m C E COPY Do Not Remove from the L!$wN

U. S, Fish and Wildlife Sawk@ Biological Report 82 (1 1.35) National Wetlands Resrarek ~ Q R M ~ TR EL.82.4 March 1985 700 Cajun Dome Boulevard

Lofayette, Louisiana 70506

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

GRASS SHRIMP

Fish and Wildlife Service Coastal Ecology Group

Waterways Experiment Station

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

T h i s i s one o f t h e f i r s t r e p o r t s t o be p u b l i s h e d i n t h e new " B i o l o g i c a l R e p o r t " s e r i e s . T h i s t e c h n i c a l r e p o r t s e r i e s , p u b l i s h e d b y t h e Resea rch and Deve lopmen t b r a n c h o f t h e U.S. F i s h and W i l d l i f e S e r v i c e , r e p l a c e s t h e "FWS/OBS1I s e r i e s pub1 i s h e d f r o m 1976 t o September 1984. The B i o l o g - i c a l R e p o r t s e r i e s i s d e s i g n e d f o r t h e r a p i d p u b l i c a t i o n o f r e p o r t s w i t h an a p p l i c a t i o n o r i e n t a t i o n , and i t c o n t i n u e s t h e f o c u s o f t h e FWS/OBS s e r i e s on r e s o u r c e management i s s u e s and f i s h and w i l d 1 i f e needs .

B i o l o g i c a l Repor t 82(11.35 ) TR EL-82-4 March 1985

Species P r o f i l e s : L i f e H i s t o r i e s and Envi ronmenta l Requirements o f .Coasta l F ishes and I n v e r t e b r a t e s (Gu l f o f Mexico)

GRASS SHRIMP

Gary Anderson Department o f B i o l o g i c a l Sciences

U n i v e r s i t y o f Southern M i s s i s s i p p i Ha t t i e sbu rg , MS 39406-5018

P r o j e c t Manager L a r r y Shanks

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 U. S. Army Corps o f Engineers Waterways Experiment S t a t i o n

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 Se rv i ce

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

This se r i es should be referenced as fo l lows:

U.S. F i sh and W i l d l i f e Service. 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 environmental requirements o f coas ta l f i shes and inver tebra tes . U. S. F i s h Wi ld l . Serv. B i o l . Rep. 82(11). U.S. Army Corps o f Engineers, TR EL-82-4.

This p r o f i l e should be c i t e d as fo l lows:

Anderson, G. 1985. Species p r o f i l e s : 1 i f e h i s t o r i e s and environmental requ i re - ments o f coasta l f i shes and i nve r teb ra tes (Gu l f o f Mexico) -- grass shrimp. U.S. F i sh Wi ld l . Serv. B i o l . Rep. 82(11.35) U.S. Army Corps o f Engineers, TR EL-82-4. 19 pp.

PREFACE

This species p r o f i l e i s one o f a se r i es on coasta l aquat ic organisms, p r i n c i p a l l y f i s h , o f sport , commercial, o r eco log ica l importance. The p r o f i l es are designed t o provide coasta l managers, engineers, 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 the b i 01 og i c a l c h a r a c t e r i s t i c s and environmental requ i re - ments o f t he species and t o descr ibe how populat ions o f the species may be expected to reac t t o environmental changes caused by coasta l development. Each p r o f i l e has sect ions on taxonomy, 1 i f e h i s t o r y , eco log ica l ro le , environmental requirements, and economic importance, i f appl i c a b l e. A t h ree - r i ng b inde r i s used f o r t h i s ser ies so t h a t new p r o f i l e s can be added as they are prepared. This p r o j e c t i s j o i n t l y planned and f inanced by the U.S. Army Corps o f Engineers and the U.S. F ish and W i l d l i f e Service.

Suggestions o r quest ions regard ing t h i s r e p o r t should be d i r e c t e d t o one o f t he f o l l o w i n g addresses.

I n fo rma t ion Trans fer Special i s t Nat ional Coastal Ecosystems Team U.S. F ish and W i l d l i f e Serv ice NASA-Sl i d e l 1 Computer Compl ex 1010 Gause Boulevard Sl i d e l 1 , LA 70458

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

CONVERSION TABLE

M e t r i c t o U.S. Customary

Mu1 t i p l y & To Obta in

m i l 1 imeters (m) cent imeters (an) meters (m) k i 1 m e t e r s ( km)

2 square meters (m ) square k i 1 m e t e r s ( km2) hec tares (ha)

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

m i l 1 igrams (mg) grams ( g ) k i lograms ( k ) m e t r i c tons q t ) m e t r i c tons k i 1 ocal o r i es ( kcal )

inches inches f e e t m i l es

square f e e t square m i l es acres

gal 1 ons cub ic f e e t ac re - fee t

ounces ounces pounds pounds s h o r t tons B r i t i s h thermal u n i t s

Cel s i u s degrees 1.8(OC) + 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 f a thorns 1.829 m i l e s (m i ) 1.609 nau t i ca l m i les ( m i ) 1.852

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

gal 1 ons (ga l ) cub ic f e e t ( f t 3 ) acre- f e e t

m i l 1 imeters cent imeters meters meters k i l ometers k i 1 ometers

square meters hectares square k i l ometers

1 i t e r s cub i c meters cubic meters

ounces (02) 28.35 grams pounds ( I b ) 0.4536 k i 1 ograms s h o r t tons ( t o n ) 0.9072 m e t r i c tons B r i t i s h thermal u n i t s ( B t u ) 0.2520 k i 1 ocal o r i e s

Fahrenhei t degrees 0.5556(OF - 32) Ce ls ius degrees

i v

CONTENTS

Page

PREFACE ........................................................... iii .................................................. CONVERSION TABLE i v

ACKNOWLEDGMENTS ................................................... v i

....................................... NOMENCLATURE/TAXONOMY/RANGE 1 .................................... MORPHOLOGY/IDENTIFICATION AIDS 2 .................................... REASON FOR INCLUSION I N SERIES 2

...................................................... LIFE HISTORY 4 ........................................................ Spawning 4

Fecund i t y ....................................................... 4 Development o f Larvae ........................................... 4

........................................ Ma tu ra t i on and L i f e Span 5 ECOLOGICAL ROLE ................................................... 5

..................................................... Food H a b i t s 5 ....................................................... Preda t i on 6 ....................................................... Pa ras i t es 6 .............................................. Behav io ra l Ecology 6 ............................................ GROWTH CHARACTERISTICS 7

ENVIRONMENTAL REQUIREMENTS ........................................ 8 Aquat ic Vegeta t ion ........................................ 8 S a l i n i t y ........................................................ 9

Brackish-Water shr imp ........................................ 8 Freshwater shrimp ............................................ 9 ............................................... Water Temperature 9

Disso lved Oxygen ................................................ 10 ................................................ Phys ica l Fac to rs 10 ....................................................... Bioassays 11

LITERATURE CITED .................................................. 13

ACKNOWLEDGMENTS

I am g r a t e f u l f o r rev iews and suggest ions by R ichard Heard, Gu l f Coast Research Laboratory , Ocean Springs, M i s s i s s i p p i ; Henry Tatum, U.S. Army Corps o f Engineers Waterways Experiment S ta t i on , Vicksburg, M i s s i s s i p p i ; and Steven Ross, Department of B i o l o g i c a l Sciences, U n i v e r s i t y o f Southern M i s s i s s i p p i , Ha t t iesburg , M i s s i s s i p p i .

Figure 1. Grass shrimp. a. Palaemonetes pugio; b-d, second chela o f P. pugio, P. in termedius and P. vu lga r i s , respec t i ve l y ; e-h, a n t e r i o r carapace and rosFrum o f P. p a l udosus, P. kadiakensis, P. vu lga r i s , and Macrobrachium ohione, respec t i ve l y ; i- j, antennule o f "b rack ish water" and " f reshwater" grass shrimp, respect ive ly . Scale o f drawings t o specimens i n mm i s (a) 7 t o 1, (b-d) 16 t o 1, (e-g) 4 t o 1, (h) 1.6 t o 1, and (i-j) 2 t o 1.

