- REFERENCE COPY

- Do Not Remove from the Librorv U. S. Fish and Wildlife h i r n

lvorlonol Wetlands Research Cenwr TR EL-$2-4 ~iological Report 82 (11- 31 ) April, 1986 700 Cajun Dome Boulevarrf

I - Latayette, Louisiana 70506

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Gulf of Mexico)

COMMON RANGIA

a Fish and Wildlife Service

Coastal Ecology Group Watenvavs Ex~eriment Station

U.S. Department of the Interior U.S. Army Corps of Engineers

This i s one of t he f i r s t r e p o r t s t o be published in t h e new "Biological Report" s e r i e s . This technica l r epo r t s e r i e s , published by t h e Research and Development branch of t he U.S. Fish and Wi ld l i f e Serv ice , rep laces t he "FWS/OBS1' s e r i e s published from 1976 t o September 1984. The Biolog- i c a l Report s e r i e s i s designed f o r t h e rap id publ ica t ion of r e p o r t s with an app l i ca t ion o r i e n t a t i o n , and i t cont inues the focus of t h e FWS/OBS s e r i e s on resource management i s s u e s and f i s h and wi Id1 i f e needs.

B i o l o g i c a l Report 82(11.31) TR EL-82-4 A p r i l 1985

Species P r o f i l e s : L i f e H i s t o r i e s and Environmental Requirements o f Coastal F i s h e r i e s and I n v e r t e b r a t e s (Gu l f o f Mexico)

COMMON RANG I A

Mark W. LaSa l l e and

Armando A. de l a Cruz Department o f B i o l o g i c a l Sciences

P.O. Drawer GY M i s s i s s i p p i S t a t e U n i v e r s i t y M i s s i s s i p p i S ta te , MS 39762

P r o j e c t O f f i c e r John Parsons

Na t i ona l Coasta l Ecosystems Team U.S. F i s h and W i l d l i f e Se rv i ce

1010 Gause Boulevard S l i d e l l , LA 70458

Performed f o r

Coasta l Ecology Group Waterways Experiment S t a t i o n U.S. Army Corps o f Engineers

Vicksburg, MS 39180

and

Na t i ona l Coasta l Ecosystems Team D i v i s i o n o f B i o l o g i c a l Serv ices

Research and Development F i s h and W i l d l i f e Serv ice

U.S. Department o f t h e I n t e r i o r Washington, DC 20240

Th i s s e r i e s shou ld be r e f e renced as f o l l o w s :

U.S. F i s h and W i l d l i f e Serv ice . 1983-19 . Species p r o f i l e s : l i f e h i s t o r i e s and env i ronmenta l r e q u i rements o f c o a s t s f i s h e s and i n v e r t e b r a t e s . U. S. F i s h W i l d l . Serv. B i o l . Rep. 82(11). U.S. Army Corps o f Engineers, TR EL-82-4.

T h i s p r o f i l e shou ld be c i t e d as f o l l o w s :

LaSa l le , M.W., and A.A . de l a Cruz. 1985. Species p r o f i l e s : l i f e h i s t o r i e s and env i ronmenta l r e q u i rements o f c o a s t a l f i s h e s and i n v e r t e b r a t e s (Gul f o f Mexico) - - common rang ia . U.S. F i s h W i l d l . Serv. B i o l . Rep. 82(11.31). U.S. Army Corps o f Engineers, TR EL-82-4. 16 pp. e

PREFACE

Th is spec ies p r o f i l e i s one o f a s e r i e s on coas ta l a q u a t i c organisms, p r i n c i p a l l y f i s h , o f s p o r t , commercial , o r e c o l o g i c a l importance. The p r o f i l es a r e designed t o p rov i de coas ta l managers, eng ineers , and b i o l o g i s t s w i t h a b r i e f comprehensive sketch o f t h e b i 01 o g i c a l c h a r a c t e r i s t i c s and env i ronmenta l r e q u i r e - ments o f t h e spec ies and t o d e s c r i b e how popu la t i ons o f t h e spec ies may be expected t o r e a c t t o env i ronmenta l changes caused by coas ta l development. Each p r o f i l e has s e c t i o n s on taxonomy, 1 i f e h i s t o r y , e c o l o g i c a l r o l e , env i ronmenta l requ i rements , and economic importance, i f appl i c a b l e. A t h r e e - r i n g b i n d e r i s used f o r t h i s s e r i e s so t h a t new p r o f il es can be added as t hey a re prepared. Th i s p r o j e c t i s j o i n t l y planned and f inanced by t h e U.S. A n y Corps o f Engineers and t h e U.S. F i s h and W i l d l i f e Serv ice.

Suggest ions o r ques t i ons r e g a r d i n g t h i s r e p o r t shou ld be d i r e c t e d t o one o f t h e f o l 1 owing addresses.

I n f o r m a t i o n T rans fe r Spec ia l i s t Na t i ona l Coastal Ecosys tems Team U.S. F i s h and W i l d l i f e Se rv i ce NASA-Sl i d e l 1 Computer Compl ex 1010 Gause Boulevard S l i d e l 1 , LA 70458

U.S. Army Engineer Waterways Experiment S t a t i o n A t t e n t i o n : WESER-C Pos t O f f i c e Box 631 Vicksburg, MS 39180

CONVERSION TABLE

Me t r i c t o U.S . Customary

Mu1 t i p l y & To Obta in

m i l 1 ime te rs (m) cent imeters (an) meters (m) k i 1 ometers ( km)

2 square meters (m ) 10.76 square k i 1 m e t e r s ( km2) 0.3861 hec ta res (ha ) 2.471

l i t e r s ( 1 ) cub i c meters (m3) cub i c meters

inches inches f e e t m i 1 es

square f e e t square m i l es acres

gal 1 ons cub i c f e e t acre- f e e t

m i l 1 igrams (mg) 0.00003527 ounces grams ( g ) 0.03527 ounces k i l ograms ( k g ) 2.205 pounds m e t r i c tons ( t ) 2205.0 pounds m e t r i c tons 1.102 s h o r t tons k i 1 ocal o r i e s ( kca l ) 3.968 B r i t i s h thermal u n i t s

Cel s i u s degrees 1 . 8 ( " ~ ) + 32 Fahrenhei t degrees

U.S. Customary t o Me t r i c

inches 25.40 inches 2.54 f e e t ( f t ) 0.3048 fathoms 1.829 m i l e s ( m i ) 1.609 n a u t i c a l m i l es ( m i ) 1.852

square f e e t ( f t 2 ) ac res 2 square m i l e s (mi )

ga l 1 ons ( g a l ) cub i c f e e t ( f t 3 ) acre- f e e t

m i l 1 imeters cen t imeters meters meters k i l ometers k i 1 ometers

square meters hectares square k i l ometers

3.785 1 i t e r s 0.02831 c u b i c meters

1233.0 cubic meters

ounces (02) 28.35 pounds ( I b ) 0.4536 s h o r t tons ( t o n ) 0.9072 B r i t i s h thermal u n i t s ( B tu ) 0.2520

grams k i 1 og rams m e t r i c tons k i 1 ocal o r i es

Fahrenhei t degrees 0.5556("F - 32) Ce ls ius degrees

CONTENTS

Page

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii CONVERSION FACTORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v i

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NOMENCLATURE/TAXONOMY/RANGE 1 MORPHOLOGY/ IDENTIFICATION AIDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 REASONS FOR INCLUSION I N SERIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 LIFE HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Spawning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Larvae and Pos t l a r vae 4

A d u l t A c t i v i t y and Feeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L i f e Span 4

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GROWTH CHARACTERISTICS 5 Growth Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S i ze 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . THE FISHERY 6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ECOLOGICAL ROLE 7 Troph ic Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Preda to rs and P a r a s i t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Compet i tors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 S p a t i a l D i s t r i b u t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Dens i t y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

ENVIRONMENTAL REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 S a l i n i t y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Temperature and S a l i n i t y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Subs t r a t e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 E f f e c t s o f P o l l u t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0

LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3

ACKNOWLEDGMENTS

We thank Dr. Courtney T. Hackney, U n i v e r s i t y o f No r t h Ca ro l i na a t Wi l tn ington and Dr. H. D ickson Hoese, U n i v e r s i t y o f Southwestern Lou is iana , f o r t h e i r c r i t i c a l rev iews o f t h e manuscr ip t ; T. Dale Bishop and D a r r y l R. C l a r k f o r i n f o r m a t i o n and h e l p w i t h t h e l i t e r a t u r e search; Mark F. Godcharles, Jake M. Va l en t i ne , and personnel o f t h e Alabama S ta te Docks Department and t h e U. S. Army Corps o f Engineers, Mob i l e D i s t r i c t , f o r p r o v i d i n g comments and unpub l i shed r e p o r t s ; Jeanne J. H a r t l e y f o r he r i l l u s t r a t i o n o f r ang ia ; and D r . Rober t J. Muncy, B e t t y Muncy, and Cindy M i l 1s f o r h e l p i n t h e p r e p a r a t i o n o f t h e manuscr ip t .

F igu re 1. Common rang ia .

