n d apparently i s being eroded away, Here, again, on t h e southeast shore, i s some beach-rock, s a i d by Mayor t o be more recent t h a n t h e I1rocky matrix of t h e i s l e t , " Schultz (1943, p.
3)
adds, Y?o t h e e a s t of t h e i s l a n d f o r a few hundred f e e t a r e loose s l a b s of coral-shell conglomerate rock l e f t on t h e r e e f , which may have a t one time formed p a r t of t h e island." These must be s l a b s of beach-rock a s shown by phot graphs.
On t h e northwest s i d e t h e i s l e t i s reported by Schultz t o be building up by accumulation of c o r a l d e b r i s ( i n c o r r e c t l y c a l l e d breccia, by Mayor). Here t h e b e a c h i s much wider, On t h e surface of t h e conglomerate where it. is covered by t h e Pisonia grove t h e r e seems t o be l i t t l e accumulation of loose material(Schu1tz simply says. t h a t t h e conglomerate i s lloverlaid:by coral-shell g r a v e l v v ) . No boulder ridges, d g e s , or lkampartsv' have been described.
. . . .
Soils: :
. .
The s u r f a c e of Sand I s l e t and t h e bare n o r t h p a r t of Rose I s l e t a r e apparently of unaltered o r s c a r c e l y a l t e r e d limestone d e b r i s , l a r g e l y of a l g a l o r i g i n , This d e b r i s i s s i m i l a r t o what i s found on bare:or ,newly formed p a r t s of most a t o l l s , except t h a t t h e proportion
o f ~ a l g a l m a t e r i a l i s unusually high here.
: , .
he
s o i l within t h e Pisonia. g&e i s very d i f f e r e n t and i s t h e subject of an extensive study by Lipman and Shelley (192L).
A goodd e s c r i p t i o n of t h e p r o f i l e d o e s . n o t : e x i s t , . b u t r r o m Mayor's casual remarks and Lipman and Shelley's d e s c r i p t i o n s of t h e m a t e r i a l s t h e y analyzed, a p r o f i l e can be roughly reconstructed a s follows:
. . . . .
TO^
l a y e r--
(Mayor)- 'lla r i c h ' chocolate-colored humus which i s of considerable depth near t h e southern end. of t h e grove,!I . .Intermediate l a y e r
--
(Lipman and ~ h e l l e y ) "a loose porous mass, v e r y l i g h t i n weight," (Mayor) "dark browni n c o l o r
. ...
t o a depth of s e v e r a l feet.". .
Bedrock
--
:(Lipman and Shelley) Iva compact, f ine-textured, almost pure calcium carbonate which shows no v i t a l s t r u c t u r e . It i s pure white, f a i r l y s o f t . . . 1 1 (but see Mayor's. description o f t h e coquina, which i s t h e same material, p. 11).
Lipman and Shelley regard t h e intermediate l a y e r a s being an i n t e r - mediate p r o d u c t i n t h e decomposition of t h e bedrock, t o form, with t h e additiori'of much humus, t h e s u r f a c e l a y e r of vlfine-textured,'mellow,~
o r g a n i o s o i l . " They had only a small b i t of s o i l adhering t o a pa,rtly decomposed r o c k , t h T s rock, .and
some
of t h e bedrock t o examine and wcrk with; ~ h e i $ - i n t e r p r e t a t i o n of t h e i r a n a l y t i c a l r e s u l t s i s completely dependent upon t h i s conception of t h e o r i g i n of t h e p r o f i l e , and i f more recent s t u d i e s i n other a t o l l s (Fosberg, i n press; Hatheway, 1953) a r e r e l i a b l e , t h e i r i n t e r p r e t a t i o n i s erroneous, t h e s i t u a t i o n s seeming moreo r l e s s comparable. Stone (1.951, p. 10) regards Lipman and Shelley's conclusions a s e n t i r e l y v i t i a t e d by t h e presence of b a s a l t fragments on t h e r e e f ,
Lipman and Shelley's analyses a r e a s follows (p, 208) :
---
: Rose : I n t e r - : Litho--
::water --
soluble c o n s t i t u e n t s--
:: I s l e t : mediate :tkamniun ::
-
: s o i l : product : rock :: Rose : : I n t e r -
. . . .
I s l e t : : mediate :. . . .
s o i l : : product :. .
. .
-- . . . . . .--. : p.p.m, : --
p*p.m,
" : p.ct. : p.ct, : p.ct. ::
:H20 a t 1 0 0 ~ ~ : 5.12 : 2.49 : 9,40 :: Total : :soluble : 'Loss on
: i g n i t i o n 22.114
I
31.09 j46.22 :: < . s a l t s : 26,oOCi
11,600'si
O2.l8 :
.20:
"16 "Ka2C03. .
