/ Ptlycol. 14, 468-475 (1978)

DIATOM COMMUNI TV S TRUCTURE: TAXONOMIC AND S i A TIS TICALANAI.VSF.SOF A MI.S.SI.S.SIIMM .SALT M.ARSM'

Michael J. Sullivan

Dcpdrlniriit, I',C), l)t.iwfi Bt). MK!ii»ippi .Stale t-'iiivtTMly,

Mmiuippi .Stale, VlixsiMtppi

ABSt RACrr

Edaffhic diatotm were collected on a .seasonal ba,si.sfrombeneath pve monospecific stands of sf)rrm<itof}h\te\ onGravelme Bas .Marsh (MLs.sLssif>pi)Jiom 1-t October 1976through 21 June 1977. Of the 119 diatom taxa encoun-tered, otdy sei'en were restricted to a single edaf>hic habitat,and five of these accounted for l7.2*'/( of the individualscompn.sing the communtty tLssociated uith Distidilis spi-cata (/-.) Greene. The single most abundant diatom wasNavicula iripunctata (.Miilt.) Iiory, which accounted for21.5% of all indii'iduals countetl during the stud\. Iia\edou a 2'wa\ ASOl'A of sfiecies diversity {li') and the num-ber oJ taxa in a samf>le, eilaf)hic diatom community diver-sity was highest beneath 1). spicata and Spartina patens(Ait.) MuhL, linrest beneath .Sp. altet tiiilora Loisel. andJutKUs r(K-tiierianus Schrele, and sumrwhat intermedi-ate j or the Siirpus oltieyi dray luibitat. Structural dif-ferences belween selected community pain were quanti/iediLsing a similarity index {SIMI) and the values generatedwere exceedingly variable. A multifde regression analysisrei'ealett that structural differences amongst edafihic dia-tom communities were related to differences in elex'ation,far red light energy, ammonia nitrogen, \oil miiisture, andtentatively, height of the spermatophyte canofry.

Key index words: community .structure; diatoms; Distidi-lis: diversity statistics: Juticus; .MLvsLssiffpi; Navicula;.salt marsh; Scirpus; S{>artina

Edaphic salt rnarsh diatoms, or those forms livitigeither «m t>r in the upjx-r tiiillimeter of muddy sed-ittietits, (>ossess a cotitinuous distribution over theentire tnarsh surface. This ituhides those edaphichabitats of the tnarsh l>oth with and without aspermatophyte cover. Despite the ul)i(|tiiious tiatureoi e<laphi( diatoms iti salt marshes atid their signif-icatii rates of pritiiary prinluctivitv (2), tliete are fewstudies designed to utiderstand the relationships IK"-tween their complex cummuniiv striuiute atid en-vironmental factors. Of these, two st tidies have fx"endescriptive (9,11), otie was ex|x"rimetilal in tiattite(10), an<I all were carried out iti Atlantic coast saltmarshes. To date, there exists tio published actountol the e«laphic diatoms of atiy (ttilf coast salt marsh.The present pajH-r theteff)te destrilx-s the structur-al characteristics ol five edaphic diatom cotnmuni-tiesof a .\f ississippi salt marsh and relates differencesamongst conmitmities to an artav of eti\itotimentalfactors. The results for this (iulf ((),ist marsh will IK-compared lo those of previnus studies.

'Afcrplrd. to f une 197S.

I)K..S(:RII>'I ION OF SI UDV AKK.A

All iirlil work was rarrird i>ul in (•i,ivrliiir Bay Marsh, M I M I Vsippi (N.'lirjr^ti-. VVMHMO'.V.r). lrHalf.1 i.i. 11 km SY. of tin- (lullC'.o.iM KCMMKII UilMiraloiv ai (Kraii Spriii){< (Ki(<. I). I lie iiiamh\y iiic);iilarl\ IIIMHII-II, lackiiiK any vitilitc itipiil ot licshwaUT.Ihu* (iiavcliiir B.iv \I.ii>li i<'ptr<M'iM<i a iiraiU (losrtl s\sii'in.wilh iho iMiK wiuiir ot llixHliiig w.iin U-iiin via c-x<fplioiiall>lii^h ti<lr« ill iiraih\ MisMsNi|>pi Sound. Kivr inonoltpit ^laiuN oliiiar«h «|H-linalophMr\ wrrc (hovii lo (Icliiicatc <t|>r(ili< ril.ipliicdialoin (oininiiniiic^ and iiuliidcd: i) l)i\liihti\ ifiiailii (L.)(iii-«-ric ' I)S; ii) .Snrfrui (./iirvi i',iu\ - S<); iii) fiinru.i rufmmtinuiShri-lf = JR; iv) Spttrloia allrrmjlota I.IHM-1. » S/\; v) Sp. fxtlrM(Ail.) Muhl, - .SI'. Ihc iwo-lcncr abhrrvialion following cub<i)K-riiialoplivic il uvtl in this pa|>or lor piit|M><ic« of lucvilv antltlaiiu. I he (ivf «|MTiiial(iphylr!i jitrin u virliialU (onliniioiiN cov-er over ihr rinci({riii M'diiii<-iii\.

A Miiniiiary ol ihr phNsiial < harMcK-riMiis olciich edaphic hab-ilat i\ picsc-ntfd in I able I. Nfainh »uila<r lrni|><-raMii('« werealwaNi towel ih.in an)l>u-ni ail lriii|>rialiiir al i lu'si h^l^hl ic"KardlcM i>t ihr ^priinalophMr oi M-avin involved. In tonnasl «>lhr(la»<tical %,ill iiiat\h liu-iaiiiir. ihr |R hahii.il wa« ( hai.i(lrti/r<lbv ihr liiKhrM inai\h Miitair %alinil\ {M%, on 'Jl |iiii<-) and theSI' h.ihiiai |M><>M-\«<-d the lourM ricvalion. Ihr US h.ihilat w,i»alv> (h.iiadrri/cd ])\ h>|KMt,ilitiii\ (.*>?'«< on 21 |iinr) and |MIV*r>M-<l ihr highrM rlrvalion. I hr rrinainiiiK ihirr %|H'inialoph\lc/onr\ ncvrr l)rc(iiiic h\|K-M.ihnc (>4.'i%r—•wr i r l . '.») and wereinlriinriliair with rr^ard lo rlrvaliiin. I'rirninal <ih<M(l» charaf-irii /rd all «|K'rinaiophyle« except DS and SO, Winiei diehack "Ilhe annual »hiMii» refilled in exirenirK high li^hi rnrrnirn reach-ing lhe inar«h muriate in January (iiiraMitrd \^ |aiiiiar\). amithi% i« reflrcied hv lhe mean value* (oi all ihire liKhl wavelenKi''hancN fM-in(< KrralrtI lor DS and SO l.iK>il eiiri){\ leaihiiiK '•""inar»h suilaie wa< rrlaliveK (oiiMani ihiouKhoiil ihe \ear in ihr

ihree hal>itai%. Ihere wa» gieal vaiialion in «ano|>>hl lielween e<laphii hahiiaK. since eac h Mip|Miried a ditlrreiil

