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Elminius modestus Darwin: Further European records
ELMINIUS MODESTUS FURTHER EUROPEAN H. BARNES a n d
DARWIN: RECORDS*
MARGARET BARNES
The Marine Station, Millport, Scotland
PROFESSOR HANS PETTERSSON'S work was above all concerned with the deep oceans; it seems necessary, therefore, to give some explanation for the inclusion in a volume such as this of a contribution dealing with intertidal ecology. The reasons can be simply stated: first, a wish to honour Hans Pettersson who, although primarily concerned with the oceans, has never been a narrow-minded specialist but who. on the contrary, has always been interested in every aspect of marine science. These grounds would be sufficient in themselves, but there is a second reason; we wish to acknowledge the hospitality he has afforded at GOteborg, and the kindness he has shown on many occasions. Elmhlius modestus Darwin is an Australasian barnacle which has become established (during World War II) in Europe; from the original points of introduction it has spread widely and in suitable places may now be found from northern G e r m a n y to Portugal (for references to the literature see, BARNES and BARNES, 1960, 1961: Ki.JHL, 1963; FISCHER-PIETTE and FOREST, 1961. which includes most of the publications dealing with southern Europe). The spread of this immigrant has been followed in some detail and is perhaps the best documented example of the invasion of a marine animal into a new area; the fact that it is a sedentary and intertidal species makes this particularly easy. We have recently had the opportunity to examine much of the southern and south-western coasts of Europe, including France, Spain and Portugal and record here some further data on the occurrence, spread and general ecology of E. modestus on these coasts. An account will first be given of the present observations and they will then be discussed in relation to the present distribution. Frallee Brittany, North Coast Gram'i/le (Cherbourg peninsula): absent on the open coast. St. Quay Portrieux: harbour wall has dense Chthamahls stellatus and Balanus balanoides * This work was carried out under the ONR contract NR 104-745 and gratitude is expressed to the Office of Naval Research (U.S.A.) for its support.
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BARNES, H. AND BARNES, MARGARET
a n d a m o n g s t the heavy cover EIminitts is c o m m o n but scattered: n o n e with e g g - m a s s e s (June). Port Blanc: a l t h o u g h on the open n o r t h coast, the bay is largely protected b v m a n y offshore islands; s a n d y beach h a d boulders a n d rock reef; Elminius c o m m o n on b o t h ; e g g - m a s s e s were present in early June. Ldzardrieux: this is s o m e 10 k m up the n a r r o w Trieux e~tuary. EIminhts c o m m o n on the road bridge; situation extremely m u d d y ; p r o b a b l y m u c h reduced salinity. TrOquier: very similar to previous station, high up the J a u d y estuary; very m u d d y ; Elminius very c o m m o n on stones in m u d even at high levels; a b u n d a n t on walls reaching across the shore. Perros-Guirec: Elminius a b u n d a n t on h a r b o u r wall; m o r e on inside; very m a n y large a n i m a l s , partly corroded, p r o b a b l y several years old. Ploamanac'h: typical open coast; Elmh~ius absent. Pointe de Portusval: s a n d y beach with large boulders: Elminius occasional at higher levels a n d c o m m o n at lower levels particularly in m o r e sheltered places; the station is relatively exposed. Tr#mazon: Elminius a b s e n t on exposed open coast but c o m m o n in sheltered bay; a n i m a l s up to 10 m m diameter on boulders on s a n d y beach. Brittato', Loire, and west coast Pornic: inner h a r b o u r a b u n d a n t Elminius; on stones a n d walls leading to h a r b o u r m o u t h , c o m m o n ; present on m u s s e l s a n d u n d e r dense weed: outside the h a r b o u r is a rocky s h o r e with a reef r u n n i n g o u t to sea. In June spat was a b u n d a n t in bare places towards the sea, but relatively few at mid- a n d higher levels. Adults were c o m m o n . W h e n visited later, in September, the Elminius p o p u l a t i o n had increased on the lower s h o r e a n d at mid-tide levels. La Bernerie en Retz: only seen near high tide; Elminius not found. Les Moutiers: s a n d y beach with w o o d e n breakwaters; Elminius up to 10 m m present on the larger stones on the beach. Only seen at a relatively high tide; probably m o r e c o m m o n . Croix de Vie: o u t e r rocky coast, Elminius a b s e n t ; a b u n d a n t , however, on the outer estuary wall a n d on stones u n d e r dense weed; present on the mussels. A b u n d a n t on inner hatb o u t wall: situation in h a r b o u r a n d estuary very m u d d y . Les Sables d'Olonne: s a n d y s h o r e flanked on one side by retaining wall of the h a r b o u r : Elminius occasional on wall. L'Aiguillon sur Mer: absent. La Rochelle, Arcachon, Ciboure, Hendaye: absent t h r o u g h o u t , a l t h o u g h very careful search was m a d e in such p l a c e s - - m u d d y h a r b o u r s and e s t u a r i e s - - w h i c h are particularly favourable to Elminius.
