Biological Report I82/11.84Y ~TyE.24~September 1988 DTI

Species Profiles: Life Histories and ELECTENOV 2 11988Environmental Requirements of Coastal FishesS

and Invertebrates (Pacific Southwest)

CALIFORNIA SEA MUSSEL AND BAY MUSSEL

Cn

Coastal Ecology Group*Fish and Wildlife Service Waterways Experiment Station

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

DI*titbud=w UfalriUd

Biological Report 82 11.84WO /TR/EL-82-4 $4.September 1988

Species Profiles: Life Histories and Environmental Requirementsof Coastal Fishes and Invertebrates (Pacific Southwest)

CALIFORNIA SEA MUSSEL AND BAY MUSSEL

by

William N. ShawFred Telonicher Marine Laboratory

Humboldt State UniversityTrinidad, CA 95570

Thomas J. HasslerU.S. Fish anu Wildlife Service

California Cooperative Fishery Research UnitHumboldt State University

Arcata, CA 95521and

David P. MoranU.S. Fish and Wildlife Service

National Wetlands Research Center1010 Gause BoulevardSlidell, LA 70458

Project OfficerCarroll Cordes

U.S. Fish and Wildlife ServiceNational Wetlands Research Center

1010 Gause BoulevardSlidell, 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 ServiceResearch and Development

National Wetlands Research CenterWashington, DC 20240

This series may be referenced as follows:

U.S. Fish and Wildlife Service. 1983-19 . Species profiles: life historiesand environmental requirements of coastal fishes and invertebrates. U.S. FishWildl. Serv. Biol. Rep. 82(11). U.S. Army Corps of Engineers, TR EL-82-4.

This profile may be cited as follows:

Shaw, W.N., T.J. Hassler, and D.P. Moran. 1988. Species profiles: lifehistories and environmental requirements of coastal fishes and invertebrates(Pacific Southwest)--California sea mussel and bay mussel. U.S. Fish Wildl.Serv. Biol. Rep. 82(11.84). U.S. Army Corps of Engineers, TR EL-82-4. 16 pp.

PREFACE

This species profile is one of a series on coastal aquatic organisms,principally fish, of sport, commercial, or ecological importance. The profilesare designed to provide coastal managers, engineers, and biologists with a briefcomprehensive sketch of the biological characteristics and environmentalrequirements of the species and to describe how populations of the species may beexpected to react to environmental changes caused by coastal development. Eachprofile has sections on taxonomy, life history, ecological role, environmentalrequirements, and economic importance, if applicable. A three-ring binder isused for this series so that new profiles can be added 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 ofthe 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

~iii

CONVERSION TABLE

Metric to U.S. Customary

Multiply y To Obtain

millimeters (mm) 0.03937 inchescentimeters (cm) 0.3937 inchesmeters (m) 3.281 feetmeters (m) 0.5468 fathomskilometers (km) 0.6214 statute mileskilometers (km) 0.5396 nautical miles

square meters (m2 ) 10.76 square feetsquare kilometers (km2) 0.3861 square mileshectares (ha) 2.471 acres

liters (1) 0.2642 gallonscubic meters (ml) 35.31 cubic feetcubic meters (m3) 0.0008110 acre-feet

milligrams (mg) 0.00003527 ouncesgrams (g) 0.03527 ounceskilograms (kg) 2.205 poundsmetric tons Ct) 2205.0 poundsmetric tons Ct) 1.102 short tons

kilocalories (kcal) 3.968 British thermal unitsCelsius degrees (0C) 1.8(0 C) + 32 Fahrenheit degrees

U.S. Customary to Metric

inches 25.40 millimetersinches 2.54 centimetersfeet (ft) 0.3048 metersfathoms 1.829 metersstatute miles (mi) 1.609 kilometersnautical miles (nmi) 1.852 kilometers

square feet (ft2 ) 0.0929 square meterssquare miles (mi2 ) 2.590 square kilometersacres 0.4047 hectares

gallons (gal) 3.785 literscubic feet (ft) 0.02831 cubic metersacre-feet 1233.0 cubic meters

ounces (oz) 28350.0 milligramsounces (oz) 28.35 gramspuunds (Ib) 0.4536 kilogramspounds (lb) 0.00045 metric tonsshort tons (ton) 0.9072 metric tons

British thermal units (Btu) 0.2520 kilocaloriesFahrenheil degrees (OF) 0.5556 (OF - 32 Celsius degrees

iv

CONTENTS

Page

PREFACE ................................................................ iiiCONVERSION FACTORS ..................................................... ivACKNOWLEDGMENTS ........................................................ vi

NOMENCLATURE/TAXONOMY .................................................. 1MORPHOLOGY/IDENTIFICATION AIDS ......................................... 1

California Sea Mussel ................................................ 1Bay Mussel ........................................................... 3

REASON FOR INCLUSION IN SERIES ......................................... 3LIFE HISTORY ........................................................... 3Spawning ............................................................. 3Larval Stage ......................................................... 4Postlarvae and Recruitment ........................................... 4Maturity ............................................................. 6Age and Growth ....................................................... 6

COMMERCIAL AND SPORT FISHERIES AND AQUACULTURE ......................... 7ECOLOGICAL ROLE.. ...................................................... 8

Feeding.............................................................. 8Competitors .. ........................................................ 8Predators ........................................................... 9Commensals, Parasites, and Encrusting Epifauna ....................... 10

ENVIRONMENTAL REQUIREMENTS ............................................. 10Temperature and Salinity ............................................. 10Habitat .............................................................. 11Physical Disturbance ................................................. 11Other Environmental Factors .......................................... 11

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

:~~~ ~ AAe~l FO

Accession ForNTIS GRA&I

DTIC TABUzianounoed E]

i Justification

Distr - butiou/IAvailability Codes

v Avail and/orDist Special

..... ' ', , l l I I I I

ACKNOWLEDGMENTS

We acknowledge the reviews by James Peterson, Los Angeles County NaturalHistory Museum, and Michael Martin, Califor'nia Department of Fish and Game.

vi

I.

