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Volume 81, 1953
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The Chemical Composition of the two New Zealand Species of Durvillea.

*

[Read by title before Otago Branch on Tuesday, June 9, 1953; received by Editor June 22, 1953.]

Abstract

Plants of Durvillea antarctica (Chamisso) Hariot and of Durvillea willana, Lindauer collected at the same season from the same locality, showed variations in the percentages of dry matter, mineral ash, crude proteins, mannitol and alginic acid both between different parts of the same plants and between comparable morphological regions at different stages of development. In most cases these variations are similar to those seen in other species of brown algae which have been investigated.

Introduction

Little is known about the chemical composition of the two New Zealand species of Durvillea apart from Aston's (1916) determination of potash salts in D. antarctica as 1.75 per cent. of the dry weight, and Hercus and Aitken's (1938) estimation of iodine in the same species as 0.0023 per cent. of the dry weight. There is no quantitive information concerning the organic constituents of either species. Marini-Bettolo (1948) investigated the alginic acid content of D. antarctica growing off the coast of Chile, but his estimate is of little value for comparative purposes as it is calculated as a percentage of total polysaccharide, a basis not used by other workers.

Since the pioneer work of Stanford (1883, 1884a, 1884b, 1886) many analyses of the organic constituents of the brown seaweeds have been carried out, largely with a view to their utilisation in industry. The results of the early determinations were often inconsistent, probably due, as Sauvageau (1918) pointed out to inadequate description of the material selected for analysis and insufficient consideration being given to the season. Lapique (1919) made the first systematic investigation into seasonal variations in chemical composition, and more recently Black (1948, 1949, 1950a) has demonstrated that many British species show considerable seasonal variation in dry weight and in chemical composition. Moss has also demonstrated further sources of variation. She demonstrated (1948, 1950) that in Fucus vesiculosus L variation occurred between different parts of the same plant and also between comparable parts of plants collected from different localities. This latter variation was characteristic of the permanent parts of the plants and did not extend to the short lived receptacles. Finally it was demonstrated that Himanthalia elongata (L) S. F. Gray showed variation between comparable regions at different developmental stages collected from the same locality at the same time (Moss, 1952).

[Footnote] * Collections of material and dry weight determinations were made by the second author during the tenure of the Johnstone and Florence Stoney Studentship of the British Federation of University Women for 1949; chemical analyses were carried out by the first author.

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Material and Methods

The present investigation was undertaken to investigate the variation in the chemical composition of Durvillea antarctica (Chamisso) Hariot and of D. willana Lindaner at different stages of development. In order to eliminate any possible variation due to season or locality the plants were collected from St. Clair, Dunedin, in late May and early June, when all stages of development could be collected at the same time. The short period of intertidal exposure, however, made it necessary to collect over the period of two spring tides separated by an interval of a fortnight.

Plants of both species were sorted into the four following categories for analysis:—

I.

Plants less than two inches long.

II.

Plants from two to twelve inches long.

III.

Immature plants about six feet long and showing signs of conceptacle development.

IV.

Plants with mature conceptacles.

The plants in each category were subdivided into disc, stipe and lamina for separate analysis. In categories III and IV the sterile basal “palms” were analysed separately from the fertile portions which were further separated into male and female fronds. A complete set of samples was obtained only for D. antarctica as the deeper water habitat of D. willana made it impossible to collect all samples on these tides.

All the samples were dried, ground and analysed, using the methods developed by the Institute of Seaweed Research (Black, 1948; Cameron, Ross and Percival, 1948).

Dry Weight

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Table I.—Dry Weight of 2 species of Durvillea expressed as a percentage of the fresh weight.
I II III IV
D. antarc. D. willana D. antarc. D. willana D. antarc. D. willana D. antarc. D. willana
Disc 20.2 19.2 21.1 21.8 23.1
Stipe 20.2 15.8 15.9 17.8 17.5 17.7 17.1
“Palm” 16.5 17.3
Lamina Male 18.1 16.3 22.6 21.1 21.4 23 0 27.2
Female 21.6 21.4 22.0 27.1

In D. antarctica, at all stages of development there is a decrease in dry weight from disc to lamina, as might be expected, for the lamina contains the young and actively growing tissues. A similar decrease from base to tip is seen in Fucus vesiculosus (Moss, 1948). In older plants, the sterile basal “palm” has a value comparable with that of the stipe, which it resembles in anatomical structure. The dry weight of the fertile lamina is high, the increase which here accompanies the development of the conceptacles being in marked contrast with the condition found in Fucus vesiculosus (Moss, 1950) and Himanthalia elongata (Moss, 1952). The explanation of this is probably due to the different nature of the conceptacle bearing regions. In the two British species the conceptacles occur on special receptacles which develop behind the young apices and mature in the space of several months. Intercellular mucilage accumulates in the medulla of these receptacles and retains a large amount of water, thus accounting for the low dry

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weight of the fertile regions of these species. In Durvillea, on the other hand, conceptacles are not produced until the plant is several years old, and are then developed on the mature regions of the lamina in which the dry weight is increasing. Further, the conceptacles of Durvillea are relatively much smaller—300 to a square inch were counted in a mature plant of D. antarctica—and they extend only a small way into the cortex.