Spain North coast Elminius was n o t f o u n d at the following places: Pasajes de San J u a n , Orio, Z a r a u z , Laredo, Santofia, N e u v a Berria, Comillas, Ribadesella. Villaviciosa: the inner part of the Ria de Villaviciosa consists of extensive m u d flats; a n d at the s e a w a r d end a n a r r o w c h a n n e l with "'retaining" walls leads out to the sea: Elm#tius was present in small n u m b e r s , usually not near e n o u g h to breed, on the s t o n e s : n o n e greater t h a n 8 m m a n d all m a y be c u r r e n t year's spat. Gijdn: EIminius was occasional on the stones on the beach a n d on the rocks at the left (true) side o f the Playa de San Lorenzo. It was t h o u g h t that this population m i g h t have its origin in the new Puerto del M u s e l ; careful search was m a d e in parts of the latter, c o m mercial a n d fishing sections, but Elminius was never found. T h e shore is heavily covered with m u d . Luarca: Elminius was n o t f o u n d either on the shore or in the h a r b o u r .
E h n i n i u s m o d e s t u s DARWIN: FURTHER EUROPEAN RECORDS
25
Navia: shore by road bridge over the Ria: no barnacles: probably too fresh water at this point: much mud.
Ribadeo: Elrninius was very abundant in a small bay off the Ria; animals up to 15 m m diameter, 10 per cent of population with egg-masses.
Foz: Elminius abundant on stcnes set in muddy sand and on inner and outer sides of the harbour wall.
Vivero: Elminius a b u n d a n t on harbour wall, high up Ria. Ortigueria: a large Ria, Ria de Santa Maria; Elminius abundant on stones and walls offish harbour: all sizes including "old" corroded animals. On the wall a dense band of Elminius lies below Chthamalus stellatus and is in direct competition "'vertically" with the latter. Cedeira: well inside the Ria: similar to previous situation: Elminitts a b u n d a n t forming a well-marked band below the Chtharnalus stellatus. Fene: Ria de El Ferrol; wall by jetty for El Ferrol ferry; situation as in previous station with dense band of Elminius below Chthamahts stellatus. Puentedeume: Ria de Ares o Betanzos: this is a very large and wide Ria. Elminius extremely a b u n d a n t with only scattered Chthamahts stellatus above it on the wall of the harbour. Impression gained that Chthamalus is now being restricted at its lower level by Elminius. Sada: this is on the opposite side of the same Ria: situation similar to previous with Elminius a b u n d a n t on walls.
Serantes: pebbly beach; Elrnhlius not found but only seen near high tide. Serantes harbour: also seen only near high tide; this is on the side of the R.ia de la Corufia; only scattered Elminius: water here was clear. Possibly more would be found at lower levels.
Portosin: Ria de Muros y Noya: Portosin is some way towards the entrance to the Ria; water clear; sandy beach with rocky promontory; Elminius was c o m m o n but not abundant: tends to occur in any bare places amongst the relatively dense Chthamalus stellatus, amongst the Balantts balanoides, and on mussels. Son: near the entrance to same Ria: small scattered ElmhTius at lower levels only; exposure much greater at this point.
Punta del Castro: essentially open coast; Elminhts absent. Ponteve~h'a (Mar#t): there is a large harbour wall and a "back-wash" behind; Elmhffus is c o m m o n on the Ria side of the wall: in the back-wash it completely dominates all solid substrata, where there are only scattered Chthamahts: situation is extremely quiet and shore very muddy. Bueu: moderate exposure; Elminitts occasional at lower levels on stones and mussels on a rock reef running across beach. Arcada: Elminius a b u n d a n t on rocks in mud, Teis: wall alongside of Ria; Elmhthts common. Bayona: well down Ria, subsidiary bay: Elmhth~s c o m m o n in harbour. Cabo Silleh'o." very exposed: Elminius absent,
Portttgal Camhrha: wall of fish harbour still under construction: Elminhts a b u n d a n t forming a distinct band under the Chthamahts stellatus: water muddy and probably freshened. Viana-do-Castelo: Elmmius c o m m o n but not abundant on fish-harbour walls and slips; water muddy and much green weed.
Aveiro (Gafanha do Nazard): ship's channels with landing stages; very m u d d y ; dense Elminius in metre-wide band; animals up to 15 m m diameter; particularly well developed in shade where weed cover less.
Barra: Entrance to the lagoon; just inside is more exposed than expected, and shore similar to more exposed places. Only single Elrninius found on a mussel.
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BARNES, H. AND BARNES, MARGARET
Costa Nova do Prado: this is inside the lagoon : Elmhtius a b u n d a n t on landing stage of ferry
boats. Only artificial structures are available for settlement; shore is extensive sandy beaches. Figueira da Foz: Elrnhlhts abundant on slip at entrance to harbour; lying below the Chthamahls. Gala: on a branch of the estuary of the Mondego; sandy-muddy beach; EImhthts abundant
on inner side of harbour wall. S~o Martinho do Porto: narrow entrance to small bay; Elminius common on harbour wall;
up to 10 mm and much spat in bare places; water muddy. Elminius was not found further south in Portugal; Peniche, Ericeira Bay, Ericeira Point, Lisbon, Cabo de Espichel, Sagres, Villa Real de Santo Ant6nio, or Puerto de Santa Maria (Spain) ; a particularly careful search was made in the most likely places, for example, Lisbon. N o r was it found on the southern coasts of Spain and France.
