Annotations of the seaweed geographical distribution in the Atlantic Ocean North of Equator, in the Mediterranean and in the Baltic
by FREDRIK RUTGER AULIN
translated by Algologia


[CHAPTER 3. Continues.]

Order 3. Dictyotales [as Dictyotaceae]

The algae which belong to this order exhibit numerous peculiarities, both as regards morphological characters as also phytogeographical features. These plants love exceptionally the warm seas, and in these we should seek to find most of the species belonging to the family; from the warmer seas they extent both in the north and in the south, but the number of species and individuals apparently diminishes so that from the rather rich family only just few [species] reach so far as England. On the American coast a similar situation takes place; they occur very sporadically north of Florida; south of this cape they occur in such great amounts, that, like the Fucaceans's on our shores, leave their characteristic stamp on the coastal vegetation. They thrive in the marine water and do not exist in bays with brackish one. They even occur in rock pools in temperate seas, where the sea water is warmed up by the sunlight, demonstrating their preference of a higher temperature. Apart from that they occur in larger numbers in the tropics, they also show a higher organization there than in temperate waters. They do not go deep but remain between ebb and flood or just below the water level. About half of the known species are encountered in the here examined areas. Species of them occur mainly in the Mediterranean, the Central America and the Canaries; likewise, a couple of species are found on our coasts but not one of them goes in the Baltic. The main genus Dictyota has many species in Cadiz, in the Mediterranean and on the coast of the Gulf of Mexico; outside the examined regions, several species occur in the Indian and in the Pacific Oceans; Dictyota dichotoma (Huds.), the only one occurring on the Swedish west coast, has a very widespread distribution; apart from the Atlantic and the Mediterranean, it is also found at the Cape of Good Hope, New Zealand, South America, and elsewhere. Most of the species of the genus Zonaria are found within the examined regions, the other species occur in the Indian and Pacific Oceans; Taonia has all of its species within the Mediterranean and the warmer parts of the Atlantic. The genus Padina has one species, P. pavonica (L.), that like Dictyota dichotoma has an apparently widespread geographical distribution; it probably also occurs on our west coasts. In the Mediterranean and Central America, Haliseris [Dictyopteris] has a few species; the rest are found in the Indian and Pacific Oceans. (Outside the examined regions, several other genera exist.)

Order 4. Fucales [as Fucaceae]

