I.)CD Biological Report 82(11.102) TR EL,82-4

June 1989SN

Species Profiles: Life Histories and , 9 D'Environmental Requirements of Coastal Fishes : '

Iand Invertebrates (North and Mid-Atlantic)BLUE MUSSEL -

Coastal Ecology Group* Fish and Wildlife Service Waterways Experiment Station

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

S9906 08 6

0

Biological Report 82(11.102)

TR EL-82-4June 1989

Species Profiles: Life Histories and Environmental Requirementsof Coastal Fishes and Invertebrates (North and Mid-Atlantic)

BLUE MUSSEL

By

Roger I. E. NewellHorn Point Environmental Laboratories

University of MarylandBox 775

Cambridge, MD 21613

Project OfficerDavid Moran

U.S. Fish and Wildlife Ser"iceNational Wetlands Research Center

1010 Gause BoulvardSlidell, LA 70458

Performed for

Coastal Ecology GroupWaterways Experiment StationU.S. Army Corps of Engineers

Vicksburg, MS 39180

and

U.S. Department of the InteriorFish and Wildlife Service

Research and DevelopmentNational Wetlands Research Center

Washington, DC 20240

PREFACE

This species prefile is one of a series on coastal aquatic organisms, principally fish, of sport, commercial,or ecological importance. The profiles are designed to provide coastal managers, engineers, and biologists witha brief comprehensive sketch of the biological characteristics and environmental requirements of the species andto describe how populations of the species may be expected to react to environmental changes caused by coastaldevelopment. Each profile has sections on taxonomy, life history, ecological role, environmental requirements,and economic importance, if applicable. A three-ring binder is used for this series so that new profiles can beadded as they are prepared. This project is jointly planned and financed by the U.S. Army Corps of Engineersand the U.S. Fish and Wildlife Service.

Suggestions or questions regarding this report should be directed to one of the following addresses.

Information Transfer SpecialistNational Wetlands Research CenterU.S. Fish and Wildlife ServiceNASA-Slidell Computer Complex1010 Gause BoulevardSlidell, LA 70458

or

U.S. Army Engineer Waterways Experiment StationAttention: WESER-CPost Office Box 631Vicksburg, MS 39180

lio

[A . > . .~~

.. . ii II I II IIII

CONVERSION TA BLE

Metric to U.S. Custoinar\

Mutpy. () u

millimeters (mm 0.03937 p. ie'

centimeters (cm) (0.337 inches

meters in) 3.281 let

meters (01) 0.5468 fathois

kilometers (km) 0.62' 4 siaite .

kilometers (kin) 0.5396 n,uiical rniic¢e

square meters (m 2 10.76 Square eie

square kilometers (k i 110.3 s1iquare nfle

hectares (ha) 2.471 acres

liters () 0.26112 zalins

cubic meters (n-3 35.31 cLIbic feet

cubic meters (m3 ) 0.0008110 acre-feet

milligrams (mg) 0.00003527 ounces

grams (g) 0.03527 ounces

kilograms (kg) 2.205 poundsmetric tons (t) 2205.0 pounds

metric tons (t) 1.102 short tons

kilocalories (kcal) 3.968 British thermal units

Celsius degrees CC) 1.8(°C)+32 Fahrenheit aegrees

U.S. Customary to Metric

inches 25.40 millimeters

inches 2.54 centimeters

feet (ft) 0.3048 meters

fathoms 1.829

statute miles (mi) 1.609 ., ", . , s

nautical miles (nmi) 1.852 K rs

square feet (ft2

) 0.0929 square meters

square miles (mi 2l 2.590 square kilometers

acres 0.4047 hectares

gallons (gal) 3.785 liters

cubic feet (ft) 0.02831 cubic meters

acre-feet 1233.0 cubic meters

ounces (oz) 28350.0 milligramsounces (oz) 28.35 grams

pounds (1h) 0.4536 kilograms

Pounds (Ib" 0.00045 metreic tons

short tons (ton) C 072 metric tons

British thermal units (Bhud 0.2520 kilocalories

Fahrenheit degrees c F) 0.5556 ('F-32) Celsius degrees

CONTENTS

Pag~e

PREFACE............................ .. .. ........ . . ... .. .. .. .. .. . . ...CONVERSION TABLE..................... . . . ..... . .. . .. .. .. .. .. ... vACKNOWLEDGMENTS .. ...... ........ ........ .... ....... v

NOMENCLATURE. TAXONOMY. AND RANGE. .. ..... ........ ....... IMORPHOLOGY AND IDENTIFICATION........ .... . ... . .. . .. .. .. .. .. ....REASON FOR INCLUSION IN SERIES .. ... ........ ...............

LIFE HISTORYT.. .. .. ..... ........ .................... 4

Reproductive Physiology ... .. .. ........ ........ ........ .... 4

Spawning .. ... ....... ........ ........ ........ .......

Gametes and Fecundity.. .. .. .. ........ ........ ........ .... 7Reproductive Strategy .. .. .. ....... ........ ....... ......... 7Larval Development and Behavior .. ... ........ ........ ......... 7Settlement and Juvenile Development. .... ....... ........ ........ 9Adults. .. ........ ....... ........ ........ ......... 9

GROWTH CHARACTERISTICS .. ........ ........ ........ .... 9THE FISHERY .. .. .. ........ ........ ....... ........ .... 1

Commercial Shellfisheries. .. ....... ....... ........ ........ I IPopulation Dynamics .. ..... ........ ........ ........ .... 13

ECOLOGYl.. .. .. ........ ........ ....... ........ ..... 13Feeding and Nutrition. .. .... ........ ........ ........ .... 13Predators .. ... ........ ....... ........ ........ ..... 15Parasites and Diseases. .. ..... ........ ........ ........ ... 15Competitors. .. ................................. 15

ENVIRONMENTAL REQUIREMENTS . .. ...... ................... 16Temperature................... .. . . ...... . ... .. .. .. .. . ..........Salinity .. .. ........ ....... ....... ...... ........ ... 17

Substrate and Current. .. ...... ....... ........ ........ ... 18Oxygen. .. .... ........ ........ ........ ........ ... 18Anthropogenic Contaminants. .. ... ........ ........ ........... 19

LITERATURE CITED. .. ........ ....... ........ ......... 21

ACKNOWLEDGMENTS

The blue mussel, Mytilus edulis, is often considered to be the "white rat" of the marineinvertebrate zoologist, due to its widespread distribution and the ease with which it can becollected and maintained in the laboratory. As a consequence it has been the subject of intensescientific investigation over the last two decades. This wealth of information has made my task ofassembling this brief review of the biology of the blue mussel on the Atlantic coast of the UnitedStates particularly challenging. Therefore, within the text I have referenced the major reviews ofvarious aspects of the biology of the blue mussel where interested readers can obtain more detailedinformation. In particular, I draw attention to the book Marine Mussels, edited by Bayne (1976a),which provides a comprehensive treatment of many aspects of the biology of Mvtilus edulis.

I am grateful to Dr. Thomas J. Hilbish, Dr. Victor S. Kennedy, Mr. Carter Newell, and Dr. RayJ. Thompson for reviewing a draft of this manuscript. Debbie Kennedy drew the illustration of theblue mussel shell.

vi

Byssal and Pedal Muscle

Relactor PosteorScar - d cto

Hinge Addctor

L Igamrne nt M~~. v- u Ms clIe

~................... i,'Urnbo

DoralPosterior

* ,Ventral

Figurc I. Internal and external characteristics of the blue mussel Mylilus edulis.

BLUE MUSSEL

NOMENCLATURE, TAXONOMY, AND from Labrador to Cape Hatteras, NorthRANGE Carolina (Wells and Gray 1960), and it is

common throughout the North Atlantic andScientific name ..... mytilus edulis Linne 1758 Mid-Atlantic Regions (Figures 2 and 3). It

(Abbott 1975) is most common in the littoral to sublittoralPreferred common name .......... blue mussel zones (<99 m) of oceanic and polyhaline to

(Figure I) mesohaline estuarine environments; however,Other common names ...... mussel, sea mussel it has been found in deeper and coolerClass ..................... Bivalvia (Pelecypoda) waters (100 to 499 m) that enable it toOrder ................................ Mytiloida penetrate as far south as Charleston, SouthFamily ................................. Mytilidea Carolina (Theroux and Wigley 1983).

Geographic range: The blue mussel is a widelydistributed boreo-temperate species occurring MORPHOLOGY AND IDENTIFICATIONin the Arctic, North Pacific, and NorthAtlantic Oceans (Seed 1976). On the east The shape of the blue mussel shell iscoast of North America, its range extends roughly an elongate triangle; the longest dim-O1

CANADA>?MAINE

~, K> ~ ty

LU

z

ATLANTIC OCEAN

Coastal distribution

MILESI0 0 100

0 1.0 100

K ILOME T ERS

Figure 2. North Atlantic distribution of (the blue mussel.

--- '- ',R MASS _T

NEW YORK X RI

CONN TICUT

- /NEW YORK

NEW'JERSEY

PENNSYLVANIA

'N PHILADELPHIA

Q

-~ ATLANTIC OCEANMARYLAND . \ w

_ BALTIMORE ,

WASHINGTON, D.C <

VIRGINIA m.

' Coastal distribution

MILESL B - . u N o ,,o o

}- 0 T0 10

KI LOME T E RS

NOTH CAROLINANORTH CAROLINACAPE

HATTERAS

Figure 3. Mid-rA, antic distribution of the blue mussel.

