DEP DEP QL 430.7 .M3 F75 1989

DEP QL 430.7 .M3 F75 1989 c2 Fritz, Lowell W; Ragone, Lisa N; Lutz, Richard A MICROSTRUCI'URE OF THE OUTER SHELL TAYER OF Rangia cuneata FROM THE DElAWARE RIVER: APPLICATIONS IN STUDIES OF POPUTATION DYNAMICS

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Microstructure of the outer Shell I.ayer of Rarqia cuneata [;.· ~,....--­

fran the Delaware River: .AWlications in studies of Pcpll.ation Dynamics

by

I.owel.l w. Fritz, Lisa M. Ragone1 ard Ridlard A. r.utz

New Jersey Agricultural Experiment station

Rutgers University

Shellfish Research I.aboratoey

P.O. Box 687

Port Norris, NJ 08349

Rl.n'm:iixj title: Shell microstructure of Rarqia cuneata

Keywords: Ramia cuneata, shell, microstructure, aqe deteJ:minatian, growth

1 Present Address: Virginia Institute of Marine SCience, Gloocester Point,

VA 23062

Property of NJDEP _ Information Resource Center

NEW JERSEY STATE LIBRARY

1111111111111111111111111111111111111111111111111111111111111111 3 3009 00622 2782

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'1he cuter shell layer of Rarpi.a cuneata (Sowel:by) is cuuposed of two

types of crossed-lamellar (CL) microstmctUJ::e: rapid-growth, deposited in

sprirg ard fall, ard slew-growth, deposited in summer, whidl conb'"POI'Xi to

seascms of relatively rapid ard slow shell growth. '!he two types of CL

microstructure were ~leon the basis of the: (1) width of 1•

lamellae: (2) an;le of deposition of 1• lamellae with respeCt to the inner

shell surface: ard (3) aDDJnt of interdigitation of 2• lamellae between

adjacent 1 • lamellae. In winter, outer layer CL microstmctUJ::e is replaced

by a sirgle prismatic bani or sublayer, ocunts of whidl were used to

detemine age.

Shell 1~ at ead1 winter prismatic bani (annulus) was measured

directly on intact valves ard used to detemine size at age. '!he b:iloodal.

distril:ution of shell ~ at the first annuluS ard peaks in· size­

specific c:try-tj ssue weight in spri.n;J arxl fall suggested that the sanpled

pep,, ation in the Del.awam River spawns twice ead1 year. At art:/ sanplirg

time, fall recz:uits were ~tely 5-10 mm smaller in shell lED!Jth than

spri.ig recz:uits of the same year-class. Von Bertal.anffy grcwth equations

were calaJlated separately for sprirg arxl fall recz:uits arxl revealed that

age specific grcwth rates of the two g:raJpS were almcst identical.

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NOTICE: This material may be protected by copyright law (Title 17 US Cod~)

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INmOWCriON

'!he wecl;e clam, Rargia cuneata (sowerby) , is a mwon inhabitant of

brackish-waters in coastal cu:eas of the Gulf of MeXico am the Atlantic

coast of the united states (Hcpkins am An:3rews 1970, Abbott 1974). An

extension of its ran;e north fran Chesapeake Bay to Delaware Bay was

recently reported (camt:s 1980) • Cold winter teapemtures in the northem

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portion of its ran;e have been attrib.rt:ed to cause mass nmtalities of B·

cuneata am may limit its distribution further north (Gallagher am Wells

1969). '!he species has m:derate camnercial importance in the sarthem

portions of its ran;;re (Wolfe am Petteway 1968), but little is :knc:Mn of its

growth am reproductive biology north of Chesapeake Bay. studies of . ~-

p:p.tlations in Potanac River, Marylarxi (Ffitzenmeyer am Dl:'cb!ck 1964)

suggest a late summer-fall spawn.in:J period arxi growth to between 35-45 mm

shell lerx:Jth in ~roximately 4 years. A similar sizejaqe relationship was

reported by Wolfe am Petteway (1968) for populations of B· cuneata in the

Neuse River, North carolina. Fairbanks (1963) reported that Rargia spawns

twice eadl year, in spr.in; arxi fall, in I.alisiana am grows to a len;Jth of

~tely 30 m in 3 years. HoWever, all previous :r:eports of B·

gmeata size at age have been based on analyses of growth lines on the

shell exterior, Wich can be unreliable guides to ilxlividual age (see lutz

am Rhoads 1980) • In this sb.r:iy, specimens of Rargia cuneata were •

. collected fran a site in the Delaware River to dete:r:mine the seasonal

growth pattem in shell microstructu:re for use in age dete:r:mination arxi,

potentially, envirormental inpact assessment.

'!he shell of Ranqia cuneata, like all species in the family Mactridae,

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4 is exttposed of three primary carbonate layers, which are: (1) an inner

?C"Plex crcssed-lamellar layer; (2) a thin pallial myostracurn, to which the

mantle is attached; am (3) an outer crossed-lamellar layer (Taylor et al.