DISCUSSION The distribution of Elminius modestus along the coasts of France in 1955 has been summarized and discussed by BIsHoP and CRISP (1958, for further references). At that time they recognized four sectors: the first, from Belgium to Cap de la Hague, where Elminius was present in quantity on all suitable shores; a second, from Cap de ]a Hague down the western side of the Cherbourg peninsula and as far west as the estuary of the Tri6ux where it was absent; a third from the estuary of the Jaudy to Brest where it was common in all the major estuaries and ports; and a fourth, on the west coast, south from the Rade de Brest where it was rare with only isolated specimens as far south as Lorient (a single animal was found at St. Jean de Luz). They considered that the population in the eastern part of the Channel and that in Brittany were separately established, the former probably from Brest and the latter from the Le Havre-Seine district, which itself was initially quite distinct from the immigration into Belgium. They belie,~ed that, although conditions in the G u l f of St. Malo would, in places, be quite favourable to Elminius once established, immigration is hindered by the very large tidal range which reduces the containment factor of any suitable estuaries. The new records for 1963 (Fig. l) suggest that there has been some spread and further consolidation of the species along the northern coast of France. Little change is indicated along the western side of the Cherbourg peninsula since it is still absent at Granville. There has, however, been an extension south-westwards from the Jaudy estuary (Tr6quier). The abundance at L~zardrieux contrasts sharply with the previous absence; the situation, in the Tri6ux estuary is particularly favourable being similar to that at Tr6quier on the Jaudy where Elminius was abundant even in 1954. It is now common in many places b~tween L~zardrieux and St. Quay Portrieux. On the west coast of France BISHOP, CRISP, FISCHER-PIETTEand PRENANT
Ehninius modestus DARWIN: FURTHER EUROPEAN RECORDS
27
(1957) found the species abundant in the Rade de Brest, and an increase at Concarneau and in the Lorient area was noted by 1957 (CRtsP, 1959, w h o found it as far south as Etel). FISCHER-PtETTE and FOREST ( 1 9 6 1 ) r e p o r t Elminius as abundant in the Golfe de Morbihan by 1960 and as far south as St. Br6vin-l'Ocean (on the south side o f the Loire estuary); this represents an advance of 95 k m between 1957 and 1960. Between 1960 and 1963 there
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t FIG. 1. The distribution ofElminius modesttts in south-west Europe: data from all available sources (see text); dates show when observations were made. © Statiohs examined in survey carried out in 1963.
28
BARNES, H. AND BARNES, MARGARET
has been a further southward extension at about the same rate. E/m/n/us is now c o m m o n at Pornic both in the harbour and on the nearby coast, as well as at Croix de Vie. The presence at Les Sables d'OIonne indicates an extension southwards of some 100 km from St. BrOvin-l'Ocean during the last three years. The presence of the immigrant E. modestus in Spain was first recorded by FISCHER-PIETTE and PRENANT (1956) who in 1955 found it at a number of localities in the north-west between Noya and Jubia in Galicia. It was common in the Ria el Ferrol and the Ria de Betanzos. They considered the southern limit to be at Noya. FISCHER-PIETTE and FOREST (1961) record a further advance along the north coast by 1958: at Cedeira it was localized on the rocks of the promenade, while at E1 Barquero it was present throughout the estuary. The most easterly points reached were Aviles and San Juan de Nieva near the entrance to the Ria de Avil6s. In 1955 Fischer-Pierre and Prenant failed to find Elminius in the Ria de Vigo or the Ria de Pontevedra. A visit to Portugal in 1956 (FISCHER-PIETTE and PRENANT, 1957) showed that it was present at Viano do Castelo (widely spaced individuals) very abundant at Leixoes, present at Foz de Duro and Aveiro and at the approaches to Gafanha but absent at the Barra de Aveiro. Since the Ria de Vigo and Ria de Pontevedra were carefully searched in 1955 the inference may be drawn that the immigration to Portugal was a separate "infection". By the winter of 1957-1958 (FISCHER-PIETTE and FOREST, 1961 ) the abundance and dominance had increased at all the Portuguese stations re-investigated and there was a further southward extension to Figueira da Foz and Silo Martinho do Porto: between 1955 and 1957 (winter) the advance was about 140 kin. The present survey shows that Elminius has consolidated its position along the north coast of Spain. At Cedeira it is now abundant and forms a welldefined band successfully eliminating Chthamalus stellatus at lower levels. Ortigueira, Vivero, and Ribadeo (all abundant) are all new records. The eastward expansion is, however, slight with only small populations at Gij6n and Villaviciosa--an extension of only 50 km. Gij6n is, however, separated from Avil6s by the very exposed Cabo Penas. The gap between Noya and Vianodo-Castelo has been bridged since Elminius is now present at Portosin and Son, abundant in the Ria de Pontevedra (Matin. Bueu) in the Ria de Vigo (Teis, Bayona), and at Caminha (Portugal). FISCHER-PIETTE and FOREST (1961) were unable to explain the absence in the Ria de Vigo where conditions both for its introduction and consolidation are very favourable: Elmmius has now successfully entered the estuary but the reason for any delay is still obscure. There has been no extension south o f S a o Martinho de Porto since its first discovery there in the winter of 1957-58. The observations in reference to previous data may be summarized thus: (i) There has been consolidation and a slight extension of the population of north Brittany into the G u l f of St. Malo.