This order is apparently rich in species and important, since it nearly comprises about half of the known olive-colored brown algae. With respect to seaweed distribution, the Fucales are also highly interesting, particularly as they form associations that cover long parts of the seashores from the tropics to the polar seas; one could reasonably say that they represent 3/4 of the entire vegetation within the particular zones they are restricted to. Species belonging to the family Fucaceae are met with in all seas; even in the Baltic is the family represented as far north as Soederhamnskaeren [c. 60 N]. In the Atlantic, north of Equator, the species number is not that large; but the number of individuals is so much larger. More than half of the known Fucaceae belong to the genus Sargassum, that in the tropics and subtropics is represented by some 130 species, of which just a few occur within our regions; they mainly occur in the Pacific Ocean, where they are distributed between the 45 N and 45 S latitude. Among the species occurring in the Atlantic, S. bacciferum (Turn.) deserves to be mentioned, since it forms the so called Sargasso Sea. In the middle of the Atlantic between the 20 and 40 N latitude, it covers a surface of about 4.000.000 square km, an area 5 times as big as the entire Sweden. This algal mass is floating on the surface with the help of the Gulf Stream. A few similar but smaller concentrations exist in some other places. We consider that this alga, which grows in large amounts on the North American coast, has originally drifted away in the Atlantic; later the drifting masses were affected by the influence of the Gulf Stream, and now continue to grow vegetatively and never reproduce sexually; it is true that this dispersal of S. bacciferum from the American coast goes on even today; but the largest parts of these colossal masses must have been produced locally through vegetative propagation of previously dispersed individuals to that place. Because S. bacciferum that grows [attached] on the coast reproduces via spores. Except of this species, the genus has a few more within the examined regions, partly on the American coast, and partly in the Mediterranean; one species even occurs in the Atlantic just outside the Gibraltar Straits, on the coast of Spain, Portugal as well as in North Africa. Of course, any Sargassum is not found in the North Sea; we may consider that the genus is here represented by Halidrys, that extends down to the Canaries, while on our coast it is distributed between the Sound and North Cape. The genus Fucus is very important, particularly to us; species of this genus, likewise of its closely related Fucodium [Pelvetia] and Halicoccus [Ascophyllum], are certainly found outside the Atlantic north of Equator, but it is in this region they really belong to. They occur much more abundantly on the European than the American coast, where they are found in a much smaller area, generally limited to the NE part. On the North American central and south coasts, they occur sporadically, as it has been described in the former part of this thesis; with a few exceptions, species of this group are also lacking in the Mediterranean and the Adriatic Seas. Instead of these genera, the genus Cystoseira is represented in these seas with many species, few of which extend through the Gibraltar up to England; on the American coast, this genus is absent; a few other species are found outside the regions here investigated; therefore the genus [Cystoseira] appears to be very characteristic for the Mediterranean Sea. On the Scandinavian coast, the Fucaceans have few species which occur in huge numbers of individuals; Fucus vesiculosus L. marks characteristically with its color the vegetation on the shore; this species and F. serratus L. extend into the Baltic; except of these and Halidrys, Halicoccus also occurs on the Swedish west coast; besides, on the Norwegian coast occurs Himanthalia lorea (L.) and Fucodium canaliculatum (L.), while on the coast of Finnmark a few arctic species are found too. In New Zealand and New Holland, numerous of the most characteristic species of these regions are found; with regard to the Fucaceae, we have observed that a number of characteristic species are distributed in the Southern Hemisphere while in the Northern Hemisphere an overwhelming number of individuals of a few species are found. On the seashore they occupy a characteristic position, mainly between ebb and flood; on our coasts occur on the splash zone and somewhat below; a few species, apparently from the Southern Hemisphere, belong to the deeper waters. (To this order belong many genera not found in the here examined regions.)

Order 5. Tilopteridales [as Tilopterideae]

[They ] comprise just one genus, Tilopteris, with one species T. mertensii (Eng. Bot.), that belongs to the European Atlantic coast, where it is found in England and France as well as on the Scandinavian west coast. Several species currently placed in Ectocarpus would probably be referred to this order after a revision.

Order 6. Vaucheriales [as Vaucherieae]
Order 7. Coleochaetales [as Coleochaetaceae]
Order 8. Oedogoniales [as Oedogoniaceae]

[These] occur largely in fresh water; a few exist also in the seas but rather prefer the brackish waters than a clear marine habitat. Along the Atlantic coasts of Europe and America, several species are known; algae belonging to these [orders] are also found in the Baltic.

Order 9. Phaeozoosporales [as Phaeozoosporeae]