.i|>ermalophvle »|)rcies. Sjiil nioisiiiir was hiKhrM iM'iiralh ihr JRcanopy, even though uliniit was gTc-aiesi here. Oiihophosphateiilicl amniDiiia nilrogen loiurnlralions in ihr inlrtsiiii.il waterexhil>ilrd K>e-« seasonal vaiiation. I hr loinirr was highrst on 11Aptil loi all hatiiiats rxcrpi DS ('Jl June insirad). whrtras ihrl.iitrr showed pcytV values (in either I t OIIOIM-I or I.S )atiuar«,Miiii>Mo|>c examination ol the srdiinrnis (up|>er I inni) rrvealetlihal the marsh »uri,ice ai e,ich edaphic hahitai in cotn|Mised ex-«luMvel> iif t la>s and hue sill (mud). as well as siKnilii ant amountsol organic dehiis (onlril)uled hv lhe s|M-tmatoph>tr canopies. Inad<hlton. the rhi/omes ol SO weie pat I ol ihr mud waier niier-l.ue. Scrapings ot the ttiarsh sutlace duting collectiotis tevralecla great numlH-t ol xiahle. sittall |M-iui.itr di,iloitis and ven cKca-liotial coloittrs and hiattients ol hluegteen algar. I hr sttuctutalchat,ulertsti<s ot ihe ed.iphii hluegieen algal coinmutnties ol(iravelitie Ba\ Matsh ate the snhjrcts ot a vpataie pa|)ei (7),

MAIKRlAt.S AM) MHIIODS

Kdaphi* diatoms were crtllecled trom the ttve edaphic hal>it.il»on 11 Octolx-r I'.tTti. IS Januar*. I I Aptil. Jl |niir I',177, hytaking sedittieni core* ol thr ittatsh. I hese dates wete iho»en locorrespond lo ihc midpointt ol ihc traditiotial lour M-a»c»ns, On

468

MIS.SIS,SIPP1 SALT M.ARSH I>I.\ rOMS 409

Flti. I. M.i|> tu>uitlK rcl.iiiiitiship ol (;ravrlinc Bay Manth u>the ^lilui<l^ippi (;iil| (.IMM ;IIII| .nlj^Krnl uairr ni . i«o .

«l.iic. chrcc rpplicatc Miiiplrs were taken in each sperm-atophMc /ciiir. lur a u>l.il ol 1>() Minplcs. I lu- lrilii)i<|iic<> lor v p -uiation ol the ciLiphii ili.iioiiiN lioni ilic vdiiiu-ni tort- ami thepi<'|>.ir.ilion ol |K-IIII.IMCIII Ihr.ix tnotinis h.ivr IH-CMI (IrMiiliril.a* wc-11 as rcaMiiis given lot ilir .ip|K-araii(c ol nonnioiilc taxa onllu- ptc'paird sliilrs (•<). FA.UIU .MMI ilialoiii v.ilvrs w n c toiitileiland id<-nlili<-d lo <|K-«ic% or varietal rank in each sample. .Miera s.iinple had In-eti atiaK/ed taxotioniualU. its N|>etirs di\ersitvv\a> i.ihiil.iied li\ the Shannon-Wienct inloinuiiioii index (H'l.Ihe MMKtnie ol scleiied pans ol e<laphu iliatitm loitiinnnitiesWas loinpateil l» means ol a siiinlattt\ index (.SIMI) pro|M)setll>\ Si.imlet (N). I he loiinulation aiul pio|K-rtie!> ol M \ l | weredeMtilK-<l in an earlier jwiK-r ('.»). I o lelate ol)servi-<l diltetetuesit) (<>tiiinutiit\ sttiuttirc lo rtivironinental lattors a multipleregression analvsis was iK-rlormeil throt•^ll use ol ihe I.I.S-SK-l.H'.y paika^e<levelo[K-il l» the (lomputei .S«ienieand SiaiisiioDepartment at Mississippi Slate I nivetsit>. .SIMI served as thetle|)«-ndenl vaiialile aiwl alisohite dil letemes in the ten en\iron-iiu'tital lailois listed in lable I as the inde|M-tident vatiahles.Ihiee addilioii.tl inde|K'n4lent vaiialiles uere i iealed lo lesl tor

atu seauinal dilieiciues in the V-iiitetiepi. in lieu ol runninglour M-paiate legiessioiis. Ihe niimlH-t ol oliservatioiis was Slid»iiue MMl values lor (om|>.irisons IHMWM-II repli<aie s.iiiiplesWere iioi used iti the atialysis. thus eliminating (>() (4 x IS) ol>-

i

RIlSt'l-TS

A lol.il nf n o laxa were riTn^ni/rd .is (ntisiiiu-ciils nt the cd.iphK di.itntn llnia nl Citavclinc BayMarsh (I able 'J). A Inw nl 79 were meinlxTs o f theJR (Dintnttnilv while a \\'mU aiH9 wotr rtuoiiiiliMcdiHtKMth the D.S t.iitnp\. Kcstiutcd t.ix.i wetr irla-livflv U\v, nutiilHMin>r nitl\ sevrti. A irstiittrd taxnnis (lcliitcd as .Ul()llluitt^ tot at least teti indivichialsiti ntie (ntiiMuitiitx. hut at the sattu- titne In-itin (t)tn-pletelv alisetit Irntti the tetn.lit1itt^ Intn. l l ie 1)Scniiitiiutiitv iiu hided live siu li t.ixa. and these ac-cntitited lni ite.n l\ niio nut nf every live individualsmutited hetieath that p.ntitular sptMiiiatnph\te.Ihe (Intniii.iiit ihiee t.ixa in eatli (otntiiuiiitx were

as Inllnws: DS—Xat'iculti stitniitola. S'<i. trifmtirtiitit.•\'iti.\rhui Jrustutum; SC)—,i(htuiiitJir\ titurrolntti vai.<tut>in, Sa. tripumUitn, Xi. psnuttHimfihioxys: JR^^.