3

ension (,a. "-10 cm) is along an anterior- Blue mussel larvae can be identified onposterior axis from the narrow beaks of the the basis of both their shell morphometricsumbo to the broad posterior shell margin and the position of the ligament (for reviewFigure I ). The shell has a sculpture of fine and photomicrographs, see Bayne 1976b). More

concentric lines and is dark blue to black in positive larval identification can be obtainedcolor. [he entire outer surface of the shell is by scanning electron microscopic examination,:o'ered b' a shin proteinaceous membrane, of the dentition on the hinge, which isthe periostracum. As this protective distinctly different from that of other bivalveperiostracum becomes abraded, ?specially larvae (Lutz and Hidu 1979).toward the umbo. the outer, colored, prismaticcal,:itic lay er sometimes becomes eroded, The only species within the North andexposing the white, inner, prismatic, aragonitic Mid-Atlantic Region that can easily belaver (Carter 1980). Within any blue mussel mistaken for the blue mussel is the horsepopulation, a few individuals haxe shells that mussel, Modiolus modiolus. Unlike the blueare light brown or ha e stripes of different mussel, the horse mussel has umbonal beaks,shades of browxn. The interior of the shell has which are not at the apex of the shell buta border of dark blue to violet surrounding the displaced to one side, and by its larger adultpearly white nacreous layer, size (10-15 cm) and heavier and more eroded

shell. Juvenile horse mussels can bedistinguished from blue mussels by periostracal

Blue mussels are semi-sessile epibenthic "hairs" on the posterior margin of the shell.bivalxes that are anchored to a secure The horse mussel is usually found in deepersubstrate, or attached to other mussels, with oceanic water than the blue mussel and doesbyssus threads secreted from glands in the not penetrate estuaries. The shells of otheranimal's foot. \When the valves are closed, the species of mussels, such as the ribbed mussel,bssus threads pass through a small notch, the Geukensia demissa, and the hooked mussel,pedal gape, in the middle of the ventral Brachidontus recurvus, have numerous ridgesjunction of the twko valves. The blue mussel radiating from the umbo towards the posteriorcan achie,,e a limited degree of movement by shell margin that clearly distinguish them fromsecreting new threads and adjusting the the smooth shell of the blue mussel.lengths of others. This mobility enables theanimal to reposition itself in relation to watercurrents (Yonge 1976), to avoid getting REASON FOR INCLUSION TN SERIESsmothered by accreting sediments (Seed 1976),and to move toward the outer edge of mussel The blue mussel is a common and oftenclumps (Harger 1968). abundant species in the coastal waters of the

North and Mid-Atlantic Regions, where it is anThe interior anatomy has distinctive important prey item for many animals.

characteristics. The posterior adductor muscle Unfortunately, it is precisely these waters thatis much larger than the anterior adductor are affected most by the increasedmuscle. In empty shells, the scars of the urbanization of the Northeastern United Statesposterior adductor muscle and retractor and the disposal of industrial wastes. Inmuscles (both posterior pedal and byssal addition to its ecological importance, the blue[Yonge 197611 are clearly visible (Figure I). mussel is currently the basis of a resurgentIn the center of the visceral mass is the fishery based on wild stocks and a developingdarkly pigmented foot, which can be extended aquaculture industry throughout the Northto secrete a new byssus thread. The mantle, Atlantic Region.which extends from either side of the visceralmass. is attached to the entire periphery ofboth valves of the shell. New shell growth is LIFE HISTORYinitiated from the mantle margin (Wilbur andSaleuddin 1983). In two places posteriorly, the Reproductive Physiologymantle is modified to form an inhalant andexhalent siphonal aperture to direct feeding The blue mussel is diecious, though rarecurrents into and out from the mantle cavity, instances of hermaphroditism have been

4

repotted (Seed 1976). Mussels generally synchrony is essential for an oviparous speciesprodu2e gametes and are ready to spawn by and ensures that larvae are in the water atthe time the\ are one Near old, however, when the optimum time for their growth and survivaladerse ens ironmental conditions (e.g., (Sastry 1979).prolonged periods of exposure to air) cause aslow rat- of grow th, sexual maturity is The timing of the various components ofsometimes not attained until the second year. the reproductive cycle differs greatly between

various blue mussel populations within theAlthough the gonad is situated within the North Atlantic and Mid-Atlantic Regions

isceral mass it extends during the (Figure 4: Newell et al. 1982). Newell et al.reproductive period into the mantle, which also (1982) concluded that latitude and waterbecomes swollen with gametes. temperature were not as important as foodPre\ itellogenesis (i.e. formation of oogonia and availability in governing the reproductive cyclespermatogonia) occurs during the period from of the blue mussel along the east coast of thewinter through early spring when food United States. Thus, it is impossible toa'ailability is generally low and feeding predict the timing of the reproductive cycleactivit) is further depressed by low water for any particular population. Fortemperatures. Energy for gametogenesis during environments in which variations in physicalthis period is supplied from nutrient reserves factors are not large -- especially those thatof glycogen, which are sequestered during the influence patterns of phytoplankton productionpost-spaning period and stored in the - it is likely that the reproductive cycle forNesicular cells specialized cells in tue the blue mussel is probably rather constantconnective tissue of the mantle (reviewed by from year to year (Newell et al. 1982). InGabhott 1983). The blue mussel sequesters a habitats where annual variations inseparate nutrient reserve in the digestive glan' environmental factors are large, such as into supply the energy that sustains metabolic estuaries with annually variable freshwaterenergy demands during the period of reduced inputs and year to year variations in waterfood intake in the winter. Vitellogenesis, the temperature, the reproductive cycle of Mytilusfinal stage of gametogenesis when the edulis can be expected to vary (Thompsonspermatocytes and oocytes are formed, usually 1979,1984a; Lowe et al. 1982).occurs oxer a comparatively short period of afew weeks in the late spring, during which the Spawningnucleus enlarges and lipids are synthesized andstored in the egg yolk (for review see Sastry When sperm and eggs are fully ripe they1979). Energy for .itellogenesis is supplied are released from the follicles in each gonadfrom the remaining glycogen reserves, from into a series of genital canals that graduallylipid reserves stored in adipogranular cells in combine into a common gonoduct that opensthe mantle, and from freshly ingested food on the genital papilla (Bayne 1976b). Eggs andmaterial (Gabbott 19831. The ripe gametes are sperm are liberated via the exhalent siphonthen ready to be spawned: if their release is directly into the water column, wheredelayed, they degenerate and are resorbed by fertilization occurs. About 10,000 spermatozoahemoc> tes. are shed for each ovum spawned (Thompson

1979).Gametogenesis. spawning, and nutrient

storage are linked in an integral process The exact factors that stimulate the firsttermed the reproductive cycle. This cycle in mussels within a population to spawn areany blue mussel population is the result of a unknown. However, a prerequisite is thecomplex balance between exogenous factors presence of fully-ripe gametes thit are readysuch as food availability, temperature, salinity, to be liberated. If the gametes are ripe,and duration of exposure to air and spawning may be stimulated by a slightendogenous factors such as nutrient reserves, increase in water temperature or change inhormonal cycle, and genotype (Seed 1976; salinity, mechanical disturbance as a result ofSastry 1979). Interaction between these wave action, desiccation, or even highfactors ensures the synchrony of gamete concentrations of phytoplankton in the waterdevelopment within the population. Such (Seed 1976). Males generally start to spawn

* I5

DE

0 ii

4A

Figure 4. Mean reproductive condition of male and female blue mussels through the breedingseason, measured at times designated by solid circles, from seven sites on the east coast of theUnited States. The reproductive condition varies between 1.0 for a fully ripe mussel and 0.0 forone wkith no discernible gametes. ME = Damariscotta River, Maine, NIH = Newcastle, NewHampshire, MIA =Cape Cod Canal, Massachusetts, RI =Narragansett Bay, Rhode Island; SB =StonyBrook, New York; SHIN = Shinnecock, New York; DE =Broadkill Inlet, Delaware (from Newel: et al.1982).

first; the presence of sperm in the water Newell et al. 1982; Rodhouse et al. 1984).then stimulates the females to cease filtering Such spawnings may take the form of mass

(Newell and Thompson 1984) and start s:-lv.nings in which an individual musselspawning. This synchronous spawning ensures liberates most of its gametes over a shortthat the sperm and eggs are in the water period. Such spawning is followed by acolumn concurrently. refractory period, during which further oocytes

and spermatocytes are developed for the nextspawning. In other situations, no large

At some localities, a particular set of numbers of gametes in any one mussel ripenenvironmental conditions ena[Iles the blue simu~taneously; instead, gametes are continuallymussel to repeatedly spawn (Lowe et al. 1982; ripening and are liber-'ted in a "dribble" spawn.

6

Fertilization requires dribble-spawning from a food, or pollutants) during gametogenesis andnumber of individuals within the population. vitellogenesis. Such reduction in larval

viability is most likely due to less lipidGametes and Fecundity reserves being apportioned to each egg. If the

adult mussels are stressed during theThe eggs are spherical and 68-70 jam in reproductively quiescent period or during the

diameter; each possesses a vitelline coat 0.5-1.0 early stages of gametogenesis, the normalpm thick, and contains numerous lipid droplets gametogenic cycle is not initiated (Bayne et al.and yolk granules (for review see Bayne 1982). Mussels that are stressed when ripe1976b). Accurate measurements of fecundity gametes are present begin resorbing theare difficult to obtain due to the experimental gametes (Bayne et al. 1982). Thus, adifficulties of assessing an individual female's perturbation of an environmental factor canoutput over the entire breeding period, reduce the reproductive capacity of a blueEstimates obtained by inducing females to mussel population, even though it occursspawn in the laboratory suggest that a large outside of the normal reproductive season andadult mussel (4-5 cm long) weighing Io does not appear to have any adverse effects(tissue dry weight) may liberate about 8 x 10 on the adult.eggs (Bayne et al. 1978; Thompson 1979).More accurate fecundity estimates were Larval Development and Behaviorobtained by Thompson (1979) from the mantleweight loss of mussels at three locations on The stages of larval development andthe east coast of North America, including their durations are summarized in Table 1. ItStony Brook, Long Island, which indicate total must be emphasized that the larval stage mayfecundities per gram dry tissue weight of I x last anywhere from 15 to 35 days and that the107 eggs for females and 1.1 x 1011 sperm for duration is dependent on prevailingmales. environmental conditions. Larvae of blue

mussels from Connecticut developed normallySpermatozoa swimming freely in the water only within the temperature range of 15-20 °C;

column react on contact with the egg by at 15 °C they developed normally in salinitiesextruding an acrosome filament (Bayne 1976b) ranging from 15 to 35 ppt, whereas at 20 °Cthat enables the sperm to penetrate the they could only develop normally between 20vitelline coat and initiate meiosis. At 18 °C and 35 ppt (Hrs-Brenko and Calabrese 1969).the eggs hatch about 5 h after fertilization to Bayne (1965) reported that the trochophoreproduce a ciliated embryo. could develop successfully only in a salinity of

30-40 ppt and at temperatures of 8-18 °C, andReproductive Strategy that within this temperature range, the

development rates were fastest at the highestThe large number and small size of eggs temperatures. Larvae from an oceanic blue

produced by the blue mussel are typical of the mussel population grew fastest at 30-32 pptplanktotrophic reproductive strategy in which and did not grow well at salinities below 24output is maximized but nutrient investment ppt (Bayne 1965). In contrast, larvae rearedper egg is small (for review see Bayne 1976b). from blue mussels collected from a moreThis strategy is generally considered to aid estuarine population continued to develop indispersal as it al' -.. musels to produce the salinities as low as 14 ppt. Innes and Haleymaximum numhe, f larvae which require a (1977) reported that in blue mussels, theprolonged p, _! development period, expression of population and family differencesHow'ver, such a ,r,tey produces an egg with in growth rate depended on the salinity atthe barest minimc,-. c nutrient reserves to which the larvae were reared. Theyenable the lirva t .jevelop sufficiently to interpreted these results to indicate that therestart feeding cr i lanKton. was a significant genotype-environment

interaction during larval development.Laboratory experiments of Bayne et al.