COMMON R A N G I A

&

S c i e n t i f i c name . . . . . . . . . . . . . . . . . Rangia cuneata (Gray) (F igure 1)

Pre fe r red common name ........... Common r a n g i a (Andrews 1971; Fotheringham and Brunenmeister 1975)

Other common names . ........... Brack ish water clam, Lou is iana road clam

Class . . ........... .............Molluscs Order. . . . . . . . . . . . . . . . . Eulamell i b r a n c h i a Fami ly . . . . . . . . . . . . . . . . . . . . . . . . Mactr idae

P o s t e r i o r

per ios t racum s inus l i n e

Geographic range: The common rang ia i s found a lonq t h e Gul f o f Mexico coas t (F igure 2 ) - f rom nor thwest F l o r i d a t o Laguna de Terminos, Campeche, Mexico ( D a l l 1894; Andrews 1971; Ruiz 1975), and a long t h e A t l a n t i c coast as f a r n o r t h as Maryland ( P f i tzenmeyer and Drobeck 1964; Gal lagher and Wel ls 1969; Hopkins and Andrews 1970) and

New Jersey (Woodburn 1962). Before 1956, l i v i n g common r a n g i a had n o t been c o l l e c t e d a long t h e A t l a n t i c coast (We1 1 s 1961) p robab ly because e a r l i e r sampling i n b rack i sh water areas had been inadequate. Common r a n g i a i n h a b i t low s a l i n i t y ( 0 t o 18 p p t ) e s t u a r i n e h a b i t a t s (Parker 1966; Christmas 1973; Hopkins e t a l . 1973; Swingle and Bland 1974).

Geol og i ca l l y , t h e common rang i a has been found i n Pl iocene depos i ts i n t he Carol i nas and F l o r i d a and i n P le is tocene depos i ts i n Chesapeake Bay and t h e Potomac R iver , t h e Caro- l i n a s , F l o r i d a , t h e e n t i r e n o r t h coast o f t h e G u l f o f Mexico (F igure 2), and t h e n o r t h coast o f South America (Conrad 1840; D a l l 1894; Maury 1920; Richards 1939).

MORPHOLOGY1 IDENTIFICATION A1 DS

The f o l l o w i n g d e s c r i p t i o n o f common r a n g i a i s taken f rom Abbot t (1954) and Andrews (1971, 1981). A d u l t s range f rom 2.5 t o 6.0 cm i n l eng th . The va lves are o b l i q u e l y ovate, t h i c k , and heavy (F i gu re 1 ) . The e x t e r i o r of t h e s h e l l i s covered w i t h a s t rong , r a t h e r smooth per ios t racum t h a t ranges f rom l i g h t brown t o g r a y i s h brown t o b lack . The umbones are prominent and a re near t h e a n t e r i o r end. The s h e l l i n t e r i o r i s g l o s s y w h i t e w i t h a b lue-g ray t i n g e . The p a l l i a l s i nus i s smal l b u t d i s t i n c t . The p o s t e r i o r l a t e r a l t o o t h i s long (F i gu re 1 ) . D a l l (1894) ment ions t h a t most o f t h e v a r i a b i l i t y i n fo rm i s r e l a t e d t o t h e d i f f e r e n c e s i n t h e h e i g h t o f t h e umbones and t h e shape o f t h e p o s t e r i o r marg in o f t h e she1 1. Rangi a cuneata var. nasutus ( D a l l 1 8 9 4 ) s b e T i e v e d t o 7 Z - T r o s t r a t e fo rm o f R . cuneata (Abbot t * 1954) and may b c o i i T ' E 5 w i t h a c l o s e l y r e 1 a ted species, t h e brown r a n g i a (Rangia f i e x u o s a [Conrad]). The b r o w n r a n q i a i s 2 . 5 t o 4.0 cm lona and resembles an e longa te comma;; rang ia ; however, brown r a n g i a can be e a s i l y separated f rom common r a n g i a by t h e s h o r t p o s t e r i o r l a t e r a l t o o t h and t h e nondi s t i n c t p a l 1 i a1 s inus. Brown r a n g i a i s found from Lou is iana t o Texas and Vera Cruz, Mexico (Andrews 1971), b u t i s much l e s s common than t h e common r a n g i a.

REASOIVS FOR IIVCLUSION I N SERIES

The common r a n g i a i s an impor tan t component o f es tua r i ne ecosystems (Parker 1959; Odum 1967; Odum and Copeland 1969; Copeland e t a l . 1974) account ing , f o r example, f o r n e a r l y 95% o f t h e b e n t h i c biomass i n t h e James R i ve r Estuary, V i r g i n i a (Cai n 1975). I n low s a l i n i t y e s t u a r i n e areas common r a n g i a f u n c t i o n s as a l i n k between p r i - mary producers and secondary consumers. As a non -se lec t i ve f i l t e r feeder , r a n g i a t rans fo rms l a r g e q u a n t i t i e s o f * p l a n t d e t r i t u s and phy top lank ton i n t o clam biomass (Darnel 1 1958; Olsen 1972,

1973, 1976a; Hoese 1973). I n t u rn , t h i s biomass i s consumed by f i s h e s , crustaceans, and ducks (Su t t kus e t a l . 1954; Darnel1 1958; Gunter and S h e l l 1958; Harmon 1962; Nor th C a r o l i n a Bureau o f Spor t F i s h e r i e s and W i l d l i f e 1965; O'Heeron 1966; Cain 1972; Tarver and Dugas 1973). The s h e l l s p rov i de ha rd subs t ra te f o r ep i f auna l at tachment (Hoese 1973).

The common r a n g i a was a food i t e m o f p r e h i s t o r i c I n d i a n s ( M c I n t i r e 1958) anu it i s s t i l l o c c a s i o n a l l y canned and eaten i n New Jersey, Texas, Nor th Caro l ina, and Mexico ( S i n g l e y 1893; Woodburn 1962; Wass and Haven 1970; U. S. Department o f Commerce 1971). Economical ly, common r a n g i a i s more impor tan t as a source o f s h e l l s f o r road b u i l d i n g and i n t h e manufacture o f many i n d u s t r i a1 p roduc ts (Tarver and Dugas 1973; Swingle and Bland 1974; Arndt 1976). Much o f t h i s s h e l l m a t e r i a l i s dredged f rom b u r i e d depos i t s i n es tua r i es .

LIFE HISTORY

The r e p r o d u c t i v e c y c l e and envi ronmenta l c o n d i t i o n s necessary f o r spawning are w e l l known f o r common rang ia . The r e p r o d u c t i v e c y c l e was s tud ied i n Lou i s i ana b y Fa i rbanks (1963), i n V i r g i n i a by Cain (1975), i n F l o r i d a by Olsen (1976b), and i n Campeche, Mexico by Rogers and Garcia-Cubas (1981). Most r a n g i a spawned f rom March t o May and f rom l a t e summer t o November i n Lou i s i ana and f rom February t o June and September t o November i n Mexico. I n bo th areas, spawning may be cont inuous.

I n V i r g i n i a , gametogenesis began i n e a r l y A p r i l and con t inued th roughout t h e summer; gametes were r i p e f rom May through November. Gametogenesis was i n i t i a t e d when water temperature r ose t o 15"C, and spawning was i n i t i a t e d by a r a p i d inc rease o r decrease i n s a l i n i t y (Cain 1975). I n upstream areas o f t h e James R iver ,

el6ue~ 40 (uw op qnoqe) qq6ual ueau aql saqe auo 41 -pau~~~uo3 uaaq qou seq e ~6ue~ uouuo3 aqq 40 ueds a4~ 1 a41

'pas013 A~y3lnb aJe sanlen aqq uaqM uoqdls quelequl aqq q6no~qq 'A~lh~3 alqueu a 04 sa3ajopnasd sapnJqxa Leulue aql '(~~6'1 uas 10) ~1116 a47 Jaho squa~~n3 AJP! 113 pue suolqeln3LqJe d~ed ~1.~6 Aq pal lo~quo3 s~ el6ue~ uouuo3 40 6u~paaj

.saqeJqsqns 40 a~~oq3 e uah~6 uaqM uaha pol~ad qquou-p e Jaho el~enbe ul ahou qou plp sue13 qeqq paq~oda~ (~~6'1) uaslo 'quauLpas aqq uc quauahou ~e3lq~ah 40 A~uo alqede3 aJe et6ue~ qeq3 ~aqsabbns ('186'1) 'Le 7a eJoy LS -el~enbe ul sue~3 40 quauahou a1qq.L 1 PaAJaSqO (€961) SyUPqJ -6~ [qqas Jaqje alqqlL ahou et6ue~ uouuo3

.quaquo3 3~ue6~o ul 46~4 saqeJqs -qns pa~~aja~d pue 6ulqqas JOJ aqeJqs -qns 6ulq3a~as 40 alqede3 aJaM aenJel le41 Pa~JodaJ (€961) SyueqJlej '(5L6'1 ule3) qqoq JO ~014 MO~ 6ulJnp 6u~uu~~s Aq JO 'apLq 6u~uo3u~ ue ul JaqeM uoqqoq aul les aJou aqq ul seaJe uea~qsdn oq paq~odsue~q aq Leu Aaq1 -u leq~a3un s as~adslp el6ue~ aLluahn[ aqq MOH

'Auo~o3 plo~pAq e oq paq3eqqe (6uol luu 1 >) sue13 ~leus LeJahas pahJasqo (~~6'1) asaoH a1 l4M ud 5LE se 1 Leus se salluahnf paq3allo3 (€96'1) syueqJlej 'eue 1s !no1 'u le~q~eq3quod aye1 UI -Jauunsplu u l pa~~n33o pol~ad Gul lqqas puo3as w '(5~6~ ule3) ud OOE pa6eJahP pue 6uol ud 005 oq OEZ aJaM s~euiue aqq uaqM q~ew pue ~aquaqdas uaaMqaq a3e~d yo01 'P~U~~JL/( 'Jah!a sauep aqq ul aehJeL 40 6ul ~qqas qsow