Mineral Ash

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Table II.—Mineral Ash in 2 Species of Durvillea expressed as a pcrcentage of the dry weight.
I II III IV
D. antarc D. willana D. antarc D. willana D. antarc D. willana D. antarc. D. willana
Disc 20.3 26.2 22.1 21.4
Stipe 31 8 29.0 29 7 26.4 29.6 32.4
“Palm” 19.4 26.4
Lamina Male 29.0 24 4 24.7 27.4 21.4 22.7 23.0
Female 26.5 21.4 20.1 20.5

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Table III.—Mineral Ash in 2 Species of Durvillea expressed as a percentage of the fresh weight.
I II III IV
D. antarc. D. willana D. antarc. D. willana D. antarc. D. willana D. antarc. D. willana
Disc 4.1 5.0 4.8 4.9
Stipe 5.0 4.6 5.3 4.6 5.2 5.5
“Palm” 3 2 4.7
Lamina Male 5 3 3.7 5.6 5.9 4.6 5 2 6.3
Female 5.7 4 6 4.4 5 6

At all stages of development of both species the greatest percentage of mineral ash is found in the stipe.

A decrease in the ash content of disc and stipe, and most marked of all, in the sterile “palm” of the frond, coincides with the increased accumulation of minerals in the developing fertile regions of the plants. In the oldest plants of D. antarctica a decrease in ash constituents occurs in the fertile regions, while at the same time ash increases in the sterile “palm”. Maximum ash content in the lamina at the time of reproduction agrees with previous findings for F. vesiculosus (Moss, 1950) and Himanthalia elongata (Moss, 1952).

Crude Proteins

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Table IV.—Crude Proteins in 2 Species of Durvillea expressed as a percentage of the dry weight.
I II III IV
D. antarc. D. willana D. antarc. D. willana D. antarc D. willana D. antarc. D. willana
Disc 7.1 11 5 9.4 8.6
Stipe 7 2 6.1 5.1 6.4 7.1 6.4
“Palm” 5.1 4.3
Lamina Male 8.3 8.3 7.3 6.0 6.7 5.4 4.9
Female 5.0 6.7 4 3 5.2
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Table V.—Crude Proteins in 2 Species of Durvillea, expressed as a percentage of the fresh weight.
I II III IV
D. antarc. D. willana D. antarc. D. willana D. antarc. D. willana D. antarc D. willana
Disc 1.4 2.2 2.0 2.0
Stipe 1.1 0.9 0.9 1.1 1.3 1.1
“Palm” 0 8 0 7
Lamina Male 1.5 1 3 1.6 1.3 1.4 1.2 1.3
Female 1 1 1 4 0.9 1.4

On the whole the percentage protein present is low. There is a slight decrease in crude proteins when the lamina becomes fertile, perhaps comparable with that in Fucus vesiculsus. Most noticeable are the higher values found in the discs, similar to those found by Black (1950) in the haptera of Laminaria.

Mannitol

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Table VI.—Mannitol in 2 Species of Duvillea, expressed as a percentage of the dry weight.
I II III IV
D. antarc. D. willana D. antarc. D. willana D. antarc. D. willana D. antarc D. willana
Disc 7 8 10 6 12.3 12.3
Stipe 11 9 8.5 13.3 13.3
“Palm” 11 3 8 9
Lamina Male 6 7 8 0 11.4 8.6 6.9 10.9
Female 9.9 6 6 6.3

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Table VII.—Mannitol in 2 Species of Durvillea, expressed as a percentage of the fresh weight.
I II III IV
D. antarc. D. willana D. antarc. D. willana D. antarc. D. willana D. antarc D. willana
Disc 1.6 2 0 2.7 2.8
Stipe 1.9 1.4 2.4 2.4
“Palm” 1 9 1 5
Lamina Male 1.2 1.2 2.6 1.9 1.6 2.9
Female 2.1 1.5 1.7

Throughout the development of both disc and stipe a gradual increase in mannitol occurs, and it is always higher in these regions of the plant than in the lamina.

On a dry weight basis, male and female reproductive regions of the fronds have lower values than the sterile regions of the same fronds, as in Fucus vesiculosus (Moss, 1951).

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Alginic Acid.

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Table VIII.—Alginic Acid in 2 Species of Durvillea, expressed as a percentage of the dry weight.
I II III IV
D. antarc. D. willana D. antarc. D. willana D. antarc. D. willana D. antarc D. willana
Disc 33.0 24.7 20.6 26.0
Stipe 38.0 40.5 36 0 35 9 39 8 37.0
“Palm” 40 4 41.6
Lamina Male 43 5 38 6 36.9 40.6 39.0 36.0 44.8
Female 39.7 39.0 32.0 37.1

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Table IX—Alginic Acid in 2 Species of Durvillea, expressed as a percentage of the fresh weight.
I II III IV
D. antarc. D. willana D. antarc. D. willana D. antarc. D. willana D. antarc D. willana
Disc 6.7 4.7 4.5 6.0
Stipe 6.0 6.4 6.4 6.3 7 0 6 3
“Palm” 6 7 7.2
Lamina Male 7.9 5 9 8.4 8 8 8.3 8.3 12.2
Female 8.6 8.3 7.0 10.1

The amount of alginic acid shows greater variations between different regions of the plant in both species than does any other organic constituent determined.