GRASS SHRIMP

..................... NOMENCLATlIRE/TAXONOMY/RANGE Subphylum Crustacea ................... C l ass.. .Ma1 acostraca

S c i e n t i f i c names ........ Palaemonetes Order .......................... Decapoda pugio; P. vu lga r i s ; P. intermedius; Fami l y . . .................. .Pal aemonidae P. palud>sus; P. k a d i a e n s i s. -

Common name ............. Grass shrimp Geographic range and speciat ion: The (Figure 1). grass shrimp i n t h e G u l f o f Mexico

Other names ........... Jumpers, g lass area c o n s i s t of f i v e species, a l l shrimp, popcorn shrimp, g lass prawns, r e l a t i v e l y s i m i l a r i n morphological hardbacks. c h a r a c t e r i s t i c s and most w i t h over-

l app ing d i s t r i b u t i o n . Because o f t h e i r s i m i l a r i t i e s , these species a re o f t e n m i s i d e n t i f i e d o r lumped as - P. vu l g a r i s.

A l though P. paludosus and P. kadiakensi s a r e p r i m a r i l y f reshwater species, bo th a r e somewhat t o l e r a n t o f mesohal i ne c o n d i t i o n s (Maguire 1961; Dobkin and Manning 1964; S t ren th 1976) and may be encountered i n bo th f reshwater and brack ish-water t i d a l marshes ( S w i ng l e 1971; Christmas and Langley 1973; Heard 1982).

MORPHOLOGY/IDENTIFICATION AIDS

Most o f t h e i n fo rma t i on sum- mar ized i n t h i s s e c t i o n i s taken f rom H o l t h u i s (1952), Wi l l i ams (1965), Wood (1974), and Heard (1982).

Several d i agnos t i c f ea tu res d i s t i n g u i s h t h e car idean shrimps, t o which t h e genus Pal aemonetes belongs, f rom t h e penaeidean shr~mps. I n t h e car idean forms, t h e p l e u r a o f t h e second abdominal somi t e over1 ap those o f t h e f i r s t , and t h e t h i r d wa lk ing l egs l ack claws o r chelae (F igu re l a ) . Palaemonetes spp. and o the r members o f t h e tami l y Palaemonidae may be d i s t i n g u i s h e d f rom members o f t h e f ami l i e s Alpheidae, Processidae, and H ippo l y t i dae by having t h e second wa lk ing l e g w i t h an u n j o i n t e d carpus ( t h e segment j u s t prox imal t o t h e che la ) . The absence o f mandibular pa lps i n Pal aemonetes d i s t i ngu i shes t h i s aenus f rom t h e o the r palaemonid - genera Macrobrachi um and Pal aemon. Furthermore. un l i k e Pal aemonetes. ~ a c r o b r a c h i um bears hepa t i c spine; 7 t i g u r e l h ) and palaemon f l o r i d a n u s has a prominent s t r i p e d p a t t e r n on t h e carapace and abdomen.

Other morphologica l f ea tu res o f Palaemonetes, as w e l l as many o the r car idean genera and f a m i l i e s , i nc l ude t h e f o l lowing: we1 l-developed ros t rum bear ing bo th dorsa l and v e n t r a l teeth, a smooth carapace and abdomen, rounded

abdominal p l e u r a 1-4, we1 1 -developed eyes w i t h g l obu la r pigmented corneas, wel l -developed spines on t h e t e l s o n (two p a i r s d o r s a l l y , two p a i r s p o s t e r i o r l y ) , and c h e l a t e wa lk ing legs 1-2 ( t h e second l egs are s t ronger than t h e f i r s t ) . Grass shrimp are t ransparen t t o y e l l o w i s h brown. Few exceed 50 mn i n t o t a l leng th . Males can be separated f rom females by t h e presence o f t h e appendix mascul i n a at tached t o t h e appendix i n t e r n a on t h e endopod o f t h e second p a i r o f pleopods. Also, t h e endopod o f t h e f i r s t pleopod i s l a r g e r i n males than i n females of t h e same age. A d d i t i o n a l d e t a i l s were p rov ided by H o l t h u i s (1952) and W i 11 i ams (1965). Selected morpho- l o g i c a l f ea tu res o f adu l t s o f t h e f i v e species o f Palaemonetes comnon t o waters o f t h e Gu l f o f Mexico are compared i n F igu re l a through l j and Table 1. However, these f ea tu res cannot be used t o d i s t i n g u i s h between j u v e n i l e s o f t h e brack ish-water forms of P. vu lga r i s , P. in termedius, and P. pugio -(Boston %d Provenzano 1 9 8 g . E Z E n a l g e n i t a l i c d e t a i l s o f males may a l s o be used t o d i s t i n g u i s h between t h e f i v e species (F leming 1969).

REASON FOR INCLUSION I N SERIES

Brack ish water Pal aemonetes are among t h e most w ide l y d i s t r i b u t e d , abundant, and conspicuous o f t h e shal low water ben th i c macro inver te- b ra tes i n t h e es tua r i es o f t h e A t l a n t i c and Gu l f Coasts (Wood 1967; Odum and Heald 1972; Welsh 1975; S i ko ra 1977). Although grass shrimp have o n l y l i m i t e d value as f i s h b a i t (Huner 1979) o r food f o r c u l t u r e d f i s h o r humans, t h e i r eco log i ca l importance i s unquestioned. Grass shrimp have been e x t e n s i v e l y documented as p rey o f f i shes (Gunter 1945; Darnel1 1958; Diener e t a l . 1974; Overs t ree t and Heard 1982) and o t h e r ca rn i vo res (Heard 1982) and t hey a re ins t rumenta l a l so i n t r a n s p o r t i n g energy and n u t r i e n t s between va r i ous e s t u a r i n e t r o p h i c l e v e l s : p r imary producers, decomposers, carn ivores , and d e t r i t i v o r e s (Johannes and Satomi 1966;

Table 1. Summary o f morpho log ica l d i f f e r e n c e s between f i v e spec ies o f Palaemonetes ( g r a s s shr imp) i n t h e c o a s t a l wa te rs o f t h e Gul f o f Mexico ( H o l t h i u s 1952; W i l l i a m s 1965).

Characters - P. v u l g a r i s - P. i n t e r m e d i u s P. p u g i o - - P. pa ludosus - P. k a d i a k e n s i s -

Number o f t e e t h 21 1 110 010 010 010 on d a c t y l u s ; f i x e d f i n g e r o f ( F i g u r e I d ) ( F i g u r e l c ) ( F i g u r e l b ) ( F i g u r e l b ) ( F i g u r e l b ) second l e g

Ros t ra1 t e e t h 8-11 on d o r s a l 7-10 on d o r s a l 7-10 on d o r s a l 6-8 on d o r s a l 6-8 on d o r s a l s u r f ace; 1 on s u r f ace; 1 on su r face ; t i p su r face ; t i p su r face ; t i p t i p ; 3-5 on t i p ; 4-5 on naked; 2-4 on naked; 3-4 on naked; 2-3 on v e n t r a l s u r f a c e v e n t r a l s u r f a c e v e n t r a l s u r f a c e v e n t r a l s u r f ace v e n t r a l s u r f ace ( F i g u r e l g ) ( F i g u r e l a ) ( F i g u r e l e ) ( F i g u r e I f )

Upper antennul a r Fused p a r t o f t h e two rami s h o r t e r t h a n f r e e p a r t Fused p a r t o f t h e two rami l o n g e r fl age1 1um ( F i g u r e l i ) t h a n f r e e p a r t ( F i g u r e l j )

P o s i t i o n o f Cons i der ab l y b ranch i o s t e g a l On a n t e r o v e n t r a l p a r t o f b r a n c h i o s t e g a l groove ( F i g u r e l a , l e , l g ) v e n t r a d t o s p i n e b r a n c h i o s t e g a l

groove ( F i g u r e I f )

Approximate 4 2 maximum t o t a l l e n g t h (mm)

Number, s i z e , Numerous, sma l l , u s u a l l y g r a y i s h brown and c o l o r of eggs

Few, 1 arge, u s u a l l y g r e e n i s h

Adams and Angelov ic 1970; Welsh 1975; Morgan 1980).