'(596'1 Aalue43) SA~P L ~aq4e ue6aq s~soqd~oweqa~ .ud 081 03 SLI qe s 11 16 u le37e pue 'tun la^ aqq aso 1 'alqqas 03 ue6aq s~a6~ [ahlpad .ud SLl 03 09'1 (pasoqd~oweqau) sJa6~~ahlpad PUP furl ~LI 03 01'1 aen-lel paMoqun Iud OET 03 SL'O aeh-lel pa6ulq-qq6le~qs

:SMO[ 104 se aJaM sa6eqs a4L 1 3uaJa44LP 40 416ual all1 'uol3 -ez!~tq~aj Jaqje q pz UL~~LM pa~eadde aehJe 1 pa laqs qeqq paq~oda~ Aalueq3 'elutb~~~ UI -(~aqaumlp ueau U!

ud €6) 4 E'PE qe ~a6llah e pue 'q E-gz qe aJoqdoq30J$ 3~6elad e 'uocqez~~ Lq~aj Jaqje (4) sJnoq 3.8 padolahap e Lnlse Lq Pale ! L l3 .ud 69 lnoqe seM s66a 40 Jalaurelp a6e~ahe aqq qeq7 paq~oda~ syueqJlej '(~961) Ka ~ueq3 Kq elut6JlA ul Pup (€961) SYJeqJlej Kq euekslnoi ul palpnqs aJaM e ~6ue~ uowuro3 40 quaudolahap 40 sa6eqs Kl~ea aql

.e k6ue~ uouwo3 uo alqellehe aJe eqep Kqlpun3aj ON

aJaM speuo6 qeqq paq~oda~ (1~6'1) ule3 'elu~6~!/( '~a~la sauep aqq UI .s~eaA E oq z ul qq6ual unuiulu q3ea~ p~no3

e 7e41 PaJJa4ul (€96'1) SyUeqJlej 'squaua~3u~ 43~0~6 Lenuue uo eqep uo~j '(€961 syueq~kej) uu pz SPM 'eue~s~no~ 'U ~PJJJP~~JUO~ ay el Ll ! sq Lnpe aJnqeu 40 qq6ua~ unu!ulu aql '(99~6'1 uasl0) PPlJolj u! X'Z Pup ('1861 sWn3 -e~xe~) pue s~a6oa) o~lxaw u! a-0 aq 02 paq~oda~ SPM UP13 Sly3 Ul ~sl~lp0Jqd -eu.iaq 40 az1uapl3ul aql '(If61 ule3) elul6~~/( ul saleu paJaqunuqn0 saLeua4 qnq '(1861 seqn3-el3~e~) pue s~a6oa) o3lxaW pue (€961 syueq~lej) euelslnoi Ul I:I JPaU aq 03 pa3~OdaJ aJaM SOLqPJ xas 'JaleM aqq olu! K~lsa~~p saqaum6 asealaJ P~~UPJ uouuuo3 '6uku~eds UI

' (99L6'1 uas 10) 6u lu~eds 6u ~~a66l~q 40 papad -sns .a.ia~- sasea~3ul Aqlu~ ~es pue aJnq -e~adual -~aquaqda~ ul payead 6uku~eds fJaq~ah0~ q6no~qq A~np uOJ4 paq~oda~ aJaM 6uiu~eds pue saqaueb adl~ 'epl~olj UI ' Lej ul qdd 5 qe payead 6ulu~eds -indqno JaqenqsaJJ pasea~3u 43~~ paqe -13osse qdd oq 01 qnoqe 40 aseaJ3ap AiluLLes e pa~lnba~ Aaqq seaJe ueaJ3s -UMOP U! qnq 'qndqno ~aqe~qsa~4 pa3npa~ 43~~ pa~el3osse qdd s qnoqe 40 asea~3ul Kl~u~~es e paJknbaJ sum13 'elul6.i.~~

c o l l e c t e d i n Lou i s i ana (Tab le I ) , t o es t ima tes o f growth r a t e (Fa i rbanks 1963; Wolfe and Petteway 1968), t h e average l i f e span i s about 4 t o 5 years. A clam of t h e maximum expected l e n g t h of 75 mm, r e p o r t e d by Wolfe and Petteway (1968) i n Chesapeake Bay, would be 10 years o l d . Hopkins e t a l . (1973) es t ima ted a maximum l i f e span o f 15 years.

GROWTH CHARACTERISTICS

Growth Rate

Annual growth increments o f common r a n g i a i n t h e Gu l f o f Mexico a re r e p o r t e d t o v a r y from 0 t o 20 mm (Fa i rbanks 1963; Gooch 1971; Tarver and Dugas 1973). Annual growth increments, es t ima ted f o r t h e f i r s t 3 years o f l i f e f o r two p o p u l a t i o n s i n Lake P o n t c h a r t r a i n , Lou is iana , were 15 t o 20 rn

mm, 5 t o 9 m, and 4 t o 5 mm, r e s p e c t i v e l y (Fa i rbanks 1963). From mean h e i g h t d a t a f o r clams c o l l e c t e d i n Lake Pon t cha r t r a i n , Tarver and Dugas (1973) r e p o r t e d as much as 7.2 m growth i n a 2-month pe r i od . Th i s r a p i d growth appeared t o be r e l a t e d t o warm temperatures. Annual growth r a t e s have been r e p o r t e d t o range f r om 0 t o 9.7 mm f o r V e r m i l i o n Bay, Lou i s i ana (Gooch 1971) and t o be 3 mm i n T r i n i t y Bay, Texas (Bedi nger 1974). Wolfe and Petteway (1968) c a l c u l a ted t h e f o l l ow ing von B e r t a l a n f f y growth cu rve f o r a common r a n g i a p o p u l a t i o n i n t h e T r e n t R i v e r h Ca ro l i na : L = 75.62 (1-0.995 e -0.BP65t) The l a r g e s t p r e d i c t e d l e n g t h o f 75.6 mm would r ep resen t 10 yea rs o f growth.

S i ze - Maximum l e n g t h r e p o r t e d was 94 mm

f o r a common r a n g i a f rom Grand Gos i e r I s l a n d , L o u i s i a n a (H.D. Hoese, Univ .

Table 1. Range o f l eng ths (mm) o r h e i g h t s (mm) o f common r a n g i a examined i n f ou r areas o f Lou is iana .

Area Length He igh t References

Lake Pon t cha r t r a i n , LA 38-42 ( a d u l t s ) --- Fa i rbanks

--- (1963) 1-8 ( j u v e n i 1 es)

--- 28 Tarver (1972)

28-44 Tarver & Dugas (1973)

Lake Maurepas, LA --- 26 Tarver (1972)

25-27 Tarver & Dugas (1973)

Ve rm i l i on Bay, LA 31-61 .-- Gooch (1971)

Sabine Lake - * Atcha fa l aya Bay, LA 28-57 --- Hoese (1973)

Southwestern La. ; pers . comm. ) . Mean s i z e s ( l eng th , a n t e r i o r t o p o s t e r i o r ; he igh t , umbo t o v e n t r a l marg in) r epo r t ed f rom o t h e r Lou i s i ana e s t u a r i e s are shown i n Tab le 1. Parker (1960) and Hoese (1973) r epo r t ed t h a t t h e l a r g e s t clams we.re found i n t h e lower s a l i n i t y areas o f e s t u a r i e s , whereas, Tarver and Dugas (1973) found t h a t clam s i z e inc reased w i t h s a l i n i t y . I n V i r g i n i a , Cain (1972) noted t h a t clams l i v i n g i n sand were t y p i c a l l y l a r g e r than those l i v i n g i n mud.

THE FISHERY

The foremost commercial va lue of common r a n g i a i s i n t h e use o f f o s s i l s h e l l s f o r road b u i l d i n g m a t e r i a l , o y s t e r c u l t c h , and as a source of ca lc ium carbonate f o r t h e manufacture o f g lass, chemicals, ch icken and c a t t l e feed, wal lboard, and a g r i c u l t u r a l 1 ime (Tarver and Dugas 1973; Swingle and Bland 1974; Arndt 1976). Clam s h e l l s a re harves ted by l a r g e commercial hydrau l i c dredges. By f a r t h e l a r g e s t concen t ra t i ons o f l i v i n g clams are along t h e Lou i s i ana coast. The minimum s tand ing c rop o f clams es t imated t o be between t h e A tcha fa laya R i v e r and Sabine Lake, Louis iana, was between 24 b i l l i o n and 48 b i l l i o n clams (Hoese 1973). Because o f t h e r e l a t i v e l y s low growth r a t e o f rang ia , Hoese (1973) suggested t h a t no more than 5% o f t h e l i v i n g clam p o p u l a t i o n should be harves ted annual l y i f c u r r e n t p roduc t i on o f f o s s i l s h e l l s i s t o be mai n t a i ned; however, a t an annual r e c r u i t m e n t o f 5% (Fai rbanks 1963) t he es t imated s h e l l depos i t s i n Lake P o n t c h a r t r a i n would be n e a r l y exhausted i n 35 years ; a t 3% Tarver and Dugas (1973) es t imated d e p l e t i o n i n 18 years.