4.3

4.2

4.1

4.0

3.9

H.3.83.7

3.6

3.5

3.4

3.3

N>13

Kni. '.'. (.omparison ol siN-ties diversitx (IT •= bitvindiMduallheiwern e<laphit <liatom rommunities hv t-SI) leM iP « O.H.S):least si)(nilitant intervals plolteil aroiinit e.Hh <omniiinitv meanlor|K-ti<Ml N(XtolH-i l'.)7l) through L>I June 1977; j|>l>rrvMtK>n»M in ickl.

liitnroltUn var. dutm. Sa. .satinirttla. .\a. trifniticlafa;^A—.\ti. tnftuiirtala. Si. ithttLsa var. nana, .\i. psrtt-iloamphioxy.\: SP—A. haurkiatia. .\a. satitianim. .Vi.f>\fUit<Himf>hioxy.\. Savinila Iripunrlata was the mnstalHiiulaiit taxnti in OS. .SO. |R and S.\ cniiiinuiiities.wlieieas .Vi. fisniitonmphioxy^ was in the SP habitat..\fix-irutn tnpuuctata arcountetl for 21.5% nf the3().(K)(» indivichials (oiinted during the stud\ vsith.-{. tmiffotntu \.\v. duhia the secntid iiinst ahuiidatitIxneath the two tallest siKiiiiatnplivtes—SO and JR.

Values l«)i speties <liveisitv (H') atid tlie iiumlior<»f taxa (S) in a sample of ."lOO valves were stibjtTtedtn a 2-wa\ ANOV'.X (edaphit habitat x date) andniiK inaiii elleits were sigtiihiatit. Ilie elltxt nfedaphit habitat was significant for ht>th H' (P <0.001) atul S (P < 0.01). whereas the effect of date

1 ARl r 1 Phy^ifttl (haraftrnMtfi nf rnih niaphu hahilal of CraxfliHr«rtv ^tar^h. \U.-.Mssif>pi {H Orlnhn I<f7f>~2t Junr t^77t S » numhrtnf ttlnm>alutn.\; olkrr ahhrnialHtm as in IfxI.

SU J« SA

Manh MirfaceI (c:).Salinit\ (%r)Ijght eiiergv ^

Blue tUKt-.VKl nm)Red ((i<Ml-7(M) ntn)Far re«l (7(K»-«<KI nm)

Soil moisiure

NH.-N (MR-ai N/l>\ height (tm)

.Standing i(,t).I September I»77 (tm)

12 2M 210 22.« 23 0 21.812 2S.8 17.1 27.8 188 16.2

12 318 526 224 2. 1 17112 210 219 l.'>7 189 15112 225 2.V) \M 182 1524 t2.0 125 I.V5 12.8 12.04 28.5 2.5 25.5 7.8 9.44 525 193 812 572 284

12 56 109 146 8t 72

5 5.4 8.7 7.5 7fi 10.0

470 MICHAEL J. SULLIVAN

TABLE 2, Rrtatnv ahuntlancr (rxfrrrwrd at numt>er nf indixittuals) of fdaphir dialonu eoltrctrd from Grax'ftine Bay AfanA, .Missi\.fif>fn (t4 (kliiher1976-21 June 1977): — <• laxtm not rolUrlftt; ahltrn'mtuiiu as in text.

Tsmon

Arhnanthei haiuhana Grun.A. tanrrolala var. dubia Cirun.A luWui/u Kill/. • •»A. irmprrn M. Pcrag.AmphipTota rlrcuMola Grun..4. pulihra Bailc>'A. umilu HUM,Amphora angwtta var, tihlonf^rlttt Grun.A. foffrarformu (Ag.) Kiitz.A. rxigua Cirrg.A. granulala Cirrg.A. utbvt Salah ,,A. lenrmma HuM, •Aruiuluf htiUuwi .Simon.BanlUirui paratlnxa CimrlinCalinun wrUii (W. Sm.) HcrulcyCamfnltntra tilrxandrua SdbhC. cymbrtlifnrmu {\. S.) (JTUn. , .,CiKConru ilurultntin Hu«t,C. u-ulrllum var. panv Cirun.CyftottUa ra.\pui Grun. , ,,,,i.^.„, , ,„C. mmrghinutna Kuiz.C. i/»i<»t-ui»i Brightwcll ' , ' -Cymatmtra hrlgua Cirun. ; •' -CimhrUa pumlla Cirun.DmiutUa >uhlili\ Cirun, ^Dimerrgramma minor (Greg.) Ralfs 'Chplrmru tlliptwa (Kiitz.) C:l, :[i mnlitrrranra (Cirun.) Gl,D. p\rutlm<alis Hu:«l.fragilana /fritn<m HUM.F. pinrutia Khr,Fnulultn ttivmotrtrva (Gl.) HuM.Cyrmigma halltrum (Khr.) Rjbh.C. HKUTum (W. Sm.) Cirill, Jt Ht-nfr.C, Mitjuum (Cirun.) B<isrrC tibsturum (W. Sm.) Cirifl. & H r n i r .G. pnwnu (Cirun.) H U M ,Mtulogltna pumtla (Cirun.) C l,,\tfltnira luUala (Khr ) Kutz.Saivula ahuntla HuM.\ . Ofcomtxla H U M .iV. arifuorni HuM.,V alpha C;l.\ aurtcttltila HUM,iV. btntttlultivi .Sulltv. k Rrim.S. arrumtnia Mri»trrS. crruihuTgmMs KrasskeS. durrtti HUM, • .\ . duJrvi Patr.S.flanalua Cirun.S. hudumu Grun.S. intrria Grun.,V tnrtmpt)%ila HagrUtrin\ , menwului Vhum. , ,•,S. mutua var, cohna (Hiliir) Grun,N. no^nu Siinfin,S. obfolrui HUM.S. prrrgnna (Khr.) KulZ..V. phyllfpla Kiitz..V. pfrutittrrtuxtroitrts HuU.

S. rrgultini HuM.N. lattnttrum Cirun.\ . taltnuDla HUM.,V. ittbtmlans CiilirnS. latttxa Hohn k llrllrrm.S. tnpundata (Mull.) BoryN. jurrrruu Grun,

287364269

•^• —

S3

24335222

4110295

32

—1

<--.' .„ ,.—"'-

1• - • , t

.:: s»411

s•—26— •

—

•mm

IS

7421

10^-..'S

11

S4S17,~>7

119—S914

1589S

'' _SS16SI6

SI627

17

814

so

1.57833

28—

S—2

12.i-r 2 '

11691

1411862—6

—

—1

21• :. ; • . 9 -

:, 2 S '" •

102I

— . .

75 '- ;- 28• . s ,

~* ...—

I ^1

" , • • • I " •

S68 - - '

24^ " • ' • '

27

• , • , . . . . _ _

14

IS_

• , 26

267

2S4

422

1 - 'I162

1308I

17873

J«

244976

2——

14

10—

1054I

523745—

" " " "• 6'"

S1

5846 .

:.. IJ .. _.

1983

: • —

SO1

169—

1. 2

98, ',

—

J54S

- • —

49. _-.

5—22—>

22. ' ^

. . '228

- '- ' 87• ' _ r '

12SS9

I4'i

4ttl7

1303—

SA

168226

251

——

131

198

114

352729

2—2

—25

• ' ' & •

61

632

—45194

• ^

• _

S—•.—9

' ' 4— '

I1236—

S_49

41

_—.