LIFE HISTORY

Spawning

The spawning season of grass shr imp extends from February through October b u t may v a r y w i t h species and geograph ica l l o c a t ion. An excep t ion i s P. paludosus, which spawns a l l year i n - southern t l o r i d a (Dobkin 1963). I n t h e prespawning female, t h e r i p e n i n g o v a r i e s are d i sce rnab le as g reen ish o r g r a y i s h brown masses o f t i s s u e do rsa l and p o s t e r i o r t o t h e stomach, and a d d i t i o n a l setae develop on t h e v e n t r a l su r f ace of t h e abdomen and thorax . The female 's m o l t i n g c o n d i t i o n and subsequent mat ing and spawning were descr ibed f o r P. v u l g a r i s by Burkenroad (1947). He- repor ted ' t h a t a f t e r mo l t i ng , t h e female i s r e c e p t i v e t o t h e male b u t t h a t apparen t l y t h e male recognizes her c o n d i t i o n o n l y i f p h y s i c a l con tac t i s made w i t h her exoskeleton.

t h e i n n e r membrane, s t r u g g l i n g by t he 1 a rva (protozoea) , and v e n t i 1 a t o r y movements by t h e female a s s i s t i n f r e e i n g t h e l a r v a f rom t h e egg membrane (Davis 1965). The female mo l t s aga in w i t h i n a few days a f t e r spawning and may produce an a d d i t i o n a l brood, depending on t h e species o r t ime o f spawning (Broad and Hubschman 1963; Know1 t o n and W i l l i ams 1970; Beck and Cowel 1 1976).

Fecund i ty

The f e c u n d i t y o f P. pug io i n Rhode I s l a n d i s g r e a t e r than t h a t o f o t h e r shr imp popu la t i ons t h a t have been s tud ied . For example, i n June, t h e average number o f eggs p e r female was 486 i n Rhode I s l a n d (Welsh 1975); 372 i n Texas (Wood 1967); and up t o 247 i n South Carol i na (S i ko ra 1977). There was a s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n between t h e l e n g t h ( X ) o f an ov igerous female and t h e number o f eggs (Y). Wood (1967) r epo r t ed t h e r e l a t i o n t o be l o g Y = 1 . 1 9 + 0 . 0 4 0 8 X . E g g c o u n t s o f P. pa ludosus i n F l o r i d a ranged from - o n l y 8 t o 85; l o g Y = 0.6288 + 0.0294 X (Beck and Cowell 1976).

Dur inq copu la t ion , which must occur w i t h i n 7 h a f t e r mo l t i ng , t he Development o f Larvae v e n t r a l sur faces o f t h e ~ a r t n e r s a r e p o s i t i o n e d so t h a t t h e i r g e n i t a l aper tu res a re c l o s e toge ther . A spermatophore i s q u i c k l y ex t ruded by t h e male on to t h e g e n i t a l s t e r n i t e s o f t h e female where i t remains u n t i l o v i p o s i t i o n . Be fo re o v i p o s i t i o n , which occurs w i t h i n 7 h a f t e r sperm t r a n s f e r , p a r t of t h e spermatophore d i s s o l v e s (p robab l y due t o enzymatic sec re t i ons f rom t h e fema le 's o v i d u c t ) and t h e spermatozoa a re re leased. Ova a re f e r t i l i z e d e x t e r n a l l y as t h e y are ext ruded, then mani pu l a ted aga ins t t h e pleopods and setae on t h e v e n t r a l su r f ace of t h e abdomen where t h e y adhere.

The eggs ha tch 12 t o 60 days a f t e r f e r t i l i z a t i o n , depending on species and geographica l 1 oca t ion . I n warmer c l ima tes , t h e i n c u b a t i o n p e r i o d i s u s u a l l y s h o r t e r . Osmotic swe l l i n g o f

Larvae a re p l a n k t o n i c and feed upon zooplankton, a1 gae, and d e t r i t u s . Depending on t he species and env i ron- mental c o n d i t i o n s , t h e r e may be f rom 3 t o 11 morphologica l l y d i s t i n c t s tages d u r i n g 1 a r v a l development. T r a n s i t i o n f rom one stage t o t h e nex t occurs d u r i n g mo l t i ng . I n t r a s p e c i f i c geno- t y p i c v a r i a b i l i t y i n t h e number o f 1 arvae and t h e morphology o f d i f f e r e n t stages may enhance d i spersa l (Sand i f e r and Smith 1979).

Larva l development has been descr ibed f o r each o f t h e f i v e species: P. v u l a a r i s and P. ~ u a i o bv Broad ~ 1 9 5 3 ~ kad i a k ~ s i s b y ~<oad and Hubschman (T963), P. paludosus by Dobkin (1963). and- P. i n te rmed ius by ~ubschman 'and Broad- (19 /4 ) . home a d d i t i o n a l i n t e r s p e c i f i c d i f f e r e n c e s i n l i f e h i s t o r i e s , m o d i f i e d f rom Hubschman

and Broad (1974), are shown i n Table 2. The morphology and behav io r of 1 arvae and p o s t l arvae d i f f e r . Larvae 1 ack l ong appendages and swim almost c o n t i n u o u s l y w i t h t h e head down and t h e d o r s a l su r f ace o r i e n t e d toward t h e d i r e c t i o n of h o r i z o n t a l movement. The d u r a t i o n of l a r v a l development may range from 11 days t o severa l months f o r P. pug io (F l oyd 1977), depending on env iTonETE i1 c o n d i t i o n s . The f i n a l l a r v a l s tage metamorphoses t o a p o s t l arva, which c l o s e l y resembles t h e a d u l t .

Ma tu ra t i on and L i f e S ~ a n

J u v e n i l e P. pug io mature when t h e y a re 1.5 t o 2 m T n t n d and about 15 t o 18 mm long; t h e i r l i f e span i s 6 t o

13 months (A l on and Stancyk 1982). The o l de r , o v e r w i n t e r i n g shr imp u s u a l l y spawn e a r l y i n t h e year and d i e by t h e nex t w i n t e r . Most young-of -t he-year spawn l a t e i n t h e year as adu l t s . Pos t l a r vae t h a t s u r v i v e t h e f a l l and w i n t e r spawn i n t h e f o l l o w i n g sp r i ng .

ECOLOGICAL ROLE

Food H a b i t s

Grass shrimp ea t a wide v a r i e t y o f aqua t i c foods. Depending on t h e a v a i l a b i l i t y of a p a r t i c u l a r f ood t h e y may be d e t r i t i v o r e s , p r ima ry consumers, o r secondary consumers (Odum and Heald 1972; Morgan 1980).

Table 2. Spawning season, f ecund i t y , l e n g t h s (mm) a t ha tch ing and a t metamor- phos is , and number o f l a r v a l mo l t s f o r Palaemonetes spp. i n t h e G u l f o f Mexico.