The po ten t i a1 sources o f common r a n g i a s h e l l along t h e g u l f coast have been 1 i s t e d by Arndt (1976). I n Texas, s h e l l occurs i n t h e upper reaches o f San Anton io Bay, Nueces and Lavaca Bays, Galveston Bay, T r i n i t y Bay, and Sabine Lake. I n Louis iana, depos i t s

extend f rom P o i n t au Fer (A t cha fa l aya Bay) west t o t h e Texas border , Calcas ieu and Sabine Lakes, and Lake Pon tcha r t r a i n . I n M i s s i s s i p p i , clams l i v e i n t h e Pear l R i v e r Es tuary and M i s s i s s i p p i Sound; i n Alabama, i n upper Mob i l e Bay; and i n F l o r i d a i n Choctawhatchee Bay, Tampa Bay, t h e Caloosahatch ie R i v e r (Arnd t 1976), and t h e upper reaches o f C h a r l o t t e Harbor (Woodburn 1962).

The Lou is iana W i l d l i f e and F i s h e r i e s Commission (1968) es t ima ted a s ta tew ide p roduc t i on o f about 5 m i l l i o n c u b i c yards o f clam s h e l l i n 1968 compared w i t h 300,000 c u b i c yards annua l l y i n t h e mid-1930's. The maximum annual harves t o f s h e l l i n t h e g u l f S ta tes was 21.2 m i l l i o n t ons i n 1967 compared w i t h 468,000 t ons i n 1912 (Arnd t 1976). O f t h e m a t e r i a l dredged i n 1967, an es t imated 12.2 m i l l i o n tons was used i n c o n s t r u c t i o n and t h e remainder f o r road base, aspha l t f i l l , p o u l t r y g r i t , c a t t l e roughage, f i l t e r m a t e r i a l , and w h i t i n g (p igment) .

Na t i ve Americans used common r a n g i a as food, as evidenced from s h e l l depos i t s i n I n d i a n middens along t h e gu l f coast (S ing ley 1893; McInt i r e 1958). The canning of r a n g i a i n Texas under t h e name o f " l i t t l e neck clams" b y t h e Givens Oyster Company was r e p o r t e d by S ing ley (1893). Rangi a were a l so canned a t Cape May, New Jersey (Woodburn 1962) and i n No r th C a r o l i n a (U.S. Department o f Commerce 1971). Rangia have been c o l l e c t e d and consumed f r om t h e Potomac Creek o f t h e Potomac R iver , Mary1 and ( P f i tzenmeyer and Drobeck 1964), t o Mexico where Wass and Haven (1970) r epo r t ed t h a t t h i s clam was served w i t h r i c e as " P a e l l a a va lenc ianna" i n r es tau ran t s . The p o t e n t i a l use o f t h i s clam as food, however, i s seve re l y l i m i t e d by con tamina t ion o f 1 arge p o t e n t i a l sources b y p o l l u t i o n (Chr is tmas 1973; Swingle and Bland 1974). Rangia a re a l s o used as b a i t f o r b l u e crabs (Godcharl es and Jaap 1973).

ECCILOGICAL ROLE

Trophic Level

Common r a n g i a serve t o l i n k p r ima ry producers and secondary consumers i n e s t u a r i n e areas. Rangia are non -se lec t i ve f i l t e r feeders (Darnel 1 1958; Olsen 1976a) i n g e s t i n g 1 arge q u a n t i t i e s o f d e t r i t u s and phytoplankton. Darnel1 (1958) r e p o r t e d t h a t gu t con ten ts con ta ined 70% u n i d e n t i f i a b l e d e t r i t u s , 10% sand, 17% a1 g ae ( p o s s i b l y Anabaena o r M i c r o c y s t i s ) as w e l l as t r a c e s o f diatoms, f o ram in i f e ra , and vascu la r p l ant ma te r i a1 . Olsen (1976a) r e p o r t e d 48 species o f phy top lank ton f rom stomach con ten ts o f common r a n g i a, a l though a l a r g e p o r t i o n o f t h e m a t e r i a l i nges ted was d e t r i t u s (46 t o 81%, depending on t i d a l c o n d i t i o n s ) .

m Predato rs and Pa ras i t es

Common r a n g i a are preyed upon by f i s h , crustaceans, mol lusks, and ducks (Table 2; Su t tkus e t a l . 1954; Darnel1 1958; Gunter and S h e l l 1958; Harmon 1962; Nor th C a r o l i n a Bureau o f Spor t F i s h e r i e s and W i l d l i f e 1965; OIHeeron 1966; Cain 1972; Tarver and Dugas 1973). I n add i t i on , moon s h e l l s n a i l s ( P o l i n i c e s spp.) may be p reda to r s as suggested by d r i l l ho les i n r a n g i a she1 1s (Hoese 1973). Common r a n g i a are abundant i n t h e d i e t s o f b l u e c a t f i s h , f reshwater drum, spot, b l ack drum, r i v e r shrimp, and b l u e c rab i n Lake Pon tcha r t r a i n , Lou i s i ana (Darnel1 1958, 1961). The sma l le r r a n g i a are sub jec ted t o t h e g r e a t e s t p r e d a t i o n pressure. Clams as l a r g e as 40 mm ( l e n g t h o r h e i g h t ) , however, are eaten by f i s h e s such as sheepshead and b lack drum (Darnel1 1958; Tarver and Dugas 1973). A p o t e n t i a l group o f p reda to r s n o t mentioned by t h e above au thors a re t h e ctenophores ( e . Mnemioposis) which sometime appear i n tremendous numbers a t c e r t a i n t imes o f t h e yea r * (M. W. LaSal 1 e, pers . observ. ). Cteno- phores can cause mass m o r t a l i t y o f

1 arvae i f c o i n c i d e n t a l w i t h r a n g i a spawning.

The common r a n g i a i s p a r a s i t i z e d by 1 arvae o f f e l l o d i s t o m a t i d trematodes (Fai rbanks 1963). Cerc ar i ae and sporocys ts o f t h i s p a r a s i t e a re found i n t h e gonadal t i s s u e , g i v i n g i t an orange c o l o r a t i o n and e f f e c t i n g c a s t r a t i o n . Only l a r g e clams are i n f e c t e d .

P o t e n t i a1 compe t i t o r s o f common r a n g i a may be reduced b y t h e wide range o f s a l i n i t i e s t o l e r a t e d b y t h i s clam (Odum 1967). Pol ymesoda c a r o l i n i a n a has f eed ing h a b i t s i d e n t i c a l t o those o f r a n g i a (Olsen 1973, 1976a), b u t i s s p a t i a l l y separated f rom rangia; i t i s found p r i m a r i l y i n i n t e r t i d a l areas o r i n smal l numbers i n t h e sha l low nearshore s u b t i d a l areas. I n c o n t r a s t , r a n g i a l i v e l a r g e l y i n t h e s u b t i d a l zone. Other p o t e n t i a l compet i to rs a re appa ren t l y n o t adapted t o f l u c t u a t i n g s a l i n i t i e s .

S p a t i a l D i s t r i b u t i o n

Common r a n g i a a re p r i m a r i l y r e s t r i c t e d t o low s a l i n i t y ( < 19 p p t ) e s t u a r i e s (Maury 1920; P u l l e y 1952; Parker 1955, 1956, 1960; Moore 1961; Parker 1966; Odum 1967; Christmas 1973; Hoese 1973; Hopkins 1970; Hopkins e t a l . 1973; Swingle and Bland 1974). Rangi a have been r e p o r t e d f rom areas as f a r as 25 m i l e s upstream i n d e l t a r i v e r s (Swi ng le and Bland 1974), bu t most p r e f e r s a l i n i t i e s o f 5 t o 15 pp t . Tarver and Dugas (1973) found t h a t concen t ra t i ons o f clams were h i ghes t ad jacen t t o a p o t e n t i a l source o f f r e s h o r s a l t water, which may be r e l a t e d t o t h e need f o r s a l i n i t y shock r e q u i r e d f o r spawning (Cai n 1973). Concent ra t ions o f clams were g r e a t e s t around t h e p e r i p h e r y o f Lake P o n t c h a r t r a i n and Lake Maurepas (Tarver 1972; Dugas e t a l . 1974). D ispers ion of adu l t clams i s commonly clumped

Table 2. Reported p reda to r s o f a d u l t and j u v e n i l e common rang ia .

Species!common name Adu l t s Juveni 1 es References (<5 mm)

Aythya a f f i n i s -- l e s s e r scaup duck Aythya marila-- g r e a t e r scaup duck

=is -- r ing-necked duck A n a s u b r i p e s -- American b l a c k duck Anas p l atyrhynchos -- ma1 1 a rd m r a jamaicensis - - ruddy duck -is sabina - - A t l a n t i c s t i n g r a y Lepisosteus productus -- spo t t ed gar Lepisosteus s p a t u l a -- a l l i g a t o r ga r Le i sos teus osseus -- n o r t h e r n longnose gar h e p m m -- g i z z a r d Shad Anchoa m i t c h i l l i -- southern bav anchovv A r i u s f a i s -- <ea c a t f i s h ~ u ~ u r c a t u s - - b l u e c a t f i s h Ap lod ino tus grunniens -- f reshwater drum Leiostomus xanthurus -- soot . - r -

M ic ro o onias. undulatus -- A t l a n t i c c roaker -1% -- b l a c k drum X - - . . . -. - - . - . . . . - . .~ -. . -.