Elmhtius modestus
DARWIN: FURTHER EUROPEAN RECORDS
29
(ii) There has been an extension southwards on the Atlantic coast of France amounting to 100 km with the advancing front now at Les Sables d'Olonne. (iii) There has been consolidation but only a slight extension along the northern coast of Spain. (iv) There has been much consolidation of the populations along the western Spanish coast and that of Portugal, but no further extension southwards: the southern limit is still at S~o Martinho do Porto. When it is remembered that the small advance eastwards on the French coast from the Jaudy estuary to St. Quay Portrieux (less than 50 km) has taken place over some nine years the marked retardation to spread (considered to be due to the large tidal range) in the Gulf of St. Malo is emphasized. Vectors may ultimately carry the species to the ports so that the Cherbourg-Brittany hiatus is bridged but it must also be stressed that the exposed coast between many of the estuaries will tend to hinder spread by marginal distribution. The extension on the western coast of France is much greater and has taken place at a far greater rate--from St. Brevin-l'Ocean to Les Sables d'Olonne (100 km) in three years; this might have been expected with the increasing population density to the north and the presence of small harbours with much fishing activity along this coast. Progress south from Los Sables d'Olonne may be slow: there are large stretches of sand. It is perhaps surprising that it" has not reached La Rochelle where it would find conditions favourable. Further south the long sandy C6te des Landes will provide a very pronounced bar to marginal dispersion but if it became established in the Basin d'Arcachon one would expect it--like Balanus improt, isus--to flourish ; nevertheless, southwards the long sandy coast from there to near the Spanish border will again retard the spread. Consolidation in the bays and estuaries of north-west Spain would have most certainly been expected. Eastward expansion on the north coast is retarded by the physical character of the shore. Beyond Villaviciosa the exposed coast has steep cliffs and jutting headlands with few semi-enclosed estuaries or large harbours. There has been no expansion southwards from S~.o Martinho do Porto for several years. Here again the long sandy coast and the exposed Peniche peninsula may prove an insuperable barrier to marginal dispersion. If carried by vector to Lisbon ElmhTius would be expected to flourish in the Tagus estuary. SUMMARY An account is given of some observations on Elminius modestus Darwin along the coasts of south and south-west Europe including northern France, Spain and Portugal. The consolidation and extension of the immigrant are discussed.
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BARNES~ H. AND BARNES, MARGARET REFERENCES
BARNES, H. and BARNES, M. (1960) Recent spread and present distribution of the barnacle Elminhts modestus Darwin in north-west Europe. Proc. zool. Soc., Lond. 135, 137-145. BARNES, H. and BARNES, M. (1961) Recent spread and present distribution of the barnacle Elminius modestus Darwin in south-west Scotland. Glasg. Nat. 18, 121-129. BisHoP, M. W. H. and CRISP, D. J. (1958) The distribution of the barnacle Elminius modestus Darwin in France. Proc. zool. Soc. Lond., 131, 109-134. BISHOP, M. W. H., CRISP, D. J., FISCHER-PET'rE, E. and PRENANT, M. (1957) Sor l'ecologie des cirripedes de la c6te atlamique frangaise. Bull. lnst. Oceanogr. Monaco, No. 1099, 12 pp. CRISP, D. J. (1959) A further extension of Elminius modestus Darwin on the west coast of France. Beaufortia, 7 (82), 37-39. FISCHER-PmTTE, E. and FOREST, J. (1961) Nouveaux progres du cirrip/~de austral Elmhzhts modestus Darwin sur les c6tes atlantiques fran~;aise et ib6riques. Crustaceana, 2, 293299. FISCrtER-PIEX'rE, E. and PRENANT, M. (1956) Distribution des Cirripedes intercotideaux d'Espagne septentrionale. Bull. Centre fit. Rech. sc. Biarritz, 1, 7-19. FISCHER-PIETTE,E. and PRENANT,M. (1957) Quelques donnees ecologiques sur les Cirripedes intercotidaux de Portugal, de l'Espagne du sud et du Nord du Maroc. Bull. Centre F_.t. Rech. sc. Biarrit z, 3, 361-368. KUHL, H. (1963) Die Verbreitung yon Elminius modestus (Cirripedia Thoracica) an der deutschen Kiiste. Crustaceana, 5, 99-111.
