9
Differences between North Arnerican and European Populations of Balanus balanoides Revealed t y Transplantationl Bv D. J. Cnrse []n,ivers'ity CollegeoJ lVorth Wales Mar'ine Sc,ience Laboratories, Menai Br,id,ge, Anglesey, Wales ABSTRACT Transplants of specimens of Balanus balanoicles from North \Vales to Newfoundland, Canada, confirmed two innate differences between European and North American forms of the species. Breecling took place later in transplanted European populations. The eggs of the European form, though maturing later and therefore at a slightly lower temperature than the North American form, were distinctly smaller. The time of breeding both in the North American arrd European forms was earlier at higher latitudes, at higher shore levels, and in shelter. INTRODUCTION TnB enBBnINGsEASoN of several population of tl-re circumboreal Arctic species Balanus balanoides from different localities betrveen latitudes 40o and 45oN on the North American side of the Atlantic has been given by Barnes (1958) and may be cornpared with that of populations of the same species from a wider latitudinal range on the coast of Europe, extending from Northern Norway to southwest England (Crisp, 1959a). if the populations studied can be regarded as representative of those throughout the European and North American sides of the Atlantic Ocean, there appear to be minor, but significant, differences in reproductive physiology in these morphologically indistinguishable races. The North American race not only breeds earlier at corresponding latitudes, but its embryos develop more rapidly at the same temperature, and its eggs are significantly larger. The differencesl'vere retained at least for a year after transplantation from North America to Europe, and were therefore thought likely to be innate (Crisp, 196+). Further observations have nor,v been made on breeding in this species over a rvider latitudinal range on the North American coast, and an exper- imental population rvas transferred in the reverse direction, from Britain to Newfoundland, to compare the reproductive cycle of the t$'o races under identical climatic conditions. METHODS Specimens oI B. balanoides attached to mussel shells were sent by air to St. John's, Newfoundland, and transplanted, using quick-setting cement, lReceived for publication March 13, 1968. 2633 J. Frsn. RBs. Bo. CaNro.t, 25(12):2633-2641, 1968. Printed in Canada. J. Fish. Res. Bd. Can. Downloaded from www.nrcresearchpress.com by CONCORDIA UNIV on 11/12/14 For personal use only.

Differences between North American and European Populations of Balanus balanoides Revealed by Transplantation

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Page 1: Differences between North American and European Populations of               Balanus balanoides               Revealed by Transplantation

Differences between North Arnerican and EuropeanPopulations of Balanus balanoides Revealed t y

Transplantationl

Bv D. J . Cnrse

[]n,ivers'ity College oJ lVorth WalesMar'ine Sc,ience Laboratories, Menai Br,id,ge, Anglesey, Wales

ABSTRACT

Transplants of specimens of Balanus balanoicles from North \Vales to Newfoundland,Canada, confirmed two innate differences between European and North American forms ofthe species. Breecling took place later in transplanted European populations. The eggs of theEuropean form, though maturing later and therefore at a slightly lower temperature than theNorth American form, were distinctly smaller.

The time of breeding both in the North American arrd European forms was earlier at higherlatitudes, at higher shore levels, and in shelter.

INTRODUCTION

TnB enBBnING sEASoN of several population of t l-re circumboreal Arctic speciesBalanus balanoides from different localit ies betrveen latitudes 40o and 45oNon the North American side of the Atlantic has been given by Barnes (1958)and may be cornpared with that of populations of the same species from awider latitudinal range on the coast of Europe, extending from NorthernNorway to southwest England (Crisp, 1959a). if the populations studiedcan be regarded as representative of those throughout the European andNorth American sides of the Atlantic Ocean, there appear to be minor, butsignificant, differences in reproductive physiology in these morphologicallyindistinguishable races. The North American race not only breeds earlier atcorresponding latitudes, but its embryos develop more rapidly at the sametemperature, and its eggs are significantly larger. The differences l 'vere retainedat least for a year after transplantation from North America to Europe, andwere therefore thought l ikely to be innate (Crisp, 196+).

Further observations have nor,v been made on breeding in this speciesover a rvider latitudinal range on the North American coast, and an exper-imental population rvas transferred in the reverse direction, from Britain toNewfoundland, to compare the reproductive cycle of the t$'o races underidentical climatic conditions.

METHODS

Specimens oI B. balanoides attached to mussel shells were sent by airto St. John's, Newfoundland, and transplanted, using quick-setting cement,

lReceived for publication March 13, 1968.

2633J. Frsn. RBs. Bo. CaNro.t, 25(12):2633-2641, 1968.Printed in Canada.

