Eucheuma (PROSEA) - Revision history

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	{{PROSEAUpperbar}}		{{PROSEAUpperbar}}
	{{DISPLAYTITLE:''Eucheuma'' (PROSEA)}}		{{DISPLAYTITLE:''Eucheuma'' (PROSEA)}}
			[[File:Eucheuma PROSEA.TIF\|thumb\|''Eucheuma arnoldii'' - 1, habit; 2, portion of a branch; 3, transverse section of a thallus; 4, detail of transverse section of the cortical region of a thallus; 5, detail of transverse section of the cortical region of a thallus with a tetrasporangium. ''E. serra'' - 6, transverse section of a thallus; 7, detail of a longitudinal section of the medullar region of a thallus. ]]
	<big>''[[Eucheuma]]'' J. Agardh</big>		<big>''[[Eucheuma]]'' J. Agardh</big>
	__NOTOC__		__NOTOC__
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	* Hatta, A.M., 1992. Eucheuma arnoldii Weber-van Bosse (Gigartinales, Rhodophyta). Informasi penemuan pertama di perairan Kepulauan Kai Kecil - Maluku Tenggara [Eucheuma arnoldii Weber-van Bosse (Gigartinales, Rhodophyta). Information on the first finding in Kai Kecil Islands water - -Southeastern Maluku]. Perairan Maluku dan Sekitarnya 4: 1-9.		* Hatta, A.M., 1992. Eucheuma arnoldii Weber-van Bosse (Gigartinales, Rhodophyta). Informasi penemuan pertama di perairan Kepulauan Kai Kecil - Maluku Tenggara [Eucheuma arnoldii Weber-van Bosse (Gigartinales, Rhodophyta). Information on the first finding in Kai Kecil Islands water - -Southeastern Maluku]. Perairan Maluku dan Sekitarnya 4: 1-9.
	* Kawakubo, A., Makino, H., Ohnishi, J., Hirohara, H. & Hori, K., 1997. The marine red alga Eucheuma serra J. Agardh, a high yielding source of isolectins. Journal of Applied Phycology 9: 331-338.		* Kawakubo, A., Makino, H., Ohnishi, J., Hirohara, H. & Hori, K., 1997. The marine red alga Eucheuma serra J. Agardh, a high yielding source of isolectins. Journal of Applied Phycology 9: 331-338.

			== Sources of illustration ==

			Trono, G.C. & Ganzon-Fortes, E.T., 1988. Philippine seaweeds. National Bookstore, Manila, The Philippines. Fig. 109A, p. 155 (habit, portion of a branch of E. arnoldii); Xia, B. & Zhang, J., 1999. Flora algarum marinarum sinicarum, vol. 2, Rhodophyta, 5. Academiae Sinicae Edita, Beijing, China. Fig. 69, p. 119 (sections of E. arnoldii), Fig. 72, p. 123 (sections of E. serra). Redrawn and adapted by P. Verheij-Hayes.

	== Authors ==		== Authors ==

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	== Uses ==		== Uses ==

	Species of the ''Eucheuma'' sections ''Eucheuma'' ( ''E. denticulatum'' , ''E. serra'' ) and ''Anaxiferae'' ( ''E. arnoldii'' ) are good sources of iota carrageenan. It appears that the carrageenan from ''E. denticulatum'' is the most valuable to industry, since it becomes an ideal iota carrageenan upon alkali modification. It is used in industrial food and beauty aid products, in pet foods, in granulated or hydrated gel components in various formulations, or prepared as a stew mixed with vegetables. The algae are eaten fresh or blanched in boiling water and mixed with salad garnish. In Vietnam thalli of ''Betaphycus'' Doty ex P.C. Silva, ''Eucheuma'' , and ''Kappaphycus'' are used in traditional medicine to reduce the incidence of tumors, ulcers and headaches. They are also used as manure and fertilizer.		Species of the ''Eucheuma'' sections ''Eucheuma'' (''E. denticulatum'', ''E. serra'') and ''Anaxiferae'' (''E. arnoldii'') are good sources of iota carrageenan. It appears that the carrageenan from ''E. denticulatum'' is the most valuable to industry, since it becomes an ideal iota carrageenan upon alkali modification. It is used in industrial food and beauty aid products, in pet foods, in granulated or hydrated gel components in various formulations, or prepared as a stew mixed with vegetables. The algae are eaten fresh or blanched in boiling water and mixed with salad garnish. In Vietnam thalli of ''Betaphycus'' Doty ex P.C. Silva, ''Eucheuma'', and ''Kappaphycus'' are used in traditional medicine to reduce the incidence of tumors, ulcers and headaches. They are also used as manure and fertilizer.

