No. 75 Interrelationships of the Organisms on Raroia Aside From

No. 75

Interrelationships of the Organisms on Raroia Aside from Man

by blilaxwell S. Doty and J. P. E. Morrison

Issued by

THii PACIFIC SCIENCE 3O.ARn

National Academy of Scicficeri--National Reseamh Couricil

Washington, D. C.

November 30, 1954 INTEBIELATIONSliIPS OF' THE ORGUNISMS ON RAROIA ASIDE FROM MAN by !~4axvvel.lS . noty and 3 . P . E. Morrison

Sea Reef in general arid pools ...... 2 ... HOP80iZOBOW profile study ...... 5 Sea shore ...... 5

Spurs and. grooves 5 ...... Algal ridge ...... 6 Arnphiroa zone ...... 7 Hslioporazone 8 ...... Pool. zone ...... LO Excurrent area ...... 1.1 Intertidal and spray-viet shore ...... 12 Sea beach ...... 14 Guettarda forest ...... 18 Lagoonshore ...... 21 Lag0011 shore above high tide line ...... 21 Lagoon intertidal. shore ...... 22 Lagoon subtidzl shore ...... 22 A comparison of: the other six pofiles studied ...... 27 Sea shore ...... 27 Spurs and grooves ...... 27 Ugal ridge ...... 28 Reef flat ...... 31 Intertidal and wave-net shore ...... 33 Spray-wet shore and sea ramparts ...... 36

Sea. beach ...... 37 Guettarda forest ...... , . 40 Lagoon share below high tide line ...... 46 Reefpatches ...... l,g Vertical distribution ...... 53 Channels ...... 57 INTEBRFLATIONSHIPS OF THE ORGXUSMS ON RAROIA ASIDE FROM MAN by #am:ell S. Doty and J. P. E. Morrison

Having in previous sections of this report (Atoll Research Bulletins Nos. 18, 31-34) enumerated and given the geographic distributions of the individual kinds of organisms, and discussed the physical environment me can logically pro- ceed to a more synecological discussion. At least we can report our major ecological observations and the syn- and autecological hypotheses derived from these observations.

To facilitate the gathering of information for this phase of our study of Raroia a number of areas (transects) were chosen for more intensive study. All of the members of the field team narticipated in these studjes, and ?,heir aid is herein acknorledged. The locations of these transect areas on the atoll may be seen in Figure 1. In the transect areas r, search was made for tne living organisms present, These have been reported in Atoll. Research Bulle-tins lS, 33, 34. Across each transect area a profile was studied in reference to the distri- butioa of the physical and biological features of the transect. The profile positions in tne transect aTeas are shorn by the let-tered solid lines wi.t'nia each area. The letters correspond to the profiles on Pigure 2.

In this cliscussion reference is made to Figure 3. This is an idealized profile disgramming the typical elevational features met with in crossing the atoll ring. Essentially, it illustrates that nhich can be walked upon. This profile is a summary of Figure 2, the proportions are similar though no particular scale has been follo~red.

The description is organized as a discussion of the ecological units of the atoll under the folloviing headings:

I. Sea Reef in general and 2001s

11. HOPJOHOINO profile study A. --Sea shore 1. Spurs and grooves 2. Ugal ridge 3. hphiroa zone 4. Heliopora zone 5. Pool zox 6. . Excurrent, area 7. Intertidal and spray-met shore B. --Sea beach C. Guettarda forest i. Lagoon shore above high tide iirie. 2. Lagoon in-hertidal. shore 3. Lagoon subtidal shore

1x1. A Comparison of the other six profile,? stdied

A. Sea shore

1. Spurs and Grooves 2. Algal ridge . . 3. Reef flat 4. Intertidal and r.:a;re-net sLoyc 5. Spray-vet shore arid. sea rmnpart,s ,. .

V. Vertical disiribution

VI. Cnannels

I. SFA REFIT IN GHJEWiI, AED FOOLS . . The reef flats (Fig. 3) of Ecaroia are narrow (Fig. 2), usua.l.ly. I..ess tkn 100 meters wide, and in general the pool of mter on the red f2.a.t v;as deepest-L near the shore. This, %hen considered in rehtlon to the algal rldge, 5s in the position of the ba&:ridge trovgkl of the niuch vrider Karshail. Xsl.ar~dsreefs. The whole reef flat being only perhaps a hundred ineters wide leaves I.:.-ttle place as a ruie for the inr?er area of reef fl.at characteris%ic or^ reers kavirig a greater width between the margin and shore.

The wzter comes in over the reef margin (Ftig. 3) wl.tb each wr:-;e, except at lorn tide during calm weather. The niovenieilts on the reef Cat jvst as the tide began to rise (Fig. L,) were determined by catchifig the ~noveij!e?>tof dy spread on the surface. The wate-. comingin over an aLgal. ri.6g.3 passes in toward the shore and to the righ.t azd left (Figs. LR, C, D, E, F), and then o!it over the reef margin where it is low. This general pcttsrn ms consistert but at extrenies of tide, and pesumably at; times of other extre!nes such a? -:uind or , .. the course of large waves, the details varied. As' an exaqole, at :.s:-..gg mid tide when a lot of water vias csming in and out over tile reef edge, a 2.7s patch followed course "F" in Figure 4 rather than m 5 oriori se:ect,cd pa&h paldlel to "C".

The reef can be divided, by recognizing dxtreines, int:o 5.nctirrent an2 2- current areas on this basis of direction of water flow siter coxing in over

-2.- the reef margin. The excurrent areas sre devoid of algal ridges. The incurrent areas usually have an algal ridge b'~tthis may he a.bsen.t, the reef edge merely being higher here, or it maj be a low cuesta in form. '&e leeward reef flats are such al.ternat,in,: inc.urrent and excurrent, areas.

Excurrent areas rather consisLen-l;ly appear .opposite the channels between the islands, but as the more leeward reef is appronched, incurrent areas and excurrent areas alternate with one another even opposite island masses. Excur- rent areas are i~uck reduced as the more windv~wdparts of the atoll are approached and in the most vrindward reef areas may 5e absent, even opposite the channels, which are much more abundant (Fig. 1) here. In such cases the algal ridge is neariy continuous and the water n.orrr.aU.y passes across the atoll rim only in the direction of the lagoon. At least the water flow over the edges of the viindward reefs and into the lagoon without the regu1a.r tide3 reversal of direction characteristic of water flow in le=~ard ehanneis.

The reef flat was far more 'int&isively stl~diedon the leeward transect north of the village of Garumaoa (Fig. 5). 1,ocally speaking, the transect ran across the pieces oi' ].and known as Tomogagie arid Homoholno. The profile of this transect (Hoinohomo) appears as figure 2G. Here evidence was gained. tb.a.t seems to indicate the reef may be divided into areas tinct become uncovered with the lowest tides and areas which do not become uncove~ed. The areas that be coin^ uncovered become uncovered. rather quickly after the waxes cease breeking over the aigal ridge and once the tide rises so sufficiently that the waves again begin breaking over t!le algal ridge the whole tide flat is rather soon again covered with water from the Eeef ri&e line inshoreward.

At high tide water does in part go back out over the ridge in incurrent areas even ix regionshaving a rather high algal. ridge. By standing tit various distances out on the reef flat it was determined that the approximate point of division beheen where the water, at high tide, moves back toward shore after coming in over the algal ridge and where it motres back out over the algal. ridge is the approximate location of the reef ridge line; though this varies out into the Amphiroa doininated algal-coral zone under some circumstances. Dyes dumped into the water on the reef flat at various stages of tide level revealed rather consistent circulation patterns over the reef flat. The water regularly moved as described, & toward the pool. zone, laterally toward the excurrent areas, and -out over the excurrent areas. iVater, in early July, coming in over the reef edge jn the xorning was near, or a little below, 26 degrees Centigrade. Twenty meters inshore, in an incurrent area the vater would: be betxeen one half and one degree vca.rmer and this wwming of the viater continued into the outer edge of the pool zone where the maximum temyeratures:.mere observed. In this case, they could be expcted to be in the order of ai&gr.ee to a degree and a half wvmer than t,hose ob-Lained at the sea's edge.

.To~rardthe inshore edge of tine pool zone, the temperature dropped again. The lowest temperatures were measured in rilis of water ruanir~gout from the island conglomergte. In one case the temperature of a. small pool near high tide line, but connected to the channel of the pool zone, was 29 degresa Centigrade in its central. part, the inner edge, where the waterwas about 1 inch deep, was 27.8 degrees Centigrade, and with khe bur0 just cbvered in a. smdy incun'ent rill of mater running into the pool from under the island conglomerate the teclpera- ture was 2'2'7 degrees Centigrade. Note in this connection the path of dye patch "A1' in Figure 4.

As the chanxel along the inshore edge of the pool zone mas fol.lov:ed tol:ard the excurrent area, typically the tempera-ture of .the wcter r:as obssrved to h- crease in temperature about one degree. Then as the reef' f!at v~ascxmsed again, folloning tine excurrent &ea out .to the sea again, the temperature increased perhaps another degree, until at the most .the temperature vias aL0u.t 30 degrees Ce~.tigrac'e. It was lust in this area of' niaxiinuin teniperature that a certain soft coral was found. Beyond this point the re;mated i.-nmsh of cooier mater with each wave quickly 1ot:ered the teinperature .to that oi' tke sea beyond and outside the reef.

There are essentia.liy two kinds of pools associated d.th sea shores, both of them are calm ever-submerged habitats. The simplest is the ci.assica% ti.e.e pool. with its con~im~ousrim. Such pools [email protected] thought of as being smJ.&- tide pools in consideration of the fact tlxt vken eqj~sedby .the receding tides, waves or spray, their level reriains con~t,ant:~except as it may chnge through addition of rain mater or, by e-q~oration. The :secoqd iy~econsists essentially of areas nith a restrtctod drainage. The surfaces of this %ype, rhen exposed, slowly lower md may be 'thought of as a 1non-co~1st8.nt-leve~.type. Arovmd the former of these two types there is often a .sharp c:mnge in the hiota I j associated with the surface level. Such a change is absent at tne high water lsvel in. th8 latter ' type. . . . . ,, Tidepools are convenient piaces in !.ihi.ch to make observa.tions. They at- tract biologi.sts for they are often centers of considerable hiolo~icnlactivity. Recently, for iAe reason that this biological actLvity is of: geological import- ance, the interest of the ge013gists (e. g. Emery,:Bull. Geol. Soc., 1.9:,6) has been attracted. All of -the tidepools can persaps: be :di.fferentia.ted .to a certain extent by their position in respec.t to tide Level, &s supralittoral, littoral, and sublittoral tidepools.

The constant-level pools of the island conglomerate ase supralittoral pools often of low salinity or of high salinity. These have been discussed at length under the blue-green algae in Part 2 of Ato1l'~esenrchBulleti* 1\10. 33.

. .. LittoraL pools are nearly .'a&ent except for thereef flat &I the channels both of which are non-constant-level type pools. They are discussed below in . . greater detail. ... .

Sublittoral pools of the cbnstant-level -t;-pe are nearly absent, unless one vrants to consider the vhoie ocean as one pool. The concentration of biological 'materials .around the shores of the sea favors this classification. Certain surp;e channels, the incompletec~annelsbetween the isimds and especially the lagoon;. , itself, are essentially s~blittoraltidopools of the non-cons-tan.t-1-evcl type. Hoviever, , ondownmincl lagoon shores mhe~ethere (is a rkef, the gross aspect, like the littoral shore of the ocean, is thatof a con$tant-level. . tidepool.

... . . IS. HO?~OHOIVIO ?ROJILE STUDY (Figros 2G, 4 an2 5)

1. Spurs and Grooves. The so-cail.ed "s~wgecharinels" and "r:'.dges" re- ceivved cor.siderable, but entirely superficial., attention. Classica1l.y it !.s here that the atoll rim is growing upward and. ac~vancingthe surface of the atoll outward. Neweli has seen the seme fea-Lures in limestones vhich were of an 00-. iitic sort formed. inorganlcallg. In E:aw;iii, on the basll.tic mterial~under water ~rherethese are partially co-versd vith smd, the sand aild bbasdtic material show to an observer in a plane or boat as rediaS;.y arranged el.ongated arem. Thus must be elimizatzd the explmation thzxi; the spurs and grooves have fomed entirely as ridges growing between tie now nresent channels. Ul of this points to an erosionel origin of these spurs and grooves as Cloud (Bull. Assoc. Petroleum Geologists, 1952) tas claimed.

At Raroia the spur md groov.: area. appewed (Fig. 5) to be a mass of 00- -litkon-. - onlcodes with o~13.ytraces of other coralline algal ripecies. Coral mi- rnals were few. In .the heads of moet cf the grooves there ware to be found colonies of a Millepora, cihich extend do~m8.bout one feat. and out from approxi- matel.y the outer edge of the algal. ridge and tile ievll. of the reef fl.at inside the algal ridge. These !!'Iila:a col.onies form their om small. pools by their retLculate pattern of up~o;v1:.h. (Sse Figure 2 in Trs.ce:i, et al, Bul.1. Geol. Soc. Anier. for l948.) Cmtroceras clavdattirri coat,ed rceny. of the higliest parts of the spurs beyond the aa?ga?. ridge. Rarely were other than coralline algae present; hoaever, among tkese rarities mas a &uls~(a variety of pickerir&i or an undescribea species) and 1~icrod~i.ctyon01cm~re.i Setch., and s~ot~sof hlue- green dgae. 111 avery few places rather xell under even the lowest tide levels there was an increased abundance of Poc~10po~acn the tops cf the spurs.

The grooves beyond the algzl ridge at Iiomohomo dip sharply (Fig. 3) or :nay even be scmewhat, overhanging at their heads, Often .the hews 6f these grooves a.re broadened and fill.ed ~ith.~?hatmight be referred to as huge algalated lunps. mile no effort was made to determine more than the nat,ure of the superficial material of thsse it appeared that they ir.igh.t be fragmezts of reef rim br~ken off a?d lodged in the he&& of the grooves and tkn cemented Ln by the growth of such algae as Poro1.i-thon onkodes and Littionh:rllum species. From the rmnded shapes of the groove bottoms axa their containing roundec! boulc'ers and pebbles as well as their generally very snooth regular contours it vms assumed that in the grooves there was a lot of abrasion. This was inshuated further by the frequency of spherical clump of algal rna.terials (Microdiciyon o?.camuraj.) found there. Around. these irregu1ar:Ly arrmigec! huge algaiated Limps in t'ne ch'amel beds t.he broadening seen appeare6 to be what one might expect from *he abrasive action of particles being ~vashedaround their sides. In sone cises the hea.ds of grooves were nesrly confluent as though by extensi.ve cvergrcwth of the lodged reef fragments by corallice algae. A pros-trate Gelid-ium a?d fin extremely fi'le partially corticated Cermius, recalling Ceramium avz~lor~ie~awon but ~rith longer nodes awl more slender tkiroiighout, grow in small colicavj.ties of the w- --litkon --onbodes along cith Herposinhzia tez1e1.a (C. BE.) '(4aegel.i (Male thal.li were found displaying the assymetricd. iiatilre described by Eoeegesen) . It should be emphasized again that there was little nacroscopic.ally visible on the tralis of the grooves. The actual surface was usually covdred xith a characterless pink layer of coraUine algae, which insofar as we could tell, was always morphologically undeveloped.

Here at Homohomo the opinion was developed. %hit,perhaps jbpie&n_pk.06~~ is different from o.ther crustose sgecies of coralline Ggae in being ab1.e to develop rapidly, stand the brilliant illumination (other crustose corallines were usually res-tricted to cavities or shaded. areas) and a certain -mount of emergence with its attendent elevxbed temperatures and the osmotic changes in- herent ~ithdesiccation. Fur'chermore, since this species was ~pparent3.yex- tremely important in the life of -the reef it was interesting to entertain for a time the idea that such a species suddenly arising and spresding very rapidly would aid in explaining some of the uniform chcracterj.st,ics of coral atoi:ls.

2. Algal Ridge. The algal ridge at Honohomo was discontinuous (Fi(;. 4), being highest in what are being called incurrent areas md absent in what are being called excurrent areas. The surface of the reef, hovrever, was a unj.fornl pink coating of --Porolithon --onkodes. throughout. Seaward the algal ridge descended from its maximal heights of eight or tm.inches by a gradual slope (Figs. 2G and 3) onto the spurs and into the heads of the grooves. Insho,re~rardsimi- larly it descended to the reef fla* by a gentle slope, often a bit steeper than on the seaward side.

But few animals were to be found on thealgal ridge. On the sea side, the most conspicuous of these was setosa, which as n substii;uto for a good breakfast was certcinlv reason for ti& relative' scarcitv of this snecies near the village. In numbers the animals on the surface here were principally a limpet (Acmaea Siphonaria, or Helcioniscus sp. 11067*), a small barnacle (B~Janussp., l&and various morn or gastropod- tubes tihich nrotrude through- the algal.- cover vihich tends to overgrow all these animals. : Microdictyon okamurai is tine roost conspicuous non-coralline alga and appears on both faces of the algal ridge. Particularly on the inner face of the algal ridge, but,on the outer, too,.small spots of a blue-green alga appeared. , ...... The inshore side of the highestpart of the algal ric?ge at Homohomo mas deeply pitted with many of the pits being occupied bypencil urchins (12088).

These holes xhich the urchins were in were hoies such. . as are Wyplcally bored by sea urchins". . .

The smooth Porolithon onkodes cover of the al&l ridge extends i~orizontall~ inshore from the base of the algal ridge from a few inches to a Sex feet end.ng in a rather definite border. This bard-er, which usually could be located within a fewcentimeters, was called the reef ridire line (Fig. 3). It was on.e of the most consistent marks.on the seareef. Even opposite relatively large excurrent areas where no ridge was to tje f&na this resf ridge line could be j.dentified. In Figure 3; the algal ridge is shov.? in its full expression. Beneath the ridge four dotted lines are labeled a, 'k,' .Eand 4. These indicate the contour of the algal ridge in relationship to a groove bottom as one progresses from a strongly incurrent area to a less decidedly incurrent area, a, where tke algal ridge is an almost level topped cuesta. Further along toward an excurrent development, such as the large excurrent area at the sea end of the ierficial reef ridge material in time itself may disappeirr through weakening by s11ch so!.uti.on or Lorlnr: and 51& a7my during stsrns. I'he cavernous areas vrere the habitats for a host ofdifferent spec1.e~of fish and of crabs &id other invertebrates rare1.y seen out on the reef in the daytime.

3. Amphiroa Zone. The reef ridge line is the ?osition distingiisted by a trami-tion from Vfie sxocth Poroiitk~nnonkode:i surface do5te3 here and there by patches of a blue-green al.ga io a surface doniinrcted by ail hphiroa. Tkis -Arn- (1O90) is similar to A~nphiroaannu!.?t.a Le!:~oilie, hut is some;?hat larger. Fx,om observatlon this zone (Figs. 3 aim3 /+) :.la:: ttree mejor charcctcr- istics: 1) form and ?osiij.on; 2) structure; md 3) its pe~1.1iia' niota.

In form the hphiroa zone is a flat Ylat is q:rrite like a turf anri consists principally of but thisonespecies. St .forir,ed a zone abou.t five to fifteen meters wide.

It was observed that at 1.0~:tidethe Am~kiroacommity was out of %he nater. The remainder of tke reef flat or reef ~oolarea co~stai;tSysubm6rgt.d. At !ligh tide the water coming in aver he reof edge "dividedt' hers. The wa-ter inside the inner edge of the ----ktmmnhiroa zone pissing on in over the reaf ?Sat and that over the &hi.roci-.-- a?d ~utsidethe reef ridge I.ine scrgtng' back outvard. Esseritially the fee;ing was gained that, this was the ilighest growing for:~insofar as tide level is concerned on i're reef fI.at away from the high ti&e line at the shore itself. It was v:idest insho:-e of incurrent areas and most na?:aw, absent (or newly soj across excurrent areas:

There mas in a fe;: places some dsvelopxei-it of this a~sociafiontc tkCe seaward of the aigai ridge on tile izrges-i; aid f:i.attest topped spdrs. For. a series of :;uch flat to;?pe? spurs see Figure 5 opposl.te tn.3 third isiand flax t,he ri.ght, Kumekume, md just outside the line of byealrers.

In structure the -.,h&iroa - zone is a 2ur.f abog-i three centimeters deep over a roofif aid pi1;ar stZ.uchxe (iliagrii::imed in Fig. 3) akout thn or fifteen cen1;imders thick. The cavities are tee :iabi.ta+#s for a my-riad of invertebrate species and small fish. The important inhaoltant :'.nsofay as tlie solid S~JC- ture of tne reef is concerned appeared to be a. b1.auk "'bor%ng urchintt, &hk mstrc. (11095). This urchin can be gostul.ated as being responsible for boring the holes in xhich it ;s found and ths causing the renovi;l of c1.gc.l matcrid. Whether it consumes this material. or no-t is unkno-wn but sl,ouid be ;.ooked into. The tops of the chaml'ers or rooms pf Lkis portion of +,he red are open to the surface. However, this openirig is .increa:;i.ngly c:Luseri by P3roLithon pnlcodes which tends td convert the reef fl~there in-Lo B smowbh i~aveinei~tlike tiia.t of the algal ?idge area. The .-- Axphiron grows on top of this perforate?. a?.gal. pave-. ment ...... : . .. This zone is per&ps distinct vertical.ly but is not sodistinct horizontally. The biota here beyond the hn?hjjroaa itself i.s no-t. seemingly restric-ted to this zone, except for C&leroe urvillema mh3.ch qspeared ::ifk soma f~eql.3ency opposite incurrent areas as peen patches in the otheivise 'pink Amp'niroa turf. Corals such as those more abundilnt -in tine next zone inshorecar2 were present here mith 1.ower frequencies. Especially oppostte incurrent areas Ae1j.opora appeared most frequently. 'Phe h?o.Lithon benetit:? the Anr&iroe. and. eqecislly the animals in general in the cavities below the active grcc:i.ng level of the ?oro-- lithon are essentially those of the next inshoreward and lorer zone. ---Turbo arbrostoma was ratiler sharply limited inside thc reef r.idge line and tie major distrj.bution of this species on the Eoio:noh-imo transec'c ws in holes near the surface of t'ne An1ph5roa zme. It did, honever, occur in w~chlcmer. numbers in the next zone shoreward. In the Ampbiroa zme the boring urchins (Echinometra) were predominantly black urchins and in the more inshore zones a sT?i?lar.- FnK urchin beca;ne predominant. A most interes-tLng assoclatlon be.heen the shrj.mp, Craiigon frontalis, and the alga Z,m~byasgr.cl.idg, discussed idth the other blue-green algae, (Atoll Research Bul!..etLn !4o. 33), .:$as most ttlmndmi in the cavities under the ---Amphiroa though occurring Lwth out in .the :grooves and more inshore in t'ne next tidjacent zone.

4. Hsl-iopora Zone? At Raroia there was ca1y:vha"cigh-t be said to be an analogne of the Iieliopora zone (Fig. 3) reported hy Lad<, et nL., (Sour. of Geol. 58, 1950) at Eikini. At Earoia, Iielioporn (1.07 was novjhere conspicuous and prns found mith any frecp&cg at all oniy on tb.e sea reef 2t Fi~~aohomo ~mdthere pith regularity only insite the most incurroil-t area.;. Perhaps, it would be better to term -chis a coral animal cow, ~ithowtbei.ng too spec3ic as to vih.e%heror not a hyphen sb,ould he placed between coral ,aid snimal.

This coral cinl~nalzone or Heliopra zone /,Eig. I 3) was essentk1l.y a bcnd inshore of the ilmphiroa zone achieving i:cs ii;aximl breadth opposi+,e -';he incur-- rent areas and being absnt opposike axcux-ren.5 zres.8. !)n 'che :!onohoi:io transec:t this zone v:as about 20 met.ers broad. at its broades-t.

In general ths lowst levels in this region :Arer+ fif'tcen or txenty c%iti.-- meters below t'ne level of the highest levels. I'5e ilhole zone coiuld be thousht of as a series of holes with more or less incomplete rims. kt the semerd margin the holes were snialler and more 3earl.y closed cvei- as the 2~~nhiroazone mas approached.. Inl.ancl,, the holes were larger and -the rim potion Less conspicuous. Rim portions that reoched the lew& of the Bmphiroa. z-xe were populated above mith species of the Ar~phiroazone. Essentidly, perhnpe, th.is coral animal zom extended right under .the Amphiroa zone at l.e?.st t,o tie rsef ridge line {Fig. 3).