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Page 2: Differences between North American and European Populations of               Balanus balanoides               Revealed by Transplantation

2634 JoURNAL FTSHERTES RESEARCH BoARD oF cANADA, vor- .2s, No. 12, 1968

to a position in the normal Balanus zone near, or slightly above, mean tidelevel. A semi-sheltered shore, Horse Cove in Conception Bay, was chosenfor this experiment. Transplantation was completed betrveen August 11 and18, 1962, rvell in advance of the breeding season.

Samples were removed weekly for examination of the reproductive stateduring the period of ferti l isation and oviposition, and thereafter at longerintervals. The percentage carrying ferti l ised egg masses, the stage of em-bryonic development of the eggs, the dimensions of the eggs, and the con-dition of the male reproductive system were noted in each sample.

Corresponding observations were made on samples ol B. balano'idesnative to Newfoundland growing in the same environment as the transplants,and on samples native to Wales grorving at the site from which the transplantshad been collected. Two samples were obtained from Woods Hole, Mass.,during October t962 and rn'ere examined for further comparison; other pop-ulations rvere examined in the field in Nova Scotia during the breeding season.To conform with the Canadian Government's legislation on the introductionof living exotic fish, the transplantation experiment was terminated andall imported barnacles removed on February 10, 1963 before any l iberationof naupli i had taken place.

The samples collected in Nova Scotia 'r 'vere studied to determine theinfluence of such environmental factors as tidal level, u.ave exposure, and theage of the individual on the time of ferti l isation. The median date of fer-ti l isation of samples taken from different environments tras obtained by back-dating early embryo stages present in the mantle cavity (Crisp, 1959b).

RESULTS OF TRANSPLANT EXPERIMENTS

TnB BnnBornc Cycr,B

Figure 1 i l lustrates the progress of ferti l isation and embryonic develop-ment in the native Ner'r 'foundland population, the transplanted populationfrom North Wales, and the original population remaining in North Wales.The median date of ferti l isation of the North Wales population, rvhether inNorth Wales (53"13'N lat) or in Conception Bay, Newfoundland (47'34'N

lat), lay between November 10 and 13, 1962, and u,as evidently influencedvery l itt le by transplantation. The median date of ferti l isation of the New-foundland population was much earlier, on about October 4, 1962. A few hadbeen ferti l ised by late September and all were ferti l ised by the middle ofOctober. By comparison, the median date of ferti l isation of B. balano'idesgrowing at mean tide level at Woods Hole, Mass. (41"32'N lat) was on ap-proximately October 22, t962. The median date at various locations in NovaScotia varied from October 9 to 20, 1962, according to tidal level and exposure(Table I), and thus was intermediate in time between Newfoundland andWoods Hole, though the two samples from Cape Breton Island, N.S., rn'ereexceptionally late in relation to their high latitude, due perhaps to exposureto higher sea temperatures caused by local outflow of warm water from theGulf of St. Lawrence during late summer or fall. It is known from studies of

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CRISP: NA & EUROPEAN BALANUS BALANOIDES , ,6?<

Frc. 1. Breedine and embrvonic develooment of Balanus bal-anoides native to\orth Walei and to Newioundland. The progressof fertilisation is shown by open circles (stage 1). Full circles andsquares represent embryonic development to the stage of earlylimb bud rudiments (stage 7), and eyed nauplii (stage l2') re-spectively. P.L. : period over which penis is shed. Upper: NorthWales population in Menai Bridge (solid lines) and after trans-plantation to Newfoundland (broken lines and crossed symbols).Lower: breeding behaviour of population indigenous to New-foundland. Ord.'ituate: percentage of population having reached the

reproductive stage indicated. Abscissa: date of observation.

this species in Europe that the date of breeding is influenced by environmentalfactors operating at this time (Crisp and Clegg, 1960) and rnay be delayedby higher temperatures (Crisp, t957, 1959a).

Teet-e I. Latitudinal variation in n-redian date of fertilisation of. Bal,anus balanoid.es in October1962 .

Place N lat Tidal levelMedian date of

fertilisation(Oct. 1962)

lo(

o

_n,,e,_.a '

/. P L

).-

o c r N O V D E C J A N - I - L t s

f,u.

-r

a '/-

l' l' 'Pl

/

a

/

Woods Hole, Mass., USAYarmouth, N.S.I-unenburg, N.S.Peggy's Cove, N.S.Herring Cove, N.S.Smith's Beach, N.S.Purcell's Cove, N.S.Parker's Cove, N.S.

Liscomb, N.S.Margaretsville, N.S.Port Hood, Cape Breton Is., N.S.Neil's Harbour, Cape Breton Is., N.S.Horse Cove, Conception Bay, Nfld.