Figure 1. Shells of the California sea mussel (A), and bay mussel (B).

CALIFORNIA SEA MUSSEL AND BAY MUSSEL

NOMENCLATURE/TAXONOMY Islands to Socorro Island, Mexico(California distribution is shown in

Scientific name ....... M__Mytilus Figure 2) and the bay mussel fromcalifornianus Conrad the Arctic Ocean to Cape San Lucas,Preferred common name . California Baja California (Fitch 1953).sea mussel (Figure 1A)Other common names . . . Rock mussel,big mussel, California mussel, sea MORPHOLOGY/IDENTIFICATION AIDSmusselScientific name . . . Mytilus edulis California Sea MusselLinnaeusPreferred common name. . . Bay mussel Umbo at extreme anterior end of(Figure 1B) shell. Shell covered with a heavy,Other common names . . .Edible mussel, black periostracum. Older specimens,black mussel, blue mussel, pile mussel from which this covering is worn off,

are blue and have an erodedGeographic range: The California sea appearance. Exterior of shell with

mussel ranges from the Aleutian radiating ridges and concentric growth01

CAPE MENDOCINO

BA Y

SAN ~ ~ ~ SAT BANCSCRBYBNARACIC

WHUS Wlls 1

KIOOMERER

Figure~ ~ ~ ~~~~B 2. Catldsrbto fteClfonasamse n a usli

CaCALfFORNIA

PACIFI OCEA

lines. Interior of shell bluish-black for mussels. Piers, floating marinas,iridescence shows in reflected light. jetties, and pilings for oil rigs areLength to 25 cm. Differs from the bay examples of surfaces ideal formussel in having up to a dozen broad settling mussels. In fact, inradial ribs (Fitch 1953). Humboldt Bay, California, the only

substantial population of M. edulisBay Mussel occurs on the under surfaces-of T-oats

in a newly constructed marina.Shell wedge-shaped, with umbos at

extreme anterior tip. Periostracumusually heavy, smooth, satiny black. LIFE HISTORYInterior of shell smooth, blue-blackaround margin, and showing some Spawningiridescence in reflected light. Flesha dull brownish-orange. Length to 10 The California sea musselcm. Differs from the California sea continually spawns throughout the yearmussel partly in having a smooth exte- at a very low level (Suchanek 1981),rior unmarked by radiating ridges and with breeding peaks in July andgrooves (Fitch 1953). December (Morris et al. 1980). In

northern California, Edwards (1984)found no definite spawning cycle.

REASONS FOR INCLUSION IN SERIES Ripe mussels were seen from Februaryto May and from December to February.

The California sea and bay Spawning was observed in January,mussels are relatively common along February, May, and December.the rocky coastline and in bays andestuaries. They support a small The bay mussel has a singlecommercial bait fishery and are massive spawning output each yearcultured for food on a small scale in (Suchanek 1981) which can occur inTomales Bay and just north of San late fall and/or winter along theDiego. central California coast (Morris et

al. 1980). In northern CaliforniaThe areas of greatest potential spawning was first observed in May and

for the commercial harvest of M. again from July through Novemberedulis in California for food, Tn (Edwards 1984).descending order of importance, areHumboldt Bay, Tomales Bay, DrakesEstero, San Francisco Bay, Elkhorn In the laboratory, spawning hasSlough, Morro Bay, San Diego Bay, and been stimulated by raising andTijuana Bay (Chalfant et al. 1980). lowering the water temperature, adding

single cell algae, using water treatedMussels are an important food with ultraviolet light, adding mussel

item throughout the world. There is a sperm, and using water containingpotential for culturing both of these hydrogen peroxide. Breese et al.species for food more extensively in (1963) found 4% Kraft mill effluent toCalifornia. Problems associated with be a highly effective stimulus insuch culturing are seasonal closures triggering mussel spawning. In thecaused by pollution and paralytic natural environment, temperature doesshellfish poisoning (PSP), finding not seem to provide a major stimulusappropriate culture sites, and for spawning. Mechanical stimuli,obtaining public acceptance to use such as pulling on the byssal threads,these sites. may initiate the release of gametes.

Also, spawning of one animal mayMan's manipulation of the coastal stimulate others to spawn (Morris et

zone could provide additional habitats al. 1980).03

During spawning the eggs and 1964). Density of newly settled M.sperm are discharged through the californianus was highest on fila-excurrent chamber. The eggs, which mentous algae (Peterson 1984). Theappear as orange ribbons, are author observed in the laboratory thatfertilized in the open water. M. edulis larvae avoided adult M.

caliTornianus. Investigators disagreeLarval Stage about settling behavior. For example,

the presence of adult M. edulis mayThe embryos develop into inhibit larval settlement. S eedmus-

trochophore larvae (60-80 micrometers) sels appear to set elsewhere, and thenabout 24 h after fertilization. The migrate to adult beds, where theyveliger (straight-hinge stage) devel- attach to byssal threads of the adultsops 24 h later (Figure 3A). A wherever there is space (Jamieson etciliated velum forms and helps the al. 1975). M. californianus preferredlarva swim and maintain itself in the to set on byssal threads from adultswater column. Larvae feed on (Trevelyan and Chang 1983).phytoplankton and are about 0.17 mmlong after 1 week. The veliger, which In southern California M. edulisdevelops an umbo, may reach a length settles in massive numbers in someof 0.20 to 0.24 mm in 2 weeks. years, but sparsely in others (MorrisLoosanoff and Davis (1963) found t.at et al. 1980). In areas where boththe size of mussel larvae (M. edulis) species have settled, M. edulis wasat metamorphosis varied by aimost 0.09 the more mobile and was generallymm; lengths ranged from 0.21 mm to found on the outer part of the col-almost 0.30 mm in length (Figure 3K). onies. It was also more susceptibleJust before metamorphosis, the larva to wave action. Mytilus californianusdevelops an eyespot and foot. holds its position more strongly than