1973) • Growth patterns in the outer layer proved to be rore valuable than

those in the inner layer for reconstruction of growth histo:cy. 'Ihe outer

shell layer, deposited by regions of the mantle ventral to the pallial

myostracum, is cxottp:lSed of first-order (1 o), secord-order (2 o) , arxi third

order (3 •) lamellae. First-order lamellae are deposited concentrically,

cq::proxima.tely parallel to the ventral shell margin. secorn-order lamellae

within eadl 1 o lamella are arrarged much like sh.in;les on a roof, with

their argle of deposition (with respect to the inner shell surface) in one

1• lamella altematin; with respect to those in adjacent 1• lamellae.

seoond-order lamellae are theJ'!!SP..lves cx:aup:lSed of 3 • lamellae, which are

'-generally poorly defined, small, lath- or red-like crystalline units joined

at their sides (see Taylor et al. 1969, 1973, carter 1980 and Dieth 1985

for further dj SOJSSion of shell microstructural tenninology) •

Specimens of RalJ1i.a c:uneata were collected by bani and with a clam rake

fran one location on the Delaware River south of New castle, DE (39 ° 37 'N;

75 o 36 'W) • Between 8 ani 38 clams were collected on each of 12 dates ...--------- - ---- - -------

-·----.bet:weEB'\ Novelltler 1985 ani March 1987 _ i (total number collected = 248) • '!he

pc:p.ll.atioo of B· cuneata was located at a depth of approximately l.0-1.5 m

at mean low water in nu::k!y-sard offshore fran subnerged mizane-peat mats.

A marsh cxottif<)Sed primarily of Rlraamites SR>· was located immediately

onshore fiat the sanplin;J site. A water sanple for salinity detennination

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(with a Guildline Autosal nvxlel 8400 salinaneter) was collected on each

sanpli.rg date. salinity ran;Jed fran o. 6 to 5. 7 ppt fran November 1985 to

Mard1 1987, with the highest salinities recorded in late SUitmer an:i fall.

Spec.imens were kept cold in transit to the lab where anilllals were

sacrificed, usually within 4 hours of collection. '!he soft tissues were

rem:wed fran the shell, an:i both the drained 'Net an:i freeze-dried total

meat weight were measured. Shell mrphcanetric measurements (len:fth -

greatest antero-posterior dimension: an:i height -greatest di.stanoe fran

the umbo to the ventral marqin) were obtained on each specimen. Shell

valves were thoroughly cleaned, intividually l"1\ll'!!bered, rinsed well with

fresh water, an:i air-dried. One of the two valves of between 8-15 spec-"

ime.ns fran each collection was imbedded in liquid casti.rg plastic ani

radially sectiot_m ,alan; the height axis usi.rg a Raytech lo-inch circular

rock saw. Acetate peels of the radial surfaces, prepared ac:::cord.i.n;J to the

methods artl.ined in Fritz ani Haven (1983), were analyzed at 40 an:i 100X

magnification on a c:x:atpJUl'Xi microscx:Jpe. Sheil growth in specified pericrls

was measured (usi.rg a calibrated ocular micraneter) alorg the surface of

maxinun growth on the acetate peels, which in Rangia cuneata is the

extemal surface of the outer shell layer (Pannella an:i MaCClintock 1968) •

Radial fracture shell sections for examination in a scaJ'l1tin.J electron

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mi.croscx:Jpe (SEM) were prepared by the general methods artl.ined by Kennish

et al. (1980). Shell fragments were glued to aluminum stubs with cyano­

acrylate cement an:l camon paint, coated with gold-palladium in a sp.Itter

coater, an:l analyzed at 20 kV acx::elerating voltage in an Hitachi S-450 SEl1.

To prepare a polished an:i etched section for SEl1 analysis, an imbedded

ani sectioned specimen was polished with dianaxi grits down to 6 Jml grit

size an:l etched in a 0.1 M EDTA solution for between o. 75,)ani 1.5 minutes.

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6 sectia'JS were t:l'lorc:u3hly dried (in air) , sputter-coated with gold-palladium

am analyzed at 20 kV in the SEM.

&a§Q"(L Microstructure of the outer crossed-Iame1lar $hell layer am Me

Determination

5easa1al differences in the micmst:ructure of the cuter crossed­

lamellar (CL) layer of Ranqia cuneata are shown in Figure 1. Specimens

collected in winter (March 1986) had a thin prismatic layer (labelled p in

Figure lA) alarg the inner surface of the cuter layer that had replaced the

CL micrcst:n1ct:ure (tcp portion of Figure lA) • Alarg its inner surface, the

~ auposition of 1;!le cuter layer varied between slightly etc:hecl prism tips

(left portion of Figure lB) ani prism tips with a thin organic (?) coati.nq

(lower right portioo of Figure lB). secom-order lamellae immecliately

above the prismatic layer were deposited al.nrJst parallel to the inner

surface of the cuter layer (defined as a small an;le of depositioo), ani 1"

lamellae are not readily ~le (Figure lA). '!his regioo of the

shell was deposited in late fall/early winter ani its poor organization am

the small depcsitia1 an;le of 2• lamellae cculd be a result of cold water

tenperatures ciurin1 this period.