The depressions or holes in -this area ::ere connecteu sd as to drain toward the shore. Toc:arE the seai:ard edge of the zone these drzinage ckiains mere inconspicuous. Inshore the holes were deeper, larger and inore conspicuously continuous and almost no sol.id material reach52 the elevation of the Ainphiroa zone. The impression ga-tlered was that the rim materiel of the holes was i?ore in the nature of the regains of coral orgainis!ns that had grown 8116 died there, ra.ther than being of the nature of material such as island. conglomerate that has been removed by one process or mother.

" Ehis is the 'Wontipora belt" of Nenell, Atoll Research Bull. 36. E~J -8- Fie organisms identifying this zone by their distribution are -.-Diadema (11093); Poc3Uopra jll069) and Acronora. Abundant, but less corispicu- our are the same bhck --~%,n,~m,era (110s5~such gastropods as Crupa rieinus (11069) and mraea moneta mi-&pairs in small holes). Essentially this zone is not exposed to emergence at low pool water level. The organisms in it extJexid upwards to tile loviest vizter. Levels. Those which are mobile move so as to renia5.n submerged. As an example 7 ----Diadema became rather active as soon as the spines became emergent. The spines were act'ively .,. .,. tilted this vrzy and that until they came under the water surface or near1.y under it. In corres7ondence with this observation is the observation +,hat the size ,of the specimen is as a rule no larger than the depth of mater at the lo?!- est level in the particular pool area in vhich orgenism is stationed. That is to say the heignt. of the animal wae equal. to the depth of water at low pool level. Seaward the specimens aye smaller in correspmder~ceto t'ne smaller holes, which we presume to be due to the greatw rate of algal re;7!.aceaent of the material removed by the boring of the urchins and other forces.

A rabher interestj.ng series of observations on the ~eletionof .:;he non- mobile animals, e. g. Po'o+2&:,rz, !Ieli.opora and Acro;?ora,---- was ~cade. These or- ganj.sms apparently grori upward during periods of iiigher io'w tides and the corres- ponding higher low pool levels. On July 7 and 8 '&ere vas at Raroia, in corres- pon:!ence with favorable meatner, a series of exceptionally- 1.o~pool levels (and ti.des). At this time, it was noted. that -the -Tocillopora-. - - .- (11101.) vere more damaged by the ex.posure of their u;?pernio.;S ?arts than wwe close by bcropora---- colonies (11101). The effect is one of !cilli.ng the more ewosed parts of -these colonies. In corresporidence v~itkthe di.?ec.tion OP the prevailing r;ind =d the sun the more northern edge appeared to be killed Gn a greater extent Lnan the southern edge. l'h-cls, one could find rikat aq:~earedto be the dead base of the coral aniinal colony extending avray along the reef .lo the north anr! a-t the southern end a crescentic li'ring edge. This is iliu~'Gratedin our spechens and phot,ographs of -.Pocilbpora (1216s) and Ac-.oaara and another as yet unidentir'ied coral animal (12l693.

Not only are the animals killed at ti.me:. when the pool water level is low but indvcement. of Cke t,qrf-like nature of the aigni cover over the highest portions of this zone is encouragei! b;r the killing of algal tips. Ciiulerpa urvil- .--liana, as we1.l as toe hphi.roa of -:he next sea:~e.rd md elevatiocally higher zone appeared the next day alter me such exposure viit'r, all 'Kie long.% tips yellovr or white and presumab'ly dead.

It was in this coral animal or black urchil: -,on2 that -the only lriving 'un_ g& %as seen on the sea reef. In this zme the black k,orin# urchin, Ech.tnometra, gives nay in prtxiominarice So a very similar pink one (11905, 11130). This led to some disc>.~ssior,as to the c'istriil-uiSq of these sinall borin.n, uurchins. To gather more information the transect method vias resorS.!,ed to anrl the op:llations of these small. urchins in meter squares were covnted. The resu1.t~mere, in brief, at the imernost mete;. squa62 black bring urchins anci 13 pink ones (11131). kt station #72, in this coral.. anixal ncne, there mere !+8 bhck ones to 9 pink urchiw (11130). lit -chis poin-t tile counting wa.s disc~n.t.:..nuedfor counting further out into t:he -Amphiroa. --. -. zorie reveaLed t,he fact That the pinker boring urchin there had shorter thicker spines than the si.mi.lar pink one discussed fro~3nn,arer shore. PkeLner this was a third species r.f Echinometra, or a color form or an ecologj.cal form could not ke decided and the most our results gave us was the infonnatLon tha'c t'iiere is ally a gradual change in nmibsis across cora.1 animal zone and added support tc the idea that the area. under the Amphiroa zone is c1osel.y related to the nrestnt area. . .

5. Pool Zone. Be.Lween ,the cor.?.l anircai zone and t.he lou: pool. level at the seaward edge of the land is the teeyest, part of tine reef flat. In this region, there are fex objects that protrcde at lor pool level. Cssent.Lall.y, this pool zone (~ig.3) is a shal.10~channel fifty to sixty meters ride graJuw.1.y deepen- ing j.nshoreward to ritliin a few meters of the shore and then furthcr deepiiSng gradually as it passes alonq the reef from behind tthe iaccrrent areas toward excurrent area. The water fiows downiiili (Mg. 4) tonard the exc:~r.rent areas. At low tide, the wszer is warrcest in cen6ral regions of the pool zone (by about a degree on the Hoaohomo transect). it is coider &tt,he insho-e edge ii; cor- respondence witib the cold w'at,er percol.at,ing out of %he shore at lo~vGee aud agair? colder 2.t the sea ec?ge, 'OLI~not usually a.s so13 t;.er= .zs at the inshore edge. At high tide the w~tertemoera:-iures over the see? f:at are ra-<,her lunl- form. The bottom is covered v:i-kh a general;>* pi& sady layer. This, t.1.s at Bi~ini,was pedominiilltljr coralliw algal. materi.al, most1.y juvenile crusts, and sand. Tile sand itself consis-teti of foranini.fel.a and cizstic iragments ?re- sumably of the orgar:isms Living further out on -he reef fl.a.i.

There was littie in 'the my of algae sufficiently mctilre *ha+, could be identified, the exception of som felc clumps of Cau:!.er;3a pi~mL&,lt, (1103L) despite the fact tha.t the pinkcolor of the region seemed to resuit "om a pre- dominmce of coraliine slcae. As sand increas96, an3 t%e arens Secarne Less pink, it pninte6. out by Morrison that tilere mas a corres.poridi.ng iocrease in ei.cro- species. And in such san6ier parts Stroinbus SF. becane ner.haps the most ahund-. ant of the larger gastropods. In Less sax* parts where tihe coral.li:!.es T;.er* more developed, perhtips the best molluscan irdica.tor of this region rias to be found in &a grossularia. This spec5.e~of Drux- was qvi-ke distiiict by its low form and yeliow lip. Wth it,, especially as tk.ese ho species occurred Eearer the excurrent areas or down tne channel, GonioXthon SF. 6 ap2eered as an epizootic coralline alga on to? of this 2~.Si~iieriy this sine Gor!j.olit%inn- .- apueared in the centers of the small (3O Cm or soj microstolls resultin; r'ro~n death of -the center of coelentera.te coral heads., '

It is of interest to list some of the other irniam1.s of this rezion. They all appeared to obtain their food from the algal species directly or :idirect%y. Helioaora--- (13.107) was present in small xusbers. Df---. aderca (Il393, 2.1092) was present, in larger sizes and loi3ier numbers. The largest ap;jeai.ed i.n the deepest parts of the pool very near the shore, Lliere being fewer, however, in the middle of the pool zone. Perhaps, this rjas related to -tifie distribution of water temperatures. Pociliopora an6 Acropora appeared here bu'i; in lover numbers. Near the seaward border, but veqy indefhitely so, there occurreci a braj.n coral the colonies of which were so scattered that its distributjon wax very difficult to determine. Tllais, a species of the armisera-group, was found here. Cvpraea moneta, perhaps a better i~dicatorof 'the next zor:e out was rdso a.bunc1- and here. Cypraea helvola and 2. ca.pa-oer~entis_were here. 3li:a ir~orxte, a wee speckled "Cypraea" was suspected of living here, but .its s:lells mere usually always found empty and cast up with the coarser saindor 'in v~ithli'ttle gravels in holes in the isl.and congl.ornerate. Cwraea schilderoz.um in various forms or sizes was perhaps most typj.ca1. of this pool region. Various cone shells such as Conus mil-ec, 2. debrzeus adC. alLa.rr. and a. couple of others mere most easily found here too, but were probably in more seaward regions equally but there harder to Find at least in t!le 3aytime atlovi ticie. Toward the inner edge of the pool zone a tawny ---- PO$^-tes thrived even in the rock basins in the island conglomerate where sand gredhninated, but always at ieast just be2.o~ the lowest pool level. This species, mas so consistently piaced that it was used along with a black Hol.'thul.iar~ as an indicstor on the shore of low pool level. Several other animals were conspicuous Just belov: this louest pool level too; such as two gastropods,' a &m sp. and .the very i~terest~ingsmall red marked Conus sponsnlis. A pipe fkh, which seemed to be an undescribed species of CorythorJchthys was typically found here, especially in the 1-mger of the pools at the edge of the island cou@omerate.

As this inner edge of the pool zone is reached the color of the bottom becomes more b'om~ and is more sandy in nature but is s-till definitely pinkish in contrast 20 the brom of the intert,id::l regions above.

6. Excurrent Area. Logi~al1.y a discussion of this regi.oc (Fig. L) follov~s the discussion of incurrent areas which have predom3natki this s?ecific discussion of the sea end of the Nomol?oino traneect so far. The largest excurrent area studied can be approached, for the sake of c?escription, most, 1ogicall.y by con- tinuing our discussion as though assi in^ along the ?ool zone, following the course of the water which f?.ows through the pool zone and out thriugh tt.is ex--- current, region. As one novcs from the 2001 zone opposite an iucurrent area to- vjard the lip over vhich the water pours out of an excurrent zone the bottom becomes increasingiy smooth and tov:ard the lip becomes i.oni$.tudinally furrowed as though by gravel scouring. . . We speak of little else other than bothom for the shores of exc~rrentareas are the incurrent zreas to each side and the intertidal is!.and shore ama to be described below. This bottom is a pink pavement of what seems largely to be undeveloped Porolithm. It is, especially seaxard, a bright pink; though inshore it is more buff to bromish. The low pool level ~f the excurrent wea is marked with the same species of Porites and. the deeper areas with Diadem.

It is the relatively inshore portions of t,he excurrent areas that afe found the greatest deve!.opnent of H91ioporc in for,uat,ions termed by other a.toll workers, microatolls. The centers of these microatolls were covered as a rule by coraliine algae wkiiicii are of the genus Goniolithon. Uni'ortunatsly the thalli are so oddly developed, or underdeveloped, tha-t these ifflobby crvsts could hardly be identified to species as specific determi.nation derna~dsnot only fertile material but "nocmallg developed" thalli.

Thus far, we have been discussing vhat might be calleci the ':pool. zone" of the excurrent area and it has in it all the organisms charac%eristic of the pool zone elsewhere but they aye for the most part iliucil less a.bundant. The little association of Gonioliths and Jruix g~>ssularia_, hovisver, i.- more conspicuous here. At what me considered the "pool edge1' the bottom (Fig. 3 at, "e") was quite flat and just beyond begmi dipping more sharply toward the sea. On this lip mas' a'sea-facing, arc of yellov~soft coral. colonies ( Zoanthids )- in a single series, spaced about eight or ten meters apart. !hd here the mter ?.eve1 as least,,. even zero at lowest pool. levels, and the water tempexatures, were highest. Beyond this level, there v:&s rather constant mixing with. insurging. waves and the t6hpere.tures were measurably lower. , .. . , At'the pool edge, the increase in slope toward the sea Tias accompanied by the longitudinal grooving described above. These grooves were various in sizs and while coursing in a general ,cay parallel to one another they verc to ii srnail degree tortuovs and anestomosing. 6s a rule, they mere neither more than a foot broad nor a foot deep. Their bottoms werl broadly r.omded like pot hole bottoms. In the bo4;toms of these grooves, there va.s little cther than tke pink of coralline material. The ridge tops often ha6 the sane iL"iphi.ri>a as described for the incurrent areas or a few of the ot!?er sy:ecies of incurrent areas a~ranged in the same general serial order inwards froni the sea.

Aside from the organisms menilonec! tliread=, ~rol~-~~l~w~$ns..>.$& appeared in such excurrent areas on the ridges between these grooves. It was very characteristic of such places and might be scid -to have been the best iadicator organism. Rhile not strikingly developed s% the sea end of the Homohomo transect it was much more dcvnloped at the sea end of the large excurren'z area associated with the ckannele at Kukixa Rahi, at tne south end of the same j.slend and the islands called Kukina and &ire. Here it tended .to close over the tops of some longitudinal grooves enLj.re1.y. At i,Romohomc the tha:?li of tin~..sspecies mere rarely more than mere undeveloped buttons perhspr; four centi.meters in cliariietar at best and two or three centLneters in height. Those in s~.mila.rpo-- sitions a.t other stations developed from bases of similar diumeter .but specj.- mens returned to Honolulu mere up to twenty centimeters tali and trenty-five to thirty centimeters in diameter at 'the flat 'top.

At Vne seaward end of the reef pool. lip just discussed, the bottom pitched deeply and abruptly into the groove heads with. little in the my of the overhanging development found so often in incurrent area groov:? beass. . . No study of one or the channels between the islands (Fig 5) vialis niade in connection vrith the Rornohomo transect,. Channel information is col.lected in section VI.

7. Inter3dal adSpray-Vjet Shore. The intertidal region (Fig. 3) proper is approximately 22 centimeters high.." %e solid ccng?.omerated mterial is bromish in color, coatrasting with the pinkish sazdy, otherwise similar shore slope of the pool.. zone. Thilis region varl.ed in hldth as the slope of the beach - . changed all along the shore of the island and trmsec-t at Homohomo. Otherwise, . , it was relatively uniform in character. T'nus, it and regions inshixe of it were at times consicered separately as an ?'onshore area'! in contrar;t 'l;o the "incurrent'$ and. "excurrent" areas. The surface:; here nere in general. rounded and convex in contrast to what they nere in otfler places. This approximately 22 centizeter band mils usually a gently sloping shore rather continuous in slope with the pool floor. It was -terminated inshore by

"-" -&cording to Nemellts measiirements 35 centimeters. E~J a. steeply pitched. step or bench of j.sland cvngiomerate (Joosely speaking "beach roclcI1). In sane laces tinere mere out3.ier.s of islmd. cangiomemt,e or poo1.s cut to pool zone levels in the scawzrd edge of .:his isiand. con:$o!nerate bench. The outliers were in some cases appamn.llg,of the islpld cmgl o?iez.ate, but in other cascs they were very obviously, from the uniform orienta+Lon of the fos:;ils in them, fragments of reef. The outliers were found invarlous s.?.agesof under- cutting with this 22 cen-ti.met,er zone recognizable physiographicaliy and bio- 10tz;ically. In general as one ifloved up them vertically their surfs~ces'were si:u!- ilar in biota to the shore.

Contjnuj.ng inland anti u~.~wnr.dsa.bove tho intertidal zone above ?!hat, r:a:. be mean high tide Line t'le roc!< rises almcst vertically forabcut two feet. The surface then levels off at ahou? 100 cent$@eie-rsz'mxre the low pool ;.eve].. Rhen rather dry, a.; tines of low tide, this area is .biackish an8 appears from the air (Fig. 5) as a black Xne around the island.. it provides a good poi.nt of departure i.n inter?12etinq aerial photographs (Pig. 5;; as the seaw&i-d edge may be taken as high %ide line.

Tie organisms insofar as algae are coacerned ne-t rnlcrnscopic forms mostly unstudied yet.. Those stutiied and. ?.den-tified hve turned cut to be blue-green algae, v;ith soine exceptions, and for the most par.: forms of &t*hp~i&s. Cn3- ---tacea (see discuss;:& under Xymphy-ba in A.tol.1 r?esea?ch kill.e-bin No. '13). 'This organism mas spread all over the generhl area under di.scussion and was respon-- siXe for the black coloration of the rocks.

Between the lorn pool and leveland zbout +,hree four&$ of the way to hig3 tide line Yne conimon yas-bzopod ~~~I granul-ata with mother g8,stropod, hipvocastaneum, oczupied the remeirider oi the intertit-al region up to tbe mean level of higb wate.r.

Migrating so as to remain just ahove the :xatcrls low surface befxeer~vmves end especially conspicuous at night was je~-ta_&is~2~.Xlis species codd be expected as the predominant living orgoniern cf macroscopic size upwards for perhaps forty centimeters above the vmte~where i.t overlqqed the loser levels of the range of a Tectarius. Jus-t ke1.0~the levels. of the KeYita a carnj.vorous gsstropod, Cronis. cariok, Zed on tk'e fi&x~&~. The ecological implj.cations here, especially in reference to m5.gration of the Nerita, are most interesting.

Tectarius did not seem.to be a species vhich rni.grccbed :i-t'r~ the ti&es and. its intertidal range was rather high. In fect, it ?,as wkmt might be called a spray zone, or low spr8.y zone; habitant. It rarigeci a.t the sea end of the Homo- homo transect. about t'nj.r.ty-six centimeters above tile ordinwy nave splash iina' nith the general lover level of its distribution being about thircj -to forty centimeters lower.

' Perhaps t,he most eonspicuoris feature of the suprillittoral zoi?e, os'the ' shore just above high ~.deline, is tine blackr,es:. of' the island conglomerate induced by a heavy grov:th of blue-green dgae. Both Neritn mci Tectsrius up-

pear to feed by -ingestion of this blue-green algal natericl. l'ha animal3 iiv- ' -. ing directly or indirectly ufjon this materia!. v:ere to a large extent migratory. . . . . As discussed in greater de-tail in the floristic report on Myxophyta these blue-green algae appear to have several very important roles in the detercmina- tion of the nature of the edge of this isl cine! conglom&ate shore. Briefly, though one s~oul~consultthe sectl.cn c:entioned for the details, -these roles seem to be such as: softening of the limestone rock; iniiuckg rasping by the . snails; elevation of temperatures; protection of the rock from rain; protect,ion of the rock from the buffering actioin of sea water winileshifting LnG pH locally; and locally affecting the solu-Lion or deposition of c&ci.um carbonate through their metabo1ic'acti~iitj.e~.

~nsh&ev~a.rdover the' islund con&omerate the black line so sharply distinct at the sea edge of the islaid conglomerate in the aerial ~hotographs (Fig. 5) fades to a grqness over ",he exgosed surface of the -rock. %at, this is superficial was determined by breaking out fragments. The frapcnts were white where not previous:!y exposed to the light. Similarly tht: undersides of stories lodged o-. laying on -the surface of the islalid conglomerate vrwe grsiy on the exposed. surface, this faded to gqen just:under -their edges and %b.e remainder of the under s?:rfz.ce being white. For a df.scussion oi this phenomeron see under Entophgsalis-- in the section on Myxophyta.

The island conglomerate on the sea store of kIomohorno was a bench (Figs. 2G and 3) about two feet above high water line and sloped, ni.ti.1 ridges peral- lel t~othe see, somemhr.t towwd the i.sl.and mass. Yne Tectarius-- - opuletlon dwindled soon inshore of the seemrd edge of the rock ana there was nouiing found in the way of macroscopic life fcr a dj.stance of perhaps fifteen met&s. Inshore of this in crevi.ces, shaded p:iaces and under rocks for Liie approximately twenty meters of the more-inshore remaining portion of' tke exnosed island conglomerate whnhat was taken to be ;$elaranhe coccinea, a Littorine, wrr.s abund;mt. The same Ehtophysalis crustacea mas a'blmd~a~tin the regions vabere the litt,orine was abundant, dong xith ot'ner blue-green algae.,. but there ;?]as nothing else macroscopic in the way of living material other than tie ia.rger transient aninia1.s such as msn and birds.

B. Sea Bezch

At the seamrd extreme one sat7 only sand., 'a-b the landward extreme only bushes (Fig. 3). kt first glance, one is inclined to,distingui.sh to.~czones, one of beach and one of shrubs or bushes. . . The edge of. the vegetation on the Hoirohomcj trmsect sea shore is not what mas expected. There was no Iponioea p~--cawaeat all and Scaevoln frutescens, so cormon on sea beaches on atolls elsewhere, did not extqnd out onto the beach. Indeed, though a search ?!a& made for it, &GO pes-czi? %?as found on nei-ther Ra.ro5.a nor Takume. Superficially there appe~reda zone of sand as a gently sloping beEch extending inshore about 20 or25 meters and rising about two feet. This is, perhaps, the area of which Rm. 3. Taylor (Plants of Bikini 1950: 162) says "on the upper beach there mas nothing" in .the Nor%hex Marshalls Island areas he studied.

A vegetation of Surima maritima, Pempilis acidula and !;lesserschi@g z- etabordered this sand beach (Fig. 3) which mas apparently so barren of living things. However, the smdl tropical lizards we :mow as geckos were to be found under the larger rocks that. sat on the sand where its seamrd edge ran out onto low places in the isiand conglomera.te. Miiiute --.-Suriana plants were to be found in surprising abundance growing scattered about on this sand, but were only found upon c1.ose observation. .. The surface of the sand was a buffy white near the sea edge and more gray at the inshoreedge. It was indeed superficially apparently devoiii of life. However, around fo,~tpri.ntsin the sand, a pale green edge could be seen about two nli.llinkte&s under the apparently sterile surface. This proved to be a layer of blue-green clgae (largely Anacwtis -montana--- and Entophysdis crustacd two millimeters thick. mere seemed. to be little else in this sand :.mt,il one dug dovm about tvco more centimeters, where the sand was found to'be damp, and where one was COG fronted aith a maze of rootlets one to two mil-lim,et,ers in diameter. After digging one of Lhese for a half hour and follorving it many meters one of our helpers, Tetohu, was put at following tile root. After exposure, the irregulm. course of that p8.rtl.cular root was from within two'meters of the sand's seaward edge to the tree some forty-four meters away. From sampling of the sand area, it nas decided that the roots of this partic61ar tree, asserscknj& ar~len'tea,occupied all the nearby sand area. This led. to the postulation of root domimnce of Xesserschmidia over the many minute Suriana plmts. This &IS -.- - an amazing dominance of the area for tha roots spread over L.3 meters, radially, while the tree top was only &bout two or three meters at most in diameter and height. The depth and dis~eterof this ?act and disi;ance from .the base of this tree are given in Table 1. -.Table -1 Distaqce from Depth of root Diameter of root tree i.n meters in centimeters ---.--in centimeters

Temperatures in the sand were measured and the coolest area in the sand mas sone fern centinieters below the surface. The sand aas hotter at the surface and at about sea temperature below 'his level. Table 2 is a resume of temperatures measured at different depths in the beach where Messerschmidia---.- was growing. ... .

...... , Table 2 . . -- -

-Po sition of ,>~ermom~!~e_;~_bv1_1!

Air above sand : . Just covered with. sand Below the surface 2.5 cm . Below the surface 1.2.5 cm ...... Below the surface 21 cm Below the surface 120 cm (pushed into mall of 'well dug one day previous) . . Below the surface 90 cm (pushed. . . into mall of ?!all dug a few hours previous)

Temperature and related phenomenz. rnaybe significant in controlling suc-. cession in the sere leadine:- to what me :"in& on an atoli. islet. T?.us it is of interest to learn something of the te!i~pera.ti!res tderated by such pioneers zmong the bushe:: and trees as !$essersch@?&+, Suriana and ?3_m$;i:?..Accorcl:i.ng --. .-. - to Vim. H. Hathe-ay (personal discussio? i~esserschn~i.d&ii.-a:.y be the only tree- like plant to occur nati-vely on Canton in .the Phosriix grou-0.- ., It seeras likely that it may be the pioneer of this sortelsewnere as meli. Th.us we are prone to attach some significance i;o he 1ov:er temperat-mes found at about the level of the largest ----?!?esserschini.di.a roots. Certainly their significance, rs ce:Li. as the significance of silch factors as water (set ~.and)and oxygen should be taken into account in studies of root biology in such beaches 8,s this. Our appal-a.- tus, laboratory grade thermometers, did not justicy fyny more detailed study of this possibly very important aspect oL" the environment.

The vegetated area at E!omoho.mo and generally el~ey>fheretoo, ms bo-dered by what could be cal-led a bush zone. Actually extending over the bare ground between and even beyond tie bushes in some places was Heliotropiumanomaium but this was infrequent bere. The bush first found upon approach from -the sea v;as certain to be Suriana. It even extended ou-t onto the islaxid cng:!.omerate at the end of the island. It extended over the sand of the beach, often as plantlets only a centimeter to two in height, to the inland edge of tne sea shore island conglomerate (Fig. 3 and 5). In a'sbrt distance from the vegetational margin, but often this was hard to de.bermine, one vias certai:n to find Pemphis. Often a bush of Pemphis nould occur scrrounded by several Sushes of Suriana.