(1975, 1978) demonstrated that the viability of These data on the influence ofmussel larvae is compromised if the parent is temperature and salinity on larval growthstressed (e.g., by high temperature, insufficient demonstrate that larvae are clearly influenced

7

Table 1. Life stages and characteristics of the blue mussel (Bayne 1976b).

Stage Size (length) Age and characteristics

Fertilized egg 68-70 pm 0-5 h Non motile.Trochophore 70-110 pm 5-24 h Ciliated and motile.Veliger Up to 35 days; Feeds and

swims with ciliated velum.a) Prodissoconch 1 110- Straight-hinged shell.b) Prodissoconch II -260 pm Umbo on shell.c) Eyed Larvae 220-260 pm Development of pigmented 'eye spots'.d) Pediveliger 260 pm Development of foot.

Plantigrade 0.26-1.5 mm Up to 6 months; temporarily attachedto filamentous substrates.

Juvenile Up to 2 years; sexually immature.Adult Up to 100 mm Up to 20 years; sexually mature.

by the environmental regime of the parent, larval shell. The later stages of veligerThere is some evidence to suggest that development are characterized by the formationenvironmental variables interact to affect of a pair of photosensitive pigmented eye spotssurvival and growth (Bayne 1983). Also, and an elongated foot with a byssal gland.tolerance to environmental variation is lowerin the earlier than later larval stages, andlower in the larvae than the adult. Bayne Once the velum is fully developed, the(1976b) suggested that the environmental beating of the large marginal cilia on therequirements for embryonic development are a velum can pull the larva spirally upwardslimiting factor regulating the distribution of through the water column. If the larvaestuarine blue mussel populations. withdraws the velum into the shell or reduces

the rate of ciliary beating, it sinks. TheThe first developmental stage is the veliger is carried passively with ocean and

ciliated embryo which differentiates within estuarine currents because it has little abilityabout 24 h of fertilization to form the to swim horizontally. However, the larvae oftrochophore. Although the trochophore is many bivalves (Mileikovsky 1973), includingmotile at this stage, it is non-feeding and thus those of Mvtilus e-ulis (Bayne 1963, 1964),still relies on the yolk for nutrient. The alter their swimming behavior in response toveliger stage is characterized by the certain key environmental stimuli such asdevelopment of a functicnal mouth and salinity, gravity, pressure, and light.alimentary system, together with a group of Generally, the responses by younger larvae tocilia at the anterio. end that enlarge to form environmental factors keeps them in surfacethe velum. The ciliated velum serves both to waters. Older larvae tend to sink to thepropel the larva and to filter food particles, bottom in response to reduced salinity butespecially nanoplankton. A shell gland swim upward in response to increasing salinity.secretes a thin transparent shell, producing the Such behavioral responses have generally beencharacteristic "straight hinge" of the interpreted as indicating that larvae ofprodissoconch I shell. The veliger continues estuarine species respond to the reduction into develop and eventually the cells of the salinity that occurs in estuaries on the ebbmantle assume their adult role in shell tide by dropping out of the net seaward-formation with the initial production of the moving water mass. Once the tide turns, theprodissoconch II shell, characterized by the bottom salinity increases. Because there is adevelopment of a pronounced umbo on the net upstream flow in the bottom waters of

8

estuaries, any larvae entrained in this higher much wave splash (Seed 1976). In somesalinity water mass are carried up the estuary localities the penetration of the blue mussel(Wrod and Hargis 1971). into the sub-littoral zone is limited by the

presence of various predators (see PredatorsSettlement and Juvenile Develooment section). A primary requisite for the

establishment of a blue mussel population is aWhen the pediveliger is fully developed, it surface for attachment of the byssus threads;

extends its foot, makes contact with the however, the substrate may vary from largesubstrate, and searches for a filamentous boulders to pebbles or, very frequently, othermaterial, such as algae and hydroids (Bayne mussel shells. In sheltered environments, large1976b). On contact with such a substrate the aggregations of mussels sometimes form denselarva first uses its foot to crawl over the beds that provide shelter and food (in thesurface or attach loosely (Bayne 1976b). If form of copious amounts of biodeposits) for athe substrate is suitable, the larva variety of other invertebrates. In both thesemetamorphoses into the juvenile form, termed sheltered environments and exposed shores,a plantigrade, and attaches with byssus threads blue mussel clumps sometimes become so thick(primary settlement). The plantigrade remains that relatively few individuals are attached toattached to filamentous substrates until it the firm substrate. In such situations, stormsreaches a length of about 1-1.5 mm. It has occasionally wash away large sections of thebeer suggested that this primary settlement bed (for review see Seed 1976).enables the young mussels to grow in anenvironment free from the competition for GROWTH CHARACTERISTICSfood and space that can occur in dense musselbeds (Thorson 1957). Blue mussel larvae produced from adults

collected from the North Sea and maintainedAfter growing to about 1.5 mm shell at 12 °C grew at an average daily rate of 7.5

length the piantigrades release themselves from urm which was reduced to 3.3 pm when thethe filamentous substrate and reenter the amount of food was decreased by 80% (Sprungplankton. The extension of the foot and the 1984). Rate of larval growth increasedattached byssal threads causes the plantigrades progressively at temperatures above 5 °C to ato be passively carried by currents in the maximum at about 16 °C. Growth was notbottom waters (Bayne 1976b). When the reduced by temperatures of up to 20 °C (Bayneplantigrades contact adult mussels they are 1965); for larvae from parents collected from astimulated to produce new byssus threads and low temperature environment, increases inattach themselves to the substrate, or directly temperature above 16 °C reduced growth ratesonto the shells of other mussels (Bayne 1976b). (Bayne 1965). However, as discussed in both

the Larval Development and the EnvironmentalThis primary settlement and growth Requirements sections, the influence of

period of the plantigrades, followed by their temperature is not fixed but varies amongsecondary recruitment into the adult populations as a balance between geneticpopulation, makes it difficult to predict exactly composition and previous thermal history.when recruitment to any given musselpopulation will occur (Seed 1976). When this The size of an adult mussel at any yearuncertainty is coupled with the wide variation during its life can be assessed from the annualin the time of spawning in different blue growth bands that are exposed when the shellmussel populations in the North and Mid- is sectioned along the antero-posterior axisAtlantic Regions, it becomes apparent that (Lutz 1976). These age-length data can berecruitment can occur at almost any time of used to construct growth curves to which anthe year. exponential equation, such as the generally

accepted Von Bertalanffy growth model, can beAdults fitted. Such growth data are available for

natural mussel populations from Stony Brook,The blue mussel lives in habitats that Long Island, New York (Rodhouse et al. 1986)

range from flat intertidal shores that drain and Bellevue, Newfoundland (Thompson 1984b).slowly to vertical surfaces that are subject to These data (Figure 5) illustrate that the

09

10 O

8o •

Eo/

v 6 0000

00Oo./

4 .

2

0 2

0 2 4 6 8 10 12

Age (years)

Figure 5. Shell length as a function of age, with the Von Bertalanffy growth model fitted,for blue mussels from New York (open circles; data from Rodhouse et al. 1986) and fromNewfoundland (solid circles; data from Thompson 1984b).

southern population has a much faster growth he reported that the maximum dry tissuerate for the first two years; however, the biomass (1.07 kg dry tissue weight" m - 2 ) of amaximum age and size attained by mussels is population of blue mussels in Newfoundlandonly 4-5 years and 5.5 cm in the southern developed in June, before a large proportion ofpopulation but at least 11-12 years and 9.5 cm the production was spawned as gametes. Thisin the northern population. Such a dependence estimate is similar to the value of 1.5 • kg m -2

of growth rate on latitude may possibly be a recorded by Nixon et al. (1971) for a musselconsequence of the shorter feeding seasons for population in Narragansett Bay, Rhode Island.northern populations; the increased longevity However, great care must be taken to ensureof northern mussels may be a result of reduced that when shell growth rates of blue musselsmetabolism (Seed 1976). On the east coast of are used to estimate tissue growth that therethe United States the highest recorded growth is no seasonal variatioti in the allometricrates of as much as 5 cm per year (or up to relationship between shell growth and tissue25 times that in natural populations) were growth (Hilbish 1986). Frequently in the bluemeasured in mussels growing continuously mussel, as well as in other species of molluscs,submerged in areas of high food availability, the growth of new shell may besuch as those in raft-based mariculture disproportionately faster than that of tissue;operations (lncze and Lutz 1980). inaccuracies in production estimates may

result. Hilbish (1986) reported that shellAlthough shell growth rates are relatively growth of small blue mussels (<2 cm shell

easy and convenient to measure, Thompson length) from Long Island Sound, New York,(1984b) noted that they are biologically less was greatest from April to June, whereasrelevant than estimates of tissue production; tissue growth was greatest in June and July.

10

Thompson (1984b) demonstrated that in detailed analysis of the technical and financialblue mussels from Nexfoundland, the majority aspects of blue mussel mariculture (Lutz 1980)of energy was initiall, partitioned into shell demonstrated that Mytilus edulis is a goodand somatic growth. As the animal grew candidate for successful shellfish culture inolder, progressively larger proportions of the New England. It grows faster than mostproduction was germinal: in the largest traditional shellfish species, yields a highermussels. 94% of the assimilated energy was ratio of meat to total weight, and isused for the production of gametes. Rodhouse nutritionally superior. However, because theet al. (1986) demonstrated that fecundity was market is still relatively limited, intensivehigher in geneticall% heterozygous than in mariculture of the blue mussel is only ahomoz.gous blue mussels sharing the same marginal economic proposition (Clifton 1980).environment.