115

—5810

4115II29

B216

Hi18

20593

SP

567253

Ifi2

—34

—15

1895

—9

217595

—14—

59

•' 7 -

22—44

5—442318121IS

11s6

20147

2

_

7—

7—.3689

3234

SSs

545

153^ 1f 1

15()957

7

49319

Manh

14232652

971234

115642

84341

5120509234

4121

5315812422t>61

7418

123

KM17351

IHI145

1635888

1673

2.'>0•ft'

360

34578

541

11936

2981728

134440

340

242fit)

2182

70924

l3(iO41

645625 _

Mississirn SALI MARSH DIAIOMS 471

TABLE 2. Contmutd.

laxim

iV. tmlrtfti Grun.S'atnruta sp. # 1Siturhut anguttins W. Sm.Af, apiruhila (Greg.) (;r\in. . . ^ ,Af. Mnhnia var. amlngim Ntang.Af. cummuiin var. hyalina LundAf. disMpnlii (Kutz.) Grun .Af. rfii/iw \V. Sin. •''Af. rpuhrmuiiiifs Grun. ;.Af.yi/i/..rm« (W. Sin.) Husl.N.fruslulum (KiiU.) (irun.Af. gtana Hohii & Hcllcrm.Af. graiiulala ( i run.Af. Aun/fnrifo Grun.N. hw,lrdtiana SalahAf. iann.i Husl .Af. tn-ulfn.\i.\ (W. Sm.) V. H.Af. liimiiiana var. suhlttu ( i run.Af. mirriKrphala ( i iuii .Af. nh\iiliak\ HuM.Af. ohiwLti W. Sill.Af. ohttna var. nana Grun. • t,Af. pandunformts tircg.Af. pandun/urmis var. rimtinua Cinin.Af, pan'ula l.cwisAf. ^m'rrsn (irun.Af, pltma \V. Sm. • :N. p\ruiti>iimphiax\.i Hu»l. , -. i .Af. rrrla H a n t / .Af. scalaris (Khr.) W. S m .Af. M/fm<i ( K u i / ) W. Sm. 'Af. si>riali.\ v.ir. nuiiti/iriKU ( i r u n . ' 'Af. Inhliimrlta Hani / .Af. iiiur^t Hum.•V. xittrra var. .ui/inarum Grun.A'WurAia sp. #1Oprphora paafira ((irun.) Pclil0. ptin>a ((irun.) KrasskrO. srhuwlui ((irun.) IVtitflfUrostgma dL\tmgUfndum Huxl.''. .lalitiamm (irun.Iflinpnlmtui gihhrnila (Khr.) Mull.Slauronru amphiaxys (Urg.S, amphtnxyy var. iiA/u,«i HriulcyS, .M/IIM W . Sin.Sunrrtta stnalula lurpin^yirdra imri/irii.i W. Sm.ThtitmnoMTa fffrnlnta (l.hr.) Cl.Ctoputonns trpidoplrra (»rcg. "T. i;itm (W. Sm.) (.1.

lotal luiinltrr laxa <Number icMriticd laxj% contribution of rcMrictrd laxa

DS

. ^

1237

825^35

25

195725

742997

1275

217

2S38^29—

54

49

—4

1231120

229

—51

—2815

142

28—

9——

895

17.2

so

214—2

382020—.—

120152_—12

3—16

262112 -309

217

918

552

7928 "

4_ .

2——

113 ;311

—21—.

24

341

^

87

—

13 4 1 •

7

148• i

83

—55 -

4271

_ '18

16

2310

314^ *

1I " ' ••

531

1603

_154

1

221

15

1

38

6I

14, —

79'11.0

SA

64

r 1 1• 1

12i ^. . ^

232

,,• 1_6

_ • »

^ _

78454

„-,,- - . . 15. _ ^

4615

141

811

11592^_,

22S11

3992

194

1

14

81

—

SP

21

_11

^ ^3 '

J l " S3:• 266 t

8_ _ : •

^ _

S

33473

275

' _4

237

IIMM

3tl7230

• „ , . _ _ - .

, 74

• 1 - T

• 4 •

35•• . • ; 6

• ' 5 ' ';)' 6

185

133

3225

8810.6

Manh

3w~ 6 8 • •

* 49. 1025324

ri53

5 •"

40.51602

10 .429141127

'i 43 -^ ^ •; 7 .'

1521537

IL»81588, 7

. . : . 7.;;_

23017

• 252710 , % ,

371- • " 6 2 7 -'-

. . . I I - T

J O I 1• : ' 4 . ,

' • 9 - • • ' "

* 15

10«7

••-;.- : i a : - ;

• ' ' " ' 4 3 •• • '

••' \ 1 ' 2 5 :• " '

, 2!75''4-i • ~

.' / :»' '- • - • "

lOS•- ^ . s •

8119

73.8

Was siKiufuant only for .S (P < O.OO.")). F.xatninationol Fi^s. 'J and ;i iiuhcaic thai rtlaphu diaiom toni-nuiiiiiv divorsitv \\as highrM in \hv DS and .SI' hah-•lais. lowest in the SA and JR hahitats. aiul intcr-•Ticdiatf hencadi the SO tanopv. H' lanncil from3.318 «o 4.24(') (Fig. 2). wluMcas S ranged from 3.'i.3•o 43.5 (Fij{. 8). U'iih regard to the date efle« t. S wasK^catesl on 14 April and statistically e(|iiivalent forthe remaining ihiec collectioti dates.

I ahle 3 lisis values ol SIMI lor comparisons of allconimiinily pairs on each of the four collectiondates. Values of SI.Vll were extremelv variahle.

ranging from a low of 0.242 to a high of 0.976.However, 27 of the 40 SIMI values were greaterthan O.fiOO, indicating that in genetal the commu-nities were more structuralU similar than dissimilar(i.e., the majority of community piiirs jjossessedgreater than r>0' of the maximum similarii\ |>ossi-i)le). It is prohahlv safe to conclude that the com-muiiitv pairs structuialh most similar were: SC) &|R and .SO &• S.A; whereas the least similar (or mostdissimilar) were: DS & SA. DS & SP. |R &• SP.

Ihe multiple regression of the IS indefx'ndentvariables on SI.MI was statisiicall) signihcant (F =

472 MICHAEL J.SULLIVAN

44

43

43

41

40

39

38

3 7

36

3S

Ku.. 3. (.<irii|uiiM>ii III IIUIIIIH-I of l.ix.1 iii a vi i i ipic |S) IK--Iwrrti n l a p h i t i l U l o m cc>mniuiiitir« bii I..SI> irM if <• II.(I.*!): lr.iM

aiit interval!! p lo l l rd an iu i id c a t h (f>iniiiunil> mean lor14 Ottobrr 1976 through 21 June 1977: al>breviationi as

in text.