does M. edulis (Harger 1970a).The larvae of M. californianus

have been reared in fthe laboratory to Chalfant et al. (1980) statedmetamorphosis in 17-24 days after that settlement of M. edulis wasfertilization. Eyespots were observed generally gregarious; -in Maine, forwhen the larvae were 0.23 to 0.24 mm example, mussel 2 spat densitieslong (Skidmore and Chew 1985). exceeding 300,000/m have been found

in shallow, subtidal areas.Breeding success or failure is

frequently determined during the The cleaning of surface areascritical larval stage. The larvae are ("brushing the flats") has increasedat the mercy of currents and may be recruitment. Also, the placement ofcarried away from setting areas and pilings, stakes, or poles is a commondie. commercial method of collecting seed

mussels. In the Santa BarbaraPostlarvae and Recruitment Channel, natural sets of M.

californianus are collected from theMytilus edulis sets on the byssal legs of oil drilling platforms.

threads of adults, on a variety of Setting areas are prepared by cleaningalgae, and on newly exposed hard unwanted growth or wrapping areas withsurfaces; M. californianus sets on special materials that attract wildbarnacles, old mussel shell, and newly spat.exposed hard surfaces (Petraites1978). In California, M. edulissettled immediately on scraped, bare It probably takes many years forsubstrate (i.e. no succession Mytilus to become established in theoccurred) in winter and spring; it did high intertidal zone at approximatelynot settle in summer and fall (Reish +1.8 to +2.4 m above mean lower low

4

AB C D93x65 110X82 125 x98 139 x116

E F GH152x129 170 x149 1900166 215xZOI

K

232X210 260x247 296X282

MYTILUS EDULISX 112

Figure 3. Larval development of the bay mussel, size (height and length) inmicrometers.

0 5

water (Dayton 1971). Establishment is seriously decreased growth, but alsofaster at lower levels (Dayton 1971). caused mortalities of 89%-100%.

Maturity In extensive growth studiesconducted in Puget Sound, Washington,

Sex ratios are generally equal by Skidmore and Chew (1985), sets ofand there is no indication of sex M. edulis in four of five experimentschange with age. Some sexually mature attained market size (50 mm) within 12mussels were only 4 months old or 25 to 13 months. The growth rates of M.mm long. Viable sperm was observed in edulis and M. californianus were alsomussels 30 mm long. Spawning occurred compared at two sites in Puget Sound.near the end of the first year or when Mytilus edulis grew the fastest forthe mussels were 70 mm long (Coe and the first three months, but sizeFox 1942). differences between the two species

were small by the end of 9 months.Age and Growth

In southern California (ScrippsThe age of mollusks is determined Institution of Oceanography dock, San

by three methods: (1) size-frequency Diego) M. californianus sometimesstudies; (2) the interpretation of grows as much as 7 mm per month. Thisgrowth interruption lines on the species may reach a length of 80-86 mmshell; and (3) experimental methods within a year of settlement, 120 mminvolving the release and recovery of after 2 years, and 140-150 mm after 3marked individuals (Haskin 1954). years (Coe and Fox 1942). MaximumJamieson et al. (1975) reported that size is 200-250 mm (Harger 1972).growth rates of mussels in any given Growth is fastest during the colderpopulation were so variable that year months and slowest (sometimes nil) inclasses could not be determined from mid-summer or above 20 C.size. Most workers have attempted toage mussels through interpretation of Mytilus edulis does not grow asgrowth interruption lines, although large as M. californianus (Figure 4).some have studied marked individuals. In southern California, the bay musselLutz (1976) aged mussels by using grew to a length of 66 to 76 mm afteracetate on polished longitudinal shell 1 year and 90-99 mm after 2 years (Coesections. 1945). Thereafter, growth was very

slow (Table 1). Maximum size rangesFactors influencing growth of M. from 120-150 mm (Harger 1972).

edulis were divided into twocategories by Jamieson et al. (1975): Mussels eat a variety ofbiological (age, size, and genotype), organisms, such as dinoflagellates,and physical (light, temperature, organic particles, small diatoms,depth, food, salinity, and current). zoospores, minute ova and spermatozoa,Of these, water temperature was the flagellates and other protozoans,only factor which influenced growth various unicellular algae, andthroughout the mussel's geographic detritus (consisting of particles fromrange. In some areas (e.g., Maine), the cytolysis of cells of a largegrowth was seasonal, whereas in variety of plants and animals).California, where the annual Growth rates are related to thetemperature range was relatively abundance of dinoflagellates (Coe andnarrow, there was no obvious seasonal Fox 1942). Mytilus californianus fromvariation in shell growth rate southern California grew I00 faster(Chalfant et al. 1980). Lutz and in height and 50% faster in width atPorter (1977) reported that water +0.1 m (the plus sign in this reporttemperature above 25 C not only indicates vertical height above mean

6

0Q COMMERCIAL AND SPORT FISHERIES ANDAQUACULTURE

Both species of mussels were oncecommercially important in California.Over 69,000 pounds were landed in

4 1917 (Table 2), but in 1927, andthereafter, most areas were closed to

4' fishing by the California State Board1 4 of Health, due to mussel poisoning.,... "...No mussels can now be sold for human