7 rchosar us robatocephalus -- sheepshead X aqo on r om o ides -- p i n f i s h &I

~ a r a l i c h t h y s l e t hos t i gma -- southern f l ounde r Cvnoscion a renar ius -- sand sea t rou t " Thasmodes bosquianus -- s t r i p e d b lenny Penaeus s e t i t e r u s -- wh i t e shr imo ~- - ~-

Racrobrachium ohione -- r i v e r shr;m~ - a m - - b l u e crab R h i t h r o ~ a n o ~ e u s h a r r i s i i -- mud crab , ~, -~ ~

T h a i s haemastoma -- o~vs te r d r i l l E l X i c e s spp. -- moon s h e l l ( p o s s i b l e )

References: ( 1 ) Su t tkus e t a l . (1954); ( 2 ) Darnel1 (1958); ( 3 ) Gunter and She l l (1958); (4) Harmon (1962); (5) No r th C a r o l i n a Bureau o f Spor t F i s h e r i e s and Wi ld1 i f e (1965); (6) OIHeeron (1966); (7) Cain (1972); (8) Hoese (1973)

whereas j u v e n i l e s may be d i s t r i b u t e d 818/m2 i n Lake Maurepas, L o u i s i an more u n i f o r m l y (Fa i rbanks 1963). (Tarver and Dugas 1973), and 238/m 9

i n Ve rm i l i on Bay, Lou is iana . Average d e n s i t y o f clams f r om sha l low water

Dens i t y areas between t h e A tcha f 1 aya R i ve r and Sabi e Lake was l lll f o r adu l ts , ! The d e n s i t y o f clams v a r i e s 14/m f o r j u v e n i l e clams > 10 mm, and

g r e a t l y ( f o r reasons d iscussed l a t e r ) . 28/m2 f o r j u v e n i l e clams < 10 m The h i ghes t d e n s i t y o f a d u l t clams was (Hoese 1973). D e n s i t i e s as h i gh as c.

129/m2 were r e p o r t e d i n Texas bays (Odum 1967). A mean d e n s i t y o f 250/m2 was r e p o r t e d i n t h e Nueces R iver , Texas (Hopkins and Andrews 1970). I n Lake Pon t cha r t r a i n , Louis iana, mean d e n s i t i e s ranged from 2.7 t o 311T2 f o r l a r g e clams and 1807 t o 18881111 f o r j u v e n i l e s (Fa i rbanks 1963).

ENVIRONMENTAL REQUIREMENTS

A combina t ion o f low s a l i n i t y , h i gh t u r b i d i t y , and a s u b s t r a t e o f sand, mud, and vege ta t i on appears t o be t h e most f avo rab le h a b i t a t f o r t h e common r a n g i a (Tarver 1972). T h i s clam may be one of t h e few f r eshwa te r clams t o become e s t a b l i s h e d i n b r a c k i s h water (Ladd 1951). Conversely, Remane and Schl i e p e r (1971) cons idered comnon r a n g i a as be l ong ing t o a mar ine group t h a t has become adapted t o b r a c k i s h water .

Temper a t u re

Winter k i l l s i n t h e sha l low wate rs o f Chesapeake Bay suggest t h a t common r a n g i a had reached i t s l i m i t o f temperature t o l e r a n c e t h e r e (Gal 1 agher and Wel l s 1969). Cain (1975) r e p o r t e d t h a t water tempera tu re was t h e most impo r t ant f a c t o r s t imul a t i ng gametogenesis. He a l s o s t a t e d t h a t t h e p l a n k t o n i c e x i s t e n c e of l a r v a e i s g r e a t l y extended by low temperature.

Sal i n i t y

Common r a n g i a are concen t ra ted i n areas where s a l i n i t y seldom exceeds 18 p p t (Maury 1920; P u l l e y 1952; Parker 1956, 1960; Mogre 1961; Parker 1966; Odum 1967; Godcharles and Jaap 1973; Hoese 1973; Swingle and Bland 1974). Tarver and Dugas (1973) r e p o r t e d a nega t i ve c o r r e l a t i o n ( r = 0.71) between d e n s i t y of clams and s a l i n i t y and a p o s i t i v e c o r r e l a t i o n ( r = 0.81) between clam h e i g h t and s a l i n i t y ( 0 t o 6 p p t ) . Godcharles and Jaap (1973) found a

g r e a t e r number o f s i z e c l asses and l a r g e r clams a t low s a l i n i t i e s ( 0 t o 2 p p t ) t h a n a t h i ghe r ones i n F l o r i d a and suggested t h a t t h i s range was op t ima l .

Common r a n g i a have developed phys- i o l o g i c a l responses t o t h e f r equen t and sudden s a l i n i t y changes p resen t i n many e s t u a r i e s . Common r a n g i a i s an osmoconformer a t s a l i n i t i e s g r e a t e r t han 10 p p t , and an osmoregulator a t 1 ower s a l i n i t i e s (Bedford and Anderson 1972a,b; O t t o and P ie r ce 1981a,b). A number o f amino a c i d s ( i n c l u d i n g a l a n i n e , g l y c i n e , g l u tamic and a s p a r t i c ) a re concen t ra ted a t h i gh s a l i n i t i e s sugges t ing t h a t an amino a c i d poo l i s used f o r osmoregu la t ion (Simpson e t a l . 1959; A l l e n and Awapara 1960; A l l e n 1961; Anderson and Bed fo rd 1973; Anderson 1975).

Temperature and Sal i n i t y

Cain (1972, 1973, 1974) t e s t e d t h e combined e f f e c t s o f temperature ( 8 t o 32°C) and s a l i n i t y ( 0 t o 20 p p t ) on embryos and l a r v a e o f common rang ia . Embryos f a i l e d t o develop a t 0 p p t s a l i n i t y . The optimum c o n d i t i o n s f o r embryos were temperatures o f 18 t o 2g°C and s a l i n i t i e s o f 6 t o 10 p p t .

Larvae s u r v i v e d a t a1 1 combinat ions of temperature and s a l i n i t y t e s t e d (except a t 0 p p t ) . They t o l e r a t e temperatures o f 8 t o 32°C and s a l i n i t i e s o f 2 t o 20 pp t . Growth o f l a r v a e was bes t a t h i g h s a l i n i t y (10 t o 20 p p t ) and h i g h tempera tu re (20 t o 32°C). S t r a i g h t - h i n g e d 1 arvae were f ound t o be more t o l e r a n t t han embryos t o extremes o f temperature and s a l i n i t y .

Oxygen

Common r a n g i a can w i t hs tand anox ic c o n d i t i o n s as r e p o r t e d b y Chen and Awapara (1969) i n s t u d i e s of g l y c o l y s i s ; however, r a n g i a a re i n t o l e r a n t o f exposure t o a i r (Olsen 1976b).

Subst ra te

Common r a n g i a are found i n a wide range of so f t subs t ra tes i n t h e nor thern Gulf of Mexico. Tenore e t a l . (19681, who s tud ied t h e e f f e c t s o f c lay , s i l t , and sand subs t ra tes on t h e common rang ia , found c l a y and s i l t t o be unfavorable, whereas Cai n (1975) commonly found clams i n s i l t y - c l a y sediments. Parker (1966) found clams on sand, s i l t , and c l a y sediments where these c o n s t i t u e n t s d i d no t exceed 80, 30, and 65%, r e s p e c t i v e l y . Few clams were c o l l e c t e d from hard sand o r c l a y bottoms i n Lou is iana (Tarver 1972) o r i n Alabama (Swingle and Bland 1974). I n Louisiana, t h e numbers o f common r a n g i a were h ighes t i n a m ix tu re o f sand, mud, and vegeta t ion (Tarver 1972), whereas i n A1 abama, dense popu la t ions 1 i v e d i n compacted sandy- c l a y areas (Swingle and Bland 1974). I n F l o r i d a , common rang ia were c o l 1 ec ted from s o f t mud (Godcharl es and Jaap 1973; Woodburn 1962), b u t i n Georgia, clams were found i n mud o r s o f t mud-sand combinat ions (Godwin 1968).

The importance o f o rgan ic mat te r i n t h e sediment t o common r a n g i a i s no t c l ea r . Fai rbanks (1963), who found t h e l a r g e s t d e n s i t i e s o f r ang ia i n h i g h l y o rgan ic sediments i n Lake Pon tcha r t ra i n , Louis iana , suggested t h e 1 arge amounts o f associated b a c t e r i a helped t o a t t r a c t and support clams. High organ ic content i n sediments was a l so f avo rab le f o r r a n g i a i n Vermi 1 i o n Bay, Lou is iana (Gooch 1971). However, no c o r r e l a t i o n e x i s t e d between t h e abundance o f common r a n g i a and t h e percentage o f organic ma t te r i n t h e sediment a t l e v e l s below 10% (Hoese 1973). Few clams were found i n sediments w i t h more than 10% organ ic ma t te r i n Lou is iana (Hoese 1973) and Alabama (Swingle and Bland 1974). M o r t a l i t y o f r a n g i a can r e s u l t f rom s h e l l erosion, which can be acce le ra ted i n h i g h l y aerated sediments i n which carbonic ac ids a re re leased (Tarver and Dugas 1973).

The subs t ra te of some coas ta l waters i s ma in l y s h e l l s which are o f t e n dredged commercial ly. For example, t h e common r a n g i a makes up much of t h e hard subs t ra te o f Lake Pon tcha r t ra in i n Louis iana. The e f f e c t s of s h e l l dredging on t h e subs t ra te and benthos are t o o complex and c o n t r o v e r s i a l t o d iscuss i n t h i s p r o f i l e . See Dugas e t a1. (1974), Tay lo r (1978), S i ko ra e t a l . (1981), and S ikora and S i ko ra (1982).