Currently the economics of the fisheryfor wild stocks and part-managed bottom

THE FISHERY culture are much better because per-unitproduction costs are only about one third

Commercial Shellfisheries those for off-bottom mariculture (Clifton 1980).Although the fishery for wild stocks in New

In the United States, the blue mussel has England was thought to be approaching ahistorically not been considered to be as maximum sustainable yield (Clifton 1980), thedelectable as oysters, scallops, or various discovery of new inshore and offshore beds inspecies of clams (Clifton 1980); however, due Maine and Massachusetts, as well as theto intensive marketing efforts over the last development of certain management practices,decade it is becoming an increasingly popular such as thinning wild stocks and moving stocksitem on seafood restaurant menus throughout between areas to improve meat quality andthe United States. In Canada and Europe the yields, has enabled annual harvests to increaseblue mussel is considered to be a quality with demand (Table 2). Blue mussels areseafood product and in Spain, France, Iolland, generally gathered in the larger commercialand Italy, it forms the basis of an extensive operations by dredging and sorting aboard shipcommercial mariculture industry (for review see using a mechanical washer-grader; in smallerMason 1976). operations they may be harvested in shallow

water by raking or pitchforking them intoThe blue mussel has a number of small boats before they are transferred to a

characteristics that make it ideal for intensive larger vessel for mechanical cleaning andcommercial mariculture. The high fecundity sorting (Chalfant et al. 1980).and recruitment of natural blue musselpopulations allow small mussels to be collected The blue mussel harvest on the east coastfrom natural seed beds (incze and Lutz 1980). of the United States increased gradually duringThe larvae can also be collected directly, at the decade before 1975 and then rapidly, tometamorphosis, on fibrous spat collectors that more than 1,400 t of meats, in the late 1970'sprovide the filamentous substrate needed for (Clifton 1980). This harvest was the first timeprimary settlement (Mason 1976). Both of the high level of the early 1940's was reached,these attributes eliminate the need for when the mussel was widely exploited duringexpensive hatchery production of seed, as World War 11 (Miller 1980). Currently, most ofrequired in the oyster mariculture industry of the commercial landings of the blue mussel onthe west coast of the United States. The the east coast of the United States come fromability of mussels to attach to surfaces, such Maine and Massachusetts, and smaller (annuallyas ropes, makes it possible to cultivate them variable) amounts from New York, Rhodeeasily 'off-bottom' and not in more complex Island, and New Jersey (Table 2). The 1986and expensive suspended racks or cages. This total harvest of 3,909 t was more than twicetrait is an important benefit to commercial as large as that in 1982 and was worth nearlymariculture because it eliminates both self- $4 million. The lower average unit value offouling from the biodeposits (feces and mussels from Maine, compared with that inpseudofeces) and the incidence of pearls, and other states, is partly due to the fact that areduces mortality from benthic predators. A substantial portion of Maine's harvest comes

I* 11

Table 2. Annual blue mussel landings (metric tons of wet meat weight) and dockside value of thelandings (thousands of dollars) for mussel producing states on the east coast of the United States.Years with no commercial harvest are designated by NH. Data provided by National MarineFisheries Service.

State and item 1979 1980 1981 1982 1983 1984 1985 1986

MaineMetric tons 1,361 1,058 1,427 1,315 2,018 2,596 2,762 2,831Thousands of dollars 716 546 851 835 1,408 1,998 2,079 2,307

MassachusettsMetric tons 88 185 296 409 334 328 872 993Thousands of dollars 107 237 444 511 510 443 1,296 1,441

Rhode IslandMetric tons 26 45 15 109 NH NH 58 73Thousands of dollars 43 29 26 504 258 175

New YorkMetric tons 62 90 51 52 52 67 70 12Thousands of dollars 72 112 82 81 98 117 118 27

New JerseyMetric tons NH NH 0,14 0.05 0.41 2.7 NH NHThousands of dollars 0.02 0.08 0.39 4.2

TotalsMetric tons 1,537 1,378 1,789.14 1,885.05 2,404.41 2,993.7 3,762 3,909Thousands of dollars 938 924 1403.02 1,931.08 2,016.39 2,562.2 3,751 3,950

from unmanaged wild blue mussel beds. The important, apart from the lack of publiclower meat yield and the high incidence of awareness of the blue mussel, is that largepearls makes these blue mussels generally Pumbers of blue mussel beds near populationinferior to those produced in adjacent managed centers are closed because of high coliformbottom culture operations. Such differences in counts (Chalfant et al. 1980). In addition,quality are mainly due to differences in growth there are public concerns about Paralyticrate, with mussels in natural beds taking over Shellfish Poisoning (PSP), which sometimes7 years to attain market size, compared to 2- results in neurotoxic symptoms and even death5 years in managed bottom culture. The higher in humans (Halstead 1965). This poisoningaverage value of the wild mussels from results from the bioaccumulation by blueMassachusetts and Rhode Island reflects mussels (in common with other suspensiondifferences in the environmental conditions in feeding bivalves, such as scallops and clams) ofthese two states that leads to faster growth toxins produced by dinoflagellate algae,rates and hence improved meat quality and especially of the genus Gonvaulax (for aoverall appearance. review see Yentsch and lncze 1980). These

phytoplankton species, though presentThere is recreational hand gathering of throughout the year, undergo periodic blooms

blue mussels in all states north of New Jersey during the warmer months, when their numbers(Miller 1980); however, little information is increase rapidly. It is only in such situationsavailable on the size of this fishery because it that the bivalves can accumulate enough toxins's subject to much less control (by local to cause PSP. In Maine, New Hampshire, andordinances) than are other sport shellfisheries Massachusetts, state-operated PSP programs(e.g., for softshell and hard clams). Perhaps use sensitive bioassays to monitor toxin levelsone reason the sport fishery is not more in the blue mussel at numerous designated

12

sampling stations. In this way the mussel beds suppose that non-refractory organic matter iscan be closed to harvest before toxin levels not digested in the same way as living cellsbecome dangerous (Yentsch and lncze 1980). (Widdows et al. 1979a). The direct utilization

of refractory detritus varies among species ofPopulation Dvnamics bivalves, but is generally low (Newell and

Langdon 1986; Kreeger et al. 1988). AttachedA large percentage of the eggs spawned bacteria are a major source of protein in

by the blue mussel may not get fertilized and detritus (Crosby 1987), and there is evidencelarge percentages (up to 99) of the larvae that that adult blue mussels can digest bacteriadevelop may be eaten prior to metamorphosis (Birbeck and McHenery 1982).(Bavne 1976b). Despite this high attrition,blue mussel larvae sometimes are the dominant Both larvae and adults use cilia tocomponent of the zooplankton for short remove food particles from suspension. Theperiods. Fish and Johnson (1937) reported cilia generate a pattern of water flow thatlarval abundances of more than 25 x 103 m - 3 creates complex shear velocities which resultduring August in the Bay of Fundy. in small-scale regions of high and low

pressure. In the low pressure regions,The blue mussel has a complex particles can be entrained in surface water

recruitment pattern of primary settlement away currents generated by other cilia, which thenfrom the a'.ult population, followed by almost move the particles to oral food groovescontinual gradual recruitment of the (Jorgensen 1981; Jorgensen et al. 1984). Theplantigrades Into the adult population (Seed particles, entrapped in mucus secreted within1976). This behavior makes it difficult to these food groves, are then transported to theassess the mortality patterns of the juvenile mouth.stages in a population because it iscomplicated by immigration and emigration. In larvae, the ciliated velum is used asThus, the number of plantigrades in a both a swimming and feeding organ (Baynepopulation is seasonally and annually variable 1983). Phytoplankton cells ingested by bivalvebut can range from between 20 to 200 cm - larvae must be small (Bayne 1983) because of(Seed 1976). the physical constraints of the larval

esophagus, which is about 10 pm wide. InThe mortality pattern of adult blue rearing studies the fastest growth has usually

mussels depends on site-specific environmental been recorded in larvae fed a mixture of nakedfactors, such as storms, salinity, temperature, flagellates (Bayne 1976b), but little informationand type of predators (Seed 1976). Thompson exists on the natural food of larval blue(1984b) reported that in a Newfoundland mussel mussels. Obviously adequate food of a suitablepopulation, mortality was highest during the size is essential for the survival andfirst 2 years after recruitment. Annual development of larval blue mussels, which havemortality rate was low (5%-16%) at such sharply limited nutrient reserves. Indeed,intermediate ages but increased to 91% in blue Sastry (1979) postulated that bivalves may timemussels over 9 years old. their reproductive cycle to ensure synchrony

between larval development and a suitableECOLOGY supply of food. However, larval mussels can

withstand starvation for periods of as long asFeeding and Nutrition 10 days (at 16 °C) without adverse side effects

on later development (Bayne 1965).The blue mussel, both as a planktotrophic

larva and as an adult, is an active suspension In adults the gills, which consist of fourfeeder, deriving its nutrition by filtering demibranchs each comprising numerous ciliatedorganic particles from the water column, filaments, constitute the feeding organ as wellPhytoplankton cells are the dominant food as the site for gas exchange. Water enterssource for all life stages (Bayne 1983). the mantle cavity through the inhalant siphonEvidence for the role of detritus in the and is moved through the ostia (the spacesnutrition of the blue mussel is equivocal between adjacent filaments) by the action of(Williams 1981), but there is no reason to lateral cilia. The water exits from the

* 13

suprabranchial chamber via the exhalent of mussel, but is infinitely adjustable betweensiphon. The retention efficiency of the gill is zero and a size-dependent upper limit. Thehigh for particles larger than 5 pm, but actual filtration rate of a mussel at anydeclines sharply for smaller particles, such that particular time is the result of a complexparticles smaller than 2 pm are retained with balance between endogenous factors (e.g.,lovA efficiencv (Mohlenberg and Riisgard 1978). energy demands and degree of acclimation to

environmental variables) and exogenous factors.Food particles travel in the oral food The only exogenous factor discussed here is

groo, es to the two pairs of labial palps, which the influence of particle concentration; otherare ridged sorting organs. The palps of key environmental determinants of filtrationbi\alve molluscs not only serve to control the activity (e.g., temperature, salinity, oxygentotal ,,mount of food ingested but also its tension) are discussed later.organic composition (Newell and Jordan 1983),so that the ration ingested by the blue mussel The blue mussel is capable of adjustingis enriched in organic particles, compared to its filtration rate to maintain a complexthe particle composition in the water (Kiorboe balance between the amount of materialet al. 1980). The material rejected by the filtered, the amount rejected as pseudofeces,palps, together with some large particles and the amount ingested (for a detailed reviewrejected directly by the gills, form aggregates see Bayne and Newell 1983; Bayne et al. 1987).loosely bound in mucus. These pseudofeces are The animal is not stimulated to feed atexpelled through the inhalant siphon but are extremely low particle concentrations (ca. <1close enough to the exhalent siphon to be mg" 1-1) but filtration increases rapidly withentrained in the current and carried away increasing particle concentration. The(Foster-Smith 1975). filtration rate reaches a plateau at particle

concentrations of 1-5 mg 1-1 and declines toIngested particles enter the stomach, zero only at particle concentrations over ca.