12.6 for 13 and 34<i «legrec$ of frcctlotn); however,the coffluicnl of (IfirrtiiiiiiUion, or R*. was only0.322 and ihc siatidard error of the cstitiiaic was0.180. I able 4 lists /-values (or ilic partial regressiotitcK'fhiienls asMKtatefi with eath of the 13 iri(le[HMi-ilctii variables. For 34(> residual degrees ol Ireedotiia /-value must Ixf greater than 1.97 for a given in-cle|XMi(leni variable to IK- ol value iti preclittingSI MI (i.e., its partial regression coefficient is signif-itatiily different from zero al P = O.().'>). Kxattiina-tioti ol Table 4 reveals thai dijjerfucrs aitiotigsiedapbic habitats iti far red ligbt energy, soil mois-ture, atnmonia tiitrogeii atid elevation are signifi-cant factors iti pr<Mluting structural dilferetices inthe edaphir diatotn (tmimunities of (itavelitie BavMarsh. Ihe /-values associated with the three indi-cator variables were all significanl; tlierefore, theY-irnerccpt for the riuxlel varies wilh the four sea-

1 AkUC 9. SlalTVt nf Mmitfinh fiilufy' (StSIt) romfntnnK ritiiphir itmlomlommuntttn of Oravrtinf Hm Mnr\h. .MiMutifipi ( / ¥ OiUthrr tf7h-2tJunf t977): ali iiUun utO'; atthrntatiotu as in Int.

pmn

DS v». s oDSv».JRDS*s,SADS VI. SP

S()v».JRSO v». .SASO v». SPJR vs. SAJRv» .SPSA v» SP

14 (Vi

4483973153287855985308515O4425

376713288545577976673494492605

M April

694700554397705856528555420814

XI June

769912550242881896598683335837

I ABt> •!. Siimnmn of l\<utur\ fur muttiptr rrgrfnion of tl indrpm-lUnl varuMf\ on \imiliinh) inilrx (StMt):fii\l 10 vanalilrs inrrnpondUl ah\i>lulr (lijjrTrncfi in rniiriinmrnint fiuUifi lislrit in tAltl.t /,' '"•»'} arr tmtiealor mnahtn. Set trxt for Jurthrr drl<iit\.

Indrprtxlml varMUr (•value

yHlur li^htKc-<l liK>itKir red light

On ho-1'NUrNCanopy heightKlrvaiionScavMi ISeaMin 2Season 3

0.91.00.3L44.13.91.52.11.87.97.25.44.4

• Each IHMI >atM ralriilrilwl titrt Oim rrphcMn prarfrd la yiiM * •tngle umplr.

sons satnplecl. Sitnple correlation ctK-fltiieiits for thelinear regtessiot) of itidividiial itulepettdent vari-ables on SI MI were relatively low—the three highestvalues iK'ing asstniated witb elevatioti (-0.35), can-opy height (-0.22) atul anunotiia nitrogen ( - 0 . Ui)-Situe the partial regressioti coelficietit for canopybeigbt was almost statistitallv sigtiifuatit (/ = i-^)atid it out|HTfortne<l all other variables except ele-vation in the litiear regression atialysis, otte ttiigbttetilatively regard tbis factor as Iwitig a sigttilicantotie. Finally, the low R' value for ibe multipletc-gtessioti attalssis is due ut tbe low degree ol tor-relation between atiy one itulependent variable ati<lSIMI.

l>I.SC:U!i.SK)N

Ihe edapbif diatotn (otnmutiities of CtavelitifBav Marsh, although cerlaitily not idenlical iti eithera taxotiotnit or statistical sense, share cerlaitt strik-ing tharacteristics iti cotiittion with otte anotber aswell as tliose (omtiuuiities studietl previously by tbeauthor in Delaware and New Jersey salt tiiarsbes(9.11). I be struclural cliaratteristics of edapbif clia-totit totnttiutiities InMieatb spertnatopb\te tanopit**on ibe same atul (lilferetit maisbes ate (|ualitativelysitnilar: liowever, (|uatititative differentes in variousstructutal parametets ttiay IK* large. The <liscussio»to follow will (l(Muttietit tbese parallels in diatotncotittiuinity structure iK-tieatb salt tiiarsb spertnato-pbyies and attetnpt to tn.ike some geiierali/alio»^oti tbis ttituli tieglette<l stibject.

t)iiiliim jUiui. A total ol 119 taxa were fountl in ibepresetil study whereas 101 and 91 were etttoi"''teied iti Delaware and New Jersey resjM-ctiveU. I hisreflcx;ts tbe greater iiumlxr of s[KTttiato|)byte ZOIK'S

satTipled in Mississippi as totiipatcd to tbe tliree inDelaware atul two iti New |etse\ . Ibese tttitnlnMSmay seetti stnall iti cottipatisoti to tnost Itesbwatetsystems, but tbis may l)e explaitied by tlie liighlvtlynatiiic nature of salt marsbes. I itial inutulation,pericKlic clesitcatioti of tbe marsh suilace, atul pif*cipitation itiletati lo create at) enviiontiietil iti wbicb

MISSISSIl'l'I S.\Lt M. RSH t)lA IOMS 473

only fiirvh;ilinc (li.iloin taxa mav survive. One ex-cepticin to this jjciu-rali/aiion wliirh would iciul loprove the rule was the SP conniiunity on the NewJcist'v marsh, whore a large IUIIIIIKM- of laxa coex-isted lor six months of ilie \ear when tnarslj surfacesaliniiv KMuaiiK-d IK-IOW 4%C. Such a salinily regimein any other ed.ipliic habitat studied to date wouldbe atypical at Ix-st.