Inshore of the Suriana and Pemph5.s one often found an elmost exclusj.ve --a zone of Messerschmidia.-- Again the Messersclr?midia was diffased among these bushes or t'ne most seaward other large plants.

The observed relationship of these tr;o plants at Earoia appea.rs to contrast somewhat with the observations of Fosberg (Atoll Res. Bull. No. 23) and Hatheway (z.G. 16), but it may be t'na.t at Earoia the exposed c~n&onierate is a remnant exposed by hurricanes and the situations are only superficially comparable. Apparently --Suriana could develop under ratlier rigorous conditions, in the sand on the island conglomerate and tolerate the high temperatures, salt and 1.ack of water exyierienced in such iocatioi?.s. However, i.t did. not seem to be able to develop in the presence of viable roots of -.Xesserschmidia. -- .- .- In- deed,on the beach %*$ere%esserschmj,di~ ras present there was apt to be nc small nearby Suriana., only mature large plants. Thus, on the beach Suriana tended to be clumped separately from the &s~rschmidia..-- -- Since we rarely found Pemphis isolated by itself, we gathered the ir~~pressionthat perhaps it or the ==gs vrere not tolerant of the high temperatures of the open sand and island conglomera-ke and was, thus, not such a pioneer. Apparently, there was not -the antago- nism between Pemphis and Suriana roots and the -l-F.Pemphis may have been favored by the shade and lack of competition with &e~rschinidlaroots found in Suriana areas. . .

As the upper part of the beach mas reached the parti.cle size of the sand inweased to that of small pebb1.es (IRII!?I) and grsvel (KONAU KORZREU). At the sarne ,time, there was a chmge in color from-the buff color of the surfaces nearer the sea to grey and blackish near the trees. The color gas not uniform, however. In the shacle, as for exa~nplunder xshes, there was less darlkenlng and out in the open the sand was in piaces completely bound into a blackish cake by ~nto~hysaliscrustacea. The te:npera.ture here under .the midd~ysun was 13.5O C. jus-t uiider the algal mat. This was at least 1.2 meters hbove hj.gh ti.de line and far into the bush zone, thus, not one of the phenomena of beach rock formation, tilough perhaps related. Gr~ivelsand rocks in the sandy open areas ia the Suriana belt 'tend to be whiter on top than those from fcrther inshore and the sand between .them was greenish below as in the case of Yne beach sand. The coloring material ill all these cases seems to have been derived from Entophgsalis crustacea nith others, such as Calothrix scop~~lorum,Masti- --.-aocoleus --testarum and Fischerella ambigda, contributing lesser amounts. 't 't the inlxer edge of the bush zone on the seaward end of the profi1.e at Homohomo theye was vgap covered by gravel and then various areas of Niesser- schmidia and finally the next Lo be discussed zone of (bettarda. The barren rocks from justou~from.underthese trees and bushes are black-top;?ed in general. Again the blackening was algal, and again in this case, Entophysali~ ---crustacea and Calothrix scopulorum. An interesting variation of this situation was studied on the leeward (sea) side of the Guettarda. The further from the Guettarda, the lessblack the rocks. This appeared to be 1ike.the reverse of a rain shadow. Perhaps, it was due to the protection from mind and thus lessening of desiccation in the "rain shadowN. That it was not entirely an effect of exposure of the rock surface itself was indicated by the distribution of greenness on subsurface rocks. Under the blackened rocks lear the Guettarda, rock surfaces viere greenish to a depth of about seven centimetzs, about four centimeters halfway across the (ca. 15 nieter broad) area and only two centimeters a.t the seayiiard edge of the area, nhere the surface was but grey. Collections of these rocks were uniformly soaked in the 1.abortitory to make sure the color differences observed mere not due to immediately local field conditions. .. . . Messerschmi& argentea, where bushes or small trees were present, arbi- trarily was acceptedas the innermost limit of the sea bsach. The soil, such as it mas, was the blackened grave1,described above. This smaltree was in general most dense near the Guetta.rda forest boundary and less dense toward the beach where it was irregularly scattered as j.solated bushes. ; In this connection it is to be noted t'nat on the tran;ec:t area. at Karoia'i'i~Lsserschriiidia.. . ----.- not only sprouts readily from skumps but l.~yws:.rea.dilyfrom decuntient branch&~. The relationship betyeen thiszone aid. the next isdescribed &itit'ne &&La?&Eor- ...... est. ,, ...... ', , .:. I... ' .. . . , , ...... C. Guettarda us2 ...... The greatest eleyration of the-~oma:ndgatraimxt area was &out eight and a ha~ffeet abo.ve high viat,er line. In general. the trhnsect area was covered "v.jith,Guettarda snecioaa from just seaward of the highest part of the isiand to

, within pel'haps five or ten meters of the high tide line on the lagoon shore, or perhaps more truly almost to the :Lagoon shore hi.gi~,tifie, line. This area (Figs. 2G, 3, 5) is the area supporting coconuts ivhere pLanted. It should be noted that this area na.s a majn source of Guet;L;erda as st,ructural timber for houses, outriggers, etc. , in the vi$lag&. Homver, ihe :heconomic.s of Rarois ,. (see:i3+elsson in Atoll Research~u1i:etin!lo. 32) .is' another. chzpter and can

. ..net be taken up her?. Upon rare occasions bier,sVissh&i~ trees of relatively enormous si& (one : foot trunks and tops 25 fee-t higfl were found in t'le Ciuettarda fores-t. More often mere skeletons of such trees %ere found. Around trie edges of .the &&- tarda-- forest on the Horn&omo transect wh-ile investigatkg the soil under G&- tarda we found rotten prostrate stems of 1Viessersch;midia. These mere at a stage easily disintegrated by foot: si.milal.1~-rotten roots bound' t6em to the ground. Such &ems could be followed to-mrds the edge of the Guettaj-da +iclcet, a distance of over twenty feet, and as the stems were follower! .they became less rotten and finally alive and reveal-ed themselves to be the living though ~pl-os- trata trunks of the h4esserschmidia bushes that so tightly and characteristicall.y here underly and protrude from the edge of the Guettsrda vegetation. Undoubtedly the ~es$&sc&&&& is very intolerant of shading and it is this that results in its beachward displacement by Guettarda though the ?@sserscbmi~iagrows best inland'arrax' from the beaches. Furthermore, since the &eJ&rda is fur-';her from the ses $nore than from the ].agoon shore and only on the hi.ghest..ground one is led to tie conclusion that it is not very tolerant of skit w&t&. . .. .'I' The'l-arie leaves of Guettarda---- accumulate under the trees :f& a time, though there was little in the way of humus. Since they aremqped they ~$tenhold small poolsof rain water. Having constantly in mind the mosquito and e1eph.m- tiasis pSoblems of tho Society Islands (though these v:ei-e resnecti.vely, neg3.e- gibl6"~d..absent: at Saroia) a great many of these small pbols were investigated as possibLe .bpeeding places of the mosquitoes. No mosquito larvae were found in the large nurabel'of such pools looked at. Similarly %Sere seerned to be

lit.t& in .the way of pools formed by empty coconut husks or in the bracts of . . coconut 'inflorescences. .. .

' 'The profile(Fig. 2G) of the transect indica3es a .low spot in the center ' of the island. This corresponded to what was apparently a partially fil.led channel crossing the island mass and transect at this place. There was esseb tially little change in the vegetation other than a qua.nti.tative reduction though the rocks forming the soil r!ere larger here on the surface. The bottom . ., of this trough of gentle profile was covere2 with stones largely three to. eight 'inches in xajor diameter. A3.1 were heavily covered with algae (m- phrrsalis crustacea, Fischerel.l.g _saj.&a, and .-Schizo%hrix lo~igiarticulata 11292). Much of the gravel surface urider the. uore dersa s.tands of Gi.:e-Ltarda mas covered with leaves of t3j.s plant with occasions larger boulders (up to 2 feet in dj-aiiieter) protrudiiig through the leaf cover. The rocks at ground level, or perha.ps more properly gravels since iAey mere usually less than three inches in major dimensicin, were in these weas rratller barren as were t:r,e tops of the large? boulders protruding t;'irough the leaf cover. IIoo;ever, on tb,e vertical si.des of some o? tile larger rocks black ra,tiner nos.~,ocaceouslurnps ap?eared, probably due to ~Mac~stis'".7n&ns 3.1302 and 113C4 witii tk-e dgae apparent zearer the ground as bi-owner patches of this algae and Anacystis nontana, Schizothrg giusepoei, Ent.ophmalis crustacea., anc! Scytorieras crustecea, 11305. Ir: less shaded and less leaf covered regio~~s*he rc~ksforni-ng the surface layers of tie soil. the said had more in the way of d.i:$coiorat.ion 'by Cilothr2. wri.etina, -Fischerella ambixua 2 Ento~&q--. .5--- lis crustacba9 and a fu~gus(1.1299) but s-till t3e discoloration was notiing like that fmnd nesrer the shores.

The seavmrd beach consists of foraminiferiL sand at its seavard edge.. At the inshore edge it is coarser 2nd k~asauch :'i.ne graze1 ?n i.t. Just inside the bush zone on +,he ssavrard etge She sche may be bound by aa!.gal coating as . . described. Inside this region the sand is gcne as tnough ii;'had been mashed out of the gravel. The gravel -l.s coarser at this seamri'r edge a.nd becomes j.n- creasingly fine as t'ne lagoon shore is approe.ched. At leest there is, tcward the lagoon shcre, an increasing predominance of sand and smaller gravels; the 1-arger grevel is perhaps there too. ifowever, the sandy ma-terial tomrd Kne lagoon shora above high water line has a different appearance from that on the sea shore. This lagoon shore appears to be of cl.astii: niiiterial, largely broken coral frapents in the broadest sense. The foraminifera1 sand type is found. in abundance toward the center of the island lagoon shore and. below high tide 2-ine, but not tov:ard the end of t.he island and the channel P-hich separated the island across which our transect ran from the next island. In Figure 5 this chimge is indicated by the bZea,3th between the trees and dark intertidal zone.

The ssndier soil toward the lagoon shore was beset ritn pekbies closely placed on the .surface. Rue green alga of rather gelatinous ~onsistency(@&- physalis crustacea, Sshizothrix longiarticulata., !mac?rstis monSana, and &f- -tonema crustacea 11.302) coated the soil. Bikile grey at the surfzce below about a depth of about 2 mii!.im.eters, vihere not covered ;.:itfl pebbles or rocks, the sanc? is green down .to iibout the 2.5 centimter level. This a.ppears to be. sheath mtericl of Eymploca kieneri (?), Enlophysiii~crusti*cea and Scytcnema v--hofmannii (1.1285). The pebbles pihich cover the sandy soil in certain small discontinuous areas were'thoroughly algaleted. witin Scgtor~einahofi;>~~i~~~ =id Entophysa1i.s crustacea (11303) ,' of-ten so much so tkat they sppased bl.aclc.

Inshore cif the lagoor: st,orm rainps and around the neurest acg vell shorm (Fig. 2,occasional nearly buried stones nere exfoliating either fr~mi:atural causes or because fires had burned over -them. The exfoli.ated ckips Tiers uniformly covered. with such algae as 'Kntophvsa:.is crustace_a_, Fischerella aabiwa, Schizothrix loneiartlculata and Gc:r.tonc:na crustacea (11284) on their outer surfaces. Perhaps .these algae play some role in the breakdcwn of ].and 1e.id rocks, e. g. in "boringn into tne rocks snd inducing softening or ixxcreasing the rtater-permeability of the rock. Other rocks that protruded in an otnernise more or less hlga.1 sterile area of soil that had been bmned over Tere heavj.ly covered with Ihtophysa1i.g c~us~taee~~.,Scvtonema -~.r?stac.~&and &2ii7.0&h-ix misep7ei (1130.4). . In fact these viere the most heevi1.y e.lgnl-co'rered. rocks on the land. Rotten voody 3ebris 'f0'~nd.here was heavi1.y covered with E&t_cl+nna, -ocellatum (11297). The soil on the ~omohomotran'sect has been described in its superficial. aspects above. ' Humus could. be dis-tinguished toward, ,tb.e lagoon shore. Even toward the center of the profile in-'a sna1.l rather dense coconut grove an uppi- A-1 zone of ilumus cou2.d be distinbished in which the on3.y living thtngs detec- ted were fungus fil~ments(12.288) ada lower brom smd zone, an A-2 zone, or" little or no humus rrit'n the same fungus fil.ments (l.1287): Toward the sea the plants seemed to grow just as well $i.%o:~t. such humus, the surface being covered with the relatively coarse gra.ve1. described toa .dep.th of a foot or more. The geological members of %he party pointed out that this was very likely dile to the finer material having been washed cut by the hurricaxes. It was sugj

A considerable amount of time was spen.5 atte1fipt5ng to esttjmte the specific distributions of the various smul.ler p1.wts along the Iiomohcnio profile axd in Ynis transect area. The area ha2 apparerit.1~been burned ova- repeatedl:? throogh the years, with the various irregular burned areas averiapp5ng. This was both an advantage and a disadva~tagein aktempiing to devise tentative e~~ilamtions for the distributions observsd. Perhaps the most clear. observation wes tikat, Microso&u& scolopendria, the ever conmon Polypodium--:l.j?&e fern, was coextensive in range nith Guetttirda, often ggrv~i.ngon i't a16 aU oboi~tunder it. it seemed to grow as well with the coconuts.

Other plants were less clear in their roles an6 dis-Lriix~tion. Scae~rola --.---frutescens, which one normally expects on beac3es and the comrnon Fzstlorbi.a atoto, grew throughout the burned-over areas, xi ti^ the Eunhorb:ia apparen-t2.y P ---...... appearing first and perhaps being restricted to tne

1. Lagoon shore above kli~h tide line. On the lagoon beach (Figs. 3 and t 5 (betwen trees and first 1: i~oonvmrd- dark line)). , of the t,ransect area i." seemed clear that other .things beisg equal there :.oul.d be a condensed version of the transition froin Guettwda to Messerschmidia to the 3l~shesFenphis and --Suriana. However here local vari.ations in .ithe com~ositicmnnd form of the beach were more pronounced com:>aratively as this whole transition ageared to be restricted to a band about, five to fifteen meters broad. The la200n shore (Figs. 3 and 5) appeared here -to be one that was building up and extending into the 1.a.goon for there m8.s loose niaterial accumulated in front of the vegetation and an active reef below low ti.&e line. Messerschm-iclia was present, hov;ever, only near the end of the island.

Morphologically the surface covered by flovesing plants sloped gently toward the lagoon from an eieva%ion of about three f-et. This sxface ws rather Solidly of the ciastic sad and small gravels described above. 7ihil.e under the edge of the Guettarda or ilesserschmidia the grave1.s were b!.aclcish and tine sand dark grey, toward the lagoan the surfa.ce became iight,er grey. This v:as duo to a coat of Ea.s~ipmole.usteeetsrza and @touh!ysallis crustacea (11286). The individuzl pebbles are dariter on -their upward fscing surfaces with increasing prominence of &toneme hofmannii (~1.103) and lighter on their surfaces facing the lagoon ridges and facing do~vm.

The most inland rampart or lagoon beach ridge (i.3 is flnt topped and sloped uniformly down on both the l.mciward and seaward ftces. Tue top of the rampart is whitish in aspct and consists of mixed. greivels mostly sxaller than three centimeters in their largest di~ension. The lagoon facing side of this upper storm rampart above the whitened gravels belom high ,tide line are grey in gross aspect. Individual gravels are grey on their long exposed surface, brownish on their edges and greenish under -their edges, fading awzy to l-hite in the center if the lower surface is sufficiently 1a.rge. Such stones xere turned over just above high tide line and left in order to determine if tnis typically- grey coating v:ould appear during the approximately tv~omonths we were to be there. These stones remained in appearance quite as when turned over.

The top of this major lagoon beach rampart (Fig. 6) is as uniform a5 though it were a small man-made grade and is the principetl walkviay along the lagoon shore. Below the lagoonward base of this ranpart were tvio or three smaller ramparts of vjhitish gravels. The surfaces of these 2.5 cm minus gravels are harder than those of the grey gsavels above vhen tested viith a knife. It was observed that tkese gravels are worked over vigorously at tines of high ti&e coincident vith onshore ~Mdsat the lagoon shore. Thus it was concluaed that the a3.ga.e and any surfacessoftened by weathering are kept ground off. There was little in the bray of algae apparent here other than minute Lroim patches in cavities in some of the pebbles. Melaraphe, hovlever, is common to such lagoon rravellg beaches just above high tide level. . . 2 Lagoon i.ntertida1. shore:,, he' $xterti4al region (Fig. 3) of.the lagoon shore on: the Homohomo trarJsect'c6nsiits:of a gentle slope 3f centimeter-minus gravels about 3.2 meteis b&d. Its:&tent r:as :recagnizabj,e by the br~';mcolor induced by blue-green algae. It ,sp$ea?s as. e ria.rrow cJ;arlc iiregulw band L? Figure 5 in .the:trinsect area, the inner sharp margin of which is separn-i;ed from the trees by the light colored beach area. Away froin t!le end of the isLand the size of the gravels was mtich l&s,,~$lVVi.&. pdc~ migrated .back arid forth over it just landward of the usual %ash nf the waves as the tide rose fell...... Behind each embayment in the lobed lagoon reef the intertidal. area and lesser gravel. ramparts above it ?:ere conca7Je in form.

The only fishes seen here over this part of the shore vere mul.!.et at high tide. One red and bror'n shore crab w;s comi:.on here in the in.terti.da2 region. These crabs were often poised just outside the reach of Yne waves. The scien- tists and children delighted in their response to being tossedinto the water. The crab, hesitat,ing a moment and then orienting witti the wave moti.on, ivoul.d hurriedly scramble'back up on -the beach out gf tho water.

3. Lagson subtidal shore. Along the lagoon shore, except ~Aerethere mas a g~avel.bank opposite a channel. openir,g into the lagoon, there $?as a reef Lwr- dered by active cord animals. Th5.y reef shows as a iimar iiregiiiar dark area opposite the isl'and laeoon shores in ?igi.?re 5 between the iriterti.ile.1 regj.on and the lagoon bottom. For the sake of discussion this reef can be divided into a number of zones, enumerated here as "A" through '"GU and i.llustruted in Figure 6. They sre taken up here as they were most extsnsivelg s:tudied in conjunct tot^ wi.t'n our study of this transect.

Geographically and. morphologically "A" regions (Fig. 6A) are intertLda1, and have been described above.

"3" regions are very variable and consist of a coralline algal yalilieinent (Fig. 6B), coralline aI.ga1 nodu3.e~or gravels. If unconsolidated .Jhe "ti" regions consist of an even more gently sloping slope than cnpA"regions and are covered by gravels. Here, however, there are more small and more flat pieces and the gravel is cord. chunks covered with corallj.ne algae. '-Phis area %as six me%ers broad on the profile. Ot'ner "Ill ;arem to be noted are the m- lithon (11757) algal pavements which are qui.te flat (see below) in nature.

In this "R" area &raea obvelatau~asfoimd in association with the coralline algae. Latirus SE. mas found active on the rocks.at nigb.t in both the "D" :ad "C" zones. It was not found on the sea reef. Mulle-t on occasion swm over such areas as the "B" area and over the more lagoonward areas as well. Just below lor: tide line a holothuri.an was especially common in cavities in the coralline algal pavement and the coralline algae covered, fragment areas (Fig. 6B "N" and "0"). Under the rocks in this area is a white Isonomon along mith an -Arca (of the &. no~egroup (turkey feather ark shel.1~)). Perhaps here hypo- and epibioses should be considered separately. Most of the animals found here are hypobiotic. , .. W" regions are sand dominated flats (Fig. 6C) and are essentially the bottoms of reef pools. They show up in i7igure 5 as the lightest colored region on the lagoon reef. A few living corzls are found on rock chunks aith a fev! hblothurinns (1'1361, 11363). Ti1.i~region- on the' profile is about four meters broad. This is the deepest part of the'lagoon'reef flat, but rarely over a foot deep at low pool level here at Homohomo.

Often Haxicaries (a small wrass) hides imong ihhecorallh~enodules or Coralline covered rubble. Perhaps these fish are truly charaoter%ctic of this "C" region for the other fi.s&s seen here o~casioilallyare largely species much more abundant elsemhere. . .

While on tlle outer reef Strombus maculatus is co~l.mon iil the .s~.ndj.erparts of the pool channel region,. in the sandy--- pool region.or reef flat (Zone I%") of the lagoon shore lxo differrent species are common. These arc Strombus v?rs- --bilis and 2. gibberulus. gvariabilis is quits siniilar to 9. macul,a&~~dif- fering in having only obscure striati0r.s end .these jnly in the central portion of :the.outer lip. In. maculatus this strietioni&eather uniform and distinct allalong the yellowish outer 'iip. Conus tulim was collec-bed @.livein the deeper parts of the I1Cn region rih.ich vier?. in connection across to the sad beyond the reef edge' at about the "D" or "E" level, hocimntally spedcing. eburneus is found xith the two Strommhus species mentioned above. - .Beyo!ld the "C" area one stepped up'abwp%iyonto vrhut, ?re may call a "D" area (Fi.g. 6D) of dead coral the upper surface:: of which wre often silt covered. This area was 2 meters broad a.nd dominated by sandy patches, the cord occupying less area than th.e sand. In Figure 5 the Vt area is the light grey shoreward edge of the grey lagoon reef margin.

This was follorred by an ltE" zone (Fig. 6E) that vias essent;ially an e~gh.t meter belt of the sane Pocillapora (large!.y) as in the llD1l and folioxing "PI1 zones. Sand bottomed. areas betvieen patches of ---.PocJUopora are minor 5.3 area covered. Living Porites was found around the edge of each Poci_llopora- patch. The 'aspect was often that of the inside of a :nicroztoll top with small Tridacna specimens and a general. surface veneer of algal material. It !.s over this heavily llalgaltrtedll inner reef edge that ikanthurus t&oste,xus (the convict surgeon fish) is nost abundant. It does appear cormonly both inshorewmd and further offshore but in reduced numbers. It seems to feed on the non- calcareous algae that cover dead Pocillopora'branches nith a brovnish coating. Those algae are fine recis and Zonaria. Inthe sand-bottomed channels betmeen the Larger patches bcropora .?:as common but the heads viere small;

An "Ft' zone is to be distinguishes (Fig. ' 6F) as:a dmse mass c,f coral fhgers, again the sa-e Pocillopora, alive a.t leest on the lateral upper edges and not closed over at 'the surface. Hov;ever the tops were ~m~cer.?ciaith as- gae, often of fil.amentous Rhcdophyta. No said.: arc;as ore to be ssen in this three meter broad region. The spaces betvieen the coca1 anic~al.finfers were often plugged a fern inches dom with algal material, often Zomria or --EUli.pil.ia. FtnalLy .the very dark and narrow (Fig. 5) irregular edge of .the lagoon reef was distinguished as a '!G" area. Ehile about 0.5 meters broad (Fig. 5G) the living. coral was largely distinct heads on'the reef margin an*. gent& slop- .ing downwa.rd from the level of 'IF". There mas no algal veneer on the surface. In the corals here there was found an Anomia-like clam boring like aLithophaga. Leather urchins (related to the sea stars, Asteroid-ea, becanse of their ambi- lac-ral grooves) can be reported front here. On the reef patches theso vcere found further in from the reef margin; perhaps in &at is referred to as the D-zone above. Over the edge on protruding lobes of the lagoon reef the drop-off nrs vertical or even locally overhanging, but in einbayments in the reef tiire c'rop-off was at about forty-five degrees t,o the sand or sediment covered bo-ttom six to ten feet below.

The numbers or" hanthu~!]~mdP~ocontrus common inshore and on tog of tile lagoon reef are considerably reduced as one arops over the edge of the nearly vertical reef edge. This is ichthyologically the most varid habitat in the way of species and the most produc-tive in the way of numbers. Surgeon fisnes cruise along with the large parrot fishes audibly nipping off chilnks of coralline algae. Accompanying them are often various large wrasses rt:hich, wi;hi.le they feed with the parrot fishes, have small teeth and seem to search for invertebrates among the algae. Unlike the parot fishes,vihicki a1~1aysdash for open water or herd along the shore ?hen disturbed, -the wrasses inw hide in caves or under overhanging ledges. The surgeon fishes common in this area too cill hide in such places. They are frequently seen to snim along the face of .the reef above a cave or overhanging place and right on under the roof or iedge. The observer is bound to be somewhat disturbed by the picture of the several. different kinds of surgeon fishes then swimming along the overhanging surface wrong side up, 0' on their sides.