where they are subject to a combination of 200 mg -1-1 (Widdows et al. 1979a). Evenenzymatic and mechanical attack from the though the mussel is capable of filtering largecontinuously revolving crystalline style. amounts of material from suspension, theParticles are also sorted in the stomach, with amount ingested is finite and depends on gutsome particles being channeled by ciliary size (which is a function of body size) and gutcurrents into the digestive diverticula and residence time. Increasing proportions of theothers, of possibly lower nutritional value and filtered material are rejected as pseudofeces atin excess of the capacity of the digestive concentrations above 5 mg -I-1; the ingestiondiverticula to process, constitute the intestinal rate is highest at concentrations between 5feces which are removed by ciliary tracts from and 10 mg • 1-1 at which point all furtherthe stomach into the mid-gut. Particles material filtered is rejected as pseudofeces.directed into the ducts of the digestive The large amounts of material ingested arediverticula are taken into digestive cells by first sorted on the palps, ensuring that even inendocytosis and are subject to intracellular environments with a low ratio of organic fooddigestion for periods of many hours (for to inorganic particles, the animals ingestsreview see Bayne et al. 1976a). Assimilated predominately organic particles (Kiorboe et al.material diffuses into the blood system and the 1980). Thus, the maintenance of a highundigested fragments (glandular feces) are filtration rate, followed by efficient particleejected into the duct and thence into the sorting, is not a wasteful strategy because thestomach and mid-gut. At this point, intestinal energetic costs of filtration are relativelyand glandular feces are joined into a single small, whereas those of digesting the food aremucus-coated fecal ribbon that passes through high (Bayne and Newell 1983). Mussels canthe anus and is carried away in the exhalent compensate for dietary changes by increasingwater current, their ingestion rate, absorption efficiency, and

the efficiency of the digestive process to helpThe volume of water swept completely offset decreases in the organic content of the

clear of particles per unit time is termed the food (Bayne et al. 1987). However, as withfiltration or clearance rate. The filtration physiological adaptations to otherrate is not constant for any particular weight environmental perturbations (e.g., temperature)

14

an a.'I matIon period of about 2 we eeks is mortalities been ascribed to infestation by aneeii 5 1or the cmipensation mechanisms to parasite. flowever, off Prince Ed k*ard Island,be t'lI ) it'soked. Ilh-. such mechanisms are Canada, a haplosporidian tentatively identifiedhike!, t,) t'e more important in mediating the as Labvrinthomvxa sp. (Li and ('l'burne 1979)

, ponse to seasonal changes in food did cause extremely high mortaities.qlo 1iii. i tther than short-term \ariations Generally the host-parasite relation has

ii I ith diurnal fluctuations in evolved to avoid host mortality ([.aucknerphtpiLnkt, p ,puhlolioow, or resuspension of 1983), although sublethal effects often occur.etnimcrit '\ ,:ha nc in tidal current 'elocit.,. For example, the trematode Bucephalus sp..

which lises in the gonad of the blue mussel,I r .! can castrate both sexes. Although castration

does not affect the host's surs ival, iti, pi ,,urc on the blue mussel is ultimately can compromise the sursisal of the

hikh.5 l ILIIilIg the 3 skeeks when it is a population by reducing fecundity.p IIn,:I" aT'la. f)r it is then subject togr ,ziino. t rm a ,ide \ ariet, of species, ranging The blue mussel is host to a pea crabrm 1l Ist to larsal and adult fishes. After macroparasite (Pinnotheres maculatus being

metam,,rphos ipredation can limit the distance more commonly found than P. ostreuni [Schmittthe HLue nu,sel penetrates into the sub- et al. 1973]) which lives firmly attached b\ itslittoral zone Paine 1971. 197 4). Generalls rear legs to the gill of the bivalve. In thispredation i, highest on the smallest individuals position, the crab feeds on food particlesthat has e the "eakest shells. Once a mussel traseling in the food grooves and can causeha i attained a relatisel, large and thick shell se\ ere gill damage, resulting in both a(4-5 cm) it is 5,ulnerable to attack by onl, the reduction in filtration (Pregenzer 1979) ands;tronget predators (e.g.. large starfish, large metabolic rate (Bierbaum and Shumway 1988).crutaceans, and some birds). Pea crabs are generally confined to sublittoral

blue mussel populations south of Cape CoMIn some localities, birds are the most w&here, in some populationc, ii, iestation rates

I.oracious predators of the blue mussel: up to may be as higi as 70% (Schmitt et al. 1973,70' of the net annual production of some bierbaum and Shum.ay 1988). The spionidmussel populations in Scotland is eaten by polychaete Polydora sp. bores its way into thebirds 1\1i;Inc anci Dunnet 1972). On the east shell of blue mussel and other molluscs as acoast of the United States, common avian refuge. If the polychaete's tube penetratespredators include some species of diving duck the inner surface of the shell, the bialseleg., the common eider Somateria mollissima), seals the perforation with a new layer ofvarious ,pecies of gulls, and the American conchyolin and nacre shell, thus forming ao.stercatcher Ilaeniatopus palliatus. The distinct blister (Kent 1979). Blue mussels withaquatic predators are decapod crustaceans, heavy infestations of Polydora sp. may haveincluding the American lobster (Homarus significantly lower tissue weights than thoseamericanus), crabs (e.g., Cancer irroratus, with lighter infestations (Kent 1979).Cancer borealis, and Carcinus maenasl, starfish(\sterias sp.). whelks (e.g., Thais lapillus andBuccinum undatum , and \arious fish species Competitors(e.g.. l Ii tog)a oniti s and -autogolabrusadspersu [Olla et al. 1975]). Because most The adult blue mussel on the east coastaquatic predators of the mussel are marine, of the United States is a "competitivelow salinity estuarine environments provide a dominant," although the juveniles can be inrefuge front predation for adult blue mussels, competition for settlement space with barnacles

(Seed 1976). Generally, space occupied by blueParasites and Diseales mussels becomes available for other species

only as a result of the removal of entirethe blue mussel, in common with other sections of mussel beds by storms or the

bivalse species, is host to numerous parasites elimination of large numbers of animals byof man. species (lauckner 1983). In only predators (Seed 1976). Intraspecific comp-isolated instances hae extensive blue mussel etition is high for the blue mussel due to its

gregarious settling behaxior which leads to lethal temperature response of the blue musselsextremely high population densities (Thorson depends on the animal's previous thermall'5) \nimals within these dense clumps history. In mussels acclimated to anconsequently must filter water in which food intermediate temperature (20 °C) andconcentration has been reduced by the feeding transferred to water at 27.5 °C, the "time toacti'it of neighboring mussels (Wildish and 50% mortality" was 350 h, which was about 8Kristmanson 1984: Frechette and Bourget 1985). times as long as that of mussels acclimated toSuch animals generally do not die, but their 10 °C. Tolerance of elevated temperature wasgrowth rate is reduced until they either also affected by reproductive condition; it wasmigrate to the outer edge of the clump lower in ripe than reproductively quiescent(Harger )968) or the surrounding mussels are blue mussels. Bayne et al. (1977) also reportedremoved by other factors (e.g., wave action or that a temperature of 30 °C was tolerated bypredators), small mussels (1-2 cm) twice as long as larger

ones (>5 cm).

ENVIRONNIENTAL REQUIREMENTS Blue mussels tolerate low temperaturesfor extended periods, even to the extent of

The blue mussel typically inhabits littoral being frozen in ice for up to 8 months eachto shallow sublittoral areas in oceanic and year in Labrador (Seed 1976). Williams (1970)polyhaline to mesohaline estuarine environ- demonstrated that the animal could not recoverments. Littoral estuarine environments are the if its tissue temperature dropped below -10 tomost variable of all marine systems in such -15 °C. At lower temperatures more than 65%environmental factors as temperature, salinity, of the body water freezes, causing irreversibleduration of exposure to air, and concentration tissue damage. The northward sublittoralot suspended particles (Newell 1979). The blue distributional limit of the species is notmussel has thus evolved a suite of determined by its tolerance of low temperaturesophisticated behavioral, physiological, and because sea water never gets colder than aboutbiochemical adaptations that enable it to -1.5 °C. Instead, it becomes limited by thesurvive in such a rigorous environment. These requirement for water temperatures aboveadaptations make it impossible to define for approximately 5 °C that last long enough tothe blue mussel a narrow range of allow somatic and germinal growth to occur.environmental criteria that uniquely describe This fact emphasizes the necessity forits habitat. Moreover, the blue mussel is understanding how a species responds tosubjected to simultaneous fluctuations in a typical daily and seasonal temperaturevariety of environmental factors, and its fluctuations within its habitat, in addition toresponse is to the total resulting stimulus, understanding its tolerance of environmentalrather than to single environmental variables, extremes in temperature.An example of the consequences of suchsynergistic interactions is that individuals may Blue mussels are ectothermic organisms, inbe able to survive either elevated temperatures which tissue temperatures are determined byor lowered salinities, but cannot survive both ambient water or air temperatures. Metabolicperturbations concurrently. processes of the blue mussel are not passively

regulated by environmental temperatureTemperature however, as some rate functions can be

adjusted to render them relatively independentThe blue mussel along the east coast of of variations in environmental temperature (see

the United States cannot establish permanent review by Bayne et al. 1976a; Newell 1979).inshore populations farther south than CapeHatteras because the adults are incapable of The metabolic responses of the bluesurviving in these waters, where summer water mussel to a non-lethal change in temperaturetemperatures exceed 27 °C (Wells and Gra, have been separated on the basis of the time1960). This temperature closely corresponds course of the response (Bayne et al. 1976a).with a laboratory estimate of an upper lethal An acute response occurs within the first fewtemperature of 27-29 °C made by Bayne at al. hours after an abrupt change in temperature.(1977), who also demonstrated that the upper The response is characterized by an alteration

16

in rates of oxygen consumption, filtration. etc., temperatures, which ranged up to 26 'C in thewhich are totally dependent on the magnitude south but only from 14 to 17 °C in the north.and direction of the temperature fluctuation.If the change in temperature is maintained the Thompson and Newell (1985) suggestedacute response is superseded, over an that "it is unsatisfactory to define rigidly aapproximately 14-day acclimation period, by a particular suite of physiological responses tosuite of physiological and biochemical temperature as characteristic" of a species asadaptations that enable the metabolism to widely distributed as the blue mussel. Instead,return to near the level prevailing before the the response of different populations of thetemperature changed (reviewed by Bayne et al. blue mussel to a change in temperature must1976a). If the temperature change represents be viewed as a complex balance between eacha permanent shift in the environment (e.g., the population's thermal history, food availability,thermal effluent plume from a power station), reproductive condition (Widdows 1978), andthe blue mussel population may have to evolve genetic composition.genetically. Such genetic adaptations governthe upper and lower temperature limits. Salinity