With llie exteption of Fnifrilarui Ifptostaurou var.duhin ((>run.) Hust. atul Mrlosha uummuloiilfs .Ag. inthe SP (ommunity of New Jersey, all dominant taxalisted lor a specific edaphic diatom coinmuiiitv pos-sess a well <U'Vflope<l taphe s\stein on at least onevaKc. The iM)ssessi«)n of a ItKomotion s\stetn hasobvious advantages in an environment where tie-position of sediitietits is a continual piiKess and ini-ciomadients in inoistuie atul essential gtowth ele-'iients rnay exist. Ihis helps expl.iiii the dominanceol the flora by Savkuln and \itzsrhia sjx'cies in allwit marshes studied to date. I he singlt- most ahun-datu (li.itonj on the Mississippi and New Jeisey"larshes \v;is S'dx'iniln tri/fiinrttitfi. Acc:orclin}{ lo Pai-rit k (5), this taxon is synonymous with ,V. f;rii4ili\ Khr.hi a(l(litiot),A'. trifmncttita was abundant i>eneath iheI)S and clwarl S.'\ canopies on the marsh proper inlk"laware. Kxtej)t lot the Frdf^hinn and Mrloura•;<xa listed liete. the doniitiant taxa on the New Jer-sey niatsh wete among the \'S most abundant oneson the Mississippi marsh. Futtherni(»te. all of the•lominant taxa of the Del.iware matsli. except .V«-^'iruld s/Hutinrtrnsis Sulliv. X: Reim.. were constituentsof al Irast one of tbe five Mississippi comttumities.Htiall), 100 of the 119 dialotn t.ixa encounteted on'lie Nlississippi m.ush were ;ilso lollctted IH-IUMIII''permatopliNte <atiopies in the Delaware atul/or• ew Jersey m.iish. il.ised «>ti the (|u.ilitative tuitureof the tiata presetited (i.e., kituls of t.ixa present),otie c;m hvpothesi/e that further work in other saltiiiaishes m.iy leve.il the existeiue. witfiin as \et uti-'lefined limits, of a single basic edaphic diatom coin-oiiinitv iiuligetunis to Atlantic and (lulf coast salt"Kirshes. Ihis ,ippeats to be the c.ise for edaphicoluegieen algal (onnnunities in s.ilt m.nshes of thesegeographic regions (t),7). Since the tiuinlKM «)f dia-••>m laxa com|Mising a comtnunitv is nuuh greater'I'an that of bluegieen algae, and dotninance b\ a''"ij le t.ixon less pronoiuued in llie foinuT group,"He can also hyj»<»thesi/e that mcKlilicatiotis of thisbasic salt tnaish diatom comtnunitv exist in dif fetenttiiaishes. Wh.itevei the case, the avail.ible il.ita in-dicate th.it sin.ill. motile, peim.ite di.ittiins ate thedominant life forms withiti sediments iK-neath ihe'ipermatophyte canopies, and that a significant nutn-'H'r of laxa exhibit fidelitv lo this s|>eci.ili/e(J h.ibitat"» three widelv sep.iiated salt in.ushes. Fidelity is•lot iise«l here in its stiiitesi sense liut r.itlier to coii-H'y the idea ih,it ceit,iin di.iiom taxa mav well IK><leiii/ens of all coastal vilt nuushes (e.g., Drutkula'^'ihtilis, .\mf)htnn rxifpiii. Siii'itula stilwuola). l.,istK,•lie author wishes to stress most stiongly thai a plant

S(Kiological approach to the study of salt marsh dia-toms is nol iK'ing adv»)cated. Ihe limitations of uti-li/itig otilv this approach have Ix-en aptly pointetl• Hit bv Mclntire and M<H»rc (4). who instead detaila mote objective analysis of ihe distribution of ma-rine iK-nthic <Iiat(>ms in space and lime based on uni-atid nmltivariate statistics. Ihe latter approachholds the otilv hope for screening large data basesfor interpietable biologicat itiformation. whereasihe former tnerely provides a laln-I for excee<linglvcotiiplex cotnmunities ofOrgatiisms.

Restricte<l taxa (i.e., taxa ass«xiated with a singlespermatophvte in the marsh under study) were leastptevalent in Mississippi. interme<liaie in Delaware.antl extremely high in iuimlH*r in New Jersey. Ht)w-ever, in New Jersey only twt> spt-rmatopfixtes weresampled (S.\, SP) aiitl resirictetl taxa acct)utitetl foronly l().3'/f of all intlividuals ctnmied t>ver ihe <meyear studv. Basically, the presence of restiicietl taxatells thai significant tlifferciucs exist anutngst theetlaphic h.ibit.its lieneath the various spermato-phvtes of a (Hirtirular marsh, at leasl as far as theetlaphic tliatt)ins are ct>tuertied. Ati alternative ex-planation is that mtire satnples need to lx- taken aiulexamitu'tl tt> <letect ihese st)-calleil lestrittetl taxa.

Community liivn.sity. .Mtluiugh statistic.iUv signifi-cant tliflerences were demonstratett Ix-iween thefive Mississippi communities with regarti It) the twt>tliversitv statistics empltned, all such values were rel-ativeU high antl langetl from .i.,14S itt •l.'24(i ft)rsjHTies tliveisity (\V) antl frt)m 35.3 to 43.5 ft)r thenumlK-r of taxa in a sample (S). C.t)rresj>t)ntlitigt.mges for e(l.i|>hic tliatom cttmmunities IxMieatJisjK'rmatoplnte canopies in Del.jware antl New Jer-sey salt marshes overlap tlitJse of the Mississippicomnumities. In the Delaware marsh H' rangedfrt)m 4.034 tt) MiSS atul S frt)m rj."> it) 32.1, where-as in the New Jersev inatsh 11' rangetl from 3.955It) 4.8'J5 antl S fttini 42.(i tt) (>«).4. On ihe average,the Mississippi marsh liailx)retl slightlv less diversetliatt>m ct)mmuniiies tban tliti its nt)rtheastern coun-ieip.itts. Futther tese.itch is neetletl tt) see whethert)r iu)t Atlantic aiul (liilf ct)a.st s;ilt marshes tlifferstatisticalh with res|XHt It) sjKxies-iumilx'rs relatit)n-sliips. Where intlivitlual comiiuitiities were con-certietl, iht)se IxMieath the DS atul SPcant)pies werect)tisistetillv ihe mt)st tliverse in a particular marsh..-\ltht)ugh the latter habitat was ntx satnpleti in theDelaware stutiv, it appears ihat a mt)ie tliverseeti.iphic tli.itom ct>nmiunitv is to lx* ex|Htietl l)c-tuMth the SPcant)p\ when the S.\ habitat is sampledct)ncui rently. Reast)ns ft)r this are nt)t clear at pre-sent althtnigh testable hy|X)theses have In-en gen-eiatetl bv legressitin analyses.

lU far the ituist obvitnis antl tlistinguishing fea-ture t)f the tliversity <lata is the extremely largeamt)unt t)f inftirmation contaitietl in the structuretif etlaphic sail marsh diattim ct)minuniiies. 1 his rel-ativelv high tliveisitv exhibitetl bv the tnicrt)flt)ra isin striking contrast ui the law diversity of spcrmaio-

474 MIC:ilAHLJ. Sl'l.LIVAN

pbytes in most cciastal salt marshes. I bus. ibc ques-tions naturally arise as to why are there so many dia-tom sprtics inhabiting ihr sedinu-ms «)! anctivironnu-ni tradiiionally considerc<l by many lo bean extremely stressful one. and. why is H' so high?I suRjfcst that the salt marsh sediments {lo not con-siiiute a stressful environment for ihe well adaptededaphic diatom (onmiunities lound iK-neaih thevarious marsh sjK'rmat<»phytes. As lo why H' valuesare so high, I further suggest that (he highly dy>namic (and again not stressful) tiature of ihc .saltmarsh sysiem never allows a single taxon lo com-pletely dominate a communiiy. Heterogeneity of thennirsh setlinjcnts creating numerous micronithesmay also IK- part of the answer. Despite ihe greatpotential inhereni in these highly tliverse (ornmii-tiities for detection and tnonitoring of salt marsheutrophication. only the author (10) and Van Raalteei al. (l!l) have rondticted field studies utilizingedaphic diatom cominuitity structure as a responsevariable to nitnigen and/or phosphorus enrichmenl.