Family 1. Laminariaceae [as Laminarieae]. As previously said, we encounter species of this group mainly in the cold seas, where they occur in high latitudes. They are found commonly in the Northern Hemisphere; even in the south a large number of species is found; some belong to the warmer seas where they occur sporadically. The plants of this group are generally larger than those mentioned so far, and within some genera from the Southern Hemisphere we found species that are enormously big, perhaps the largest within the plant kingdom[Footnote 8]. These large species of course occur in deep water - occasionally down to a couple of hundred feet; even our species do not thrive in shallow waters, as for example the Fucaceae generally; a few times they are found between ebb and flood. On the Atlantic coasts of Europe and North America, they form a wide band between ebb and down to 25 - 30 feet. Of the known species, a small part occurs in our region; in the Pacific, several characteristic [endemic] for that region species are found. They are, as we would expect, very few in the Mediterranean and the warmer parts of the Atlantic; on the Scandinavian west and north western coasts, several species are found. The most rich in species and for us important genus is Laminaria, whose several species occur in the North Atlantic; a couple of species are found in the Mediterranean, the only representatives of the entire family; a few Laminaria species extend down to the Sound; one or another occurs in large numbers as far north as to the Arctic Sea, where a few particular [endemic] species exist; none of the Atlantic species extends much to the south; in the Baltic, they are apparently missing, although a few drifting specimens have been found, probably passing via Oeresund. Laminaria saccharina (L.) has such a widespread distribution, that it is found on the coasts of all northern seas; strange is that on the west coast of North America, not one species of Laminaria exists. Of the characteristic genus Agarum, two species are found in the Atlantic and exclusively belong to North America; moreover, here belong the genera Alaria and Haligenia [Saccorhiza] each with one species in Norway. The genus Ecklonia, that primarily belongs to New Holland [Australia] and the Pacific Ocean, has also one member within the examined regions and this species occurs in the Canaries and the nearby coast of Africa. (Moreover, in the north and south parts of the Pacific Ocean, several remarkable genera exist, which only recently have been closely studied, mainly thanks to the magnificent English expeditions to these waters.)
Family 2. Sporochnaceae. The algae which belong to this family occur at places of the sea bottom where the Laminariaceae become rare and therefore are generally deep water plants; they are not found in the tide zone, except occasionally in some deep depressions. They are relatively few; within the examined regions just a couple are found. The main genus is Sporochnus, whose several species occur on the Atlantic coast of Europe and in the Mediterranean; so far none is found in North America, where the genus probably also has some species; on the coast of Bohus [Swedish west coast], one species, S. pedunculatus (Huds.), is found. The genus Carpomitra with several species from New Holland and New Zealand, also has one species in the regions here investigated.
Family 3. Cutleriaceae. A small group composed of a single genus, that has a few species, mainly found in the Mediterranean and Adriatic Seas. Cutleria multifida (Grev.) extends outside the Mediterranean to France and England, and also reaches the west coast of Sweden.
Family 4. Asperococcaceae include a few genera, that are spread throughout the regions examined here and even outside them; it appears that they thrive in temperate seas, although they are not lacking from the warm ones. Usually, they grow a bit below the water surface. Some species extend from the Atlantic to the North Sea and then to Skagerrack and Kattegatt as far as in the Baltic. Their distribution on the North American coast is similar to that on the European one, with the only difference being that fewer species are known in America; also in the Mediterranean exist a few species. Asperococcus has most of its species within the examined regions, partly in the North Sea and nearby waters and partly in the warmer parts of the Atlantic. Species of Stilophora, Striaria and Ralfsia, similarly exist even on the coast of Scandinavia; Stilophora has one species in the Southern Hemisphere, the other occur just within the regions examined. Two species of the genus Ralfsia are arctic and extend partly south in the Atlantic; a third species is found in the Gulf of Mexico.