41"32'43"49',44020144"30',44032',44"34'44"3s',44050',

45"02'.45"02',46007'46"46'+7"34',

M.T.L.-H.W.N."M.T.i..-H.W.N.H.W.M.T.L.M.T.L.H.W.t{.T.L.H.W.L.W.H.W.M.T.L.-H.W.N.H.W.H.W.\,I.T.t..-H.W.N.

22I J

t 220I J

10t9I J

209

t2I +

1.54

"M.T.L. : mean tidal level; H.W.N'. : high water neap; H.W. : high water; L.W. :low water.

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Page 4: Differences between North American and European Populations of               Balanus balanoides               Revealed by Transplantation

2636 JOURNAL FTSHERTES RESEARCH BOARD oF CANADA, voL.2s, No. 12, 1s68

From sea temperatures published by Fuglister G9a7) and correspondingair temperatures (United States Navy Department, 1955) there is in Augusta reduction of sea temperature betrveen Cap Cod and southeast Nova Scotiaf rom about 20 to about 16 C, and in November f rom about 10 to about 7 C;similarly the sea temperatures in southeast Ner'vfoundland are approximately3 degrees C lorver. Air temperatures fluctuate more widely and fall moresharply with the approaching lvinter, but shorv the same latitudinal trend.

Thus, despite minor local anomalies, earlier breeding of more northerlypopulations rvithin the latitudinal range covered is a characteristic of NorthAmerican populations just as it is of European ones. But the North Americanpopulations, when cornpared with European populations at similar latitudes,breed at least a month earlier.

Figure 1 also shows the progress of development. The Nervfoundlandpopulation, having ferti l ised a rnonth earlier, maintained their lead in de-velopment throughout the winter. The transplanted specimens developedonly slightly more slowly in Ner,vfoundland than they did at their place oforigin in North Wales. Unfortunatellr, because of the aforementioned gover-ment regulations, the experiment had to be terminated before hatching andliberation took place.

After ferti l isation, B. bolanoides undergoes a period of anecdysis ter-minated by a moult in r 'vhich the penis is lost;the testes and vesiculae seminalesatrophy at this time. Both native North American and transplanted Europeanbarnacles sho'lved similar changes, but the former were some 6 weeks in advanceof the latter. Half the native Ner,vfoundland barnacles had shed their penesbetween October 24 and November 2, 1962, whereas the corresponding datefor t lre transplanted European barnacles rvas between December 7,1962 and

January 8, 1963.

Ecc SrzB

The sizes of the eggs obtained from sarnples of 50 individuals are givenin Table II. It rvil l be seen that the size is l i tt le altered by transplantation.Barnacles from the coast of North America produce significantly larger, andthe European specimens smaller, eggs r,vhether they mature and develop inEurope or in America. The population l iving in Newfoundland, well to thenorth of Woods Hole, produce somewhat larger eggs than those of barnaclesfrom the Woods Hole district. As expected, late stage eggs rvere distinctly largerthan early stage eggs.

EFFECT OF ENVIRONMENT ON DATtr OF BREEDING

Trnar, LBvBr

Table III gives the percentage of individuals carrying eggs in samplestaken at high and lor'v levels betr'veen the tide marks in various localit ies inNova Scotia. In all cases the breeding of the high-water populations hadprogressed further, a higher percentage carrying egg masses. Breeding thusoccurs earlier higher up the shore.

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Page 5: Differences between North American and European Populations of               Balanus balanoides               Revealed by Transplantation

CRISP: NA & EUROPEAN BALANUS BALANOIDES

Tesls II. Influence of environment and origin on egg size.

2637

P]ace oforigin

Environmentduring breeding

season

Early stageeggs'

Late stageeggs'

[-ength Breadth Length Breadth

Horse Cove, Nfld.,Canada

Menai Bridge,North \&/ales,U.K,

Woods Hole,Mass., USA

I-Iorse Cove

Menai Bridge

Ilorse CoveWoods HoleMenai Bridge

u

338+7

265 +5

272+6J U / : L )

328t13

r / J f J

137 +3

143+4155+4162+6

It392+6

305+10

325+7338+6J + l t /

p

196+3

160:t4

L I L _ +

180+5t78+6

astages up to appearance of limb buds classified as early istages 1-9, Crisp, 1954); staeeswith-setae and eyes classified as late (stages 10-13). Standard eirors associated with measuremeitsare included.

Teer,n III. Effect of tidal level on breedins.

/6 of sample populationbearing egg masses at

Locality and date H.W.. L.W."

