The marine algal flora of Angola: its distribution and affinities

Bor. J. Linn. SOC., 70: 307-324. With 2 figures

June 1975

The marine algal flora of Angola: its distribution and affinities G. W. LAWSON, F.L.S.

School of Plant Biology, University College of North Wales, Bangor

D. M. JOHN Department of Botany, University of Ghana, Legon, Ghana

AND

J. H. PRICE, F.L.S.

Department of Botany, British Museum (Natural History), Cromwell Road, SW 7

Accepted f o r publication January 1975

Angola has previously received little attention from marine phycologists. Thirty known papers mention marine macro-algae and together list less than 5 0 species. This paper deals with the results of a survey carried out during January and February 1 9 7 4 ; the number of reported species is now more than doubled. The species characterizing the littoral zones of rocky shores in this country are largely also to be found along the Guinea Coast, although minor variations do occur. The affinities of the Angolan marine algal flora are overwhelmingly with the Gulf of Guinea flora; there is a small but distinct transitional element, such as Plocamium beckeri, P. suhrii and Acrosorium maculatum, confined to localities in the south of Angola.

CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . . 307 Special features of the coast of south-western Africa . . . . . . . . . . 309 Distribution . . . . . . . . . . . . . . . . . . . . . . 309

Vertical distribution . . . . . . . . . . . . . . . . . 309 Zonation under sheltered conditions 3 1 0 Zonation under moderately sheltered conditions 31 1 Zonation under moderately wave-exposed conditions 313 Zonation under wave-exposed conditions . . . . . . . . . 31 7 General features . . . . . . . . . . . . . . . . . 319

Horizontal distribution . . . . . . . . . . . . . . . . . 321 Acknowledgements . . . . . . . . . . . . . . . . . . . . 3 2 3 References . . . . . . . . . . . . . . . . . . . . . . 3 2 4

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INTRODUCTION

The coastline of Angola, which lies entirely within the tropics and stretches for about 1200 km from about 6" to 17' south, has in the past received little

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3 08 G. W. LAWSON ET AL.

attention from phycologists. We were, in fact, able to locate a total of 30 papers dealing with the algae of Angola; some of these date back to the late 19th century and together they list less than 50 species. Figure 1 shows the localities at which surveys and collections were made during January and February 1974. These localities are numbered 1 to 22 and the appropriate number is given in parentheses after the name of each locality in the account that follows. The littoral was examined in each case, and the sublittoral whenever conditions were suitable for SCUBA diving.

The Survey was intended to augment knowledge of the algal flora of Angola. Other objectives were: (1) to obtain information on the vertical zonation of species present and to assess its relationship to the situation in other known parts of the African coast; and (2) to investigate the phytogeographical distribution of these species. The latter two points are the primary concern of the present paper.

Figure 1. Map of Angola showing the localities visited during this survey. Inset indicates the position of Angola in relation to the rest of Africa.

1, Ponta do Pinda; 2, Praia Azul; 3, Praia Arnklia; 4 Baia de Mocamtda; 5. Ponta do Girhul; 6, Praia das Conchas; 7, ChapOu Armado; 8, Sio Nicolau; 9, Cuio; 10, Caotinha; 11, Ponta do Sombreiro; 12, Praia Sio Antonio; 13, Baia de Benguela; 14, Praia Egito; 15, Nova Redondo; 16, Pono Arnbbim; 17, Barra do Cuanza; 18, Corirnba (Morro dos Veados); 19, Ilha de Luanda; 20, Cacuaco; 21, North of Cacuaco (jetty); 22, Ponta Spilirnberta.

MARINE ALGAL FLORA OF ANGOLA 3 09

SPECIAL FEATURES OF THE COAST OF SOUTH-WESTERN AFRICA

Ekman (1953) has classified the littoral faunas of the world into four provinces-arctic-antarctic, boreal-antiboreal, warm temperate and tropic. Hedgpeth (1957) has mapped these littoral provinces, and his map shows that in almost all parts of the world the boreal-antiboreal is separated from the tropic by the warm temperate; the exception is South West Africa (Namibia), where the boreal-antiboreal abuts directly on to the tropic. This is the area within which the cold Benguela Current from the south turns outwards into the Atlantic, leaving the coast to the warmer Guinea Water. The location where this occurs is not a permanent fixture but moves further south during the southern summer and retreats northwards during the southern winter. The 24" C sea-surface isotherm, for example, moves south from just below the equator, reaching between Benguela and MoqamCdes, its most southerly limit, from January to April.

Hedgpeth's map shows that the transition between the boreal-antiboreal and tropic faunal provinces occurs a t about the northern limit of South West Africa. Phycologically it is certainly true that some distinctly colder water forms such as Cladophora mirabilis (C.Ag.) Kutz., Laminaria schinzii Fosl., Iridaea capensis J.Ag., Chondria capensis (Haw.) Falkenb. and Tayloriella virgata (C.Ag.) Papenf. are found as far north as Swakopmund (22' 41' S), i.e. just within the "tropics", although many other colder-water species have dropped out by this latitude. Penrith & Kensley (1970b) have recently reported many such colder-water algae further north at Rocky Point (18" 59' S), still in South West Africa. In our survey we were able to reach as far south as Porto Alexandre (1 5" 45' S), although the collections and surveys there were actually made from the rocky area at the Ponta do Pinda (l), a few kilometres to the north. Porto Alexandre itself is predominantly on sand and, being a fishing port and sheltered from wave-action, is highly organically polluted.

The coastline of Angola consists mainly of sandy beaches interspersed with extensive rocky areas. Frequently, the only rock available for algal attachment consists of massive boulders fallen from the often high cliffs and lying embedded in the sandy beaches. Wave-action, as on most other parts of the West African coast, is generally strong, but there are a good many bays that afford some degree of shelter and a few that are very sheltered.

Tides are semi-diurnal and mean heights do not vary very much throughout Angola. Thus the mean figures for Luanda in the north, MoqamCdes in the south, and Benguela between the two, are identical: mean high water springs 1.7, mean high water neaps 1.4, mean low water neaps 0.6, and mean low water springs 0.5, all in metres above Chart Datum.

DISTRIBUTION

Vertical distribution

The patterns of littoral zonation developed along the coast of Angola show considerable variation among the 22 localities that were examined. These differences are due to a number of factors, acting alone or in combination. The type and texture of the rock and its aspect, slope and configuration all have some effect on the pattern of zonation. The degree of sand abrasion, itself


dependent on the strength of the wave-action and the local presence and quality of sand, often exerts a significant effect. A factor that seems to be of overriding importance in the composition and vertical extent of zones is the amount of exposure t o wave-action. For this reason the shores examined have been roughly divided, according to the amount of wave-action they receive, into arbitrary exposure groups. The terminology employed to characterize zones is that of Lewis (1961).