Family 5. Chordariaceae are distributed within very different parts of the world but are apparently confined mainly to the temperate regions and particularly to the Northern Hemisphere; yet, they are not entirely absent from the cold regions. Like in some other related families, we found here many parasites [epiphytes]. A few American species have a highly restricted distribution and are only encountered in the Gulf of Mexico; on the Mediterranean coast, several for this region characteristic species are found such as two species of Leathesia, two species of Cladosiphon, and other. At the same time as some species are restricted to some areas, other are cosmpolitan like Leathesia tuberiformis [L. difformis] (Eng. Bot.), that occurs in both hemispheres; even Chordaria flagelliformis (Fl. Dan.) has an apparent widespread distribution. The members of this family do not generally grow in deep water; yet, they occur deeper than the rest of the family whose species, being parasites [epiphytes], are usually found near the water surface. Not few are found in Scandinavia; several extend into the Baltic, as far as Aaland and Roslagen, one up to Qvarken. Castagnea baltica Aresch. appears to be a unique species for the Baltic. The genus Chorda has a few species within the North Atlantic and a couple in other seas; a few species occur in the Baltic. Of another well-known genus, Elachista, that comprises small easily overlooked species, only one species from North America is reported; on the Scandinavian coast several are found; Elachista's species seem to be mainly distributed in Europe. Except of those mentioned, several other genera exist like Mesogloia and other which all have representatives in the Atlantic and in other seas.
Family 6. Sphacelariaceae are similar to the previous family's species as regards distribution and occurrence; yet, within this family we know relatively more species from the Southern Hemisphere. The species generally occur, as said above, not in deep water but close to the splash zone. Most of the species occurring in the Atlantic are found in Europe; just a few are known from North America; they have their greatest part of distribution in the middle and northern regions. The Sphacelariaceae are represented on the Scandinavian west and east coasts; in the Mediterranean and the Adriatic Seas, several species exist, partly unique to these seas and partly in common with other areas. Sphacelaria has members in almost all coasts within the various parts of the regions examined here. Chaetopteris has two species, one at the Cape of Good Hope and the other in Greenland and North Europe. The genus Cladostephus is represented by a couple of species on the American and European coasts, as well as in Scandinavia; it also has a few species outside the examined regions.
Family 7. Ectocarpaceae. Also the members of this group have their main distribution in temperate regions, but occur in colder seas too; they decrease in number towards the north and apparently the south; thus not a single species is, for example, reported from Central America or the corresponding part of Africa. As a result of being often sterile and morphologically similar to each other, members of this group are apparently not well-known, and are usually misidentified, and therefore we do not have an accurate knowledge of their distribution. In Europe it appears that they are most common on the coast of France and England, and in North America along the middle and northern states. In the Mediterranean and the Adriatic Seas, we also found a few species of this group; on the Swedish and Norwegian west coasts are they rather common; in the Baltic, a few are found and one of them reaches up to the Bay of Bothnia. They thrive best in shallow warm bays; some are parasites [epiphytes]. The main genus is Ectocarpus whose species occur both on the European and American coasts; certain species are widely distributed, other occur within a restricted area, for example several species in England; Harvey has separated several unique species for the NE American coast, but for their species status he is not very certain. Several species of this genus exist on our coasts, some extent even into the Baltic. Myriotrichia has a couple of species mainly in the British Isles; Myrionema has most of its species in the North Sea.
Family 8. Punctariaceae comprise just a few genera whose species occur within the examined regions, mainly in the temperate part of both Europe's and America's coasts; we encounter one or another in the Mediterranean and a few more species on the Scandinavian west coast, where some extend into the Baltic; Punctaria plantaginea (Roth) thrives on smooth rocks, exposed to strong waves; P. latifolia (Grev.) and [P.] undulata (J. Ag.) are again only parasites [epiphytes]. Phyllitis [Petalonia] has a few species, one of which is also found in the Baltic. Padinella [Aglaozonia] that has one species on the Swedish west coast, grows mostly on shell bottoms.
Family 9. Desmarestiaceae. Some species grow close to the water level and among them we find one or another parasite [epiphyte]; other occur in deep water, between 20 and 100 feet or more; they usually grow in associations that compete out other plants, and form meadows on the sea bottom. Harvey cites that in deep, enclosed bays on the coast of North America, Desmarestia aculeata (L.) dominates over all other vegetation at about 30 feet depth [Footnote 9]. Certain [species] have a widespread distribution extending through the temperate and cold seas rather far to the north and to the south; other species are more locally occurring. Within the warm seas few are found and most of them belong to the temperate and cold seas. From the coast of North America just a couple of species are known, while in the Mediterranean none. In Scandinavia several [are known]; a few extend south to the Sound and one is also found in the Baltic. Desmarestia, which is the most rich in species genus belongs rather to the Indian and the Pacific Oceans, but also has a few species in the Atlantic and Scandinavia. Dichloria [Desmarestia viridis] occurs even in other seas, apart from most Atlantic coasts. Dictyosiphon that belongs to the cold seas has a few unique species in Scandinavia. Litosiphon also has some species; a couple of these are found in Scandinavia.