The blue mussel is a euryhaline speciesWiddows (1976) showed that the blue that occurs in environments ranging from full

mussel adjusted its filtration rate completely, oceanic salinities (34 ppt) to mesohaline (5-18and metabolic rate partly, to a sinusoidal ppt) estuarine conditions (Bayne et al. 1976a).temperature cycle that varied between II and As discussed in the life history section, the19 °C everv 24 h. The time course of range of salinities that allows normal larvaladaptation was about 14 days, which was development may be more restricted than thesimilar to the time required for blue mussels range tolerated by adults. Blue mussels areto adjust to constant changes in temperature. osmoconforming, i.e., the osmotic pressure ofThe final level to which the metabolic rate the intracellular fluids is kept isosmotic withand filtration were adjusted was similar to the medium by the adjustment of thethese levels in animals acclimated to a concentration of free amino acids (Bayne et al.constant 15 °C, and intermediate between the 1976b).levels recorded for the animals maintained at aconstant I I °C or 19 °C. Many estuarine habitats are characterized

by fluctuations in salinity associated with theThompson and Newell (1985) demonstrated normal ebb of low salinity waters from the

a difference in resporse to temperature estuary and the flood of higher salinity watersbetween latitudinally separated blue mussel back into the estuary. If the tidal variationpopulations. Animals from Long Island Sound, in salinity is small (< 10 ppt), the blue musselNY, acclimated their feeding rate to remains active throughout the salinitytemperatures within the range of 5-25 °C, fluctuation (Widdows 1985). In response to athough their metabolic rate did not acclimate rapid drop in ambient salinity, such as mayto temperatures above 20 °C. These southern occur with the ebb tide in estuaries with amussels sustained a positive energy balance, large input of fresh water, the blue musseland only 10% died after 26 days, even at the first closes its exhalent siphon to stop thenear-lethal temperature of 25 °C. Mussels ventilation of the mantle cavity, and thenfrom near the northern limits of distribution in closes its shell if the salinity change is largeNewfoundland acclimated neither their feeding enough (reviewed by Davenport 1982). It canrate nor their metabolic rate to temperatures thus effectively isolate its tissue from up tooutside the experimental range of 5-20 °C. half the change in ambient osmoticThey were so severely stressed at 25 °C that concentration (Shumway 1977). Shell closurethey did not sustain a positive energy balance cannot be maintained longer than about 96 hand consequently catabolized nutrient reserves; (Gilles 1972) because the animal must rely onas a consequence, nearly 50% died within 26 stored nutrient reserves and anaerobicdays. Thompson and Newell (1985) explained metabolism to sustain energy demands. If thethese differences as being due to the change in ambient salinity is not a transientdifferences in exposure to summer water event, but represents a longer term change in

*L 17

en) ironmental conditions, the animal opens its habitats and the stunting effect of theshell and adjusts osmotically to the ambient extensive disturbance of feeding and exposureconditions (Bayne et al. 1976b; Widdows 1985) to air in open coastal populations (Seed 1976).

In addition, predation may be so severe in theThe genetic basis of some aspects of the exposed sea coast populations that few mussels

response to salinity change of the blue mussel survive into their third year (Seed 1969).from populations in the North and Mid-Atlantic Regions have been elucidated Oxygen(reviewed by Koehn 1983, Koehn and Hilbish1987). The enzyme aminopeptidase- I is Oxygen diffuses into the blue musselinvolked in producing some of the free amino across the gill, where there is close contactacids that the blue mussel uses to regulate its between the water and the hemolvmph pumpedintracellular osmotic pressure. There are six through the gill filaments by the heart. Therecommon allozynes of aminopeptidase-I, all of are no oxygen-carrving pigments in the bloodwhich hase different specific activities. In (Newell 1979). During exposure to air theoceanic blue mussel populations a blue mussel has only a limited capacity topreponderance of indi, iduals produce the utilize atmospheric oxygen because the valvesalloz.me with the highest specific activity; in must be tightly closed to avoid desiccationlow salinity populations most individuals (Widdows et al. 1979b). During periods ofproduce the alloz.me with the lowest specific shell closure the oxygen in the water retainedactivity. Thus, oceanic mussels can more in the mantle cavity is used first; thereafterrapidly produce greater quantities of some of the animal's tissues are subject to hypoxicthe amino acids used in mediating their conditions, and energ, requirements areresponse to a salinity change. Although larvae supplied by anaerobic metabolic pathwaysfrom the high salinity populations can settle in (Gabbott 1976).estuaries, the) die within a few months aftersettlement (Koehn et al. 1980). Under certain environmental conditions

dissolved oxygen concentrations are reduced inSubstrate and Current estuarine and coastal waters with restricted

circulation, due to the high biological oxygenThe mussel is an epibenthic species that demand of decomposing organic matter. If the

as an adult lives in areas with substrates waters become anoxic, the concentration ofranging from rock to coarse gravel; even areas hydrogen sulfide produced is toxic to manywith mud and sand substrates can be colonized animal species, including the blue mussel.provided that there is a firm surface, such as Theede et al. (1969) reported that undera stone or another mussel shell, to which the laboratory conditions the blue mussel survivedb\ssus threads can be attached. In areas 35 days in water at 10 °C containing only 0.15sheltered from fast currents and high energy ml O 2 • 1

- 1, but survival was reduced to 25,waes, mussels can build dense beds as a days when hydrogen sulfide was present.result of their gregarious settlement behavior.Such beds can become unstable as the In response to a gradual decline inattachment of the lower mussels to firm oxygen content, the blue mussel can increasesurfaces is strained by a large mas5 of mussels its extraction efficiency for oxygen. Oxygenabove them. Eentually such dense beds are consumption is thus regulated to bedislodged by wave action during storms and independent of the availabilit. ofan, mussels that survive have to reattach to environmental oxygen (Bayne et al. 1976b).a~ailable substrate (Seed 1976). When oxygen availability declines below 60% of

saturation, the mussel is unable to compensateThe blue mussel requires sufficient water by further increases in extraction efficiency.

flow to ensure larval dispersal and carry As a consequence, the mussel's oxygen uptakesuspended food particles. It tends to attain a declines rapidly, in direct proportion to thelarger size in sheltered environments than in decline in environmental oxygen concentrationmore exposed open coast conditions (Seed (Bayne et al. 1976b). Such a decrease in1976). This differential size is probably due to oxygen consumption does not necessitate adifferences in food availability between reduction in energy production, since anaerobic

18 O

pathwAa,,s are proportionally induced as mental Protection Agency. An excellenten% ironmental oxygen levels drop below 90% of review of the extensive literature on, andsaturation (Famme et al. 1981). This use of methods for assessing, the effects of stressanaerobic pathways enables the metabolic rate, and pollution on marine invertebrates wasas measured by heat output, to be sustained compiled by Bayne et al. (1985).near the aerobic rate during brief periods ofshell closure or hypoxia. One general conclusion from these studies

must be emphasized. Much of the original-Xnthropogenic Contaminants pollution research was designed to determine

the time or concentration of contaminantsFhe blue mussel has been the subject of required to cause a 50% mortality in a test

innumerable studies of its response to population. Such studies generally involvedanthropogenic pollutants. Its widespread use concentrations that greatly exceeded thosefor such studies reflects the broad commonly found in the environment. Recentgeographical distribution of the species and the studies, pioneered with the blue mussel as afact that it is sessile and intimately exposed test species, have emphasized the sublethalto large %olumes of water as a result of its effects of pollutants. That is, adults mightsuspension feeding activities. The animal is not die, or even be obviously affected, as aalso relati',el', easy to collect and maintain in result of exposure to a contaminant, butthe laboratory. The monitoring of certain aspects of their physiology might beph~siological and biochemical changes in blue disrupted. If this disruption is prolonged, itmussels subject to pollution, or the monitoring can (for example) reduce the energy thatof chemicals in the tissue, provides a individuals have available to partition intobihologicall, rele.ant method for quantifying somatic and germinal growth. As reviewed inthe bioa, ailabilit, of contaminants in the the reproductive strategy section above, anyen% ir,,nment. The use of the blue mussel for reduction in the nutrient reserves of the eggthis purpose was the objective of the can reduce larval viability. Thus the stress onInternationail \iisel Watch Program and the adult is likely to ultimately affect theWkorkshop (National Academy of Sciences 1980) viability of the population by reducingv, hich is being continued by the U.S. Environ- recruitment.

*I 19

LITERATURE CITED

Abbott, R.T. 1975. American Seashells, 2nd ed. Bayne, B.L., J. Widdows, and R.J. Thompson.Van Nostrand Reinhold, New York. 568 pp. 1976b. Physiological integrations, Pages 261-

291 in B.L. Bayne, ed. Marine mussels: theirBayne, B.L. 1963. Responses of Mytilus dulis ecology and physiology. Cambridge University

larvae to increases in hydrostatic pressure. Press, New York.Nature (Lond.) 198:406-407.

Bayne, B.L., J. Widdows, and C. Worrall. 1977.Ba.ne, B.L. 1964. The responses of the larvae Some temperature relationships in the

of Mytilus edulis L. to light and gravity, physiology of two ecologicall, distinctOikos 15:162-174. bivalve populations. Pages 379-400 in F.J.

Vernberg, A. Calabrese, F. Thurnberg and W.Bayne, B.L. 1965. Growth and the delay of Vernberg, eds. Physiological responses of

metamorphosis of the larvae of Mytilus marine biota to pollutants. Academic Press,edulis L. Ophelia 2:1-47. New York,

Bayne, B.L. ed., 1976a. Marine mussels: their Bayne, B.L., D.L. Holland, M.N. Moore, D.M.ecology and physiology. Cambridge University Lowe, and J. Widdows. 1978. Further studiesPress, New York. 506 pp. on the effects of stress in the adult on the

eggs of Mytil edulis. J. Mar. Biol. Assoc.Bayne, B.L. 1976b. The biology of mussel U.K. 58:825-841.

larvae. Pages 81-120 in B.L. Bayne, ed.Marine mussels: their ecology and physiology. Bayne, B.L., A. Bubel, P.A. Gabbott, D.R.Cambridge University Press, New York. Livingstone, D.M. Lowe, and M.N. Moore.