1 , 8 3 7 : 2,171 : ~ 1 ~ 0:.
16-72 ~:
9.20: .46
::Na2SOq: 4 , :
2,435: ~ e ~ 0 ~ - 4 0
:
.481. ...
::NaCl. . :
1:
1,755: P205
:
20.94:
uc.60 "57..
i
C ~ O:
2 9 2 6:
35.78 :44,01 ".. . .
:
MgO: 1.75 : 3.34 : 7.46 ..
...
9 3 : 1,14 :
.87: .61 .. . .
'Na
: 3 :
1.39 ..35.. . .
iiC28
:
-23: 2 3
-15.. . . . . . .
'.. .
:TOTAL . . ~ 99.9'7 ' 99.66 100.40
The s t r i k i n g f a c t s about t h e s e analyses a r e t h e increasingly high per- centages of A l , P, S, Na, and K (from bedrock t o s o i l ) , compared with decreasing percentages of Ca and Mg and very l i t t l e change i n S i , a l s o t h e g r e a t e r moisture-holding c a p a c i t y of t h e organic s o i l and t h e Itinter- mediate product.
Lipman and Shelley's explanation of t h e high aluminum content and low s i l i c a content is ingenious. They explain, "The aluminum s i l i c a t e i n t h e o r i g i n a l rock undergoes decomposition through r e a c t i o n with ammonia, formed f r o m t h e decomposition of t h e s o i l organic matter o r of t h e b i r d droppings on t h e i s l e t , Such a r e a c t i o n would be followed by t h e leaching out of t h e ammonium s i l i c a t e formed and, while allowing
of t h e accumulation of alumina i n t h e s o i l , would prevent accumulation of s i l i c a there," This would n e c e s s i t a t e a reduction of 36 times
i n
t h e weight of s o i l decomposed t o y i e l d t h i s amount of alumina,The two authors i n t e r p r e t t h e increased of sodium, potassium and s u l f u r a s r e s u l t s of t h e g r e a t adsorptive capacity of t h e s o i l , d i f f e r - e n t i a l leaching, and increment from spray.
The astonishingly high phosphate content of t h e s o i l and t h e r a t h e r high content of t h e "intermediate productJ1' they regard a s r e s u l t i n g from
simple accumulation of the phosphate of t h e o r i g i n a l rock, without even taking i n t o account t h e b i r d droppings u s u a l l y considered t h e source of such phosphates. The correspondence of t h e f i g u r e s with those f o r
aluminum would suggest t h i s conclusion, b u t t h e n t h e problem would a r i s e of what had a c t u a l l y become of t h e phosphorus in t h e droppings of t h e l a r g e b i r d populatior t h a t i s found on t h e island.
The p i c t u r e , i n l i g h t of i n v e s t i g a t i o n s , incomplete a s y e t , i n t h e Marshalls, supported by a survey of t h e l i t e r a t u r e , appears t o be a c t + w q u i t e d i f f e r e n t . Generally, under P i s o n i a . f o r e s t , a l a y e r of pure humus, corresponding t g Mayor's d e s c r i p t i o n and
i n
reaction (pH b 5 t o6 ) ,
accumulates. :Usually these f o r e s t s a r e inhabited by l a r g e numbers of b i r d s , as' on Rose I s l e t . Their. droppings (normally pH 6 ) a r e a c i d i f i e d by the, humus a s they a r e washed down through t h e humus l a y e r , and t h e f i n e l y d i v i d e d c a l c i u m phosphate i s dissolved. &en
it
reaches t h e sand and rock beneath, i t becomes a l k a l i n e a& t h e r e f o r e insoluble, pre- c i p i t a t i n g out and cementing t h e loose calcareous m a t e r i a l together.The a c i d s o l u t i o n tends t o d i s s o l v e out t h e calcium carbonate and per- m i t s
it
t o be. replaced. by calcium phosphates. Thusa
cemented l a y e r o r h a r d p a n i s . formed immediately beneath t h e humus l a y e r , . . ,.: This'process i s not a t a l l similar t o t h e one suggested by Lipman and Shelley. : It, would not account f o r t h e enormous concentrati.on of aluminum,' n o r t h e r e l a t i v e l y low l o s s on i g n i t i d n . It i s c l e a r , from t h e two a u t h o r s , , d e s c r i p t i o n of t h e i r soil: sample "containing many un- decomposed p a r t i c l e s of t h e o r i g i n a l 1Lthothamnium rock," and t h e f a c t t h a t t h e i r sample was material adhering t o t h e surface of t h e p a r t i a l l y decomposed rock,that they did not have a t y p i c a l sample of t h e pure
humus a s described by Mayor. The i g n i t i o n l o s s would l i k e l y have been much higher i f t h e sample had been representative. .The high aluminum
content may well have been t h e r e s u l t . o f contamination by decomposed pumice pebbles, common enough on atoll's, o r even f r o m t h e b a s a l t . How t h e , s i l i c o n was. l o s t i f so, i s not..cl_ear, e x c e p t t h a t
it
t e n d s t o leachout under t r o p i c a l conditions.