Order 10. Chlorozoosporales [as Chlorozoosporeae]

Family 1. Siphonaceae belong almost exclusively to the warm seas; therefore, within the examined regions they occur in the Mediterranean and on the coasts of SW Europe and Central America; few extend up to England and Scandinavia; not a single one occurs in the Baltic. The remarkable genus Caulerpa belongs to the tropical and subtropical seas, extending to the north with a few species in the Mediterranean and a few other to New Zealand in the Southern Hemisphere. They occur mostly in sand between high and low water level, but a few [species] are encountered below low water level; some are characteristic for particular sea shores, where they grow within a restricted area; other are widespread throughout the tropics; some species occur in Florida. Halimeda, that has a similar distribution, is restricted to the warm seas of both hemispheres; its species apparently thrive well in coral reefs; a few occur on the American coast. A similar distribution has Udotea and other genera. Of the genus Codium, several species are found on the coast of Europe; C. tomentosum (Huds.) has a very widespread distribution throughout the Pacific and the Atlantic Oceans; strange is that on the east coast of North America, it has only been found on a few places, while it is common in Europe and in the Pacific. The genus Bryopsis is apparently abundant in the Mediterranean; a few species are also found in the Adriatic Sea; as also a few occur along the European and American Atlantic coasts; one of them B. plumosa (Huds.) extends north to the Faeroes, to the south until New Zealand, and moreover it occurs in many places both in the Atlantic and in the Pacific Oceans.
Family 2. Dasycladaceae [as Dasycladeae] comprise just a few tropical genera; within the examined regions, a few species occur in the warmer parts of North America and one species is found in the Mediterranean. Apart from Cymopolia, Dasycladus and Acetabularia, that occur within the regions investigated, a few more genera that belong to this group are exclusively found in the Southern Hemisphere and in the Pacific Ocean.
Family 3. Valoniaceae [as Valonieae] is a group restricted to the tropics and the subtropics, and the few genera and species that occur in the area examined are known from the Mediterranean and Central America. As regards their growing place, it is similar to the previous group; they thrive in coral reefs between the surface and several feet depth. Of the genus Valonia, 4 species are found in the regions examined, and they belong to the Mediterranean and Adriatic Seas. Moreover, here belong a few other genera that have one or another species in North America.
Family 4. Ulvaceae occur mainly in the temperate zones, partly in the sea in both marine and brackish water, partly sometimes in fresh water and on humid soil. Species of some genera occur nearly in all regions. Some are widely spread, other restricted to a small area; thus, several species of Enteromorpha, Ulva and Monostroma are widely occurring within the examined regions, while other grow just in Flandern, England or in the Gulf of Mexico, a.s.o. Enteromorpha compressa (L.) occurs abundantly in the cold regions in both hemispheres to the Equator. Prasiola also has several species within the regions examined.
Family 5. Confervaceae [Cladophoraceae] comprise a large number of species that are widely distributed over the entire globe; most of them belong to the fresh water, but a few are also found in marine waters. When they occur in the sea, they thrive best in brackish water or in rock pools between ebb and flood; they are usually found near the water surface; yet, one or another grows in deep water. The species belonging here are distributed both in Europe and in America, in the Mediterranean and in the Baltic. Some of the species, like in the previous group, are widespread, other are restricted in a small area. Both of the two large genera, Cladophora and Conferva, are found within all regions examined here; both have several species in the Mediterranean and the Adriatic Seas. Hormotrichum [Ulothrix] and Rhizoclonium belong exclusively to the northern seas in Greenland and North Europe. Hormiscia [Urospora ?] has a couple of species on our coasts. Numerous of the here belonging fresh water species, are occasionally met with in bays where the water is slightly marine.

Order 11. Algae conjugatae virides

The members of this group are almost exclusively found in fresh water; occasionally in brackish water. To give an account of their distribution in the sea is therefore rather difficult, apparently since they are usually sterile and therefore nearly impossible to identify at the level of species.

Order 12. Diatomales [as Diatomaceae]

This order consists of those algae that are silicon-armed, microscopic, and distributed to all seas. On the sea shore, like in fresh water, we encounter numerous genera and species of this group; however, from the phytogeographical point of view, we pay less attention to them than to the macrophytic vegetation; but the Diatomaceae deserve our attention even in this respect; since they occur even in places where all other vegetation has disappeared. Through deep dredging and by similar ways, we collect from the sea bottom a large number of algae belonging to this group, together with small marine animals in mud. We still lack any proof of maximum depth where such Diatomaceae are not found, although we have dredged down to 14.000 feet. They occur in countless numbers in all seas.