Zonation under sheltered conditions Undoubtedly the most sheltered locality we investigated was Morro dos

Veados (18), just south of Luanda. Here a wide and long arm of the sea, running roughly south-west to north-east, is limited on the southern and western sides by a sand bar allowing the sea to enter and leave only at the north-eastern end. Although the tidal current may be quite strong, the extent of wave-action in the Corimba is negligible, giving a lagoon-like character t o the area, especially in some parts where sandy or muddy beaches are lined by the mangroves Rhizophora mangle L. or more rarely Avicennia africana P. Beauv. Rock is not common; what little there is, as at Morro dos Veados, consists chiefly of consolidated marine sediments, which are often heavily undercut, and of some large boulders of the same material lying on the muddy or gravelly shore.

The mangroves themselves form a suitable substratum for many of the algae that can grow under such conditions. On the landward side there was often a distinct zonation on the prop roots of Rhizophora. Just above the point where the root enters the mud was a greyish zone, about 15 cm high, of Bostrychia binderi Harv. mixed with B. tenella (Vahl) J.Ag.; above occurred a somewhat narrower zone (about 10 cm) of Rhizoclonium implexum (Dillw.) Kutz. In parts where there was a constant flow of water due t o slow drainage at low tide, the larger Rhizoclonium africanum Kutz. accompanied R. implexum, and below the Bostrychia was a low mat of Murrayella periclados (C.Ag.) Schm. Above these algal girdles the prop roots were rather bare except for occasional Littorina angulifera Lam. over about 3 5 cm, although barnacles (Balanus amphitrite Darwin), some oysters (Ostrea tulipa Lam.), and Thais haerpostoma L. covered this region of the roots of the more seaward mangroves. Above approximately the level of high water fruticose lichens (Rocella sp.) were abundant, occurring over the 3 to 4 m up to the tops of the trees.

On the nearby low undercut cliffs, a narrow Littorina zone and a wider barnacle zone were present and in the latter a low “turf” of Lophosiphonia reptabunda (Kutz.) Kylin or Murrayella periclados with some Hildenbrandia prototypus Nardo occurred. In less shaded places Ulva lactuca L. and Boodlea composita (Harv.) Brand were found in the lower eulittoral.

Ulva was also found to continue down into the gently sloping sublittoral, where it was accompanied by large amounts of Acanthophora muscoides (L.) Bory, Hypnea cervicomis J.Ag. and the sea grass Halodule wrightii Asch., which formed extensive “meadows” in shallow water. Also present were small amounts of Gracilaria dentata J.Ag. and Griffithsia tenuis C.Ag. At about half a metre below the low tide level the character of the sublittoral changed somewhat due to the large number of empty oyster and other shells present.

MARINE ALGAL FLORA OF ANGOLA 31 1

Here, ascidians and sponges were very common, with plants of Acanthophora muscoides and, more rarely, lithothamnia growing on the shells.

Zonation under moderately sheltered conditions In contrast to the very sheltered conditions in the Corimba described above,

there exist on the coast of Angola a number of localities that could be described as moderately wave-sheltered.

The most northerly locality that can be included in this category was Cacuaco (20), only a short distance north of Luanda. Although Cacuaco is a projecting point, the sublittoral slopes away gradually and offshore rocks apparently prevent the development of strong waves, at least at low water. Low, often flat-topped, rocks protrude through the sand in the upper part of the shore and through the mud at lower levels.

A littoral fringe was represented on the upper and inshore rocks by numerous large specimens of Littorina punctata Gmelin and the upper limit of the eulittoral was occupied by a fairly large population of Chthamalus dentatus Kr. In the lower part of this latter band were patches of short red algal "turf" of Gelidium corneum (Huds.) Lamour., and on flat-topped rocks protruding through the sand, just a little above low water, was a carpet of Enteromorpha. At only a slightly lower level, but standing in the water and subject to gentle wave-action, were rocks that carried a much richer growth of algae. The upper surfaces, largely drying out a t low water, were dominated by Centroceras clavulatum (C.Ag.) Mont., whilst the edges and sides also supported Gigartina acicularis (Wulf.) Lamour., Boodlea composita, Gracilaria dentata, G. verrucosa (Huds.) Papenf. and species of Ceramium, with Bryocladia thyrsigera (C.Ag.) Schm. dominating at somewhat lower levels and Hildenbrandia prototypus in the crevices. On such rocks Padina australis Hauck, Gelidium crinale (Turn.) Lamour., and Spyridia clavuluta Kutz. were common at about the level of low water, with Cryptonemia luxurians C.Ag. under overhanging rocks.

The outer rocks at Cacuaco, although at about the same height as those described above, were somewhat more wave-exposed, and growing on them were Rhodymenia pseudopalmata (Lamour.) Silva, Pterosiphonia pennata (Roth) Falkenb. and Polysiphonia denudata (Dillw.) Kiitz., with rather larger plants of Cryptonemia luxurians. At a slightly lower level was a zone of gorgonians, supporting algae such as Bryopsis plumosa (Huds.) C.Ag., Clado- phora albida (Huds.) Kutz., and Hypnea musciformis (Wulf.) Lamour.

Another moderately sheltered locality, midway along the Angolan coastline, is the rocky point at the western end of Praia Sio Antonio (12), in the southern inshore reach of the Bay of Benguela. Here shelter is due partly to the arms of the bay and partly to the very gently sloping rocks in the sublittoral. The sandstone cliffs drop down sharply to a beach which is sandy in places but is more often composed of large boulders resting on a flat-bedded shale.

Where the rocks stood high enough for it, a littoral fringe zone was represented by Littorina punctata and a poorly developed black band of Entophysalis deusta (Menegh.) Dr. & Daily. Below this the Chthamalus subzone was narrow but well developed, and on the outer rocks the barnacles were coloured bright green. Algae were poorly represented in the lower eulittoral, and the encrusting forms Ralfsia expansa (J.Ag.) J.Ag. and Hildenbrandia

312 G . W. LAWSON ET AL.

prototypus predominated, the former on smaller boulders and the latter on more continuous rock.