By oc:ntrast, in sprirg (May 1986), 2• lamellae were an;led steeply with

respect to the imer shell surface resulti.nq in the exposure of broad faces

of sane 2 • lamellae (Figure lC) • Secxni-order lamellae te:rminated alon;J

the inner shell surface (Figure lD) in a ~cteristic stti.rgled pattern of

lobate 2• lamellae tips with their an;le of deposition altematir¥; in

adjacent 1• lamellae. '!his pattern was also obseived in specimens yc:Jlll'YJer

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than 3 years of age collected in fall (September arrl October 1986), arrl

herein will be tenned rapid-growth CL microstructure.

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Fi.rst-omer lamellae within regions of the outer layer deposited in

SllJl'IDei' (July 1986) were awroximately twice as wide (dorso-ventrally) as

those deposited in sprin:J ani fall (Figure lE). summer-deposited 1 •

lamellae were awroximately 10 J.lltl wide, while those deposited in sprin; and

fall I"anJed between 3 ani 6 J.lltl wide. First-order lamellae deposited in

summer had mre discrete dorsal ani ventral edges than those deposited in

sprin; or fall, with less interdigitation of 2° lamellae between adjacent

1 o lamellae. 5econ:l-order lamellae in st.IIt'lner-depited 1° lamellae

intersected the inner shell surface at smaller an:Jles than those formed in

spr:in:J or fall, result:in:f in a relatively SIOOOth surface cxxtlfX)Sed of

sl:la%ply an:Jled tips of 2 • lamellae (Figure lF) • 'nle pattem observed in .... .

SUIIIDer will herein be tei'Inecl the slow-growth cr., microstructure.

Differences in the seasonal microstructure of the outer layer in

sprin;Jjfall ani summer were also evident in SEM ani light microscopic ·

analyses of polished ani etched radial sections. '!he et:chi.n:J process

revealed both the broad faces of 2 o lamellae in rapid-growth cr.,

microstructure deposited in spr:in:J as well as the boun:laries of microgrowth

irx::re.nents, whidl remained as continuous ridges across the outer layer

~ perpernicular to each 1 o lamella (Figure 2A) • D:>rsal ani ventral

edges of r lamellae deposited in sprin; were not readily dist~le,

:rut were c:1istirx:t in regions deposited in summer (Figure 2B). '!he etchant

also mre clearly revealed 2 o lamella in the slow-growth than in the rapid­

growth cr., micrcstructure, i.rxticatin; that their an:Jle of deposition with

respect to the inner layer was less in the fo:nner than in the latter •

Periods of little or no growth (posSibly on the order of days) were

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represented in polished ani etched radial sections of the outer layer as

thick microgrc:Mth increment bo.Dmries, or growth cessation marks (gem;

Figure 2C) • '!he cxanpJSitian of the outer layer chan;Jecl abruptly at the

gan in Figure 2C, fran rapid-grcMth CL microstxucture precedirg it (left

portion of Figure 2C) to one resemblin;J sl~ CL microstructure

folla.dn;J it (right portion of Figure 2C) •

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'!be prismatic bani fonned in winter was readily distirgu.ishable in the

CA1t:er layer microstructure of polished and etched radial shell sections

(Figure 20) • Prismatic balm were mLIXSed of thin, rod-like columnar sub­

units, or prisms, which often had a granular texture (evidence of

dissolution; Lutz and Rhoads 1977) an their depositional faces. Winter

prismatic banis varied in thickness within an :in:tividual for different

winters and also between specimens for the ·same winter, 1:ut generally '-

ran;,ed between 3-8 JJDl• '1he micrcgraJ;il in Figure lA was taken on a specimen

collected in March 1986 am shows the· bani in the midst of fonnatian.

·AnnUal alter shell layer increments deposited in 1985 by clams of three

different aqes are shewn in Figure 3. Age and year-class (YC) of

:r:ec:ru.itment were det:emi.ned by counts of winter prismatic banis in the

art:er layer in acetate peel. replicas of polished am etched radial shell

sections. Winter prismatic banis ~ as thick dark lines Sl.1I'.t'OOI'Xied

on both sides (dorsal and ventral) by rapid-grcMth microstructure in

yamger specimens. In older specimens (or in annual increments deposited

when the clam was older than 3 years) , winter prismatic ·banis were usually

preceded (dorsal) by slc:w-grcwt:h CL microstructure fonned in fall am

followed (ventral) by rapid-grcMth CL microstructure fo:rmeci in sprin;J.

Regions of rapid and sl~ CL microstructure appear as light and dark

bams, respectively, in acetate peels. Rapid-grcMth CL micrcstl:ucture

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9 fonned a larger percentage of each annual increment in y~er (Figure JA)

than in older (Figure 3B & C) clans. FurthentDre, barx:ls of rapid~ CL

microst:ructure fo:rmed in fall became increas.i.rgly smaller with age.