[TAXA OF UNCERTAIN ORDINAL POSITION]
Rivularieae and Oscillatorieae

The species that belong to these groups are widespread all over the world under almost all different conditions, on humid soil, in fresh water and even in the sea. Some are attached forms, other are planktonic on the water surface. Numerous of these algae occur often in fresh water and occasionally even in marine water, growing on the surface and producing a shining color. Since the distribution of these groups is not well-known, it is not possible to give an account of the regions where the various species are found. From the Mediterranean, several unique species are described; similarly, we know of several [species] that are exclusively found in the British Isles or within a restricted area in North America, a.s.o. Calothrix scopulorum (Ag.) is common throughout the North Atlantic and its various bays; a few species of Lyngbya are found both in Europe and on the North American coast. Even in the Baltic occur some members of these groups.

[CHAPTER 4. CONCLUSIONS]

Since we know that in previous times, water occupied a much larger area on earth than it does now, we can conclude that the algae occurred in larger amounts than in our days. Although easily damaged, have they, as we would expect, left tracks after them in the oldest rich in fossil deposits, where we encounter forms that come close to the Fucaceans or other living forms. If not the first, the algae were surely among the first organisms that appeared on earth. In general, we have not taken into account the influence of the algae in the development of the present earth crust; only for the Diatoms, because of their large number and ability to persist, we have considered some influence in this matter; although microscopic they form unmistakable layers of considerable size. Recently, Mohr has advanced an opinion that should be here cited but not critically assessed. According to this hypothesis, the large deposits of mineral coal, that are spread over the world, would namely be the product of algae, that in this way would have considerably contributed to the formation of the earth crust. Among other reasons that he takes as support, he cites that we do not find entire layers of mineral coal with clear structure, but just spread rests of higher plants embedded in an amorphous mass; a similar product that we obtain in the dry distillation of mineral coal, like in the distillation of mixed seaweeds [Fucaceans]; [this product is] characterized by a strong percentage of ammonia that it colors the red litmus paper blue, while [on the other hand] using wood, grass or Fucaceans, that have been cleared from their animal epiphytes, we get an acid distillate; that mineral coal usually occurs over a widespread area in very thin layers, and that the algal vegetation in the sea is still capable for an ongoing mineralization.

[FOOTNOTES]

1. On the South American west coast, in Peru and Chile between the 10 and 20 south latitudes, we encounter numerous algae, e.g. Lessonia, Macrocystis, etc. that otherwise are characteristic of the Antarctic Ocean; the reason that they reach higher up towards the Equator, than anywhere else, is that the cold Polar Stream cools down much of the otherwise warm water of S. America.
[2. Apparently, this is the alga from Paros that Harvey described as Cryptonemia forbesii. The species was later considered to be a synonym of Neurocaulon foliosum (Meneghini) Kuetzing.]
[3. Aulin follows Oersted (1844) who first described the three algal zones (green, brown, and red algae) in Oeresund and also suggested a link between the various colors in the light spectrum and the apparent green-brown-red algal zonation.]
4. The data of this and the previous table are taken from Forchhammer's work about the seawater in 'Oversigt over det Kongl. Danske Vidensk. Selsk. Foerhandl. Dec. 1862'.
5. The data of this table are taken from Krok's thesis on the algal flora in the inner Baltic Sea and Bothnia Bay in 'Ofversigt af Kongl. Vetensk. Akad. Foerhandl. 1869'; all the analyses refer to surface water.
6. The data are taken from different Chemistry journals.
[7. It probably refers to the norterhmost record of A. fragilissima from North Carolina (see Hoyt, Marine algae of Beaufort: 526. 1920).]
8. As an example of their large number and enormous size, Hooker describes that during an expedition to the Pacific the captain of the ship, in spite of Hooker's directions, let the gathering of floating stem of such algae to use as fuel believing that the material was drifting.
9. Hooker has described a similar situation in a few other species from the Southern Hemisphere.

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