A cave fish fauna appears here of fishes which more or less conflnuously occupy these places in vrhich tine wrasses and,surgeon fishes merely hide. Most conspicuous of these are the brotulids am3 large sea basses. Along :.!i.til one of these sea basses there often moves a trumpet fish, an Au1osto;nus-,--.-. or E: F-- l*. l*. The unwary observer may sv:irn do%%to takre a close look at a brightly colored yellow trumpet fish am3 upon very close approech suddenly become amrs of the very large well tooth dark colored fish alongside which the trumpet fish was hiding. Often just at that moment one is inclined, though the sea 'bass are harmless, to go to the surface for air.

A perhaps even rcore interesting association of two fishes is seen i.n the case of a blenny and. the large parrot fish (TINCATINGA). Novc mos-t proper blennies are residents of the bottoms or piles of rubble, but this one accom- panies the parrot fish swimming in on odd leaping fashion, shomewlnat like a finch in flight. This blenny (commonly called a tick fish) is furthermore unusual in having broad longitudinal stripes of blue, bla.ck and mi;. Wen the parrot fish feeds the blenny presses alongside the parrot fish and clems off its larger companion's beak-like jaws, teeth and head arez..

In all there are more fish in the way of numbers and s?ecies liere than on all the o'tner parts of the lagoon end of the transec.i, put together.

The edge of the lagoon reef, the '!GI' areas, drop abruptly (Figs. 3 and 6) to the fine white gently sloping lagoon bo'ktom three to seven meters below. This lagoon bottom shows in figure 5 as a wlite area dotted with brownish (black in the figure) patches of coral and coral rubble. There mas little in the way of life on this white surface...... In tile sand bottom df th.ii region fj.6 rafely seen by others than ich- thyologists dominate. These are fish :hhi&h'are .quite pec.ul.iar to this region such 'as burrowing gobies and eels .(li:ciiidnidak,. ..,\ : h4oringuidae and Echelidae). Ia places of seclusion. in Coral r1;'ubl:e'k.e .infinr..small blennies and the young of

the larger wasses 'and of thlYvaria"s ' e&<, , qxh: as the unpleasant morays. Per- haps some. of the most chasacte?:lstj:c rbrins ,of the $~ol.e flat sand area are the lizard fishes. ., TUe wa%er area: of t~2sregion is: chayacterizeri by many kinds and large numbers of transient forms most: of. which +re apt to move out of the - area as one qproaches. Thi6 hahit'of. the'inhabitan-5s makes them difficult to obtain by any but very careful p~a&eii&&toffish pois.en,if they are to. be taker, . . 2. ..:. " . . . , ,, . at all by poisoning, ; . ,. ,... . , ...... ~. ..

The area.betvjeen t.he reef edge &id the ' first ilai;on ptch reef (Fig. 3H) is essentielly :a:chr;nnel frecperitedniar.. ... thg'ypper surface by the needle gars-

and.half beaks which are also coinnion to 'the areas fGrther lagoonward. , These forms a.re unusual Shorewai.d.of the r~efedge...... Fu@her dolwn in tine wzter cruise various sharks.. fin occasional, r&ra causes the sy:iqming observer to look...... around nervously for its normal and more ~oraci,~usshark buddy. Nearer the '.': bottom characteristically there cruise'carangias and large lutjonids. . . , . One of themore ludicrbus ic~~hjdlpgj.c.&~:~ionaersayaiiable to the 'swimhing observer in this area is ]la.h$&IX a 'smal.~.biacXand rihite fish of the Porno-' cen'cxidae. This fish swims i.n school.s.abibqut the occasional. branched cora:. heads at. the .bottom 62 Cne reef edp and out on t'le fine satid bottom. Wen .' sane danger is anticiprted, &s froin.,a suddenly' thrust outward set of :fingers.L . 1 on an am, the whole school daskes &to the seclus~.,on:of,. ,,.. .the branched coral.. .. . mass onlyto drift out almost togkthor in a 'few seconds cautiq~~slyandready to . . .< sink into the coral should the pretended d%g$.r still ,thl.cqten. :: -. . ... - ~ . , . . .. . , i :, .. Along the vertical. face of & coral patch& and i&&n ..&ios.e:-reef ther'e is a bright blue small (4 cm long) fish, Ciirowis, ri?~i:ch'ig spa11 schools be-. .... haves in. sornevihat the sane manner; but is more Venturesome. ..g? tkhg as n:uch, as six or eight meters out in the lagoon. , .. . .,. :,: ' A considertttion of the c'.is+,ribu.tion of varj.a+,iois 011 $he. la.goon reef as ' . one ]high-t see them from the zir (Fig. 5) i.s most valuable here. :;is. seen from .: this Figure 5 the lagoon reef is.not a regular band along the shore cut, a series of irregular lobes with, in the transect area, the lagoon face flatteneci and .the flat fa.ce -tending to face tKe win&. 011e of -tk:ese is diag,~ammatical.ly illustrated 'botil in pmfi.1.e and as seen from above in Figure 6. This same lobe shows in Figure 5 as tine third 'from the north en& of the. island. L%en a very 'brief stud:^ of th&e regioix and the reef in tlie lagoon reveals great similarity between the two. The individual lobes of the lagoon. shore reef may best be considered as patch reefs of wk!.ick3tke islend snore forms one edge. lis one goee toward an ernbayinent betwen such shore-bound patch reefs, or lobes of the lagcon reef, tinere is a conspicuous: change Fiepnding u2on; :iih.eLher one is moving toward the end of the ishnd (md the chanael there) or alorg the shore toward the island seoter. The "C" areas ase.essential.1~sepwate pools and in line with t!?e riind induced su~fatecu&wtk these 'd&n .out,topard the center of the island lagoon shoreover wh& r+=4en$iall,y ;a ikYt area.. The . . "C" area is closer to this down current edge of 'the shore ~oundpatch reef, e. g., here the 91D't, W, VTtand tlG1t areas are Earrower or absent, The "A" ahd. "GI1 regions were the most: consistent ii cqmposition and general character. The other areas varied roidely from place to place, and cannot be characterized by any single. profile study. In all positions in reference to these shore bound patch reefs the "A" zone ?emains appoximately .the same except for the change in particle size noted., Thenos$ conspicuous difference is in the qualitative character oT that region termed. here "B". At upcurrent sides of the'reef patch (Fig. 68 'lOli) the "Btl area is largely coral fregmeri-ts covered with a coralline algal coating (11357 (but also see 11352)) and there are many holothurians between these fragments. Even further upstream, or be- Itween adjacent shore bound reef patches, there is a pavement (Fig. 6B ";:I") of coralline algal material (11364) just below low pool level.. Tnis pa.ven1ent i.s about one meter or a meter and a half wide and nearly horizontal. Ilsually bordering this pavement on its offshore side ald domistream side was an area (Fig. 6B "Nu) of close-lying coralline algal nodules (Porolithon 1.1366, 11365 and 11364). In Figure 5 the lagoonviarc! margin of this pavement shows as a very faint dark line across tine shore edge of the second reef lobe south from tne channel north of' the transect area. Usually dvcr the upstream "D" and "C" areas there was 'a $nk sandy layer over the '%b3s of fragrr.exts, coral heads ad n~icroatollsthat may be the same corallino algae (11361) as tinat forming the pavement in the "BIJ area, but very mch less ne:Ll developed. . . Algae were found, further, under stones inthe "CIr arecrs where they were usually forms such as completely prostrate crustose aonnelia species and Eotocarpoid species such us (11353, perhaps really from llB" sandy areas). Spots of Sphacellaria were obtained here as well. Apparently such algae form the food for certain of the fi.shes, but no exacting food chains were vior?r,ed out. &ioil&, probably JZ. geppii Taylor, was hommon both under such boulders in the "C" zone and between the phalanges of the Pocillogora of more lagoonward. areas "D" to "F". This species seemed active in trapping and binding smd in crevices and holes and may play an active role 3.n solidifying of the reef material below the surface: the corallines being far more active, hoviever, thm Rhipilia right at the surface, Zonariq species, again, play a role if nothjag else in overgrowing the sides of the coral animals and perhaps killing them'by cutting off their food supply.

Along the lagoon shore further from vhere the active reef is near shore, that is near the center of the island shore =here the I1A" and Yitl areas are sandy and indistinguishable from the "C" areas, there are little sandy points upon occasion. These (Fig. 5) are usualLy in Line with reef edge configura- tions or beach rock outliers or other offshore features. me bi;ses of these poin"c while sandy themselves are often accompanied on each side by patches of (11351 (see $so 11350)). Where fuftner offshore the consolidated reef flat was not. . so strongly overlain by sand there was n coating of Gelidium (11029) everyvhere. Characteristic tufts of Lrnrrbya maduscula end Ca~ilerpa serrulata (11010) are about the only macrosco@ically recognizable subtidal a].- gae on the lagoon shores otherwise. Above low tide line on rocks are recognizable'what appeared to be Ectocarpus jgdicus and sorne of the little ubiquitous but' almost unidentifiable tropical Ibteromorpha species. . . Only about ten species of fish were to be found fron~the high tide line to the outer edge of the shore reef. This is n generally non-fishy area. Over the coral edge of the shore reef or as one approaches the edge there is a great increase in the number of the Little (10 cm) biack Pomocentrus nieriems which with its head protruding from almost eech ho1.e in the coral greet3 the observer mith a pair of very cold da.rk eyes. This small four-inch fish is common in fewer numbers ou-tward and doml over the fwe of -the reef as well.

T'O avoid needLess repetition of observations lhe differences between the seven transect areas studied are recorled below in one series of sections rat'ner the nutting in descriptions of each transect area. The 1oca'sj.on of these a.reas arid the profiles through ,them may be found in the iii.agrans, figures L .and 2.

Sea Silore A- - P Animal coral was not a. conspicuous elemeat enywhere visib2.e from the surface of the reef. In general the Village or Raze raefs vere the sea reefs having tine mgst coelentrates on t,hem. Tile sea reefs of other areas ?ad far fewer. Nowhere were they apparently dcrn:mant and .'.eai?i.ng to increase in mass of the reef 'flat or reef margin; %hisseemed to be

1. Spurs and Grooves. Flying just offshore along the v!iindp?ard reef from Kaea to Tahuna Maru provided the only op:~ortunity of seeing much of the !:in& nard spurs and grooves. Occasional. fleeting observations were r.ade from the top of the algal ridge bu-t these gave us at best but a quditative appraisal. The reef flat, perhaps in correletior. r:i'th the higher geceral surf level, seeaed higher in elevation than that on the lee si.de of the atoll. The spurs in our photogrephs and from t"e shore at Tahuna Pkru and Kaea appeared to be re2.ativel.y broad and flaL. Often they appeared to be narroxed toward thsir inshore end and thus the grooves between widened. They pitched on a rather even slope into the sea from the seaward e2ge of the algal ridge. Eetween the lowest wave trough 1.e;rels aerial. photogra~hsintiicate a rather rough and broken pasture of snail coral knolls and very irregular channels.

The view obta.ined by swimning Sea~ral.6.dmn the gradually widening grooves was very different on the sea shore of Notufano ('kkerau), Homohomo (Fig. 5) and Oneroa. In these latter places at least far f~fi$ yards seavmrd the grooves gradually ?!iidened and deepenhd. The surface of the spurs seemed -&a be sloping more steeply than tile floors of the grooves. This gave the impression that these tv!o fea-tures wouid bl.ecd into a cord. plane a, fey; hundred yards off silore.

'Ehile little sampling was feasible, the su:-faces of the grooves and spurs everywhere seenmere pink as though covered by ~orolithon. CertainPy those of Tokerau, Xaro and. the village area ifivestigated by svi:immiog were covered by this genus. In a very few places PociU~~orawas found on the inshore tops of the ridges below low tide line. ' V&ile altiost all .the P_i~ol;thon, observed appeared to be P. onLkrd%eg in one place on a 'idge top below low ti.de lice e. specimen of g. aeguinoctiale Gas obtained. T'nis is an iriteresting record, thc;ugk ccnsidered anomalous z-b the time, for this speci.es appears t,o be a dminant species in sisiilar. alAeasat Johriston Island (No-~eltyshoal).

At G.ake and in a fen other places the spurs in actdktion to 2. onkodes had &?jpkdroa, (.11@8) on them if their shoremrd end aae broad. Thcre are rare patches oi^.poorly developed g. ?pardneri (13.485) on these ?:id&es and whzt appears to be Me same species stillmorepoorlg. develoyad occurs beiiind (insidej the algal ridge.

The surge chamels in places extend through .Lhe first of %he rir'ges of "beach rock.I1 In places they are very broad (iOM) beheen .?he algal. ridge and the exposed. island conglomerate a,!& they are ca 2 to lMyl.Zeep. Their bottorns are scoured 'out ride p!.aces have cora1.s in them. Coral were not conspic~ious othervise on this transect area. Esscn ti.al2.y the sme sitxation prevailed at Kaea, &t here the al.ja1 ridge was less oftm cut th~oughby the grooves. The grooves themselves left us rrith the irS~pressionof being eha!.lorer and. mme nu3- erous,.and from the aerial photogragls, nore irregular in their courses.

2. Jlgal Ridge. The reef rXge area ms defined on the pr~file,IS the surfaces of the reef margin a'cove lon pool level.. The rj.dge as a whole protruding from the pool botconi level mi&% be ail at leaet equ,-li;i useful unit. ATt is felt that at Gammaoa, the leve!. of the reef ric?ge lj.ne md tni upper level of the boring urchir'.~or the sc-~.wardedge el' the Amphiroa zone (Fig. 2Ej is at the base of %y reef ridge that may exist as def'ined in the field. Perhaps tbe pool impounded by a well developed algal ridge changes tb-e habitat so ns to fa-. vor .the urchlns which seem to be the most active agerrts i.n destroyinp es$ecial.ly the inshore edge of t:?e algal ridge.

At Gake, and Gagieroa there seened to be a so-ce.l.!.ed I! backridge troughw rather than the flat.Pxahiroc zone recogniznble elsexhere (~'ig.3) at Raroie.. This vies often true elsewhere in Kereteki and to aomc extei1.k ic.t Gake, Takume. This sserns to inply that perhaps the reef ri.&e. should be defined as tile sea- via.rd raised area on the reef which' impounds a poo:~ muld gives the reef L.at t.he characteristics of a -tidepoo?..

As one proceeds along the reef ridge at Gavari.vari (Fig. 11, the general level of the to:, of' the reef ridge changes. CentraLly nlorg the ie!.md shora on the profile (Fig. 2A) the ridge mas abc~t30 cm big5 (ahcve low pool level). That, opposj-te tie northern half of the islami, vhile not shcLrply lower than opposite tke southern k.alif is ahout a foot lower. %is lozer resf ri6ge is more thoroughly "algalate<" from its pool edge to beion j.ts se6wu-d e&e. Still from, a distance it is unifornlly pink -in appea.rmce. .. . . The. outer half of the 2a.varivar.i reef riA$e i.:, ccvered !vi%'n -P. -.--onkoc!es (11926). IJicrodic-&on_ okeaurae and a fine &:a s..are. charwterisiic epi- phytes on the 2. onkodcs. A Laurencia-like alga (1.1326) is coinlnnn i.n small hollovs and holes. The more eroded iriner half of the ridge is higher than Vne outer half and appears to be more actively covered (11925) by non-calcareo~is dgae at the surzace them by z. @:odss. ,&xaasd%r~sa (11927) and C. 9- ritiana (=927) were found on the inshore slope of tine reef ridge dom to within 15 cm of the pool level. The genus @pi was repressnted by numbers of -I). ---morum ancl . u.Many veni~etids(11919 = J.?,E..M. 2221) were seen., . It seemed that even -Turbo setosawus inuch more cornlaon on these inshore sl-opes. The latter delightfully comesti3l.e species as :/!ell as the purely scieritifically interes.ting species were not.searched. ,for di2igent:ly on the seanard slope of the reef ridge for the usual reasons applicable to research on windward reefs. . . The higher reef ri.dge generally'opposite'tr,e sou.ch helf of Gavarivari, was in correlation with solcewhat diffe~entappearace. The inshore half of this ridge was yellow brown in color. This coloration is given by what appears to be blue green algae, at least in part Ri-n~laria-uo!_y.o%is --- (ll919j on erect s~~ines of rock left by the erosion of the ridge n:a-terial. In pl.accs the algal coating is sufficiently developed to. look not unlike th2.t coverirg the sortietimes siaiilar spines of rock just above the pool level at the inshore side of the reef flat or inshore !nargi-,s of the reef pool.

There was little or no general algai cover oi tne rock here. The only 8.1- gal materials at all comnon were isolatcd tufts of a $,&c&s&a~k~i;a and a &!&rod-ich-on (11919). On the larger -shells bnd dead Vermetus shells there wers obvioGsly fine algae but these farms did not cover to such an extent that the ridge appeared to be dominated by non-cal-,araous a1.gz.e (an2 di.fferent species were involved) as on the inshore part, of the reef ridge further north at Cavarivari.

Similarly there s:ere few living animals in sight. --Druna --ricinus and Druoa morum were found only on reef ridge pot hole bottoms end on their sides.

Low on the inshore edge of the ridge the reef is pink v:i-th various algae, but predoinlnantly 2. o~kodes. (km?hi.roa (1L917) is not a meadow hereabouts but, is found in frequent patches or tufts irregu1.a~l.y txo to four centimeters across. This is the only area on the atoll where Csntroceros was recognized in the fieid as a consistent do~ninantand these areas were sr;iall. bright, red pa5ches of uniform a;Jpearance. Sau~enciaforrned skimpy coatings an6 sma.11 tufts in tke hol- lows and. holes of the general g. onkodes cover.

The seawsrd half of the higher ridge area is, ai, inost, perhaps 9 to i2 centimeters lower than the inshore half. This outer reef area war- bright pink in area and a pr'iori-qpsared to be a suitable area for tho surf dwellYng P. gardneri and related forms. However', in no place at Gavarivari or Gagieroa was there any trace of 1.iving Poro1i.thon ~ardnerior similar specis. On Gavari- va~i,however, were found the greatest concentra.l;ion of bouldez's in the isiwd structure ~hichwere fossil remnants of. such species.

One "clump" of rchat, a.ppeared to be g. aeuuinoctj.&~ mas lost when pried loose in a surge cnannel bottom. Turbo se.t.osa was common on this higher ridge aselsemhere. No living Cypraeas were ssen on this higher pert ol the ridge either on the inshore or offshore half. A medium sized dead verinetid (11.919 = J.P.E.M. 2220) was abundant coiled fiat on the reef ridge pavement. It .was different. . from the vermetiol (11927) on the lov~erreef further norYi...... The d'gal ridge at Gake (Flg. 2E) has- large (25 cm) pita that are inter- preted as vidence of erosion by solu-tion;*The outer high part has fine algae (Laurencia 11.487, llA.91) and arches or domes of g. g@;gLde_s: (11/,8.5). The algal ridgeat Gagieroa %as not only pitted on top bu-tit appemer? a:: .tl~.ou$i it had been a sether high ridge now tr!~ricate,dby erosion..

, : In general as ihe Gatumaoa village area was approadied from G*=kethrough Tokerau the algal ridge becane less ridge-like and more of a cuesta. While still more. often'little other than a cuesta, as oile proceeded south~ia.rdto Oneroa a ridge was often present. This ridge when present ;?as vwy.oftm clef?- iy pitted on the inshore side by holes often occuoLed by peiicil urchins. There wcs little algal cover in such pla.ces beyond a generai p5nk calcareous coaklng thkeil to be undevelopec! 2. onkodes.

The sea resf in froni; of Tetou is.21? and 2Cj is covered :!ii.t? non- calcareous filaxentous algae. Wkile it sc'eins to possess an imp-emf-re nlgnl ridge the only calcareocs alg8 in sight that appea1.s dive is ;. fine Jania In- termixed with tine non-calcareou s f i.l,.anientou s algae.

As one proglesses along this iG&ge noF3x~ardthere we some c1ea.r b;t inconspicuous changes seen. First~y,there. is ni i'.ncrea.sliie abuiid.auce of '~_~JLO~S.& pennata (5n 11851-11852) until it for:~sccns~j.ci:c;us t.irfs o.f a square mete? or so in area. This .tb..~tng:;raduai.iy hecam less corisp>.cuuus ax& a brenciied roa-:ted --Cedium (11860) becane common only to dSsqqpear as t3cr.e cone in-ho prominence in turn Neomeris (11857 etc.). tlhile a:t fkst fourld only in !>ole~,a tenth of a. kilometer further on it lS~edmas? 'af $he larger cavity rj.ms. Tiiis s?ecies was smiil an? ringen and when smali hardly celcj.fied. 1; half kLlometes i'crther along the Coaum was gme and Keoneris scarce. %er, a IXck,vosphaezia (I cell -.- -- is thick and hol1.0~)became common. , At about this point al.i~~ost3 km. north or' Tetou, there nere the beginriings of a ,coris~icuo~sdispiay of 2. pl&gr~Ier; (~!.553). This mas first seen around low aciges of ixcurrent channels, but fur-kher on, it extendeti to local algal ridge prominence&. ' The P. onkodes ?!as riever conspicuo.Gs though and possibly because of eitrene ercsion here it was on its way ogt (i. e. here there was inere1.y a. less dea2 Porolithon ridge th:m C5rect.Q opptisite the village of Tet'ou) . One kilorxeter so11Lh of Tetou .the algal ridge has g. onlmdes (lldi6) sho~r- ing in about the same degree as 2 or 3 kilometers norih descri.bed above.

At Kaea the reef ridge area anb more seaward arws ;'.-.-A pink vii.& 2. %I&- des. Turbo setosa T?as common. Little else was visible. In one ti?? -6% despeesh - 7- of tk.e excurrent channels through the a1,cal ridge a fe?: coelenterste corals nere to be seen; none 7ia.s seen on -the reef Slat, 2k.e algal rid~eor e;seu:nere. The algal ridge (Fig. 20) 8as slope? very geztly icto the pool on ths ree:f flat. d fev: miles south, at Tetou, the reef rid.ge vas inuch the highes-t seen and there covered with e coating of non-calcareous algae and shsrply distl.nct Train tile reef flat area. Heye at Kaea the inxard edge of the algal ricige area wn.s ilard to locate because of tile gen'cle even dope and the la.olc of macroscopica:~..lydis- tinct indicator organisms. The rather urliforrnly nigh edge ?!as cut into from the seamard race by numerous low surge cnmneis, on!q a ver;. :Few of rkiich extended through.

+' &onsidered by Newell to be mainly an effect of gravel scour. E~J At Mataira and in the same geographic area of Talcume Atoll the margin of the reef gradually sloped upward reseinbling "Reef type IT-B-(1)" at Bikini as depicted Sy Trzcey in his figure 1 (Btl2.l. Geol. Soc. her. 59, 1948). Here likewise iqrere found the only godd cases of grooves exbending into the reef flat and overgrown at tine surface to any ex-ten't;. One of tnese into which we cou1.d dive Qras perhaps 20 meters long, five meters deep md from 0.1 to 2 meters broad.

3. Reef flat. The reef flat (Fig. 3) is considered to be a tidepool bi- otically related to the sublittoral region. Tke sea.ward edge of the black coating of blue-green algae seen in aeri.al photographs is the inshore margin. This margin is broken (Fig. j) by the complete channe:i.s between the islands. The seaward wall of this pool is the alga?. ridge.

The ilarrorv heads of grooves freguently extcnd from the sea tlirough. tkis wall on t'he mindrrard shore. These are, tinen, rela-Led to small localized excus- rent areas. More generalized larger excurrent e.re8.i.s connect the reef pool to the sea as the village pass area are apwoached. It may be the single pass rather than the ieewardness of the vill.age aree that is responsible for this difference in connection behieen reef flat and sea on t;?o windward end leeward shores.

At Gavarivari -:here is no division of the reef fla%into Amphiroa, or bring urchi.n zone, etc. The whole reef flat is characterized by the lightly sanded pink pavement and black holo

In this zone at, Tetou, just inside the reef ridge S~&plocahydnoides was found. as soft wisps with gelatinous centers.

At Gavarivari the 'inner part of the reef fiat was distir,ct froin :what has been describe6 above bs the pool area. Under rocks neer -the shore edge of. tinis al.ea are many large boul.ders 30 to 100 centimeters in diameter and usua.lly. ?a- ther thin proportionally. Under these there is an aggregation of small gravel and even sand. Thesenarticles were found to be variously cemented to the large boulders, to the reef pavement, and to each. other. These shaded surfaces are often; coated green and opten supported various non-calcareous algae (11925) which seem.to be but poor c',evelop~~entsof those species found on the reef margin or algal ridge.

As knimj~s'perhaps the most abundant macroscopical.ly was. Morula prmuiat_a (& .. -tuberculata in TTiner's very useful book). i)rider. rocks was a variety of smull ;.Cerithium-like gastropods among which Planax&? &o~&u_s- was the most common of these "smaller than usual collecting size" shells. One shell of Morula uva ......