Microgrcwth increment lxAlrx:laries are thin dark lines which parallel the

inner shell surface. Grc:Mth cessation marks (gan) fonned in both spr.i.rg

an::l fall (Figure 2C) ~ as distinct microgrcwth increment bol.lrxmries

in both rapid- ar¥1 slow-growth CL microstructure ( depen:lirg on the age of

the specimen) •

Winter prismatic bar¥:ls (Figure 20) were distin;Juished fran gan in

spr.i.rg or fall by: (1) the thickness, intensity an::l definition of the line;

winter prismatic bar¥:ls were thicker (dorso-ventrally), darker an::l usually

occurred as a s.i.rgle line, rather than as a series of closely-spaced, dark

microgrcwth increment l::lam:3ari.es: an::l (2) the presence of vertical lamellae -\_

separat.i.rg each columnar prism, which were often di.scemible within the

winter prismatic barn an::l were rarely present in gan (Figure 2C & D).

Alon:J the outer sheJ.l surface, however 1 gan ani Winter prismatiC banjs were very difficult to ~ fran each other •. In m::st cases, :rut not all,

the darkest rirr;Js on the shell exterior were associated with gan' s an::l not

winter prismatic barx:ls, an::l were ac::x:x:mpanied by an Wentation in the shell

exterior surface.

Pcpll.atial spxH es arxi seasonal Growth Rates

Five YC's (1981-85) were represented in the collections fran November

1985 1:hrc:u3h Mard1 1987, with the two m::st l1\ll'llei'alS be.i.rg those rec:tUited

in 1982 arxi 1984. Winter prismatic barx:1s identified in shell

microstructure were used to locate specific growth rirr;Js on the shell

exterior surface; shell len;Jth at each winter ban:l, or annulus, was then

measured directiy off the unimbeckied valve of each specimen. Shell 1~

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10 at the first annulus rarqed fran 6-25 mm in all specimens analyzed (Table

1) • Hc7.r.eTer, the Irodal. shell len;Jth at the first annulus of each YC was

either between 8-12 m, or between 20-23 mm, as shown for the 1982 arrl 1984

YC's in Figure 4. As will be disolSsed in mre detail belc:M in rel::ition to

seasonal ~ in dry tissue weight, the bimdal. len;Jth frequency at the

first annulus strorgly suggests that the species has two spaWI'lin;J periods

each year. In:lividuals with larger shell len:Jths at their first annuli

\oJere spawned earlier in the year (i.e. sprin;J) than those with smaller,

first annular shell len:Jths (spawned in fall). 'nle data in Figure 4

suggest that the fall-spawn resulted in mre successful recruitment to the

pop.llation in 1982 than the sprin;J-spawn, arrl vice-versa for 1984. ~

Because of the large differences in shell length at the first annulus

between sprin;J arxl fall recruits, growth rates of the two groups \oJere '\.

analyzed separately (Table 1) • In:lividual specimens were assigned to

either sprin;J or fall spawnin;Js of their YC if the shell length at the

first amulus was greater or less than 16 mm, respectively. Growth rates

of the two groups were al.ltart: identical in each YC, but mean shell 1~

of the fall recruits through the fifth amulus were always less than those

of the sprin;J recruits (Figure 5A). HCME!Ver, there was considerable over­

lap in the I'Clllge5 in shell lelgth at all amuli after the first (Table 1).

Growt:h equations (von Bertalanffy; IOOdification of the methods of

WalfOl'd (1946) arxl Beverton (1954) as described by Ricker (1975)) were

develqa:l separately for sprin;J arxl fall recruits (Table 2). Von

Bertalanffy growth equations have the fonn:

1 = L [1- e-K(t-to>]· t co ,

where lt is the c:atpited shell len;Jth (in mm) at time t (in years), ~ is

the asynptotic shell len;Jth, e is the base of the natural logarithm, K 'is

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11 the growth constant, ani t 0 is the hypothetical age when shell lenqth is

equal to zero. Fall recruits -were assigned an age of 0.5 years at the

first annulus, while spr.in;J recruits -were assigned an age of 1 year. L00

was larger, ani K was smaller for spr.in;J than for fall recruits. However,

with the 0.5 year difference in age, there was little difference in the

calculated size at age between the two groups (Figure 5B), suggest.in;J that

size- am age specific growth rates were irxiepen:lent of recruitment tilne.

At arry point in time that a sanple is obtained, however, the 0.5 year

difference in age between spr.in;J am fall recruits of the same YC would

result in as much as a 5-10 mm difference in shell len;Jth.

In Delaware River pc::pllations of Rangia cuneata, shell growth resumed

in mid-May 1986, after a pericxi of little or no growth in winter, ani

continued ~ mid-December 1986 (Figure 6) • Growth rates of the 1984

YC were greater in spr.in;J (fran late May "tllrrugh June) ani fall (fran mid­

september to through october) than in summer {July through August). 'Ihi.s

pattem was also reflected i.il the microstructure of the outer layer, as

described in the previous section, with ·rapid-growth CL micrcstructure

bein;; fonned in spr.in;J am fall am slow-growth CL microstJ:ucture in

summer. With inc:reasin;; ~, not only did total annual growth rates

decline {Figure 5) , tut growth rates terrled to remain low fran summer

through winter (Figure 6) • In specimens older than three years, spr.in;J was

the only season when shell growth rates were relatively rapid.