1982. Glycogen utilisation and gametogenesisBayne, B.L. 1983. Physiological ecology of in Mytilus edulIs L. Mar. Biol. Lett. 3:89-105.

marine molluscan larvae. Pages 299-342 inN.i. Verdonk, J.A.M. van den Biggelar, and Bayne, B.L., D.A. Brown, K. Burns, D.R. Dixon,A.S. Tompa, eds. The Mollusca. Volume 3. A. Ivanovici, D.R. Livingstone, D.M. Lowe,Development. Academic Press, New York. M.N. Moore, A.R.D. Stebbing, and 3.

Widdows. 1985. The effects of stress andBayne, B.L., and R.C. Newell. 1983. pollution on marine animals. Praeger Press,

Physiological energetics of marine molluscs. New York. 384 pp.Pages 407-515 in A.S.M. Saleuddin and K.M.Wilbur, eds. The Mollusca. Vol. 4. Physiology, Bayne, B.L., A.J.S. Hawkins, and E. Navarro.Part 1. Academic Press, New York. 1987. Feeding and digestion by the mussel

Mytilus edulis L. (Bivalvia: Mollusca) inBayne. B.L., P.A. Gabbott, and J. Widdows. mixtures of silt and algal cells at low

1975. Some effects of stress in the adult on concentrations. J. Exp. Mar. Biol. Ecol.the eggs and larvae of Mytilus edulis L. J. 111:1-22.Mar. Biol. Assoc. U.K. 55:675-689.

Bayne, B.L., R.J. Thompson, and J. Widdows. Bierbaum, R., and S.E. Shumway. 1988.1976a. Physiology I. Pages 121-206 in B.L. Feeding and oxygen consumption in mussels,Bayne, ed. Marine mussels: their ecology and Mvytilus edulis, with and without pea crabs,physiology. Cambridge University Press, NY. Pinnotheres maculatus. Estuaries. 11:264-271.

021

3irbeck, I It., and J.(;. Mclenery. 1982. avqilable to an intertidal mussel bed. Can. J.Degradation of ba:teria b' \Nhtilus edulis. Fish. Aquat. Sci. 42:1158 -1165.Mfar 13iol. 7-': 1 5.

Gabbott, P.A. 1976. Energy metabolism. Pages(arter, G-\. 1980. Selected mineralogical data 293-355 in B.L. Bayne, ed. Marine mussels:

for the t1ial\ ia. Pages 627-643 in D.A. their ecology and physiology. CambridgeRhoads and R.A. lutz, eds. Skeletal growth University Press, New York.of aquati, organisms. Plenum Press, New

o , rk. Gabbott, P.A. 1983. Developmental andseasonal metabolic activities in marine

Chalfant, I.S., T. Archambault, and A.E. West. molluscs. Pages 165-217 in P.W. Hochachka,1980. Natural stocks of mussels: growth, ed. The Mollusca. Volume 2. Environmentalrecruitment and harvest potential. Pages 38- biochemistry and physiology. Academic Press,68 Ln R.-\. Lutz. ed. Mussel culture and New York.har\,est: a North American perspective.Llse\ier Scientific Publishing, Amsterdam, Gilles, R. 1972. Osmoregulation in threeI toIl and. molluscs: Acanthochitona discrepans (Brown).

Glycymeris glycvmeris (L.) and Mytilus edulisClifton, J.A. 1980. Some economics of mussel L. Biol. Bull. (Woods Hole) 142:25-35.

culture and harvest. Pages 312-338 in R.A.lutz, ed. Mussel culture and harvest: a lalstead, B.W. 1965. Poisonous and venomousNorth American perspective. Elsevier animals of the world, Volume I.Scientific Pubishing, Amsterdam, Holland. Invertebrates. U.S. Government Printing

Office, Washington, DC 994 pp.Crosb.' NI P. 1987. Utilization of detrital

complexes by the oyster Crassostrea virginica [larger, J.R.E. 1968. The role of behavioral(Grueling. Ph.D. Thesis. University of traits in influencing the distribution of twoMars.land, College Park. 175 pp. species of sea mussel, Mytilus edulis and M.

californianus. Veliger 11:45-49.Davcnport, J. 1982. Environmental simulation

experiments upon marine and estuarine Hilbish, T.J. 1986. Growth trajectories of shellanimals. A.dv. Mar. Biol. 19:133-256. and soft tissue in bivalves: seasonal variation

in Mytilus edulis L. J. Exp. Mar. Biol. Ecol.Famine. P., J. Knudsen, and E.S. Hansen. 1981. 96:103-113.

The effect of oxygen on the aerobic-anaerobic metabolism of the marine bivalve, Hrs-Brenko, M., and A. Calabrese. 1969. TheM',tilus edulis. Mar. Biol. Lett. 2:345-351. combined effects of salinity and temperature

on larvae of the mussel Mytilus edulis. Mar.Biol. (Berl.). 4:224-226.

Fish, C'.J., and M.W. Johnson. 1937. Thebiology of the zooplankton in the Bay of Incze, L.S., and R.A. Lutz. 1980. MusselFundv and Gulf of Maine with special culture: an East Coast perspective. Pages 99-reference to production and distribution. 1. 140 in R.A. Lutz, ed. Mussel culture andBiol. Board Can. 3:189-322. harvest: a North American perspective.

Elsevier Scientific Publishing, Amsterdam,Foster-Smith, R.L. 1975. The effect of Holland.

concentration of suspension on the filtrationrates and pseudofaecal production forMytilu5 edulis L., Cerastoderma edule(L.) and Innes, D.J., and L.E. Haley. 1977. GeneticVenerupis Dullastra (Montagu). J. Exp. Mar. aspects of larval growth under reducedBiol. Ecol. 17:1-22. salinity in Mytilus edulis. Biol. Bull. (Woods

Hole). 153:312-321.Frechette, M., and E. Bourget. 1985. Energy

flow between the pelagic and benthic zones: Jorgensen, C.B. 1981. A hydromechanicalfactors controlling particulate organic matter principle for particle retention in Mytilus

22

eduls and other ciliary feeders. Mar. Biol. mussel Mytilus edulis L. J. Mar. Biol. Assoc.61:277-282. U.K. 62:133-145.

Jorgensen, C.B., T. Kiorboe, F. Mohlenberg, Lutz, R.A. 1976. Annual growth patterns inand H.U. Riisgard. 1984. Ciliary and mucus- the inner shell layer of Mytilus edulis L. 1.net filter feeding, with special reference to Mar. Biol. Assoc. U.K. 56:723-731.fluid mechanical characteristics. Mar. Ecol.Prog. Ser. 15:283-292. Lutz, R.A., ed. 1980. Mussel culture and

harvest: a North American perspective.Kent, R.M.L. 1979. The influence of heavy Elsevier Scientific Publishing, Amsterdam,

infestations of Polydora ciliata on the flesh Holland. 350 pp.content of Mytilus edus. J. Mar. Biol.Assoc. U.K. 59:289-297. Lutz, R.A., and H. Hidu. 1979. Hinge

morphogenesis in the shells of larval andKiorboe, T., F. Mohlenberg, and 0. Nohr. 1980. early post-larval mussels (Mytilus edulis L.

Feeding, particle selection and carbon and Modiolus modiolus (L.)). J. Mar. Biol.absorption in Mytilus edulis in different Assoc. U.K. 59:111-121.mixtures of algae and resuspended bottommaterial. Ophelia 19:193-205. Mason, J. 1976. Cultivation. Pages 385-410 in

B.L. Bayne, ed. Marine mussels: their ecologyKoehn, R.K. 1983. Biochemical genetics and and physiology. Cambridge University Press,

adaptation in molluscs. Pages 305-330 in P.W. New York.Hochachka, ed. The Mollusca. Volume 2.Environmental biochemistry and physiology. Mileikovsky, S.A. 1973. Speed of activeAcademic Press, New York. movement of pelagic larvae of marine bottom

invertebrates and their ability to regulateKoehn, R.K., and T.J. Hilbish. 1987. The their vertical position. Mar. Biol. 23:11-17.

biochemical genetics and physiologicaladaptations of an enzyme polymorphism. Am. Miller, B.A. 1980. Historical review of U.S.Sci. 75:134-141. mussel culture and harvest. Pages 18-37 in

R.A. Lutz, ed. Mussel culture and harvest: aKoehn, R.K., R.I.E. Newell, and F.W. North American perspective. Elsevier

Jmmermann. 1980. Maintenance of an Scientific Publishing, Amsterdam, Holland.aminopeptidase allele frequency cline byPatural selection. Proc. NatI. Acad. Sci. Milne, H.A., and G.M. Dunnet. 1972. StandingU.S.A. 77:5385-5389. crop, productivity and trophic relations of

the fauna of the Yth~n estuary. Pages 86-Kreeger, D., C.J. Langdon, and R.I.E. Newell. 106 in R.S.K. Barnes ad J. Green, eds. The

1988. Utilization of refractory cellulosic estuarine environment. Associated Scientificcarbon derived from Soartina alterniflora by Publishers, Amsterdam.the ribbed mussel, Geukensia demissa. Mar.Ecol. Prog. Ser. 42:171-179. Mohlenberg, F. and H.U. Riisgard. 1978.

Efficiency of particle rtention in 13 speciesLauckner, G. 1983. Diseases of Mollusca: of suspension feeding bivalves. Ophelia

Bivalvia. Pages 477-961 in 0. Kinne, ed. 17:239-246.Diseases of marine animals. Volume II.Biologische Anstalt Helgoland, Hamburg, WestGermany. National Academy of Sciences. 1980. The

International Mussel Watch. NationalLi, M.F., and S. Clyburne. 1979. Mortalities of Academy of Sciences, Washington, D.C. 248

blue mussels (Mytilus edulis) in Prince pp.Edward Island. J. Invert. Pathol. 33:108-110.

National Marine Fisheries Service, Office ofLowe, D.M., M.N. Moore, and B.L. Bayne. 1982. Data and information Management,

Aspects of gametogenesis in the marine Washington, D.C.

*23

Newell, R.C. 1979. Biology of intertidal animals. Rodhouse, P.G., C.M. Roden, M.P. Hensey, T.Marine Ecological Surveys Ltd., Faversham, McMahon, B. Ottway, and T.H. Ryan. 1984.U.K. 781 pp. Food resource, gametogenesis and growth of

Mytilus edulis on the shore and in suspendedNewell, R.I.E., and S.J. Jordan. 1983. culture: Killary Harbour, Ireland. J. Mar.