(called M. in Tinker's book) wan obtabed. One. sh+l of I;Rb&ri~ia, punc- , . , -tata %as found. This was unusually plain white butthe uppertwe had. the vio- , ,. Let anterior tip to the colimellar surface character'ist'ic oftbis species. . One small specimen, about one centimeter' long, of -Czus inQ,il~r;.is mas found under cl stone. The above six mol3.uscs (MD 11923) are in the 'U. S. Ii'&tional Kuseum under the nurnber JPENi 2218. . .

Locally near. the shore at ~avarivariand Ga&ieroa. . Lh~ewere c:i~,stersof -Chama hdf-sbellsprotruding from the reef pavement. ... No living _C:EI~ vrese seen here. Few of the other characteristic animaLs of ,such r&gions xere seen alive. For example, after some searching, a few @n& sx,ons&j;b: wre seen but. of the shells found only one was alive. Fern other gast1'0pod.s were ?ourid hers (11923). . .

Drupa grossulariz, common in leeward reef pool zones at Ruroia r,as not found at all on the windriard reefs of Raroia. This species .was -.is0 uncomliion on the windwclrd reefs at Bikini, only abouta half dozen specimens being found according to iV!orrison. As hermit houses (12.931 - SP94 2222) @rr% hu_fmLi-..,xhs'is j~ippocmta~;wm, -Vasum sp., Strombus gibberulus, 2. mutabilis mere conunon. 80-6h Stronjbus gi+ berulus and 2. mutabilis normally at Earoiu are lagoon speciinen bu-t Gorrisoa found that at ~kiniS. mutabilis occurs ~ithS, maculatus on th* sea. reef flat. -- - -- .- -. - w, 'I'ectarius, ~Grita,&?ithiurn, Polici, Morula and Mltra- --littera-:a .. - --. oc- . , cui-red. The last four, whi!..e hermits, are cha.racterisfic v;hen Give of tne in- s!lore ~ortionof .the reef pool area. CC,!TTta~_j~.u_~ an6 Ke&f!zL are characteristic of the shore between tides or above the tides in the case' of Tecf,arilis. -Vasm and Bursa are pr.obab2.y charxteristic of tile more seeward goo!. areas. : On both the ?Wtairn (Figs. 1 and 2F) and the Fake (Figs'. 1 and 2E) tronsect areas the inshore edge of tb.e reef fl.at was, in genera!. more sh-rllow than Vne outer part. The bottom near high tide line was con;?;loi!ierate ro-k :.$it>large shallox pits on the surface. In these there rras very often a flrkkezed. stone. As the observer moved seaward these pits mere more and i!!ore frequenZy fused . . forming chains of pools th-rough >-;;hichthe.vra$er drained as tht pol level low ered. Toward the seaward edge of tine systom the walls 'cf the iniioiciual pools gradually were red~cedto merely sharp pinnacles a decimeter or t~ohigh. Ai; Niataira, these disappeared about halfway across the reef fla-t. The outer part of the reef being smooth to its sea margin. . . Lt Gake the inner half is so irreguXar in e1.evntion tkaJ., one h6s the effect of a series of incomplete small reef pools 25 to 60 cri~ in di.amet?r. The, bottoms tend to display the reef pool charecteri8tics of beirjg covere2 with a' fine coating of sand and what is taken to be juveniie ercrus-Ling corailine d.- gae. On this bottom there wJere to be found mariy specimens of such species as the Strombus maculatus, =us ebraeus and 2. sponsalis characteris-tic of th~ pool area of the sea end of the Gavarivari transect. ~nonet,a aid some of the characteristic Drup_a species (and 2..~r6ssularia as hermit she2.l~)::.ere also seen. The walls of these pools and the loy~stqf the ridges by .t;nci.r color and general appearance seemed to represent the .. s,hore. betmeen high tick level 2nd lon . . pool level. .. . In contrast almost the whole reef flat at Kaea was a. pool zone ~*:ithlittle other thaii a smooth coating of coralline algse visible. At Kaea there ?me many relatively small reef boulders, but they were not as numerous as they were at Gavarivari &ere there were larger ones o.s well.,

4. Intertidal and 'nave-wet Shore. This area is aivisj.ble in general into a lower yellow zone and an upper black zone. The juncti~nbetneeil t2iemv;as considered after observation to be high tide line. In general on s0ii.d shores tile intertidal or yellow zone was a gently sloping consolidated shore about 20 or 30 cefltimeters high an6 two meters broad. The black zone above wac. usually a precipitous droi, of' 1.15 centimeters (Mataira, Fig. 2F) or so over the edge of a oonsollda-bed rock bench (PAKOKOTA). The black zone also extended as a coafag inshore over the upper surface of this bench for a variab1.e dia-tarice.

At Kaea (Fig. 2D) this yellow i.n-ter-tidal zone was largely cmted (11.900) vith Ento~hysaliscrustacea and Plectmeina nostoc~rum. At Tetou (Figs. 2B and C) this yellow zone was coated. with the same Ent.ophysS?1ifiand in addition ---Calothrix a.em&nin (11321). At Tetou the yellow zone rocks were in places covered by a fine brom fuzz (11322).

On the transect a?ea at Gake ?,he walls of the poo1.s dominating the shoreward part of the reef Slaty-otruded. from the low pool level. aater surface. The a1ga.e (114.83), &tophysai.-is crustacea7 Xivularia yolyotis, Plectonema nos- tocorum, Calothrix scopuloru~and 5. $rustaceas coat -tiis protruding rock a yellow bi-own. Thus, these protrudhg points anu pool v:al.l.s mere listed as intertidal. The presence of: a fel-: specimens of & hipnocastanem as hermit homes on the pooi bottoms and the presence of 3orula gran~~latasupport this hpo- thesis. The bottoins of these pools were the sandy pink of reef pool areas.

On the Oneroa tsansect (Pigs. 3. and 2H, I, J), rciiile there i4?as no specific or definite "high tFde line" fish fauna otherwise at ~taroia,there vas in the splash region on the reef boulders a species of blenny during lorn tide periods. This blenny was loath to return tothe aquatic environment even when disturbed. Perhaps tne restriction of this fish to such a region is sm indication of a different species of algal food though a priori it might as well be some other restrictive factor.

The fauna in the intertidal regions was perhaps richest in the village area (Garumaoa) and poorest at Oneroa. Gake held an intermediate position, for example, the blennies and gob& were tnose of the above stations, but some species were absent...i. e. the fauna was attentuated from that at Garu- maoa but richer tha! Oneroa, both in reference to nuabers and s;?ecies. No fish mere found intertidal-ly in the Geke sea reef region other than the common white spotted rather innocuous Gmaxp_jlc& wkich moves in and out with the tide as did Acanthurus triosteiius. However, rare this eel nas, it was definitely more aggressive or curious here and at Kaea. It ~ouldfollow a passerby and go so far as to hump its nose into a proffered shoe sole before scurrying for a rock to hide. At Gake none of the "spl.ash zone" blennies could be found. On bolder sea and channel shores a sea slug (Onchidium-- sp.) and a greenish half-shelled tectibranch are to be found in the lower part of the intertidal area above the pool level near shore. Wnile seen only at Oneroa and Garumaoa it is presumed that these two occur in similar places dl around the atoll. -33- A.t Nataira (Fig. 2F) tne large pits of the reef pool gave my to small pits with reistively blant topped walls in the intertidal zone. These were the sizes thought borsd by the resident gast'opud :;peci.es. Above high -tide ].he, in the black zone, the wall tops on these holes were harper.

Above high tide line the black or spray zo~ien,ay be reeognimA by its color when dry. On Oneroa. (Fig. 2Ii and I) thicr was largely dgal material (l1675), -Entophvsalis crustacea and %>chytrichia -2, that is dayk br6?ki v7rhen 11:et. Here at Raroia (L1675), in Nlamichuse-hts (7273) arid in the Phi1ippi:~es(10937) and elsewhere this Brachvtrichia xPpearsjust above high tide Line, cften xith the ecologically reltited Cal.oth-ix species.

Three phenomena are notable in relatior. to the ."bl.ack zone". lj At cflata-- ira there were numerous pools of fcesh vieter on the surface, often aiaut for-ty centineters broad azld four to six cen.Lj.meters deep. These wre fresh w~terat the time of observation, though within teri meters of the sea eclge of the rock platform. 2) :Zany large reef frag~r.sntsg.,up -to 100 ccSic meters in sj.ze, vere strem on the rock platfoi-m. here. Sme had several '!.:i.nds (s'?j~j~is pol-ypa.r-~pa.raks, Portulaca. johnii, Poerhavia dlffusa, &llGs~&xna;?orr,Li~) of fj.o:eririg plan% growing on them. Inshore fr~meach there extende6a bar of smal:: gravel. 3) From the sea edge the platfo1.m so sloped docn '-Lowar.3 the la~ovnthat it v;oz!ld have about reached the lagoon level at the lagoon shore. at tk.e sea edge of %he unconsolidated island material t,he surface of, the ~:atfoiin.:;as lereled ad foulid to be 30 cm lower thaa the sea edge. Tfl% slo~e as c&mo?d.y, but not always, observed in other areasof iieroia,

The highest protrusions of the inshore reef fat pcol v;alLs at Ga'Ke, often only the size of a fist, ab0v.e a certain level were cclored bi0.ck. Suck black "algal" material was colie'cted (111&) and proved to be &it,ophysaI.is ~,rcstzcea, --Rivularia poiyotis and Plectonema nost,ocorum. This same black alga:!. material, predominantly lbbhysalis crustacea 2nd Ca2.othrix scop~lorum(l:!.~!.j3), ccvered the so-called spray weLzone (Pig. 3) on both the beach koalders and gravel .(Ehtophysalis crustacea alone 114.37) near the shore. This ms accepted as evi- .dence that these protruqLons were in essence above high tide line.

The blackness of the black zoze at Tetou (11318, 11320) fs a coathg, in addition to t'he dominated Entophgsalis cr-us.~~aa,coi;ipo:;ed of c-a&o:t&ri.x ]:ilosa., -C. scopulorum, Mastigoco1.e~~tes-tilrum, and Flectmema tmebrari?.. At Gnke only a few specfmens of N&.& were seen; too few to decide ul~on their zonal affinities. Tectarius mas observed only on tiin Leach boul.ders,in the qper part of the black zone. IPne shore was a grave?, ridge and this nature of the shore in tiie verticul range of tnis species (mi:perhaps ,as well as Nerita) might be cause for the apparent absence of the species there. Much of -lash zone gravel. is v!hite at X-ie sza!;:ard foot of %fie i,iizh gravel ramps, . .. ..this .. probably Cue to movement with each wave th{t wa.siies' high...... <...... -. . . . An interesting habit.was notkd &davarivai ma. else~kiere;, among the hermi.t crabs. One is puzzled by local accumulations, ofted of one species of empty gastropod shell. Often these are of but one size. They ape fcund on rocks a few centimeters above high tide likel. There were %&iy such accumuln- t'ions at Gavarivari. But here it was found tinat mny of the shells had hermit

.. . , . . . . crab occupants and many of these were a~srtureside up. just &at the e~lzma- tion is is not clear, but it did seem that the hermits ha6. crawled up themselves, perhaps Just to sun themselves. It j.s fo be noted in passing that the common red lan2 hermit crabs similarly accumulate.

The black zone at Gavarivari (E:ig. 2A) m.d Kaea (Fig. 2D) 5.s very broad. and the surface, whSe plane, slopes gently toward the high Lide level down about severity centiriieters; The gre;r beackl-rock fla,t inshore is essentially level. The black zone here icstead of be3g essentially the outer edge of a consolidated beach rock pl.atforn as usual, is ccimaosed largely of loose and semi-cemerlted-.in--placef1a.t stones embedded in sand, each of wh5ch ti1.t~into the sea. The 51ackene6 rn?Lterial (11928) appears to 5e Eri+ophys&& ~ms+,as:ea. The stories tend to be green around their sand enbedded bases and on their urider- surfaces when l2ose. The vrhole is 2ppa.renYiy seated on a cmsolidste2 piatform of homsgeneous rock at about the pool charnel bottom level. This is revealed in the exposure of such material in the freqcent small pools in this blaclc region. The basement rock, though, instead of being pink and sanded o-ver as 5.n the pool. chanrel is blueish and rakher clean. The 'ciueishness 5.s about the same blueish color as that to be seen around snail bor:ags in the blbclr zone, for exarple, in the PAIIOKOTB 6:. the sea end of the Garumaoa transeci. A% Kaea much of this boulder covered flat extended up ", levels where the rock was only grey.

While their shells were fourid elserhere ng 1.i-vic?g Tecta:rius, l?erj.ta or Welaraphe were found at Gavua--ivari; though a hrief fruitless seaxh was made for th.em. Tectarius was fcmd 4.5 feet, above the pool level on the reef boulders though and these specimens (li931) mere turned in to iiflorrison (J2lW 2222) for identification. Various gast.ropod and pelecypod shells (1.1971 = JIWd 2222) were found in this region and on them were various small algue !11930). Gn the rocks et and just above the high water level were found (11932; RjvuLaria polyotis along with the ubiquitous aiysalis crusta.ce5.

Above high tide line in the black zone at Mataire and also at Gneroa (Fig. 21) exfolie.tion was comon. The exfoliated pieces coming off were frnm a. few centimeters to almost a meter across. Exfoliation was noted elsewhere a!.ong the lee atoll shore but was not recorded. from the windr;ard shre.

AtGake and occasionally elsewhere on njndrrard or exposed shores the bl.ack zone was bordered inshore by a gravel ramyiart. These were most interesting. The sea facing base of the gravel rampart was filled vit' sand. %is san.d in the uppermost part of hhe blaclc zone was bmnd by Mastip:oi:oI1eus testarum, w- tonema terebrans and, as nligiit be expected, Entophysa3.i~ crustacea (1.144.6). This growth was permeated by numerous :?ungus filaments. Flst areas of Seach- rock seaward of the gravel r,mparts, where these curvkd shoreward at, their ends, were often covered by fine sediment bound ilto pinkish crusts. These were qu.ite stony when nearly dry. The alga naterial (ll4..36) which v!as the bSol.ogical. part of these crusts was largely Sizothrix longiarticu%a.ta., ihto;;hysa.lis crys- -tacea and Calothrix scouulorum. . . 5. Spray-wet shore and sea ramparts. Arbitr?rily the' areas (Fig. 3) be- - . tween the algally blackened. spray wet reg5.m and the vegetated sreas are biologically treated llere as "sea beaches." These tiiffeyed gret;-t!.y in nature from place to place from loose gravel ramparts to bo~ilderfields to congl.merated rock benches bordered shoreward by sand or fine grzvel. In .%heaerial photographs (e. g. Fig. 5) the be=ches appszr v~hite, soinetimes dotted wj.th black in- dications of shrubs. The rock benches appear As radially st~iatedgreyed areas just shoreward of the black zone.

In the Tetm and. Gake trznsect areas the sea beaches wre gravel. ramparts a$ their sewaard ed~es. This rias also true of the more southe,n norc exposed ends of Garumaoa and some of tne larger islands in RWO. AS an exam!?!.e no.te the successive profiles 5, I and H in figures 2 and 9 of Oneroa. Figure 23 represents the profile at the exposed part, the tend, of island. Figure I1 a mid region further north. Figure 2E a profile a.cross the northern p:cot+cted end of the island. As this series 7i;as passed. through (Kg. 3) the s-?a beach became less gravelly an6 at the seawar6 eige it became a ccnglomerate bench . . (PAKOKOTA) . The top of the gravel ridges, or rai,npart,s, every-vhese j.s grqr and %?ere was (excep-t at Tet,ou) only a gently curving slope jnshore .to the t~ee-covered area.. The whole beach area was clominated by unconso:Lida~edgrey gravel to inshore areas ,where ---SnriLana became dominant. Only one f1wt;ering plan-t w!as ever found on the gravel ramparts. This was Ipo!noe% tuba at, Te-tov. The local. peo- ple insisted tha-t some of these trailing plants haa blue flovers but r~oneother than the typical I.tuba rfas seen. Ipomoea @a-cagrae was not found on eitker ~aroiaor Takume and a special search ras made for it.

Soutn of Tetou at Gasieroa and Gavarivwi, a Large amount of the sea beach was small (25 to 50 cm) boulders. These were cemented at lev-er leneis o;ito the consolidated platform aescribed above. At higher levels they cere loose. A large proportion of those ( e. g. llP1+5) fzr inshore had the a.ppear&rice of a ----Porolithon of the g. flar6neri typ. No such forms were seen on 'the reef margin even after repeated search. Such algal boulders were no-t at all conspicuous on the lee shores (Tokerau, the village area, or Karoj.

The black zone organisins spead over tie consolidate6 bench !PXGXI!TA) to variable distance shoreward. Splash from wares mas seen to wet this arca upon occasion. Curing rains the area is washe& q~itefree of salt and small.pods of fresh water accumulate (determined by taste). In ti?.;. vic3.nit.y of \he sea edge these pools last noticeably loriger tha those formed furtinner inlend where the PAKOKOTA is merely grey. .,fihetker this is due to greater porosi-ty of the rock, higher temperat,ures or lower k.urnid;t,y or ,some other cause as the sea edge is 'left behind was not determined. The floor of the poo2.s near the sea e6ge at Mataira were coat,ed by a black soft scum cdiled XOPAI;;. (l1372, Xothrix scoau- a B. & F., Entophgsalis crustacea (J. Ag.) Dr. & D., Anacysti.3 dimicll.ata (Kutz.) Dr. & D., Schizoth-ix &acust.risZom.) or a fl0etir.g soft mat. Around the pools at the landl~ardedge (0 in fig. 9) of the beach rock, at Sneroa, the surface was grey when dry -and black when net iAth E~~+.op:'iysal~~siista~sa. T!le blackish coloration of the alga found on seaward edges of Yne rock surface (R in Fig. 9) was the ubiquitous ~ntonhysaliscrus-Lacea and q.uo:~i. Occasional boulders on the &>rewere sonetimes sufficiently large that land vegetation occurred. on them. At Mataira one such boulder attracted attention in particu1a.r. It was about ii.ve meters high, six, meters 'vide at right angles to the shore md six or. seven mcters long. This boulder (XOMAU TORDJ) ~vasat least 3-00 meters inshore from the reel edge. It, i~sthave takn a tre- mendous wave +,o break j.t out of th9 reef edge ar~dcarry it up that far. On its gray top t'nere was growing Tlmonius, =1&aan&ss, '~i~~~o.$i.~mw~omalu~,Portu1ac.g johnii ,ad Boerhavia diffusa. k most odd observation via.s that. the upper half of this boulder appeared to be composed of Pocillopora faced up-lard and the lower half of Poroiithon onkodes faced do~~nward.Eowhere did anyone on the team see either of these organisms growing in any other position -",an ffacing upward. .. . 'Niiile no loose gravel was seen on tne sea edge of the PAIWKOTA or in the 111 . Vain pools", further icsnore increasing amounts of loose gravel appear. liilS gravel is in general or" smaller size as one procee2s shoremrd. Nearest the sea it wa.s almost all either on pool bottom or in bars benind large boulders. Inshore it formed a general litter obscuring the surface of the PAKOKCTA, e. e. at Meta-ira.

At Gavarivari there was &n exteensl.ve bhck-zone bo~;!.de? f-i.eld extending up, inshore~~ard,in-to the grey zone or PXOKOTA levels. At Xaea the simj.lar koul-- der field was much more in the grey zorie. These boulders mere found in varying degrees of cementation to the solid reef ma-terial. Perhaps if covered by smd they could have become cemented into -:he island corig!.on:erate be~chesseen. These benches where we saw them mere exposed by hurricaaes ripping the vegetation axd much of the islands av1a33.

B. Sea Beach

The veget,ational margins and.the sanay"are&s between tie spray zone PAKO- KOTA (isl.and conglor~ieratejarid trees seen to be related. This v;as decided . after f* s.Ludy of root areas at. Homok;.omo. In general E'einnhis asidula and S.uri- -ana maritima %?erethe plants Qssoci~tedwlt'h PAKOWTA areas and Messerschmidia appe&red with the presence of: sand.

If the present extensively &x20sed island conglomerate was at one time productive land, Yoen about ten times as rr.uch pro&~ct!.ve iand was prese??t at one time at Ra,roia. Local. history records a great deal of destruction of iand but ve do not know how much. A re3uction of the human popula.tion by a factor of ten is related in the history correla5ed nith European civilization of the area.

There was little to be found in t:?e vmy of sea beach 'biotic elements on the PAKOKOTA other tli,m for ~moccasional brlstie-l3ke tuft of the grass, tepturus repens. kt 'i'etou Wtwus ---rei:iens appeared on both the PMOKOTA .axid the sand. As at Homohomo and etch place where this point ~asinvestigated the sand for the first three millinieturs b5io~:'the top one millimeter of ?-!hit- ish sand is greenish near the sea. edge of the beach (Fig. 91) nith various blue-green algae. However since they cannot be distinguished even as to genus with the unaided eye and because some of .%inem grow well further seaward they do not serve as indicator organisms. Nhile at first glance the sea beach seemed to be rather barren, close in- vestiga-tion always revealed roots or seedlings or the tufts of Lepturus or other plants (in one case geckos) and this seavmrd limit of sush macrossopically recognizable biotic elerrients became accepted as the soamrd limit of the sea beach beyond which mas the spray met zone. This mas essentieliy true also .?;t Oneroa where Peii~hisand Suriana became cfomlnant. Dnder the Penphis i.n partica- ---a- 1a.r the sand is solid and well ;>acked, i. e. not the 1.008~sand of the sea . . beaches. Prom the seavard edge of the bushes, some 45 meters from the beach . ~ ,rock where the sand was less packed to tile k.shore edge of %he tjusiies essen- * tially the same blue-green algae were round as :::ere ?om6 at .tile sea eGge ~f the beach. This seemed to indicate there to be no red, dj.fferince iil tile silr- face soil conditlons between what might be cal.led. the smdy beach and tiie bijsh- covered areas. . .

At Tetou Ipomoea. tub+ was al.so found groxing a.t tiie edze of the 3-uett.arda. areaon the sand and often growing as a clirnber into 'cus;:es of --Pei.:phis,.- -- -.--Suriaaa and young Guettarda. The largest pa-tch, about 20 meters l.ong and L, ;mters broad, occupied the inner surface :ma tor, of the grh- el. rmpart iLlust,rated in Figure 2E. T'fiis was the only thing like tine expectei? pox-i;h of 2. p&cxrrag seen on Raroia.. 'I.tuba is apparently the on1.y species to be found; th:iug.h o?JT local resident assistant thought this particular prjtcil of -.----S;>ornoea to be blue flovered until show differently.

The bristle-like Le~~Lurusbecame abmdat inshore and Ecrima becaine more frequent and larger until it dornlnsted tile landscape st r,ietou. --

Wile &sserschmid& was .common at the landward edge, on3 indeed on one profile it was conspic~~ousat the ou.ter edge of the "ian2" behind ,the glevcl ranpart (Figure 2C) it was not ;?ha% one coulc call a strong element in tile pop-- ulation from a purely observational standpoint. Inlard one can dra~on a map an arbitrary line between the seamrd edge of 'the Guettavfk. and the inlaud edge of the bush zone coordinately dominate< here by 3urimaaand Pe2his...- Or,e element (Hibiscus-- tiliaceus var. ststis?, 11833) found 0nl.g- a-:-?etou appei;red 5.n a very narrow zone just seaward of the Guc-ttarda. This specizs wae a ~LIF~ usually just less than two meters tall wCt,h rather stiffly erect or patent' branches. It was interesting to note that the young, more +,eminel, leaves nilted at a much greater rate than the oid ieave~...~dto note also that the leaves apparently did not remain on tpie sterns very long. This was evj.denced by their appearance in clusters a-t the tj.ps arid the great frequency of ieaves at the bases of these clusters 75th "autumaln foliage solora.tio3, as well as the accumulatioi~of leaves on the ground.

It should. be noted. tha: [email protected] is to thelocal pecple a very valuable mulch forming plant. In this concection it was no'ted that leaves of --Sur- -iana and Temphis accumulate to B.considerable degree under tkeir res:~ective bushes.' Along with the leaves of the above --Hibiscus these are all proSably very active plants in the humification of gravel pla$forms such as th.at here at Tetou inasmuch as humus is formed.