SpriD;r ani fall were also pericxis of relatively high dry tissue weight

cc:rrpared with winter ani summer (Figure 7). Mean dry tissue weights

(calculated for a 30 mm SL specimen at each sanpl.in;J date) declined fran

late 1985 "tllrrugh March 1986, tut increased slightly through April 1986.

'!he increase in mean dry tissue weight by late April occurred prior to any

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12 detectable shell growth by this time (Figure 6). Mean dry tissue weight

declined to its lo.¥e5t calculated value in late July, whidl coincided with

the ctserved decline in shell growth rates. 'Ihrough late summer arrl fall,

however, mean dry tissue weights increased rapidly to the highest

calculated value in late october. Peaks in mean dry tissue weight in both

sprin;J am fall suggest that this pop.l].ation spawned twice in 1986.

DISCIJSSION

Replacement of crossed-lamellar (CL) by prismatic microstructures

durirg periods of little or no shell growth (donnancy) has been obseJ:ved

previously in other bivalves (in Arctica islan:tica (L.) (I.lltz ani Rhoads

1980, Rq>es et ~· 1984); in Corbicu1a fluminea (MlUler) (Fritz et al •

1987); am in Astarte elliptica (Brown) (Trutschler ani samtleben 1988)).

Prismatic micrcstructures in shells are located at sites of attachment of

the soft tissues to the shell (pallial ani adductor myostraca) or may also

result, within other shell layers, fran periods of reduced oxygen tensions

within the tissues (I.lltz ani Rhoads 1980). Prolonged periods of valve

closure (which are thrught to a~ periods of donnancy) during adverse

environmental con:litions can result in the use of anaerobic metabolic

pathways by bivalve mlluscs (crenshaw ard Neff 1968, I.1ltz am Rhoads

1977). In A· islan:tica, for instance, prismatic barx3s within the inner

shell layer may result fran exterrled periods of anaerobiosis associated

with valve closure during its burrow'ing activities (Taylor 1976, I.1ltz arrl

Rhoads 1980). In Delaware River pcp.llations of Bangia cuneata, no

measurable shell growth occurred in winter, which was also the period

during which a single prismatic sublayer replaced tlle CL microstructure in

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13 the outer shell layer. At no other ti.Ire of the year -were prismatic barrls

d:Jserved in the outer shell layer, which enabled the use of coonts of

prismatic ban:ls to detennine age ani reconstruct growth histoey.

Wada (1961) ani Dieth (1985) reported that c:ystal.line units fanned

durin;J periods of slow shell growth temed to be larger ani be deposited

with greater order (in which the edges of units are m::>re clearly defined)

than those fanned durin;J periods of rapid shell growth. Results of the

present study, in which slc:w-grcMth CL microstructure was muposed of

larger, mre ordered 1 • lamellae than rapid-growth CL microstructure,

sut=PQrt their conclusions.

Measured ani c:x:rrplted shell lergths at each age "Were between 1D-25 nun

greater in the present study of Delaware River populations than in studies

of southern pop.llations of Bangia cuneata. Fairbanks (1963) used external '-

growth lines to detemine shell lergth at age in populations of B· cuneata

in I.ati.siana, while WOlfe ani Petteway (1968) detemined growth rates arrl

size at age fran d'lan;Jes in lOOdal size frequency in sequential samples from

Neuse River, North carolina populations. Both methods could have

urxierestilnate.d growth rate due to inaccuracies in inteJ:pretin;J: ( 1)

external growth lines (~ growth cessation marks fran annually­

deposited lines); ani (2) dlan;Jes in len]th-frequency distributions over

tilne (given the size differences of sprin;J- ani fall-recruits of the same

yearclass at aey point in time). 'Ihe possibility that growth rates of B·

cuneata are greater in the Delaware River than in southern pop.llations is

unlikely since this is the 100St northern pop.llation on the east coast of

North America ani shell growth is limited to only the period fran May

thro.1gh mid-December each year •

Analyses of the microstructure of the outer shell layer of Rargia

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14 cuneata revealed the growth history of in:lividual specimens. In the event

of an environmental clisturbance, such growth histories could provide some

of the "after-the-fact" data (pre- ani post-cli.st:umance seas.'Jnal ani annual

growth rates, time of growth cessation mark fonnation, size at age, changes

in outer shell layer microstructure, for exanple) necessary to quantify the

sub-lethal effects of the perturbation. F\l.rtheJ:'liD:re, growth rates can be

st:.armrdized with respect to differen:es associated with age arrl,lor season

of recruitment for unbiased estilnates of the clisturbance' s effects on the

growth of a resident bivalve species. 'Ihe shell growth patterns of three

other bivalve species, one livin;:J in freshwater (Corbicula fhnninea; Fritz

ani I.lltz 1986) am the other two fran estuarine habitats ~ arenaria

(L. ) ; Mae[k)nald ani 'Ihanas 1982) ani Mercenaria rrercena.ria (L. ) ; Kemish

ani Olsson 1975) have been used previously ·to document the effects of ...

chronic ani episodic environmental distt.u:bances. Analyses of the

microstructural shell growth patterns of B· cuneata could provide a

powerful tool for mn:itorin;:J environmental dlange ani assessin:; the :i.npact

of perturbations in the oligohaline portions of estuaries.