	== Production and international trade ==		== Production and international trade ==

	Production and trade data on " ''Eucheuma'' " often apply to all Eucheumoid algae (thus on ''Betaphycus'' and ''Kappaphycus'' as well), to the group of carrageenan-producing seaweeds as a whole or even to all red seaweeds together. World production (wet weight) by phycoculture of all " ''Eucheuma'' " together in 1986 was 160 106 t. By 1994 this figure had been 384 980 t. Of these, Indonesia produced 77 462 t in 1986 and 115 000 t in 1994 (these data also include ''Gracilaria'' Grev. and ''Gelidiales'' ) (only for " ''Eucheuma spinosum'' " = ''E. denticulatum'' ). The Philippines probably produced 8173 t in 1986 and in 20 190 t in 1994. Production from natural populations of ''E. serra'' in 1984 in the Philippines was estimated to be 60 t (dry weight).		Production and trade data on "''Eucheuma''" often apply to all Eucheumoid algae (thus on ''Betaphycus'' and ''Kappaphycus'' as well), to the group of carrageenan-producing seaweeds as a whole or even to all red seaweeds together. World production (wet weight) by phycoculture of all "''Eucheuma''" together in 1986 was 160 106 t. By 1994 this figure had been 384 980 t. Of these, Indonesia produced 77 462 t in 1986 and 115 000 t in 1994 (these data also include ''Gracilaria'' Grev. and ''Gelidiales'') (only for "''Eucheuma spinosum''" = ''E. denticulatum''). The Philippines probably produced 8173 t in 1986 and in 20 190 t in 1994. Production from natural populations of ''E. serra'' in 1984 in the Philippines was estimated to be 60 t (dry weight).

	== Properties ==		== Properties ==
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	It has been established that both female gametophytes and tetrasporophytes of ''E. arnoldii'' contain iota carrageenan and no other carrageenans. Gel strength in carrageenan of both life stages is 280 g/cm<sup>2</sup>. The carrageenan from cystocarpic material contains 22% 3,6-anhydro-galactose ester, while that of tetrasporic plants amounts to 23%. Cystocarpic plant carrageenan contains 32% sulphates, and tetrasporic plant carrageenan has 31%.		It has been established that both female gametophytes and tetrasporophytes of ''E. arnoldii'' contain iota carrageenan and no other carrageenans. Gel strength in carrageenan of both life stages is 280 g/cm<sup>2</sup>. The carrageenan from cystocarpic material contains 22% 3,6-anhydro-galactose ester, while that of tetrasporic plants amounts to 23%. Cystocarpic plant carrageenan contains 32% sulphates, and tetrasporic plant carrageenan has 31%.

	Carrageenan from ''E. serra'' has not been available for extraction and descriptive analysis. However, infrared analysis has shown spectra very similar to those of ''E. denticulatum'' , while molecular data (rbcL sequences) show differences with ''E. denticulatum'' as well as similarities with that species. Thalli of ''E. serra'' (from Japan) give high yields of lectins, identified as at least two different isolectins. Their quantities greatly exceed the yields from other macroalgae or other marine organisms.		Carrageenan from ''E. serra'' has not been available for extraction and descriptive analysis. However, infrared analysis has shown spectra very similar to those of ''E. denticulatum'', while molecular data (rbcL sequences) show differences with ''E. denticulatum'' as well as similarities with that species. Thalli of ''E. serra'' (from Japan) give high yields of lectins, identified as at least two different isolectins. Their quantities greatly exceed the yields from other macroalgae or other marine organisms.

	== Description ==		== Description ==

	Plants with cylindrical to flattened, erect, bushy or prostrate, fleshy to cartilaginous thalli of large size reaching over 1 kg in biomass, producing determinate spines in pairs or whorls at apex or margins and ventral surface of branches. Branches arising through spines becoming indeterminate. Secondary spines produced irregularly or uniformly over the older surfaces; branch in cross-section composed of three tissues: cortex with radiating cellular filaments of small diameter, medulla of large thick-walled cells surrounding dense central core consisting of thick-walled rhizoidal hyphae. Thalli multiaxial filamentous becoming strongly pseudo-parenchymatous. Life cycle triphasic, diplo-haplontic and isomorphic. Tetrasporangia zonate and embedded in the cortex. Gametophytes dioecious, with cystocarps borne near tips of branchlets; spermatangia in surface sori.		*Plants with cylindrical to flattened, erect, bushy or prostrate, fleshy to cartilaginous thalli of large size reaching over 1 kg in biomass, producing determinate spines in pairs or whorls at apex or margins and ventral surface of branches.
			*Branches arising through spines becoming indeterminate.
			*Secondary spines produced irregularly or uniformly over the older surfaces; branch in cross-section composed of three tissues: cortex with radiating cellular filaments of small diameter, medulla of large thick-walled cells surrounding dense central core consisting of thick-walled rhizoidal hyphae.
			*Thalli multiaxial filamentous becoming strongly pseudo-parenchymatous.
			*Life cycle triphasic, diplo-haplontic and isomorphic.
			*Tetrasporangia zonate and embedded in the cortex.
			*Gametophytes dioecious, with cystocarps borne near tips of branchlets; spermatangia in surface sori.