Bachelotia antillarum (Grun.) Gerl. formed a mat on the flatter rocks, and Corallina sp. and Boodlea composita were sporadically present, whilst Gelidium also occurred on the outer rocks. A much better development of algae existed in the sublittoral fringe, where a mixed “turf” mainly of Hypnea spinella (C.Ag.) Kiitz. and Centroceras clavulatum, but including smaller quantities of Hypnea musciformis, Cladophora prolifera (Roth) Kutz., Ernodesmis verticil- lata (Kutz.) Bdrg., Padina vickersiae Hoyt, P. tetrastromatica Hauck, Bryopsis balbisiana Lamour. ex C.Ag. and Colpomenia sinuosa (Roth) Derb. & Sol., was found. Many of these species were also represented in the thick layer of drift weed on the sandy beach to the east in which Hypneu predominates, presumably the species Palminha, Torres & Granger (1963) have referred to as H. benguelensis. Echino metra lucunter L. was rather sparsely present in the sublittoral fringe.

The centre of the bay at the fishing village of Cuio (9), about 70 km south of Benguela, is another locality that could be regarded as moderately sheltered from wave-action, although less so than those described above. Here sandstone rocks protruded through the sand and bore from above downwards a Littorina zone, a zone of Chthamalus dentatus accompanied by the limpet Patella safiana Lam., and a low algal “turf” of rather closely packed and homogenous appearance; this homogeneity disguised the fact that the turf was made up of a number of algae, including Centroceras clavulatum, Gelidium versicolor (Gmel.) Lamour. and species of Champia, Ulva, Corallina, Polysiphonia and Gelidium. On slightly more exposed rocks Entophysalis, and below it a few oysters, were present in the littoral fringe, and on flatter rocks in the eulittoral was a sparse brown “turf” of Giffordia rallsiae (Vick.) W.R. Taylor, mixed with some Bachelotia antillarum. The sublittoral fringe was dominated mainly by sedentary animals such as bryozoans and some corals, although a few algae such as Pterosiphonia and Nitophyllum were sporadically present.

The beach at Praia Amelia ( 3 ) , a few kilometres south of Mogam&des, consisted of sand with smooth flat protruding rocks of insufficient height for a littoral fringe or an upper eulittoral subzone to develop. The highest of these rocks were covered by Enteromorpha flexuosu (Wulf. ex Roth) J.Ag. subsp. flexuosa J.Ag. and those lower down carried a wide and very slippery band of the blue-green alga Microcoleus lyngbyaceus Gomont , in which occurred odd tufts of such algae as Caulacanthus ustulatus (Mert.) Kutz. and Chaetomorpha antennina (Bory) Kiitz. Hildenbrandia prototypus and Basispora africana John & Lawson formed circular crusts, especially in shallow depressions that retained water. In the sublittoral fringe the blue-green algal zone was replaced by a fine red felt largely of Polysiphonia subtilissima Mont. On somewhat more exposed rocks nearby, Chthamalus and lithothamnia were fairly common, with Ralfsia expansa on the upper lithothamnia and Jania crassa Lamour. in mid-tide-level pools. The fine red algal felt was present to some extent directly on lithothamnia but more especially on the large limpet Patella sufiana, where it grew along with Gelidium pusillum (Stackh.) Le Jol. var. pulvinatum (C.Ag.) J . Feldm. (Correctly G. crinale (Turn.). Lamour.-Dixon, pers. comm., 1974). In the more exposed gullies of the sublittoral fringe were Halimedu tuna (Ellis &

MARINE ALGAL FLORA OF ANGOLA 3 1 3

Soland.) Lamour., Cladophora prolifera, C. albida (Huds.) Kiitz., Polysiphonia subtilissima, Dictyota dichotoma (Huds.) Lamour. and Corallina sp.

The most southerly of the localities visited that might be described as moderately sheltered was the north side of Ponta do Pinda (l), about 7 km north of Porto Alexandre. Here high sandstone cliffs gave a good deal of shade to the mixed rocky and sandy beach.

The littoral fringe was dominated by Littorina punctata, but Entophysalis deusta and some Enteromorpha intestinalis (L.) Link subsp. compressa De Silva & Burrows occurred where there was a good deal of shade, as on the cliff face itself. In the lower part of the littoral fringe and extending downwards a little to overlap into the Chthamalus subzone was a band of ?Entocladia testarum Kylin, appearing as a green coloration of the rock surface. A patchy band of Caulacanthus ustulatus occurred in the Chthamalus subzone, with limpets and occasional oysters. Below the lower limit of the barnacles, and often extending down to the sand, was a “turf” of Gelidium pusillurn var. pulvinatum, growing especially on the landward and vertical sides of rocks. Its place was occasionally taken by a mat of a Corallina species accompanied by mussels, particularly in wave-exposed channels. Locally, limpets (Patella safiana) with a covering of Gelidium pusillum var. pulvinatum alternated with patches of Corallina. On rocks standing on sand, where there was much abrasion, the Corallina mat gave way to Ralfsia, then sometimes to a fine red felty covering of Polysiphonia, and finally to bare rock.

Zonation under moderately wave-exposed conditions About half of the localities studied in Angola can be included under this

heading. The northernmost of these is Ponta Spilimberta (22), just south of the Barra do Dande. Here, the cliffs are high and there is often a smooth platform at about the level of the littoral fringe. Surprisingly enough, however, no specimens of Littorina punctata were observed and only a few Siphonaria were present on the outer part of the platform, with Chthamalus appearing at about its seaward edge, A prominent zone of Caulacanthus ustulatus occurred on the vertical face below the barnacles, and then a green band of Bryopsis and Vaucheria extended from the lower limit of Caulacanthus downward into the lithotharnnia subzone. On slightly undercut vertical faces subject t o much spray an algal “turf” including Centroceras clavulatum, Ceramium mazatalense Dawson and Herposiphonia tenella (C.Ag.) Ambronn occurred as high as the upper eulittoral.

Seaward of the platforms described above, where wave surge is strong, are large broken blocks of rock. These blocks were covered by a dense growth of seaweeds including many species representing the lower eulittoral. On the seaward faces of the blocks the commonest algae were Bryopsis plumosa, Chaeto morpha an tenn ina, Colpomen ia sin uosa, A mphiroa beau voisii Lamour., Jania fastigiata Harv., Hypnea musciformis, and Bryocladia thyrsigera. The somewhat more sheltered landward-facing sides of these rocks bore Gracilaria dentata, Gelidiopsis variabilis (J.Ag.) Schm., Gymnogongrus nigricans P.Dang. and a “turf” of a small Gelidium sp. At lower levels Pterosiphonia pennata, Rhodymenia pseudopalmata and Heterosiphonia wurdemanni (Bailey ex Harv.)