Community similarity. A selected similarity index(SI.MI) has bet-n eniployecl lo objectively measurethe structural similarity of any two conmiunity pairsin all siu<lies conducted by ihe author. SIMI valuesfor the Mississippi marsh were extremely variable:however, the lowest values teiiflefl to «xTur whenihe n s ctmmiunity was a part ol the comparison.Restiicted taxa were a signifiiatit com|x>nent of thisc<i(niiiuiti(y, \'ilz.vhM psrufifwmphtnxy^ was dominantor abundatit in all coimnunities except that assini-aied with DS where it was completely abseni, andfK>lh \'. obudialvi aiul ,V. ohima var. nana showedgreatly reduced abundances Ix-low this particularcanopy. In addition. Sage atid Sullivan (7) found thelowest SINfl values asuxiated with the edaphic blue-green algal communitv iK'neath ihe D.S canopy onthis same marsh. SIMI values for the Delaware andNew Jersey studies were rather lc»w, and high, re-spectively, but comparisons with the present siudyarc dilTicult to make lx-cause values for the two ear-lier stu«lies were calculated on a yearly liasis insleadof monthly or even sc*asonally. One p>ini can Ix-made however; that no two edaphic sail tnarsh dia-tom communities possess a statistically idenlicalstructure. SIVH values and the sup|M>rting laxonom-ic and «liversitv data convincingly argue in lav()r ofthis view{M>int. In contrast, AmsfX)ker (I) loutid thata sloping ixMch transect supported a single, homo-geneous epipvimmic diatom community. An iden-tical result was lound for the epiphytic diaiom Horaof Ruppia nmntwm I,, when the leaves atid inier-nodes were sampled as separate entities (12). Inb«ch of these studies SIMI values were extremelyhigh (i.e.. >n.83()) and provided a strong basis forconclusions reached.

In the present study, four environtnental factorswere ojjcrative in accounting f«)r «lifferences in con>-nuinity structure amongst edaphic diatom conjmu-nitics, indicated by their /-values (Table 4). Why

only far re<l light was im|)<)rtant atnotig the ihtecbands measured is imknown: bowcycr, l.ipps (?>) didshow a far re<l efff<l for cultures of ilu" marineplankionic diatom t)itylum htifi^hturllii ( I . West) (Iru-now. Ihe effect was manifeste<l by a decrease in thecell <livision rale and was reversible by re<l lighl- '•would thus be interesting to test the more abundantsalt marsh diatoms for {xjssession of a phyt<Khromesystem. Two of the other etuirotmietual faciots,namely, ammonia nitrogen and soil moisture, wereweakly correlaierl (r = 0.13). Negative effi-cis of ni-trogen enrit hment on salt tnarsh diatom connnuniiystructure have Ix-eti demonstrated iti two intlepeti-dent studies (10,Hi). Soil moisture is a detertnitiitigfactor of the concetitration of IHUII essential antliioneNseiitial compoutids in the interstitial waterbatliitig ihe diatom unitells. Klevation was charac-terized by the highest /-value atid explained moreof the varialioti in SIMI than atiy other indfjMMuk'nlvariable. It was surprising however that «-lfvationwas so poorly correlated with all other itulepctidctitvariables. .Vevorthelevs. a multiple regression withSIMI as the dejKMuleni vatiable in the Delaw.itestudv also i<letitified elevational (liflftiMu<-s U-tweenhabitats as sigtiilicant iti accounting for structuraldifferences amongst diatom cotntminitics. In ad(ti'lion, structural diiierf/ires wrrealso related Jo tem-perature dillfretues and interaclions betweenedaplii( diatoms and iilamenious green and blue-green algae in this earlier study, the iilamenlousalgae so abundant in certain edaphic habiials of theDelaware marsh were for the moM part complfielyabsent it) ihe Mississip|)i matsh. Sitice onlv salinitywas measured and a single SIMI value calculated itithe New Jersey siudv, tlie former variable was re-gressed against two diversity statistics. .Salitiiiy ex-plained 71% of the variation iti the number ol clia-lotn taxa in a satnple benealh the SI' canopy-Neither multiple regression analysis discussetl piC"viouslv found s.ilinitv to Ix' an im|x)rtatit factor itiaccounting lor struclural dillereiues. and the ^\^'-cialized tiature of the SP liabit.it in New Jersey hasalready Ix-en diMUssed. I inalh, the model ge/)<"rat-ed by the ttiulliple regression iti the ptesent siudyexplained oiiK 'S'2'^ of the variabilii\ in SIMI. thusleaving JiH'/f utiexptained. i'resumably the l.itter isexplained by physical factors not measured, biolog-ical ititetac tions iH-lween the edaphic diatoms them-selves and other soil biota, and purely stochasticprcMcsM-s. (ioiisidering the complexity of theedaphic diatom communities and their M'dimentavyenvircmmenis one shoulil iH-rbaps be s.itisfied with"explaining" :V27t of ihe variability, since the sailtnarsh s\stem is an exceedingly dynamic one andknowledge of its bioiic and abiotic components is ola preliminary nature at Ix-st, .As always the need f<>'further research is apparent, especially those pt«>-grams designed to ex|x*rimentallv tc-st hypothesesg e n e r a t e d b y lx> lh . s i / n p l e an<l ( < ; r n p l e x r i t i a lanalyses.