Fecund i t y Length (WII)~ (maximum ' -A t At Number o f 1 a r v a l .,

Species season i bse r ved ) ha t ch i ng metamorphosis mol t s a

P. v u l g a r i s - A p r i 1 -October b

No da ta

C P. pug io - - March-October 486 2.6 6.3 7-11

P. i ntermedi us May-September - 129 3.5 7.0

P. k a d i akensi s ~ e b r u a r ~ - O c t o b e r f 160 - 4.4 7.5 5- 8

P. paludosus - Year round h

a ~ a t a on l e n g t h a t ha tch ing and metamorphosis and number o f l a r v a l mol t s a r e from t h e f o l l o w i n g sources: P. v u l a r i s and P. pug io , Broad (1957); P. i n t e r - medius , Hubschman and Broad (-7&adiakenn - s, Broad and HubschmaT (m;

aludosus, Dobkin (1963). b ~ ~ d o w ~ ~ o k l i ams (1970). 'wood (1967). d ~ e l sh (1975). e ~ e c k and Cowel 1 (1976). f ~ h i t e (1949). '~eehean (1936). h ~ o b k i n (1963).

The fundamental r o l e o f grass shr imp as d e t r i t i v o r e s i s exp la ined b y Odum and Heal d (1972), We1 sh (1975), and Adams and Angelov ic (1970). As d e t r i t i v o r e s , grass shr imp a i d i n t h e mechanical breakdown of r e f r a c t o r y o rgan ic m a t e r i a l such as f i b r o u s p l a n t ma te r i a l s , as w e l l as a s s i m i l a t e t h e associated m i c r o f l o r a , m i c r o f auna, and f ung i (Adams and Ange lov ic 1970). The assimi 1 a t i o n o f d i sso l ved o rgan i c ma t t e r sorbed t o f i n e l y d i v i d e d p a r t i c u l a t e ma t t e r such as c l a y p a r t i c l e s i s impor tan t i n grass shrimp n u t r i t i o n (Odum and Heald 1972). Al though grass shrimp o f t e n l i v e among aquat i c macrophytes (Adams and Angelov ic 1970; L i v i n g s t o n e t a l . 1976; Heck and Or th 1980; Morgan 1980; Coen e t a l . 1981; Gore e t a l . 1981), t h e r e i s l i t t l e ev idence t h a t t h e macrophyte s t r u c t u r e i s a c t u a l l y consumed. More 1 i ke l y , g rass shrimp ea t and a s s i m i l a t e t h e e p i p h y t i c mi croalgae t h a t coa t t h e p l ant s t r u c t u r e (Morgan 1980). Grass shrimp a l so are p reda to rs o f meiofauna and smal l i n f aunal polychaetes, 01 igochaetes, nematodes (S i kora 1977; B e l l and Cou l l 1978; Chambers 1981), e p i p h y t i c fauna (Odum and Heald 1972; Morgan 1980), and even m o t i l e p rey such as mysids (Morgan 1980). As ep iben th i c p reda to rs and sediment d i s t u r b e r s , grass shr imp a1 t e r i n f auna l community s t r u c t u r e ( B e l l and Cou l l 1978; Knieb and S t i v e n 1982). For example, i n Nor th Ca ro l i na a sharp d e c l i n e i n t h e abumdance o f P. pug io due t o p reda t i on by murrmichogs (Fundulus h e t e r o c l i t u s ) b rought about s i g n i f i c a n t chanqes i n i nfaunal composit ion.

-

Preda t ion

I n es tua r i es , numerous f i s h species and o t h e r aqua t i c ca rn ivores , some o f which are va luab le s p o r t and commercial f i shes , ea t 1 arge q u a n t i t i e s o f grass shrimp. Grass shrimp are a l so eaten by forage f i s h e s such as Fundulus spp. (Ha r r i ng ton and Ha r r i ng ton 19/2; Welsh 1975; Knieb and S t i v e n 1982), which i n t u r n are preyed upon by l a r g e r f i shes .

As prey, g rass shrimp p l a y an impor tan t r o l e i n t h e t r a n s f e r of energy from t h e producer and decomposer l e v e l s t o h i ghe r consumer l e v e l s .

Grass shrimp f r e q u e n t l y i n h a b i t water near underwater s t r u c t u r e s and a re p a r t i c u l a r l y a t t r a c t e d t o dense stands o f underwater macrophytes. These stands n o t o n l y suppor t an abundance and d i v e r s i t y o f f ood f o r shrimp, b u t a l s o p rov i de a r e fuge from preda to rs . Grass shrimp are more prone t o p reda t i on when d i sp l aced f rom p r e f e r r e d s u b s t r a t a such as macrophytes (Coen e t a l . 1981; Heck and Thoman 1981) and oys te r s h e l l s (Thorp 1976).

Pa ras i t es

Grass shr imp are hos ts f o r numerous species of p a r a s i t e s and ectocommensals. The most abundant are c o c c i d i a (So l angi and Overs t ree t 1980), m i c rospo r i d i ans (Ove rs t r ee t and Weidner 1974), t rematodes (Heard and Overs t ree t 1983), isopods (Anderson 1977), and leeches (Ove rs t r ee t 1978). The b i o l o g y o f o t h e r h o s t - p a r a s i t e i n t e r r e l a t i o n - sh i ps i n v o l v i n g Pal aemonetes spp. were summarized by Johnson (1977) and Ove rs t r ee t (1978). Diseases and p a r a s i t e s do n o t appear t o be major f a c t o r s i n l i m i t i n g t h e abundance and growth o f g rass shrimp i n t h e Gu l f o f Mexico . Behavi o r a1 Ecology

F i e l d s t u d i e s have shown t h a t t h e movement and d i s t r i b u t i o n a l p a t t e r n s of g rass shr imp may be i n f l uenced by bo th pho toper iod and t i d a l cyc les . Swimminq o f European species; Pal aemonete; var ians. peaked i n morninq and eveninq ( ~ n t h e u n i s s e e t a l . 1971). The o n l y obse rva t i on on noc tu rna l movement o f P. pug io was documented by Shenker aiid Dean (1979), who r e p o r t e d t h a t some shrimp are b u r i e d i n t h e sediments d u r i n g day1 i g h t . These s tud ies , as w e l l as t h a t o f S i ko ra (1977), i n d i c a t e d t h a t grass shrimp i n t i d a l creeks m ig ra te seaward (downstream) o r d r i f t w i t h t h e c u r r e n t d u r i n g ebb t i d e s

Table 3. Mean d a i l y srowth increments and dur

migra te upstream i n t o t i d a l creeks i n g incoming t i d e s .

Dur ing l abo ra to ry experiments on agon i s t i c behavior i n P. pugio and P. vu lga r i s , females w e r F d Z i i G n t ovFr males and l a r g e shrimp were dominant over smal ler ones. I n i n t e r s p e c i f i c pa i r ings , P. v u l g a r i s gene ra l l y dominated P .- pug-(Chars 1981), and P. v u l g a r i s m o w n t o d i sp lace P. pug i5 from the p r e f e r r e d s h e l l su6- s t ra tum (Thorp 1976). Such displacement may favo r coexistence between these two sympatr ic species by reducing the f u t u r e p o t e n t i a l f o r a g o n i s t i c behavior . D i s t r i b u t i o n a l d i f f e r e n c e s between two sympatr ic species are be1 ieved t o be caused by displacement o f P. v u l g a r i s by Palaemon f l o r i d a n u s from the p r e f e r r e d red a l g a l substratum (Coen e t a l . 1981).