Preferential ingestion of organic material by Biol. Assoc. U.K. 64:513-529.the American oyster, Crassostrea virpinica.Mar. Ecol. Prog. Ser. 13:47-53. Rodhouse, P.G., J.H. McDonald, R.I.E. Newell,

and R.K. Koehn. 1986. Gamete production,Newell, R.I.E., and C.J. Langdon. 1986. somatic growth and multiple-locus enzyme

Digestion and absorption of refractory heterozygosity in Mytilus edulis. Mar. Biol.carbon from the plant Snartina alterniflora (Berl.) 90:209-214.by the oyster Crassostrea virginica. Mar.Ecol. Prog. Ser. 34:105-115. Sastry, A.N. 1979. Pelecypoda (excluding

Ostreidae). Pages 113-292 in A.C. Giese andNewell, R.I.E. and R.J. Thompson. 1984. J.S. Pearse, eds. Reproduction of marine

Reduced clearance rates associated with invertebrates. Volume V. Academic Press,spawning in the mussel, Mytilus edulis (L.) New York.(Bivalvia, Mytilidae). Mar. Biol. Lett. 5:21-33.

Schmitt, W.L., J.C. McCain and E.S. Davidson.Newell, R.I.E., T.J. Hilbish, R.K. Koehn, and 1973. Decapoda I., Brachura I, Family

C.J. Newell. 1982. Temporal variation in the Pinnotheridae. in H.-E.Gruner and L.B.reproductive cycle of Mytilus edulis Holthuis, eds. Crustaceorum Catalogus. Part(Bivalvia, Mytilidae) from localities on the 3. Dr. W. Junk bv Publishers, the Hague.east coast of the United States. Biol. Bull. 160 pp.(Woods Hole) 162:299-310.

Seed, R. 1969. The ecology of Mytil edulisNixon, S.W., C.A. Oviatt, C. Rogers, and K. L. (Lamellibranchiata) on exposed rocky

Taylor. 1971. Mass and metabolism of a shores. 2. Growth and Mortality. Oecologiamussel bed, Oecologia (Berl.) 8:21-30. (Berl.) 3:317-350.

Olla, B.L., A.J. Bejda, and A.D. Martin. 1975. Seed, R. 1976. Ecology. Pages 13-65 in B.L.Activity, movements, and feeding behavior of Bayne, ed. Marine mussels: their ecology andthe Cunner, Tautogolabrus adspersus, and physiology. Cambridge University Press, Newcomparison with young Tautog, Tautoga York.onitis, off Long Island, New York. Fish.Bull., U.S. 73:895-900. Shumway, S.E. 1977. Effect of salinity

fluctuation on the osmotic pressure and Na+,Paine, R.T. 1971. A short term experimental Ca 2 + and Mg 2 + ion concentrations in the

investigation of resource partitioning in a haemolymph of bivalve molluscs. Mar. Biol.New Zealand rocky intertidal habitat. (Ber!.) 41:153-177.Ecology 52:1096-1106.

Sprung, M. 1984. Physiological energetics ofmussel larvae (Mvtilus 1dulis). 1. Shell

Paine, R.T. 1974. Intertidal community growth and biomass. Mar. Ecol. Prog Ser.structure. Experimental studies on the 17:283-293.relationship between a dominant competitorand its principal predator. Oecologia (Berl.) Theede, H., A. Ponat, K. Hiroki, and C.15:93-120. Schlieper. 1969. Studies on the resistance of

marine bottom invertebrates to oxygen-deficiency and hydrogen sulphide. Mar. Biol.

Pregenzer, C. 1979. Effect of Pinnotheres (Berl.) 2:325-337.hickmani on neutral red clearance by Mvtilustduis&. Aust. J. Mar. Freshwater Res. 30:547- Theroux, R.B., and R.L. Wigley. 1983.550. Distribution and abundance of east coast

24

bivalve molluscs based on specimens in the performance of Mytilus edulis L. Pages 555-National Marine Fisheries Service Woods 566 in J.S. Gray and M.E. Christiansen, eds.Hole collection. NOAA technical report Marine biology of polar regions and effectsNMFS SSRF-768. US Government Printing of stress on marine organisms. John Wiley,Office, Washington, D.C. London.

Thompson, R.J. 1979. Fecundity and Widdows, J., P. Fieth, and C.M. Worrall. 1979a.reproductive effort in the blue mussel Relationship between seston, available food(Mytilus edulis), the sea urchin and feeding activity in the common mussel(Strongylocentrotus droebachiensis), and the Mytilus edulis. Mar. Biol. (Berl.) 50:195-207.snow crab (Chionoecetes 2poilio frompopulations in Nova Scotia and Widdows, J., B.L. Bayne, D.R. Livingstone,Newfoundland. J. Fish. Res. Board Canada. R.I.E. Newell, and P. Donkin. 1979b.36:955-964. Physiological and bio,'hemical responses of

bivalve molluscs io exposure to air. Comp.Thompson, R.J. 1984a. The reproductive cycle Biochem. Physiol. A. 62:301-308.

and physiological ecology of the musselMytilus edulis in a subarctic, non-estuarine Wilbur, K.M., and A.S.M. Saleuddin. 1983. Shellenvironment. Mar. Biol. (Berl.) 79:277-28 . formation. Pages 235-287 in A.S.M. Saleuddin

and K.M. Wilbur, eds. The Mollusca VolumeThompson, R.J. 1984b. Production, reproductive 4. Physiology, Part i. Academic Press, New

effort, reproductive value and reproductive York, N.Y.cost in a popuiation of the blue musselMytilus duiis from a subartic environment. Wildish, D.J., and D.D. Kristmanson. 1984.Mar. Ecol. Prog. Ser. 16:249-257. Importance to mussels of the benthic

boundary layer. Can. J. Fish. Aquat. Sci.Thompson, R.J., and R.I.E. Newell. 1985. 11:1618-1625.

Physiological responses to temperature intwo latitudinally separated populations of themussel, Mytilus edulis. Pages 481-495 in P.E. Williams, P. 1981. Detritus utilization byGibbs, ed. Proceedings nineteenth European Mytilus edulis. Estuarine Coastal Shelf Sci.Marine Biology Symposium. Cambridge 12:739-746.University Press, Cambridge, U.K.

Williams, R.J. 1970. Freezing tolerance inThorson, G. 1957. Bottom communities Mytilus edulis. Comp. Biochem. Physiol.

(sublittoral or shallow shelf). Mem. Geol. 35:145-161.Soc. Am. 67:461-534.

Wells, H.W., and I.E. Gray. 1960. The seasonal Wood, L., and W.J. Hargis. 1971. Transport ofoccurrences of Mytilus edulis on the Carolina bivalve larvae in a tidal estuary. Pages 29-44coast as a result of transport around Cape in D.J. Crisp, ed. Fourth European MarineHatteras. Biol. Bull. (Woods Hol:) 119:550- Biology Symposium. Cambridge University559. Press, London.

Widdows, J. 1976. Physiological adaptations of Yentsch, C.M., and L.S. Incze. 1980.Mvtilus edulis L. to fluctuating temperatures. Accumulation of algal biotoxins in mussels.J. Comp. Physiol. 105:115-128. Pages 223-246 in R.A. Lutz, ed. Mussel

culture and harvest: a North AmericanWiddows, J. 1978. Combined effects of body perspective. Elsevier Scientific Publishing,size, food concentrations and season on the Amsterdam, Holland.physiology of Mytilus edulis. J. Mar. Biol.Assoc. U.K. 58:109-124. Yonge, C.M. 1976. The 'mussel' form and

habit. Pages 1-12 in B.L. Bayne, ed. MarineWiddows, J. 1985. The effect of fluctuating Mussels: their ecology and physiology.

and abrupt changes in salinity on the Cambridge University Press, New York.

*25

50272 -r0REPORT DOCUMENTATION 1. REPORT NO. 2. 3. Recipient's Accesson No

PAGE Biological Report 82(11.102) i4. Title and Subtitle . Reoort Date

Species Profiles: Life Histories and Environmental Requirements of June 1989Coastal Fishes and Invertebrates (Mid and North Atlantic)-blue mussel G.

7. Authow(s) S. Performng Orgenization Rapt. No.

Roger 1. E. Newell

9. Performlng Organization Name and Address 10. Proitl/Task/Work Unit No.Hori Prin* a,.,maa L,,bu,atozics

University of Maryland It. ContractlC) or Grant(G) No.

Box 775 (C)Cambridge, Maryland 21631 (G)

12. Sponsoring Organizatlon Name and Address

13. Type of Report & Period CovredU.S. Dept. of the Interior U.S. Army Corps of EngineersFish and Wildlife Service P. 0 Box 631National Wetlands Research Center Vicksburg, MS 39180 14.Washington, D.C. 20240

IS. Supplementary Notes

IS. Abstract (Limit: 200 words)

The blue mussel, Mytilus t L. is a widely distributed and locally abundant bivalve mollusc in theNorth and Mid-Atlantic Regions. It is a valuable commercial species; regional landings in 1986 wereworth nearly $4 million. It is a semi-sessile species, anchored by byssus threads to firm surfaces inlittoral and sub-littoral environments at salinities ranging from 5 to 35 ppt. It is a suspension feeder,ingesting phytoplankton and detrital particles in the size range of 3-30 rm. The geographical range ofthe species is limited by lethal water temperatures above 27"Ot in the sdoak and by temperatures too lowfor growth and reproduction in the north. Animals from the northern end of the range are stressed bytemperatures above 20 DC, whereas those near the southern distributional limit are not severely stressedby temperatures as high as 25"ffC. The blue mussel is diecious and oviparous. The planktotrophic larvaetake about 3 weeks to develop and metamorphose. The environmental tolerances of larvae are morerestricted than those of adults. The juveniles grow to approximately 1.5 mm while attached tofilamentous algae before being carried by water currents to reattach tq a firm substrate, often close toadult mussels. Larval and adult blue mussels are important prey items for many animals, including crabs,fishes, and birds.

17. Document Analysis a. Descriptors

M ussels "- . -< , ' . . . . ./

EstuariesLife cycles -

b. Identifiers/Open-Ended Terms

Blue Mussel-Mytilus edulis

c. COSATI field/Group

IS. Availability Statement It Security Class CThis Report) 21. No. of PatesUnclassified 25

Unlimited M. security Class (This peg) 2. PuceUnclassified

So ANSI-Z3.Ir MFrIO4NAL FORM 272 (4-77)(Fonnerly NTIS-35)Department of Commerce