DARWIN: RECORDS*
MARGARET BARNES
The Marine Station, Millport, Scotland
PROFESSOR HANS PETTERSSON'S work was above all concerned with the deep oceans; it seems necessary, therefore, to give some explanation for the inclusion in a volume such as this of a contribution dealing with intertidal ecology. The reasons can be simply stated: first, a wish to honour Hans Pettersson who, although primarily concerned with the oceans, has never been a narrow-minded specialist but who. on the contrary, has always been interested in every aspect of marine science. These grounds would be sufficient in themselves, but there is a second reason; we wish to acknowledge the hospitality he has afforded at GOteborg, and the kindness he has shown on many occasions. Elmhlius modestus Darwin is an Australasian barnacle which has become established (during World War II) in Europe; from the original points of introduction it has spread widely and in suitable places may now be found from northern G e r m a n y to Portugal (for references to the literature see, BARNES and BARNES, 1960, 1961: Ki.JHL, 1963; FISCHER-PIETTE and FOREST, 1961. which includes most of the publications dealing with southern Europe). The spread of this immigrant has been followed in some detail and is perhaps the best documented example of the invasion of a marine animal into a new area; the fact that it is a sedentary and intertidal species makes this particularly easy. We have recently had the opportunity to examine much of the southern and south-western coasts of Europe, including France, Spain and Portugal and record here some further data on the occurrence, spread and general ecology of E. modestus on these coasts. An account will first be given of the present observations and they will then be discussed in relation to the present distribution. Frallee Brittany, North Coast Gram'i/le (Cherbourg peninsula): absent on the open coast. St. Quay Portrieux: harbour wall has dense Chthamahls stellatus and Balanus balanoides * This work was carried out under the ONR contract NR 104-745 and gratitude is expressed to the Office of Naval Research (U.S.A.) for its support.
23
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BARNES, H. AND BARNES, MARGARET
a n d a m o n g s t the heavy cover EIminitts is c o m m o n but scattered: n o n e with e g g - m a s s e s (June). Port Blanc: a l t h o u g h on the open n o r t h coast, the bay is largely protected b v m a n y offshore islands; s a n d y beach h a d boulders a n d rock reef; Elminius c o m m o n on b o t h ; e g g - m a s s e s were present in early June. Ldzardrieux: this is s o m e 10 k m up the n a r r o w Trieux e~tuary. EIminhts c o m m o n on the road bridge; situation extremely m u d d y ; p r o b a b l y m u c h reduced salinity. TrOquier: very similar to previous station, high up the J a u d y estuary; very m u d d y ; Elminius very c o m m o n on stones in m u d even at high levels; a b u n d a n t on walls reaching across the shore. Perros-Guirec: Elminius a b u n d a n t on h a r b o u r wall; m o r e on inside; very m a n y large a n i m a l s , partly corroded, p r o b a b l y several years old. Ploamanac'h: typical open coast; Elmh~ius absent. Pointe de Portusval: s a n d y beach with large boulders: Elminius occasional at higher levels a n d c o m m o n at lower levels particularly in m o r e sheltered places; the station is relatively exposed. Tr#mazon: Elminius a b s e n t on exposed open coast but c o m m o n in sheltered bay; a n i m a l s up to 10 m m diameter on boulders on s a n d y beach. Brittato', Loire, and west coast Pornic: inner h a r b o u r a b u n d a n t Elminius; on stones a n d walls leading to h a r b o u r m o u t h , c o m m o n ; present on m u s s e l s a n d u n d e r dense weed: outside the h a r b o u r is a rocky s h o r e with a reef r u n n i n g o u t to sea. In June spat was a b u n d a n t in bare places towards the sea, but relatively few at mid- a n d higher levels. Adults were c o m m o n . W h e n visited later, in September, the Elminius p o p u l a t i o n had increased on the lower s h o r e a n d at mid-tide levels. La Bernerie en Retz: only seen near high tide; Elminius not found. Les Moutiers: s a n d y beach with w o o d e n breakwaters; Elminius up to 10 m m present on the larger stones on the beach. Only seen at a relatively high tide; probably m o r e c o m m o n . Croix de Vie: o u t e r rocky coast, Elminius a b s e n t ; a b u n d a n t , however, on the outer estuary wall a n d on stones u n d e r dense weed; present on the mussels. A b u n d a n t on inner hatb o u t wall: situation in h a r b o u r a n d estuary very m u d d y . Les Sables d'Olonne: s a n d y s h o r e flanked on one side by retaining wall of the h a r b o u r : Elminius occasional on wall. L'Aiguillon sur Mer: absent. La Rochelle, Arcachon, Ciboure, Hendaye: absent t h r o u g h o u t , a l t h o u g h very careful search was m a d e in such p l a c e s - - m u d d y h a r b o u r s and e s t u a r i e s - - w h i c h are particularly favourable to Elminius.