Figure 4. Projected growth curves for consumption from May 1 to October 31Mytilus edulis (open symbols) and because of the presence of paralyticMYtus ca--fo'rnianus (closed symbols) shellfish poisoning. The consumptionbased on data obtained from of mussels that have concentratedundisturbed populations of mussels at large amounts of the poison-producingSanta Barbara Harbor, California microscopic dinoflagellate Gonyaulax(Harger 1970b). catenella sometimes causes serious

illness (Nishitani and Chew 1983). In1980, for example, poisoning was

lower low water) than at +0.3 m where recorded in 98 residents of Matin andfeeding time was shorter (Dehnel Sonoma counties, California, of whom1956). Males grow faster than females two died (Estes and VanBlaricom 1985).the first 1.5 years (Coe and Fox1942). A limited sport fishery, where

mussels are usually removed fromFood particles, drawn through an piling or rocks by hand, now exists

inhalent aperture by ciliary action, during the open season. A dailyare caught on sheets of mucus and harvest of 25 pounds is allowed.carried along the sides of palps tothe mouth. Some particles are Four companies have showningested but others, if excessive, are interest in farming mussels for humandischarged from the mantle cavity as consumption in Tomales Bay, Cali-pseudofeces. The most common food is fornia, because the demand for a year-the dinoflagellate Prorocentrum round supply of quality mussels hasmicans, at a size of 57 x 30 pm (Fox outgrown the supply from native beds.and Coe 1943). They hang ropes from longlines

supported by floats to collect anatural set. The seed is then placed

Tatle 1. Growth of Mytius edulis in in plastic netting, which is then hungrelation to size (Coe14 3. from the longlines.

One company cultures mussels fromAverage increase the legs of oil drilling platforms in

Size (mm) per month (mm) the Santa Barbara channels. Seed,placed in plastic netting, is wrappedaround the legs. When the mussels

11-20 11.3 reach maturity divers scrape them off21-30 11.1 the legs. The mussels are conveyed to31-40 9.9 the surface through suction hoses and41-50 8.0 are cleaned, packaged, and shipped51-60 5.9 fresh to market.61-90 2.891-103 0.75 The ratio of meat to total weight

is high in mussels. The composition

07

Table 2. Yearly landings of mussels crude fat, 2.6%-3.5%; ash, 2.0%-2.7%;in California. and carbohydrate, 1.2%-5.8%.

LandingsYear (lb) ECOLOGICAL ROLE

1916 a 53,799 Feeding1917 69,0421918 49,154 Mussels are suspension feeders,1919 35,095 are considered to be scavengers, and1920 33,112 collect anything in the plankton that1921 9,196 is small enough to ingest. Digestion1922 43,872 is intracellular (Coe and Fox 1944).1923 60,0261924 49,223 Competitors1925 25,9421926 14,614 When a resource is potentially1927 29,631 limiting (as in the case of living1928 1,610 space for sessile organisms in the1929 1,028 rocky intertidal zone) one species of1930 325 competitor may potentially dominate1931 1,800 the others in procuring or holding the1932 230 resource. Predation or physical1933 465 disturbance may cause mortality of the1935 10 dominant competitor sufficient to1936 750 prevent the exclusion of the other1937 1,490 competitors, allowing several species1938 150 to coexist. Such phenomena occur in1939 1,800 the rocky intertidal zone of the1940 100 Pacific coast of the United States,1942 50 where significant insights into such1946 639 processes of community function have19470 530 been obtained especially from studies1972 d111,7999 done on the coast of Washington. As19740e 81,6429 shown in the following discussion, the1975 53,6919 distribution of M. californianus isf h1976 47,336 controlled by predation and physical

disturbance, while the distribution ofaYears 1916-1947 (Bureau of Marine M. edulis is controlled by these twobFisheries 1949). factors and competition as well.No commercial landings between 1948-1971. On Washington's exposed outer

cPinkas 1974. coast, M. californianus is thedMcAllister 1976. dominant competitor for available

fPinkas 1977. space and will form dense monospecificOliphant 1979. stands unless deterred (Paine 1966).

gBait. Mytilus californianus is one of the2,357 pounds for human consumption; most consistent occupants of space inrest for bait. the intertidal barnacle-mussel

association there, along with thebarnacles Chthamalus dalli, Balanusglandula, and B. cariosa, and the sea

of cultured M. edulis, analyzed by anemone Anthopleura elegantissimaSlabyj et a. (T7)-, is moisture, (Dayton 1971). The name Cal ornia71.1%-75.7%; protein, 14.1%-21.0%; sea mussel" was given to M.

8

californianus because of its californianus (Dayton 1971), one ofrestriction mostly to the outer coast. its preferred prey (Paine 1966). InMytilus californianus will settle an experiment in Washington, P.among Balanus and completely cover the ochraceus was removed and the areabarnacles (Dayton 1971), eventually eventually became a monospecific standexcluding them (Paine 1966). Mytilus of M. californianus (Paine 1966).californianus denies space to M. Pisaster ochraceus controls theedulis on the open coast, but it seems abundance of the dominant mussel andto offer protection from wave action thus allows other species to coexistto those M. edulis that do become (Paine 1966). Mytilus californianusattached Harger T970c). lus escapes predation from whelk predatorsedulis is called the "bay mussel" (Thais spp.) by attaining a variablebecause it has long been thought to be minimum size of invulnerabilitycommon mostly in quiet waters, but it (Dayton 1971). This mussel escapesis now known to be common on the outer pr -ation by P. ochraceus by growingcoast as well (Suchanek 1978). to a minimum size that increases asMytilus edulis on the exposed outer the size of the sea star increasescoast of Washington usually occupies a (Paine 1976b). Mean density of P.band 0.3 m in vertical height (at ochraceus may vary locally by at leastabout +2.9 to +3.2 m) above the M. two orders of magnitude, affectingcalifornianus zone, which is at about local abundance of M. californianus+0.5 to +2.9 m (Suchanek 1978). The (Paine 1976b). In Washington, areaslower limit of M. edulis zone is of low M. californianus abundance andprobably set by competitive exclusion high P. ochraceus density occur side-by M. californianus and by predation by-side with dense stands of large M.(Su-hanek 1978). californianus that have low P.