The h ighes t concent ra t ion of clams along t h e g u l f coast has been associated w i t h shal low water areas l e s s than 6 m deep (Tarver 1972; Hoese 1973; Godcharles and Jaap 1973; Tarver and Dugas 1973; Dugas e t a l . 1974). Tarver and Dugas (1973) observed a general decrease i n d e n s i t y as depth increased from 2.5 t o 4.6 m.

E f f e c t s o f P o l l u t i o n

Common r a n g i a are known t o concentrate chemicals such as kepone. Lunsford (1981) repo r ted t h a t peak kepone l e v e l s i n common r a n g i a du r i ng summer, i n t h e James R ive r Estuary, were r e 1 ated t o increased met abol i sm and feed ing r a t e . The concen t ra t i on o f kepone was 2 t o 4 t imes g rea te r i n r a n g i a than i n t h e water column (Lunsford and Blem 1982). The key f a c t o r s a f f e c t i n g kepone uptake were water temperature, d i sso l ved oxygen concentrat ion, 1 i p i d index of c l am t i ssue , t u r b i d i t y , kepone concen t ra t i on i n t h e water, and t h e d u r a t i o n of exposure (Lunsf o rd and Blem 1982). Kepone i s adsorbed by p a r t i c u l a t e mat ter , which enhances i t s uptake by f i l t e r feeders such as comnon rangia. Uptake o f o i l r e l a t e d products such as benzopyrene, naphthalenes, and var ious aromatic hydrocarbons has a l so been repo r ted (Cox 1974; Nef f e t a l . 1976). A1 1 o f these compounds were accumulated p r i m a r i l y i n t h e v i s c e r a and f a t bodies o f clams under d i r e c t exposure and most were read i l y r e 1 eased when c l ams were

re tu rned t o c lean water. Low l e v e l s of The e f fec ts o f low concent ra t ions of these contaminants, however, were contaminants on common rang ia are no t r e t a i n e d by t h e clams i n each case. known.

LITERATURE CITED

Abbot t , R. T. 1954. American sea- s h e l l s . Van Nostrand, New York. 541 pp.

A l l e n , K. 1961. The e f f e c t o f s a l i n - i t y on t h e amino ac id concentra- t i o n i n Rangia cuneata (Pele- cypoda). B i o l . B u l l . (Woods Hole) 121: 419-424.

A l l en , K . , and J. Awapara. 1960. Metabolism of s u l f u r amino ac ids

118: 173-182.

Anderson, J. W. 1975. The uptake and i n c o r p o r a t i o n o f g l y c i n e by t h e g i 11 s o f Rangia cuneata (Mol l usca: B i v a l v i a ) i n response t o v a r i a - t i o n s i n s a l i n i t y and sodium. Pages 239-258 i n F.J. Vernberg, ed. ~ h y s i o l o g i c a l ecology o f es tua r i ne organisms. U n i v e r s i t y o f South Carol i na Press, Col umbia.

Anderson, J. W . , and W. B. Bedford. 1973. The phys io l og i ca l responses o f t h e es tua r i ne clam, Rangia cuneata (Gray), t o s a l i n i t y . 11. Uptake o f g l yc i ne . B i o l . B u l l . (Woods Hole) 144: 229-247.

Andrews, J. 1971. Sea s h e l l s o f t h e Texas coast. U n i v e r s i t y o f Texas Press, Aus t in . 298 pp.

on g u l f coas t environments. G u l f Pub1 i s h i n g Co. , Houston, Tex.

Bedford, W. B., and J. W. Anderson. 1972a. The p h y s i o l o g i c a l response of t h e es tua r i ne clam, Rangia cuneata (Gray). I . Osmoregul a- t i o n . Phys io l . Zool. 45: 255-260.

Bedford, W. B., and J. W. Anderson. 1972b. Adapt ive mechanisms o f t he es tua r i ne b i v a l v e , Rangia cuneata, t o a sa l i n i t y s t ressed environment. Am. Zool . 12: 721. (Abstr . )

Bedinger, C. A. , J r . 1974. Seasonal changes i n c o n d i t i o n and b iochemical cons i tuen ts o f t h e b rack i sh water clam Rangi a cuneata (Grav). 1831. Ph. D. D i s s e r t a t i o n . ~ e x 2 - . A&M U n i v e r s i t y , Col lege S ta t i on . 179 pp.

Beyers, R. J . , and R. W. Warwick. 1968. The ~ r o d u c t i o n o f carbon d i o x i d e by Rangia cuneata. Cont r ib . Mar. Sc i . 13:45-50.

Cain, T. 0. 1972. The rep roduc t i ve c y c l e and l a r v a l to le rances o f ~ a n ~ i a cuneata i n t h e James R iver , V i r g i n i a . Ph. D. D i s s e r t a t i o n . ~ n i i e r s i t y o f V i r g i n i a , C h a r l o t t e s v i l l e . 250 pp.

Andrews, J. 1981. Texas s h e l l s : a Cain, T. 0. 1973. The combined f i e l d guide. U n i v e r s i t y o f Texas e f f e c t s o f temperature and Press, Aus t in . 175 pp. s a l i n i t y on embryos and l a r vae o f

t h e clam Rangia cuneata. Mar. Arndt , R. H. 1976. The she1 1 dredging B i o l . 21: 1-6.

i n d u s t r y o f t h e g u l f coas t reg ion . Pages 13-48 i n A. Bouma, ed. Cain, T. 0. 1974. Combined e f f e c t s o f She1 1 dredgi n g a n d i t s i n f 1 uence changes i n temperature and

s a l i n i t y on e a r l y stages o f Rangia cuneata. Va. J. Sc i . 25:30-31.

Cain, T. D. 1975. Reproduct ion and rec ru i tmen t o f t h e b rack i sh water clam Rangia cuneata i n t he James R iver , V i r g i n i a . U.S. N a t l . Mar. F ish. Cerv. F ish. B u l l . 73: 412-430.

Chanley, P. 1965. Larva l development o f t h e b rack i sh water m a c t r i d clam, Rangia cuneata. Chesapeake Sci . 6: 209-213.

Chen, C. , and J. Awapara. 1969. E f f e c t s o f oxygen on t h e end- p roduc ts o f g l y c o l y s i s i n Rangia cuneata. Comp. Biochem. Phys io l . 31: 395-401.

Christmas, J . Y. 1973. Cooperat ive G u l f o f Mexico e s t u a r i n e i n v e n t o r y and study. M i s s i s s i p p i G u l f Coast Res. Lab. , Ocean Spr ings.

Conrad, T. A. 1840. On t h e S i l u r i a n system, w i t h a t a b l e o f t h e s t r a t a and c h a r a c t e r i s t i c f o s s i l s : observa t ions on t h e genus Gnatho- don w i t h d e s c r i p t i o n o f a new - species. Am. J . Sc i . 38:92-93.

Copeland, B. J . , K. R. Tenore, and D. B. Horton. 1974. 01 i goha l i n e regime. Pages 315-35 H. T. Odum, B. J. Copeland, and E. A. McMahan, eds. Coastal eco log i ca l systems o f t h e U. S. , Vol . 2. The Conservat ion Foundation, Washing- ton , D.C.

COX, 8. A. 1974. Responses o f t h e marine a1 myra I v e s , (L inn.

crustaceans Mysidopsis - Bowman, Penaeus aztecus and Penaeus s e t i f e r u s t o ~ e t r o l e u m hvdrocarbons.

~ h . D. - ~ i s s e r t a t i o n . Texas A&M U n i v e r s i t y , Col lege S ta t i on . 182 PP.

D a l l , W. H. 1894. Monograph o f t h e genus Gnathodon Gray (Rangia Des- m o u l i n ~ ~ c . U.S. N a t l . Mus. 17: 89-106.

Darnel 1, R. M. 1958. Food h a b i t s o f f i s h e s and 1 a rger i n v e r t e b r a t e s o f Lake Pon tcha r t r a i n, Louis iana, an e s t u a r i n e community. Publ. I n s t . Mar. Sc i . Univ. Tex. 5:353-416.

Darnel 1, R. M. 1961. T roph ic spectrum o f an es tua r i ne community based on s tud ies o f Lake Pon tcha r t r a i n , Louis iana. Ecology 42: 553-568.

Dugas, R. J . , J. W. Tarver , and L. S. Nu twe l l . 1974. The mo l lusk communities o f Lakes Pon tcha r t r a i n and Maurepas , Louis iana. La. W i l d l . F ish. Comm. Tech. B u l l . No. 10. 1 3 p p .

Fai rbanks. L. D. 1963. B iodemoara~h ic s tud ies o f t h e clam Rangia Euneata Gray. Tulane Stud. 2001. 10:3-47.

Fotheringham, N., and S. Brunenmeister. 1975. Common marine i n v e r t e b r a t e s o f t h e nor thwest g u l f coast . G u l f Pub'l i s h i n g Co. , Houston, Tex.

Ga l lagher , J . L., and H. W. Wel ls . 1969. Nor thern range ex tens ion and w i n t e r m o r t a l i t y o f Rangia cuneata. Naut i 1 us 83: 22-25.

Godcharles, M. F., and W. C. Jaap. 1973. Exp lo ra to r y clam survey o f F l o r i d a nearshore and e s t u a r i n e waters w i t h commercial hydraul i c dredging gear. F l a . Dep. Nat. Resour. Mar. Res. Lab. Pro f . Pap. Ser. No. 21. 77 pp.