Spain North coast Elminius was n o t f o u n d at the following places: Pasajes de San J u a n , Orio, Z a r a u z , Laredo, Santofia, N e u v a Berria, Comillas, Ribadesella. Villaviciosa: the inner part of the Ria de Villaviciosa consists of extensive m u d flats; a n d at the s e a w a r d end a n a r r o w c h a n n e l with "'retaining" walls leads out to the sea: Elm#tius was present in small n u m b e r s , usually not near e n o u g h to breed, on the s t o n e s : n o n e greater t h a n 8 m m a n d all m a y be c u r r e n t year's spat. Gijdn: EIminius was occasional on the stones on the beach a n d on the rocks at the left (true) side o f the Playa de San Lorenzo. It was t h o u g h t that this population m i g h t have its origin in the new Puerto del M u s e l ; careful search was m a d e in parts of the latter, c o m mercial a n d fishing sections, but Elminius was never found. T h e shore is heavily covered with m u d . Luarca: Elminius was n o t f o u n d either on the shore or in the h a r b o u r .
E h n i n i u s m o d e s t u s DARWIN: FURTHER EUROPEAN RECORDS
25
Navia: shore by road bridge over the Ria: no barnacles: probably too fresh water at this point: much mud.
Ribadeo: Elrninius was very abundant in a small bay off the Ria; animals up to 15 m m diameter, 10 per cent of population with egg-masses.
Foz: Elminius abundant on stcnes set in muddy sand and on inner and outer sides of the harbour wall.
Vivero: Elminius a b u n d a n t on harbour wall, high up Ria. Ortigueria: a large Ria, Ria de Santa Maria; Elminius abundant on stones and walls offish harbour: all sizes including "old" corroded animals. On the wall a dense band of Elminius lies below Chthamalus stellatus and is in direct competition "'vertically" with the latter. Cedeira: well inside the Ria: similar to previous situation: Elminitts a b u n d a n t forming a well-marked band below the Chtharnalus stellatus. Fene: Ria de El Ferrol; wall by jetty for El Ferrol ferry; situation as in previous station with dense band of Elminius below Chthamahts stellatus. Puentedeume: Ria de Ares o Betanzos: this is a very large and wide Ria. Elminius extremely a b u n d a n t with only scattered Chthamahts stellatus above it on the wall of the harbour. Impression gained that Chthamalus is now being restricted at its lower level by Elminius. Sada: this is on the opposite side of the same Ria: situation similar to previous with Elminius a b u n d a n t on walls.
Serantes: pebbly beach; Elrnhlius not found but only seen near high tide. Serantes harbour: also seen only near high tide; this is on the side of the R.ia de la Corufia; only scattered Elminius: water here was clear. Possibly more would be found at lower levels.
Portosin: Ria de Muros y Noya: Portosin is some way towards the entrance to the Ria; water clear; sandy beach with rocky promontory; Elminius was c o m m o n but not abundant: tends to occur in any bare places amongst the relatively dense Chthamalus stellatus, amongst the Balantts balanoides, and on mussels. Son: near the entrance to same Ria: small scattered ElmhTius at lower levels only; exposure much greater at this point.
Punta del Castro: essentially open coast; Elminhts absent. Ponteve~h'a (Mar#t): there is a large harbour wall and a "back-wash" behind; Elmhffus is c o m m o n on the Ria side of the wall: in the back-wash it completely dominates all solid substrata, where there are only scattered Chthamahts: situation is extremely quiet and shore very muddy. Bueu: moderate exposure; Elminitts occasional at lower levels on stones and mussels on a rock reef running across beach. Arcada: Elminius a b u n d a n t on rocks in mud, Teis: wall alongside of Ria; Elmhthts common. Bayona: well down Ria, subsidiary bay: Elmhth~s c o m m o n in harbour. Cabo Silleh'o." very exposed: Elminius absent,
Portttgal Camhrha: wall of fish harbour still under construction: Elminhts a b u n d a n t forming a distinct band under the Chthamahts stellatus: water muddy and probably freshened. Viana-do-Castelo: Elmmius c o m m o n but not abundant on fish-harbour walls and slips; water muddy and much green weed.
Aveiro (Gafanha do Nazard): ship's channels with landing stages; very m u d d y ; dense Elminius in metre-wide band; animals up to 15 m m diameter; particularly well developed in shade where weed cover less.
Barra: Entrance to the lagoon; just inside is more exposed than expected, and shore similar to more exposed places. Only single Elrninius found on a mussel.
26
BARNES, H. AND BARNES, MARGARET
Costa Nova do Prado: this is inside the lagoon : Elmhtius a b u n d a n t on landing stage of ferry
boats. Only artificial structures are available for settlement; shore is extensive sandy beaches. Figueira da Foz: Elrnhlhts abundant on slip at entrance to harbour; lying below the Chthamahls. Gala: on a branch of the estuary of the Mondego; sandy-muddy beach; EImhthts abundant
on inner side of harbour wall. S~o Martinho do Porto: narrow entrance to small bay; Elminius common on harbour wall;
up to 10 mm and much spat in bare places; water muddy. Elminius was not found further south in Portugal; Peniche, Ericeira Bay, Ericeira Point, Lisbon, Cabo de Espichel, Sagres, Villa Real de Santo Ant6nio, or Puerto de Santa Maria (Spain) ; a particularly careful search was made in the most likely places, for example, Lisbon. N o r was it found on the southern coasts of Spain and France.