The disc always shows a lower percentage alginic acid than either the stipe or lamina. In the stipe the alginic acid remains relatively constant throughout the life of the plant, but the lamina of sporelings has a higher percentage of alginic acid, and the value decreases as the lamina ages. This decrease is more pronounced in the fertile portions, the sterile regions maintaining a value comparable with that of the stipe. This may be due to the increased production of secondary cortex by the meristoderm as the plant ages—cf. the lower values in the disc which is composed largely of rows of secondary cortical cells (Naylor, 1953). The slightly lower values consistently found in D. willana may also be of interest in this respect, as this species is characterised by a greater development of secondary cortex at all levels than is D. artarctica (Naylor, 1953).

The values obtained for alginic acid are high, and approximate to those in British species of Laminaria (Black, 1950) rather than to the lower values in the Fucales (Black, 1949). D. willana is infra-littoral, and D. antarctica, although not infra-littoral, occurs at the lowest limit of the littoral belt, so possibly these higher percentages of alginic acid are features of seaweeds of the infra-littoral belt.

Discussion

Determinations of some of the major chemical constituents of D. antarctica and of D. willana show a fairly close agreement between the species. Black (1950b) has shown how depth of immersion, especially during the summer months, may appreciably affect the chemical composition of the three British species of Laminaria Unfortunately the samples collected for the present investigation were too incomplete to judge whether any of the differences between the two species might be due to such a factor.

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As in other species investigated, variation in chemical composition were found at different levels in the plant, most of which were similar to those already demonstrated in Fucus vesiculosus and Laminaria. There were also changes during the development of the plants, and these also showed trends similar to those seen in Fucus vesiculosus and in Himanthalia elongata.

Such variations in plants collected at the same time from the same habitat also emphasise the importance of providing precise information concerning the material under investigation.

Literature Cited

Aston, B. C., 1916. Potash in Agriculture II. N.Z. Journ. Agric., 13, 446.

Black, W. A. P., 1948. The seasonal variation in chemical composition of some of the sub-littoral seaweeds common to Scotland. Journ. Soc. Chem. Ind., 61, 165.

— 1949. Seasonal variation in chemical composition of some of the littoral weeds common to Scotland. Part II. Fucus serratus, Fucus vesiculosus and Pelvetia canaliculata. Ibid., 68, 183.

— 1950a. The seasonal variation in weight and chemical composition of the common British Laminariaceae. Journ. Mar. Biol. Assoc. U.K., 29, 45.

— 1950b. The effect of the depth of immersion on the chemical constitution of some of the sub-littoral seaweeds common to Scotland. Journ. Soc. Chem. Ind., 69, 161.

Cameron, M. C., Ross, A. G. and Percival, E. G. V., 1948. Methods of the routine estimation of mannitol, alginic acid and combined fucose in seaweeds. Ibid., 67, 161.

Hercus, C. E. and Aitken, H. H. A., 1938. Miscellaneous studies on the iodine and goitre problem in New Zealand. Journ. Hygiene. 33, 55.

Lapique, L., 1919. Seasonal variation in the chemical composition of the marine algae. C. R. Acad. Sci., Paris, 169, 1426.

Marini-Bettolo, G. B., 1948. Ricerche chimiche sulle alghe del Chile. Nota I. I. polisaccaridi della Durvillea utilis. Ann. Chim. Applicata, 38, 294.

Moss, B. L., 1948. On the structure and chemical composition of Fucus vesiculosus from three Scottish localities. Ann. Bot. N. S., 12, 267.

— 1950. The anatomical structure and chemical composition of receptacles of Fucus vesiculosus from three contrasting habitats. Ibid., 14, 396.

— 1952. Variations in chemical composition during the development of Himanthalia elongata (L) S. F. Gray. Journ. Mar. Biol. Assoc. U.K., 31, 29.

Naylor, M., 1953. The New Zealand species of Durvillea. Trans. Roy. Soc. N.Z., 80, 277.

Sauvageau, C., 1918. Re′flexions sur les analyses chimiques d'algues marines. Rev. Gen. des Sci., 19.

Stanford, E. C. C., 1883. On algin: a new substance obtained from some of the common species of marine algae. Chem. News, 47, 254 and 267.

— 1884a. On algin. Journ. Soc. Chem. Ind., 3, 297.

— 1884b. The economic applications of seaweed. Journ. Soc. Arts, London, 32, 717.

— 1886. On alginic acid and its compounds. Journ. Soc. Chem. Ind., 5, 218.