ochraceus density; the mussels hadPredators probably escaped predation by

attaining an invulnerable size (PaineA number of predators prey on 1976b).

mussels in California. Harger (1972a)reported that M. edulis was preferred Pisaster ochraceus may indirectlyover M. californianus by nine enhance recruitment of M.invertebrate predators: two sea stars, californianus by the following seriesPisaster giganteus and P. ochraceus, of events: 1) P. ochraceus consumesfive species of murici{ gastropods, limpets (less priferred prey) and mayThais emarginata, Acanthina spirata, reduce their abundance; 2) as shownOce-nebra poulsoni, Ceratostoma experimentally, a reduction in limpetnuttalli, and Jaton festivus, and two density would consequently enhance thespecies of crabs, Cancer antennarius abundance of one of the limpet's majorand Pachygrapus crassipes. A third foods, the red alga Endocladia; andcrab, Pugettia producta, ate mussels 3) mussel recruitment may be enhancedbut showed no preference for a 1.,cause Endocladia is the majorparticular species. Harger and settling substrate for M.Landenberger (1971) observed greater californianus larvae (Dayton 1971).losses from predation in shallow watercompared to deep water. On the outer coast of Washington,

M. edulis will become established in aMytilus californianus occupies patch cleared by physical disturbance

only about 4% of the space (between or predation in the M. californianusabout +3 m and a depth of about -27 m) zone (which is at about +0.5 tothat it would occupy under physically +2.9 m) only if the patch diameter ismild and predator-free conditions greater than about 40 cm (Suchanek(Paine 1976b). The sea star P. 1978). Smaller patches exposeochraceus may clear patches of I. settling M. edulis (and the

9

filamentous algae used as settling mussel and swallow it whole. Thesubstrate) to removal by grazers other mussels in the clump sink to the(limpets, chitons, and the bottom (Skidmore and Chew 1985).opisthobranch gastropod Onchidellaborealis) that move in from the edgeof the patch (Suchanek 1978). Those Commensals, Parasites, and EncrustingM. edulis that do invade the M. Epifaunacalifornia us zone grow quickly butare preferred over M. californianus by The commensal crab, Pinnothereswhelk predators, Thais spp. (Suchanek sp., has been found in M. edulis. The1978). On the outer coast, the lower crabs eat the food mussefs havelimit of M. edulis band (about +2.9 m) filtered out and decrease the pumpingis probably determined partly by rates of mussels. Mature female crabspredation by gastropods, birds, and can reduce the meat yield by as muchsea stars (Suchanek 1978). Pisaster as 26% (Pregenzer 1981).ochraceus has more time to feed andthus can eat more mussels at lower In California the parasiticintertidal levels. The abrupt lower copepod Mytilicola orientales waslimit of M. californianus band (about found in 13 of 20 M. californianus and+0.5 m) is almost certainly the most in 24 M. edulis (Chew et al. 1964)conspicuous feature of the rocky Bradley and Siebert (1978) foundintertidal community (Paine 1976) and Mytilicola in M. edulis from Sanis probably set by predation by P. Francisco Bay (iiidence range, 36.8%-ochraceus (Paine 1966, 1974). 48.5%); they believed the parasite was

imported with the Japanese oysterThe sea otter (Enhydra lutris) is (Crassostrea igas). The gonads of

known to eat both M. californianus and one M. californianus, from HumboldtM. edulis (Estes and Van8laricom Bay, were heavily parasitized withT985), but mussels form only a small trematode cercariae of the familyportion of its diet in California. Bucephalidae (Edwards 1984), andConsumption of mussels by sea otters trematode sporocysts were found in theappears to be sufficiently scattered digestive gland and gonadal tissue ofin time and space to preclude the M. edulis (Brousseau 1983).regional depletion of harvestablestocks. The exposure of much of the Subtidal M. californianus may becentral California coast to heavy surf overgrown by sponges, barnacles,probably provides an important refuge anemones, and other epifauna (Painefor mussels from foraging sea otters. 1976a). Heavily encrusted musselsPredation by the black oystercatcher, weighed less (in tissue weight) thanHaematopus bachmani, and dislodgement those less encrusted (Paine 1976a).by storm waves are probably at leastas important as sea otter predation inlimiting the availability of mussels ENVIRONMENTAL REQUIREMENTSfor human consumption in California.

Temperature and SalinityDiving ducks, especially scoters,

are mussel predators. Three species Temperature plays an importantof ducks are responsible for most of role in growth. Coe and Fox (1944)the losses--the surf scoter, Melanitta found that the growth of M.delgandi, white-winged scoter, M. californianus was most rapid at 17410perspicillata, and black scoter, "C and decreased sharply above 20 0C.Oidemia amereicana. In feeding, the Growth sontinued (but at a lower rate)TucE-dive underwater, remove a clump at 14 C or lower but less rapidly.of mussels, return to the surface, Feeding continued at 7-8 OC anshake the clump, and dislodge one 27-28 *C. Filtration rate and oxygen

10

consumption were highest at 20 0C (Coe edulis needs to be submerged at leastand Fox 1942). half the time to show significant

growth.In California the optimum temper-

ature range for growth was 10-20 cC(Morris et al. 1980). Feldmeth and Physical DisturbanceAlpert (1977) found that the mean wetweight of mussels from the cooler Wave action or wave-borne logs inwaters of Alamitos Bay, California exposed areas may remove whole mats of(14.8-15.8 C) was four times greater mussels in the intertidal zone (Daytonthan those from San Gabriel River 1971). At the edge of a cleared(22.7-25.0 C). patch, substantial numbers of

additional mussels may be removed byIn nature, M. californianus is wave action (Dayton 1971). Mussels

rarely found in 5ays and estuaries-- high in the intertidal zone away fromperhaps because eggs, sperm, and starfish predation may survive for alarvae cannot withstand dilutions great many years, until some arebelow 75% sea water (Robertson 1964). killed by wave-borne logs, unusualIn contrast, M. edulis can accommodate cold, or other physical stressesa wide salinity range (Bayne 1965)--an (Dayton 1971). The upper limit to theinterspecies difference that explains M. edulis zone in the high intertidalits wider distribution both in the area at Tatoosh Island, Washington,open coastal waters and in protective was controlled by extreme summer heatbays. that killed mussels, or made their

shells gape and made them easy preyHabitat for gulls (Suchanek 1978).