DISCUSSION The distribution of Elminius modestus along the coasts of France in 1955 has been summarized and discussed by BIsHoP and CRISP (1958, for further references). At that time they recognized four sectors: the first, from Belgium to Cap de la Hague, where Elminius was present in quantity on all suitable shores; a second, from Cap de ]a Hague down the western side of the Cherbourg peninsula and as far west as the estuary of the Tri6ux where it was absent; a third from the estuary of the Jaudy to Brest where it was common in all the major estuaries and ports; and a fourth, on the west coast, south from the Rade de Brest where it was rare with only isolated specimens as far south as Lorient (a single animal was found at St. Jean de Luz). They considered that the population in the eastern part of the Channel and that in Brittany were separately established, the former probably from Brest and the latter from the Le Havre-Seine district, which itself was initially quite distinct from the immigration into Belgium. They belie,~ed that, although conditions in the G u l f of St. Malo would, in places, be quite favourable to Elminius once established, immigration is hindered by the very large tidal range which reduces the containment factor of any suitable estuaries. The new records for 1963 (Fig. l) suggest that there has been some spread and further consolidation of the species along the northern coast of France. Little change is indicated along the western side of the Cherbourg peninsula since it is still absent at Granville. There has, however, been an extension south-westwards from the Jaudy estuary (Tr6quier). The abundance at L~zardrieux contrasts sharply with the previous absence; the situation, in the Tri6ux estuary is particularly favourable being similar to that at Tr6quier on the Jaudy where Elminius was abundant even in 1954. It is now common in many places b~tween L~zardrieux and St. Quay Portrieux. On the west coast of France BISHOP, CRISP, FISCHER-PIETTEand PRENANT
Ehninius modestus DARWIN: FURTHER EUROPEAN RECORDS
27
(1957) found the species abundant in the Rade de Brest, and an increase at Concarneau and in the Lorient area was noted by 1957 (CRtsP, 1959, w h o found it as far south as Etel). FISCHER-PtETTE and FOREST ( 1 9 6 1 ) r e p o r t Elminius as abundant in the Golfe de Morbihan by 1960 and as far south as St. Br6vin-l'Ocean (on the south side o f the Loire estuary); this represents an advance of 95 k m between 1957 and 1960. Between 1960 and 1963 there
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t FIG. 1. The distribution ofElminius modesttts in south-west Europe: data from all available sources (see text); dates show when observations were made. © Statiohs examined in survey carried out in 1963.
28
BARNES, H. AND BARNES, MARGARET
has been a further southward extension at about the same rate. E/m/n/us is now c o m m o n at Pornic both in the harbour and on the nearby coast, as well as at Croix de Vie. The presence at Les Sables d'OIonne indicates an extension southwards of some 100 km from St. BrOvin-l'Ocean during the last three years. The presence of the immigrant E. modestus in Spain was first recorded by FISCHER-PIETTE and PRENANT (1956) who in 1955 found it at a number of localities in the north-west between Noya and Jubia in Galicia. It was common in the Ria el Ferrol and the Ria de Betanzos. They considered the southern limit to be at Noya. FISCHER-PIETTE and FOREST (1961) record a further advance along the north coast by 1958: at Cedeira it was localized on the rocks of the promenade, while at E1 Barquero it was present throughout the estuary. The most easterly points reached were Aviles and San Juan de Nieva near the entrance to the Ria de Avil6s. In 1955 Fischer-Pierre and Prenant failed to find Elminius in the Ria de Vigo or the Ria de Pontevedra. A visit to Portugal in 1956 (FISCHER-PIETTE and PRENANT, 1957) showed that it was present at Viano do Castelo (widely spaced individuals) very abundant at Leixoes, present at Foz de Duro and Aveiro and at the approaches to Gafanha but absent at the Barra de Aveiro. Since the Ria de Vigo and Ria de Pontevedra were carefully searched in 1955 the inference may be drawn that the immigration to Portugal was a separate "infection". By the winter of 1957-1958 (FISCHER-PIETTE and FOREST, 1961 ) the abundance and dominance had increased at all the Portuguese stations re-investigated and there was a further southward extension to Figueira da Foz and Silo Martinho do Porto: between 1955 and 1957 (winter) the advance was about 140 kin. The present survey shows that Elminius has consolidated its position along the north coast of Spain. At Cedeira it is now abundant and forms a welldefined band successfully eliminating Chthamalus stellatus at lower levels. Ortigueira, Vivero, and Ribadeo (all abundant) are all new records. The eastward expansion is, however, slight with only small populations at Gij6n and Villaviciosa--an extension of only 50 km. Gij6n is, however, separated from Avil6s by the very exposed Cabo Penas. The gap between Noya and Vianodo-Castelo has been bridged since Elminius is now present at Portosin and Son, abundant in the Ria de Pontevedra (Matin. Bueu) in the Ria de Vigo (Teis, Bayona), and at Caminha (Portugal). FISCHER-PIETTE and FOREST (1961) were unable to explain the absence in the Ria de Vigo where conditions both for its introduction and consolidation are very favourable: Elmmius has now successfully entered the estuary but the reason for any delay is still obscure. There has been no extension south o f S a o Martinho de Porto since its first discovery there in the winter of 1957-58. The observations in reference to previous data may be summarized thus: (i) There has been consolidation and a slight extension of the population of north Brittany into the G u l f of St. Malo.