. .
There .is a record of subsequent, samples being collected f o r Lipman by d h e r n o r Pollock, but though they
were
studiedfor
s o i l micro-organisms, n o more chemical analyses were reported. 'Further s t u d i e s t o a s c e r t a i n whether t h i s high A 1 content i s a general f e a t u r e o r o n l y ' a l o c a l i z e done. w o a d be d e s i r a b l e , . .
One .other f a c t revealed by Lipman's i n v e s t i g a t i o n s i s t h e &usually high concentration of water s o l u b l e s a l t s i n . t h e s o i l ( s e e t a b l e o f : analyses, p. 13). The authors mention, " I f our analyses a r e t o be con- sidered a s even approximately c o r r e c t , ' t h e Pisonia t r e e i s t o b e regarded a s one of t h e most s a l t - t o l e r a n t p l a n t s of which we have record a t
:
present." They point out t h a t t h e t o x i c e f f e c t s of t h e s a l t s &y be somewhat mitigated by t h e high content o f , organic matter present but consider t h a t t h e t o l e r a n c e i s s t i l l remarkable. This concentration may well be of s i g n i f i c a n c e i n connection with t h e extremely s m a l l land f l o r a of t h e a t o l l and possibly with t h e l a c k o f success of t h e coconuts planted t h e r e repeatedly,
In a b a c t e r i o l o g i c a l study of t h e s o i l samples collected by
~ o G e r n o r Pollock, Lipman and Taylor (1924) found t h a t t h e numbers of organisms were enormously higher i n t h e humus-rich s o i l i n t h e Pisonia
f o r e s t , much lower i n t h e s o i l where Boerhavia and Portulaca were growing, and extremely low where t h e r e was no vegetation. This i s exactly what would have been expected and does not r e q u i r e fuxbther comnient
.
The authors found, a l s o , t h a t both n i t r i t e and n i t r a t e producing b a c t e r i a a r e present i n a l l t h e s o i l s , and t h a t t h e i r n i t r i f y i n g a c t i v i t y i s more o r l e s s proportional t o t h e amount of organic matter i n t h e s o i l s . What was probably Azotobacter was found, but it was concluded t h a t such
organisms ,!'do not f i n d conditions propitious f o r t h e i r rapid development i n competition with other fornis which occur there,"
Land Flora
The land f l o r a of Rose A t o l l was f i r s t described by Pickering (1876, p. 236):
'!The whole f l o r a of t h e i s l a n d consisted of but two species of plants: one of then, a s w i l l be perceived, additional:
Portulaca (No. 1 )
.
Normal; m u l t i s a u l and p r o s t r a t e , having t 6 e habit of-
P,---
oleracea, but much l a r g e r flowers; p e t a l s f i v e , yellow, Growing i n a s c a t t e r e d manner on t o p of t h e beach, and i n a l l instances out- s i d e t h e grove.(Cal i d i a ovabifolia?); b i s (No. 1 Paumotu coral- i Constituting t h e grove; some of t h e t r e e s being f i f t y f e e t high, with t h e t r u n k four f e e t o r more i n diameter. Additional anomalies of growth were here observed: a s two proximate upright branches anastomosing ladder-like a t i n t e r v a l s ; and s e v e r a l instances of upward-tending branches, a s i n t h e t r e e s seen i n t h e d i s t a n c e on S e r l e and o t h e r coral-islands. The timber proved on examination t o be b r i t t l e and t o a l l appearance worthless."
Pickering's observation of t h e two p l a n t s had been reported e a r l i e r by Dana (1849, p. 309). The p l a n t s were discussed and i d e n t i f i e d a s Pisonia grandis R. Br., and Portulaca
-
l u t e a Sol. by S e t c h e l i (1924) who was studying Mayor's specimens, Mayor nave t h e second enumeration of t h e f l o r a , and found one more plant, ~o&ha;ia t e t r a d s Forst.,
growing on t h e rough limestone surface of t h e north p a r t of t h e i s l e t , with Portulaca.I n 1938, Bryan recorded no n a t i v e p l a n t s o t h e r t h a n those t h r e e ,
which i s a remarkable f a c t , It would be i n t e r e s t i n g t o know when Boerhavia took hold. It would probably not have been missed by Pickering, who was f a m i l i a r w i t h it and had found it on s e v e r a l of t h e Tuamotus. No account mentions p l a n t s other t h a n t h e grove 'of t r e e s , between t h e time of t h e U. S.