Godwin, W. F. 1968. The d i s t r i b u t i o n and d e n s i t y o f t he b rack i sh water clam, Rangia cuneata i n t h e Altamaha R iver , Georgia. Ga. F i s h Game Comm., Mar. F ish. Div . Cont r ib . Ser. No. 5 : l -10 .

Gooch, D. M. 1971. A study o f Rangia cuneata Gray, i n Ve rm i l i on Bay, Louis iana. M. S. Thesis. Univer- s i t y o f Southwestern Louis iana, La faye t te . 48 pp.

Gunter, G., and W. E. She l l , J r . 1958. A study o f an es tua r i ne area w i t h

wate r - l eve l c o n t r o l i n t he L o u i s i - ana marsh. Proc. La. Acad. Sc i . 21: 5-34.

Harmon, B. G. 1962. Mo l lusk as food o f l e s s e r scaup a long t h e L o u i s i - ana coast . Trans. N. Am. W i l d l . Conf. 27: 132-138.

Hoese, H. D. 1973. Abundance o f t h e low s a l i n i t y clam, Rangia cuneata i n southwestern Louis iana. Proc. Na t l . S h e l l f i s h . Assoc. 63: 99-106.

Hopkins, S. H. 1970. Studies on t h e b rack i sh water clams o f t h e genus Rangia i n Texas. Proc. N a t l . S h e l l f i s h . Assoc. 60: 5-6. (Abstr . )

Hopkins, S. H., and J. D. Andrews. 1970. R a ~ g i a cuneata on t h e eas t coast : thousand m i l e range ex tens ion o r resurgence? Science 167 : 868-869.

Hopkins, S. H., J. W. Anderson, and K. Horvath. 1973. The b rack i sh water clam Rangia cuneata as i n d i c a t o r o f eco log i ca l e f f e c t s o f sa l i n i t y changes i n coas ta l waters. U.S. Army Engineer Waterways Exp. Stn. , Vicksburg, Miss. Cont rac t Rep. No. DACW39-71-C-0007.

Ladd, H. S. 1951. Brack ish-water and marine assemblages o f t h e Texas coas t w i t h spec ia l re fe rence t o mol lusks. Publ. I n s t . Mar. Sc i . Univ. Texas. 2:12-164.

Lou is iana W i l d l i f e and F i s h e r i e s Com- miss ion. 1968. The h i s t o r y and r e g u l a t i o n o f t h e she1 1 dredging i n d u s t r y i n Louis iana. La. W i l d l . FishComm. 3 2 p p .

Lunsford, C. A. 1981. Kepone d i s t r i - b u t i o n i n t h e water column o f t h e James R iver Estuary - 1976-78. Pes t i c . Moni t . J. 14:119-124.

Lunsford, C.A., and C. R. Blem. 1982. Annual c y c l e o f Kepone res idue and l i p i d con ten t o f t h e es tua r i ne clam, Rangia cuneata. Es tuar ies 5: 121-130.

Maury, C. 3 . 1920. Recent mol lusks o f t h e Gu l f o f Mexico and P le is tocene and P l iocene species from the G u l f States. B u l l . Am. Pa leonto l . 8 : l - 115.

M c I n t i r e , W. G. 1958. P r e h i s t o r i c I n d i a n se t t lements o f t h e changing M i s s i s s i p p i R i ve r De l ta . La. S ta te Univ. Coastal Stud. Ser. 1: 1-128.

Moore, D. R. 1961. The marine and b rack i sh water mol l usca o f t h e s t a t e o f M i s s i s s i p p i . G u l f Res. Rep. 1: l -58.

Ne f f , J. M. , B. A. Cox, D. D i x i t , and J. W. Anderson. 1976. Accumulat ion and re lease o f petro leum de r i ved aromat ic hydrocarbons by f o u r species o f marine animals. Mar. B i o l . 38: 279-298.

Nor th Ca ro l i na Bureau o f Spor t F i s h e r i e s and W i l d l i f e , Nor th Ca ro l i na W i l d l i f e Resources Commission, and V i r g i n i a Commission of Game and I n l a n d F i she r i es . 1965. Back Bay-Curr i t u c k Sound da ta r e p o r t . Vol . 1. 84 pp.

Odum, H. T. 1967. B i o l o g i c a l c i r c u i t s and t h e marine systems o f Texas. Pages 99-157 - i n T. A. Olsen and F. J. Burgess, eds. P o l l u t i o n and marine ecology. John W i l e y and Sons, New York.

Odum, H. T. , and B. J. Copeland. 1969. A f u n c t i o n a l c l a s s i f i c a t i o n o f t h e coas ta l eco log i ca l systems. Pages 9-86 H. T. Odum, B. J. Copeland, and E. A. McMahan, eds. Coastal eco log i ca l systems o f t h e

U.S. Rep. Fed. Water P o l l u t . Cont ro l Admin., Washington, D. C.

OIHeeron, M. K. 1966. Some aspects o f t h e ecology of Rangia cuneata (Gray). M.S. Thesis. Texas A&M U n i v e r s i t y , Col lege S ta t i on . 7 1 PP.

Olsen, L. A. 1972. Comparative f u n c t i o n a l morphology o f feed ing mechanisms i n Rangia cuneata (Gray) and Polymesoda c a r o m (Bosc). Proc. N a t l . S h e l l f i s h . Assoc. 63: 4. (Abs t r . )

Olsen, L. A. 1973. Food and feed ing i n r e l a t i o n t o the ecology o f two es tua r i ne c l arns, Rangia cuneata (Gray) and Polyrnesoda c a r o l i niana (Bosc). M. S. Thesis. F l o r i d a S ta te U n i v e r s i t y , Tal lahassee. 102 pp.

Olsen, L. A. 1976a. Inges ted m a t e r i a l i n two species o f es tua r i ne b i - va lves: Rangia cuneata (Gray) and Polymesoda c a r o l i niana (Bosc). Proc. N a t l . S h e l l f i s h . Assoc. 66: 103-104. (Abs t r . )

Olsen, L. A. 1976b. Reproduct ive cyc les o f Polymesoda c a r o l i n i a n a (Bosc) and Rangia cuneata (Gray) w i t h aspects o f d e s i c c a t i o n i n t h e a d u l t s and f e r t i 1 i z a t i o n and e a r l y l a r v a l stages i n Polymesoda -- 1 i n i ana . Ph. D. D i s s e r t a t i o n . F l o r i d a S ta te U n i v e r s i t y , Tal l a - hassee. 116 pp.

O t to , J . , and S. K. P ie rce . 1981a. Water balance systems o f Rangia cuneata: i o n i c and amino a c i d r e g u l a t i o n i n changing s a l i n i t i e s . Mar. B i o l . 61:185-192.

abundance o f Rangia cuneata. U.S. F i s h W i l d l . Serv. Bur. Commer. - . .

Fish. C i r c . 246: 35-36.

Parker , R. H. 1955. Changes i n t h e i n v e r t e b r a t e fauna, apparen t ly a t t r i b u t a b l e t o s a l i n i t y changes, i n - the bays o f c e n t r a l Texas. J. Pa leonto l . 29: 193-211.

Parker , R. H. 1956. Macro- i n v e r t e b r a t e assemblages as i n d i c a t o r s o f sedimentary environments i n eas t M i s s i s s i p p i d e l t a reg ion . Am. Assoc. P e t r o l . Geol . B u l l . 40: 295-376.

Parker, R. H. 1959. Macro- i n v e r t e b r a t e assemblages o f c e n t r a l Texas coas ta l bays and Laguna Madre. Am. Assoc. P e t r o l . Geol. B u l l . 43: 2100-2166.

Parker, R. H. 1960. Ecology and d i s t r i b u t i o n a l p a t t e r n s o f marine macro- inver tebrates, no r the rn G u l f o f Mexico. Pages 302-337 i n F. P. Shepard, ed. Recent sediments o f nor thwest G u l f o f Mexico. Am. Assoc. P e t r o l . Geol. B u l l . Tulsa, Okl a.

Pf i tzenmeyer, H. T., and K. G. Drobeck. 1964. The occurrence o f t h e b rack i sh water clam, Rangia cuneata, i n t h e Potomac R i ve r , Mary1 and. Chesapeake Sc i . 5: 209-215.

Pu l l ey , T. E. 1952. An i l l u s t r a t e d check l i s t o f marine mol lusks o f Texas. Tex. J. Sc i . 4:167-199.

Remane, A. , and C. Schl i epe r . 1971. B io l ogy o f b rack i sh water. John W i l e y and Sons, New York. 372 pp.

O t to , J . , and S. K. P ie rce . 1981b. An Richards, H. G. 1939. Marine i n t e r a c t i o n o f e x t r a - and i n t r a - P le is tocene o f t he g u l f coas ta l c e l l u l a r osmoregul a t o r y mechani sms p l a i n : Alabama, M i s s i s s i p p i and i n t he b i v a l v e mol lusc Rangia Louis iana. Am. Assoc. P e t r o l . cuneata. Mar. B i o l . 61: 192-198. Geol . B u l l . 50: 297-316.