314 G. W. LAWSON ET AL.

Falkenb. were present, and from rather shaded parts Cryptonemia luxurians and Spermothamnion were collected.

At Luanda (19), a solid substratum for marine life is provided by the sea wall and a series of groynes, composed of large irregular blocks of stone, that run along the outer side of the island (Ilha de Luanda) that protects the harbour. Viewed from a distance three distinct colour zones were seen on these artificial structures: an upper darker zone of almost bare rock, where there was little life other than Littorina punctata, gave way below to a whitish zone formed by the barnacle Chthamalus dentatus, and below that again was a blackish zone of mussels (Perna perna L.) with the dark-coloured “algal turf” of the lower eulittoral, in which Gelidium pusillum was a prominent component.

In more detail, the Chthamalus subzone included about the middle a band of oysters (Ostrea tulipa) with the more usual limpets (Siphonaria grisea Gm., Patella spp.) scattered throughout. Below Chthamalus, the mussels were accompanied by Balanus tintinnabulum L. and Patella safiana. Some algae, such as Polysiphonia subtilissima and Chaetomorpha antennina, grew on the mussels, but most formed a low “turf” on the rock itself. This “turf” included Gelidium pusillum, Centroceras clavulatum, Chaetomorpha antennina and Herposiphonia tenella, as well as smaller amounts of Sphacelaria furcigera Kiitz. and Ceramium, Cladophora and Enteromorpha species. In places where mussels were absent the rock was red in colour due to the encrusting alga Rhodophysema africana John & Lawson. The algal “turf”, mixed with patches of lithothamnia, stretched below the mussels and gave way first to a rather curious band of Ulva rigida C.Ag. and finally to another greenish band that included species of Chaetomorpha, Cladophora and Enteromorpha, with Herposiphonia tenella (C.Ag.) Ambronn var. secunda Hollenb. and Bachelotia antillarum. These last two probably unusual bands may have been due to the heavy abrasive action of the beach sand on which the rocks stand. This is indicated by the fact that on more exposed south-west faces of the breakwaters, the lower rocks were more or less bare or carried only a sparse covering of bryozoans.

On the north side of the Barra do Cuanza (17) is a somewhat undercut low sandstone cliff, standing above a sandy beach through which project low, often flat-topped rocks. Present on the cliffs, especially where there is some shade, was a well-marked band of Entophysalis deusta overlapping in its lower part a Littorina angulifera zone. Chthamalus was very poorly represented and the upper eulittoral subzone was rather bare, but algae were abundant in the lower eulittoral subzone. They included Gelidium pusillum var. pulvinatum, Graci- laria dentata, Cladophora albida, Bachelotia antillarum and Enteromorpha linza (L.) J.Ag. In the sandy layer near the base of the rocks Grateloupia filicina (Lamour.) C.Ag., Gracilaria verrucosa, Bryocladia thyrsigera and Hildenbrandia prototypus formed a covering, and on the outer and more exposed faces of these rocks Gymnogongrus tenuis (J.Ag.) J.Ag., Ulva fasciata Delile, Porphyra sp. and Ralfsia expansa were common. Mussels were also present on the more wave-exposed rocks.

Considerably further south than the Barra do Cuanza are the rocks which were examined at Porto Ambbim (16). Here again, a sandy beach at the foot of the cliffs gives strong abrasive action on the lowermost rocks. On the often almost vertical faces of these beach cliffs the essential zonation was as follows.

MARINE ALGAL FLORA OF ANGOLA 315

Uppermost was a zone of Littorina punctata, with a well developed but fairly narrow black lichen band present within it. The upper eulittoral subzone was dominated by Chthamalus and Siphonaria, with a blue-green colour to the rocks indicating a zone of Entophysalis. Ulva fasciata and mussels dominated the lower eulittoral subzone, with a rather distinct fringe of Caulacanthus ustulatus at the upper margin. The Ulva zone included many other algae such as Gelidium pusillum var. pulvinatum, Grateloupia filicina, Champia parvula (C.Ag.) Harv., Bryocladia thyrsigera, Herposiphonia tenella and species of Ceramium and Polysiphonia. Lithothamnia were not found on the beach rocks but were present on higher vertical surfaces. It should be noted that here, as on many sandy beaches with protruding rocks, there is little chance for the development of a sublittoral fringe.

At Egito (14), massive sandstone cliffs form a slight bay into which a river debouches centrally through a beach of large cobbles and boulders, with sand near low water. The upper cobbles and boulders had a brown shiny coating due to a film of diatoms, with Enteromopha flexuosa subsp. flexuosa appearing lower down. The lowermost rocks, especially those on the sandy beach, were rather bare round the sides, no doubt due to sand abrasion, but the tops were covered by patches of Gelidium pusillum var. pulvinatum, Bryocladia thyrsigera, Grateloupia filicina, some Hypnea and Polysiphonia subtilissima. There was a considerable amount of drift, in the bay, of plants not found in the littoral zone, suggesting that there must be extensive offshore populations in the vicinity.

The point a t the south side of Egito Bay is Cab0 Egito, and there conditions are somewhat more exposed. The cliff faces are more or less vertical, and at the base of the cliffs are flat platforms about half a metre above low water. The usual Littorina punctata fringe was present on the cliff faces, although the barnacle subzone was poorly developed and Siphonaria was commoner. Below this was a Caulacanthus ustulatus band with clumps of Gelidium and Ulva fasciata, followed at somewhat lower levels by Chaetomorpha antennina and some Grateloupia filicina. On the platforms was an extensive mat of Corallina and Ceramium gracillimum (Kiitz.) Griff. & Harv. var. byssoideum (Harv.) Mazoyer with much epiphytic Callithamnion, and at the inshore margins of the platforms were patches of Grateloupia, Bryocladia and Hypnea. The outer, more exposed edges of the platforms were covered by lithothamnia, together with Gracilaria dentata, Rhodymenia pseudopalmata, Lobophora variegata (Lamour.) Womersley and Griffithsia opuntioides J .Ag., but Echinometra was only rarely found.

Rocks at Caotinha (lo), a locality lying to the south of Benguela, were very much weathered forming innumerable depressions and crannies for the establishment of marine organisms. Although some small sandy bays are present among the rocks, it seems probable that the degree of sand abrasion would be appreciably less than at many other localities visited.

Zonation from above downwards was as follows. The uppermost organism was Littorina punctata and in the Littorina zone was a band of black lichen; immediately below, especially in shaded parts, a "turf" of Bostrychia binderi included Lophosiphonia reptabunda and very small plants of Ulva, with Rhizoclonium riparium (Roth) Ham. in its lower parts. A band of the oyster Crassostrea cucullata Born. lay immediately below the Bostrychia, followed by

3 1 6 G . W. LAWSON ET A L .

a narrow zone bare except for Littorina punctata; below that was the beginning of a zone of Hildenbrandia prototypus, giving a distinct dark red colour to the rocks. At about the same level, patches of Gelidium pusillum appeared, and these carried on down into the sublittoral. Overlapping the Hildenbrandia band in its lower part was a rather narrow band (about 30 cm in vertical height) of Chthamalus dentatus, accompanied by other animals including Littorina punctata in the upper parts, Siphonaria throughout and Patella safiana in the lower parts. Odd tufts of Chaetomorpha antennina occurred among the barnacles and there was a definite band of Caulacanthus ustulatus at the lower range of the barnacles, extending somewhat below them. Shallow lithothamnia-lined tidepools at this level contained patches of Microcoleus lyngbyaceus together with another blue-green alga Schizothrix calcicola Gomont. The lower limit of the barnacles was rather sharply defined by a thick growth of ridged and tortuous lithothamnia, which had a yellow appearance in the upper part of the subzone due to a covering of the coccoid blue-green alga Anacystis dimidiata (Kutz.) Dr. & Daily. Other algae in this lithothamnia subzone included Gelidium versicolor and Ralfsia expansa, whilst the lithothamnia were burrowed into by the bivalve Lithophaga. The band of tortuous lithothamnia had a sharp cut-out near low water, where it was replaced by flat species of lithothamnia. The meeting point of these two lithothamnioid growth forms can be regarded as the upper limit of the sublittoral fringe; it was also the upper limit of Echinometra Iucunter and of a fine “algal turf’’ including species of Gelidium, Polysiphonia and Champia. With slightly more shelter, other species such as Colpomenia sinuosa and a species of Corallina grew on the lithothamnia.

In the sublittoral, lithothamnia and Echinometra extended down for about 2 to 3 m. Below this, animals (notably gorgonians and polyzoans), with some Amphiroa beauvoisii, were dominant down to about 6 m, where the bottom became largely sandy with emergent ridges and knolls of rock. Some plants of Flauhaultia appendiculata Born. were found from about 2 m down, but the larger plants occurred at deeper levels of 5 to 10 m. On the rather more sheltered northern side of Caotinha, many more algae were found in the sublittoral. A Gelidium-dominated carpet of algae included such species as Amphiroa beauvoisii, Hypoglossum abyssicolum W.R.Taylor, Herposiphonia tenella and rarely some ?Callithamnion hookeri (Dillw.) S.F.Gray. Other plants found included Rhodymenia pseudopalmata, Dictyota dichotoma, Ptero- siphonia parasitica ( Hu ds. ) Falkenb., Gra teloupia filicina, Lo bophora variegata, and species of Cladophora, Polysiphonia, Ceramium, Ulva and Peyssonnelia. A similar carpet of algae having many of the plants in common was found down to 8 m at Ponta, Bongue, a t the south side of the bay a t Cuio (9). At Caotinha, in small depressions at about 6 to 8 m depth, were small plants of Sargassum vulgare C.Ag., whilst Codium decorticatum (Woodw.) Howe was collected from deep sheltered gullies. Flauhaultia appendiculata, one of the few algae of exposed parts, was also common in a reproductive state in sheltered conditions. Rather surprisingly, Plocamium and Halimeda were not found, although they were often common subtidally in more southerly localities.

The rocks at Praia Azul (2), just south of MoqamEdes, might also be described as moderately exposed t o wave-action. A small cliff behind the sandy beach allowed for the development of higher zones than at the nearby Praia


Amelia. Here, a belt of Entophysalis deusta was present in the littoral fringe, accompanying Littorina punctata. Below, the Chthamalus subzone was well developed, and patches of Caulacanthus ustulatus occurred in its upper parts. A somewhat bare area lay below the barnacles and was followed by the main algal zone. This consisted of a “turf” of Gyrnnogongrus nigricans mixed with Gelidium pusillum var. pulvinatum and Ulva lactuca. Small amounts of Champia parvula and Polysiphonia subtilissirna were also found and there was some Hildenbrandia prototypus between the patches of “turf”. On rocks immediately above the sand a large amount of Grateloupia filicina was present, accompanied by some Gymnogongrus nigricans and by Acrosorium rnaculatum (Kutz.) Papenf.

Ponta do Pinda (l), just about 7 km north of Porto Alexandre, the southernmost point visited, could be described as moderately wave-exposed on its southern side. The rocks standing on a coarse sandy beach were very much weathered. The upper parts of the rocks bore first a band of black lichen, then a greenish band of ?Entocladia testarum above the Chthamalus subzone. The barnacle subzone was rather narrow and many algae were present in it including a well-developed band of Caulacanthus ustulatus, Ulva rigida, soft hemi- spherical tufts of Bryopsis corymbosa J .Ag., and an occasional Porphyra plant. The lower eulittorial was very densely populated by mussels, lithothamnia, and a mixture of small algae including Champia parvula, Herposiphonia tenella, Pilayella littoralis (L.) Kjellm., Ceramium diaphanum (Lightf.) Roth, Bachelotia antillarum and Polysiphonia subtilissirna-the last three often growing directly on the mussels.

Zonation under wave-exposed conditions At Sgo Nicolau (8), the point at the southern side of the bay was examined.

Here the shore, composed of very large boulders and the rocky cliffs from which they have broken off, is very exposed to wave-action.

As in all wave-exposed places, the zonation was vertically much widened. The organisms of the littoral fringe included Littorina punctata, a few oysters, some black lichen, and occasional Nerita senegalensis Gm. in its lower parts. Chthamalus was fairly widespread, with some animals in the lower part of the littoral fringe and the rest scattered in a band below the littoral fringe; the lower band can be referred to as the “pink band”, due to the preponderance of lithothamnia. In this pink band Bryopsis corymbosa was common and Caulacanthus formed a patchily continuous mat. Below the pink band was a yellow band in which the colour of the lithothamnia was masked by the blue-green alga Anacystis dimidiata. Other algae in the yellow band included an Ulva and small clumps of Grateloupia filicina. In the lower part of the yellow band, Gelidium versicolor was common, as were mussels, especially at the seaward edges of the rocks. Below came a second pink band, in this case of lithothamnia with a tortuously ridged surface, containing Echinometra lucunter.

With some shelter from direct wave-action, but in continuously wet conditions, erect and very tough plants of Grateloupia filicina were frequent, and above them were attached some Chaetomorpha antennina and Ceramium tenuissirnurn (Roth) J.Ag. In some places Caulacanthus seemed to be divided by Giffordia rallsiae and Pleonosporium into an upper and a lower band.

a4


Locally, populations of Porphyra were present on the tops of rocks where there was heavy fall of spray. At lower levels, Lobophora variegata occurred on flatter rocks subject to even less wave-action.

In the immediate sublittoral at Sio Nicolau, Echinometra was abundant on the lithothamnia in both exposed and less exposed places; these organisms continued down to about 3 m depth. Below this, at levels from 3 to 6 m depth, and on more or less continuous rock, Plocamium suhrii Kutz. and Dictyota dichotoma were abundant, together with small amounts of Halimeda tuna. On vertical surfaces occurred a Pleonosporium with a bluish iridescence, sometimes accompanied by Hypoglossum abyssicolum. At greater depth, lithothamnia were still plentiful, together with Peyssonnelia inamoena Pilg.

Very similar zonation was found on wave-exposed rocks at Chapku Armado (7), where the colour bands were even more distinct. The uppermost of these, an orange-brown band, contained Littorina punctata and oysters. Black lichen was also present but extended down into the yellow band below. Here Porphyra was commbn, together with some Hildenbrandia prototypus and a few barnacles. The pink band below harboured many limpets, as well as Caulacanthus ustulatus and Polysiphonia subtilissima. Below this was a second yellow band of the ridged tortuous lithothamnia, together with Gelidium versicolor and limpets. With some shelter, Corallina sp. and Peyssonnelia capensis Mont. were present in this band.

In the sublittoral lithothamnia extended to the lowest depth surveyed (10 m) and Echinometra dominated down to about 2 m. The more exposed parts of the sublittoral contained Halimeda tuna, Flauhaultia appendiculata, Cryptonemia luxurians and bushy clumps of Plocamium suhrii. With some shelter many more species were found in the sublittoral; these included Gelidium pusillurn var. pulvinatum and, in sandy places, a mat of Corallina. Other plants present were Plocamium beckeri Simons, Dictyota cervicornis Kiitz. forma pseudobartayresii Kiitz., Halimeda tuna, Colpomenia sinuosa, Padina vickersiae and Codium guineense.

At Praia das Conchas (6) there are very weathered rocks. From a flat rock platform the rocks drop down about 6 m to a second platform, which is flooded at high water. A second drop leads to a third platform in the sublittoral. On the upper platform Entophysalis deusta was found to 30 to 40 m from the sea and surrounded shallow dried-out pools filled with salt crystals, whilst Littorina was only present near the seaward edge of the platform. On the vertical drop to the second platform was a belt of Porphyra and oysters, with Chthamalus in the lower part together with some Ulva lactuca. The second platform bore a number of algae including Bryopsis corymbosa, Caulacanthus ustulatus, Gelidium pusillum var. pulvinatum, G. versicolor, Polysiphonia subtilissima and Corallina, whilst lithothamnia occurred at the seaward edge of the platform. Also present on the second platform were barnacles, limpets (Patella natalensis) and in shallow pools Echinometra Iucunter; the main sea urchin zone did not begin until the third platform.

At Ponta do Giriul(5), close to Praia das Conchas and near the lighthouse to the north of MogamCdes, there are very wave-exposed and flat-topped rocks with an almost vertical drop of 3 to 4 m to the level of low water. On the top of these rocks were algae including Bryopsis corymbosa, Enteromorpha


lingulata, Polysiphonia subtilissima and lithothamnia, especially in shallow pools, with Porphyra on the tops of somewhat projecting rocks. On the seaward vertical faces there was usually a band of Porphyra near the top, followed by a whitish zone of Chthamalus and lithothamnia; these were followed downwards in turn by: a yellow zone where the lithothamnia were associated with a layer of the blue-green alga Anacystis; a well-developed zone of mussels with Ceramium gracillimum var. byssoideurn; and finally a pinkish zone of lithothamnia with Balanus tintinnabulum and a sublittoral fringe of the sea urchin Echinometra. The somewhat sheltered vertical faces of gulleys, which were nevertheless exposed to very strong wave surge, had a number of other algae including Ulva fasciata and Chaetomorpha antennina near the tops, with somewhat lower down Grateloupia Jilicina and Gelidium versicolor covered by many epiphytes, such as Ceramium and Fosliella.

The immediate sublittoral at Ponta do Giraul and at Praia das Conchas was almost devoid of algae, other than lithothamnia, to depths of about 2 to 3 m. Echinometra lucunter, however, was very common but quickly disappeared below. Rock oysters were also common at this level and lower; they were not obvious, as they were covered by lithothamnia and animal growths. On the steeply sloping rocks in this general area animals dominated down to 8 to 10 m, whilst below this depth the cliff gave way to a series of rocky ledges and finally to sand at about 18 m. Isolated clumps or occasionally more extensive patches of Plocamium spp., Arnphiroa beauvoisii, Halimeda tuna and bluish iridescent plants of Dictyota dichotoma were found over much of the depth range surveyed. Fine filamentous and membranaceous reds grew over the often dominant carpet of bryozoans and large gorgonians. These algae included Ceramium tenuissimum, Antithamnion elegans Berth., Callithamnion decom- positum (Grat.) J.Ag., Hypoglossum abyssicolum and Polysiphonia species, whilst on bare rocks and shells were encrusting reds such as Rhodophysema and Peyssonnelia. On the more sheltered southerly side of the Ponta do Giriul the cliff gave way to sand, and towards the beach to a muddy bottom overlain with shell fragments, at progressively shallower depths. With increasing shelter a low “algal turf”, largely consisting of a creeping Gelidium, grew over the mussels and lithothamnia in the lower eulittoral, extending down into the immediate sublittoral. Rock oysters were still present, although Echinometra was now less abundant and another urchin (Eucidaris) was occasionally present. Near the beach, at the base of the cliff, there were low rocks protruding through the mud at a depth of about 6 m covered by a layer of fine silt. On these rocks were found a few small Sargassum plants, occasionally with Codium decor ticat urn

General features In general the patterns of littoral zonation found in Angola (Fig. 2) showed

very strong resemblances to those found on the Guinea Coast. In both, the littoral fringe is dominated by Littorina punctata and contains few algae except for the frequent presence of a blackish band of Entophysalis deusta and species of Bostrychia (B. binderi and B. tenella); sometimes these are mixed with Lophosiphonia reptabunda and Murrayella periclados. especially where there is some shade in deep cracks or under overhanging rocks or trees. One main difference is that, at many localities visited in Angola, the Entophysalis was


7 L F

! 1 -

Figure 2. Diagrammatic representation showing the main features of zonation on the rocky shores of Angola in relation to wave-action.

accompanied by patches of a black marine lichen. Other differences, largely confined to the southern part of the Angolan coast, do occur. For instance, a band of Porphyra is sporadically present in the lower part of the littoral fringe and sometimes extends downwards into the upper part of the eulittoral. Also in the most southerly part of Angola a greenish layer of ?Entocladia testarum occurred over much of the littoral fringe, especially where the rocks were shaded.

The eulittoral zone itself can be subdivided into an upper subzone, arid at low water and dominated by animals, mainly the barnacle Chthamalus den tutus with some oyster and limpets, and a lower subzone, dominated by algae and hardly ever drying out completely at low water. Algae are generally not common in the upper eulittoral but tufts of Ulva and sometimes Chuetornorpha antennina are frequently to be found in both areas. The main difference is that along almost the whole length of the Angolan coast a band of CuuZucanthus ustulatus is almost invariably present in the lower part of the subzone.

The lower subzone of the eulittoral is much more variable and may contain a wide range of algal forms. In the more exposed parts lithothamnia dominate and are overgrown to some extent by other encrusting algae such as Ralfsia expansa, or by a close “turf” of algae; the latter may include creeping Gelidium (both wide and narrow forms) and such plants as Herposiphonia tenella, Centroceras clavulatum, Gymnogongrus nigricans, and several species of Ceramium and Hypnea. A number of animals, commonly mussels, limpets and


the large barnacle Balanus tintinnabulum, are present. With increasing shelter, more and more larger algae are found in the subzone, including such species as Boodlea composita, Bryocladia thyrsigera, Colpomenia sinuosa, Gracilaria dentata, Grateloupia filicina, Rhodymenia pseudopalmata, Ulva fasciata, and several species of Bryopsis, Padina and Jania. A special feature of Angola was the frequency with which Champia parvula was found in the algal "turf" of this subzone in somewhat wave-exposed localities. It was also of note that, except in the north of Angola, the large Gelidium versicolor was often abundant in more wave-exposed situations. One of the more noticeable differences between the coasts of Angola and the Gulf of Guinea occurs in moderately exposed and exposed localities in the former, where the lower subzone is subdivided into an upper band of ridged and tortuous lithothamnia and a lower band of plants with more or less smooth surfaces. The upper band can sometimes be distinguished at distance due to the yellow layer of the blue-green alga Anacystis growing over it, whilst the lower band remains pink; occasionally, this yellow layer extends downward over the smooth-surfaced lithothamnia.

The sublittoral fringe in Angola, as in other parts of West Africa, is not easy to define or to maintain as an ecological reality as it has no reliable indicator. The most constant feature is the presence of the black spiny sea urchin Echinometra lucunter, which is especially abundant where wave-action is strong. Again, a wide variety of algae is present, including Amphiroa beauvoisii, Cryptonemia luxurians, Gelidiopsis variabilis, Pterosiphonia pennata and several species of Dictyota and Peyssonnelia. The most striking difference between Angola and the Gulf of Guinea is the absence from this zone in the former of Dictyopteris, Galaxaura and Caulerpa, and the scarcity of Sargassum, normally the dominant component of the zone on the Guinea Coast, except where there is heavy wave-action. On the other hand some species such as Halimeda tuna, not present in the Gulf of Guinea, were found in this zone in Angola.

It is worth commenting here that several of the zone-forming plants of Angola, notably Porphyra, Caulacanthus ustulatus and Gelidium versicolor, although absent from the Gulf of Guinea are nonetheless present on the West African coast and adjacent islands to the north of the Gulf, i.e. in the Northern as well as in the Southern Hemispheres. For instance, similarly placed bands of Porphyra and Caulacanthus are to be found in both Angola and Sknkgal, and Gelidium versicolor again forms a distinct band in the Canary Islands.

Horizontal distributions

As indicated in the introduction, one of the objects of our survey was to ascertain the extent of penetration of colder water species of algae into Angola and to assess the degree to which, based on algal distribution, it could be regarded as a transition area between the tropic and boreal-antiboreal provinces. I t is necessary therefore to decide which of the 123 species we have thus far identified from Angola can be regarded as characteristic of the Guinea marine algal flora, and which can be referred to the South West African marine algal flora. The former comparison can readily be made as two of us (DMJ and GWL) have been working on the marine algal flora of the Gulf of Guinea for many years, and are very familiar with its composition. For the latter comparison, however, we have had to rely largely on a list of South West


African marine algae kindly supplied by Mr Richard Simons. In this undoubtedly incomplete list, some identifications have been made only to generic level; this must mean that our assessment of the South West African element is likely to be an underestimate.

The distribution, along the Atlantic coast of Africa, of the species making up the Angolan marine flora is illustrated graphically in John, Lawson & Price (1975). The species forming the 3% of the benthic marine algae confined to Angola are apparently not endemics; they occur in other parts of the Atlantic outside Africa. A fairly large proportion of the Angolan marine flora (29%) occurs also along the African coast, both to the north and to the south; these are species of widespread or even cosmopolitan distribution. 58% of the Angolan flora is also found in the Guinea flora but is not present t o the south of Angola. A mere 4% of the Angolan flora is common also t o South Africa and South West Africa, but is absent from the Gulf of Guinea. Again this latter figure is probably an underestimate, but there can be little doubt that the affinities of the Angolan flora are overwhelmingly with that of the Gulf of Guinea. The few species that Angola shares with regions further t o the south indicate a small but distinct transitional element.

The number of species in this transitional element is sufficiently small for each to be considered individually. Caulacanthus ustulatus, Gelidium versicolor and Codium decorticaturn also occur on the West African coast to the north of the Gulf of Guinea. In both the Northern and Southern Hemispheres, the first two are prominent zone-forming species of the littoral, whereas the last is known from the sublittoral. Other species recorded from Angola, but not apparently from further south, similarly occur north of the Gulf of Guinea; they are Bryopsis balbisiana, B. corymbosa, Halimeda tuna, Griffithsia opuntioides, Pilayella littoralis and Pterosiphonia parasitica. The common Porphyra from Angola may be referable to P. capensis Mont., a species known abundantly from South Africa and South West Africa.

Southern affinities were also demonstrated by Plocamium beckeri and P. suhrii; these species were found in abundance in the sublittoral as far north as Siio Nicolau (8). Previously they have been reported in the warmer waters to the east of Cape Agulhas, the southernmost point of South Africa. Simons (in litt., 11.3.74.) has recently detected Plocamium suhrii in the South Atlantic, in a collection of algae from the apex of the seamount Vema, 6 0 m below the sea-surface and about 500 miles west of St. Helena Bay (32" 44' S, 17" 59' E). Another interesting species known from further south and now first reported for Angola is Acrosorium rnaculatum.

These species distributions provide further evidence for transition along the Angolan coastline. Table 1 shows the algae recorded in two or more localities in Angola but absent from the Gulf of Guinea. Clearly such species are confined to the southern half of Angola, and for this reason localities to the north of Egito (14) are omitted.

Our conclusion that there is very restricted penetration of colder water species into Angola from the south is tentative; our visit was made during the middle of the southern summer, when warmer water conditions prevail along much of the Angolan coast. Collections made during the months of the southern winter might reveal a greater number of colder water algae along the southern parts of the coast.


Table 1. The algae found in two or more localities and confined to the southern part of the coast of Angola (Ponta do Pinda to Praia Egito) but absent from the Gulf of Guinea

Algae 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4

- + + - - - - - - + - - - - Acrosorium maculatum Bryopsis balbisiana - - - - - - - + - - - + - - Bryopsis corymbosa Codium decorticaturn _ - - - + - - - - + - + - -

+ - $ - - + - ? Codium guineense - - - - _ _ Corallina sp. + - + - - + + + + + - + - + Cruonopsis sp. Delesseria Sp. - - - - - - - - + - - - + - Flauhaultia appendiculata Gelidium versicolor _ - - - + + - + + + - - - - Gigartinaceae _ - _ _ _ - + + - + + - - - Halirneda tuna - - + - + + + + + - - - - ? Hypoglossum a byssicola + - - - + - - + + + - - - ? Nitophyllum sp. _ _ - - _ - - - - + + - - -

+ - - - + + - + + - - - - -

+ - - - - + - - - - - - - -

_ - - - - _ + - - + - - - -

_ - - _ + - + + + - - - - - - - - - + + + + - - - - - - + - - - - + + + - - - - - - - _ - - _ - - - + + - - - -

- - - - - + + - - - - - - -

Plocamium beckeri Plocamium suhrii Porphyra sp. Pterosiphonia parasitica Ulvella lens

?, Drift plants only; +, present attached

There is a rather surprising absence or scarcity in Angola of a number of

(i) Dictyopteris delicatula ; abundant in the sublittoral fringe and below in

(ii) Sargassum; abundant in the Gulf of Guinea, but only a few small and

(iii) Galaxaura ; several species found abundantly along the Guinea Coast,

(iv) Caulerpa ; as Galaxaura. In a recent series of papers (Penrith & Kensley, 1970a,b; Kensley & Penrith,

1973) on South West Africa and southern Angola, the authors conclude that Mosamtdes (Angola) is well within the tropical West African littoral faunal province; the northern South West African fauna, by contrast, includes a large number of colder water species. The changes in fauna and flora therefore appear to parallel each other, with a fairly abrupt transition occurring on the south-western coast of Africa between Porto Alexandre (15" 48' S) in Angola and Rocky Point (1 8" 59' S) in South West Africa.

important zone-forming algae of the Guinea Coast:

the Gulf of Guinea, but absent from Angola.

poorly developed plants found in Angola.

but absent from our collections from Angola.

ACKNOWLEDGEMENTS

The field work on which this report is based was made possible by a grant from UNESCO which covered the expenses of two of the members (GWL and DMJ), whilst the British Museum (Natural History), London, provided funds


for the third member (JHP). Thanks are due t o the University of Ghana, Legon, which awarded a supplementary grant t o Dr D. M. John. We wish to thank Professor E. Laing, Head of the Department of Botany in the University of Ghana, who allowed us the use of facilities of the Department during our work.

The staff of the Instituto Investigaqiio Cientifica de Angola, Luanda, notably Professor L. A. Grandvaux-Barbosa, Dr M. S. Vasconcelos, Sr R. M. dos Santos and Sr C. A. Henriques, were extremely helpful in providing assistance, transport and laboratory space, and we are deeply indebted t o them. We also wish t o record our thanks to Sr F. de Figueiredo of the University of Luanda, who afforded us valuable assistance in the diving work, and to Professor J. Pinto-Lopez, Head of the Department of Botany at the University.

Dr V. Yoloye, Department of Biological Sciences, University of Lagos, Nigeria, kindly identified many of the animals, and Mr Richard Simons of the South African Seaweed Research Laboratory, Cape Town, provided deter- minations and information on South West African and South African marine algae.

REFERENCES

EKMAN, S., 1953. Zoogeography of the sea. London: Sidgwick & Jackson. HEDGPETH, J . W., 1957. Marine Biogeography. Mem. geol. Soc. A m . , Memoir 67 ( 1 ) : 359-82. JOHN, D. M., LAWSON, G. W. & PRICE, J. H., 1975. Preliminary results from a recent survey of the

marine algal flora of Angola (south-western Africa). Proc. Int. Seaweed Symp., 8: (in press). KENSLEY, B. & PENRITH, M.-L., 1973. The constitution of the intertidal fauna of rocky shores of

Moqarnedes, southern Angola. Cimbebasin (Ser. A), 2: 114-23. LEWIS, J. R., 1961. The littoral zone on rocky shores-a biological or physical entity? Oikos, 12 :

PALMINHA, F., TORRES, L. & GRANGER, R., 1963. Urna alga de provivel interesse econbrnico na Bafa de Benguela (Hypnea benguelensis nov. sp.). Notas mimeogr. Centro Biol. Piscat., Lisboa., 37: [2] +

PENRITH, M.-L. & KENSLEY, B.F., 1970a. The constitution of the intertidal fauna of rocky shores of

PENRITH, M.-L. & KENSLEY, B. F., 1970b. The constitution of the fauna of rocky intertidal shores of

280-301.

1-21 + 121.

South West Africa. Pt. 1. Luderitzbucht. Cimbebasiu (Ser. A), I : 191-239.

South West Africa. Pt. 11. Rocky Point. Cimbebasia (Ser. A), 1 : 243-68.

The marine algal flora of Angola: its distribution and affinities

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