MISSISSiriM S.XLI M.ARSH 1)I.\ IOM.S 475

1 am csiH-tiallv uriiiclul lo Dr. Ijonri .\. F.lciitcrius for h» kiiid-'K'ss .mil ussisi.iiKr diirinR all fairts ol llic sliulv. l ie i>oiii(c(t oiiillio siiinpling siics M (.ravrliiio B.n M.lr^h. KCIKTOUSIV allowriliiic Use- 1)1 llll l.ilM>raiorv lanli l io al llir (".ull Cty,iM Rcsoaidil'il>oiaioi> aiiil MippliffI ihc d.ila on cicvalioii .IIKI iiiicrMilial>»aicr aiialvws. Dr. Olga IV ll.it kiic\. Coinpuicr .Viciuc and Sia-lislk* Departniciit. Mi«Ni«%ippi Sialc I'nivciMix. ixTforincd thenuiliipic icKics%i()ii aiiaUsis and provided inrorinaiion on ihc"ii-<liaMii% and inlcipielalioii ol ihc oiilpul d.ila. Ihe tiilualreview ol ihe niatiiivripi l)\ Dr. Mich.iel C. Aimpokei is imu happie« i.iied. I he work upon which this p.i|x-i IN lused was siip-l><>ileil l)\ liiniN piovided In the I'nileil Stale* Departinenl «)r''lc Interior a* aiiilioii/ed under the Water Resources RcscarthArt ol I'MvJ. as amended, and adminiMered hv ihe Waier Re-»"Ui(e« Research liiMJiule ol Mississippi. Ihis woik was doneUn.lerOWRI Piojc-»l \ o . .\0<)<l-MISS and AKrcemenl \ o H-

I. /Vms|H)ker. M. C. 1977. '1 he clisiiihuiion cirinicriiclal cpip-samiiiic diaioms on .StripiM Beach. Ui Jolla. Calilornu, USA.« M 7

pi Ui Jo«irf. Mar. 'JO:2V7-32.

2. <;alla>{her. |. I.. & Dailxr. K. C. I!»7I. I'limaiv pr.Mluctiouol edaphic algal comniiiniiies in a Delaware s,ili marsh. Um->iol. Orranogr. l<»:3<)()-.5.

3. I.ipps. M.J. l«t7.S. Ihc deierminulion c>rihc far-ird cl lci iin marine phMoplankion. /. Phyiil. 9:237-42.

A. Mclmire. C. D. & Mcwrc. \V. W. 1977. Marine liiioral dia-toms: eculotjical considcraiions. In Werner. D. IKcl.) Thr Bt-iiliifry nf Dialiinti. l'niversil\ ol (Uililornia Pix-ss. Bcrkelev.333-71.

5. Patrick. R. & Reimer. C. W. 1966. 7Ac /)M/»im if Ihr VuitniStatfs. \'ol. 1. Acad. Nal. Sci. Thiladelphi.!. Monograph No.13. ( i««pp.

6. Ralph. R. D. 1977. "Ihc Mvxophvccac of ihc mar^hcit ofMuilhern Delaware. Chrvtpnikr Sn. 18:?(I8-L»I.

7. S.igc. W\ W. &• Sullivan. M. ] 1978. Disiribmion of hluc-gre«n algae in a Mississippi (.ulf coast sail maI^h. / PhxctJ.14:333-7.

8. Slander. J. M. 1970. Divcrsiiv and Similaritv of Benlhk Fau-na off Oregon. M.S. Ilicsis. Oregon Stale L'niwriity. Cx»r-vallis. 7'J pp.

9. Sullivan. M. j . 197.'>. IKitotn cc>mmunitirs frotn a IVIawarr»all marsh. 7. I'hyoit. ll:384-«»(l.

1"- I97(i. I.ong-teini ellects of manipulating light inlcn-sitN and ntilrieni etirichmeni oti the structure ol a salt tnar^hdiatom comtiiuniiv. /. l'h\tttl. I2:2(i")-I(l.

" • 1977. Kdaphic diatom communiiics asMKiatccI withSpartitia atlrmiftora atul S. patrn\ it) N e * Icrsev. Hvirnb4iJnina

12. l',<77. .Stiiiitiiial ch.itacteiisiics ol a diatom com-nuitlil> epipliMic on Ruppui mantima H\dr,>hii<liigia .'J.1:8I-<>.

13. Van Raalte. C. 1). Valiela. I. &• I eal. J \ | I<»7fi I he c n mol lettili/alion on the s|KHies ccim^Misition oi salt mar%h <tui-totm. IValnRn. U):\-A.

J f'hyfot. 14. •47.V479 (1978)

SALlNirV EFFECTS ON GROW I H AM) I ( ) \ IN COM EM OFGOSY.IULtX l-XC.tr.n.t. \ M . \ R I \ K niNOFI..\C.EI.I..\ I E

CAUSINC; PARAI.V I IC SHEl.I.FISM I»OIS()M\C.'

AUw W. Uhitr

Department of Kisherics atul the F.tuimnment. Fisheries atul Maritir

Biological Statiott. St. Andrews. New Btniti»wick. Canada F.tiG 2X«

AB.SIRACT

optimum salinih for potrth of (^otu.uilax cxia-(liraarwl) lUilnh pvm (.npr Ann. Ma.warhusrth.

•* 30.5%f^ nnd it frron's ivrlt oxrr a ranf^f of 2()-^0%f< Itlotrrnii's stilinitirs of ll-^3'4r. (hoxrlh rates at 2-f <inil20V,r arr onty ca. Kt aud 20% trw. rfspnlivily. than ihr"I'lximum. 0.36 dii>isiomlday. Il is romidnrd untikfty thai^"tiuity fluftuatiiin.i in thr fimstat arnv> whrrr this orf^an-i w oaurs sifrnifirautty inftunue it.\ fpouth rate, thrfkir-ttyiir toxin conlrni iu (1. t"Xtav;Ua iunra.\r\ with incrras-'"j? satinity, up lo 57%^ Thncforr. ihr drfprf of loxicity</ thf orgaui.\m iu nalurr mas hr luflururrd t)\ this ruifi-''"umrulat fatior.

f^n indrx word.v diuojhtf^ettalr; Gotiyaulax: grou^lh^»tr; \uliuity; ui.Kitoxiu; laxiu coulrnt

Rl(M>ins ol" the loxic ni.iiiitc tlitxinaxctlalr Con\-rxcai<ata (Itiaartid) U.ikch oicur regularly in

1978.

casicrn Canadian waters and r>crasionallv in waters inNew Knfrl.nid (I'tiiu-d States) and the I'ttited King-dom. sonietiineN reaching "red tide" |>i(i|><)itions itithese l.i>t two areas. 1 he l)l(x)tns have considerableiittpact ott utilization ot shelllish resources and onhtiinan lualih Inxause of patalvtic shellltsh |>oison-ittg. I hev ttiav also have detrintental ellects ot) sotnemarine otgatiisms Ixnausc ol loxiii iratisler throughthe tiMul wvU (While 1977).

I titil recently the toxic ditioflagellate in the North.Atl.mtic Oceati was («)tisideied to IK' G. lamarru.s.n.. \ t«ording to l.oehlith attd I.cK-hlich (1975). how-ever, the toxic otganism is more appropriateh rc-lerrcil lo as G. rxraitila. whereas G. lamarru.m Ixr-IMUU- ttiore corrix tlv |x-rt.iitis tct a luttitoxic orgattistti.Net even ntoie t t t e t t th thete is evitletue that thisdistinctiot) has shortcottiitigs (AtulerM>n and Wall1978. Iur|>in et al. 197«). Presetith thetc is lax<>-notuic coniusion surnnnuling this complex of di-noflagellates.