	* ''E. arnoldii'' . Thalli forming thick clumps with many clavate branches with slightly acute apices, densely covered with simple or compound spinose tubercles forming verticils at distinct "nodes" separated by "internodes", verticils overlapping at distal portion of branches so obscuring verticillate arrangement; section of a branch revealing a medulla composed of large rounded cells interspersed with smaller ones; cortical cells very small, ovoid or elongated; central core not evident. This ''Eucheuma'' mimics the habit of the ''Acropora'' coral with which it is closely associated.

	* ''E. serra'' . Thalli prostrate, with a disc-like holdfast with many branches arising in an irregular and circular pattern, main axes terete in basal parts, compressed to flattened in middle to apical parts, dorsal and ventral sides differing in colour: dorsal parts milky white or milky yellow, occasionally with light red spots, ventral parts dark to light red. Sporophytes (with more terete branches and circular thorn-like protuberances) and gametophytes slightly differing in morphology: male gametophytes with mainly sagittate protuberances, female gametophytes having these also frequently on dorsal side of flattened thalli; protuberances may change into carpogonia. Medulla of axes and branches consisting of crowded rhizoid-shaped cells surrounded by a cortex of irregularly arranged thick-walled rounded cells and an outer cortex of small cells of epidermal structure.		''E. arnoldii''.
			*Thalli forming thick clumps with many clavate branches with slightly acute apices, densely covered with simple or compound spinose tubercles forming verticils at distinct "nodes" separated by "internodes", verticils overlapping at distal portion of branches so obscuring verticillate arrangement; section of a branch revealing a medulla composed of large rounded cells interspersed with smaller ones; cortical cells very small, ovoid or elongated; central core not evident.
			*This ''Eucheuma'' mimics the habit of the ''Acropora'' coral with which it is closely associated.


			''E. serra''.
			*Thalli prostrate, with a disc-like holdfast with many branches arising in an irregular and circular pattern, main axes terete in basal parts, compressed to flattened in middle to apical parts, dorsal and ventral sides differing in colour: dorsal parts milky white or milky yellow, occasionally with light red spots, ventral parts dark to light red.
			*Sporophytes (with more terete branches and circular thorn-like protuberances) and gametophytes slightly differing in morphology: male gametophytes with mainly sagittate protuberances, female gametophytes having these also frequently on dorsal side of flattened thalli; protuberances may change into carpogonia.
			*Medulla of axes and branches consisting of crowded rhizoid-shaped cells surrounded by a cortex of irregularly arranged thick-walled rounded cells and an outer cortex of small cells of epidermal structure.