Elmhtius modestus
DARWIN: FURTHER EUROPEAN RECORDS
29
(ii) There has been an extension southwards on the Atlantic coast of France amounting to 100 km with the advancing front now at Les Sables d'Olonne. (iii) There has been consolidation but only a slight extension along the northern coast of Spain. (iv) There has been much consolidation of the populations along the western Spanish coast and that of Portugal, but no further extension southwards: the southern limit is still at S~o Martinho do Porto. When it is remembered that the small advance eastwards on the French coast from the Jaudy estuary to St. Quay Portrieux (less than 50 km) has taken place over some nine years the marked retardation to spread (considered to be due to the large tidal range) in the Gulf of St. Malo is emphasized. Vectors may ultimately carry the species to the ports so that the Cherbourg-Brittany hiatus is bridged but it must also be stressed that the exposed coast between many of the estuaries will tend to hinder spread by marginal distribution. The extension on the western coast of France is much greater and has taken place at a far greater rate--from St. Brevin-l'Ocean to Les Sables d'Olonne (100 km) in three years; this might have been expected with the increasing population density to the north and the presence of small harbours with much fishing activity along this coast. Progress south from Los Sables d'Olonne may be slow: there are large stretches of sand. It is perhaps surprising that it" has not reached La Rochelle where it would find conditions favourable. Further south the long sandy C6te des Landes will provide a very pronounced bar to marginal dispersion but if it became established in the Basin d'Arcachon one would expect it--like Balanus improt, isus--to flourish ; nevertheless, southwards the long sandy coast from there to near the Spanish border will again retard the spread. Consolidation in the bays and estuaries of north-west Spain would have most certainly been expected. Eastward expansion on the north coast is retarded by the physical character of the shore. Beyond Villaviciosa the exposed coast has steep cliffs and jutting headlands with few semi-enclosed estuaries or large harbours. There has been no expansion southwards from S~.o Martinho do Porto for several years. Here again the long sandy coast and the exposed Peniche peninsula may prove an insuperable barrier to marginal dispersion. If carried by vector to Lisbon ElmhTius would be expected to flourish in the Tagus estuary. SUMMARY An account is given of some observations on Elminius modestus Darwin along the coasts of south and south-west Europe including northern France, Spain and Portugal. The consolidation and extension of the immigrant are discussed.
30
BARNES~ H. AND BARNES, MARGARET REFERENCES
BARNES, H. and BARNES, M. (1960) Recent spread and present distribution of the barnacle Elminhts modestus Darwin in north-west Europe. Proc. zool. Soc., Lond. 135, 137-145. BARNES, H. and BARNES, M. (1961) Recent spread and present distribution of the barnacle Elminius modestus Darwin in south-west Scotland. Glasg. Nat. 18, 121-129. BisHoP, M. W. H. and CRISP, D. J. (1958) The distribution of the barnacle Elminius modestus Darwin in France. Proc. zool. Soc. Lond., 131, 109-134. BISHOP, M. W. H., CRISP, D. J., FISCHER-PET'rE, E. and PRENANT, M. (1957) Sor l'ecologie des cirripedes de la c6te atlamique frangaise. Bull. lnst. Oceanogr. Monaco, No. 1099, 12 pp. CRISP, D. J. (1959) A further extension of Elminius modestus Darwin on the west coast of France. Beaufortia, 7 (82), 37-39. FISCHER-PmTTE, E. and FOREST, J. (1961) Nouveaux progres du cirrip/~de austral Elmhzhts modestus Darwin sur les c6tes atlantiques fran~;aise et ib6riques. Crustaceana, 2, 293299. FISCrtER-PIEX'rE, E. and PRENANT, M. (1956) Distribution des Cirripedes intercotideaux d'Espagne septentrionale. Bull. Centre fit. Rech. sc. Biarritz, 1, 7-19. FISCHER-PIETTE,E. and PRENANT,M. (1957) Quelques donnees ecologiques sur les Cirripedes intercotidaux de Portugal, de l'Espagne du sud et du Nord du Maroc. Bull. Centre F_.t. Rech. sc. Biarrit z, 3, 361-368. KUHL, H. (1963) Die Verbreitung yon Elminius modestus (Cirripedia Thoracica) an der deutschen Kiiste. Crustaceana, 5, 99-111.