Mytilus edulis is sensitive tothe e ofc7 waves (Harger 1970a). Other Environmental FactorsIt appears that M. californianus holdsits position more strongly than does Because mussels--particularly M.M. edulis. edulis--are distributed along the

coast, and in bays and estuaries, theyMytilus edulis is behaviorally are often subjected to sewage and

adapted to quiet waters better than M. other kinds of pollution (Robertscalifornianus. Mussels may form 1976). The mussels may be unsafe toclumps up to 25 cm thick; juvenile M. eat and must be depurated beforeedulis crawl to the outside of such marketing. In addition, both speciesclumps which may include M. of mussels ingest certain dinofla-californianus, but the latter mussel gellates that make them toxic todoes not (Harger 1968). This crawling humans, causing paralytic shellfishbehavior protects M. edulis from poisoning.harmful silt that accumulates insidethe clumps in quiet waters. This silt Mussels concentrate hydrocarbonsmay tend to exclude M. californianus in their tissues. The hydrocarbonsthere (Harger 1968). are rapidly taken up by the gill

tissues and eventually are depositedThe growth of M. edulis was in high concentrations in the

seriously affected by tidal exposure. alimentary canal (Roberts 1976).Little or no growth took place at 80% Although oil is only slightly toxic toexposure and the mussels died within 3 mussels, it may affect the marketingmonths; growth was significantly less of the animals by tainting them.at 40% and 60% exposure than at 0% and Clark and Finley (1975) reported that20% exposure (Christensk,n 1984). the uptake and loss of petroleumMorris et al. (1980) stated that M. hydrocarbons was related to the

h 11

magnitude of exposure. When mussels Since 1977 the Californiawere placed in clean water, most Department of Fish and Game has beenhydrocarbons were lost but significant monitoring the amount of trace metalsquantities of No. 2 fuel oil remained in mussels (State Mussel Watch) alongfor as long as 35 days. Fuel oil and the coast (Stephenson et al. 1980a,outboard motor oil may inhibit byssal 1980b). Of the sites investigated,thread formation but at Long Beach Royal Palms, Corona del Mar, and LaHarbor, California, motor boat Jolla were "hot spots" for silver,activity posed little threat (Carr and copper, lead, and zinc. Silver wasReish 1978). especially high in mussels in South

San Francisco Bay. Los Angeles Harborand Santa Catalina Island had the

A number of trace metals are highest concentration of silver andfound in the soft tissues of mussels, lead while mussels in San Diego hadincluding Ag, Cu, Cr, Mn, Pb, Cd, and the highest concentration of zinc.Zn. Levels in M. edulis from The amount of trace metals in mussels,California (Table 3) agreed with those depending on site, were in manyof the same species in New Zealand instances much higher than those found(Graham 1972). by Graham (1972).

Table 3. Dry weight (ppm) of trace metals in soft parts of whole bodies ofMytilus edulis. Values are approximate means (ranges in parentheses) (Graham197-2).

Location N Ag Cu Cr Mn Pb Cd Zn

California 24 1 7 4 16 5 5 284(<1-1.3) (5-11) (<2-8) (6-28) (2-8) (3-7) (204-341)

NewZealand 6 1 9 16 27 12 1 91

(0.1-1.3) (8-11) (9-24) (12-38) (3-25) (1 (50-180)

12

LITERATURE CITED

Bayne, B.L. 1965. Growth and delay R.A. Lutz, ed. Mussel culture andmetamorphosis of the larvae of harvest: A North AmericanMytilus edulis (L). Ophelia 2(1):1- perspective. Elsevier Scientific47. Publishing Company, Amsterdam.

Bradley, W., and A.E. Siebert, Jr. Chew, K.K., A.K. Sparks, and S.C.1978. Infection of Ostrea lurida Katkansky. 1964. First record ofand Mytilus edulis by the parasite Mytilicola orientalis Mori in thecopepod Mytilicola orientalis in San California mussel Mytilus edulisFrancisco Bay, California. Veliger Conrad. J. Fish. Res. Board Can.21(1): 131-134. 21(1):205-207.

Breese, W.P., R.E. Millemann, and R.E. Christensen, F.W. 1984. IntertidalDimick. 1963. Stimulation of growth response of Mytilus edulisspawning in the mussel Mytilus (Linnaeus) in Humboldt Bay, Cali-edulis Linnaeus and Mytilus fornia. M.S. Thesis. Humboldtcalifornianus. Biol. Bull. (Wood-s State University, Arcata. 35 pp.Hole) 125(2):197-205.

Clark, R.C. Jr., and J.S. Finley.Brousseau, D.J. 1983. Aspects of 1975. Uptake and loss of petroleumreproduction of the blue mussel, hydrocarbons by mussels, MytilusMytilus edulis (Pelecypoda: edulis, in laboratory experiments.Mytilidae) in Long Island Sound. U.S. Natl. Mar. Fish. Serv. FishU.S. Natl. Mar. Fish Serv. Bull. Bull. 73(3):508-515.81(4):733-739.

Coe, W.R. 1945. Nutrition and growthCalifornia Bureau of Marine Fisheries. of the California bay-mussel

1949. The commercial fish catch of (Mytilus edulis diegensis) J. Exp.California for the year 1947 with an Zool. 99(I1-1T4.historical review 1916-1947. Calif.Dep. Fish Game Fish. Bull. 74. 267 Coe, W.R., and D.L. Fox. 1942.pp. Biology of the California sea-mussel

(Mytilus californianus). I.Carr, R.S., and D.J. Reish. 1978. Influence of temperature, food

Studies on the Mytilus edulis supply, sex and age in the rate ofcommunity in Alamitos Bay, Calif- growth. J. Exp. Zool. 90(1):1-30.ornia: VII. The influence of water-soluble petroleum hydrocarbons on Coe, W.R., and D.L. Fox. 1944.byssal thread formation. Veliger Biology of the California sea-mussel21(2):283-287. (Mytilus californianus). III.

Environmental conditions and rate ofChalfant, J.S., Jr., T. Archambault, growth. Biol. Bull. (Woods Hole)

and A.E. West, J.G. Riley, and N. 87(l):59-72.Smith. 1980. Natural stocks ofmussels: growth, recruitment and Dayton, P.K. 1971. Competition,harvest potential. Pages 36-68 in disturbance, and community organ-

13

ization: the provision and sub- biology of sea mussels. Veliger

sequent utilization of space in a 12(4):401414.rocky intertidal community. Ecol. Harger, J.R.E. 1970b. ComparisonMonogr. 41(4):351-389. among growth characteristics of two

Dehnel, P.A. 1956. Growth rates in species of sea mussels, Mytilus

latitudinally and vertically edulis and Mttls californianus.

separated populations of Mytilus Veliger 13(1): .

californianus. Biol. Bull. 1:43 Harger, J.R.E. 1970c. The effect ofspecies composition on the survival

Edwards, R.L. 1984. The reproductive of mixed populations of the sea

and percentage solids cycles of mussels, Mytilus californianus andMytilus edulis and ytilus Mytilus edulis. Veliger 13(2):147-

californianus in Humboldt County, 152.

California. M.S. Thesis. HumboldtState University, Arcata. 57 pp. Harger, J.R.E. 1972. Competitivecoexistence: maintenance of

Estes, J.A., and G.R. VanBlaricom. interacting associations of the sea

1985. Sea-otters and shell- mussels Mytilus edulis and Mytilus

fisheries. Pages 187-235 in J.R. californianus. Veliger 14(4):387-

Beddington, R.J.H. Beverton, andD.M. Lavigne, eds. Marine Mammalsand Fisheries. George Allen and Harger, J.R.E., and D.E. Landenberger.Unwin, London. 1971. The effect of storms as a

density dependent mortality factorFeldmeth, C.R., and M. Alpert. 1977. on populations of sea mussels.

The effect of temperature on the Veliger 14(2):195-201.distribution and biomass of Mytilusedulis in the Alamitos Bay area. Haskin, H.H. 1954. Age determinationVeTiger 20(1):39-42. in mollusks. Trans. N.Y. Acad. Sci.

16:300-304.Fitch, J.E. 1953. Common marinebivalves of California. Calif. Dep. Jamieson, G.S., I.C. Neish, and C.S.L.Fish Game Fish. Bull. 90. 102 pp. Clark. 1975. Perspective and devel-

opment prospects of mussel cultiva-Fox, D.L., and W.R. Coe. 1943. tion in the Maritime Provinces ofBiology of the California sea-mussel Canada. Mar. Ecol. Lab. Nova(Mytilus californianus) II. Scotia. Ref. AMRL74-11. 75 pp.Nutrition, metabolism, growth andcalcium deposition. J. Exp. Zool., Loosanoff, V.L., and H.C. Davis.93:205-249. 1963. Rearing of bivalve mollusks.

Advances in Marine Biology 1:1-136.Graham, D.L. 1972. Trace metal

levels in intertidal mollusks of Lutz, R.A. 1976. Annual growthCalifornia. Veliger 14(4):365-372. patterns in the inner shell layer of

Mytilus edulis L. J. Mar. Biol.Harger, J.R.E. 1968. The role of As .. .3TV7h73-731.

behavioral traits in influencing thedistribution of two species of sea Lutz, R.A., and B. Porter. 1977.mussel, Mytilus edulis and M. Experimental culture of blue musselscalifornianus. Veliger 1-(1):45-49. Mytilus edulls in heated effluent

waters of a nuclear power plant.Harger, J.R.E. 1970a. The effect of Proc. World Maricult. Soc. 8:427-

wave impact on some aspects of the 445.

14

McAllister, R. 1976. California Pinkas, L. 1974. California marinemarine fish landings for 1974. fish landings for 1972. Calif. FishCalif. Fish Game Fish Bull. 166. 53 Game Fish. Bull. 161. 53 pp.Pp.

Pinkas. L. 1977. California marinefish landings for 1975. Calif. Fish

Morris, R.H., D.P. Abbot, and E.C. Game Fish Bull. 168. 55 pp.Haderlie. 1980. Intertidal inver-tebrates of California. Stanford Pregenzer, C.L. 1981. The effect ofUniversity, Stanford, California. Pinnotheres hickmani on the meat690 pp. yield (condit5n ofMytilus edulis

measured several ways. VeligerNishitani, L., and K.K. Chew. 1983. 23(3):250-253.Gathering safe shellfish inWashington. Wash. Sea Grant Program Reish, D.J. 1964. Studies on theAdvis. Rep. WSG-RF82-3: 6 pp. Mytilus edulis community in

Atlanitos Bay, California: I.Oliphant, M.S. 1979. California Development and destruction of themarine fish landings for 1976. community. Veliger 6(3):124-131.Calif. Fish Game Fish Bull. 170.56 pp.