Smith's Beachnear Halifax

MargaretsvilleArgyle Sound

AdultsSpat

Parkers's Cove

Oct.196210

t220

22

J /

59

9695

100

29

339

86

"I{.W. : high water; L.W. : low water.

At Horse Cove, Newfoundland, where the tidal range was much smallerthan in Nova Scotia, a similar effect was apparent from observations madein November. Individuals growing near the high-water mark had in generalmore advanced embryos than those lower down the shore. However, in thesample collected on December 7, 1962 there lvere a few very small 1st-yearindividuals, 4-6 mm diam, carrying embryos that were much less advancedthan those of the normal sized individuals of 8 10 mm diam. This phenomenonwill be considered in the section dealing with the effect of age on breeding.

WavB ExposunB AND STTELTER

At several localit ies in Nova Scotia the breeding state of barnacles growingin exposed positions was compared with that of barnacles l iving at the sametidal level in shelter. Table IV shor,vs that ferti l isation invariably took placeearlier in sheltered situations.

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Page 6: Differences between North American and European Populations of               Balanus balanoides               Revealed by Transplantation

2638 JOURNAL FISHERIES RESEARCH BOARD OF CANADA, VOL,25 ' NO' 12 ' 1968

Taer-e IV. Effect of wave exposure and shelter on breeding.

./6 o.f sample populationbearlng egg masses wnen

Locality and date Sheltered Wave exposed

Smith's Beach nearHalifax, high water

Lunenburg, high water

Jeddore Oyster PondLiscombPort HoodPeggy's Cove

Oct.196210

12l3I J

20

52

9087875873

D

4 J

251050

AcB op Ixorvrtu.tr.s

In most localit ies the individuals that have settled in the previous spring

form a readily separable size-class. They are referred to as spat, to distinguish

them from adults in their 2nd or later year of growth. Table V gives the results

of two counts in which adults and spat were compared. In both cases the adults

ferti l ised in advance of spat.A proportion of the smallest spat present at the extreme upper l imit of

the barnacle zone, especially those living in cracks where growth is reduced,

failed to become fertilised in their first year. As mentioned above (p. 2637)'

there was evidence that a few of such individuals may mature and become fer-

ti l ised very much later than adults.

TasI-B V. Effect of age on breeding.

/6 of sample populationbearing egg masses among

Locality and date )1 year o ld (1 year o ld

AllendaleArgyle Sound

Oct.20,1962Oct.20, 1962

87 1 t l

49

DISCUSSION

Balanus balano'id'es breeds annually every autumn, and the time at which

the eggs are laid is remarkably regular (Crisp, 1959a). The date of breeding

is affected, not by the normal variations in temperature and other environmental

conditions at t l-re time, but by those some weeks earlier (Crisp and Clegg,

1960). However, if barnacles are collected in late spring or early summer and

held in a constant environment in the dark at a temperature of from 4 to

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CRISP: N.A. & EUROPEAN BITLANLIS BALANOLDES 2639

10 C, they r,vil l breed lrithin a lveek or two of the normal t inre (D. J. Crispand B. Patel, unpublished observations). It appears, therefore' that they are

sensitive to environrnental influences only for a l imited period in late summerand autumn, quite unlike species that can be induced to breed by raising thetemperature (Patel and Crisp, 1960). Therefore, the climate at other timesof year appears not to be important to the breeding cycle"

The factors that influence breeding at the relevant t ime are chiefly l ight

and temperature; experiments indicate that a regime of predominantly lol 'r 'l ight intensity at a temperature of less than 10 C for several lveeks is a nec-

essary conditioning experience (Crisp, 1957; Barnes, 1963). In the field,

breeding is advanced in places where there is greater shading, greater shelterfrom lvave exposure or water currents, and greater exposure to the air athigher tidal levels (for discussion see Crisp, 1959a) . Breeding is also advancedat higher latitudes, though there are of course variations from place to place

in response to local differences in meteorological conditions and sea temper-atures. These environmental and latitudinal factors have been shor'vn to

operate in exactly the same manner on populations on the North Americancoast and in Europe, but the American form differs from the European in theearlier onset of breeding in identical habitats, the larger size of the egg, and

the more rapid development of the embryo. These differences persist aftertransplantation in either direction, and are therefore quite independent of theenvironment during the period of gonad maturation. A further difference be-tureen the tu.o races l ies in the greater susceptibil i ty of the North Americanform to parasitism by Hemion'iscus balan'i, as is shorvn in Fig. 2, based on datafrom Crisp (1968). All these differences probably result from genetic responsesto the environment, notably to the harsher rvinters during rvhich the etnbryosdevelop, the earlier plankton blooms (see Crisp, 1964), and to the rarity of

tlre parasite Hemionisctts in the \\'estern Atlantic.

l(Ja

2o5U-o

z

9FUUL

=

Frc. 2. Infection by Hemioniscus of. Newfoundlandspecimens transplanted to Britain. Native North Walesspecimens growing in the same locality showed a low

rate of infection.