We thank Lisa wargo for preparin;:J the plates of mic:ogxalilS; Tim

Jacxi:>sen, Margaret Schenk, Ya-Pin;:J HU, ani Ray Grizzle ani for assistance

in c:x:>llectin;J ani worki.rq-up specimens; ani Jam Grazul ani Ridlard Triemer

for assistance in scann.in;J electron microscopy. New Jersey ~icultural

Experiment station PUblication No. D-27204-1-89 suworted by state fun.:1s

ani grants fran the New Jersey Deparbnent of Envirornnental Protection,

Division of Science an:i Research.':.

Property of NJDEP Information Resource Center

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LITERA'lURE CITED

Abbott, R. T. 1974. American Seashells: The Harine Hollusca of the ATlar.tic

and Pacific Coast:s of Nort:h America. (2n:i eel.) New YorJ~, NY: Van

Nost.ran:l Reinhold eo. 663 p.

Beverton, R. J. H. 1954. Notes on the use of theoretical nr:xiels in the

study of the dynamics of exploited fish pop.llations. u. s. Fish. Lab. ,

Beaufort:, N.C., Hisc. Contrib. 2:1-159.

carter, J. G. 1980. Envirornnental ani biological controls of bivalve shell

mineralogy ani microstructure. In Rhoads, D. C. & R. A. I..utz, eds.,

Skeletal Growth of Aquatic Organisms. New York ani London: Plenum

Press, W· 69-113.

Cc:unts, C. L. III. 1980. Rangia cuneata in an .irxiustrial water system

(Bivalvia: Mactridae). The Nautilus 94:1-2.

crenshaw, M. A. & J. M. Neff. 1969. Decalcification at the mantle-shell

interface in mlluscs. Am. Zool. 9:881-885.

Deith, M. R. 1985. '!he CCilp::sition of tidally deposited growth lines in the

shell of the edible coCkle, Cerast:oderma edule. J. Har. Biol. Ass.

U.K. 65: 573-581.

Fail:banks, L. D. 1963. Biocien¥:xJraphic studies on the clam Rangia cuneata

Gray. Tulane Stud. Zool. 10(1):3-47.

Fritz, L. W. & D. S. Haven. 1983. Hard clam, Hercenaria mercenaria: Shell

growth patterns in Chesapeake Bay. Fishery Bulletin 81:697-708.

Fritz, L. W. & R. A. I.utz. 1986. Envirornnental perturbations reflected in

internal shell growth patterns of Corbicula fluminea (Mollusca:

Bivalvia). The Veliger 28(4):401-417.

•

•

•

Fritz, L. W., L. M. Ragone, & R. A. IJ.Itz. 1987. utilization of bivalve

shells for assessment- of environmental stress. I. Corbicula fluminea.

Rept. to NJ Dept. Env. Prot., Div. science Research Contract No. c-

29526. 63 p.

Gallagher, J. L. & H. W. Wells. 1969. Northern range extension am winter

mortality of Rangia cuneata. The Nautilus 83(1):22-25.

Hopkins, S. H. & J. D. An:irews. 1970. Rangia cuneata on the Fast coast:

t:hol1sarx1 mile range extension or resurgence? Science 167:686.

16

Kennish, M. J., R. A. I1Itz & D. c. Rhoads. 1980. Preparation of acetate

peals am fractured sections for observations of growth pattems within

the bivalve shell. In Rhoads, D. C. & R. A. IJ.Itz, eds., Skeletal Growth

of Aquatic Organisms. New York am :tornon: Plenum Press, pp. 597-601. ,.. Kennish, M. J. & R. K. Olsscm. 1975. Effects of thennal disdlarges on the

microstructural growth of Hercenaria mercenaria. Environ. Geol. 1:41-

64.

IJ.Itz, R. A. & D. c. Rhoads. 1977. Anaercbiosis am a theory of growth line

fozmation. Science 198:1222-1227.

Illtz, R. A. & D. C. Rhoads~ 1980. Growth pattems within the nclluscan

shell: an over:view. In Rhoads, D. C. & R. A. IJ.Itz, eds., Skeletal

Growth of Aquatic Organisms. New York am Iomon: Plenum Press, pp.

203-254.

MacDonald, B. A. & M. L. H. 'lhanas. 1982. Growth reduction .in the

soft-shell clam Hya arenaria fran a heavily oiled lagoon .in Oledal:Jucto

Bay, Nov.a scctia. Harine Environmental Research 6:145-156.

Pannella, G. & C. MaCClintock. 1968. Biological am environmental rhytlms ·()

reflected in molluscan shell growth. J. Paleontol. 42:64-80.

•

•

17 pfitzenmeyer, H. T. & K. G. Drobeck. 1964. 'Ihe occurrence of the brackis.'1

water clam, Rangia cuneata in the Potana.c River, Marylarxi. Chesapeake

Science 5(4):209-212.