Parker, J. C. 1966. Bottom fauna Rogers, P. , and A. Garcia-Cubas. 1981. s tudy -- d i s t r i b u t i o n and r e l a t i v e E v o l u t i o n gonadica a n i v e l

h i s t o l o g i c o de Rangia cuneata (Gray, 1831) de l a Laguna Pon, Campeche, Mexico (Mol l usca: B i v a l v i a ) . Am. I n s t . Cienc. del Mar. Limnol. , Univ. Nat. Auton, Mexico. 8: 1-20.

Ruiz, H. E. 1975. Estudio eco log ico p r e l i m i n a r de l a s almegas comerci a1 es del s i stema 1 agunar de Terminos, Campeche, Rangia cuneata (Gray, 1831). Tesi s p ro fess iona l , Univ. Nat. Auton, Mexico, 80 pp. ( c i t e d i n Rogers and Garcia-Cubas 1981).

Sikora, W. B., J. P. S ikora, and A. McK. P r i o r . 1981. Environmental e f f e c t s of hyd rau l i c dredging f o r clam s h e l l s i n Lake Pontchar t ra in , Louisiana. Publ. No. LSU-CEL-81- 18. U.S. Army Corps o f Engineers, New Orleans D i s t r i c t . Cont rac t Rep. No. DACW29-79-C-0099. 140 PP.

S i kora, W. B. , and J. P. S i kora. 1982. Eco log ica l c h a r a c t e r i z a t i o n o f t he ben th i c community o f Lake Pont- c h a r t r a i n , Louisiana. Publ. No. LSU-CEL-82-05. U. S. Army Corps o f Engineers, New Orleans D i s t r i c t . Contract Rep. No. DACW29-79-C-0099. 214 pp.

Rangia cuneata Gray i n coas ta l waters o f Alabama. Ala. Mar. Resour. B u l l . 10: 9-16.

Tarver, J. W. 1972. Occurrence, d i s - t r i b u t i o n and dens i t y o f Rangia cuneata i n Lakes Pon tcha r t ra in and Maurepas, Louisiana. La. W i l d l . F ish. Comm. Tech. B u l l . No. 1. 8 PP.

Tarver , J. W . , and R. J. Dugas. 1973. A s tudy o f t he clam Rangia cuneata, i n Lake Pon tcha r t ra in and Lake Maurepas, Louis iana. La. W i l d l . F ish. Comm. Tech. B u l l . No. 5. 9 7 p p .

Tay lo r , J. L. 1978. Eva lua t ion o f dredging and open water d isposa l on benth ic environments: G u l f I n t r a c o a s t a l Waterway -- Apal a- c h i c o l a Bay, F l o r i d a t o Lake Borgne, Louis iana. Cont rac t Report t o U.S. Army Corps o f Engineers, Mobi le D i s t r i c t , Mobi le , Ala. 51 pp.

Tenore, K. R., D. B. Horton, and T. W. Duke. 1968. E f fec t s o f bottom subs t ra te on the b rack i sh water b i v a l v e Rangia cuneata. Chesapeake Sc i . 9:238-248.

Simpson, J - K- and J . U.S. Department o f Commerce. 1971. Awapara. 1959. Free amino ac ids F ishery s t a t i s t i c s o f the Un i ted i n some aquat ic inver tebra tes . States 1968. U.S. Gov. P r i n t . B i o l . B u l l . (Woods Hole) 117:- O f f . , Washington, D.C. Dig. 62. 371-381. 189 pp.

Singley, J. A. 1893. Con t r i bu t i ons t o Wass, M., and D. the na tu ra l h i s t o r y o f Texas.

1970. Marsh clams be l i eved p o t e n t i a l food

Pa r t I. Texas mollusca. Annu. Rep. Geol. Sur. Tex. 4:297-343. 2: supply. 1. B u l l . Va. I n s t . Mar. Sci .

Suttkus, R. D. , R . M. Da rne l l , and J. H. Da rne l l . 1954. B i o l o g i c a l Wells, H. W. 1961. The fauna o f study of Lake Pontchar t ra i n. oys te r beds, w i t h spec ia l (annual r e p o r t 1953-54). Tulane re fe rence t o t he s a l i n i t y f a c t o r . U n i v e r s i t y , New Orleans, La. 59 Ecol . Monogr. 31: 239-266. PP.

Wolfe, D. A. , and E. N. Petteway. Swingle, H. A. , and 0. G. Bland. 1974. 1968. Growth o f Raygia cuneata

D i s t r i b u t i o n o f the es tua r i ne clam Gray. Chesapeake Sci . 9: 99-102.

Woodburn, K. D. 1962. Clams and oys te r s i n C h a r l o t t e County and

v i c i n i t y . F la . Board Conserv. Mar. Lab. (FBCML) No. 62. 29 pp.

SOY72 -101

Ranqia 7. Authoris) I L C.rforrnin. Onsnlzation nast. rm

REPORT OOCUMENTATlON 1. "Emcn 2.

PACE I B i 01 oq i ca1 Report 82( 11.3114 - I

4. m l e and S,MI~I~

Species P r o f i l e s : L i f e Hi s t o r i e s and Environmental Requirements o f Coastal Fishes and Inve r teb ra tes (Gul f o f Mexico) -- Common

1 - - - - -. . .-.

Mark W. LaSal le and Armando A. de l a Cruz e. C.rformln( Orlanlzatlon Nama and Mdrass 1 10. ~ m i ~ / ~ a s r ~ w o r ~ t Unit NO.

3. n b ~ ~ * ~ s Accesston NO

L n.0.( 0.t.

A p r i l 1985 6.

I Department o f B i 01 og i ca l Sciences 1 I P.O. Drawer GY M i s s i s s i p p i S ta te U n i v e r s i t y M i s s i s s i p p i S ta te , MS 39 762

1% s V o n ~ n ( Orlanlutlon Name and Addma

Nat iona l Coastal Ecosystems Team U.S. Army Corps o f Engineers F ish and W i l d l i f e Serv ice Waterways Experiment S t a t i o n U.S. Department o f t h e I n t e r i o r P.O. Box 631 Washington, DC 20240 Vicksburg , MS 39180

*U.S. Army Corps o f Engineers Report No. TR EL-82-4 1L Abctnc( (Uml(: 100 word.)

Species p r o f i l e s a re 1 i t e r a t u r e summaries o f t h e taxonomy, morphology, range, 1 i f e h i s t o r y , and environmental requirements o f coasta l aqua t i c species. They a r e designed t o a s s i s t i n environmental impact assessment. The common rang ia (Rangia cuneata) i s a common i n h a b i t a n t o f shallow, low sal i n i t y ( z e r o t o 18 pp t ) e s t u a r i e s a long the no r the rn Gu l f of Mexico. The popu la t i on d e n s i t y o f rang ia may exceed 1000 clams/m2. Rangia spawn between March and November, f o l l o w i n g a sudden r i s e 'or f a 1 1 o f sal i n i t y o f 5 t o 10 ppt . Juven i l e clams develop r a p i d l y , s e t t l i n g a f t e r about 7 days. Juven i l es t o l e r a t e s a l i n i t y and temperature extremes o f 2 t o 20 p p t and 8 t o 32 "C. The growth r a t e o f clams ranges from zero t o 20 mm per year depending on cond i t i ons . Clams may l i v e 15 yea rs o r more, a t t a i n i n g a maximum l e n g t h o f about 94 mm. Rangia are found i n a wide range o f subs t ra te from sand t o s o f t mud. Rangia are f i l t e r feeders, i n g e s t i n g l a r g e amounts o f d e t r i t u s and phytoplankton, and a re t h e prey o f a l a r g e number o f f i s h , crustaceans, mol lusks , and ducks. Deposits o f f o s s i l s h e l l m a t e r i a l a re dredged f o r a number o f i n d u s t r i a l purposes.

Estuar ies Clams Dredging

b. IdentlRenlOp.n.Endad Terms

Common rang i a L i f e h i s t o r y Rangia cuneata Trophic ecology Sal i n i ty requirements Popu la t i on d e n s i t y Spawni ng h a b i t s

C. COUTl Fialdltmup

1L Avallablllty Statamant

Unl i m i t e d

Sea ANSI-239.18) OCTIONAL FORM 272 (4-71 (Forrmrly NTIS-35) D.par(ment ol Commarca

19. kcurbty Class (Th~s RewrO

Unc lass i f i ed 20. Suur' %F13rn*Fd

21. No. of Paacs

16 -- P. ?rice

. REGION 1 - - Reejonal Director

u.5. Fish and Wildlife Service Lloyd Five Hundred Building, Suite 1692 500 N.E. Multnomah Street Portland, Oregon 97232

REGION 4 Regional Director U.S. Fish and Wildlife Service Richard B. Russell Building 75 Spring Street, S.W. Atlanta, Georgia 30303

REGION 2 REGION 3 Regional Director Regional Director U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service P.O. Box 1306 Federal Building, Fort Snelling Albuquerque, New Mexico 87 103 Twin Cities, Minnesota 55 I l l

REGION 5 REGION 6 Regional Director Regional Director U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service One Gateway Center P.O. Box 25486 Newton Corner, Massachusetts 02 158 ,Denver Federal Center

Denver, Colorado 80225

REGION 7 Regional Director U.S. Fish and Wildlife Service 101 1 E. Tudor Road Anchorage, Alaska 99503

------a

7 OF THE ....-..-. U.S. FISH AND WILDLIFE SERVICE

As the Nation's principal consewation agency, the Department of the Interior has mpon- sibility for most of our.nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving theenvironmental and cultural values of our national park and historical places, and providing for the enjoyment of life through outdoor recreation. The Department as- sesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration.