ACTA NATURALIA ISLANDICA

ISSUED BY THE ICELANDIC MUSEUM OF NATURAL HISTORY (NATTURUFRAEDISTOFNUN ISLANDS)

The Museum has published two volumes of Acta Naturalia Islandica in the period 1946-1971, altogether 20 issues. From 1972 each paper will appear under its own serial number, starting with no. 21.

ACTA NATURALIA ISLANDICA is a series of original articles dealing with botany, geology and zoology of Iceland.

ACTA NATURALIA ISLANDICA will be published preferably in English and will appear at irregular intervals.

ACTA NATURALIA ISLANDICA may be obtained: 1: on basis of institutional exchange at Museum of Natural History, P. O. Box 5320, Reykjavik. 2: as separate copies on request (charges including mailing costs) at Snaebjorn J6nsson, The English Bookshop, Hafnarstraeti 4, Reykjavik, Iceland. GENERAL FEATURES OF THE BENTHIC ALGAL Z00:ATION AROUND THE ICELANDIC COAST

General features of the benthic algal zonation around the Icelandic coast

IVKA MUNDA Slowene Academy of Science and Arts, Biological Institute, Ljubljana, Jugoslavia Abstmct. A survey is given of the main features of benthic algal zonation in the south, south west, north west, north and east of Iceland. Differences in the zonation pattern be­ tween the investigated areas seem to be closely correlated to the varying hydrographic con­ ditions around the Icelandic coast. They proved to be most outstanding in the lower littoral zones of exposed, rocky sites, which are in direct contact with the ocean. These differences proved to be less pronounced in the upper and middle littoral levels but rather conspicuous in the tide pools. In the lower littoral, Gigartina stellata-) Callithamn­ ion arbuswla- and Corollina ottiC£nalis belts proved to be outstanding for the south, south west and north west, Halosaccion ramentaceum belts for the north, and Porph'ym linearis-) Chorelaria flagellifonnis- and Acrosiphonia spp. belts for the east. An increase in vertical ex­ tension of the upper littoral Ulothrix-U1'Osporo belts was observed in the northeastwards di­ rection.

Introduction 2 Littoral levels 3 Patterns of algal zonation around Iceland 5 I. South Iceland 5 The coastal area between the rivers blfusa and Thj6rsa 5 Reykjanes peninsula 7 II. South "'West Iceland - Smefellsnes area 8 III. North 'vVest Iceland 11 Dyrafjordur 11 IV. North Iceland 15 SteingTimsfjordur 16 Grimsey in Eyjafjardarsysla 17 V. East Iceland 19 Reydarfjordur 19 Discussion 22 Summary 26 Species new for Iceland 27 List of species mentioned in the test 28 References 32 Explanations of Plates 36 2 ACTA NATURALIA ISLANDICA 21 (1972)

INTRODUCTION

The benthic algal vegetation around the Ice­ Lundenbeck (1892), Davidsson (1897), landic coast is rather heterogenous, reflecting Steenstrup (1840), Faber (1819) and others. the different hydrographic conditions, created Recent collections of benthic marine algae by the reigning ocean currents. in Iceland indude those of Si g U l'd u l' J 6 n s­ The South Icelandic coast is strongly in­ son, who has primarily studied the coloni­ fluenced by the Gulf Stream. This influence zation at the island Surtsey (1966, 1970), those diminishes in the direction north and north­ of Adey (1968) of crustose Corallines and eastwards, and the North Icelandic coastal area finally of the present author. is according to Stefinsson (1962b) influenced My work has been supported by grants from by three primary water masses: Atlantic water, the Icelandic Science Foundation and began in Polar water and Arctic Bottom water. The 1963. Since then, the summers have been spent distribution and mixing of the primary and in investigating the benthic algal vegetation secondary water masses along this part of the at different parts of the Icelandic coast. Icelandic coast has also been thoroughly The purpose of this work is to make as detai­ studied by Stefinsson (1962b). The East Ice­ led review of the benthic algal flora of the Ice­ landic coast is, on the other hand, under the landic coast as possible. Different areas of the influence of the East Icelandic Current, which Icelandic coast were investigated thoroughly is of Artic origin. in each successive year. The changing hydrographic conditions Since the features of the algal zonations in around the Icelandic coast are reflected in a the various parts of the Icelandic coast present most variable composition of the benthic algal such distinct differences, a general preliminary vegetation and in different patterns of the algal review of the most conspicous algal belts, as zonation. found in selected biotopes around Iceland, will Stromfelt (1886b) was first to point out the be given. striking difference between the algal vegeta­ The algal belts, belonging to different tion in the South and vVest Iceland on one littoral levels are given in their vertical sequ­ hand, and that of the East Iceland on the ence in all the profiles, described in this other. paper. Later, Helgi J6nsson (1901, 1903, 1910, Only the dominant species, characteristic for 1912) made a thorough investigations of the the algal zones in the various biotopes will be algal growth around the Icelandic coast. treated here. Some earlier data on the algal vegetation Smaller accompanying species, belonging to around Iceland are found in the works of the undergrowth as well as the epiphytes, will Zoega (1772), Mohr (1786), MilJler be discussed later. (1770), Hooker (1813), Mackenzie (1810), Detailed descriptions of selected regions Hjaltalin (1830), Vahl (1840), Linds­ around Iceland, as observed in succesive years, ay (1861), Kj elhnan (1879), Gronlund will be published separately. (1'879) and Rosenvinge (1879). The material collected is most extensive and Besides, various scientists have made sporadic is still under investigation. Reprensentatives of collections of algae, mainly in the last century, several genera still need a thorough revision, e. g. Ostenfelt (189.5-1896) in connection such as Ceramium) DictyosijJlwn) Enteromor­ with the Ingolf-expedition, Jensen (1890), pha) Cladophora etc. GENERAL FEATURES OF THE llENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 3 ------

o

Dots: Locations of jJrofiles 1 to 7 (Plates 1-7). O/Jen circles: All locations investigated around Iceland between 1963 and 1970.

LITTORAL LEVELS

There are several different opinions regard­ Sernander (1917) defined this limit pri­ ing the definition and delimitation of the marily from a pure physical point of view, thus zones of marine organisms found on the sea by the high water level. The zone above was shores. defined as supralittoral. KyIin (1918) pointed Coastal conditions in places subjected to out that wave action and insolation are in strong tidal influence were treated by early addition to tidal factors decisive for the upp­ Scandinavian authors and apply to the North er limit of the marine vegetation, this so-call­ European coasts. Rosenvinge (1898) defines ed "physiclogical high water line", being the upper limit of the littoral zone as the line inclentical with the "litus-line" defined by were the marine vegetation begins. In Green­ Sjostedt (1908). land, however, this line coincides with the The demarcation between the littoral and lowest high-tide level. The same was true in the supralittoral zone could also be decided by Faeroe Islands, in sheltered locations (Borge­ means of biological entities. sen, 1905). The upper littoral limit was also The lower limit of the littoral zone is less similiarly demarcated by Helgi J6nsson distinct and does not always coincide with the (1912) and Kylin (1907). low-tide level. It is, however, highly dependant ACTA NATURALIA ISLANDICA 21 (1972) on the degree of exposure of the location con­ and northern European regions yield com­ cerned. This limit is a natural physiological parative data of great values, concerning the boundary, influenced by several other factors littoral algal zonation. than the tidal ones. In this connection the works of Borgesen In the present work, the ordinary definition (1904) on the Faeroe Islands, Kj ellman (1906) of the algal zones will be applied, suitable for on Jan :Mayen, Rosenvinge (1893, 1898, the North European areas, thus the division 1910) and Lund (1954, 1959) on Greenland, into a supralittoral, littoral and sublittoral Hygen and Jorde (1934), Levring (1937) zone. Along the Icelandic coast the limits and \'Vennbie;:rg (1950') in West Norway, between the zones are highly dependant on Sundene (1953) in the Oslofjord, Printz the configuration of the substratum and on (1926) in the Trondheimfjord, Kylin (1918) the exposure to wave action and therefore do at the Swedish west coast and Svendsen not exactly follow the low or high water lines. (1959) on Spitzbergen could be mentioned. In order to acquire a better basis for com­ Previous (Foslie, 1890, 1891) and recent parison between the different locations (Jaasund, 1957, 1965) investigations of the surveyed around Iceland, the author divides Arctic area of Norway revealed a likeness the littoral zone proper into an upper, middle with the vegetation features of the Icelandic and lower Ii ttoral. coast. The present investigations are mainly Many authors disagree, however, with the focused on the littoral zone itself. Only the terms sUjJralittoral) littoral and sublittoral. upper boundary of the sublittoral zone was More or less complicated systems have been investigated. established, based on hydrographical zones and Special attention was paid to the tide pool vegetal ones. system occurring throughout the littoral Stephenson and Stephenson (1949) pro­ slopes. posed a widely applicable system in which Differences in both, occurence and sequence, certain littoral levels should be characterised of algal zones in different parts of the Icelandic by the same type of organisms on all shores. coast were studied, as well as local variations Recently L ewis (1964) suggested a modified due to salinity and exposure conditions. terminology, based on biological entities. This Finer variations on a smaller scale are the authors general scheme of zonation reveals result of interaction of different, not yet com­ clearly the differences in the extension of zones pletely known, ecological factors and are in sheltered and exposed habitats and could be difficult to explain at the present state of applicable for the highly exposed locations of knowledge. the rocky shores of Iceland. Descriptions of the vegetation of the western GENERAL FEATURES OF THE BENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 5

PATTERNS OF ALGAL ZONATION AROUND ICELAND

1. Southern Iceland

THE COASTAL AREA BETWEEN species were found in the Fucacean under­ THE RIVERS OLFUsA AND growth of this level. '''There we dealt with sandy slopes in the THJORSA uppermost littoral, a Pelvetia belt was, how­ ever, lacking, the upper littoral growth being represented by EnteramorlJha spp. (E. intesti­ The greater part of this coast line is formed nalis, E. clathrata, E. slJ.), Ulva laetuca, POl'lJ­ by lava rocks, forming support to an about I hyra umbilicalis f. laciniata, B liclingia minima km broad littoral zone which is interrupted by and B. mal'ignata, these species being attach­ a ,,,,hole system of tide pools and lagoons. ed to small stones. This girdle was followed Sandy slopes encountered in the area, downwards either by Fucus slJimlis or directly especially near the Thj6rsa outlet, proved to be by F. vesiculosus. bare for any algal growth. Middle littoral: Extensive fields of Fucus vesi­ A Supralittoral algal growth vvas seldom culosus, mainly represented by f. sphaero­ observed in this area. Along the greater part carpus, and of ASC01Jhyllum noclosu171, cover of the coast line under discussion, the supra­ the lava rocks. On the lower fringe of the littoral level coincides with sandy slopes, but Fucacean fields, Fucus clistichus, subsp. eden­ where we dealt with a faster substratum (e. g. tatus occurs in a relatively narrow zone. area around Gamla Hraun and Stokkseyri) On the Fucus vesiculosus level, the lichen dwarfish Pelvetia canaliculata was found in Verrucaria mucosa as well as H£lclenbmndia company with Rhizoclonium rilJariu/11 in lJ1'OtotYl)US, dwarfish Rhoclymenia palmata, between the grass. Prasiola stilJitata was found B liclingia minima, EnteramorlJha intestinalis together with the lichen Xanthoria l)(ll'ietina and Rhoclochorton splJ. were the main ele­ on rocky formations around Gamla Hraun. ments in the undergrowth. As epiphytes, El­ In the littoral zone proper, the following achista fucicola, EnteramorlJha intestinalis, zonation was the most usual: E. pralifera , EctocarlJus confervoides, Pylai­ Upper littoral: Pelvetia canaliculata was found ella littoralis and SjJongonema tomentosum around the high water mark and a belt of were the nlost common. FUCHS slJiralis lower down the littoral. "Vher" Lower down the littoral, on the ASC01J­ we had to do vvith a rocky substratum in the hyllu171- and Fucus clistichus level, Ralfsia uppermost littoral, a narrow Ulothrix SlJ1J. ­ verrucosa, R. sp., Polysiphonia urceolata, UraslJo')'(l slJP. belt found over Pelvetia, main­ Sphacelaria radicans, Plu17Ull'ia elegans, lVIem­ ly being formed by Ulothrix flacea. A BUclin­ branol)tera alata, Lithothamnion spp., Phy­ giaminima zone could localy overlap with the matolithon SlJ1J., CladolJhora l'upestl'is, Aero­ belts of Pelvetia and of Fucus spiralis. siphonia spp. and Rhodochorton SlJ1J., (main­ In between the belts of the above named two ly R. lJurlJllreum) joined the undergrowth. species of Fucus, tide pools covered by diffe­ Besides Elachista fucicocla, SlJongone171a rent still undefined growth forms of Entera­ tomentosum, EctocacrlJus confervoides, E. sili­ rnorpha intestinalis and E. clathrata as well culosus, Pylaiella littoralis and Entera­ as by ClaclolJhora splJ., were found. morlJha SlJ1J. PoylsijJhonia lanosa proved to Verrucaria mucosa, Hilclenbranclia lJrato­ be the most common epiphyte on Ascophyll­ t'Y1Jl1S, Rhodochorton and EnteromorlJha '//'171,. 6 ACTA NATURALIA ISLANDICA 21 (1972)

Alng the lower boundary of the fucoid halia dentata, Phycodrys rubens, 1HembmnojJ­ vegetaton, Gigartina stellata and Ceramium tem alllta, Ceramium rubnt.m, Chordaria rubnun appeared in the undergrowth. flag-elliformis, Giffordia hinchsiae, PhyllojJ­ Lower littoral: Below the Fucacean vegetation horamembranifolia, DeSI1Ulj-estia ligulata and different algal belts were found, mainly de­ D. virrlis were the most outstanding. pendant on the degTee of exposure. Regarding the lower sublittoral levels, some In moderately exposed places, on gently data could be obtained during the extreme low sloping rocks, Corallina offiGinalis was found tides. Further data are based on the driftweed. together with several accompanying species, e. Huge specimens of Laminm-ia hyjJerborea g. ChaetO'lnorjJha 'melagonium, Ceramium and L. digitata were dominating in the drift­ rubrum, C. areschougii and Dumontia incrass­ weed, together with a number of deep vvater ata. species, the majority being found attached to On semi - exposed sites on islets and cliffs, L. hyjJerborea stipes. In addition to the above as well as in SOlne spots of the mainland, an mentioned species, Desmarestia aculeata, De­ association of Ceramium rubrum - Acrosip­ lesseria sanguinea, Plocamium coccineum, honia spjJ. was found, followed downwards by Euthora cristata, Ptilota plumosa, Pt. pecti­ a pure growth of RhodjJ11wnia palmata. nata, Lomentaria orcadensis and Lomentaria In exposed habitats Gigartina stellata was clatJellosa could be mentioned. forming continuous belts. It was followed by The species Plocamiwn coccineum., Des­ Rhodomela lycojJodioides, Ceramium rubrum, marestia ligulata, Giffordia hinchsiae and C. shuttleworthiamum, C. strictum, C. jJeni­ Lomentaria orcadensis sjJjJ. are, however, limi­ cillatum, Scytosiphon lomentaria, Acrosip­ ted to the south Icelandic coast. honia sjJjJ. and by epiphytic Porphjl1'a abyssi­ Tidal pools: A number of tidal pools was ob­ cola. The floristic composition of the Gigm'­ served throughout the extensive littoral slopes. tina belt was however changing' from place In the upper littoral, at the FuctlS spiralis to place and an impoverishement in the and Pelvetia canaliculata level, tide pools, number of accompanying species was found covered by Enteromorpha and CladojJhora with the increasing surf. Under conditions of species -were most usual. Ulva lactuca in highest exposure this belt is going over to a company with PorjJhym umbilicalis f. laciniata pure Callithamnion arbuscula growth. was found in some pools near Eyrarbakki. The later species was usually found on the On a mid-littoral level Chondrus crisjJUs in its outermost islets and shoals, being characteristic different growth forms, and Ahnfeltia jJlicata for extremely exposed sites of the Atlantic wat­ proved to be dominant species in the tidal er regions of Iceland, up to Hornbjarg. pools. As accompanying species, Rhodymenia Sublittoral: The upper sublittoral fringe is in palmata, Cystoclonium purpureum, Dumontia the south of Iceland most usually covered by a incrassata, Halosaccion j-amentacewn, Ce­ belt of Laminaria digitata f. stenojJhylla. In ramium areschougii, C. circinatum, C. jJeni­ isolated spots, a zone of long and narrow Alaria Gillatum, C. strictum, C. spp., Eetocarpus con­ esculenta was observed though it seems likely fervoides, E. siliculosus, DictyosijJhon foeni­ that the first-named species dominates in ex­ culaceus, Chordaria flagelliformis, Rhodomela posed locations in the south. '!\There the ex­ lycojJodioides, PhyllojJhora membranifolia, posure appeared less severe, Laminaria sace­ CcytosijJhon lomentaria and Ulva rigida were harina f. linearis was replacing L. digitata in most comlnon. a rather prolific growth. In some pools, pure populations of Chondrus As accompanying species in this level, crispus could be found, while Ahnfeltia jJlicata, Rhodymenia palmata, Rhodomela lycojJodioi­ as a rule, was followed by a number of des, Phymatolithon polymorp171lm, Lithot­ epiphytes and accompanying species. hamnion spp., Corallina officinalis, Odont- Lower down the littoral, though still on the GENERAL FEATURES OF THE BENTHIC ALGAL ZO;\lATION AROUND THE ICELANDIC COAST 7

AscojJhyllum.level, smaller rocky pools, covered and Cho1'daria flagellifo1'lnis. As undergrowth, by Corallina officinalis or by Ceramium spp. a dense carpet of Corallina officinalis and (C. rubrum, C. areschougii, C. penicillatum, Lithothamnion spjJ. was usual. Ulva lactuca, C. circinatum, C. shuttleworthianum) were EnteromorjJha lima, E. ahlneriana and Dicty­ most common. ChaetomorjJhalnelagoninum, osijJlwn foeniculaceus were likewise found in Ulva 1'igida, CladojJhom rUjJestris, Entera­ such places. nwrjJha lima and Ectocarpus sjJjJ. could be Isolated cliffs: A particular zonation was ob­ found in the C01'(lllina-pools, served on some smaller cliffs, lying on other­ In splash pools of the lower littoral Chor­ wise bare sandy slopes near the Thj6rsa out­ daria flagellifo1'lnis was rather common. let: Porphyra umbilicalis f, umbilicalis in the Lagoons: Two types of lagoons were observed upper littoral and Fucus distichus ssp. an­ in between the littoral slopes, The coastal cejJs lower down ,the rest of the littoral lagoons, i. e. lagoons near the mainland, were levels coinciding with a sandy ground. usually covered by sand and mud, with turbid water of a relatively high temperature and low salinity. The considerable depth of such la­ REYKJANES PENINSULA goons allows the development of a luxurious Laminaria vegetation represented by The coastal rocks around the peninsula of Lamilwria saccharina in its broad growth form, Reykjanes are rather steep and exposed to Other species found in such lagoons were: strong surf. Due to the relatively narrow Chorda filum, DictyosijJhon foeniculaceus, littoral zone, if compared with the extensive AsjJeracoccus echinatus, EctocarjJUs siliculosus, lava slopes described above, greater variations pcylaiella littoralis, Ulva lactum, EnteromorjJha in the zonation pattern were observed. intestinalis, E. prolifem and E. clathmta. Blidingia minima, B. marginata, Pelvetia Rocky lagoons in the lower and middle canaliculata and Fucus sjJiralis belts were littoral proved to have the same water tempera­ common in the upper littoral levels of the ture and salinity as the surrounding sea. The area, the Ulothrix-Uraspora belts being ab­ algal growth in such lagoons was dominated by sent or poorly developed. Larninaria digitata f. cucculata and L. sacc­ Porphyra urnbilicalis f. umbilicalis could be harina f, linearis. In the shadow of the La­ found in some exposed locations in the upper­ minaria fronds, a prolific growth of Comllina most littoral, and Porphyra abyssicola d. in the officinalis, Rhodymenia jHtlmata, Rhodomela mid-Iittoral. lycojJodioides, Odonthalia dentata, Phycodrys In the mid-littoral, Fucus vesiculosus and rubens, PhyllojJhoramembranifolia, Membran­ Ascophyllum nodosum were found on gently ojJtera alata, Porphyra miniata, Halosaccion sloping rocks, but where the rocks are rather ramentaceum, Lithothamnion sjJjJ., Ahnfeltia steep, Fucus distichus ssp. edentatus or F. d. plicata and ChaetomorjJha melagoninum was ssp. anceps could follow immediately below found. Fucus sjJiralis. Some shallo'"" lagoons connected with the Characteristic for the area was a continuous open sea, were observed in the lower boundary and prolific Cigartina stellata belt (see Fig. 9), of the Ii ttoral zone. A prolific growth of a interrupted by patches of pure Dilsea edulis yellow Rhodcymenia jHtlmata and of Ulva populations, this species being still absent in lactuca was found in such biotopes. the coastal area, described above. In narrow channels between the outer la­ In the Cigartina level, patches of pure goons the water is constantly streaming in growth of Polysiphonia 1l1'ceolata, of Cera­ either direction during low tide. Here a parti­ -mium rubrum, C. strictum, C. shuttleworthia­ cular vegetation was found, dominated by La­ num and C. jJenicillatum and of Rhodomela minaria saccharina f. linearis, Choula filum lycopodioides could ocur. The floristic com- 8 ACTA NATURALlA ISLANDlCA 21 (1972) posItIOn of the Cigartina association showed tuca - Enteml710rpha ahlneriana - Fucus great variations as a response to different de­ distichus ssp. edentatus. grees of exposure, finally going over to a Lower littoral: Ceramium Tllbrum with Cy­ Callithamnion arbuscula association, at maxi­ stoclonium purpuj'eum - Cigartina stellata ­ mal surfheight. Corallina officinalis. In sites, where the slopes are vertical and the Sublittoral: Laminaria digitata f. stenophyUa) exposure rather high, Cigartina is following under conditions of high exposure, or L. sacc­ immediately beneath the barnacle belt, without harina f. linearis) under conditions of mode­ any Fucacean species in between. rate exposure. On gently sloping rocks in the area around The tide pool and lagoon vegetation (see Hafnir the following zonation proved to be the Fig. 13) proved to be similiar as along the coast most usual: line, described at the beginning. Smaller pools, Upper littoral: Blidingia minma - Pelvetia covered by CladojJhora rujJestris) Acmsiphonia canaliculata - Fucus spiralis. sjJp. and AsjJemcoccus echinatus were also ob­ Pools: I) EntemmorjJha intestinalis) 2) E. served. clathrata-Cladophora obUtterata. In the area from Cardskagi and on, a broad Middle littoral: FUCllS vesiculosus - Porphyra FUClIS serratus zone occupied the lower littoral abyssicola - patches of Entemmorpha clath­ slapes. This belt seems to be restricted to a rata) E. flexuosa and Cladophora rUjJestris part of the Icelandis south coast. on the AscojJhyllum nodosum-Ievel, Ulva lac-

II. South West Iceland - Smefellsnes Area

As to the features of algal zonation in South which give support to a rather broad littoral 'tVest Iceland, the Smefellsnes peninsula, limi­ zone, interrupted by tide pools, crevices and ting Faxaf16i from Breidafjordur, appeared to holes. be especially variable and interesting. This Some characteristic profiles will be described. peninsula is obviously some kind of a tlwes­ hold, limiting the distribution of several Longufjihur) an estuarine area with species in either direction as e. g. Pelvetia cana­ sandy ground (cf. Fig. 7): liculata and Chondrus crispus have here their northern limit and the species Polysiphonia nigrescens and Cloiosiphonia capillaris their Supralittoral: bare for any growth. Upper littoral: Entemmorpha intestinalis. southern limit. Middle and Lower littoral: :Mixed belt of: Compared with the south coast, both Pylaiella littoralis) Ectocarpus siliculosus, E. Chondrus crispus and Ahnfeltia plicata were relatively rare while Halosaccion ramentaceum confervoides, Enteml710rpha ahlneriana, E. comressa, Dictyosiphon chordaria, D. foeni­ became more essential for the vegetation patt­ ern, this species having still a subordinate role culaceus and Porphj'j"(1 wnbilicalis f. laciniata. in the south. Sublittoral: Chorda filum and Ulva lactuca. Extensive areas of the south coast of Sncefells­ nes are sandy with basaltic rocky formations in Stahhhamar) basaltic rocky slope) going between, the smooth basalt-rocks forming small over to a sand)) ground) extreme shelter: peninsulas, islets and isolated cliffs. The littoral slopes beneath Sncefellsjokull are, on the other hand, formed of lava. rocks Upper littoral; Blidingia minima and B. mar- GENERAL FEATURES OF THE BENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 9 ginata - EnteromoriJha intestinalis and Pel­ species: Cemmium rubnl1n) C. (l1'eschougii) C. vetia canaliculata - Fucus siJiHllis - Entero­ strictu-m) C. shuttleworthianum) C. peni­ m01'iJha prolifera with E. sp. cillatuln) Cystoclonium iJurpureum) Rhodo­ Middle littoral: Fucus vesiculosus - Porphym mela lycoiJodioides) Petalonia fascia) P. zosteri­ umbilicalis f. laciniata. folia) ScytosiiJhon lomentaria) Dumontia in­ Lower littoral: Ulva lactuca andEnteromorpha crassata) AcrosiiJhonia spiJ.). Or: Callithamn­ linza. ion arbuscula under condition of extreme Sublittoral: Laminaria saccharina (broad surf. form), Chorda filum and Ulva lactuca. Sublittoral: A laria esculenta (narrow form).

Stakkhanwr) basaltic rocky formation ­ Longusker) vertical cliffs) limiting to a moderate slope) midelle elegree of ex­ sanely grounel (see Plate 1): posure: Basaltic blocks, lying isolated on the sandy Upper littoral: Porph)lra umbilicalis f. um­ slopes were frequently observed in the area. bilicalis - Ulothrix [lacca and UrosiJom siJ, ­ A different zonation was found on the exposed Blidingia minima. side of such cliffs, turned towards the open Middle littoral: Fucus distichus ssp. edentatus. sea, and on the sheltered side, turned towards Lower littoral: Acrosiphonia spiJ. with Pylai­ the mainland and limiting to horizontal sandy ella littoralis - a belt of Rhodymenia iJalmata) slopes. On the top of such blocks, PoriJhY'ra Dumontia incmssata) C)lstoclonium iJUr­ umbilicalis f. umbilicalis was found. iJureum) Cemmium siJP,) Halosaccion mmenta­ ceum) Dictyosiphon foeniculaceus - a belt of SHELTERED SIDE: Ulva lactuca with EnteromoriJha linza. Upper littoral: Ulothrix flacca with UrosiJom Under conditions of greater exposure: pencilliformis - Blidingia minima - Fucus Cemmium rubnl1n with Acrosiphonia arcta siJimlis (see Fig. 3). - Rhodomela lycopodioides. Middle littoral: Fucus vesiculosus - PoriJhym Sublittoral: Laminaria digitata f. stenophylla ab)lssicola - Rhodymenia iJalnwta. with A laria esculenta. Lower littoral: bare sandy slopes: - Pools: 1) EnteromoriJha linza-CladoiJhom Longusker) steejJ basaltic rocks) great oblitterata. 2) CladoiJhora rUiJestj'is - Clwe­ exposure: tomoriJhamelagonium.

EXPOSED SIDE: Supralittoral: Prasiola stipitata and P. furfura­ cea - Bangia fuscoiJuriJuj·ea. Upper littoral: Bangia fuscoiJurpurea - Ulot­ Upper littoral: POrph)IH/ umbilicalis f. urnbili­ hrix flacca with Urospom iJenicillifonnis. calis (see Fig. 1) - Ulothri.~ flacca) U. pseudo­ Middle littoral: Fucus distichus ssp. edentatus. flacca and Urospora iJenicilifonnis - Pylaiella Lower littoral: Acrosiphonia arcta - belt of rUiJincola and Petalonia fascia. Ceramium spp. and Pol)lsiphonia urceolata ­ Middle littoral: Fucus distichus ssp. anceiJs ­ belt of Gigartina stellata with Cystoclonium AcrosiiJhonia arcta. iJurpureum) Ceramium rubnlln) C. (/j'esch­ Tidal pools: 1) Comllina otticinalis) 2) Acro­ ougii) C. strictum) Dumontia incmssata and siiJhonia spp. Ulva lactuca - Rhodomela lycopodioides Lower littoral: Gigartina stellata with epip­ with Rhodymenia iJalmata and PolysiiJ­ hytic PoriJhym abyssicola (Accompanying honia nigj'escens - belt of Ulva lactuca. 10 ACTA NATURALIA ISLANDICA 21 (1!172)

Sublittoral: Ala1'ia esculenta (narrow form) rnenia j)(!lmata with Rhodomela lycopodioi­ with Lithothamnion sj)j). and Phymatolithon des and Cystoclonium j)urj)ureum. spp. Tidal pools: 1) Corallina officina.lis 2) Cera­ mium sj)j). Sublittoral: Alaria esculenta (long and narrow H ellnar) lava rock) great exposure) broad form). littoral interrupted by rocky caves) 1)00ls As in the south, the Gigartina zone shows and crevices (see Plate 1): wide variations in its floristic composition around Smefellsnes. Dilsea edulis and Leat­ 'usia diffo1'lnis were joining this association Supralittoral: Prasiola stij)itata - Rhizoclon­ for the first time in the area around Helln- ium rij)a1'ium. ar. Upper littoral: Porj)hyra 11mbilicalis f. umbili­ An impoverishement in the number of calis - Ulothrix flacca with Urosj)ora j)enicilli­ accompanying species with increasing surf was form is - Blidingiaminima with Pelvetia observed also in this area, the Gigartina belt canaliculata - Fucus sj)iralis. gradually going over to a Callithamninon ar­ Tidal pools: Enteromorj)ha intestinalis, 1) 2) buscula belt in highly exposed locations. E. clathrata - E. flexuosa. The outstanding variations in the features Middle littoral: Fucus vesiculosus - Ascop­ of algal zonation of the Smefellsnes peninsula hyllurn nodosurn (undergrowth: Hilden­ are mainly caused by the different substrata in brandia j)rototyjJlIS, Ve1Tucaria mucosa, this area, i. e. sandy slopes, steep basaltic rocks Rhodochorton spp., (R. pllrjJUreum domin­ and extensive lava rocks. ating), Acrosij)honia sp., dwarfish Rhodymenia These differences were obvious in a chang­ I)almata, Cladoj)hora rUj)estris, Plllmaria ele­ ing appearence of the Fucacean belts as well gans) - FucHS distichus ssp. edentatus. as in the lower littoral, where the Gigartina Rocky caves: Phl'lnaria elegans, lVlembmn­ belt could be locally replaced by belts of Cera­ oj)tera alata, Chaetomorj)ha 1nelagonium, mium rubrum-Acrosiphonia sj)., by Ulva lac­ Cladophom rllj)estn's, Chaetopteris j)lllmosa, tllca-Enteromorj)ha linza or by mixed popu­ Sphacela1'ia mdicans, Polysij)honia llrceolata, lations, in which Rhoclymenia j)al1nata, Ceramium areschougii, C. rubrum. Halosaccion 1'amentaceum and Cystoclonium Tidal pools: 1) Halosaccion mmentaceum 2) j)Urj)llreUm were outstanding. Rhodymenia palmata with Ulva lactuca 3) In the upper sublittoral a long and narrow Cladoj)hora rUj)estris 4) Acrosij)honia sj)j). form of A llnia esculenta seemed to replace the Undergrowth of Fucus distichus ssp. eden- Laminaria digitata f. stenophylla belt, en­ tatus: Gigartina stellata, Phymatolithon poly­ countererd in exposed sites of the southern lnorj)hum, Ralfsia vernlcosa, Lithothamnion coast. sj)., Polysij)/70nia urceolata, l11embmnoptera The Ulothrix-Urosj)ora belt proved to be alata, Plu1naria elegans, Ulva rigida. more prominent than along the southern Lower littoral: Acrosiphonia sj)p. (A sonderi, coast. A. arcta) - Halosaccion mmentaceum with In the tidal pools both Chondnls crisjJlIS and Ulva lactuca were found under conditions of Ahnfeltia j)licata were rather rare. The moderate exposure. Under conditions of strong circumpolar species Ha losaccion mmentacewn exposure: Gigartina stellata with Dilsea edulis became, on the other hand, more prominent (see Fig. 2) and Leathesia diffonnis (Accomj)(l­ than in the south, both in the tidal pools and nying species: Cemmium 1'ubntim, C. ares­ on the littoral slopes. chougii, C, circinatwn, C. shuttleworthianum., Clacloj)hora oblitterata in company with C. strictum, Dunwntia incrassata, Scytosip­ Enteromorj)/wlinza proved to bec ommon in sj)., Porphym abyssicola) - belt of Rhody- shallow rocky pools along the southern coast GENERAL l'EATURES OF THE llENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 11 of Sme£ellsnes, while Claelophom ntpestj"is Plry llophora broeliaei were joining while and Chaetol7wj'pha melagonium occupied Plocamium coccineum,) LO'Inentm"ia orcaelens­ sandy pools in the area. is) L. clavellosa) Desmarestia ligulata) Gitt­ Among the sublittoral vegetation Polysip­ orelia hinchsiae and Asperococcus echinatus honia nigreseens) Gloiosiphonia capillaris and seemed to be limited to the southern coast.

III. N orth West Iceland

According to Helgi J6nsson (1910), the Scattered growth 'without distinct zones: coastline between Latrabjarg and Hornbjarg EnteromorjJha intestinalis) Fucus cemnoieles is regarded as the north west part of the Ice­ (see Fig. 8), Fucus vesiculoSllS (estuarine landic coast. In this part of Iceland the algal forms), Dictyosiphon cho1'elaria) EctocarjJUs vegetation of Dyrafjordur was studied in de­ siliculosus) E. sjJ.) E. contervoieles) Entero­ tail. mo1'j)l1(/ prolitera) E. ahlneriana) E. clathrata) In order to be able to draw a comparison E. comjJressa) Ulva lactuca) Pylaiella littoralis. between the zonation in the north west and that, described in the first two chapters, ob­ servations should refer to open coastlines and HValnmur) smaller estuaries along the outermost fjord areas. The growth conditions coast: in the fjord proper are changing from place to place, due to the numerous river outlets and The sea £1001' in such estuaries is formed by varying degTee of exposure. Different features sand and small, voluble stones, to which the of algal zonation were, however, found in the algal growth is attached. inner, middle and outer area of the fjord under Upper littoral: Enteromorpha intestinalis. discussion. Some characteristic profiles will Middle littoral: Scattered growth, without be outlined here. distinct zones, of the following species: Porp­ hyra umbilicalis f. laciniata) l\lonostroma grevillei, III. unclulatum) Ulvaria obscura) DYRAFjORDUR - INNER AREA Ulva lactuca and EnteromorjJha comjJressa. Lower littoral: Bare for algal growth. In the river outlet Botnsa inside Dyrafjord­ ur a fresh water vegetation was still found (Conjugatae) Vaucheria sjJ.) and the transitio­ Sheid) almost horizontal rochy slopes) nal area towards salt water proved to be bare going over to a sandy ground) increased of any growth. salinity: Some profiles of this area will be given in a sequence corresponding to the increasing Upper littoral: Bliclingia mlmma and B. distance from the estuary of the river Botnsa. marginata - EnteromorjJha intestinalis. Middle littoral: FllCUS vesiculosus - Ascop­ Botn) i'nnermost estuarine area (see Plate h'yllum noelosurn (accompanying species: 2): VeJTucaria mucosa) H ilelenbmnclia jJrototypus) EnterOlnorjJha intestinalis) E. prolitem Ecto­ Sandy slopes, corresponding to the upper and carpus contervoicles) - Facus clisticlws ssp. middle littoral level, the entire estuary being evanescens. emerged during low tide: Lower littoral: Belt of filamentous algae: 12 ACTA NATURALIA ISLANDICA 21 (1972)

Dictyosiphon foeniculaceus, D. chordaria, These gradual changes in the composition Chordaria flageUiformis, EnteromorjJha. clat­ of the littoral flora and in the sequence of the Mata, E. ahlneriana, P')Jlaiella littoralis, Eu­ main algal belts could be a function of the desme virescens, ChaetolnorjJha cajJillaris, Ec­ changing salinity and exposure conditions. tocarpus siliculosus, E. confervoides, CladojJ­ hom fmcta. Sublittoral: Chorda filullL DYRAFJORDUR - MIDDLE AREA The mentioned association of filamentous algae could also be found near some local estu­ Ve1'blld - Scdtnes) moderate slojJes (see aries immediately under a belt of Entero­ Plate 2): morpha intestinalis, without any species of Fucaceae in between. Upper littoral: Ulothrix flacw, U. jJseudoflacca and UrosjJora sp. - Fucus sjJiralis. Middle littoral: FllCUS vesiculosus - AscojJ­ Skeid-Thinge)'1'i) moderate rocky slope: hyllum nodosu/n - Fucus disfichus ssp.. ed­ entatllS. Upper littoral: Ulothrix flacca, VrosjJora Tidal pools: 1) Ceramium sjJjJ. - Cystoclo­ penicillifol'lnis - Blidingiaminima - Enter­ nium jJllrjJUreum, 2) Corallina officinalis, 3) omorplw intestinalis - Fucus spiralis with Dictyosiphon foeniclllaceus, 4) Lithothamn­ dwarf Petalonia fascia. ion sjJ.-CladojJhora oblitterata. Middle littoral: Fucus vesiculosus - AscojJhyll­ Lower littoral: Acrosiphonia spp. with Pylai­ um nodosum (Accompanying species: Verru­ ella littoralis - filamentous algae: Chonlaria caria mucosa, H ildenbrandia proto tyjJUs, flagellifonnis, Dict')Josiphon foeniculaceus, Rhodochorton sjJp. (R. jJurjJUreum domin­ EctocarjJus sjJjJ., Elldesme virescens, Entero­ ating), Plumaria elegans, Pol')JsijJhonia urceo­ morjJlw flexuosa - belt of Rhodymenia IJal­ lata) - Fucus distichus ssjJ. evanescens. Inata, Halosaccion ramentacellm and Rhodo­ Tidal pools: 1) Cemmium areschougii - C. mela lycojJodioides. spjJ. - C')Jstoclonium purpw'eum. 2) Cla­ Sublittoral: Laminaria digitata f. cucculata and dophora oblitterata-Lithothamnion spp. L. saccharina f. linearis. Lower littoral: Belt of filamentous algae: Chor­ daria flagellifonnis, DictyosijJlwn foenicul­ accus, D. chordaria, EctocarjJus confervoicics, DYRAFJORDUR - OUTER AREA E. siliculosus, Enteromorpha clathrata, Pylai­ ella littoralis, Ceramium areschougii, C. 'While the algal zonation in the middle fjord rubrum. Belt of Rhod')Jmenia pal/nata-Rho­ area proved to be rather uniform from place to domela lycojJodioides and Ulva lactuca. place, greater variations in the sequence and appearence of the algal zones were again found Sublittoral: Laminaria saccharina f. latifolia and Chorda filum. in the outer fjord regions. As seen from the sequent profiles, the zona­ These variations may be caused by the tion into distinct algal belts gets more out­ gradually increasing exposure and by the changing configuration of the littoral rocks. standing with the increasing distance from Some characteristic profiles vvill be given, the innermost estuary, new belts gradually in a sequence from the inner towards the joining as e. g. the AscojJhyllum nodosum one, outermost locations. that of Fucus sjJimZis and of Ulothrix sjJjJ. ­ Vmspora sjJjJ. The number of species gradually increases Sveinseyri) sheltered location with a further outwards along the fjord coast. moderate slojJe (see Plate 3): GENERAL FEATURES OF THE BENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 13

Upper littoral: Ulothrix flacca - Entero­ Rhodymenia palmata, Rhodomela lycopo­ morpha intestinalis. dioides and Halosaccion 1·amentaceum. Middle littoral: Fucus vesiculosus (under­ Sublittoral: Laminaria digitata f. cucculata, L. growth: Verrucaria mucosa, Hildenbrandia saccharina f. linearis and Alaria esculenta. prototypus, PolcysijJlwnia urceolata, Rhodo­ In the outer fjord area, L. hyjJerborea is chorton jJurpureum, Plumaria elegans, Nlem­ joining the sublittoral growth together with a branoptera alata, Cladophora rupestris, Ralfsia number of deep-water red algae, as e. g. verrucosa, R. fungiformis, dwarfish Rhody­ Odonthalia dentata, Phycod1)'S rubens, Deles­ menia palmata, Lithothamnion sjJjJ., Phyma­ seria sanguinea, Eutlwra cristata, Ptilota sjJjJ., tolithon sjJ. Sphacelaria radicans, S. britann­ RhodojJhyllis dichotoma etc. (see Fig. 12). ica, Chaetopteris jJlumosa) - belt of Fucus distichus ssp. edentatus and F. d. ssjJ. evan­ Lendingar) semi - eXjJosed location with escens (broad zone with still some under­ a moderate slojJe: growth). Tidal pools: 1) Ceramium areschougii, C. circinatum and Cystoclonium jJUrpureum, Upper littoral: PorjJh)l1'a umbilicalis f. um­ 2) Corallina officinalis with Callithamnion bilicalis - Ulothrix flacca with U. pseudo­ hookeri, 3) Ralfsia fungifonnis, Eudesme flacca - Enteromorpha intestinalis and B lid­ virescens and Scytosiphon lomentaria. ingiaminima. Lower littoral: Belt of Rhod)'1nenia palmata, Pools: Enteromo1'pha intestinalis. Rhodomela lycopodioides, Halosaccion ra­ Middle littoral: Ascoph)'llum nodoswn (broad mentaceum, Ulva lactuca and Ceramium zone), accompanying species: Hildenbrandia rubrum. prototyjJUS, Ralfsia fungiformis, R. verrucosa, Sublittoral: Laminaria digitata f. cucculata, L. Plumaria elegans, lvlembranoptera alata, Poly­ saccharina f. linearis and A laria esculenta sijJhonia urceolata, Rhodochorton pw'pureum, (broad form) withLithothamnion spp., Ph),­ R. sjJ., SjJhacelaria radicans, Chaetopteris matol£thon sjJp. and PolysijJlwnia ([1·ctica. plumosa, Spongonema tomentosul11, Cladop­ hom rUjJestris, the last named species being the dominant element in the undergrowth - belt Hdlsar) semz - eXjJosed location with of Fucus distichus ssp. edentatus. steep slojJes: Tidal pools: 1) Corallina otticinalis with epiphytic SjJongonwrjJha aeruginosa, 2) Ceramium sjJjJ. (C. circinatum, C. ares­ Supralittoral: Prasiola stipitata. hougii) and Cystoclonium purpureu1n, 3) Upper littoral: Porphyra umbilicalis f. um­ AcrosijJhonia sjJjJ., 4) Halosaccion ramenta­ bilicalis - Ulothrix flacca with U. pseudo­ ceum, Rhodymenia jJalmata, Ulva 1'igida, 5) flacca and UrosjJora jJenicillifonnis - Fucus Ralfsia fungiform is, Petalonia, fascia, P. spiralis. zosterifolia, ScytosijJhon lomentaria, 6) Pools: 1) Enteromorpha sjJjJ., 2) Fucus Punctaria jJlantaginea, 7) DistyosijJhon distichus ssp. distichus. foeniculaceus with Chordaria flagellifonnis. Middle littoral: Fucus vesiculosus Ascop­ Lower littoral: Chordaria flagellifonnis - belt hyllum nodosum (See Fig. 6) - Fucus distichus of Halosaccion mmentaceum, Rhodymenia pal­ ssp. edentatus. mata and Rhodomela lycojJodioides. Pools: 1) Dictyosiphon foeniculaceus, 2) Sublittoral: Laminaria digitata f. cucculata, L. Acrosiphonia spp., 3) Cemmium sjJp. and saccharina f. linearis, A laria esculenta., Lithot­ Cystocloniwn purjnI1·eum. hamnion spp., Phymatolithon sjJ. (Laminaria Lower littoral: Acrosiphonia sjJp. with Pylai­ h),perborea, Desmarestia aculeata, D. viridis ella littomlis and Ectocarjnls sjJ. - belt of and accompanying deep-water species). 14 ACTA NATl1RALIA ISLANDICA 21 (1972)

Ytri Ofcera) highly eXjJosed site) vertical Supralittoral: PH/siola stipitata and P. fur­ slojJe (see Plate 4): furacea - Rhizoclonium riparium - pools with Enteromorpha intestinalis. Upper littoral: Porl)hyra wnbilicalis f. umbili· Supralittoral: Prasiola stipitata - Rhizoc­ calis - Ulothrix Spl]. with Urospora 051]. loniuln riparium in rocky fissures. Bangia fuscopurpurea - Fucus spiral£s ­ Upper littoral: Porl)hyra umbilicalis f. um­ pools with Enteromorl)ha clathrata. bilicalis - Ulothrix spp. with Urospora lJeni­ Middle littoral: Fucus distichus ssp. anceps cilliformis - Bangia fuscopurpurea. - on relatively sheltered edges: Rhod)'menia Middle littoral: Fucus distichus ssp. anceps palmata with Cladophora rUl]estris. Lower littoral: Gigartina stellata with Leat­ Tidal pools: 1) Ceramium 051)1]., 2) Corallina hesia difformis (accompanying species: Scyto­ officinialis with Callithamnion hooheri, 3) siphon lomentaria, Rhodomela lycopodioides, Acrosiphonia 051)1]., 4) Halosaccion mmenta­ Ceramium rubrum, C. areschougii, C. circi­ ceum - Rhodymenia l)(tlmata, 5) Lithot­ natum, C. strictum., C. shuttleworthianum., hamnion spp. - Cladol)lwm oblittemta, 6) Cystoclonium l)urpureum). Dictyosiphon foeniculaceus - Chordaria Sublittoral: A laria esculenta (narrovl' form). flagellifonnis - Scytosiphon lomentm'ia, 7) Fucus distichus ssp. distichus. In the tidal pools only the dominant ele­ Ofceruvih) highly eXjJosed site) moderate ments were mentioned. slojJe (see Plate 4): Lower littoral: Callithamnion arbuscula. Sublittoral: Alm'ia esculenta (narrow form).

Supralittoral: Prasiola stil)itata - Rhizoclo­ nium ripariunL Considering the characteristic profiles of the Upper littoral: Porphyra umbilicalis f. umbili­ outer area of Dyrafjordur, several differences calis - Ulothrix Spl). with Urosl)ora 051). ­ from the southern and southwestern part of Bangia fuscopurpurea Iceland could be stated concerning the algal Middle littoral: Fucus distichus ssp. anceps zonation. (narrow belt or absent) - Acrosil)honia arcta L

Spercies of Ceramium (C. rubrum., C. aresc­ Fucus vesiculosus and Enteromorpha intesti­ hougii, C. circinatum, C. strictum., C. jJeni­ nalis occur as the first in distinct belts, joined cillatum, C. shuttleworthianum, together with further out the fjord by AscojJh'yllum nodos­ Cystoclonium purjnlreum, were outsanding in um and even longer out by Fucus spiralis and the middle- and lower littoral pools, this F. distichus belts. association differing somewhat from that In the lower littoral, belts of different fila­ encountered in the south, due to the different mentous algae (species of EnteromorjJha, Clad­ accompanying species. ojJhom, Ectocarpus and Dictyosiphon) were As mentioned, Chondrus crispus was ab­ found in the inner fjord regions, whereas out­ sent from the tidal pool vegetation. wards along the fjord, belts of AcrosijJhonia Gigm·tina stellata, still outstanding in the sjJp. - Pylaiella littoralis and of Rhodymenia Im·ver littoral of exposed sites, vvas found in an palmata-Rhodomela lycojJodioides-Halosac­ assciation with Leathesia diffonnis. cion ramentaceUT/1. were usual. Under conditions of less severe exposure, a The sublittoral vegetation was represented belt of Halosaccion Hlmentaceum-Rhodymenia by belts of Chorda filum in the inner fjord palmata-Rhodomela lycojJodioides occupied area, joined further out by a broad form of the lower littoral slopes. Laminaria sacchm·ina. In the tidal pools, Punctaria jJlantaginea, In the middle area, belts of Laminaria digi­ StictyosijJhon tortilis, Dictyosiphon sjJjJ., Pe­ tata f. cucculata-L.saccharina f. linearis-A Zaria talonia spp. and Chordaria flagelliformis esculenta followed the upper sublittoral level, were frequent enough. whereas in the outermost regions the narrow In the fjord proper a non-typical vegetation and long form of A Zaria escuZenta was left. In was found, the floristic composition of the selected spots, however, fields of crustose Cor­ benthic vegetation and the sequence of the allines were solely found in this level. algal belts changing from place to place, as a Laminaria hyjJerborea, with its accomp­ response to salinity variations and different anying species, joins the sublittoral vegetation configurations of the substrata. for the first time in the outer fjord area. In the innermost, estuarine fjord area the A marked increase in the number of species algal vegetation still appears in a scattered was found from the inner towards the outer growth and distinct belts are formed firstly in fjord regions. a certain distance from the river outlet.

IV. North Iceland

The north part of the Icelandic coast, from As had already been established, before the Hornbjarg to Melrakkasletta, revealed notable turn of the century, the Irminger Current variations in the benthic algal zonation of ex­ divides into a westerly and a easterly branch posed sites, since Hornbjarg still shows off North "Vest Iceland, the easterly branch Atlantic features, similiar to those encountered flowing clockwise along the north coast. in the north west, whereas Melrakkasletta re­ Hydrographic investigations have revealed that presents a transitional area leaning towards the there are great fluctuations in this influx, both Arctic conditions in the east. seasonal and annual (S t~Hnsson, 1954b, The amount of the Atlantic water reaching 1962b). the north coast probably has a marked in­ The northward extension of the Atlantic fluence on the occurrence and distribution of water should be maximal in the middle of the the Ii ttoral algal species. North Icelandic coastal area or in regions 16 ACTA NATURALIA ISLANDICA 21 (1972) ------~ ------where the Icelandic submarine terrace is The following zonation was found: broadest. In the Grimsey basin, an anticlock­ Upper littoral: Ulothrix flacca - Blidingia wise flow of the current was suggested. minima - Enteromorpha intestinalis - Fucus Further to the east the Irminger Current spiralis. bends to the southeast joining the East Ice­ Middle littoral: Fucus vesiculosus - Ascop­ landic Current north of Melrakkasletta hyllllm nodosum - Fucus distichliS ssp. evan­ (Stefansson,1962b). escens. The algal vegetation of the Hunafl6i bay was Lower littoral: Belt of filamentous algae: investigated, both in Steingrimsfjordur and DictyosijJhon foeniculaceus, D. chordaria along the open eastern coast around Skaga­ Ectocarpus silicuosus, E. confervoides, P)Jlai­ strond. Outstanding differences from the algal ella littoralis, Eudesme virescens, Chaeto­ belts found in the northwest were observed, morjJha cajJillaris, EnteromorjJha prolifera, E. the eastern side of the Hunafl6i bay having a ahlneriana, E. clathrata, CladojJ!wra flexuosa. more distinct Atlantic character than Stein­ Sublittoral: Chorda filum. grimsfjordur. This applies to the general features of the algal zonation as well as to the occurence of particular species. STEINGRIMSFjORDUR ­ This difference may be caused by differ­ ences in the distribution of the drift ice in the MIDDLE AREA Hunafl6i bay. Only the algal vegetation of Steingrimsfjord­ Brekkutlln) steep rocky slopes in the ur will be outlined here as well as that of the upper littoral and Jrwderate slojJes on the island Grimsey in Eyjafjardarsysla, while the lower levels: eastern part of Hunafl6i and the transitional area of Melrakkasletta will be treated in a Upper littoral: Ulothrix flacca, Urospora separate paper. jJenicilliformis - Bangia fuscopurpllrea Blidingia minima - Rhodochorton sjJp. ­ Fucus sjJiralis. STEINGRIMSFjORDUR - INNER Middle littoral: Fucus vesiculosus - Ascop­ h)Jllum nodosum - Fucus distichus ssp. eden­ AREA tatus. Tidal pools: 1) Ceramium ru.brum, C. In the innermost estuarine area of Stein­ strictum, 2) Enteromorpha spjJ., 3) Dictyo­ grimsfjordur similiar growth conditions and a siphon foeniculaceus with Chordaria flag­ similiar vegetation was found as in the inner elliformis, 4) StictyosijJhon tortilis. part of Dyrafjordur. Lower littoral: AcrosijJhonia spp. with Pylai­ ella littoralis - Rhodymenia palmata, Rhodo­ Stadard river outlet innermost estuary: mela lycopodioides and Halosaccion ramen­ taceum - belt of Chonlaria flagellifonnis. No distinct zones were observed, FUCHS Sublittoral: Chorda filum - Laminaria sacc­ ceranoides, F. vesiculosus, Dictyosiphon chor­ harina f. latifolia. daria, EnteromorjJha intestinalis, E. prolifera, E. ahlneriana, Ulva lactuca, Clado:!J!wra fracta, Pylaiella littoralis and Eetocarplls sjJp. STEINGRIMSFjGRDUR occurring still in a scattered growth. OUTER AREA

Thingstadur) further out the inner fjord In the outer fjord regions, for the first time, area: outstanding differences from the algal zona- GENERAL FEATURES OF THE BENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 17 tion as encountered along the north west Petalonia fascia-Eudesme virescens, 5) Clad­ part of Iceland were observed. These differ­ ophom oblitterata-Lithothamnion spp. ences refer above all to the lower Ii ttoral levels Lower littoral: AC1'OsijJhonia spp. - Cemmium of exposed sites. 1'ubmm - Petalonia fascia and Scytosiphon Halosaccion mmentaceum is here the lomenta1'ia - Halosaccion mmentacewn with dominant element of the lower littoral, replac­ 1\1Y1'iactula lubrica - belt of Chorda1'ia flag­ ing as such the Gigartina- and Callithamnion ellifonnis. arbuscula belts, encountered in the south, Tidal pools: 1) Corallina officinalis, 2) Cera­ southwest and northwest (see Fig. 10 and 11). mium sjJp., 3) AC1'osiphonia spp. A further characteristic feature was a Chor­ Sublittoral: Lamina1'ia digitata, L. saccha1'ina f. daria flagellifonnis belt, occuring in some loca­ linea1'is, Ala1'ia esculenta tions lower than Halosaccion. Corallina offi­ cinalis gets a subordinate role in the vegeta­ Highly exposed location with a moderate tion pattern, being mainly limited to the tidal pools. slope (see Plate 5): Further differences from the northwestern vegetation refer to the Fucacean undergrowth, Upper littoral: Ulothrix spp. - Urospom peni­ where Plumaria elegans and lVlembranoptera cillifonnis - Bangia fuscopurpu1'ea - PorjJ­ a.lata are lacking. hym umbilicalis f. umbilicalis - Rhodocho1'­ The Ulothrix-UrosjJora belts became even ton sp. and Pylaiella 1'ujJincola - FUCHS SPi1'­ more outstanding and Acrosiphonia belts were aliso locally found in the outer fjord area. Tidal pools: 1) Ente1'omorpha intestinalis, 2) Observations revealed, however, that Horn­ Fucus distichHS ssp. distichus, 3) Stictyo­ bjarg most likely represents rather sharp siphon t01'tilis. limits, regarding both the distribution of Middle littoral: FUCHS vesiculosus - Fucus single species and the general pattern of the distichus ssp. edentatus. algal zonation. Lower littoral: Acrosiphonia spp. - belt of Cemmium rub1'1l1n, C. shuttlewo1'thianum Moderatly eXjJosed location with a mode­ and C. a1'eschougii - belt of Halosaccion mmentaceum-C:vstocloniU'm purpu1'eum (or H. rate slope: l' .- Rhodymenia jJalmata - Rhodomela leyco­ jJodioides) - belt of Chorda1'ia flagellifonnis. Upper littoral: Porphyra umbilicalis E. umbili­ Pools: 1) Comllina officinalis, 2) Cemmium calis - Ulothrix flacca with U. pseudoflacca sjJp., 3) Acrosiphonia spp., 4) Ralfsia fungi and Urospora sp. - Blidingiaminima with fonnis. B. marginata and B. chadefaudii - Entero­ Sublittoral: Alm'ia esculenta (narrow form). morpha intestinalis - FuCHS spimlis. Middle littoral: FUCHS vesiculosus - AscojJ­ hyllum nodosum (undergrowth: Hilden­ bmndia prototypus, Rhodochorton spp., Ve1Tll­ GRIMSEY IN EYJAFJARDARSYSLA caria mucosa, Ralfsia verrucosa, Lithotham­ nion spp., poleysijJhonia urceolata, Cladophom The coasts of the island Grimsey, situated 1'upestris, dwarfish Rhodymenia palmata, on the Polar circle, are exposed to the strongest SjJhacelaria mdicans, S. britannica, Chaetop­ surf. teris plumosa) - belt of FuClls distichus ssp. The algal vegetation still bears Atlantic edentatus. features, though differing from the vegetation Tidal pools: 1) Dictyosiphon sjJp., 2) Punc­ pattern of the rnainland. taria plantaginea, 3) Stictyosiphon tortilis, 4) Some typical profiles will be outlined. 18 ACTA NATURALIA ISLANDICA 21 (1972) ------~------

Steep and exposed rock)) formations: Pools: Enteromorpha intestinalis and E. clathrata. Supralittoral: Prasiola stipitata with P. fU1'­ furacea (about 5m broad belt) - Rhizoclo­ Sheltered sides of rocky walls: nium ripm'ium - Ulothrix spp. Upper littoral: Ulothrix spjJ. with Urospora Upper littoral: Ulothrix spp. - Rhodochorton penicillifo1'lnis (broad zone) - Porphyra um­ sp .- Porphyra umbilicalis f. umbilicalis, bilicalis f. umbilicalis. Fucus spiralis. Pools: Enteromorpha intestinalis, E. clat­ Middle littoral: Fucus vesiculosus - FUC1is hnltn, and Cladophora sp. distichus ssp. edentatus - Scytosiphon lomen­ Middle littoral: Fucus distichus ssp. anceps. taria, belt of Petalonia fascia P. zosteri­ Lower littoral: Halosaccion ramentaceum with folia. Rhodymenia jJalmata and Rhodomela lyco­ Pools: 1) Acrosiphonia sjJp., 2) Ceramium podioides - belt of Chordaria flagellifo1'lnis. rubrum and C. strictum., 3) Chordaria Sublittoral: A laria esculenta and Laminaria flagellifo1'lnis - DictyosijJhon spjJ. digitata. Lower littoral: Acrosiphonia spp. - Halosac­ Huge amounts of driftweed indicate a cion 1'alnentaceum and Ulva lactuca fields. luxurious growth of Laminaria hype1'borea on Pools: 1) Corallina officinalis, 2) Ralfsia the lower sublittoral slopes. fungiform is. Rocky caves: Chaetomo1'pha melagonium, Inlets with a moderate slope) li1nited by Polj1sijJlwnia urceolata, Antitluunnion floc­ cosum, A. sp., Chaetopteris jJlumosa, Spha­ vertical rock)) walls: celaria radicans. Sublittoral: A laria esculenta, Laminaria Supralittoral and upper littoral: Ulothrix spp. digitata and L. sacchal'ina. - Rhodochorton sjJp. (broad zones, covering the vertical slopes) - Porphyra umbilicalis f. umbilicalis and Fucus sjJiralis belts (on mode­ Exposed side of rocky walls: rate slopes). Middle littoral: (with moderate rocky slopes): Upper littoral: Bangia fuscopurpurea Fucus distichus ssp. edentatus - Scytosiphon Ulothrix sjJp. with UrosjJora penicilliformis lomentaria, Petalonia fascia and P. zosterifolia (these two belts extending into the supra­ belt. littoral levels) - Porphyra umbilicalis f. um­ Lower littoral: Acrosiphonia spp. - belt of bilicalis (occupying horizontal surfaces in the Halosaccion ramentaceum, Ulva lactuca, rocks and occurring thus above or below the Rhodymenia palmata and Rhodomela lycopo­ Ulothrix and Bangia zones). dioides - Chordaria flagellifo1'lnis (narrow Middle littoral: Dwarf Petalonia fascia and belt). P. zosterifolia - dwarf Fucus distichus ssp. Sublittoral: A laria esculenta (narrow form). ancejJs (1-3cm). Steep basaltic formations were encountered Lower littoral: nwarf Rhodymenia palmata at Grimsey, with algal zones developed on and Halosaccion ramentaceum-belt of Chor­ either side. A difference in the sequence of daria flagellifonnis. algal zones was found between the relatively Sublittoral: A laria esculenta (narrow form). sheltered and the exposed sides of such rocky Due to the strong surf, the algal vegetation walls (see Plate 5). of Grimsey exhibits particular features, differ­ Supralittoral on rocky walls: Prasiola stipitata ring from those on the mainland. - P. fw'!uracea. zones were found on both Extensive Prasiola stijJitata belts occupy the sides and Rhizoclonium riparium. supralittoral slopes. The outstanding Ulothrix GENERAL FEATURES OF THE BENTHIC ALGAL ZO~ATION AROUND THE ICELANDIC COAST ------~-~-----~------19

- Umsi)ora and Bangia belts could locally cular zonation of dwarfish specimens of Peta­ reach into the levels of the spray zone. lonia Spi).) Fucus distichus ssp. anceps and On vertical walls, limiting small inlets, con­ Rhodymenia i)almata was observed, such an spicous Rhoclochorton Spi). belts were deve­ extreme reduction of specimens not being loped under the Ulothrix zone. found any other place around the Icelandic A belt of Petalonia fascia-P. zosterifolia coast. proved to be characteristic for the middle Due to the high exposure, the Fucacean littoral, whereas in the lower littoral Acmsip­ growth is poorly developed on this island. honia fields were found on moderate slopes, The tidal pool vegetation of the area still and lower down meadows of Halosaccion proved to bear typical Atlantic features, with ramentaaceum-Ulva lactuca. both Corallina officinalis and several Cera­ In sites, exposed to strongest surf, a parti- mium species being represented.

V. East Iceland

The existence of an East Icelandic Current The influence of the Arctic waters on the of Arctic origin had been postulated already benthic algal vegetation seems to be the before the turn of the century. strongest in the mid east. This current, having its origin in the Scores­ The general features of the algal zonation of by Sound, has a strong flow over the submarine East Iceland will be outlined on the example terrace in the northeast and turns north of of Reydarfjordur, which has been investigated j\!Ielrakkasletta towards the east (S teHnsson, in detail, while the vegetation of the transi­ 1962b). tional areas will be treated in separate papers. In the region north of Gerpir, a rather sharp boundary between Atlantic and Arctic waters was found by the same author. Here, the North REYDARFJORDUR - INNER Icelandic Irminger Current, being cooled and AREA diluted during its passage over the insulary shelf, leaves the coastal area. In the innermost, estuarine part of the fjord, South of Papey, approximately on the line around Budareyri, a scattered growth was between Eystrahorn and Vestrahorn, there is found on the sandy slopes, totaly emerged again a well defined boundary between during low tide. The main species represented Atlantic and Arctic waters. were: Fucus ceranoides) estuarine forms of These lines of demarcation are subjected to F. vesiculosus) Dictyosiphon chonlaria) Pylai­ both seasonal and annual translocations. ella littoralis) Ulva laduca) Enteromorpha The algal vegation of the East Icelandic intestinalis) E. pmlifera) E. ahlneriana) Ecto­ coastal area was investigated in several places, carpus spp.) Monostroma grevillei) Ulvaria in order to get an idea about the gradients obscura) Porphyra umbilicalis f. laciniata. in the vegetation patterns as created by the In Dyrafjordur, Porphym - Monostmma changing hydrographic conclitions. appeared as a separate association in local The changing vegetation features were ob­ estuaries, 'whereas they seem to overlap with served on the line Melrakkasletta - Langanes the rest of the estuarine growth in Reydar­ - Vopnafjordur - Mj6ifjordur - Reydarfjord­ fjordur. ur - StOdvarfjordur - Berufjordur - Alfta­ In a certain distance from the river outlet fjordur - Hvalnes - L6nsfjordur - Horna­ the algal belts became distinct, due to the faster fjordur - HrolIaugseyjar. substratum and increased salinity. 20 ACTA NATURALIA ISLANDICA 21 (1972)

Kro/mr: Upper littoral: Ulothrix flacca-U. sp. - Blid­ ingia minima - Enteromorj)ha intestinalis ­ Upper littoral: Bliclingia minima Entero- FUCHS sj)imlis. morpha intestinalis. Tidal pools: Fucus distichus ssp. distichus. Middle littoral: FUCHS vesiculosus - Fucus Middle littoral: Ascoph)1llwn nodos1lm ­ clistichus ssp. evanescens. Acrosiphonia sj)p. Lower littoral: Belt of filamentous algae: Lower littoral: Acrosij)honia spp. with Pylai­ Pylaiella littomlis, Ectocm'p1ls silic1llos1ls, ella littoralis - belt of Halosaccion mmenta­ Dictyosij)hon foeniculaceHs, D. chorclaria, ceum) Rhodymenia palmata and Rhodomela Chaetomorj)ha caj)illaris, Enteromorpha clat­ lycoj)oclioides - belt of Chordaria flagelli­ hrata, E. ahlneriana, E. prolifem, Cladop­ formis and Scytosij)hon lomentaria. hora fracta. Tidal pools: 1) Acrosiphonia spp., 2) FUCHS Sublittoral: Chorda filum. distichus ssp. distichus, 3) Porj)hym mini­ ata - Lithothamnion sj)j). - Lej)toj)hytum sj). REYDARFJORDUR - MIDDLE Lagoons: Laminaria digitata f. cucculata ­ Saccorhiza dennatodea. AREA Sublittoral: A laria esculenta (broad form). Grima) modemte slojJe: REYDARFJORDUR - OUTER Upper littoral: Ulothrix spp. - Urosj)ora sp. - Enteromorj)ha intestinalis - Porj)hym 1l1n­ AREA bilicalis f. laciniata - Fucus sj)imlis. Firstly in the outer area zonation features, Middle littoral: Fucus vesiculosus - Ascop­ characteristic for East Iceland, became visible. hyllum nodosum (accompanying species: Some of the most characteristic profiles will H ildenbrandia j)rototypus, Polysij)honia be outlined here (see Plate 6 and 7). urceolata, Chaetoj)teris j)lumosa, Sphacelm'ia mdicans, Sj)ongonema tomentosum, Ralfsia sj)j)., Acrosiphonia sj)') - F1lCUS distichus Kolm'zlli) moderate exposure-gently ssp. evanescens. Tidal pools: 1) Porj)hyra miniata, 2) Nlono­ slojJing rocks: stroma spj). Lower littoral: Belt of filamentous algae: Supralittoral: Prasiola stipitata - Rhizoc­ Dictyosiphon foeniculaceus, Chordaria flag­ lonium rij)(l1'ium. elliformis, Eudesme virescens, Petalonia fascia, Upper littoral: Porj)hyra umbilicalis f. 21m· Ectocarj)us siliculosus, E. confervoides, Chaeto­ bilicalis - Ulothrix sj)j). - Urosj)om sj)j). morj)ha caj)illaris, Enteromorj)ha clathrata, E. (broad belts) and accompanying species: Scy­ ahlneriana, Cladoj)hom flexuosa - belt of tosiphon j)ygmaeus, dwarfy Pylaiella rupin­ Rhodymenia j)(tlmata, Ulva lactuca and Halo­ cola - belt of Blidingia minima and B. saccion ramentaceum. chadefauclii - Fucus sj)imlis. Sublittoral: Laminaria saccharina, L. digitata A conspicuous belt of Cyanoj)hycean species, and single Chorda filum. containing mainly Calothrix crustacea, C. scojntlorum and Schizothrix calcicola is over­ Grima) steejJ rocky slojJe: lapping ,vith the POrph)1Hl umbilicalis - and P)1laiella Tllpincola-zones. Supralittoral: Prasiola stipitata - Rhizoc­ This CyanOph)1Cean zone seems to be out­ lonium ~·ij)arium. standing for the upper littoral levels of the GE"'El~AL FEATURES OF THE BENTHIC ALGAL ZO:'-lATION AROUND THE rSELANDIC COAST 21

North Icelandic coastal area and has like­ surf may prevent the attachment of Fucacean wise been found in the east. species, the middle littoral level being covered Middle littoral: Ascophyllwn nodosum ­ by AcrosiiJhonia siJP. fields where the slopes Fucus distchus ssp. edentatus - AcrosiiJhonia are maderateo siJP. (A. sonderi, A. arcta, A. siJ.) meadows. Lower littoral: ScytosiiJ1wn lomentaria - belt Vattarnes) high exjJosure - vertical slojJe: of Halosaccion mmentaceum, Rhodymenia palmata and Rhodomela l'ycOiJodioides - belt of Ulva lactuca - Chordaria flagellifonnis Upper littoral: PoriJhyra umbilicalis f. um­ with Chorda tomentosa. bilicalis -Bangia fusCOiJw'purea - Ulothrix Sublittoral: A laria esculenta, Laminm-ia SiJiJ. with UrosiJom siJ. and U. iJenicilliformis digitata and Saccorhiza dermatodea (drift­ pools with EnteromoriJha spiJ. (different weed from the lower sublittoral: Alaria escu­ growth forms ot E. intestinalis and E. clat­ lenta, Laminewia hYiJerborea, Ptilota species, hrata). Euthora cristata, Rhodophyllis dichotoma, Middle littoral: Fucus distichus ssp. anceiJs, PolysiiJlwnia arctica, PoriJhyra miniata, Antit­ Rhodochorton iyurpureum and dwarfy Aero­ hamnion boreale, Tunnerella iJennyi, Des­ siiJhonia SiJiJ· marestia aculeata, D. viridis, Peyssonelia Lower littoral: PariJhyra linearis (broad zone) rosenvingii etc). - Halosaccion ramentaceum, Rhodymenia pal­ mata and Rhodome.la lycOiJodioides - belt of Chordaria flagellifonnis and Chorda tomen­ Vattarnesb6t, high exposure - moderate tosa. slojJes: Sublittoral: A laria esculenta (narrow form).

Supralittoral: Pmsiola stipitata. Vattarnes-HafnaT1~es) Upper littoral: PoriJhyra umbilicalis f. um­ bilicalis Ulothrix SiJiJ. with UrosiJora sp. extreme eXjJosure - vertical slopes (see and U. iJenicillifonnis (broad zone) - Rhodo­ Fig. 15): chorton siJ. and Pylaiella rUiJincola - B lidin­ gia minima with B. duulefaudii - AcrosiiJ­ Upper and middle littoral: Broad belt of honia siJ. Ulothrix siJP., Urospom sp. and U. penicilli­ Middle littoral: Fucus disticlws ssp. anceiJs ­ fonnis. fields of Acrosiphonia SiJiJ. Lower littoral: Porph)i1'a linearis - Chordaria Tidal pools: 1) Acrosiphonia spp., 2) Fucus tlagellifonnis. distichus ssp. distichus, 3) Clathromorphum Sublittoral: Alaria esculenta (narrow form), a circumscriiJturn - LeiJtoiJhytwn laeve ­ part of the Chordaria zone reaching into the Porphyraminiata, 4) Ralfsia fungifonnis ­ sublittoral. Coilodesme bulligera, 5) StictyosiiJhon tor­ Porphyra linearis- and Chordm'ia flagelliformis tilis) 6) Dict)losiphon foeniculaceus - D. zones, found in steep and highly exposed sites, corymboslls - Chordaria flagellifonnis, 7) seem to replace the Gigm·tina- and Callit­ Petalonia siJP. - ScytosijJlwn lomentaria. hamnion arbuscula belts, encountered in Lower littoral: AcrosiiJhonia siJP. 'with Entero­ similiar biotops in the Atlantic water regions moriJ1w groenlandica Halosaccion ra­ up to Hornbjarg, as well as the Halosaccion mentaceum f. robustum (or Porphyra linem'is) belt, characteristic for the north coast. - Chordaria flagellifarmis with Chorda tomen­ An outstanding Ulothrix siJP.-Urospora SiJiJ. tosa. belt and extensive AcrosiiJhonia SiJiJ. fields Sublittoral: Alaria esculenta (narrow form). 'were further characteristic features of the algal \t\Tith the increasing exposure, the strong zonation in East Iceland. 22 ACTA NATURALIA 1SLANDlCA 21 (1972)

Due to the absence of several cold Boreal exposure and configuration of the coastal species, such as Corallina officinalis, Ceramium rocks. In the outer fjord regions, FUC1ls disti­ spjJ., Cystoclonium jnlrjJllreum, Gigartina chus ssp. edentatus and F. d. ssp. ancejJs were stellata and others, the vegetation pattern of dominating. the tidal pools appeared different. The floristic composition of the Ascop­ Tidal pools, covered by different growth hyllum zone exhibited likewise certain differ­ forms of Fucus distichus ssp. distichus and by ences, due to the absence of some species in the different filamentous brown algae (Dictyo­ undergrowth and the common epiphyte siphon spp., Choularia flagelliformis, Stictyo­ PolysijJhonia lanosa. siphon tortilis), were the most common, beside In the sublittoral, Saccorhiza de1'lnatodea such covered by Acrosiphonia spp. and by was found together with A laria esculenta and ClatromorjJhum cil'cumscrijJtum, LejJtojJ­ Laminaria species in sheltered sites, whereas lYytum sjJ., Porphyra miniata, Coilodesme under conditions of high exposure only the bulligera and Ralfsia fungiormis. belt of narrow and long Alaria esculenta was The Fucacean zonation was changing from left (see Fig. 14). place to place, due to the varying degrees of

DISCUSSION

The general features of the algal zonation, strictum, C. jJenicilliatum, C. spp., Cystoc­ as encountered in different parts of the Ice­ lonium jJurjJllreum, Rhodomela l)JcojJodioi­ landic coastal area, show conspicous variations. des, Acrosiphonia sjJp., Dumontia incrassata, ScytosijJhon lO1nentaria etc. Around Reykjanes and Smefellsnes, Dilsea edulis is joining this Regional variations. belt. \'Vith increasing exposure, an impoverish­ ment regarding the number of accompanying Differences between the vegetation patterns species was found, pure Gigartina populations of selected areas are most visible in exposed being left under conditions of strong surf. and open locations, which are in direct con­ In extremely exposed sites, Gigartina stell­ tact with the oceanic waters. ata was replaced by Callithamnion arbuscula Ii Algal belts, occurring in the lower t toral belts, but where the exposure is moderate zone, thus on a level between the Fucacean Ceramiuln rubnlm-AcrosijJhonia spp. belts and the Laminarian species, show the most were found on the same level. outstanding differences between coastal areas A further characteristic feature were Cor­ where different hydrographic conditions are allina officinalis beds, occurring on gently reigning. sloping rocks lower than Gigartina. Almost pure Atlantic waters surround the The dominant tidal pool inhabitants of south and south west of Iceland, where also the southern coast were Ceramium spp., Cor­ the annual temperature variations are mini­ allina offic£nalis, Chondnls crispus, Ahnfeltia mal. plicata and Aspe1'OcoccuS echinatus. In the south, a Gigartina stellata belt was Around the Smefellsnes peninsula, the Gi­ characteristic for highly exposed locations. gartina zone proved to be extremely prolific Several species were found in between this and joined by Leathesia diffo1'lnis, beside the belt, such as Ceramium rubnlm, C. penicilla­ accompanying species, named above. tum, C. areshougii, C. shuttleworthianum, C. Both Chondnls crispus and Ahnfeltia GENERAL FEATURES OF THE BENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 23 ~~~~~- plicata proved to be more rare in the tidal Along the North Icelandic coastal area, both pools, while Asperococcus echinatus disap­ Gigartina stellata and Comllina officinalis peared from the vegetation. have a subordinate role in the vegetation Along exposed coast lines of the north­ pattern and Hornbjarg represents a further western peninsula, Gigartina stellata-Leathesia limit for the northeastwards distribution of difformis or Callithamnion Qj'buscula belts several species, such as Callithamnion arbu­ were still observed up to Hornbjarg. scula, Plumaria elegans, JHembranoiJtera alata In this area, Comllina officinalis is forming and others. extensive meadows in the lower littoral and Hydrographic conditions along this part of upper sublittoral, and is as well dominating the Icelandic coast have been thoroughly in the tidal pools. investigated by Stefinsson (1962b). Since both the Smefellsnes peninsula and As mentioned, the Irminger Current, con­ Litrabjarg represent thresholds, limiting the veying Atlantic water along the western coast distribution of several species, the vegetation of Iceland, divides into a westerly and easterly of the northwestern part of Iceland shows some branch in the northwest. The east flowing differences from that found in the south and Irminger Current appears as a moderately southwest. The absence of Chondrus crispus strong current near the slope of the coastal in the tidal pools and of Dilsea edulis and Du­ shelf in the north, while near the shore the montia incrassata in the Gigartina zone is current appears week and irregular. This notworthy. current leaves the coastal area north of Gerpir Temperature variations in this area are in the east (Stefinsson 1962b). greater, being dependant on the heating effect Considerable temperature variations, found of the Atlantic water (the amount of its influx in this area, are however caused by the vary­ varying both seasonally and annually) on ing influx of Atlantic water which diminishes climatic factors and on the distribution of drift in the direction west to east as well as by the Ice. changing extension of drift ice and climatic Since changes in the zonation pattern of factors. Changes in the extension of the East exposed locations between the south, south­ Icelandic Current and East Greenland Current west and northwest were not abrupt, but are further decisive for the temperature con­ rather conspicous, a rather sharp threshold was ditions along the north Icelandic coastal area. found at Hornbjarg. The transitional areas in the northeast, thus The algal vegetation of the surroundings of the coast line between Melrakkasletta and Hornbjarg still bears a likeness with the one Langanes, revealed a gradual change in the observed in the northwest, while great changes vegetation pattern. were found in the Hll11afl6i bay. In the mid-east, PoriJ!vyra linearis and Chor­ In the outer reginos of Steingrimsfjordur, daria flagellifonnis zones were outstanding in Halosaccion mmentaceum is replacing the steep, exposed locations, whereas on gently Gigartina zone. This outstanding Halosaccion sloping rocks extensive Acrosiphonia spp. belt is following the entire north coast, up to meadows were found. the mid-east. Rhodymenia iJalmata, Rhodo­ Along the East Icelandic coast, the East mela lycopodioides, Cystoclonium purpurewn Icelandic Current, which is of Arctic origin, and Ulva lactuca could appear as the main greatly influences the vegetation pattern. Most accompanying species in this belt. of the cold- and warm Boreal species are Jaasund (1965) found a similiar difference absent along the coast line between Vopna­ in the vegetation pattern in the Arctic part of fjordur and Hrollaugseyjar (e. g. Comllina the Norwegian coast, Gigartina belts in Troms officinalis, Cemmium spp., Cystoclonium being replaced by Halosaccion belts in Finn­ iJll1'iJureum, Gigartina stellata and many oth­ mark. ers. 24 ACTA NATURALIA ISLANDICA 21 (1972)

The outstanding differences between the the benthic algal vegetation, than the rest of algal vegetation of the east coast and the other the ecological factors involved. parts of Iceland have already been emphazied Adey (1966, 1968), studying the distribu­ by earlier authors (Helgi J6nsson, 1910, tion of crustose Corallines around Iceland 1912; Stromfelt, 1886b}. and in the northern Atlantic as a whole, Regional changes in the appearence of algal admits that high and low temperatures control belts were less expressed in the middle and the distribution of Comllines around Iceland, upper littoral levels. Regarding the upper­ with minimum winter temperatures as limiting most littoral zone, an increase of the extension factor. of the Ulothrix-Urospom belts was found in The crustose Corallines) limited to deep the northern and northeastern direction. This water layers, should according to Adey, reflect zone is still fragmentary or absent in the south a 10 years water climate which is however more and gets gradually broader and more expressed stable in the depth than in the surface layers. towards the northwest and north, being the The littoral algal vegetation is, on the other most outstanding in the mid-east. hand, submitted to great annual and seasonal Pelvetia canaliculata) occupying uppermost variations, taking place in the upper water littoral slopes in extreme shelter, was found up layers. Conditions in these layers are also to the Smefellsnes peninsula. dependant on the duration of rain periods, The Fucacean belts, occupying middle wind directions, ice conditions, thus a com­ littoral slopes, showed rather changing sequ­ plex of factors which may, however, influence ences as a response to varying degress of expo­ the appearence of annual species. sure, configuration of the coastal slopes and In order to be able to make more reliable tidal ranges in selected areas. The main differ­ conclusions on the reasons for the different ences between the Fucacean belts refer to vegetation patterns, found in exposed biotops the undergrowing species and epiphytes, around Iceland, annual studies of the same among which Plumaria elegans and Mem­ locations would be needed. Detailed studies of bmnojJtem alaia are following up to Horn­ species, characteristic for limited areas should bjarg and e. g. Pol),siphonia lanosa and also be carried out, in order to clear up the Cigartina stellata up to Langanes. causal relationship between the hydrographic In the upper subli ttoral, Laminaria digi­ boundaries and boundaries of the vegetation tata f. stenojJh)'lla was characteristic for ex­ patterns. posed sites of the southern coast whereas in the rest of the coastal area Alaria esculenta seemed to dominate. Local variations. Notable differences in the tide pools vegeta­ tion of selected areas were found around the Beside the pronounced differences, found in coast. the zonation of exposed locations of different The differences in the algal zonation of ex­ parts of the Icelandic coast, local variations in posed and open habitats, as found in various limited areas were also observed. areas of the Icelandic coast, could be due to 'While the first named variations could be different hydrographic conditions, the attributed to the influence of the reigning temperature factor having presumably the ocean currents and thus first of all to the greatest effect on both, the distribution of temperature factor, local variations may be single species and the general appearence of regarded as a response to salinity fluctuations the algal zones. on a rougher scale and to variations in Salinity fluctuations on a smaller scale, as exposure and physical nature of the sub­ encountered in such open locations, are on the stratum, as vvell as to other not fully known other hand less decisive for the features of factors of the environment. GENERAL FEATURES OF THE BENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 25

HYRAFJORDUR REYDARFJORDUR STEINGRIMSFJORDUR August 1964 August 1965 August 1966

T (DC) Sal (%0) T (DC) Sal (%0) T (DC) Sal (%0)

Botn 7,8 9,85 Budareyri 14,0 15,64 Stadara 14,1 11,20 Drangar 8,2 28,33 Kr6kur 11,2 20,54 Thingstadur 11,4 14,21 Skeid 8,7 32,78 Holtastadareyri 9,6 32,65 Brekkuttl11 10,1 33,94 H61ar 9,0 31,41 Grima 6,5 28,07 H61mavik 9,9 33,41 Saltnes 9,2 29,99 Thernunes 5,5 33,84 Vididalsa 9,4 29,24 Hraun 9,4 33,78 Kolmuli 4,5 33,66 Birgistangi 8,8 33,76 Hafnarnes 9,2 34,25 Vattarnesb6t 4,1 33,36 KirkjuMl 6,5 34,23 Ytri 6fa:ra 9,1 34,21 Vattarnestangi 3,5 34,01 MannshOfdi 6,2 34,48 Svalvogar 9,5 34,65 Hafnarnes 3,0 34,66 Hellnanes 6,0 34,14

Hydrographic studies of the Icelandic wat­ fjordur in the northwest, Steingrimsfjordur in ers made in the last decades, as well as recently, the north and Reydarfjordur in the east. (SteHnsson, 1952, 54a, 54b, 62a, 62b) refer to Average salinity and temperature data for oceanic waters surrounding Iceland. some characteristic spots of these three fjords Scanty data are, on the other hand, available will be given for a rough information. about the temperature and salinity conditions All measurements were done during the of the surface water near the coast itself, in­ month of August, though in sequent years. side the fjords and in land-locked areas. All the measurements refer to the surface Some temperature and salinity measure­ water and were made during low tide. ments were done concurrent with the ecologi­ In Dyrafjordur, a progressing increase of cal observations of the algal vegetation. temperature was found along the coast, while These data are of interest in studying the in Steingrimsfjordur and Reydarfjordur the gradually changing vegetation pattern along trends proved to be opposite, the temperature the fj ord coasts. drop being the most expressed in Reydarfjord­ In river outlets, as found in the inner fjord ur. areas, we deal as a rule with a rather rough Salinity values in the inner fjord areas are scale of salinity variations which are reflected however variable, dependant on the nearness of in the benthic algal growth, going gradually the fresh water effluxes. over from an estuarine to a typical marine one. Similiar growth conditions were fouund at Algal zones, found in the fjord proper, the heads of all three fjords discussed, thus low proved to show a likeness all around Iceland. salinities, relativelly high temperatures, ex­ In the innermost estuarine fjord regions a treme shelter and sandy-muddy substrata scattered and non-typical growth was found, which cause the so-called "fjord-effect" on the distinct algal belts being gradually formed algal growth (impoverishement of the flora and with the increasing distance from the inner­ rise of the lower vegetation limit). Species of most river outlet. EnteromorjJha, Ectocarpus, Pylaiella, Cladop­ Changing zonation features were observed hora and Dictyosiphon together with Fucus throughout the fjord coasts, as well as a gradual ceranoides, F. vesiculosus and species of increase of the number of species from, the Enteromorpha, Ectocarjnls, Pylaiella, Cladop. inner towards the outer fjord regions. hom and DictyosijJhon together with Fucus In the outer areas of the fjords, conspicous ceranoides, F. vesiculosus and species of jli[ono­ differences were observed between the three stroma and Porphym were the main elements fjords discussed in the present paper, Dyra- in such biotops. The pattern of the Fucacean 26 ACTA NATURALIA ISLANDICA 21 (1972) ---- zonation along the fjord coasts is however podioides-Rhodymenia palmata for the middle changing from spot to spot. areas solely. Similiar changes in the vegetation pattern The upper sublittoral growth was repre­ throughout the fjord coasts have been des­ sented by Chorda filum in the inner fjord cribed by several authors, e. g. Printz (1926) regions, this species being gradually joined by for the Trondheimsfjord, Sundene (1953) Laminaria saeeharina and Laminaria digitata for the Oslo-fjord, Jorde and KIaves tad and disappearing in the outer fjord regions, (1963) for the Hardangerfjord in Norway. where, finally, under conditions of high ex­ In the lower littoral, zones of different fila­ posure only A laria eseulenta is left. mentous algae proved to be characteristic for If comparing the three fjords in question, the inner and middle areas, whereas belts of the following differences were most obvious in Aerasiphonia spp.-Pylaiella littomlis and the algal zonation of their outer areas: Halosaeeion mmentaeeum-Rhodomela lyeo-

DYRAFJORDUR STEINGRtMSFJORDUR REYDARFJORDUR

Upper littoral: Upper littoral: Upper littoral: Fragmentary Ulothrix 'Well developped Ulothrix Broad and outstanding Ulot­ Uraspom belt. - Urospora belt. hrix - Urasl)om belt.

Lower littoral: Lower littoral: Lower littoral: Cigartina stellata with Leat­ Halosaeeion mmentaeeum ­ Porphyra linearis - Chor­ hesia dittormis or Callit­ Chordaria flagelliformis daria flagelliformis. hamnion m'buseula - Cor­ Patches of Aerasiphonia spp. Extensive Aerasiphonia Spl). allina offieinalis meadows. fields. fields.

Tidal pools: Tidal pools: Tidal pools: Cemmium SI)I). with Cystoe­ Ceramium SI)I). with Cystoc Filamentous brown algae, lonium IJw'lJUrewn, Cor­ lonium purpureum, Cor­ Aerasil)honia SI)P., Porphym all£na offieinalis and Entera­ allina officinalis (rare), miniata, Coilodesme bulli­ morpha lima. gem and Ralfsia fungiformis. Aerasiphonia SI)P. and fila­ mentous brown algae.

SUMMARY The influence of the Atlantic waters, being strongest in the south, diminishes in the 1. The general features of benthic algal zona­ northern and northeastern direction, whereas tion in different areas of the Icelandic coast the East Icelandic coastal area is influenced by are described. the East Icelandic Current, which is of Arctic The algal belts, belonging to different origin. littoral levels are given in their vertical sequ­ 3. Observations revealed that the algal belts, ence in all the profiles, described in this encountered in the lower littoral of exposed paper. and open locations, were the most outsanding. 2. The heterogenity in the patterns of algal Cigm'tina stellata and Callithamnion arbu­ zonation, as observed in different regions, thus SCIlla belts were found on this level in the in the south, south west, north west, north and south and west up to Hornbjarg, whereas in east of Iceland, could be due to the influence the north a Halosaeeion mmentaeeum zone of different hydrographic conditions. was characteristic. In the east Porphym linearis GENERAL FEATURES OF THE BENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 27 and Chonlaria flagellifonnis belts appeared on from place to place, dependant on the degree this level. of exposure and configuration of the littoral Extensive Corallina officinalis meadows slopes. were observed in the Atlantic water regions 6. The stronger the degree of exposure, the up to Hornbjarg, and AcrositJhonia spp. fields less algal zones were as a rule found through­ in the east. out the littoral. 4. Smaller variations were found in the 7. In limited areas, the sequence of algal upper littoral levels. In the south, up to Sme­ zones could change from place to place as a fellsnes, a Pelvetia canaliculata zone was ob­ response to local variations in the environ­ served in the uppermost littoral. mental conditions. In the fjords, the salinity The Ulothrix-Urospora zone, being narrow factor has a profound influence on the or even absent in the south, became gradually appearence and sequence of algal zones. broader and better developed in the northern 8. Regional differences in the zonation patt­ and northeastern direction. In the east, an out­ erns as observed in exposed and open loca­ standing green zone occupied the upper littoral tions, could at the present state of knowledge slopes. be regarded as a function of different tempera­ 5. The Fucacean zonation showed variations ture conditions around the Icelandic coast.

SPECIES NEW FOR ICELAND

As mentioned in the introduction only innermost fjord areas and shallow bays, species which are likely to be the most out­ influenced by fresh water. A record from standing for the vegetation pattern of diff­ 1856 is mentioned by van den Hoek (1963, erent areas of the Icelandic coast are treated. pp. 204) but not mentioned by Helgi J6nsson The collected material is under further in­ (1910). The species Blidingia minima (Nag­ vestigation. Some biotic units, found during eli ex Klitz.) Kylin corresponds to Entero­ field observations, are still to be sorted and mortJha intestinalis f. minima, mentiioned revised. by Helgi J6nsson, and Blidingia marginata Studies of the algal vegetation of the Ice­ (J. Ag.) Dang. to EnteromOj'pha intestinalis f. landic coasts will be continued in the com­ mzcrococca. ing years. Species belonging to the genus Cladophora The present list, however, contains only need further revision. a part of the algal species, occurring in Ice­ landic waters. PHAEOPHYCEAE In accordance with present studies, which Asperococcus echinatus (Mert.) Grev was still are preliminary, the following species found in the area between Olfusa and can be regarded as new for the Icebndic coa­ Thj6rsa. It proved to be outsanding in the stal areas vegetation of the South Icelandic coastal area. Punctaria latifolia Grev., Sphacelaria bipin­ CHLOROPHYCEAE nata (Klitz.) Sauv., Scytosiplwn pygmaeus Blidingia chadefaudii (Feldmann) Eliding, Reinke, l\1.yriactula lubrica (Rupr.) Jaasund Ulva rigida (c. Ag) Thur, Enteromorpha (probably corresponding to Elachista fucicola ahlneriana Bliding, Cladophora oblitterata f. lubrica, mentioned by Helgi J6nsson, 1903). Soderstrom, CladotJhora fracta (VahI) Kiitz. Pylaiella 1'lztJincola (Aresch.) Kylin (by some The last named species was found in the authors regarded as a form of P. littoralis 28 ACTA NATURALIA ISLANDICA 21 (1972)

(eg. "West. 1967). Fucus ceranoides L., not As mentioned in the introduction, the gen­ mentioned by Helgi Jonsson (1903, 1910) is us Ceramium still needs further investigation. common and widespread in estuarine areas Comparing my preliminary data with those all around Iceland, especially in the inner­ of H. Jonsson (1912) the following species most fjord areas. Following transplantation were additionally recorded: Ceramium ares­ experiments in Norway (Munda, 196'1) it chougii Kylin, Ceramium strictum (KLitz.) J. might be possible that this species belongs to Ag., Ceramium secundatul/1 Lyngb. (after Ky­ F. vesiculosus. lin, 1944)). Ceramium jJenincillatum Aresch. (after Kylin, 1944) is according to several RHODOPHYCEAE. authors only regarded as a form of C. fruti­ PorphYH/ abyssicola Kjellm., GloiosijJlwnia culosu.m, while C. jJCdicellatum (Duby) J. Ag. cajJillaris (Huds.) Carm,. ex Berk., Callit­ corresponds to C. l'ubnu/1 val'. jJCdicellatum, lwmnion hookeri (Dillw.) S. F. Gray, Callit­ this variety of C. nlbn/m not being menti­ hamnion tetrargonum (With.) S. F. Gray. oned by H. Jonsson (1912).

LIST OF SPECIES MENTIONED IN THE TEXT

CHLOROPHYCEAE PRASIOLALES Prasiolaceae ULOTRICHALES Prasiola stipitata Suhr. Ulotrichaceae Prasiola furfuracea (Mert.) iVIenegh. Vlothrix £1acca (Dillw.) Thuret Prasiola sp. Vlothrix pseudo£lacca ·Wille Vlothrix spp. (includes also V. sub£laccida CLADOPHORALES ·Wille, V. consociata vVille). Cladophoraceae Rhizoclonium riparium (Roth.) Harvey Ulvaceae Cladophora rupestris (L.) Klitz. Blidingia marginata (J. Ag.) P. Dang. Cladophora oblitterata Soderstrom Blidingia chadefaudii (Feldmann) Eliding Cladophora £lexuosa (lvnlll.) Klitz. Enteromorpha intestinalis (L.) Link. Cladophora fracta (VahI) Klitz. Enteromorpha compressa (L.) Grev. Cladophora glaucescens (Griff. ex Harvey) Enteromorpha prolifera (MUll.) J. Ag. Harvey Enteromorpha ahlneriana Bliding Cladophora sp. Enteromorpha clathrata (Roth.) Grev. (The nomenclature and delimitation of Enteromorpha £1exuosa (vVul£. ex Roth) J. Ag. species ·within this genus is treated from Enteromorpha linza (L.) J. Ag. different aspects by recent authors (e. g. Enteromorpha groenlandica (J. Ag.) Setch. Soderstrom, 1963, van den Hoek, 1963). A et Gardn. (Corresponds to Monostroma groen­ part of my material has kindly been cheked landicum J. Ag. (ex Rosenvinge 1893)). by Soderstrom and the nomenclature used is VIva lactuca L. in accordance with his aspects.) VIva rigida (C. Ag.) Thur. Chaetomorpha melagonium (VITeb. et :Mohr.) VIvaria obscura (Klitz) Gayral Klitz. Chaetomorpha capillaris (Klitz.) Borg. Monostromataceae Monostroma grevillei (Thuret) ·Wittrock Acrosiphoniaceae Monostroma undulatum "Vittrock Vrospora penicilliformis (Roth.) Aresch. GE~ERAL FEATURES OF THE BENTH1C ALGAL ZONAT10:'< AROUND THE lCELAND1C COAST 29 ._----_.._._------~~-----

Urospora spp. Desmarestia viridis (Mi.llI.) Lam. Spongomorpha aeruginosa (L.) Hoek Desmarestia ligulata (Light£.) Lam. Acrosiphonia sonderi (Klitz.) Kornmann Acrosiphonia arcta (Dillw.) J. Ag. SPHACELARIALES Acrosiphonia centralis (Lyngb.) Kjellm. Sphacelariaceae Acrosiphonia spp. Sphacelaria radicans (Dillw.) C. Ag. (All the Acrosiphonia material has not yet Sphacelaria britannica Sauv. been determined with certainity, due to a Sphacelaria bipinnata (Klitz.) Sauv. wide range of morphological variations, ob­ Chaetopteris plumosa (Lyngb.) Klitz. viously induced by different ecological factors. A part of dried and living material SCYTOSIPHONALES was sent to Kornmann and is under investi­ Scytosiphonaceae gation). Scytosiphon lomentaria (Lyngb.) J. Ag. Scytosiphon pygmaeus Reinke Petalonia fascia (Mi.llI.) Kuntze PHAEOPHYCEAE Petalonia zosterifolia (Reinke) Rosenvinge

ECTOCARPALES DICTYOSIPHONALES Ectocarpaceae Tilopteridaceae Ectocarpus confervoides (Roth.) Le Jol. Pylaiella littoralis (L.) Kjellm. (different forms) Pylaiella rnpincola (Aresch.) Kylin Ectocarpus siliculosus (Dillw.) Lyngb. Ectocarpus faciculatus Harv. Striariaceae Ectocarpus spp. Stictyosiphon tortilis (Rupr.) Reinke Spongonema tomentosum (Hmls.) Klitz. Giffordia hincksiae (Harv.) Hamel Punctariaceae Punctaria plantaginea (Roth.) Grev. Ralfsiaceae Punctaria latifolia Grev. Ralfsia vcrrucosa (Aresch.) J. Ag. Asperococcus echinatus (Mert.) Grev. Ralfsia fungiformis (Gunn.) Setch. et. Gardn. Ralfsia spp. Dictyosiphonaceae Dictyosiphon foeniculaceus (Hmls.) Grev. Elachistaceae Dictyosiphon corymbosus Kjellm. Elachista fucicola (Vell.) Aresch. Dictyosiphon chordaria Aresch. d. Myriactula lubrica (Rupr.) Jaasund Dictyosiphon ekmani Aresch. Dictyosiphon spp. Chordariaceae Coilodesme bulligera StromE. Leathesia difformis (L.) Aresch. Eudesme virescens (Carm. ex Harv. in Hook.) Chordaceae J. Ag. Chorda filum (L.) Stackh. Chordaria flagelliformis (O.F. Mi.llI.) C. Ag. Chorda tomentosa Lyngb.

DESMARESTIALES LAMINARIALES Desmarestiaceae Laminariaceae Desmarcstia aculeata (L.) Lam. Laminaria digitata (Hmls.) Lom. ACTA NATURALIA ISLANDICA 21 (1972) 30 ------" f. stenophylla (Harv.) Foslie CRYPTONEMIALES f. cucculata Le J 01. Dumontiaceae Laminaria hyperborea (Gunn.) Foslie Dumontia incrassata (Mull.) Lam. Laminaria saccharina (L.) Lam. Dilsea edulis Stackh. " £. linearis J. Ag. Hildenbrandia prototypus Nardo f. latifolia Kjellm. f\laria esculenta (L.) Grev. Saccorhiza dermatodea (De la Pyl.) J. Ag. Corallinaceae Corallina officinalis L. FUCALES Clathromorphum circumscriptum (Sromfelt) Fucaceae Foslie Clathromorphum sp. FUClIs vesiculosus L. Phymatolithon polymorphum (L.) Foslie " f. sphaerocarpus J. Ag. Ph. spp. (includes Ph. lenonnandii (Aresch.) Fucus ceranoides L. Adey, Ph. rugulosum Adey, Ph. laevigatum FUClIs serratus L. (Foslie) Foslie) Fucus spiralis L. Dermotolithon sp. FUClIs distichus L. emend. PO'well Lithothamnion g-laciale Kjellm. " subsp. edentatus (De la Pyl.) Powell Lithothamnion tophiforme Unger subsp. anceps (Harv. et \IVard ex Carrut­ Lithothamnion spp. hers) Powell Leptophytum spp. (includes L. laeve " subsp. evanescens (C. Ag.) Powell (Strom£.) Adey, L. foecundum (Kjellm.) " subsp. distichus Powell Adey Ascophyllum nodosum (L.) Le Jol. Pelvetia canaliculata (L.) Decne et Thur. The crustose, Corallines, collected in upper water layers of the Icelandic coast have not yet been determined as a whole. Only a part RHODOPHYCEAE of the determined material is enumerated in the list, while in the text, most frequently BANGIALES only the genera are mentioned for locations Bangiaceae where they proved to be outstanding in the vegetation pattern. Bangia fUScopUTpurea (Dillw.) Lyngb. Porphyra miniata (Lyngb.) C. Ag. A part of my material was determined by Porphyra abyssicola Kjellm. d. Adey and my own determinations are based Porphyra linearis Grev. on Foslie's exicate as well as on a part of Porphyra umbilicalis (L.) J. Ag. Adey's collection, which was kindly given to f. umbilicalis (L.) J. Ag. my disposition. " f. laciniata (Lightf.) ThUTet The crustose Corallines in deep-water Porphyra spp. layers around Iceland were studied by Adey (1968). ACROCHAETIALES Acrochaetiaceae Kallymeniaceae Acrochaetium alariae (J6115s.) Born. Euthora cristata (C. Ag.) J. Ag. Rhodochorton pUTpUTeum (Lightf.) Rosenv. Rhodochorton spp. (includes R. penicilli­ forme (Kjellm.) Rosenv., R. membranaceum Squamariaceae Magnus, R. sp. Peyssonelia rosenvingii Schm. in Rosenv. GENERAL FEATURES OF THE BENTHIC ALGAL ZONATION AROUND THE ICELANDIC COAST 31

G1oiosiphoniaceae Antithamnion boreale (Gobi) Kjelhl1. G1oiosiphonia capillaris (Huds.) Carm. ex Antithamnion sp. Berk. Plumaria elegans (Bonnem.) Schmitz. Ptilota pectinata (Gunn.) Kjellm. Ceramium rubrum (Hucls.) C. Ag. GIGARTINALES Ceramium areschougii Kylin Gigartinaceae Ceramium penicillatum Aresch. Chondrus crispus Stackh. Ceramium circinatum (Klitz.) J. Ag. Gigartina stellata (Stackh.) Batters Ceramium strictum Harv. Ahnfe1tia p1icata (Hucls.) Fries Ceramium shuttleworthianum (Kiitz.) Silva Rhodophyllis dichotoma (Lepech.) Gobi Ceramium spp. (includes several species, Cystoclonium purpureum (Huds.) Batters. which still need further investigation, such as. Ceramium fruticulosum (Klitz.) J. Ag., Cera­ Cruoriaceae mium pedicellatum (Duby) J. Ag., Ceramium secundatum Lyngb., Ceramium arborescens J. Petrocelis hennedyi (Harv.) Batters Ag., Ceramium atlantium Petersen together with yet undetermined material). Phyllophoraceae Phyllophora membranifolia (Good. et \IVood.) Delesseriaceae .J. Ag·. Membranoptera alata (Hucls.) Stackh. Phyllophora brodiaei (Turn.) Endl. Delesseria sanguinea (Hucls.) Lam. Phycodrys rubens (L.) Batt. P10camiaceae Plocamium coccineum (Huds.) Lyngb. Rhodomelaceae Polysiphonia urceolata (Lightf. ex Dillw.) Soleriaceae Grev. Turnerella pennyi (Harv.) Schmitz Polysiphonia arctica J. Ag. Polysiphonia nigrescens (Huds.) Grev. RHODYMENIALES Polysiphonia lanosa (L.) Tandy Rhodomela lycopodioides (L.) C. Ag. Rhodymeniaceae Odonthalia dentata (L.) Lyngb. Rhodymenia palmata (L.) Grev. Halosaccion ramentaceum (L.) J. Ag. CYANOPHYCEAE Lomentariaceae Lomentaria orcadensis (Harv.) ColI. ex Taylor were not included in the present survey. Lomentaria clavellosa (Turn.) Gaill. Nevertheless the following species, which were outstanding and belt-forming in the north and east of Iceland are worth to be CERAMIALES mentioned: Ceramiaceae Calothrix crustacea Schousb. and Thur. Callithamniol11l1 arbuscula (Dillw.) Lyngby. Calothrix scopulorum (/\IVeb. et Mohr./ c. Callithamnion hookeri (Dillw.) S. F. Gray Ag.) Born. et Flah. Callithamnion tetrargonum (\"Tith.) S. F. Gray Petalonema sp. Antithamnion 'floccosum (0. F. MinI.) Kleen. Schizothrix calcicola (c. Ag.) Com.

This j)(tjJer was received in October 1969 and accejJted tor publication Tn Acta Natumlia Islandica during 1970. The Editor. 32 ACTA NATURALIA ISLANDICA 21 (1972)

ACKNO~WLEDGEMENT

The author feels greatly indebted to the Icelandic Science Foundation, which has financially supported the present algological investigations around the Ice­ landic coast from 1963 up to this date. Futher thanks are due to :Mrs. Th6runn Th6rdard6ttir and Director J6n J6ns­ son, Marine Research Institute, Reykjavik, for offering' me working facilities at the institute, as well as to Mr. J6hannes Briem for his great help during my work. Special thanks are due to Prof. Dr. T. Levring and Dr. J. Soderstrom, ~Marine Botanical Institute, University of Gothenbourg, to Dr. Carl Bliding, Boras, Dr. P. Kornmann, Biological Station of Helgoland, to Dr. Drouet, Academy of Natural Science Philadelphia, and to Dr. I'V. H. Adey, The Museum of Natural History, IVhasington, for their help and advices. The succes of the field work was greatly dependant on the help and assistance of many people living in the coastal areas investigated who gave me possibilities to live in their homes. To all who have helped I express my sincerest thanks.

REFERENCES. 1891: Contribution to knowledge of marine algae of Norway II. Ibid. 14. Adey, W. H. - 1966: The distribution of saxicolous Gronlund, C. - 1879: Tillceg til Kjellmans Af­ corallines in the northwestern North Atlantic. handling. Bot. Tidskr. B. 3, rcekke 3. Journ. Phyc. 2 (2), 49-54. Hjaltalin, O. ]. - 1830: fslenzk Grasafrce<'5i. 1968: The Distribution of Crustose Cor­ K6benhavn - Reykjavik. allines on the Icelandic Coast. Science in Ice­ Hoek, C. van den. - 1963: Revision of European land, Ann. Vol., Reykjavik, 1968. species of Cladophora. Leiden. Bliding, C. - 1944: Zur Systematik del' schwedi­ Hooker, TV. ]. - 1813: Journal of a tour around schen Enteromorpha. Bot. Notiser, 97. Iceland in the summer of 1809. London. 1963: A critical survey of European taxa in Hygen, G. and Jorde, I. - 1934: Beitrag zur Ulvales. Part I. Opera Botanica, 8:3. Kenntnis del' Algen£lora del' norwegischen 1968: A critical survey of European taxa in ~Westkiiste. Bergens Mus. Arbok 1934, Natur­ Ulvales. Part II. Bot. Notiser, 121, 4. vidensk. Rekke N. 9. B6rgesen, F. - 1904: am Algevegationen ved ]aasund, E. - 1957: :iHarine algae from Northern Fceroernes Kyster. Kobenhavn og Kristiania. Norway. Bot. Notiser, llO, 2. Gyldendals Forlag'. 1965: Aspects of the marine algal vegetation Borgesen, F. and ]Onsson, H. - 1908: The distl'i­ of North Norway. Bot. Gothoburgensia IV. r'ution of marine algae in the Arctic sea and ] onsson, H. - 1901: The marine algae of Ice­ the northennost part of the Atlantic. Botany land. I. Rhodophyceae. Bot. tidskr. Bd. 24. of Fceriies. Part III. K6benhavn. 1903: Idem. II. Phaeophyceae, III. Chloro­ Dixon, P. S. - 1960: Studies on marine algae of phyceae. Ibid. Bd. 25. the British Isles: Ceramium shuttleworthi­ 1910: am algevegetation ved Islands kyster. anum (Kiitz.) Silva. .J. mar. biol. Assoc. UK, Thesis. K6benhavn. 39. 1912: The j\'Iarine Algal Vegetation. The Eyjolfsson, F. - 1861: Brjef til J. Hjaltlins. Is­ Botany of Iceland, Vol. I. I, ed. by K. L. lending-ur, 2, 4, 5. Rosenvinge and E. vVarming. Copenhagen. Foslie, M. H. - 1890: Contribution to kno,vledge Jonsson, S. - 1966: Le commencement du peuple­ of marine algae of Norway, I. East Finn­ ment bentique des cotes rocheuses du Surtsey, marken. Tromsii rvIus. Aarshefter 13. la nouvelle lIe volcanique dans l'Atalnti- GENERAL FEATURES OF THE BENTHIC ALGAL lO:'-iATlON AROUND THE ICELANDIC COAS1' 33

que Nord. C. R. Acad. Sci., France, 262, Mohr, N. - 1786: Forsag til en Islandsk Natur­ 915-918. historie. Kabenhavn. 1970: Studies on the Colonization of Marine Munda, I. - 1964: The quantity and chemical Benthic Algae at Surtsey in 1968. Surtsey composition of Ascophyllum nodosum (L.) Research Progress Report V. Le Jol. along the coast between the rivers Jorde, I. and Klavestad, N. - 1963: The natural DUusa and Thj6rs,i (Southern Iceland). Bot. history of the Hardangerfjord. The benthonic marina Vol. VII, 1-4. algal vegetation. Sarsia 9. Bergen. 1964: Observations on variation in form and Kjellmann, F. R. - 1883: The Algae of the Arctic chemical composition of Fucus ceranoides L. Sea. Kgl. Sv. Vet. Akad. Handl. Vol. 20. Stock­ Nova Hedwigia. B. VIII. holm. 1969: Differences in the algal vegetation of 1879: Bidrag til kannedomen om Islands two Icelandic fjords, Dyrafjardur (West Hafsalgsflora. Bot. Tidskr. B. 3. R;:ekke 3. Iceland), and Reydarfjardur (East Iceland). 3. Proe. VIth Seaweed Symp. 1968. 1906: Zur Kenntnis der marinen Algenflora 1970: Ranns6knir a botngr6<'5ri vi<'5 strendur von Jan ?vlayen. Arkiv for Bot. Bd. 5. Islands 1963 til 1968. Nattllrufr;:edingurinn. Vol. 40 (1-25). Kornmann, P. - 1961: Zur Kennthiss der Porp­ 1970b: A note on the densites of benthic mar­ hyra Arten von Helgoland. Helgol. 'Niss. ine algae along a rocky slope in Faxafl6i, lVIeeresundters. B.8. Southwest Iceland. Nova Hedwigia. B. 19. 1962: Eine Revision der Gattung Acrosi­ Miiller, O. F. - 1770: Enumeratio Scirpium in Is­ phonia. Ibid. B.8. landia Sponte crescentium. Nova Acta Acad. 1964: Die Ulothrix Arten von Helgoland. Nat. Curios. IV., pp 203-215. Ibid. B 11. Parhe 1\1., and Dixon, P. - 1964: A revised check­ K)llin, H. - 1907: Studien liber die Algenflora list of British marine algae. J. mar. bioI. der schwedischen vVestkiiste. Akad. Avh. Assoe. UK, 44. Upsala. 1968: Check-list of British marine algae­ 1918: Svenska vastkustens algregioner. Svensk. second revision. Ibid. 48. Bot. Tidskr. 12. Printz, H. - 1926: Die Algenvegetation des 1944: Die Rhodophycean der schwedischen Trondheimfjordes. Skr. Norske. Vidensk. 'Vestkiiste. Lunds Univ. Arsskr. N. F. Avd. 2. Akad. I. - :Mat. - Nat. Klasse, 5. B. 40. 2. 1947: Die Phaeophyceem der schwedischen Rose/1Vinge, L. K. - 1879: Bidrag til Kundskapen om SI;:egterne Ulothrix og Conferva. Bot. Westkiiste. Ibid. B. 43. 4. Tidskr. B. 3, r;:ekke 3. 1949: Die Chlorophyceen der schwedischen 1893: Granlands Havalger. J'l'Iedd. om Gran­ Westkiiste. Ibid. B. '15. 4. land. Vol. 3. Levring, T. - 1937: Zur Kenntnis der Algenflora 1898: Om Algevegetation ved Granlands der norwegischen vVestkiiste. Lunds U niv. Kyster. Ibid. Vol. 20. Arsskr. N. F. Avd. 2. Bd. 33. 1910: On the marine algae from the north­ 1959: Distribution verticale de la vegetation east Greenland. Medel. om Granland, 43. algale marine specialement en Scandinavie. Sernander, R. - 1917: De nordeuropeiska hafvens Colloque Internat. C. N. R. S., 81, Paris. vaxtregioner. Svensk. Bot. Tidskr. 11. Levring, T., HojJpe, H. A. and Schmid, O. J. ­ Sjostedt, L. G. - 1928: Litoral and supralitoral 1969: j'darine Algae. Hamburg. studies on the Scanian shore. Lunds Univ. Lewis, J. R. - 1964: The ecology of rocky shores. Arsskr. N. F. 24, N. 7. London. Stefdnsson, U. - 1954a: Surface temperature in Ice­ Lindsaj', W. J. - 1861: The flora of Iceland. landic coastal waters during 1949-53. Fjalrit Edinb. New. Phil. Journ. Vol. 14 (64-101). Fiskideildar, 4 (1-23). Lund, S. - 1959: The marine algae of east Green­ 1952: Hydrographic conditions in the Iceland land. II. Geographic distribution. Medd. am Sea 1951. Ann. bioI. vol. 8 (27-30). Granland. Bd. 156, N. 2. 1954b: Temperature variations in the North 1954: The algal zones in East Greenland and Icelandic coastal area. Rit Fiskideildar, Vol. their ecological factors. Rapp. comm. 8 eme II. N. 2 (1-27). Congr. Internat. Bot. sect. 17. Paris. 1962a: Te salinity of the shores of the south iVlachenzie, G. S. - 1812: Travels in the Island of west Iceland. Ibid. N. 9 (1-26). Iceland, during the summer of the year 1810. 1962b: North Icelandic '''Taters. Ibid. vol. III Edinburgh. (1-269). 34 ACTA NATURALIA ISLANDICA 21 (1972)

Stephenson, T. A. and Anne. - 1949: The universal Sundene, O. - 1953: The algal vegetation of the features of zonation between tide-marks on Oslo fjord. Skr. Norske Vidensk. Akad. Oslo 1. rocky coasts. .Journ. Ecol. 37 (2). l'vIat. - Nat. K1. 1961: Life between tide-marks in North Svendsen, P. - 1959: The algal vegetation of America. Ibid. 49. Spitzbergen. Norsk Polarinst. Skr. N. 116. Stromfelt, H. F. G. 1886a: Einige Hir die Wissen­ Vahl, 11'[' - 1840: Liste des plantes que l' on schaft neue Meeresalgen aus Island. Bot. suppose d'exister en Islande. Paris. Centralb1. Bel. 26. Wennberg, T. - 1950: The distribution of certain 1886b: Om algevegetation vid Islands kuster. marine algae on the Norwegian coast. Acta Akad. Afh. Goteborg. Hort. Gothob. 18. Soderstrom, ]. - 1963: Studies in Cladophora. West, ]. A. - 1967: Pylaiella littoralis f. rupin­ Botanica Gothburgensia, 1. cola from ii\Tashington: the life - history in 1965: Equivalent algal zones in 'Western culture. J. Phyco1. 3, (3). Sweden and the British Isles. Bot. Gotho­ Zoega, ]. - 1772: Flora Islandica. In E. Olafsson: burgensis 3. Reise igiennem Island. Anden Dee!. Soroe. 36 ACTA NATURALIA ISLANDICA

EXPLANATION OF PLATES

Plates 1-7: Profiles schemes 1-7: 1 Smefellsnes 2 Dyrafjordur inner area Dyrafjordur - middle area 3 Dyrafjordur - outer area '1 D)lrafjordur - outer area 5 Steingrimsfjordur - outer area Grimsey 6 Reydarfjordur - outer area 7 Reydarfjordur - outer area The profile transections, demonstrated on the algal zonation in selecte:l areas and do not Plates 1-7, indicate the general feature of refer to particular locations.

Plates 8-15: Figures 1-16:

Fig. 1. Porphyra umbilicalis belt of Smefellsn~s, Fig. 2. Gigartina stellata zone below Ascophyllum nodosum at Hellnar, Smefellsnes. Fig. 3. Fucus spiralis and Fucus vesiculosus zones on rocky slopes at Smdellsnes (Pylaiella rupincola under the barnacle belt). Fig. 4. Detail from the same zones as Fig. 3: Pylaiella rupincola, Acrosiphoina spp., Scytosiphon pygmaeus and Rhodochorton spp. in the Fucus zone. Fig. 5. Upper fringe of Ascophyllum nodosum zone in the outer part of Dyrafjordur (Ytri 6fcera). Fig. 6. Upper fringes of Fucus vesiculosus and Ascophyllum nodosum zones in the same area as Fig. 5. Fig. 7. Longufjorur at Sncefellsnes. Filamentous algae (species of Ectocarpus, Entero­ morpha and Dictyosiphon) with scattered Fucus vesiculosus on a sandy ground. Fig. 8. Scattered Fucacean gTowth at Drangar in the inner part of D)lrafjordur (Fucus vesiculosus, Fucus ceranoides, Ascophyllum nodosum). Fig. 9. Algal zonation at Reykjanes (Sandvik): FUClIS spiralis - F. vesiculosus - Asco­ phyllum nodosum - Gigartina stellata - Corallina officinalis - Laminaria di­ gitata f. stenophylla. Fig. 10. Algal zonation in the outer part of Steingrimsfjordur: Fucus distichus ssp. edentatus - Halosaccion ramentaceum with accompanying species ­ Laminaria digitata f. cucculata. Fig. 11. FUClIS distichus ssp. edentatus - Halosaccion ramentaceum - Laminaria digi. tata belts from the same area as Fig. 10, Fig. 12. Laminaria hypcrborea in the ou tel' part of D)lrafjordur. Fig. 13. Laminaria saccharina f, linearis belt below Gigartina stellata at Reykjanes. Fig. 14. Alaria csculenta belt (narrow form) at Vattarnes in Reydarfjordur. Fig. 15. Extremely exposed rocky formations between Vattarnes and Hafnarnes outside Reydarfjorclur. Fig. 16, Acrosiphonia spp. and lower down Chordaria flagelliformis in the oouter part of Reydarfjdrdur. ZONATION - SNfEFELLSNES (STAKKHAMAR) Plate 1

EXPOSED SIDE SHELTERED SIDE

HIGH TIDE LEVEL Porphyra umbilicalis

Ulothrlx sp. -Urospora sp. Bangia fuscopurpurea Blidingla minima Ulothrix spp.

Fucus distichus edentatus Acroslphonia spp.­ Fucus vesiculosus Polysiphonla urceolata Ceramium spp. Gigartina stellata Porphyra abyssicola Dumontla incrassata Cystocionium purpureum Rhodymenla palmata Rhodymenia palmata- Rhodomela iycopodioi Uiva lactuca

Chaetomorpha . Ciadophora rupestris Ii'-elagonlum

(HELLNAR)

Prasiola sllpltata

riparium HIGH TiDE LEVEL

Porphyra umbilicalis ~_-<..u,,_ Ulothrix flacca .....,

INNERMOST ESTUARY

HIGH TIDE LEVEL - Enteromorpha intestinalis ------.- -;- -. - - - Ectocarpus spp. SCATERRED Pylalella Iltloralis Fucus ceranoides GROWTH Fucus VeSiC_UIOS~ ~ \ Dictyosiphon chordaria cf. ~ '..'': '. -.' . ¥t~~ctu~"" .

Enteromorpha ahlneriana LOW TIDE LEVEL

INNER FJORD AREA

HIGH TIDE LEVEL ~~ ------­ Ulothrix spp.

Ascophyllum nodosum Fucus distichus evanescens FilamentolJs algae: Ectocarpus spp .. Dictvosiphon foeniculaceus, D. Chordaria f1agelliformis, Enteromorpha spp.,--'--..u:<::::...~~_)~ Chaetomorpha tortuosa

MIDDLE FJORD AREA

HIGH TIDE LEVEL

Fucus vesiculosus Ascophyllum nodosum Fucus distichus edentatus Fiiamentous algae: Rhodymenia palmata-Haiosaccion ramentaceum- Rhodomela Iycopodiolden

LOW TIDE LEVEL ZONATION - WESTERN FJORDS (DYRAFJOR8UR) Plate 3 OTHER FJORD AREA

SHELTERED LOCATION

HIGH TIDE LEVEL

Enteromorpha intestinalis Fucu~ vesiculpsus ucus distichus edentatus Fucus distichus evanescens

Raifsia fungiformis

Ulva iactuca

LOW TiDE LEVEL

Polysiphonia arctica Aiaria esculenta Laminaria digitata Laminaria saccharina

SEMI-EXPOSED LOCATION

nodosum Fucus distichus edentatus Rhodymenla palmata Halosaccion ramentaceum

LOW TIDE LEVEL Alaria esculenta Laminaria digitata Laminaria saccharina

HEAVILY EXPOSED LOCATION

Acrosiphonia arcta Gigartina stellata - Leathesia difformis

LOW TIDE LEVEL ZONATION - WESTERN FJORDS (DYRAFJORfJUR) Plate 4 OUTER FJORD AREA

HEAVILY EXPOSED LOCATION

Prasiola stipitata Rhizocl"onium riparium HIGH TIDE LEVEL

-"'LA.u-..-_·,,-- - Porphyra umbmciills------­ Ulothrix spp. Bangia fuscopurpurea Fucus dis~chus anceps Acrosiphonia arcta Gigartina stellata-Leathesia difformis

Corallina officinalis

OPEN AREA

EXTREMELY EXPOSED LOCATION HIGH TIDE LEVEL

------Porphyra umbilicalis - - - - ­ Ulothrix sp.-Urospora sp.

Fucus distichus anceos Rhodymenia palmata Halosaccion ramentaceum Rhodomela Iycopodioides

Callithamnion arbuscula

LOW TIDE LEVEL------...... --4....;------ZONATION - NORTHERN ICELAND (STEINGRfMSFJORDUR) Plate 5

OUTER FJORD AREA HIGH TIDE LEVEL ------~--~-~------~------Bangia fuscopurpurea Fucus splralis Fucl1s vesiculosus Fucus dlstichus edentatus Ceramium rubrum -C. areschougii Scytoslphon lomentaria Rhodymenia palmata Halosacclon ramentaceum Petnlonia spp. Rhodomela iycopodioides Chordaria f1agelliformis - - ToW ilbELEvEI ------

GRIMSEY OFF NORTHERN ICELAND

EXPOSED SIDE SHELTERED SIDE Prasiola stipitata Rhizocionium riparlum

Porphyra umbilicalis l:3angia fuscopurpurea Ulothrlx spp. Ulothrix sp..-Urospora sp. Rhodochorton sp. Petalonia fascia dwarfish Petalonia zosterifolia Porphyra umbilicalis dwarfish spesimens Fucus dislichus anceps Fucus spiralis

Fucus vesiculosus Fucus dlstichus edentatus

normal specimens Scytosiphon lomentaria Petalonia spp. Rhodymenia palmata Halosaccion ramentaceum ZONATION - EASTERN ICELAND (REYDARFJORDUR) Plate 6

OUTER FJORD AREA

MODERATELY EXPOSED LOCATION

Prasiola stipitata Rhizocionium riparium HIGH TIDE LEVEL

_~~~~~::::;-=::::::ASCOPhYiIUm nodosum Fucus distichus edentatus Fucus distichus distichus Scytosiphon lomentaria Halosaccion ramentaceum Rhodvmenia palmata Rhodomela iycopodioides __Clloilladg lLageliiformis

HEAVILY EXPOSED LOCATION

Prasioia stipitata

Porphyra umbilicalis Uiothrix spp. Blidingia minima' Acrosiphonia peniciliiformis cf. Fucus distichus anceps

'k Acrosiphonia sp.-Monostroma groenlandicum Haiosaccion ramentaceum f. robustum LOW TIDE LEVEL Cho~a.':!-a flageliiformis ZONATION - EASTERN ICELAND (REYDARFJORDUR) Plate 7

OUTER FJORD AREA

HEAVILY EXPOSED LOCATION EXTREMELY EXPOSED LOCATION

HIGH TIDE LEVEL

Prophyra umbilicalis

Bangia fuscopurpurea

Ulothrix spp.­ Urospora sp. green layer: Fucus distlchus Ulothrix spp.­ anceps Uropora sp.

Acrosiphonia sp.

Rhodochorton so.

Porphyra linearis Porphyra linearis

Rhodymenia palmata Halosaccion ramentaceum Rhodomela Iycopodioides

LOW TIDE LEVEL Chordaria flagelliformis

Alaria esculenta narrow form Plate 8

Fig. 1. PorlJhyra umbilicalis belt of Smefellsnes.

Fig. 2. Cigartil1a stellata zone below I1sc01Jh)lllu1n 110­ dosu1n at Hellnar, Smefellsncs. Plate 9

Fig. 3. FUCl/S sjJiralis and FUCl/S vesicu/osus zones on rocky slopes at Sn

Fig. 4. Detail from the same zones as Fig. 3: Py/aie/la rUjJinco/a, AcrosijJhonia spj]., Scytosij]hon j]ygma­ eus and Rhodochorton sj]j]. in the FUCl/.s zone. Plate 10

Fig. 5. Upper fringe of AscojJ!zyllum nodosum zone in the outer part of Dyrafjorclur (Ytri Ofa:ra).

Fig. 6. Upper fringes of Fucus vesiculosus and AscojJ!z'yllum nodosum zones in the same area as Fig. 5. Plate 11

Fig. 7. Longufjorur at Smefellsnes. Filamentous algae (species of Eclocar/nls, Enleromor/)!la and Dic­ l)lOsij)!lon) with scattered Fucus vesiculosus on a sandy ground.

Fig. 8. Scattered Fucllcelln growth at Drangar in the inner part of Dyrafjiirdur (Fucus vesiculosns, Fucus ceranoides, AscojJ!lyllum noclosum). Plate 12

Fig. 9. Algal zonation at Reykja­ nes (Sandvik): Fuclis sf)ir­ a/is-F. vesicu/osus-Asco­ f)1I)'//um nodosum-Gigar­ tina ste/lata-Coral/ina offcina/is-Laminaria di­ gitata f. stenof)1I)'l/a.

Fig. 10. Algal zonation in the outer part of Steingrimsfjiirdur: Fuclls distichus SSf). eden­ tatus-Ha/osaccion ramentace­ 11m with accompanying spec­ ies - Laminaria digitata f. cuccu/ala. Plate 13

Fig. II. Fueus distiehus sst). edelltatus-Halosaecioll ramellt(/cellln-Lamillaria digitata belts from the same area as Fig. 10.

Fig. 12. Laminaria hyperborea in the outer part of Dyrafjorclur. Plate 14

Fig. 13. Laminaria silccharinil f. linearis belt below Ci­ gartina stellata at Reykjanes.

Fig. 14. Alaria esculenta belt (narrow form) at Vattarnes in Reydarfj6rdur. Plate 15

Fig. 15. Extremely exposed rocky formations between Vattarnes and Hafnarnes oqtside Reydarfjordur.

Fig. 16. AcrosijJhonia spp. and lower down Chordaria flagelli­ tormis in the out­ er part of Reydar­ fjordur.