MONTHS AFTER TRANSPLANTING

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2640 JoURNAL FTsHERTES RESE-A,RCH BoARD oF CANADA, vot-. 2s, No. 12, 1968

The distribution of this species extends to much more southerly latitudeson the American coast, and its centre of abundance there is considerably furthersouth than in Europe. For this reason the comparison between the breedingof the species in Wales and in Newfoundland is the only one where the latitudeis closely comparable. The temperature of the sea during the period of mat-uration for the 6 weeks prior to ferti l isation was about the same at this latitudeon the two sides of the Atlantic, though the Newfoundland population fer-ti l ised over a month earlier. The populations further south, in Nova Scotiaand New England, though they ferti l ised somewhat later than the New-foundland population, because of the lower latitude did so at temperaturesrather higher than those prevailing in North Wales at the time of maturationand breeding (1a C dropping to 10 C) or in Nervfoundland when the nativepopulation there was maturing (13 C dropping to 9 C). Thus while the WoodsHole population were maturing, sea temperatures fell only from t7 to 12C and air temperatures lvere not much lower. These temperatures are higherthan those hitherto quoted (10 C) for conditioning the species in Europe (Crisp,1957; Barnes, 1963) and suggest that in America, over the southern part ofits range at least, B. balano,ides is probably adapted to mature at higher tem-peratures than it does in Europe. Probably the rate of fall in temperature,the change in day length, and other factors as well as the actual temperaturelevel may combine in determining'ivhen maturation and breeding take place.The two races clearly react differently and breed at different times rvhen tl-reenvironmental conditions are identical.

ACKNOWLEDGMENTS

I am greatly indebted to \t l iss Elizabeth Brown for assistance in collectingtransplanted specirnens from Newfoundland, and to Mr P. S. \lleadon's forcollecting samples of. Balanus balanoid,es from Nlenai Bridge and dispatchingthem by air. The Nuffleld Foundation, Memorial University of St. John's,Nfld., and Dalhousie University, Halifax, N.S., supported me while I tasengaged in this research. I wish to thank \{r H. R. Found and Mr H. Bradley,Department of Fisheries of Canada, for their help in arranging for a veterinaryinspection of the barnacles at the port of immigration and in obtaining specialsanction from the Canadian Government for the temporary introduction ofexotic f ish.

REFERENCES

Benxns, H. 1958. Regarding the southern limits of Balanus bol'anoiiles L. Oikos, 9: 139-157.1963. Light, temperature and the breeding of Bal'anus bal.anoid.es. J. Marine Biol,

Assoc. U.K., 43: 717-725.

Cnrsr, D. J. 1954. The breeding of Balanus porcatus (da Costa) in the Irish Sea. Ibid.,33:473496.

1957. Effect of low temperature on the breeding of marine animals. Nature, London,1 7 9 : 1 1 3 8 - 1 1 3 9 .

1959a. Factors influencing the time of breeding of. Balanus bal.onoides. Oikos, l027 5-289.

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CRISP: NA & EUROPEAN BALANUS BALANOIDES 264L

1959b. The rate of development of. Balanus bal,anoid.es (L.) embryos in aitro. J, AnimalEcol.. 28: Ll9-132.

1964. Racial differences between North American and European forms of Balanusbalanoid,es. J. Marine Biol. Assoc. U.K., 44: 33-45.

1968. Distribution of the parasitic isopod Hemioniscus balani with special reference tothe east coast of North America. J. Fish. Res. Bd. Canada,25(6): 1161-1167.

Cnrsr, D. J., eno D. J. Clncc. 1960. The induction of the breeding condition in Bal,anusbal'anodd.es (L.). Oikos, 11: 265-275.

Fucr-rsren, F. C. 1947. Average monthly sea surface temperatures of the western NorthAtlantic Ocean. Papers Phys. Oceanog. Meteorol., 10(2): 25 p.

Pernl, B., eNo D. J. Cnrsr. 1960. The influence of temperature on the breeding and moultingof some warm-water species of operculate barnacles. J. Marine Biol. Assoc. U.K.,39:667-680.

Uxrrno S:rerps Nevy DBpatntpNr. 1955, Marine climatic atlas of the world. Vol. 1. NorthAtlantic Ocean. NAVAER 50-1C-528, Washington, D.C.275 p.

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