With the region outlined to the seaward by the Uibiscus n-t Tetou and by the bristly form of Lepturus, the ground is covered by stones (5 cm) that are blackened (Mastiaocoleus tsstarum and $~tophysalis~crustacea, 11877). On . ., transects elsewhere than at Tetou one cm3.d expect a coinciden5e if the suc- cessful. coconut plnntings end outer, seaward limi-t, of Gue-b*,arcJ.a. I? windward areas under the ---Ouettarda there vias li4;t:Le !Sghorbia atok or.&caevo?.a fmtescens in comparison to otbr areas shidied. llhese, two pl3;lts were Far more abundant on the leerard side of >the lagoon. SimiLarly on and beneath tile coconut trees Microsorium and mosses were corniiion in v;iridwrd ireas but cot am abundmtly so as on the leewarci side of the a-Loll...... As in the case of cti-ier islands along the rindward side of the atoll Gavarivari displayed (Fig. %A) a. broad area 'tjet~;eenthe vegetated area md the sea. There were also several. gravel rainparts in tkestructure cf the seaward part of the vegetated area separated from the lagoonward gravel. ramps by low areas most of which were srmrpy. The more seaward grave:! ramps (Fig. 1) tend to be strongly covered by gravel that is coarser than tn8.t covers their seaxml uppermost and lateral (exterior) faces.

Various of the islets north of Teto>~were investigated as to t,heir flora. Lepturus repecs and --.Heliotr&_m gnomahm appeared alone on many of the islets that were k,ardly more than sand splts. "7~bese irere Cie snallest vegetated islets at Raroia. On islets that had a fair cover of these $ants there were coconut'trees but nothing else was to be seen in the way ~f flo7::ering plants.

There seemed little transition betwe?. islets having tne aforementioned vegetation and those hhvir~gadditiondly =his-9 Suriana, arid Cuettarda.-..-. - Eon- ever, there were a number of flats v:hich were Little otber than -...--Tsmphis-Suriana --- -thickets without Guettarda. This .Latter genus appea.red only on islets ri'riere there were elevations distinctly higher tk,ar the usual levels at vhich ?ein;)his and Suriana were to be found.

It 'appears that these beech edge plants are thus pioneers arid that a ~re.ter supply'is a.vailable under their cover that will at least su~portm. kc2 is planted. Since -Cocos does not bear and do vrell in the above places it is not normally Flanted in regions supporting only the %esserschid& sera1 stage. 1%car6e postulated that tna reason for the absence of iuiesserschmidia from such islands at Raroia is the length of -time required for Xessem.cj~midiato becomedistributed to such areas, germinate and grow naturally.

~ A preliminary assumption,is that- will grow in sand with little or no humus if there is a satisfactory water supply. Similarly, it may be that Guettarda, Wkich seems to follow Nesserschmidia, requires t'ne water suitable to -.Cocos but in addition more soil or shade during develo'prnent of its,younger stages. The absence of Guettarda seedlings in some of the burned Guetlzrda areas at Opakea substantiates this. Perhaps Nesserschmidia growth sets the stage, serally, for Guettnrda. . .

Kaea (Fig. 2D) presented another case, of Suriana and -..-Penphis, and also ---Tirnonius ~olyparnus, on Lhe island congl.omexate and bed+ gravels. I!edyotis rornanzoffiensis was there too, but as most common it mas more conspicuous as . : . , the channel shores of the island were tipproached...... : ...... , . C. Guettarda Forest ...... , . Skeletons of large Messerschmidia tress ('7 meters tkll) were found on Ku------A .kiria. At Opakea (Figs. 1 and 2~rincentral regions relztively 2ecentl.y dc- stroyed by fire, among the skeletons of fire-killed. Guetiarue,, seedlings of M-serschmidia had appeared in profusion. At Garumaoa and generally elsewhere Guettarda appeared on islands, on the sea side, about 2.2 iN abovehigh tide line. That it does occur lower, for example, was observable at, Oneroa (Fig. 9) where on the lagoon shore, one trunk was based on the sand &oping :to tb.e .. water's edge. It was perhaps a foot above high tide line, .but .dead . roo% protruded into the sea water of the. lagoon at high tide.

The Homohomo transect area, uponwhich so much time was spent, was a very muchly disturbed area and not so desirabLa for an a~alys5.sof the vegetation as Oneroa. Oneroa too is a coconut plantation, but, it is an old one in which somewhat of a balance between the pre-plantation conriitions and pim-i;a.tion cox]- ditions may have become established, andit appeared to be typical of what ne found in coconut plantstions at Racoia. Three profiles across this area were leveled with a hand level and pace&, These three profiles vere through & exposed part of the particular isiand (see figure lJ), through a moderately exposed part of tne island (Figure 11) and through the lemt exposed part, that is the part most protected from windward influences (Figure 1H). These profiles are illvstrated in detail in Figure 9. A sample of the distributions of the species ,can be had by stud.y of Pic;ure 9 and reference to the speci.es found at each of the locations indicated by the letters A through R. The relative abundance of the species is indicated by its position in tne lhts of species... the most abundant being given first. The taxonomy.and certain speciric information on these organisms is given in Atnll Research Bulletins No. 33 and 34......

Fine sand dominates the sea edge of'the Cocos- area at Oneroa and this j.s largely covered by algae (Fig. 9G) binding it into stony moss-lilce txfts. Surianaand other bushes appeared with the most seaward coconuts at Oneroa. The coconuts had been planted further seaward here th& they are usually planted, and the most seaward trees had not developed well and not seem to bear nuts. In this area (Figure 9F) at one or more places fragmentary channels shovi as depressions in the surface of the island. In these depressions sometimes &- -iana dominated. The sand under the shr*.ubswas either covered with a layer of Suriana leaves or the complament of algae indicated in Figure 9 at F. These algae form an almost continuous series of dark lumps, 0.5 to 1 cm. in diameter, over the surface. Further toward tlre center of the island and at higher elevations (Figure 9P) boulders of 1/3 to 1/2 !neter in diameter mere frequent. These were quite black ontheir upper surfaces xhen wet but only plain grey when dry. This algal layer of Symploca kieneri and Schizothrix (?) longiarticu, -lata mas particularly developed in surface depressions on the boulders and diminished on parts mpre exposed to tne air. 1Xhile 've did not turn over the . . ' . 13rger boulders thesmaller rocks and gravel. near the center of the island tended to be more completely white beneath and grey on top, or blackish if wet. 0. They had the same com~lementof algae- (see list on Fieure- 9 for N and -z though----" not listed some Schizothrix longiarticulata and Nostoc muscorum was present at this latter site) as found on similar gravels on the lagoon storm ramparts (beach ridges), md a more or less green line around the margin of their white under surfaces. Toviard tine cen-ter of the island the surface is in general buff gray and while the sand and enall gravel.^ are not bmnr! t,>gether or cemented they are certainly well packed. After a ra3n dgae (figure 9E) cause these same surfaces to become. greenish.

At Gavarlvari, Guettarda a2peared on the nearly level top of the outermost ramp and contjcriued on all. but the lowest areas across the island. Even on the outermost ramp some of these were as much as 0.6 meter or norti thick toward the base belov~the majcr limbs. Most of these large Guettardda trees had light grey bark. Our n!e.asuremen,ts indicate about 920 hectares of G~et%a.rd& forest area on the atoll about 560 of it planted to coconuts.

The trees on tile seaward edge of the wgetation a.t 're-Lou were cozted on their windward fsces nith Trente-ia (11842). This green alga formed a bright yellow orange coa.ting or1 the %Fee trunks and. limbs as it does elsewhere in the world in such ha.bitats. Tne larger limbs of Guet-tarda. on this seavjard face were coatred beneath nith a whitish coating of funguu mateie!.al (13.S41).

Morinda &tri.fol.ia was mosS often more abundant just viithin the edge of ---Guettai-cia areas. It did. occur at &.ru~?aoe.rarely oilkside this cover on the seaward side of the island in a muchly disturbe?. area. Gn the atoll of knaa, it simil.arly v!as seen seawari? of the major tree covered area on a raised area. It was most fzeyvently seen dong the lagoon shore, but one ususlly v~:ilked near the lagoon shore or along the algal ridge. There is no ceritral road or, in fact, much of any reguiar trails at all at Raroiii. At Tetou within the seaward edge of the --.-Guettarda area ';here is m unusual anount of %orin& and this extends, large17 as seedlings witnout much in the -;:ay of brmcning sad less than 3 meters tall, to "xl' in Figure 2C where they stop rntner abruptly. Grass in this area is only spotty and the soil is largelv obscured by the grey algal- coated small gravel (11876) discussed above. Mcirir~daseei:,ed to be well able to gron in the shade but only away from the wit water. In tn.; southern Kar- shail-s, Morinda is about the only tree reputed to survive Artocarpus seem to grow under the dense shade of Artocarpuu (breadfruit). -,-- well only far away from szt water at Raroia.

Special note should. be nade of tne hermit crabs (keriobita brevinianus and perlatvs)-- found on the kighest parts of the islands. One comes u;?on fifty a hundred clustered about the base of a single tree and there rnj.11 be no others in sight for fifty mef,ers or so in any direction. The tree is sane-times a small one or an odd one. One aggregation at Gavariveri :'!a$ on .the ground around where a. downwa~dgrowing Guettarda limb, touciled the gronnd. %e liab then curved upward. so that it touched the ground only in this orie place. In the occasionally occupied villages these same hermit crabs may accumulate almost entirely in jus-t one of the abandoned. houses. A htuman occu?ant, if wise, will confine ail nis dec2.pod contenders for the period. of residency to a bucket or box.. .thro!i-ing them ou-:, of the house only being the stimulus setting them in motion to a noisy return.

In passing, it should be noted thct Eirrus &ro,, the coconut crab, mas a highly prized article of food found rarely in unpopulated Guetta&. areas. The only specimen shot was from KaAogi where it was molesting a Pandanus fruit. This island was just north or' the pass, and was an isierld visited infrequently. It had the only large Pj.sonia trees seen at Raroia. . . Pandanus was a most vari.ab?.e mtity in form; In habi'tat it, was found on the highest parts of. the islan3s. Usual.ly it was sum0undec! by -Guetta.rda. However, some of the sii~all,yet highest, j..sian& such 'as Kaei or1 the mindward side of the atoll and Te%ari, just south of the pass, had th.is tree gro~ingin exposed situations. At Gavarivari &pAga occurred on some of the !sigh w;.nd.- ward ramparts and was therequite improtecteG by o-thez. vege-tsticn. The trees in this habitat vere nearly a solid leaf-filled masses adthus most typical in ' appearance. . , Though little such land was ave.ili;.ble for study the coeonbts mere 3.11 gen-- eral not growing abnve a level.(c?etermined with a %and level) of 3.2 meters above high tide !.ine. 'The surfaces aimve such ieve3.s vwe of comae gra~reland occasional flattfsh boulders (up to 0.75 meters iz diameter). Essentially it j.s in the -----Guettzrda. area tiat most a2.l the flo~~eringplant species are to be found. . The aerial. pkiotogrz.phs ~el:ill.ustrsrte the extent of this area on the individual islands. This is tile stippled area o:i the map accompanying the report by Uevrell on the geological. nc~ka-t Raroia. In going from Garumaoa northwar6 towmd Geks the :Clara in gencrel becane increasicgiy depauperate; though the ge~cralsi-kiuaSioa as dascribsd for the Carumaoa trmsect area persists. After leavi~gEIomhurno one can alniast wimt each individual tree of any species othe~tkan ---2Cocos Gr-etiarh__i,.2.-.> Messerschmidia, Pemp'?is acidula and. Suriana mari'ti.ma.

Scaevola frutescen~~nowhere at Raroia greiv o-~tontn the beaches as i.t does in Hawaii, in the Marshalls and elsea~lere. As a rule it ?:as a plant of the inland --Guettarda dominated end areas but appeased to be much more intolqrant of shacle. Then growing in the shade Scaavo:La develop& as a vine~pl-ant vcith slender parts and creamy flowers having no purple wavy petal edge or co~olla 'base.

Euphorbia n'coto seemed to be more shade tol.erm-t thm Scasvola arid was the predominant herb (isolated and usuaily approximately 30 cm tall) in most coconut groves. It likevise may either have a shallower root system or be more tolerant of sa.1-t th'm Scaevo1.a for it extended. nearer the lagoon and oPxn nearer the l~urricane-disturbedisland ends than did other members of the ----Guettarda forest communit:~ and even Scaevo1.a.

While discussing shade it should be pointed out that under the -Cocos and --Gue-ttarda cover there were usually rilany smal.:. saplings o? Guettarda. The pos- sibil-ity that these might shoot up quickly and fill an opni~g---in the forest canopy comes to mind.

At Raroia it was Suriana ma.ritlma rather than Pernuhis ~cir'~ul+that seemed the most haray pi.oneer form on sand and rock. "Iis is in con-tra.st to reports from other atolls and it nay be that at Raroia this apparently unusual situation was due to the hurricane-dishrbed ~latureof the northern part of the village area where this relationship nas observed. In some places at Oneroa (Fig. 9) Suriana did grow in abunda.nce well inl-and on a smdy area as described above. Inophyllum _calophyllum was present only as a single small tree at Vai- tuke outside the village, Garumaoa. In the village aroa only one bree of &rcl&- -ta, a smd.1 one, vim found. This was at Kumekume. FIorLh 9f the pa:% on Kopuano there was one w,a small tree along the southe~~nedge of tl3e coconuts not far from the :*rater in the channel. On another island, also call.ed Kopuano, the name essentially of the estate to which it be?.onged, were tvo rattler large Cordia trees . . -- (TOU) and many small. ones forming a sm:lll. gmve.

On Kakiogi the largest Piso.2ia-- - grandis,.-. -- .. GATAE, was seen. D.is vias sonie 0.8 meters in dianeter (but not PB~I) and foilrtben inetirs hi#,. There are several trees just slightiiy smaller. and. many very mial.1 trees. It, ths, appears that this species was rep-oducing. Though there were no guisio de7osi.t~identified on the ground there were red-footed boobies nestj.ng in the trees. Terns similar3.y made the area their home. One tr+e abut 3.3 of a meter in diameter was Zound in the easte~,npart of the Gake region. At Ftioaroa there mas one other -.-Pisonia (1.1505). No reproductj.on of tbj.s ttee at Pa.par~awas seen axd neither bird nes-LE nor g~iianop?e:ce seen to be as:;ociatcd with it or its environs. No seeds were to be found though flowex %ere coll.xted. Ex- cept for perhaps a dozen or so trees of urdform size nitfi smali oiies underneath at Opakca no other Pisonias mere found.

Vfi~ileraye, eouth cf the pass, except in the villkge, Lei~i~diuin.bid.enta%um was scattered along t:?e islands to the nortn. Ikrc it. was withered beyond the fruiting stage or juvenile, no fruits or florrers being seen. C)n the winrio;ard si.de of the atoll fruits and f'lw!er.s nere couunon, e. g. at Kaea. --Tinionius poIymmus was rere north of the village to the pass. One plant beiig found 5n Tomogagie and two on 'I'akeke. North of tine pass tkis si~ecieswas coininon; as it was in Eiaro and Kereteki.

Hedyotis romanzoffiensis, like Tiions 'was most commonly fou?(i. aicmg the channel ends of islmds, the fo:mer often oil rather thinly covered conso?.idated roclc aqd tlie'latter usually on the more gravelly soils. ikd~tis-- ras found occasionally in widely different. fcms. As a vine it resulted i'l t:u;Xes near the sea beach at Oneroa and near the lagoon beacil formed rather tall spin2ly plants. %ese two vi-th the bushy plants c.f islad ends ?were so different that they were thought at first to be different species.

North of tile pass mosses and ferns scon became insignificant an? were not found at all from Mataira -through -;he Gako area.

Such ;,lants as ~leuryaruderalis gre1:J tn proFueion on some o,? the long un- disturbed Guetta~daaraas of, e. g., %en, vhere no coconut, trees wers gronrlng. Portulact?. johnii here seemed mos-t succulent mrl witin the largest flov;ers. The lan4 area of Ksea appeared to have been reduced asout nize tenfhs by a hurricane in 1901 but since had vegetationally qulte recovered so es tr, be a somewhat open --Guettarda forest. There mere on tile islmd inany ?&itenad remainsof pre-hurricane troes, prob:ibl.y hettarh. The seaward remnant hS.gh portion of Kriea (Fig. 2D) ha? a generally vigorous grorith of Lue.ttar&. &rim& arid & --phis were presen-t around -the margins but !5esscrschu&3i.& mas li-ttle in evidence. The highest portion of the island, %bat end nearest the lagoon, in addi-tion t,o Guettarda, as is often true of the islands at linroia, was lccgely populated by Pmdanus di.stir,ctus. Lel)irlium bidenntatum :'or~i;er; t!le major ground cover v:ith a --a grass (11876). Ximenia americana (RAMA) was scattered along the midline of the large island at Opakea as about six bushes, Forsyt,hia-like in their viney habit. Piis was in general a shady habitat in the freshest ground water area of the isl.hnd. It had the same position at Kopuano (Tokerau), vhere it vas identified only as a burned dead stump with nuts scatCered about on the ground.

Without analyzing it further there r!as an increase in floral variety in reference to approaching long islands near the southern end of the atoll.

To this point we have been discussing the Guettarda vegetational ares essentially of the highest part of the island. As one approaches the lagoon the land consists of finer partj.cles. On short islands the islani. surface in the Guettarda area may be entirely of gravel. Toward the 2.agaon the surfaces of I.= islands are of sand that it; finer tovrard the mid-point along the lacoon shore. In both cases there are usually traces of storm ramparts of essentially these beach materids near and, parallel to the lagoon shores. >he lagoon base of these storm ramparts is essentinlly high tide line and is identifiable by a' shift in color, slope and biota.

Perhaps in correlation with the finer pa.rticles and lorrer permea.bi!.ity, coconuts and --Guettarda grow closer to the high tide line al-ong the mid lagoon shores of the islands. Toward island ends the storm ramparts xere gravelly in nature and occupied by, essentially, the bushes. Of these ibb~$rr;chmidio, drops out first a.s the center of an island is spproached, then the Pem~hisand Surj.ann, leaving Guettarda, Cocas md grass on the sand7 ramparts in mid-shore are0.s. Sometimes vhe-re the lagoon beach ramparts were broad as at Gavarivari (Fig. 2.8), this was the only area thoroughly planted in coconuts.

Between the lagoon and seavrard storm r8.mpar.t~there is (Fig. 2) often a low area (Fig. 3), a male. In southern Kereteki (Fig. %A) often there r8.s a series of these lorn areas. Elsewhere (Fig. 2) there mas usua1l.y but one. This has been termed here "swale". In some places Me s?val.es had been in the past used as taro pits. No taro was found a-b Raroia and it is believe6 to be ex- tinct there.

At Tetou the swale proper was a nuddy area t,nj.c~,l.~be& by coconut trees. At Gagieroa and Gavarivari, Suriana and. Pemphis were cornon in these troughs between the ridges. In these swampy are& Pemnhis dominated tk.e pi.oi;ure, -Guet- -tarda being absent. Like1,:ise in these swampy areas Pemn7his and --Suriana formed care-like trees up to 16 feet tall, the trunks of which were only six or eight centimeters in diameter. At Tetou in the ma,le a very shallow vell (&OO KOitiO) had been dug (Fig. 2 C, ny") about 118 cm deep in i.zhich at, high tide there were a few inches of water. The water had a salinity of 4.1 parts per thousand salt at high tide and the surface of the water was about 20 centimeters below ground level. On the mud bottom of this sell the unicellular green alga, GLoeocystis grevillii (11901), formed a delicate coating.

Tie sea>t:ard slope up to the crest of tine island was of coarser materiel than the lagoonward margin of the swale. At Tetou this was covered by Lenturm repens of the same form as that found on the downslope to the mud flat from the lagoon. Actually this cover extended over tne beach ridge to nitinin a few meters of the lagoon. Portulaca ..iohnii of lox stature and occasional. -tufts of Erarrrostig amabilis were intermixed with the &turns.-- Many of the partially burned pieces of Cncos trash had the bl.ue-.green alga, %donema hofmannii on them. On soil swept bare here tkere were occasional developments which in i:lass appeared to be green algae (11881).

The beach ridge was bordered with an irregular zone about 3 meters nide, the ground of which was grassless, relatively loose, sand or fine gravel. The sand (11864) and fine gravel (1.1865) were soinewhat greenish when damp and grey ?ihen dry. This color was indvced by t~epresence of the blue-green algae Fntophys82.S.s crustacea, Scytoriema h0fmann5.i~ Masti~ocoleustesta,rum, _Coccochlo- ---ris st,aenj.na and &c-tonema calothrichoides. The very plane surface of the beach ridge sloping grsdually toinard the central male region a-t Tetou is very variable in shape. Ratner consis%ently it is a slope covered nith complete cover of IIe~turusrezens (11066). This form of Lepturus is soft and in loose spreaaing tufts ~!hichdo not run conspicuously. The highest density of Vernonig cinerea :.!as seen here. The tallest pl..an%swere often 0.7 nieter high.

Out on .the swale flat itself at, Tetou toward the center of the island, -Pe=* and Suriana mere essentially absent. The surface nas level and of mud. On this mud surface the general color is "blackish". The tempera.tur.e was found to be 26' C. about 3 cn beneath the surface. The surface had the sane temperature as the air. Temperatures of the nearby lagoon wa-ter were 26 to 26.5' C. Over the surface were strew ?.airge numbers of St,roml;us gj.bberu1.u~ chbracteris- tic of the lagoon. They were present here in rsther larger numbers than would have been expected just from hermi-t crab carrying. On this surface, too, there are loca.lized scatterings of small stones which are qul.te yellomish green with a mixture of the Gloeocmtis greeii'lli and fungus fiiaxents (l187L). In some in- tensely lit areas the surface of the mud cou3.d be seen to be greenish and covered by a thin coating of Hapalosiphon pumilis (11370). Cn the flatest surfaces there sere t-80 sorts of raised areas. One, rhile very lon, %as arched upward end while solid mas rather dry and aon-stony iilternaily. This brovmish surfaced material was a dense development of the same EapalosApJhg pumilis (1184). The other sort of raised surface was black and plek as to contour. Such areas were but tmo or three millimeters raised md were in texture adjudged to be nearly the same in texture as the nearby Hapalosiphon-covered mud or black and higher (3/16") and often qui-te stony. Tiis stoniness was that cf dry mud and probably the area was not stony beneath its somevihat dry surface. This matelial (11871) proved to be the Iiapalosiphon ar.d a mixture of Jinntophysa.lis ----,crusta.cea -%icrocoleus p&issiinus and iVIasti:7ocole11s testarum. There was a rock formation around the rocts of many of the coconut trees on thi.s mud. No biological materials other than the roots were seen to be associa%e

Here in this central region of Tetou tnere Gas an aggrega.t:'.on of crypto- gams growing on tie trunks of coconuts (11872, 118'73, 11868, 11885, Li.886, 11.887, 11888, 11889). Physcia soredis, 2. integrata azd htracothecium -----ochraceoflavum were the lichens. Blue-green algae such as I~ostocco:nmune, Scytonema hofmannii Plectonema calothrichoides and tile green a!.ga GloeocyBtis -- 9 ---- - grevillii were found. The moss -.-iCalymeres teGum was common on these trees as well. Outsi.de of this swale area these cryptogms were far less abundant. The iowest swampy areas had the best, deve7-opments of soil. By rneasurjng the elevation of the surface above Cne lcvel of the -.~a.ter-sa-hrated szndy soil in 1-and crab excavati.ons at Gavuri,isri i-t was estimaCed that ach swmpj areas ?!ere about 0.5 met.er akovu the u@cr Level. of the Ghyben-Herzberg v;a%er lens.

The lagoonward rampart ridges at Cava.riuari were at least co-~eredbg sand and small gravel, e. g. covered wi.th zaterials consl.stently small-er in size than those which covered and seemingly composed the seawrd ramps or ridges. Algal gromt'ns here bridged between the i;idividual particles aixi thus more of a soil was simulated. Under the 6ocoriuts in this area Le~i~uri~s, formed a meadow but for burned areas and leaf trash. Tiis situation at Tetou prevailed lasoonward to withir a very Pew meters of -the sandy lagoon beact! dge rviiere the grass dropped out cnd the l,md surface was more defhi-tely sandy. Cocor\uts thrived right to the edge of the :L&gocjn beach an windward a12 Raro shores v!k.ere ].and and beach graded together nithou.t ari erosional bank s'no%ing. 'yri contrtist ilt Tetou and Oneroa, !.rhere coconut trees cere being washed into the lagoon an erosional bank showd. Eroiii Kere.teki. (Fig. 1) throagh the vilhge area wnd northern Raro, dovwv:irid legoon shores, the coconuts ??era n*>tas coispj.cuously close to the ~:ater'sedge as they Tiere or: the xore v:indnar3 shores.