Ricker, W. E. 1975. carp.rtation an:l inteipretation of biological statistics

of fish pcpllations. Bull. Fish. Res. Board Canada No. 191. 382 p.

Ropes, J. W., D. S. Jones, S. A. Murawski, F. M. serchuk & A. Jerald, Jr.

1984. Documentation of annual growth lines in ocean quahogs, Arctica

islandica Linne. Fishery Bulletin 82(1):1-19.

Taylor, A. c. 1976. Burrowing behavior an:l anaerobiosis in the bivalve

Arctica islandica (L.). J. mar. bioi. Assoc. U.K. 56:95-109.

Taylor, J. D., w. J. Kennedy & A. Hall. 1969. '!he Shell structure an:l

mineralogy of the Bivalvia: Introduction, Nuculacea-Trigoacea. Bull.

Br. 11us. (llfl_t. Hist.) Zool., SUppl. 3, 125 W•

Taylor, J. D. , W. J. Kennedy & A. Hall. 1973. '!he shell structure an:l

mineralogy of the Bivalvia: II. I..ucinacea - Clavagellacea. Conclusions.

Bull. Br. 11us. (Nat. Hist.) Zool. 22(9):253-294.

Trutschler, K. & C. Samtleben. 1988. Shell growth of Astarte eiliptica

(Bivalvia) fran Kiel Bay (Western Baltic sea). 11ar. Ecol. Prog. Ser.

42:155-162.

Wada, K. 1972. Nucleation an:l growth of aragonite crystals in the nacre of

sane bivalve molluscs. Biomineralisation 6:141-159.

Walford, L. A. 1946. A new grapuc method of describing the growth of

animals. Bioi. Bull. 90(2):141-147.

Wolfe, D. A. & E. N. Petteway. 1968. Grc:Mth of Rangia cuneata Gray.

Chesapeake Science 9(2):99-102.

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• ··~

Table 1. Mean an::l rarge in shell ler¢11 (mm) of sprin;J an::l fall recnrlts

of Rarpia cuneata at annuli (winter prismatic barDs) 1-6.

18

N = rnnnber of eadl annulus identified. Sprin;J an::l fall recntits

were defined as those with shell lenjths greater or less than 16

mm, respectively, at the first annulus (see Figure 4).

ANNUI1JS SPRING

N

1 '1. 20.4 55

2 38.2 41

3 51.8 10

4 55.8 8

5

RANGE

16.0-25.0 10.6

30.0-47.3 32.6

46.3-58.5 47.2

49.6-61.0 52.4

54.7

FAIL

N

112

107

88

69

9

6.Q-15.7

21.9-41.0

35.9-54.9

41.0-61.9

44.7-58.0

•

•

Table 2. calall.ated parameters of von Bertalanffy growth equations arrl

calall.ated shell lergths (SL; nun) at aqe (years) for sprin;J am

fall recruits of Bangia cuneata. 11x, = asynptctic shell lenfth;

19

K = growth constant; t 0 = hypothetical aqe at which clam had zero

lenJtb.

SPJIDJG ~

Jix,= 66.2 60.6

K= 0.519 0.604

to= 0.273 0.189

~

~ SL

0.5 10.4

1.0 20.8

1.5 33.1

2.0 39.2

2.5 45.6

3.0 50.1

3.5 52.4

4.0 56.6

4.5 56.1

5.0 60.5

5.5 58.1

·0

•

•

20

FIGURE ux;ENOO

Figure 1. Scannir¥;J electron mi~ of the radial fract'rre {A, c & E)

am inner surfaces {B, D & F) of the cuter crossed lamellar

shell layer of Rarpia o.meata collectej on 18 March (A & B; p -

prismatic ban:l ale>n:J the .inner shell surface), 27 May (C & D)

arxi 31 July 1986 (E & F). In C-F, 1 am 2 denote two adjacent

1• lamellae. In the mi~ of fracture surfaces, the inner

shell surface is at the bottan; growth in all mictcgtalils is to

the right. SCale bars = 3 /Jlll·

Figure 2. Scannir¥;J electron mi~ of polished arxi etched radial '\.

sections of the cuter crossed lamellar (CL) shell layer of

Rangia o.meata. '!he inner shell surface is beyon:1 the bottan

arxi growth is to the right in each mier()3tafil. Micr:cgr:a.r;:hs were

taken ~roximately midway between the inner arxi cuter surfaces

in regions of the cuter layer deposited in: (A) spr:in] 1986,

rapid-growth CL microstructure; (B) late summer 1985, slow­

grc:Mth CL microstructure, diagonal lines in both A & B (fran

1JA)er right to lower left) are microgrowt:h increment ba.lrrlaries;

(C) fall 1985, rapid- (uwet" left) an:i slow- (lower right)

grc:Mth CL microstructure separated by a growth cessation mark;

arxi {D) winter 1985-86, prismatic ban:l surrc::mded by regions of

slow-growth CL microstructure. SCale bars = 5 /Jlll·

•

•

•

21

Figure 3. Light micrograp.,s of acetate peel replicas of polished arrl

etdled radial sections of the outer crossed-lamellar (CL) shell

layer of Rarpia cuneata. Shell grcMth is to the right arrl the

outer shell surface is at the top of each section. Regions of

the outer layer are labelled by season of deposition in 1984 arrl

1985. Rapid-growth CL microstructure appears light, while slow­

grcMth CL microstructure appears dark in acetate peels.