Exploring Expedition's v i s i t and Mayor's v i s i t .
I n t h e U. S. National Herbarium t h e r e a r e no specimens from Rose A t o l l collected by Pickering. He may not have made any c o l l e c t i o n s ,
There a r e s e v e r a l sheets of Pisonia grandis from l a t e r c o l l e c t i o n s , however:
Bryan 1382, Aug. 4, 1938; Wray Harris 2 Q , April 1938; Schultz 26 and
27, June 11, 1939. There
i s
a l s o a sheet of Portulaca l u t e a ,m.
-
I n t h e B. P. Bishop Museum (infornation kindly supplied by
E.
Brvan. Jr.. curator) thkre a r e sheets of t h e three- phanerogams:
E E ~ !
- v , -,
grandis: S e t c h e l l 40 (collected by A. G. Mayor, J i e
6,
1321~);W s
Harris 274 and
a,
April 21,1938; Bman
1382, Aug.4,
1938. Boerhavia tetrandra: S e t c h e l l5 1
(collected by A. G. Mayor, June 6, 1920-H a r r i i , April 21, 1938, and
a,
November 30,1937;
Bryan1384
Aug.4, 1938.
Portulaca-
lutea: S e t c h e l l52
(collected byA.
G. ~ a ' o r ) , June 6 , 1920); Wray Harris 301 A, Nov. 30, 1937; Bryan1383,
Aug.9,
1938.
-
The l a t e s t addition t o t h e f l o r a , due t o human interference, i s t h a t of t h e coconut palm. The s t o r y of t h e Rose A t o l l coconut palms i s q u i t e intriguing; t h e palms flourished a t t h e time of Rantzau's visits, but had disappeared by 1900. Of t h o s e planted by Rmtzau, one remained in 1920, s t e r i l e , probably as suggested by Dumstrey, because it was choked by t h e P i s o n i a t r e e s . The nuts planted by Terhune i n January 1920 were growing i n June, but had
a l l
disappeared by 1922, when Pollock planted s m e new ones. Bryan i n 1938 found about 20 palms, 8 l a r g e and a dozen small. Schultz (unpublished notes) observed seven l a r g e t r e e s and two small ones, besides s e v e r a l recent plantings now 1 to3
f e e t high. The t a l l palms were bearing nuts, and photos show t h a t some of t h e f a l l e n nuts may have been sprouting. By 1953 t h e t o t a l number was reduced t o 1 2 and t h e s e were bearing heavily, andit
is hoped t h a t no more were planted, and t h a t Rose Atoll w i l l have a chance t o increase i t s f l o r a by n a t u r a l means only. Why t h e palms have f a i l e d t o survive and multiply, when some d i d grow i n t o a d u l t t r e e s from planted nuts, i s hard t o explain. Perhaps t h e coconut palms were destroyed by a typhoon between1873
and 1900, whereas t h e Pisonia grove was seemingly unaffected; t h i s is possible s i n c e Pisonia t r e e s a r e p r a c t i c a l l y in- d e s t r u c t i b l e , new trunks springing up from f a l l e n ones (see below, Vegetation). Most of t h e plantings of nuts probably f a i l e d very early.Another possible explanation has been suggested on page
l.4;
it i spossible t h a t t h e high concentration of water-soluble salts i n t h e s o i l prevents coconut seedlings from developing. The r a i n f a l l of Rose Atoll,
i f estimated a t
77
t o 110 inches a year, i s not very heavy; andit
may be i r r e g u l a r .In
any case, t h e minute i s l e t may not be s u f f i c i e n t i n area t a permit t h e formation of a fresh-water lens, and t h e palms may s u f f e r from physiologic drought. There may be a l s o t o o g r e a t an amount of sea spray f o r coconut seedlings t o do well. In this connection,it
may be remrked t h a t t h e t h r e e n a t i v e p l a n t s a r e very hardy ones, often found alone o r with a few other such halophytic species, on t h e most d e s t i t u t e a t o l l s . Schultz (unpublished notes) a l s o records plantings of bananas, papayas, anda
few o t h e r plants, and indeed a very small banana plant is d i s c e r n i b l e on one of h i s photographs. B u tit
i s notknown whether t h e s e plants have persisted.
There i s only one record of a macroscopic land cryptogam, a lichen, which Bryan collected on t h e trunks of t h e Pisonia t r e e s , and which has not been i d e n t i f i e d a s yet (Brmn