While the !.ag~on side of the 'beach ridges i.3 sandy intertida?. areas are of clem nell washed sand rather devoid of any conspicuo~svegei;ation 'the sand. of the inshore sides of tbese ridges et Oneroa is often bmd al.zae (Fig. 9R). These generalized boun?. areas are i.rtcrspersed w:~Sh loose sand aress and areas bound more or less distincti.ve in one may or another. One sich different area type is smooth surfaced and rather light grey. Tills (Fig. ?Cj was fomd to be largely a binding by fungus filamerits. It extended nit:? co~siderab'lefrequency far into the coconut area. Behind aid on top of Cr,e lagoon beech ridge much of Me bound sand over rel.ak%vely large are?,s "as b~ovminish grey and sornewhat lumpy on the surface. A lo~glist (Fig. $D) of algae was found intermixed here with the same doininant Syn~molocakeinerl, as domina-ted. the genera.!.ly bound "R" areas. . . On the slope (Fig. 9~)from the lagoon beach ridge into the sr7sl.e most of the gravels and rocks become very black after a rain. "1lhey are more strongly grey v~he2dry and most darkly colored nezr the sand. line with what inay be a mica1 islmd %wge gravel" association of algae. The unbound sand (Eg. gA) of .%he!.agoon beach ridge crest aress assumes a greenish cast from the activi.ti.es cf ?:he largest va.riety of algae foun3 ciosely interxixed on the atoll. Occasionally abou-t the village of Oneroa and on the ri6.ges (Fig. 96) soine siones mere grtcn even when dry. These were found to be coated with !~lastir:ocoleustestar~~m and. :jhtophvsal.i.s crustacea.

D. Lasoon shores below high tid.e line

In general the upwind atoll lagoon. shores, such as those of Gake and Kere- teki, were of sand (GAWZ) or fine sediments. As one approached the village area through Tokrerau and. Raro more and more gravel was to be found on lagoon shores and the particle sizes and high tide storm ramparts were larger. . . A major exception. to this 'ulz was the lagooil Snore of the longer leeyard islands. Toward the midpoi2t of such shores the intertidal region, as:'ivell as the supratidal region akove. it, became a 'sand or sedi!i:ent beach. Nerita 'and the ghost crabs ment,ioned. asove vere .tLe rr;ajor bi01.6~icalforms 02 these beaches as well. Stones !.opt or1 the intertidal shore kt Tetou were coated with Smoloca &3dnoides (11863). The s!i;all gravels or stones to be found at low tide line, at high tide line and just a'o~ve~hlghtide lke (Fig. 9J, K and L respectlve1y)'were similarly grey green at Oneroa. '~Bscavseof tiie constant sub- mersion of the lor:. tide stones, the intern;ittent regular silbrnersion of the high tide stones and. rare wetting ?;y rain 01. spray oi' the 'abor-e-iiigli-tide stones we were surprised to find in general the saqe aigae predominating on them...... In a few places beach rock was observe2. Bioticelly t11j.s interesting for it, with tbe,town wharf, provided about the on?.y stable areas on which in- terLida1 zonation could be studied. Tkis topic is expanded below in section V...... The lagoon beakh at Gav.i$ivzr~\?as for the most; part typlcal of sgrading lagoon beaches on the .windwa;.d . side of the &toll. 'here v!aslots of foramini- fereLL brom sand in the qqer intertided regi.on. The beach between tide levels was large p1,ane in profile betresn extreme tide limits. Up?:ard it rounded off gently into -the lagoon ri&e. Below i.t rather abruptly changed pitch to tiie pl'ane even more gent.1~sloping lagoon shallow water flat.

At Kaea the brom sand (11897, a Calcarina?) or Gmdl pelecypod shells formed the beach. In any case there was li.tt,le in the ~ayof mhcroscopic algae on the lagoon shore other thm an occasional patch of S~le~paurvilleana near channel mouths and certain cora:Llin.es (11331+-11338) on coelenteraLe corai fragments. Here at Kaea the lagoon terrace, while of .the usual sloye, had perhaps more Acropora and less --.-Poritcs than other Gake or Kereteki lagoon beaches. There was no evidence in this region of any l.agoon reef or beach rock at all. . . Ghost crabs appeared on such sandy shores at low tide at night. These were not to be seen inth.e ,rlaytime. The len& nermi.t crabs appeared to make some regular visits to these shores. Algae were essential:Ly absent.

Subtidal, lagoon. shores can be readily diVi66d into reef regions and unconsolidated shores. The reef regions. havebeex desci5bed '2s to major variations in our description of :this area at.bomohbmo above. ?Le unconsolidated shores are almost continuous through Kereteki arid Sake as sn:almcst flat sandy area. At. Gavarivari, Tetou, Kaea and Gake the sandy flat sias occasionally interruptec? by a mill-stone-like colony of Porites. At Gavarioari on this flat there was more coral development than e;se~:he~ein Iiereteki or Gake. Howevor, there was no intimation of a coral lagoon reef on wkdmrci1~00o:lshores. In one embayment at Gavarivari there was a rather broken uy exampie of an algal. reef pavement like Yie "B'! zone on the lagom shore of tine Ronohomo trmsect. Tnis (11916) was seoming'ly the same a!.ga as collected at Oneroa (on -A? flat south of village) forming z flat pavement or growhg up around Lerme*,us (11915 = JPEM 2219) tubes in such a way as to stimula-te a brancheil -.-Porolithon in form. A number of species of shells were collected (~1915). Gyp~-aeamoileta- was found both on the sea reef and on the l~goonreefs in this same "B"-zone association with a Porolithon species. It was not found at Onerca, however, in ... , essentially similar :plqq$s, but may . have. been ov&ldoked. At Gavarivzri two Isonomon species ar8 fdund, -th&'blackone'from i.nter>idal regions on beach rock and the white one from henesth 'rocks 'below low ..tide'Tekel... . Very smal.1 shells of -Arca turned up in the same~collec'tions,and a fragkent o.? the shell of cog ulicarius was fo&d fi.lled with cenienked lagoon rock material. Xhinocla.~~ :inensis was found dive below !.,6n'tidk ?&e but'near shore. Shells of the ci-am Asanhis were common but perhap's had come f?xim nearby channels. -- , ,...... At the most lag~'~n~;ardedge df tnis shallow iva.ter flat the pitch of the fine sand (silt, sedimen<,'etc;)' changes rat~era!x+ptly to a steoper arig1.e. This is tine innermost 'hfe draPin on the maps repro&ced in this rep&. The depth here is often negr 6 ,fathorns, On c\ownwind lagoon shnres ?;!here c reef is present, this same line represents t& lagoon' edge'of the reef. It is at about the lowest lagoon wager level...... ~,.. ~ .t .. . Mullet, of tv;o species,, school-ed in the channel. bet..reen the sandy Lagoon shore and the shore 'reef (KAOA.) at heron.. .'Conkon in this micso--?.agoon area were various of the coronet fish species (FG-tula-cia sp. j that v:ou!.d ?rift slowly near to investigate any operation' 'and flopped around most confusedly upon realizing the situa-tion. Tne convict surgeon fjsii, &cajlhu_r= triost,e@as, with vertical black stripes was a common visitor in the area.

Attention is called to the reefs paral!.eling the lagoon shores at. Oneroa (Fig. 2E =d map). These had the Siology, apparently, ofshdrebound and other

reef patches. ' The inner was essentially similar in morphology to that illustrated in Figre 3. And like lagoon reefs in general -tel:med ?&AX. The offshore reef was more or less connected to the shore at its (nor:hern) end only and thus xias a, KAOA.

''The PmAE dlffered little from other lagoon reefs in the fish to be foudd wd, indeed, there seemed to be liAtLe in the may of a specific fish fauna at all. Acanthurus trioste&s was common here an6 as a new e!.ement found in our .progress , .. lagoonward the very common very dark brown ~omocentrus!&r2ca. peered back at the onlooker frommany of the crevices between .the corals. No information was obtained on populations of the deep area be-bv:een the ~nd . . PAPAE the KAOA.

The barrier reef, or KAOA offshore, had little in the w&y:of afish fauna on its top. T%o different labrids, hov;ever, were considered typical.. The outer edge of the KAOA had a myriad of several species of ~arrotfl.shes feeding on or mong corals and the algae there. It was in general rnorpholcgy'and popu-- Lation like a lagoon reef patch. IV. REEF PATCH3

iJnder thi.s heeding 'he shore bound satches, or i.ag?on reefs, .anu thelaguon reef r~atchesisolated from the sho-e .::ere conside~ed. Other term,for these latterare patch reefs, cola1 hebds and coral patdies. The reef &tches of both subcategories were essentialiy of the iiiorpholoy;= of %be shore hound !.agoon reef in the Homohvmo transect area. The actual dis2ance proporkions varied, ex- cepi that in general. the acbive coral edges or reef mapins were unii'orni.

Two exte1:sive areas of shorebound reef patch we:re stu.lie3 o;~tsidethe Ro~nohomo area. These were the reefs st Oneroa and tiiose betreen tom ~:haharf and the 02.6 small boat harbor adwharf at Gerumaoz.. Tne former reef areas were so similar -to the Homohomo t-ansect, area and the lagoon .reef patches that they vill not be di.scussed here in detail.. Some of tk.e fea.:ures cf the Garu- maoa village area reefs skou:.d, hovever, be pointe6 out. YVni?.e the ilvlng coral edge is about the same horizontalwidth es on the Ilomohomo trmsxt the drop-off 1.agoonv:ard to t,he sand below is in the ne5ghboi'hood of 20 feet. Phssing inshore from the outer edge there is little in tile w8.y of 2. dead coral zorie (Fig. 3, D and E) and instead there is a pavement. Tnis pavement seemc to be ofrounded pieces and grooved soiid areas; as ti~ougherode6 ?>y moving sand. This might have been a development of such an algal. p~veixentas "MI' i.6) in the "B" zone on the Homohomo transect snd a% Gavariveri. It has ptches of algae having the same appearance as 11.831 from Tetou. This eroded yavement area 5.s in general. seven meters or mo-e wide. It has cavities so arranged that orie susi;ects loo::e chunks or cord growths have been overpovm by the pavemerit-riaking organisms. Inshore of the pavement area is a sh,nllow sand. flat which is quite extensive a~ci,at least in the places seen, at a lower elevation than the pavement itself. Ynis sand fl-at appears to slope up toward 'thg low tide :iavel on the shore and then slo;)e sore steeyly through the i~tertidalregion to hi.gh tide Line. TTnite tipped slender but dark colored sharks about five to seven feet long persisted in cruising around so that diligent exploration of the dropoff over the edge of the living coral area seenied unat-tractive. Sharks and fishes, part,icularly trumpet fishes (Fistularia sp.) were more abundan-t at Tetou aid. otker Re~eteki stations than else~~hereperhaps in relation to fishing intensi..ky. . . One case of fish mork was :seen on a Porites colmy (but oii less ac.k.ve parts?) growing on the pavement in tine "DM or "3" zone. Other Porj.tes colonies were unaffected; though man? were looked at in tnis ~~~~~~~~~on. The latsral surfaces of stoces, eqjecial.1~where they lay close toge'ther, as well as holes, >vere often outlined by a Gelidiuin (11988). %eye -%is species was ex~osedto t'ne 1.S.giit it mas mostly cjuj.'te yel3.o~. It :?as in color a. pale yellou green to green a?d browner rzhers less exposeu to 1igh.t. Under the edges of the same stones ::ha!> appearel tc ba .chis sane $_IA$&n via$ dark red, but far under the siones where -the frond:: were longest the ~~z~ig~appeared brown.

On the surface below int,ertidal levels little 1.iving mas visible. Most of the algae to be found vere groviing under but nesr the edges of stones. Some stones there were ringed vjtn Gel.id

Zonaria (11984). . . . . Shells (11982) and bones of a turt1.e p1astron (3.1983) on tne bot.tom near shore nere conspicilously green with an algal coating as yet unideritj.fj.ed.

Morrison put out about.30 large shel-1s of ----Lambis ---t~uncata to clesn on July 31. He put them in a subtidal pen-like aren, the unfinished end of the tow wharf. They were taken up =id brushed off md packed on August 27. kt .this time the algae viere scraped off end preserved (11993, 1x994, 13.995). JgJ, -Cladophoropsis, Gelidium, Ectocarpus, Sphacelaria,--- and otbr geneya were recog- ni.zed. There were crustose coralline pink crusts up to 2 mm in diameter. There were several mimai corals on the Lam%is shells. ?.he largest of -Gkese was about 0.5 cm tall and 2 or 3 cm in diameter. Vihile this coral nas rather whitish it seemed to htave a slimy coaijng over the surface end wF; thus judged. to be alive and to have grom during ti-:- one mth i~mersj.on. 'A further skudy of this material 7:ill give us better ifleas of yrovth rates on the lagoon reefs.

The l-agoon reef patckes that are free from the chox vere a:nong the most interesting biological. featul'es of the atolls seal. The Tuamotum ter.ns applicable to these are given by Uanielssori (Atoll. iiesemch 8u1letin No. 32).

At Raroia it was apparent fro%the a.ir that as one sp:?roacheci tiie more upwind parts of the legoon the reef patches were smaller md perhaps less closely placed. This seemed to be true of the a-bolls cf ?jake!~ioand Tahmea as vfell. In the lagoons of both Raroia and LIakemo the reef patches fhrrt,he dofinmind were often more elongate or tear-drop shaped.

The lagoons in the Tuamotus which were more open tq iAe sea appeared to have more reef patches in them. Such closed rings as Hiti or nesr3.y closed rings such as Tuanalce, Tepoto arid yaenga, zpp9areti to have no reef patches. Nearly closed atolls having no good boet pass,such as the pear.1 shell ,=toils, Hikueru and Taicume had far fewer coral pstches than Raroia, which is relatively open. Other correlations betmeen "openness" and t'cl.isedness" of tk.e atol.1. ring became apparent to the team as time wore on.

Not only are the copra schooners aSie to bring in their b:.essincs md curses through the shippasses, 'out the sharks come in through them, .too. In working at Raroia, the team members who spent any amount of time in the water mere run out many tines by sha.rks. These were nearly all. surface sharks, only two miGw~tersharks being caught d.uring the sumrriar. 'These were a seven-foot rhite shark feeding fn a most unlikely place aind-. manner in about tno feet of cjater along the lagoo;? shore on a sand bottom. It vias miles from the pass 'chrough which it had probably come in. The other r&$::ater shark was a four-foot blue shirrk caught in the ?ass. The aJ.gol.ogistst cmoe man, Vaaa a Timaeva, earned the undyjllg gratitude of two workers by heaving his none-foot fish spear some tvienty-five or thirty feet into a bothersome sou2 fin shzrk, some speci.es of Galeorha. .Probably the most exciting' shark stor2 is to be told b.f the ichthyologist, who .avoided one possiEiy only curi-ous elasmo5rmcn to be a very sessile crust in.a surge channel coacav:j.ty whiie the by, . . . . shark droo!.ed by, mouth open. The ic$th;rolq$.st did not report the kind of shark heyorid insisting that it. was one of tilose with t+h. 3ne rarely went more than a few minutes ;a the v+t& at. Rnroia ri-tho~1.tbsh;; investi:;ated by a shark. On3 manbar of .the teai ;mrker: a-t me, a nlo:ce cl.oscd at,oll. just nor-bh or Iiaroja, for over a ;?eek arid i';s$.?li.tid!.y SWJ no sharlcs, As a result while there is a lot of valuablo pi?srl. s!lel!. in mmy of the open ritdis such as Hsroia, only the essenticly c:Losed atolls such as Hikusru x.3 Takurne are also sufL'icient1.y fyee of sharks to :n&s pewl shell fishLng wein wor'tiiwhi.3.e. These shells are characteristic of the si6es 3f reef pstcher.

Coelenterate cc& Pociilopora end kcrooora and genera of simiiar appear- , ---.-- -- ante, cicrninate %he edges cf the reef patches.'i'his edge comes just about to the lorn ti.& level of the Iaijoorl. OYten -the edge appeared a b3.t b~ttertevel- ope6 or. the rrinfiv~ara side. ?his led to a week of vigorocs c'.iscus::ior- during the summer relative to the origin of the elongated shape of -the rn0i.e ?!opnlw~id$or31 patches. Durj.ng ti.adewind. periods tine wter is cRi;nel-- oc~ the vij.nCmard, or upwind, si?e of tne :Lagoon. Couic' i$ be tkat this is corxwlated wich the shape differences? Perhaps the nolma: higher effec.t%ve'tide Lev21 in cl.ov:nwi.nd regions and larger waves, indvoe the deve.?opent of the reef patches to grea-ker elevations.' il'moxna!. ccJ.ms woul~~iAen eq-~al%ze he cffec-Live tice Levcl Gver all the lagoon, ;es~-ing the domlwiac! coral. patches n,orci expoced to aii. at lox tide. Thus one could expect n:ore death or, dowlininr? coral. patches, espe?ialiy on their lee sides prnere wave action uould be leazt effectlue. iXot only wuld me expect these lee sides to tire& uow ROSS, bi>L Lhe stxongly cdcareous dr)tri.ti]s from the upcinrl sides could be expectel to be csrriei! omr trle lee sides es r? s~f- focating l;lanket. The mater5.a;. from both edges ~imlr?be 'deposited ir, the lee of the reef patch ?ormi?g a mbstfetum on inore corals could grow in that direction. The elongated patches i'!ould result. .Fumerous tes'ts:oi' th5.s hflo- thesis were suggested. one was to view the coiitcilrs of the patch reefs to see i.f there nas a ~rer'omkanceof ac~urcuia+,et!det~ital ma.teria1. on tb.e dovxwind side. Another was to note the nat~ireof the patch reef surface for evisence of Such greater breakdown an?. kterai grcwth of this leeward %in. In nost cases only the most contrary conclusions coulrl be drawl from ';he observzt;tions.

Reef patches in the lagoon were sem to he of ail sizes snc? forms. 'The general forms are outlined in Figures I &. II of Danielsson's re,port on Topographic terms (I~to1.lResearch Bullc-Lin No. 32). The si~allestitWIIK3 might be said to consist of one coral, csuali;: a coelenterate, growing on a bit of ebeli or a tree limb or other solid ~articieon the bottom such as an old shoe or bottle. In some insihnces it app3ared that the coral had grow io such a size that the base had been upset, $he coi-a1 head top:~i.edover; the lateral surface then corn- ing to serve as the substratum where severa!. forms h2d deve:io:~ed. Iridicntions that this' toppling process mas repeated several vimes wre seen -rariously, aqd KATUKU were seen from a foot or so in ddiameter toth"se as lairga 8s a barn. If these develop suff5.cieritl.y near the surface SO %hat tk4y can be seen, tkey are called MABAIII Those coral patches at the surfacede;;enr?ing upon size are called TIME, if smail, PUTW, if medium in size, &ithK%:W?UB &in(! the nm.e for the largest, often as much cs 100 meters across or ove?.

The smaller categories of coral patches are very i-rrr-gular iriounds. The large coral patches mere in generd in deeper water mid in overal:. aspect truncated conies. Howe~wr, in more intimate detail the upper trren-Ly feet was aptto he quite vertical and the upper three or five feet an irreglar, over- hsllging shelf. The veiitical wal.1~mere 1.ikely to be dcisely covered with various species of Cai~ierua. SmSU1dYledges below ken feat dovrn co1i1.d be eqected to be covered witin Halimeda. Tie sloping bases were to a. lrirge extent covered by fine white sedinent, dotted wi-th irregular chunks of coral nateriui such as might have broken off the rim of the reef patch. Gn these chunks coeleilterate corals and Caulerpa were abundant. . .

The snrfaces of many of the reef patches reached low vater level.. There mere no terrestriaZ forms on any of them though a Irery fey !ad chinks of dead coral so p1-aced that they protruded from the water even at high tide. Such appeared -to be blackened by 'the same blue-green algae a.s cause the bleckening of spray zone rocks alcnc the sea reef shores.

The reef patches that approached the surface were 3.at on top. The smallest (TIRARE) were more or less alive completely across their tops. If one visits a successj.on of incree.sj.ngly large reef patches one fj.ncis 'ihar, tiley are progressively like micro-sto3.l~ in that the center is mare apt to be. a pcol a few feet deen and the edgk a rim a f&vi feet wide inore or less co:nplete and higher, just behv? low tide line. Cord patches of intermediate sizes (PUTEU) were apt to have several snaller sand-bo.korned pools in place of the one large . . pool area of hig re~fpatches (KARaA).

Large reef patches had 'a rather consistent ,externa:!. arlatomy. They rere very much like the lagoonward elges of &e lagoon reefs. The rwryin of the rim -#!as usually irregularly rounded and almost entirel? of animal corals; corres- ponding to the "Gn zale sf a lagoon reef. Horizontally this area was regular in form, usual.ly less than one meter nide. Inscirdiy it could. be expected. to yield to a uniform flat region. Here the 0i.U Cora~'animal, Funria, could be taken as an indicator organism. The branches of c,oelentera.t,e cora.ls, wnich at the edge of the patch top were sepirate, dendriticdly branched forms, were here (on "E" or "F" zone) a nearly sol5.d mass of banches with but small. cracks between. VGhen near the surface Uiese mall cracks mere filled ciith (or the branch surfaces encrusted with) a prostrate Zonaria and other similar algae.

Algae were not conspicuous on reef patch tops at Raroio, except locally near the rim edges where sometimes prominent areas of ?oS.ysi~honia(11015), -Lophosiphonia (11016 and 1101Li.), and Bryopsis (1.1011) were to be tound. These popularlts were particularly ~bundanton windward edges. The windward rim edges were somekimee more loose in structure, often havkg holes through t&em, and often more overhanging than the lee rim edges.

The micro-lagoons, or pool areas in the reef patch top,?, -em as a ru3.e s sand or sediment flocred and a foot -to a meter Ceep (ss in the lasoon reef "Ct' zones). Scattered about couzd be expected dead. coral animal fregments, often with living coral growths similar to the smallest reef ;iatches (RAPWC) described above. The inner edges of the rim (essentially equivalent to lagoon reef I'D" zones) were full of small caverns, nasty looking eels and a host of other fishes. Algae such as Rhipilia choke many of the smaller holes mong the dead animal coral branches, and through binding of sand grains tend to fill. these holes in such a manner that a rether solid mass results. At Raroia from the air tt oftm appeared that the reef 3atches '%:ere in lines as tY.ough separated f'rm sach othez. by circulet-ion cells rad'?.ally 2.r- ranged jn reference to the downvi!nd slioras. Oil the map these show corie~icu- ousl;y on the most southviesf lagoon ,chore near Oneroa. Piat their direction is radial or in reference to the prevailing winds is seen by the arrangement of the most southeasterly reef pt,~iies shom. Unfortuna-tely, ve 3S.d not have sufficient fli.ght tjme available to take photographs of the lagoon iteelf and thus this pias not, followed t5rough.

Piscatorinlly the reef patches were !.ike the shore boun6 ~eefpatch faces but neither so rich in species nor in numbers. The squirrel fi.sh ax rather comon to the patch reefs ad are the notable new ele!:;ent in the ~'i&fauna as one passes from the snore out into the lagoon.

Phycological1.y tho vertical faces ol^ the reef patches riere uniqve for na- roia. They mere often c~veredby great quantities of a hrge-jointed. . Halinzda and by masses of re3.6-tively sjm:>le forms of cauLe_rx&c&&;,ngul. Masses of Caulerpa b5.kinensis were favorecl pastures for turtles. Pendent from overhanging coral shelves one .found. ?]pun occasion six to ten fee-$'Corn Pse.i~dot&&gspo~ -untillarum--- home. This in ths field looked. not unlike a thlck gelatinous sheet of -Ulva irregularly four to ten centiine'tsrs acsoss.

Aspects of vertical distrib~;ti&wre pursued both on the laild above and into the water of the reef edges in the lagoon snd on the sea shore belo:? %he intertirhl region. In respest lo the intertidal regions ae viere pariicul.ar1.y anxious to see whether or no-t t:ier& was a correlation bsixeen tides and. t'ne observed distribution of Living things. .. . , The intertidal region is a comnion' point of departure for ei.evationiz1 stu- di.es and. .thus the tides received consf~cerationfirst. 1.i: -nas qui';e apparent that determining rise md fall of .the tides be70n.d the sea reef xoxld be quite a f(3a.t ?Ath the materials at had, thus a tide stick was set up on the vkarf in the lagoon. ?t kzs very quickly determined that. ivhile the 3me fac-tors were not so muchiy affectes %he vertical components of %ke tide cvrve %?ere very much affected by the wind anfi sea roughness. Thls vas presumably a result of the water piling 5n over the reef and niling up against the izgoon shore more with some winds than others, the ou-tle* t'nrougk the gass rcmaj:ning the same. It wss determined that 3eme= tjde rmge iii tine lagoon nbs probably a little over one foot. Our inpress!.on, and it ':as only :'li .impression, was t,hha.t the tidal vari.ation of the sea ou-tside the atoll wc.s betvreen t.m and three fee.^ or about double that j:~ the Lagooa. Tides ere reckoned from ),.?La., about a tnousand mi?.es awcy across certeilr? factorial nodes. Tr~erewa.s at least as much as fifteen cen-timeters Zifferencc j.h siccessi.va high t.ide levels, and similar differences be-tween successive low tide levels during our seriod. of observation. The three basic ones observed (Figs. '7 tiiid 3) can be called from conven- tion, supralittore:, littoral and si?bliYioral. Upon occasion divisions of these or variations from this pattern were observed, but the observations were few, rather closely placed geographically and no accurate leceiing mems were available, and thus little can be said justifiably as to 7~ha.tthese anomalocs situations mi.ght signify.. . .