Roberts, D. 1976. Mussels and pollu-Paine, R.T. 1966. Food web complex- tion. Pages 67-80 in B.L. Bayne, ed.

ity and species diversity. Am. Nat. Marine mussels, ft-eir ecology and100:65-75. physiology. Cambridge University

Press, Cambridge.Paine, R.T. 1974. Intertidal commu-

nity structure. Experimental stud- Robertson, J.D. 1964. Osmotic andies on the relationship between a ionic regulation. Pages 283-311 indominant competitor and its princi- Karl M. Wilbur and C.M. Yonge.pal predator. Oecologia 15:93-120. Physiology of mollusca, Volume 1.

Academic Press, New York.

Paine, R.T. 1976a. Biological Skidmore, D., and K.K. Chew. 1985.observations on a subtidal Mytilus Mussel aquaculture in Puget Sound.californianus bed. Veliger 19(2): Wash. Sea Grant Program, WSG 85-4.125-130. 57 pp.

Paine, R.T. 1976b. Size-limited Slabyj, B.M., D.L. Creamer, and R.H.predation: an observational and True. 1978. Seasonal effects onexperimental approach with the yield, proximate composition andM -tilus-Pisaster interaction. Ecol- quality of blue mussels (Mytilus

oy57:858-873. edulis) meats obtainedctivated and natural stocks. Mar.

Petersen, J.H. 1984. Larval settle- Fish Rev. 40(8):18-23.ment behavior in competing species:Mytilus californianus and M. edulis. Stephenson, M.D., M. Martin, and J.H.J.Exp. Mar. Biol. Ecol. 87:1477M. Martin. 1980a. Trace metal concen-

trations in mussels from bays inCalifornia. State mussel watch -Volume IV. California Water Quality

Petraitis, P.S. 1978. Distribution Rep. No. 79-22. 56 pp.patterns of juvenile Mytilus edulisand Mytilus californianus. Veliger Stephenson, M.D., S.L. Coale, M.21(2):288-291. Martin, and J.H. Martin. 1980b.

0l i15

California mussel watch 1979-1980. Suchanek, T.H. 1981. The role ofTrace metal concentrations in the disturbance in the evolution of lifeCalifornia mussel, Mytilus history strategies in the intertidalcalifornianus, and bay mussel, M. mussels Mytilus edulis and Mytjjusedulis, along the California coast californianus. Oecologia (Berl.).and selected harbors and bays. Part 50:143-152.I. California Water QualityMonitoring Rep. 80-8. 95 pp.

Trevelyan, G.A., and E.S. Chang.Suchanek, T.J. 1978. The ecology of 1983. Experiments on larval rearing

Mytilus edulis L. in exposed rocky of the California mussel (Mytilusintertidal communities. J. Exp. californianus). J. World Maricult.Mar. Biol. Ecol. 31:105-120. Soc. 14:137-148.

16

REPORT DOCUMENTATION L moMT NO. j2. L 4 , .. . .. ....PAGE ioloagical Report 82(11.84]*I

4. TWO* *fW Sw614"s IL ft"" DaeSpecies Profiles: Life Histories and Environmental September 1988Requirements of Coastal Fishes and Invertebrates L(Pacific Southwest)--California sea mussel and bay mussel

7. A.thO.() L Pwlo-mg 0,go..sot~o. P.& ft

aWilliam N. Shaw, bThomas J. Hassler, and CDavid P. Moran. Pod d n g Ogolastehe No-. *nd Add,*%*aHumboldt State University bU.S. Fish & Wildl. Ser. CU.S. Fish and Wildlife Service

Department of Fisheries Calif. Coop. Fishery Unit National Wetlands Research CenterFred Telonicher Marine Lab. Humboldt State University 1010 Gause BoulevardTrinidad, CA 95570 Arcata, CA 95521 Slidell, LA 70458

I2. 3" o On g noizetlen No-* .nd Add .,

U.S. Department of the Interior U.S. Army Corps of Engineers ILType ofX.Pon L F*odCo-.d

Fish and Wildlife Service Waterways Experiment StationResearch and Development P.O. Box 631National Wetlands Research Center Vicksburg, MS 39180 1

Washington, DC 20240

IL Supplementary Notes

*U.S. Army Corps of Engineers Report No. TR EL-82-4

-11. Abstrm¢ (Umit 200 wds)

__.Species profiles are literature summaries of the taxonomy, morphology, distribution, lifehistory, and environmental requirements of coastal aquatic species. They are preparedto assist in environmental impact assessment. The California sea mussel, Mytiluscalifornianus, and the bay mussel, M. edulis, are commonly collected for bait. Somecommercial landing and aquaculture occurs at a very low level of production. Bothspecies are distributed along the California coast; the sea mussel is more commonlyfound on intertidal coastal rocks and the bay mussel on pilings and other hard substratesin bays and estuaries. The eggs of both soecies develop into a trochophore stage in12-24 hours after fertilization, and the planktonic larval stage lasts 3-4 weeks. Sexualmaturity can occur in one year. Spawning of the sea mussel occurs sporadically through-out the year; the bay mussel spawns in central California in late fall and winter.Maximum length is 120-150 mm for the bay mussel and 200-250 mm for the sea mussel. Bothspecies are regarded as unsafe to eat from May 1 to October 31 due to the possiblepresence of paralytic shellfish poisoning.

17. Decumnt Analysis a. ODeetipteos

Life cycles Feeding habits -EstuariesFisheries- Growtn , ,, SalinityMussels Competition TemperatureAquaculture Water pollution -Contaminants

b. Idsn~tf1A*l /.wPCnd.d Tern,-

Bay mussel Ecological roleMytilus edulis Commercial fisheryCa Tonia sea mussel Sport fisheryMytilus californianus Ecological requirements c ->.

c- COSATI rled/Group

IL Aed lsbllity Slleemeng It. Secunty Class (This MemO 21. No. of Pages

Unlimited release Unclassified 16M. Sec~uslty class MIS Page) 2. Price

Unclassified;S.. ANSI-Z.39.|I) OPTIONAL OAU 272 (4-1 71

tenmern T C.n-3S%oqim f co-~%-e