GROWTH CHARACTER I STICS

Because popul a t i ons o f grass shrimp may produce more than two broods a year, length- f requency d i s t r i b u t i o n s may be polymodal and growth r a t e s are d i f f i c u l t t o cha rac te r i ze (S i ko ra 1977). Grass shrimp popu la t ion growth c h a r a c t e r i s t i c s have been described f o r P. pugio i n Texas (Wood 1967), South T a r o l i n a ( S i ko ra 1977; Alon and Stancyk 1982), North Carol i n a (Know1 t o n and W i l l iams 1970), and Rhode I s 1 and (Welsh 1975); and f o r P. paludosus i n F l o r i d a (Beck and Cowel l 1976). Growth r a t e s vary somewhat between species, sexes, hab i t a t s , and t imes o f year. These d i f f e rences are exemp l i f i ed i n p a r t by t h e d i f f e r e n t d a i l y growth r a t e s o f P. pugio f rom two popu la t ions i n Sou€h C a r o l i n a (Table 3 ) .

According t o Beck and Cowell (1976), P. paludosus grows 3.25 mm per month iKsummer and f a l l . I n Rhode I s l and , t h e l eng th o f P. pugio increased r a p i d l y from ~ u l f thEji$i September; females had then reached a t o t a l l eng th o f about 3 cm and males about 2.6 cm. The growth o f grass

(mm) o f ~a laemonetes-pug io from two h a b i t a t s i n South Caro l ina (da ta from Alon and Stancyk 1982).

Local i t y Season and sex Summer Winter North I n l e t

female 0.143 + 0.111 0.090 + 0.067 ma1 e 0.087 T - 0.060 0.086 T - 0.041

Minim Creek ternale 0.133 + 0.109 0.089 + 0.041 ma1 e 0.069 T - 0.036 0.068 T - 0.042

shrimp was n e g l i g i b l e f rom September t o May i n Rhode I s l a n d (Welsh 1975). I n cont ras t , one group o f P. pugio i n South Ca ro l i na i s born i%d F E E i i i t e d i n e a r l y spring, grows r a p i d l y du r i ng summer, and d ies be fore w in te r . A second group i s r e c r u i t e d i n l a t e summer, grows r a p i d l y i n autumn and again t h e f o l l o w i n g spring, and u s u a l l y d i e s by midsummer (Alon and Stancyk 1982). These age and growth c h a r a c t e r i s t i c s make i t d i f f i c u l t t o t a b u l a t e lengths o f grass shrimp o f d i f f e r e n t ages.

I n t h e southern and southeastern coas ta l waters o f t h e Un i ted States, ove rw in te r i ng P. pugio spawn i n l a t e February t h r o u g h M a r c h a t water temperatures o f 15" t o 20°C. Juven i les f rom t h e February-March hatch mature and spawn from l a t e summer ( Ju l y - August) t o November. By then the l eng th d i s t r i b u t i o n i s h i g h l y bimodal. Shrimp o f t h e summer-f a1 1 hatch mature f rom October t o February and reproduce du r i ng t h e f o l l o w i n g spr ing . Shrimp hatched i n sp r i ng grow f a s t e r than those hatched i n summer and f a l l bu t have a sho r te r l i f e span.

I n co lde r coas ta l waters, growth p a t t e r n s are d i f f e r e n t . I n Rhode Is land, t h i s species spawns o n l y once du r i ng May t o J u l y i n any one year. Length d i s t r i b u t i o n i s consequently unimodal throughout t h e year (Welsh 1975).

S a l i n i t y i s y e t another f a c t o r t h a t a f f e c t s growth. I n South Caro l ina , P. p u g i o matures and spawns a t a younger age i n h a b i t a t s w i t h r e l a t i v e l y h i g h s a l i n i t y t han i n those w i t h r e l a t i v e l y low s a l i n i t y (A lon and Stancyk 1982), b u t specimens c o l l e c t e d i n low s a l i n i t y waters were sma l l e r t han those f rom more s a l i n e waters (Wood 1967).

ENVIRONMENTAL REQUIREMENTS

Aauat i c Veaet a t i o n

Grass shrimp, macrophytes, and a lgae l i v e i n t h e same communities and are sub jec t t o many o f t h e same envi ronmenta l f a c t o r s (Beck and Cowell 1976; Thorp 1976; Morgan 1980; Coen e t a l . 1981; Heck and Thoman 1981). S tud ies i n F l o r i d a showed t h a t P. pug io was most abundant i n Tab- c h a r a c t e r i z e d by aqua t i c macrophytes, r e 1 a t i v e l y h igh t u r b i d i t i e s , and low s a l i n i t i e s ( L i v i ngston e t a1 . 1976).

Because grass shr imp depend on aquat i c vege ta t i on i n many coas ta l waters, a l t e r a t i o n s o f e s t u a r i e s t h a t des t roy vege ta t i on cou ld s e r i o u s l y reduce t h e i r abundance. I n one instance, we i r s b u i l t i n marshes t o b e n e f i t w i l d l i f e produced dense masses o f aqua t i c vege ta t i on t h a t suppor ted an abundance o f grass shr imp f a r h i ghe r than t h a t i n nearby l e s s densely vegetated waters (Weaver and Hol 1 oway 1974). I n another s tudy i n West Bay, Texas, dredging, bulkheading, and f i l l i n g of coas ta l marshes caused a permanent l o s s o f i n t e r t i d a l vege ta t ion . The r e d u c t i o n o f d e t r i t a l i n p u t i n t o t h e a d j o i n i n g aqua t i c systems caused a n o t i c e a b l e decrease i n abundance o f g rass shrimp (T ren t e t a l . 1976).

S a l i n i t v

The abundance o f f reshwater and b rack ish-wate r grass shrimp i n e s t u a r i e s i s c l e a r ev idence o f t h e i r

s u r v i v a l i n a wide range o f s a l i n i t i e s .

Brack i sh-water shrimp. F i e l d and l a b o r a t o r y s t u d i e s i n d i c a t e t h a t P. p u g i o a d u l t s t o l e r a t e s a l i n i t i e s from-0 t o 55 p p t b u t a r e most common i n s a l i n i t i e s o f 2 p p t t o 36 p p t (Wood 1967; Swingle 1971; Bowler and Seidenberg 1971; Christmas and Langl ey 1973; K i r b y and Knowl t o n 1976; Morgan 1980). The 96 h LDS0 values f o r a d u l t s a r e 0.5 and 44 p p t ( K i r b y and Knowlton 1976).

At tempts t o assess s a l i n i t y t o l e rances o f l a r v a e on a broad s c a l e have y i e l d e d mixed r e s u l t s . McKenney and Nef f (1979) were able t o r e a r n e a r l y 50% o f t h e P. pug io l a r v a e exposed t o a s a l i n 3 y 7 3 ppt, whereas, Broad and Hubschman (1962) r e p o r t e d poor s u r v i v a l of l a r v a e a t s a l i n i t i e s l e s s than 10 pp t . When l a r v a e were exposed t o a wide range of a r b i t r a r i l y se l ec ted s a l i n i t i e s , t h e low and h i gh s a l i n i t i e s r e q u i r e d t o k i l l 50% o f t h e l a r v a e d u r i n g a 96-h exposure (LD50) were 16 p p t and 46 ppt, r e s p e c t i v e l y ( K i r b y and Knowl t o n 1976). Optimum s a l i n i t y f o r complete l a r v a l development i s 20 t o 25 p p t (F loyd 1977; McKenney and Ne f f 1979; Knowlton and K i r b y 1984). Poss ib l e reasons f o r t h e c o n f l i c t i n g f i n d i n g s are d i f f e r e n c e s i n popu la t i ons i n d i f f e r e n t geographic l oca t i ons , and d i f f e r e n c e s i n 1 abora to ry procedures.