Below :the lowest 1.evels expcsed by the tides &t the reef margin the biota was dominated by a smooth coating of Porolithon onkodes. This extended dom- wards atleast eight meters (no one measured Elis) and covered over 9: per cent of the surface. On flatter tops of spurs an occasioeal area was ccnspicuo?:sly &. dotted Grith PociVopora. This whole region domina"ced by ---.- Porolithon can be considered an upper sublittoral zone.

A coral aninal zone below' this level was report2d 'by the geol.ogical..members of the party. Such a zone wo'tld be a lower littoral zone,, arid ccrrespond to v!hat has been observed elsewhere by others and i.n gerier&l. referred to as a ten to twenty meter terrace cover-sd with a forest of coelenterate corals,

Vertical distribution along the sea shore near ~aruroaoa(Fig. 5) was noted sufficiently that the sequential evenCs are rather certain. Sowever, there are special problems involved in study4ng the vertical aspects of distribution on acoral reef. Firstly the'sea breaks over the very irregular edge of the reef almost constmtly. At low tj:des on calm days the reef pool is l.ikew:.se calm with no waves. As soon as the tide is hi.gh enough that the vjaves are not completely broken at the sea reef edge they run across the reef fia-t and there is considerable wave action along the landward edge of the reef. Mowhere on the reef margin does there appear to be a re~vlarsine relationship between effec- tive water height wd time.

In Figure 7 we have presented a summary of observa.tions on the Iio?nohomo transect sea shore and reef. To take account of the tide 3001 like nature of the reef and tne desirability of different vertical scales the figure has been broken in the middle by en l'unscaledl' portion. For that portion of Figure 7 concerning the algal ridge and t,he spurs grooves this unscaled portion in- cludes the positive and negative changes in elevation met in pussing up over and back dom beyond any algal ridge (Pig. 3) or cuesta. . that :ray be. present and. the elevational changes within -the pool, itself. . .

The algal ridge and the organi.sms living &I and in itcan stand. ernersion but also are found dwelling constantly immersed. Tne algal ridge. is thus considered to be a sublittoral fringe. As examples, the urJper sublittora?. fishes may feed here on the algal and other materials of the intertida.1 area but they are always immersed in the wa.ter. They, themselves, are not consi.dere3 to belong properly to the sublittoral fringe.

Porolithon onkodes is a fine example of a tygic~lPringe zone organi.sm for it lives better here in this subione under the unique circumstances of surf, aeration and brlght light tharn elsewhere, though it is wide3.y spread in its major zone, the sublittoral zone. 1% occurs below low pool level on the reef flat, in the channels, on the lagoon shore and beyond the algal. ridge as a coating of the grooves and spurs dovn to a depth of at least four to eight meters. The &niroa-- zone is regularly exposed by th-. low tides but briefly. It has, Lhrefore, beer~ tretit.ed here as manifest of a lore? littoral fringe or more simply a lower li-ttol-a1 zone. The species oi-' && found .$.ere in always- suherged localities. Ele &- spccies forming t?Ls turf ~t Rar3i.a laid Takume seems to be an ele~ationalcor-elative to such jointed coralline axial species eisewh.ere as Cora!.li".a ~C~ilis. --. ----. .. . At theshore edge of the reef pool. the fauna is not tie s:me on the upper end loner pal-ts of thn bro~mintertida?: area. For the present me accept the lev+ er area occupied by Morora &ranulata as being eqcivalent to a sublittoral fricge. Thais hiq>ocastmeum occupies the upper pa,rt of this shre area. The sea. reef areas typified by the cccupancy, of This andk3phiroa have been (~'j.$.7) COR- sidered as the lover littoral areas or1 the 3ea shore. It my very weli be Yn3.t this region should be treated as but a singie 'bio~iorniczona!. unit. There is not the &ear br-ealc bdtvwen them one usually finds betwec?n sublittoral and iit- t0rdL zones and it vrou1.d perhaps be better to treat this whole region as sublittoral.. fringe.

Higher .in the intertidal area on the shora Neritn pli~ataranges essentia!.ly over the loner edge of the black zone doninate$. by @~'torihWal.i.~nrus- --tacea. Tectarius is higher on the black zone. Recpe'ctively these tao have been taken (Fig. 7) .as indicators of mid- and upper littoral zones. Mew& coccinea, on the grey rocks, was th.ougkt. to be an indicator of s su:&iittoral fringe (Fig. 7).

Above the intert.iual zone',Lhe atoll was covsred ~itha rather ubiquitous coating of blue-.grsen algae. ' Thcze bound the sand or formed a grey to blackish coating on grave1.s and roclcs, &d even on baTk md dead vfood. The macroscopic vegetati.on was at its margin a Lzls!! zone. This hadbeen dsscribed in our descri-ption a.bove of %he sea beach (Seciioe B) ,+cl the l.agoon shore above high tide line (Section D) . . . . . The bush zone pas a wedge~shapedencirclingmne, perhaps two meters high on the sea shores and one ha3.f to one meter high on the lagoon shores. On lagoon shores this zone was sometimes absent along -5he central, portions of long islands. It occurred to us that the bush zone and sea boach might represent the horizontal extent of variation i~t!e position of tine Gh-y'ben-Iieraberg fresh water lens margin. This frzsh water lens has been found on other a-tolls to approach or extend under high, tide line on the layoon shore. We presumed this to be true on some prts of Raroia, e. g. at Oneroa, for in such places the coconi~tsand Guiettasda are fomd right at high tide line. In such places a supralittoral frihge is absent as well as the bush zone or lower ~upr~littoral zone.

One must note

At Takume it was noted that i32pnia grmdis was restricteL to tiie highest parts of the island,. tb.e ridges be%ween the very large taro pi%:, ?xi mas ';bus at elevations of plus i5 or 20 feet. On Faroia thelsliulds u?on which Pisonia mas growing were proba.bly no-1; :is high. Sinll.ar1.y &xP>& sulilcorrlal~?:us found on the higher parts of islands, but the elevztion of none vr8.s nea::ured viith the hand level.

The incomplete channels an?. lagoon she-es presented bu't fev~opportuni:Li.es for vertical distribution studies. Umcor~soiidateLZshres p?edominated and, e. g. a.t Rlata,ira, -rerebrow intertidally. (probably Lhtophp~~s,~, cmstacea! but little grevi. in such places that could be relate2 tovertical dis-t:aco. village nrharves and occasional conglomerate rock' areas m~dea few se-is of' observations possible. ... .

At Ga.rumaoa (Fig. 84) the lagoon beach had sevecal rock out1i.er.s yhich r:hile not continuoas gava, >:hen talcen as a whole, a fa.irl.9 cont,inuou.i ~.c.tilre of .Lhe veptical distribution to be found on such a sandy'shore. The highest marine algae were founc! in a smdl tidepool on the surface of a rock area on the shore. The sand in the bottom of this fifteen centimeter decp srflali pool mas bound by algal filartexts (11339). This 'pool ms above the uppermost 1j.rti.t~ of rnacroscopr'.c dgnl growth. About 15 cm below its edges a grsen al~acovored the rocks fdloned lover by other organisnis at other levels. Figure 6Billus- trates the zonat5.011 on one of the few rakher large isolated bul.ders found in the sans along the lagoon shore.

The vertical zonation found aiong the &?ores of En incorip!.ete chamel at Cake is illustrated in Figure 8G. As the black grc.vel (Il4:lj extenc?s elorig the shore of the channel lagooliward it gradually becomes smaller in diameter and less conspicuouslg gravel, e. z. the gravel graded ?ntosand. At tie ia- goon end of the channel the shore 7ra.s of sand ;ad a black zone mss no longer to be distinguished. The coarser sand of the :.agoon shores (1Ui;O) seemed predominantly fragments of !::hat xay be Porolitnon pard~eriof the sea reef.

The Garumaoa. villege i7iia.rf provided tile best opportunity for studying intertidal vertical distribution in the lagoon. Distrfbution was gbeerved to be somewtnat different on the two major sides of the wharf. Ll;io:ri.se'there were some differences laterally along the wall the significance of vhich ,were not clear. Figwe 8D illustrates such vertical distributional. c2fferences by the slopes of the lines.

In Figure 8 a five-zone arrangement of the biota can be inferred as a general rule. pbhere solid materials extend sufficiently high, a supralittoral zone can be said to be represented. The littoral zone be1o.v: this j.s essentia1l.y divisible in turn into upper and 1or;e;. zones; .bhough in one case (Fig. 8F) v:here the size and position of tine rocks preventecl a real analysis, tLree 1.ittoral zones may have bee3 evid~~ceci;or ike -hSuliacel aria may repre~ent,rn:>r-e tr12l.y a sublittoral fringe. A little consideration cf the exposure of the habitats in reference to waves and wi.nd leads us to suspect that tine vari.aSle elevations of the breaks ill.ustrated between the zones are due to ?rave actinn.

Two lower zones (Pig. 8) nerein some places evident,. Tnese rere considered to be a sublit~oral.fri~~~e:andan upper suhli.l:toral. reeion. ';ii.ie the biotic elements of these were present, they were in pl-aces not nell :?orE;ed in- tosepara-te zones. On the shores ofthe incom?lete channels, onljr one zone, an upper sublittoral. zone, could be found.

The coelenterate cor;,lls were active in ia%oon- areas in fchat is accer,ted here as the upper sublittoral zone. Beginling a very f'ev meters below -the surface Caulerpa bikiiiensis, C. .piclseriyii, E&Lmeda 2~~and. Pse&g:s:tr.aao." antil.larun1 became evident. These covered the sides of lagc~onreef' patches essentially to their bottoms. It Gas felt thzt these :soecies !-ere i-ndicators of a mid- or lower sublittoral zone. Belovr a.bcut six nietess, there appeareci to be an increased aburidarice of individuals of Spondylus '+id-cna etc. ??&her 9 ";."-2 this was a natural distributional phenomenon br due to fishing is questionable.

The areas between the islz~dsdottir,g the re-f are channels. These are seen in the illlistcation (Fig. 5) -to be of tvo kinds. The three j.slands on the right are separated. com;3ietal.y by one kind, compLete channels. These are vratermys connect-ing the sea with tke lagoon. Towerd the center of the figure three of the ot'ner kin$, hcom2le.te channels-, show. They. are mter fili.ed at their 1a.goonward ends but do no5 separate the above-tide land i~tosepamte islands and connect to the sea. ?eef f1a.t. Incomplete c3annels are related to the various pond types found on the atoli and described hsre belcm.

The bottoms of complete channels are essentiaily plane surfaces but often have protruding islands of ccnglornera& materid in thein. In generci:L a% low tide the ckannels are but ueri;aps thirty centimeter3 deep at the sea. end, but deepern gratiually toward the Lagoon until at the lagoor', end of the sol.id bottom t'ney my be two feet deep at lov: tide level. Tne Raroiens refer to t'ne reef flat as AKAU and to them t'ne MAU continues between the islands insofar as the bottom is solid and nas the general character and population of reef flat regions. Lagoonwrd of the solid bottom the channels deepen to a few meters and. are in charhcter, then, like the shdlovr lagoon bottoms. In dom- mind areas the mouths of such channels are often closed at their 2.agooiirvard ends by a bar of gravel, sometimes apparen-tlycapped vith coral. rock. ' The gravel bars as shoum in Figure 5 interrupt the shcre bound reef patches, or la-- goon reef. In. whdward areas .the lagoon mouths ha.ve szn~ysimilar bars and there is no shore bound patch reef to interrupt. .P.articularl:? near the edges of the som?l&i;e channels there are often numbers of 'rather flat rocks unCer whish,ther~is almost &lv?sysa population of grey spotted nioray eels (mlot'n~rity &'&). These eels, c!:mmon to %he reef pools, were at most clearlytimi?., cstere the black--6iw;jed sherk-; (g.?Zk:~m&) common to the same chan~alsand p.0111 aiees. The sa:'e gog

In the deeper of Yne complete channels tiiere is a i2ezte.r representetion of corals and such other elel;ien,~.sas Diadema aild Eor.ii&uh:gg aequlir?c~tia&gar.d a gr€ater profusion of species. The -.-.-VenPe-tus and --Iirupa - spscies %ypj.ca!. o' the reef pool areas occasionally appear in the channels. In tno chanijels noay . . Gavuri-vari toward the lagoon fragmennts of coral. viere ::ourid .with some sulfn,ges actually covered with ~,ermeti.ds, Some channel areas ju4t !?orfih of Tetgu. were entirely blackened ~:ithwl-1a.t was probiibly ."i,:'is sane -j-er:iiet,id on their bo.ttoais at the sen en&. Yne same or a similar slaari Cermetid grel;+ in an 5.nteres-Ling relationship with the coral.l:.ine alga forming a shore hound. pavement'kke that in the "B" zone of the lagw~ntransect at iion;;3homo.

Around the bulders on the bottoms of more centrul resj.ols of the channels near Ga.rumaoa (Fig. 5, e. g. behem the three i.s;ands on the right) tne~e?:ere often Caulerpu urvilleana coloaies (and e. g; at Lagoon end of the chann.el at Kaea, 11890). Nearer shore v&at was apparenCLy the same i.!Ii.crodictyon ck~,ur~$ was the most conspicuous alga and'under the edges of iiock.s below low pool level but very near snore v~ha.t 8.ppears to be Dictyosuhae~i?.cavemosa was the most abundant macroscopic alga. The more or less vertical intc-tidal shores' cthbr than for being coated more thicltly with a bcovrn scum of blue-green a!.gae are like the shores of tne sea reefs.

Irlcoinplete channels appeer to be closely related biotica1ly to the- lagoon. Certain typical lagoon species cf clams and Such gas+,ropds as Cerithj.um &zg were found common1.y. Wile the holothuri.ms cormon to 1.o~tide 1.ine else- vhere vere seen again here, the yellow Porites cormon a.t th5.s level on the sea reef was absent. In fact no living coelentrate corals orwe seen in the incomplete channels though they didapgear on tine gravel bars at their mouths upon occasion.

A rather detailed study was made of: ponds and incomplete chmmels at Gake and a classification of them devised. These ,pond and incoiilplete channels associated with the lagoon shore we-re distinguishable as aseries of biologically or physically distinguishable .types. Tie most isolated of these (2921) were flat damp spots often covered by green strsr.ds of Fhormidium pau:rr'aceu!n or Anacystis montana (11423). These spots rere in the gravel between the sea beach ram?art and the heads of incomylete channels, apparerit1.y cons5.8erably above high tide level. . . One pond or damp spot (-2 2) near the lagoon shore end of the Gnke iren- sect was apparently water filled a-t exceptionally high waters (the collections had salt on them) or during rains. On the most moist bottom parts there was little other thai a ge;atlnous yeliow-.brov~m coating (1.1433). On the most soil- like drier but profecfed arsas were efts of Wo-bhrir pi.losa i.ncorgoyat,ing --Anaxstis -dimidiata -. - aad ->ktopxds,a&j.:: ~~c+~a,c~,~ (11432). Moss-like tufts and coats of Calothrix pilosa (11.43/,.)in pire stands covered most CX the r.;si~inde:. of the pond bottom. 'This pond was peT!mps one left in a gravel hook more or less mahis, acidula on the sand beach front ard betmeen it and the Lagoon.

About fifty metersinland from the centcr of the lagoon sham w~s:a pond (Tme 3) about 8 PA by 20 M long. This was a freshish water por1d. Neneil. says that sand along the lagoonward shore cf this pond indicates that it mny have originally been a low spot in the island shore cut off by shore sa!d and thus isolated from the' lagoon, %ere were several -sirnil.ar ponds seen. 'The fine silt in this pond was consolidated at tine surface into ar oTange red c&ce of such ponds.

A shallot# (1.5 em deep) pond (I&+ 4) was selected as belonging serially here. It was covered on the tottom by an orange alga!. crusL am3 around the edges by more of this colored alga': crust. Though probably not regularly re- ceiving tidal water; the same mullet was found here as in the folicwing pond type, Type 5.

The island, areas of Teuranote ad Tilragera meye separated by an incomp1ei;e channel. This channel (pond Tn~e5) was shut off from the lagoon by s sand bar on which grew a number of &his- and Niesserschmidia-- busires. The pond thus formed was brackish. It was a repository for refuse and excrement. The water was green; as though with a. chlorophycean algal bloom. 80 equipmen.t was av&iL-- able for study or ?reservation of this plankton. The bottoa, (maximum depth of 2 meters) was covered by about 1.5 cm of very soft sediment over gravel. On this sediment were occasional patches of very soft brovlnish purple Phomijdiirm myraceurn (11422). On the flat and zear water level shores were large arecs of the orange red algal coating discussed variously above. On beach rock isolatcd .as a ledge in the pond was a fine green alga. Under ?later and on the beach rock around the edge of the pond there was ar! abundance of 8of.t (Newhouse said llfluffyu) orange materisl !11/+24). Gravelly sand shores in p1.aces in the water's edge had a dark colored blue-green algal mat 'tfiat %as in pl.acf?s broken into small pieces approaching balls in form but still soa:ewhhat engular in out- line and'distinctly dorsiventral. ... , . , >. 0~;~tact.swh.ere gravel and beach rock shelved into this pond there mas a multitude of the small gastropod, Serithium breve. . In more sandy areas, similariy just below low vater level, there was aiq abundance of one small clam. One sipunculid norm, perhap peculiar to this environment, was found a few times. At night, and only then, a myriad small (2 cm) colorless shrimps. lrrere attracted to any slight distutulbance at the bottom. A small crowd of one species of fish (Muugilidaej lived in this area.

Toward the east end of this wooded series of land areas a somewhat less isolated pond (%pe 6) was discernable by the addition of Albula -, the mild fish, to the fish fauna descrlbed for .the above ponds. The same clam and gastropod (Cerithium) nereirl abundance. pie da.ytime investigations re7realed none of the shrimps observed in the Ty~e5 region. Brackish water gastropds were generally abundant. The only two Raroian records for tmo species were obtained here. One of tflese rvas a Ne~iti-r~gfoiind just beneat,h the then current we.ter l-he. The other was a very acti-ve pink cap shel.1 (not unlike the Hungar- ian cap-shell) found at siailar levels on coral fmgiiients somewkat buried in sandy mud.

It should be emphasized that none of the ponds in this s&es EL far appeared to be a pond that ever has a free exchange of sea water other thzn perhaps by storm waves that sweep over the land to them over 1evel.s well a'bove the highest tide levels. . .

Pond 1We 7 as selected was oi'small ponds near one of lbe 8. The Type 7 ponds were apparent1.y in connection with Type 8 and the Lagoon at the very highest tides through channels lying above the usual high tide levels. Though these were small relatively shallon ponds Acanth~~idtleappeared in the fauna in addition to the previously mentioned fish.

Pond Type 8 is represent,ed bjr ponded channels rey~larlyhaving u channel opening to the lagoon vith -the higher tides. Coral grorc~ti: xppearsd. meagerly here near the lagoon entrance. In addition to the previous1.y ment,ioned fish fauna there mere additionally members of the Scaridae. Rot on3.y mas the fish fauna population distinctly larger thers but the individuals, for examp3.e of ----Albula, were large. Balls of healthy Jania-.- (11490), a filamentous green (11./+92) and a small elm (11.493) ~;el-eto be i^ound. The water, though no measuremerit was possible, was seemingly nearly of the same salinity as the lagoon watey.

Incomplete channels open at a1.1 tides to the lagoon appeared to the next type, Tyue 9, distinguishable bi.ologically in the series. Here aarti.cul.arly near the 1e.goon end corals were abundant and there were some holothurians. Tl'e fish population mas broadly variable hut typified by a neon blue damsel fish (Pornocentrid) with s conspicuous yellow tail. .'

The more strictly intertidal region toward the heads of incoir,$ete channels (pond Type 9) is domlnaCed frequen-tly by the red mi of 3ntophysal& crustacs (11L35).. Along the,sides of such channels in flet areas probably covered by highest waters are crusts that seem to be transitional to rock. These are dominated by Entophysals crustacea, Svliiploca kieneri, ~a~~igoc~l~eus testarum, P'lectone~-terebrans and associeted fungus filaments (11445). Lower and approximately one-third of the way to the ntouth of such a channel the region below blackened by Entophysalis crustacea (111+31) me.y be forming beach rock . . one form. This surface is a mixture of the "red mud" described above and stones that are predominately yellow brow vith, again, Fhtonhyga3.i~crus'tncea (114L7). On 1or:er surfaces of one such stone were to be found 1 mm disc-like patches of blue-green algae (11448). Further tomard ihe mouth of the channels this zone is entirely gravel, coated yellow brow with htophysal& crustacea and Calothrix scopulorum (11.lJJ) on top and clean beneath. This forms a zone 20 cm broad vertically. At the lagoon ends of some such channels Cner is a transition to sand as in the case of the black zone; and there this yellow brown zone can be distjnguished no longe?:. The cfiannel beSon low ticie line insofar as observed was sand, corn1 or boulde? tstt,me?..

Tile lagoon shore itself may xell form a termha.!. mesi~bcr, =ee 10, in i.he local series cf aquetic habi4;ats associated with the lagoo? shore. An atddition- a1 discussion of this terminal. me7nler j.n the series is to be found undsr the dis- cussions of the lagoon shores. The shore at Geke mns covered by very find sand, has a fish population that !nos% imedirite to high tide line is chxaste~izedby the fish C'nromis cueruleus-, bla&-fhned n,u!.let and bi.ack-tinned sharks. Tvo octopods were collected at Goke in the very shaLLlocr (15 cm) wnie? as was one of two remoras seen. FIGURE I RAROIA ATOLL

GAKE

FIGURE 4 FIGURE 5

(PATCH REEF1

0u 100 200 300 400 500 METERS RAROIA ATOLL GARUMAOA TO THE LEFT AND THE SHIP PASS AT THE RIGHT. LAGOON BELOW. FIGURE 6

LAGOON BEACH RIDGE

LAGOON INTERTIDAL SHORE

"0" GRAVEL SUBTIDAL AREA

"M" CORALLINE ALGAL PAVEMENT

"N" CLOSE LYING CORALLINE NODULES

"L" LAGOON REEF POOL - LEVEL LEVEL

D 'L1' ROTTEN PocILLoPom CORALLINE 8 SILT COVERED

E "L" ALGAL COATED POCILLOPORA

F DENSE LIVING POCILLOPORA

G ACTIVE COELENTERATE CORAL 0

0 10 20 30 40 50 I I I I I I

APPROXIMATE SCALE IN METERS FIGURE 7

GUETTARDA 8 COCONUTS I - W _I 180 11 W 5 SEA REEF MARGIN LOWER SUPRALITTORAL _1 0 a0 I

RIDGE 0 TO 50 CM HIGH

MLLW =O.O

SEAREEF POOL AND I I0 -20 METER TERRACE DOMINATED SEW SHORE BY COELENTERATE CORALS FIGURE 8 LAGOON SHORES

GARUMAOA LAGOON BOULDERS IN SAND GAKE INCOMPLETE GARUMAOA WHARF BEACH AT GARUMAOA CHANNEL

(a) (b)

70~r-

UPPER S!'BLITTDRAL UPPER LOWER LOWER UPPER SUPRA- SUBLITTORAL FRINGE SUBLITTORAL LITTORAL LITTORAL LITTORAL LITTORAL (UNDIVIDED) (DIVIDED) FRINGE ONEROA PROFILES FIGURE 9 -HTL BELOW HIGH TIDE LINE

REEF FI SURGE AREA ,L,M LAGOON REEF KApA I I, / A HTL l HEDYOTIS

MORINDA 8 PORTULACA MICROSORIUM 4 .. . . . - -EUPHORBIA SUR' IA

/COCOS 8 GUETTARDA -ROOTS EXPOSED

SAND E WI' - B HTL HTL

, IUETTARDA MESSERSCHMIDIA MICR~SORIUM I HEDYOTIS 8 MORINDA MWDA 8 t PORTULACA -COCOS FALLING INTO LAGOON

TWO DENSE GUETTARDA. WNDANUS MICROSORIUM, EUPHORBIA SCAEVOLA AREAS IN CIENTRAL AREA OLD DISSECTED GRAVEL RAMPART REEF PIDFE /(OUTER) GRAVEL RAMPART BEACH RIDGE SAND BEACH C HTL w/ i APPROXIMATELY 450 METERS