Furcellaria is a genus of red algae. It is a monotypic genus, the only species being Furcellaria lumbricalis, which has commercial importance as a raw material for carrageenan production. It is mainly harvested from the waters of Denmark and Canada.
It grows on submerged rocks to a depth of about , but it can also grow in large floating mats, which are easier to harvest.
F. lumbricalis is also an important habitat-forming seaweed, forming underwater "belts" often just below those of bladderwrack. These belts provide spawning habitat for many fish species, and for this reason some governments place regulations on the harvesting of this seaweed.
Description
Furcellaria lumbricalis is a common red
Macroalgae species.
[Rayment, W.J. 2008. Furcellaria lumbricalis A red seaweed. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, on-line. Plymouth: Marine Biological Association of the United Kingdom. cited.] The species has two different ecotypes – attached and loose-lying (drifting) thallus forms (previously also known as
Furcellaria fastigiata f. aegagropila). Attached
F. lumbricalis is widely distributed sublittoral species on both sides of the North Atlantic.
[P. Kersen, Red Seaweeds Furcellaria lumbricalis and Coccotylus truncatus: Community Structure, Dynamics and Growth in the Northern Baltic Sea, Tallinn: Tallinn University, 2013.]
[R. Tuvikene, K. Truus, M. Robal, O. Volobujeva, E. Melikov, T. Pehk, A. Kollist, T. Kailas and M. Vaher, "The extraction, structure, and gelling properties of hybrid galactan from the red alga Furcellaria lumbricalis (Baltic Sea, Estonia)," Journal of Applied Phycology, pp. 51-63, 2010.]
The attached form grows typically as an epilith on stable hard substrates such as stony bottoms, boulder fields and rocks. It is a perennial macroalgae with a life-span up to 10 years, that tolerates salinities down to 3.6 psu. Although the species has been reported to grow up to 30 m deep, the main occurrence is between 8−12 m.
F. lumbricalis forms monotypic dense meadows in the central and northern Baltic Sea, where most of the other perennial red algae are not able to sustain the low salinity.
[HELCOM, "Furcellaria lumbricalis," 2013.]
Over the last half a century, communities of loose-lying F. lumbricalis in Kattegat, Denmark and Puck Lagoon, Poland have been disappeared due to overharvesting or eutrophication. In other places, the species is too sparsely distributed, making it incompatible for industrial practices. The drifting forms of F. lumbricalis and Coccotylus truncatus form a loose-lying algal stratum in Kassari bay, which is the most abundant community in the Baltic Sea. Because of its unique location and relatively high biomass, it has been used for furcellaran production since the mid 1960s and is an example of a sustainable bioresource utilization.[R. Tuvikene, K. Truus, M. Vaher, T. Kailas, G. Martin and P. Kersen, "Extraction and quantification of hybrid carrageenans from the biomass of the red algae Furcellaria lumbricalis and Coccotylus truncatus," Proceedings of the Estonian Academy of Sciences. Chemistry, pp. 40-53, 2006.]
The stratum's (average depth 7.5 m) density seems to differ greatly year to year (Table 1), ranging between 100 000 to 200 000 tons by wet weight. The change could be as a result of meteorological factors such as harsher winters or hotter summers, storms and the like.
Distribution
It is commonly found near the coasts of Eastern Canada,
British Isles and is the only widely distributed red algal species in the
Baltic Sea.
[T. E. Furia, "Furcellaran," in CRC Handbook of Food Additives, Second Edition, CRC Press, 1972, p. 311.] Found also in Northern Russia, Iceland, Faeroes and Norway to France.
[Dixon, P.S. and Irvine, L.M. 1977 Seaweeds of the British Isles Volume 1 Rhodophyta Part 1 Introduction, Nemaliales, Gigartinales. British Museum (Natural History). .]
Quantitative characteristics
Key quantitative characteristics of the loose-lying
Furcellaria-Coccotylus community in the Kassari Bay monitored by the Estonian Marine Institute.
[T. Paalme, "Kassari lahe tööndusliku punavetikavaru uuringud," TÜ Eesti Mereinstituut, Tallinn.]
Biomolecules from Furcellaria lumbricalis
Due to the polysaccharides in the cell walls,
F. lumbricalis is grouped with other commercially important carrageenophytes (red algae that produce
).
From
F. lumbricalis a
polysaccharide called furcellaran (hybrid β/κ-carrageenan) can be extracted. Furcellaran is non-stoichometrically undersulphated κ-carrageenan, where every 3rd or 4th 3-linked-β-
galactose monomer possesses a sulphate ester group at the 4th carbon position. For comparison, an ideal κ-carrageenan molecule would have a sulphate ester group at the 4th carbon in every 3-linked-β-galactose monomer. Furcellaran’s physical properties (gel strengths, gelling and melting temperatures) are similar to κ-carrageenan.
[R. Tuvikene, K. Truus, M. Vaher, T. Kailas, G. Martin and P. Kersen, "Extraction and quantification of hybrid carrageenans from the biomass of the red algae Furcellaria lumbricalis and Coccotylus truncatus," pp. 40-53, 2005]
Carrageenans found within certain seaweed species and locations are not universally similar, samples collected from different locations may have variable sulphation degrees.
Studies show that total extraction yield is up to 31% (dry weight).
However, in its unattached state, it is noted that polysaccharide yields are lower and some consider this to be the result of narrower thallus filaments giving way to a smaller amount of
galactan present.
Also, can be extracted from F. lumbricalis, from which the R-phycoerythrin yield is ~0.1% by dry weight.[M. Saluri, M. Kaldmäe and R. Tuvikene, "Extraction and quantification of phycobiliproteins from the red alga," Algal Research, vol. 37, pp. 115-123, 2019.]
Industrial use
Cations need to be present to form a strong
gel in an aqueous solution. It is a process that depends on the nature of the polysaccharide, polymer concentration, temperature and the ions. K
+, Rb
+ and Cs
+ ions produce strong κ-carrageenan and furcellaran gels, whereas Ca
2+ ions aid the gelling of ι-carrageenan (extracted from the cell walls of
C. truncatus). An initial coil-to-helix transition has been observed as the primary change in the gelling process, which is followed by the aggregation of these helices to form a gel. These sorts of gels are
thermoreversible, meaning that they gel when temperature drops and melt when the gel is heated.
The food industry depends on this natural component and are used to add texture as a way of additive to certain foods candies, ice cream and puddings. When carrageenans are used as food additives in the EU, they are referred to as
E number (E407a is a Processed
Eucheuma seaweed, where most impurities are washed out, but most of the cellulose remains). Additionally, it can be found in the pharmaceutical and cosmetic industries in which it's included to things such as foams and soluble tablets. Furcellaran can also be used instead of κ-carrageenan as a beer
wort fining agent.
[M. Saluri, M. Robal and R. Tuvikene, "Hybrid carrageenans as beer wort fining agents," Food Hydrocolloids, vol. 86, pp. 26-33, 2019.]
[R. L. Whistler, "Furcellaran," in Industrial Gums: Polysaccharides and Their Derivates, New York, Academic Press INC, 1973, pp. 133-134.]
Similar species
Polyides rotunda is similar but can be distinguished by having a discoid holdfast.
[Bunker, F.StP.D., Brodie, J.A., Maggs, C.A. and Bunker, A.R.2017 Seaweeds of Britain and Ireland. Second Edition Wild Nature Press Plymouth. .]