P. v u l g a r i s i s more t o l e r a n t o f h i gh T a l i n i t y water and l e s s t o l e r a n t of low s a l i n i t y water than i s P. pug io ( H o l t h u i s 1952; Knowlton and -Ail-Tiams 1970; Bowler and Seidenberg 1971; Thorp and Hoss 1975). A1 though Nagabus hanam (1961) r e p o r t e d t h a t s a l i n i t i e s as low as 3 p p t were l e t h a l t o a d u l t P. v u l g a r i s , t hey have been c o l l e c t e d i n f reshwater (Swingle 1971; Christmas and Langley 1973; B a r r e t t e t a l . 1978). Schoen and Knowl t o n (1977) r e p o r t e d 96-h LDs0 va lues o f 0.8 and 5 1 p p t f o r adu l t s . Larvae o f P. v u l g a r i s a r e l e s s t o l e r a n t o f low s a l in1 t y t han a r e adu l t s . Larvae t h r i v e a t s a l i n i t i e s

between 10 p p t and 30 p p t ; t h e optimum i s 20 p p t (Sand i f e r 1973). Larvae do n o t s u r v i v e a t s a l i n i t y extremes o f 5 and 35 p p t (Knowlton 1965; Schoen and Knowlton 1977). Larvae o f bo th P. p u g i o and P. v u l g a r i s s u r v i v e bes1, mature e a r l y , and o f t e n pass through fewer l a r v a l stages when s a l i n i t i e s a re near optimum (Sand i fe r 1973; F loyd 1977). I n t e r s p e c i f i c d i f f e r e n c e s i n s a l i n i t y t o l e rance i n e s t u a r i e s a re l i k e l y t o segregate P. pug io and P. v u l g a r i s (Bowler and seeidenberg 1971r, a l though b i o t i c i n t e r a c t i o n s such as compe t i t i on f o r food and space a re p robab l y more impo r tan t f o r segrega t ion and coex is tence (Thorp 1976).

A l though P. in te rmed ius i s euryha l i ne , i t has been c o l l e c t e d from waters w i t h s a l i n i t i e s o f 5 t o 39 p p t (Dobkin and Manning 1964). The l a r v a e t h r i v e a t s a l i n i t i e s o f 20 p p t b u t s u r v i v a l i s low a t s a l i n i t i e s l e s s t han 10 p p t (Broad and Hubschman 1962). The 1 arvae have been rea red a t s a l i n i ti es near 30 p p t (Hubschman and Broad 1974).

Freshwater shrimp. The two f reshwater s ~ e c i e s . P. D ~ ~ U ~ O S U S and P. . .

kad iakens is ,' o f t en -1 i b e i n b r a c k i ~ h wate rs (Christmas and Langl ey 1973).

P. paludosus was repo r t ed i n s a l i n i t i e s - o f 0 p p t t o 10 p p t by Tabb and Manning (1961), and one specimen was cap tu red i n a s a l i n i t y o f 25 p p t (Swingle 1971). I n a l a b o r a t o r y experiment, P. paludosus su rv i ved f o r 7 days a t -a s a l i n i t y o f 30 p p t b u t d i e d when t h e s a l i n i t y was r a i s e d t o 37 ppt . I n another exper iment , a d u l t P. kadia- kens is su r v i ved a t s a l i n i t i e s u p t o 0 p p t b u t d i e d a t 25 p p t (Maguire 1961; S t r e n t h 1976). Larvae a r e r e l a t i v e l y i n t o l e r a n t o f s a l i n i t i e s h i ghe r t han 5 p p t (Hubschman 1975; S t r e n t h 1976) b u t a r e more t o 1 e r a n t of h i ghe r s a l i n i ti es a f t e r t hey reach stage I V (Hubschman 1975).

The s a l i n i t y t o l e r a n c e o f grass shr imp i s summarized i n Table 4.

Water Temperature

Grass shr imp are eurythermal . I n coas ta l waters, P. pyg io t h r i v e s a t temperatures of 5" t o373 -C (Wood 1967; Christmas and Langley 1973), bu t s u r v i v a l i s g rea te r a t 18" t o 25°C. Growth i s most r a p i d i n waters a t temperatures above 30°C bu t drops r a p i d l y a t water temperature below 14°C (Wood 1967). Th i s species breeds a t

Table 4. S a l i n i t y t o l e r a n c e 1 i m i t s and opt ima ( p p t ) r e p o r t e d by va r i ous i n v e s t i g a t o r s (see t e x t d iscuss ion) f o r a d u l t and l a r v a l Palaemonetes.

Form and species Adu l ts Larvae L i m i t s Upt imum L i m i t s Upt imum

Freshwater forms

P. kad iakens is ?. paludosus -

Brack i sh-water forms

0-10 0 No da ta 0

P. in te rmed ius 5-39 No da ta 10-30 20 ?. pug io 1-55 4-16 3-31 2 5 P. - 7 i j l i j Z r - i ~ 1-51 No da ta 5- 35 20

temperatures o f 22" t o 27°C i n Rhode I s l a n d ( S a s t r y and Vargo 1977) and from 17" t o 38°C i n Texas (Wood 1967). P r e f e r r e d water t e m ~ e r a t u r e s ranqe from 5 " t o 35°C f o r P. v u l g a r i s and P. paludosus and from-10' t o 35°C f o r F. D ~ I U ~ O S U S (Chr is tmas and Lanqley 1973). TO^ k rance f o r warmer waters i s g r e a t e r f o r P. pug io t han - P. v u l g a r i s , b u t 60 th s p e c i e s are r e l a t i v e l y t o l e r a n t o f t h e hea t s t r e s s o f e f f l u e n t s f rom a power p l a n t (Chung 1977). The b reed ing temperatures f o r P. paludosus range f rom 18" t o 33°C TBeck and Lowe l l 1976).

P h y s i o l o g i c a l responses o f grass shr imp t o temperature i n d i c a t e t h a t P. v u l g a r i s a d u l t s (McFarland and Pickens 1-d P. pug io l a r v a e ( S a s t r y and Vargo 1 9 7 n a r e m e t a b 0 1 i c a l l y a c t i v e over a broad range o f water tempera- t u res , e x h i b i t i n g p h y s i o l o g i c a l compensation t o seasonal temperature changes.

Temperature t o l e r a n c e da ta f o r grass shr imp a re summarized i n Tab le 5.

D isso lved Oxvqen

D isso lved oxygen i s another f a c t o r t h a t he l ps r e g u l a t e t h e d i s t r i b u t i o n and abundance o f g rass shrimp. I n Lou i s i ana waters, P. v u l g a r i s and P. - pug io a re common i n d i s s o l v e d oxygen

(UU) concen t ra t i ons o f 6 t o 11 ppm ( B a r r e t t e t a l . 1978). I n Rhode I s 1 and, t h e m o r t a l i t y o f P. v u l g a r i s was h i ghe r t han t h a t o f P. p u g i o , when b o t h spec ies were c a g e d t o g e t h e r i n a hypox ic m i c r o h a b i t a t (DO = 0.3 ppm) d u r i n g a t i d a l c yc l e . I n t h e 1 abora to ry , a t oxygen concen t ra t i o n s lower t han 1 ppm, s u r v i v a l was h i qhe r i n P. pug io t han - i n P. v u l g a r i s a t - a l l t e s r temperatures (no t o 30°C). I n na tu re , 'grass shr imp sometimes' c l i m b ou t o f t h e water d u r i n g pe r i ods o f oxygen d e f i c i e n c y , espec i a1 l y d u r i n g warm summer n i g h t s , b u t such a t tempts t o avo id hypox ia can be e f f e c t i v e o n l y f o r a few hours (Pomeroy and Wieger t 1981). Resp i r a t o r y s t u d i e s i n d i c a t e d t h a t P. pug io i s an oxyconformer; i t s oxygen u i e decreases as oxygen t e n s i o n d e c l i n e s f rom 8 t o 2 ppm (Welsh 1975; D i l l o n 1983).