Microgrc:Mth increment :t:nlroaries in the outer layer ~ as

thin dark diagonal lines, while winter prismatic barx1s are

thicker am mre distinct. scale bar in A= 500 J,£m: scale is

the same in all three micrograp.,s.

\.

A. 1983 yearclass (YC) specimen collected 3 February 1986. Tile

ventral shell margin fo:r:ns the right side of the mictogta:(il.

B. 1982 YC specimen collected 29 April 1986. 'lhe ventral shell

margin fo:r:ns the right side of the micrograph.

c. 1981 YC specimen collected 26 March 1987. '1he ventral shell

margin is beyorxi the right side of the mict~a:(il.

Figure 4. Percent 1~-frequency at the first annulus (winter prismatic

band) of the 1982 (N = 93) and 1984 (N = 54) year-classes (YC's)

of Rarpia o.meata collected fran November 1985 through March

1987 • . ~

',_..;

•

•

•

22

Figure 5. A. Mean shell lerxfth at each annulus (winter prismatic ban:l) of

spr.irq ani fall r9Cl:Uits of all Bangia cuneata collected.

0!\ta in Table 1.

B. calculated shell len;Jtlls of spr.irq ani fall recruits of

Bangia cuneata aCXX>l:'din;;J to the von Bertalanffy growth equations

described in Table 2. Sprirq ani fall recruits were assigned

ages of 1 ani 0.5 years, respectively, at their first annuli

(winter prisnatic hanjs).

Figure 6. Shell growth (mean ani ran;e) bY members of the 1982 ani 1984

yearclasses (YC's) of Bangia cuneata fran the winter 1985-86

prismatic ban::l to the ventral shell margin (= the date of

collection) • Specimens were collected on ten dates between

January 1986 ani March 1987.

Figure 7. calculated total <lly tissue weight (mean ± 95% confidence

limits) of a 30 mm (shell lergt:h) specilren of Rangia cuneata on

twe1 ve dates between November 1985 ani Ma.rdl 1987. calculated

dl:y tissue weights were obtained fran a series (one for each

collection date) of least-squares linear regression equations of

log-transfonned <lly tissue weight on log-transformed shell

•

•

•

• • r 1984 1 1985 -------------

SPRING SUMMER

. , , 4 ·.( ;{> . _._,;: .V~ '>/d.:; .- · ··ala;;.. l. -~W~~ ..... _.: :-......:-."".; ··

· r

·---~.......1 .. . ~---....-Gs · · Wl'rtt1tr? - - ·

I 1984 WINTER

t B SUMMEH ri\L L SPHING

~~.;:~~,_-,_,_,¥~~$'" ' ·-. "":-.-- ,..- -. ; . . . . - ~ .. ,. .....

~- ~~-.:. : "" ~ .:'+f·•

-' . ("' ~ · :~

.. ~·,_; .• _ ... ,G-t¢i£11J

I 1984 I I 1985

C . SUMMER

~· --~·~- -·

..,. '""-'::: . ..-:,,:. . . ...oP¥':"~co<'....­~~ _.,....,_.,.. ---

SUMMER SPRING

.(

, ·;~tl ~-.

FALL

.-·it'· ·

1985 I

SUMMER FALL

;-t:.

I

~·

\)

1-z w () 0:: w (L

•

18.-----------------------------------~

16-

14-

12-

10-

B..J

6-

4-

2-

c:::J,-1982 YC - 1984 YC

0 I nil~ Ill H II II~ II IIJ nil~ 1111-· I J I 0 5 7 9 11 13 15 17 19 21 23 25

SHELL LENGTH (mm)

•

70

~ 60 - A E --0 -6. E - - l:l. 50 o·- -· ........., - ,,' 6.~ :c ,o/ r- 40 ~

"' z , l:l. w 30 - , _J , , 0·-- ·0 SPRING _J , _J 20 ~ 0 l:l. -6. FALL w :c (f) 10 .. l:l.

0- I I

0 1 2 3 4 5 6 ·'\.

• ANNULUS NUMBER

70

~ 60 ~ B 0 E 0 6. Ll

E 50 ~ 0 Ll .........,

:c Ll r- 40 0

"' z 6. 0 SPRING w 30 -.....1

Ll FALL _J ....J 20 - 0 w :c (f) 10 ~ Ll

0 I

r---. 0 1 2 3 4 5 6 i

AGE (years)

•

•

....-... Ol ............, .._

I ~ w 3: >-0:: 0

•

0.5.-----------~----------------------~

0.4

0.3

0.2

0.1

, ..

D

0 l D

1 1 6 ..&.

0.0 I I I I I I I I 1. I I I I I I I I I I I 0 N 0 J F M A M J J A S 0 N D J F M A M

1986

•

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