Phys i ca l Fac to r s

Grass shr imp u s u a l l y i n h a b i t t h e sha l lows near t h e w a t e r ' s edge b u t have been r e p o r t e d a t depths as g r e a t as 8 fathoms (W i l l i ams 1965). I n w i n t e r , d u r i n g temperature lows and i n summer, when wate r temperatures approach seasonal h ighs , P. p u g i o moves f rom sha l l ow t o r e l a t i v e i y deep wate r (Wood 1967). Thorp (1976) no ted t h a t t h e e x t e n t o f t h e movement o f grass shr imp among va r i ous depths o f t e n c o i n c i d e s w i t h t h e d i s t r i b u t i o n o f

Table 5. Temperature t o l e r a n c e range and opt ima (OC) r e p o r t e d f o r a d u l t and 1 a r v a l Pal aemonetes.

---. --- ---- -.- ---- A d u l t s Larvae

Species L i m i t s Optimum L i m i t s Optimum

P. paludosus 10-35' V . Dualo 5 -38asb F. G i $ j T r i s 5-35 No d a t a

No dafla No d a t a 15-35 ' f 20-30f 20-30 20

-- - Sources: m i s t m a s and Langley 1973; b - Beck and Cowel l 1976; c - Wood 1967; d - McKenney and N e f f 1979; e - F loyd 1977; f - Sand i f e r 1973

oys te r s h e l l substrates, which; i n some waters, a re p r e f e r r e d by P. pug io and P. vu lga r i s . Oyster beds prov lde food - and p ro tec t i on .

Grass shrimp are abundant where t u r b i d i t y i s r e l a t i v e l y high. This i s p a r t i c u l a r l y t r u e i n h a b i t a t s where water cu r ren ts tend t o keep sediments suspended, such as i n shal low t i d a l creeks o r near r i v e r mouths. T u r b i d i t y may prov ide some degree of p r o t e c t i o n from predators i n h a b i t a t s w i t h 1 i t t l e vegetat ion. I n l ess t u r b i d hab i ta t s , macrophytes a f f o r d p r o t e c t i o n from predators. A1 though L iv ings ton e t a1 . (1976) found t h a t grass shrimp abun- dance was p o s i t i v e l y c o r r e l a t e d w i t h t u r b i d i t y , t u r b i d i t y may no t be an environmental requirement. I n some hab i ta t s , grass shrimp have been observed i n c l e a r water such as i s o f t e n associated w i t h dense aquat ic vegeta t ion (Weaver and Holloway 1974).

Grass shrimp tend t o avo id f a s t cu r ren ts and migrate i n t he d i r e c t i o n o f t i d a l cu r ren ts (Antheunisse e t a l . 1971; S ikora 1977; Shenker and Dean 1979).

Bioassays

I n as much as grass shrimp have been recommended f o r use as bioassay t e s t organisms (American Pub1 i c Heal th Associat ion 1975), much i n fo rma t ion has been pub1 ished about morta l i t y and sub le tha l e f f e c t s of var ious tox i can ts on grass shrimp bu t on l y a few are mentioned here. Workers eva lua t i ng t h e e f f e c t s o f kepone and o the r i n s e c t i - c ides (heptachlor , toxaphene, d i e l d r i n , and endosulfan) conclude t h a t P. pug io adu l t s were u s u a l l y l ess sensiTive and showed a l esse r tendency t o bioconcen- t r a t e these t o x i c a n t s than d i d the f i s h t h a t were tes ted (Schimmel and Wilson 1977; Schimmel e t a l . 1977). For example, t he 96-h LDS0 values f o r kepone were 121 p g / l and 70 p g / l f o r P. u i o and f o r t he sheepshead minnow C r inodon var iegatus) . Bioconcen- ?-%

t r a t i o n f a c t o r s were 698 f o r t he shrimp and 1,548 f o r the minnow (Schimmel and

Wilson 1977). On the o ther hand, grass shrimp are much more s e n s i t i v e than f i s h t o end r i n (Tyler-Schroeder 1979), d i thiocarbamates (Rao e t a1 . 1982), var ious chlorophenols (Rao e t a l . 1981), and DDT and para th ion (Sanders 1972). On the bas is o f a study o f 12 i nsec t i c i des , E i s l e r (1969) concluded t h a t grass shrimp are more s e n s i t i v e t o organophosphorous i n s e c t i c i d e s , and less s e n s i t i v e t o several organo- c h l o r i n e i n s e c t i c i d e s a t h igh s a l i n i t y than a t low s a l i n i t y . Low temperatures enhanced the s u r v i v a l o f shrimp exposed t o bo th groups o f i nsec t i c i des . Also, f o r most organophosphorous compounds tes ted , crustaceans were more s e n s i t i v e than marine f i s h e s by several orders o f magnitude.

Heavy metals such as cadmium a re more t o x i c t o arass s h r i m ~ than t o mummichogs, FG~UI us heteroc l i t u s ( E i s l e r 1971). Concentrat ions o f heavy metals (mercury, cadmi um, and chromi umj a re acu te l y t o x i c t o a d u l t grass shrimp, usua l l y i n t he order o f 100 t o 1,000 ppb. Except i n areas o f sewage o r i n d u s t r i a l o u t f a l l s, such concen- t r a t i o n s f a r exceed those i n es tuar ies . Therefore, grass shrimp are too r e s i s t a n t t o be o f much value i n heavy metal bioassays (Vernberg e t a1 . 1977). Increased temperature o r decreased s a l i n i t y increases the s e n s i t i v i t y o f grass shrimp t o heavy metals (Fales 1978; Sunda e t a l . 1978). Sublethal e f f e c t s o f heavy metals on grass shrimp have inc luded l oss o f a predator avoidance response (Barthalmus 1977), developmental abnormal i ti es i n la rvae (Shealy and Sandi fer 1975), and a reduced t o 1 erance t o sa l i n i t y f 1 uctua- t i o n s (Middaugh and Floyd 1978).

Attempts have been made by Tatem (1976), Tatem e t a l . (1978), and D i l l o n (1982) t o evaluate t h e e f f e c t s o f exposure t o petroleum hydrocarbons on s u r v i v a l and var ious phys io log i ca l phenomena i n grass shrimp. Several conclusions have been drawn from t h i s research: (1) concentrat ions o f petroleum hydrocarbons normal l y found i n sa l twa te r (10 t o 20 ppb) and i t s

sediments a r e t o o l o w t o have a c u t e l y t o x i c e f f e c t s on g rass shrimp; ( 2 ) when sediments and wa te r a r e exposed c h r o n i c a l l y t o o i l p o l l u t i o n o r d u r i n g a l a r g e o i 1 s p i l l , hydrocarbon c o n c e n t r a t i o n s c o u l d cause acu te t o x i c i t y ; ( 3 ) metabol ism, r e p r o d u c t i o n , and growth may be reduced o r a l t e r e d i f o i l c o n c e n t r a t i o n s p e r s i s t near 1 ppm; ( 4 ) g rass shr imp r a p i d l y depura te accumul a ted pe t ro leum hydrocarbons when t h e y a re r e t u r n e d t o o i l - f r e e water; and ( 5 ) t h e t o x i c i t y o f o i l i s c o r r e l a t e d w i t h t h e r e l a t i v e p r o p o r t i o n o f t h e a romat i c f r a c t i o n p resen t .

Some i n v e s t i g a t o r s have e v a l u a t e d t h e e f f e c t s o f b i o c i d e s , such as t h o s e used t o remove f o u l i n g organisms f r o m c o o l i ng systems o f powerpl an ts ( g e n e r a l l y c h l o r i n e ) , on g rass shr imp. I n a r e v i e w by H a l l e t a l . (1979) i t was conc luded t h a t t h e d e t r i m e n t a l

e f f e c t s o f c h l o r i n a t i o n on g rass shr imp were neg l i g i b l e under normal powerpl an t opera t ions .

A d d i t i o n a l i n v e s t i g a t i o n s i n d i c a t e d t h a t P. p u g i o was l e s s s e n s i t i v e t h a n m y s i d - s h r i m p 0 d r i l l i n g muds b u t t h a t bo th were s e v e r a l o r d e r s o f magni tude more s e n s i t i v e t h a n f i s h e s (Conk1 i n e t a l . 1980); g rass shr imp were more s e n s i t i v e t h a n p i n f i s h (Laaodon rhomboides) t o a s i m u l a t e d i m e f f l u e n t c o n t a i n i n g phenol, s u l f i d e , ammonia, and some o t h e r components ( H a l l e t a l . 1978); and g r a s s shr imp were more s e n s i t i v e t h a n o t h e r c rus taceans t o i o n i z i n g r a d i a t i o n . R a d i a t i o n a f f e c t s m e t a b o l i c pathways i n v o l v e d i n t h e s y n t h e s i s of n o n - e s s e n t i a l amino ac ids used i n osmot ic r e g u l a t i o n (Engel e t a l . 1974).

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Overst reet , R.M. 1978. Mar i ne Maladies? Worms, germs, and o the r symbionts f rom t h e nor thern Gul f o f Mexico. M i s s i s s i p p i - A1 abama Sea Grant. Cons. MASGP-78-021. 140 PP.

Overst reet , R.M., and R.W. Heard. 1982. Food con ten ts o f s i x commercial f i s h e s f rom M i s s i s s i p p i Sound. Gul f Res. Rep. 7:137-149.

Overst reet , R.M., and E. Weidner. 1974. D i f f e r e n t i a t i o n o f m i c r o s p o r i d i a

spore- t a i 1s i n Inodosporus spraguei Gen. Sp. N. L. Paras i tenk .

Pomeroy, L.R., and R.G. Wiegert. 1981. The ecology o f a s a l t marsh. Spr inger-Ver lag, New York. 271 pp.

Rao, K.R., F.R. Fox, P. J. Conkl in, and A.C. Cantelmo. 1981. Comparative t o x i c o l o g y and pharmacology o f ch lorophenols : s t u d i e s on t h e grass shr imp Pal aemonetes pugio. Pages 37-72 i n t - . J. Ve rnbe rg e t a1 ., eds. 3 i o l o g i c a l mon i t o r i ng o f mar ine p o l l u t a n t s . Academi c Press, New York.

Rao, K.R., D.G. Doughtie, and P.J. Conk1 i n . 1982. Phys io l og i ca l and h i s t o p a t h o l o g i c a l e v a l u a t i o n o f d i th iocarbamate t o x i c i t y t o t h e grass shrimp, Pal aemonetes pugio. Pages 413-445 i n W.B. V e r n b e m t a1 . , eds. PhysTologica l mechanisms o f mar ine p o l 1 u t a n t t o x i c i t y . Academic Press, New York.

Sanders, H.O. 1972. T o x i c i t y of some i n s e c t i c i d e s t o four species o f ma1 acost racan crustaceans. U.S. Bur. Spor t F ish . W i l d l . Tech. Pap. 66: l -19.

Sand i fe r , P.A. 1973. E f fec ts o f temperature and s a l i n i t y on 1 a r v a l development of grass shrimp Pal aemonetes v u l g a r i s (Decapoda, Ca r i dea ) . U . . N a t l . Mar. F ish . Serv. F ish. B u l l . 71: 115-123.

Sand i fe r , P.A., and T.I.J. Smith. 1979. Poss ib l e s i g n i f i c a n c e of v a r i a t i o n i n t h e l a r v a l development o f p a l aemonid shrimp. J. Exp. Mar. B i 01 . Ecol . 39: 55-64.

Sas t ry , A.N., and S. L. .Vargo. 1977. V a r i a t i o n s i n t h e p h y s i o l o g i c a l responses of crustacean l a r v a e t o temperature. Pages 401-423 i n F.J. - Vernberg e t a1 . , eds . P h y s i o l o g i c a l responses of mar ine b i o t a t o p o l l u t a n t s . Academi c Press, New York.

Schimmel, S.C., and A.J. Wilson, J r . 1977. Acute t o x i c i t y o f Keponem t o f o u r e s t u a r i n e animals. Chesapeake Sci . 18:224-227.

Schimmel, S.C., J.M. P a t r i c k , Jr., and A.J. Wilson, J r . 1977. Acute t o x i c i t y t o and b i oconcen t ra t i on of endosu l f an by e s t u a r i n e animals. Pages 241-242 i n F.L. Mayer, and J.L. Hamelink, eds. Aquat ic t o x i c o l o g y and hazard eva lua t i on . ASTM STP 634. American S o c i e t y f o r Tes t i ng and M a t e r i a l s , P h i l a d e l - ph ia , Penn.

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I 10. CroiutfTa8h~orh Unlt No.

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Department o f B i o l o g i c a l Sciences U n i v e r s i t y o f Southern M i s s i s s i p p i Ha t t i esbu rg , MS 39406-5018

12 SPonsorIw Oaanlutlon Name and Addm8

Nat iona l Coastal Ecosystems Team U.S. Army Corps o f Engineers 13. T Y ~ . d Rewrt L hriod Connd

D i v i s i o n o f B i 01 og i ca l Services Waterways Experiment S t a t i o n F i s h and W i l d l i f e Serv i ce P.O. Box 631 U.S. Department o f I n t e r i o r Vicksburg, MS 39180 Washington , DC 20240

J. ROCIOI~H'S Accession NO.

I. Ra~or( Date

March 1985 6.

REPORT DOCUMENTATION I 1. "Em'" no. PAGE I B i o l . Rep. 82(11.35)*

1 s Supplementary Notn I

z

*U.S. Army Corps of Engineers Report No. TR EL-82-4 18. -met (Umlt: 200 words) I

I. nth and ~ubtnle

Species p r o f i l e s : 1 i f e h i s t o r i e s and environmental r e q u i r e ments o f coasta l f i s h e s and i n v e r t e b r a t e s (Gu l f o f Mexico)--

This species p r o f i l e summarizes much o f t h e l i t e r a t u r e pub l ished about t h e b i o l o g y o f grass shrimp, Palaemonetes spp. F i v e species (P. pug io , P. v u l g a r i s , P. in termedius , P. paludosus, and P. kadiakensis) a re common i n coasta l waters o f t h e no r the rn Gul f o f Mexico, a l t hough t h e l a s t two a re p r i m a r i l y f reshwater forms. The brackish-water species a re among t h e most abundant shal low-water ben th i c decopods i n e s t u a r i e s and p l a y impor tan t r o l e s as food f o r f i s h e s and as t r a n s p o r t e r s o f n u t r i e n t s among var ious t r o p h i c l e v e l s . They spawn from s p r i n g t o autumn and t h e growth o f p lank ton i c l a r v a e i s no rma l l y completed i n 7 t o 12 mol ts . Post la rvae o f 7-10 mm a re 1.5 t o 2 months old. The l i f e span o f grass shrimp i s 6 t o 13 months (maximum s i z e r a r e l y exceeds 50 mm). Palaemonetes spp. a r e eurythermal, euryha l ine , and a re r e l a t i v e l y t o l e r a n t t o hypoxia and a v a r i e t y o f p o l l u t a n t s . Grass shrimp feed on d e t r i t u s , epiphytes, and meiofauna. They tend t o concent ra te near underwater s t r u c t u r e s and p lan ts , e s p e c i a l l y i n dense stands o f underwater macrophytes.

I 17. DOcu- Analysis a. OescrigMn

Es tua r ies Growth Fishes Feeding

I b ldent10.n/0p.n-Endd Terms

Grass shrimp L i f e h i s t o r y Pal aemonetes spp. H a b i t a t requirements Temperature requirements Spawning

Unl i m i t ed

c COSATI F~eldlGmug

19 - a. Price

21. No. of Pages la Avellablllty Statement 19. Security Class (This Rc~orO

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