	== Other botanical information ==		== Other botanical information ==

	The taxonomy of Eucheumoid algae has recently been reviewed. The new genera ''Betaphycus'' Doty ex P.C. Silva, in which several species of the section ''Gelatiliforma'' Doty & Norris are included, and ''Kappaphycus'' Doty, which was the ''Eucheuma'' section ''Cottoniformia'' Doty & Norris, have been separated from ''Eucheuma'' proper. Main characteristics used to distinguish the different species and genera of the Eucheumoids are the nature of the undamaged apical segment, the location of the cystocarp, the presence or absence of an axial core and the nature of the gel. Of the species that have remained in ''Eucheuma'' , ''E. arnoldii'' , which belongs to the ''Eucheuma'' section ''Anaxiferae'' Weber Bosse, has cylindrical branches producing compound spines arranged in whorls. Branches do not possess a cylindrical hyphal or rhizoidal core, cystocarps are borne on the main axes and the principal wall component is iota carrageenan. In ''E. denticulatum'' , which together with ''E. serra'' , belongs to the section ''Eucheuma'' , branches are cylindrical and spines are simple, regularly arranged in pairs or may form whorls. Cross-section of a branch shows a cylindrical axial core consisting of rhizoids, the cystocarps are borne on spinose laterals and the main polysaccharide component of the walls is iota carrageenan. The morphology of the ''Eucheuma/Betaphycus/Kappaphycus'' clade in a phylogenetic study inferred from molecular data (rbcL sequences) is well supported. Although three of the four Doty & Norris sections (and thus also the separate new genera) receive strong support, the remaining species within the genus ''Eucheuma'' do not form a natural group, nor does the section ''Eucheuma'' itself. Thus further taxonomic research is needed to elucidate the phylogeny of this group of carrageenophytes.		The taxonomy of Eucheumoid algae has recently been reviewed. The new genera ''Betaphycus'' Doty ex P.C. Silva, in which several species of the section ''Gelatiliforma'' Doty & Norris are included, and ''Kappaphycus'' Doty, which was the ''Eucheuma'' section ''Cottoniformia'' Doty & Norris, have been separated from ''Eucheuma'' proper. Main characteristics used to distinguish the different species and genera of the Eucheumoids are the nature of the undamaged apical segment, the location of the cystocarp, the presence or absence of an axial core and the nature of the gel. Of the species that have remained in ''Eucheuma'', ''E. arnoldii'', which belongs to the ''Eucheuma'' section ''Anaxiferae'' Weber Bosse, has cylindrical branches producing compound spines arranged in whorls. Branches do not possess a cylindrical hyphal or rhizoidal core, cystocarps are borne on the main axes and the principal wall component is iota carrageenan. In ''E. denticulatum'', which together with ''E. serra'', belongs to the section ''Eucheuma'', branches are cylindrical and spines are simple, regularly arranged in pairs or may form whorls. Cross-section of a branch shows a cylindrical axial core consisting of rhizoids, the cystocarps are borne on spinose laterals and the main polysaccharide component of the walls is iota carrageenan. The morphology of the ''Eucheuma/Betaphycus/Kappaphycus'' clade in a phylogenetic study inferred from molecular data (rbcL sequences) is well supported. Although three of the four Doty & Norris sections (and thus also the separate new genera) receive strong support, the remaining species within the genus ''Eucheuma'' do not form a natural group, nor does the section ''Eucheuma'' itself. Thus further taxonomic research is needed to elucidate the phylogeny of this group of carrageenophytes.

	The use of the name ''Eucheuma serra'' has given rise to many problems. The type material clearly belongs to a genuine ''Eucheuma'' sp., containing iota carrageenan. However, it has been identified as " ''Eucheuma gelatinae'' " (= ''Betaphycus gelatinus'' ), which contains beta carrageenan, and also as " ''Eucheuma edule'' ", which might belong to the genus ''Kappaphycus'' .		The use of the name ''Eucheuma serra'' has given rise to many problems. The type material clearly belongs to a genuine ''Eucheuma'' sp., containing iota carrageenan. However, it has been identified as "''Eucheuma gelatinae''" (= ''Betaphycus gelatinus''), which contains beta carrageenan, and also as "''Eucheuma edule''", which might belong to the genus ''Kappaphycus''.

	== Ecology ==		== Ecology ==
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	''E. arnoldii'' is commonly found growing on dead coral fragments on platforms, solid coral pavements, coral rubble, algal limestone and living coral. It is generally associated with branching coral colonies and is quite limited in its vertical distribution: at low intertidal to shallow subtidal zones about 1.25 m above the lowest tide level to about 1.2 m below mean low water. It is usually absent in habitats where conditions permit sand deposition. Its habitat is generally influenced by swift current and silt-free water and the alga is present under these conditions throughout the year.		''E. arnoldii'' is commonly found growing on dead coral fragments on platforms, solid coral pavements, coral rubble, algal limestone and living coral. It is generally associated with branching coral colonies and is quite limited in its vertical distribution: at low intertidal to shallow subtidal zones about 1.25 m above the lowest tide level to about 1.2 m below mean low water. It is usually absent in habitats where conditions permit sand deposition. Its habitat is generally influenced by swift current and silt-free water and the alga is present under these conditions throughout the year.

	Because of its sprawling and closely adhering habit it is often difficult to detect specimens of ''E. serra'' , especially when they grow mixed with turf-forming algae. It grows on rocks and corals and occurs in intertidal pools, where it can even be exposed to the air at low tide, but also at depths up to 20 m. It is especially found in locations with clear water and heavy surf or on walls of channels with rather strong currents.		Because of its sprawling and closely adhering habit it is often difficult to detect specimens of ''E. serra'', especially when they grow mixed with turf-forming algae. It grows on rocks and corals and occurs in intertidal pools, where it can even be exposed to the air at low tide, but also at depths up to 20 m. It is especially found in locations with clear water and heavy surf or on walls of channels with rather strong currents.

	== Propagation and planting ==		== Propagation and planting ==
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	== Prospects ==		== Prospects ==

	On average, the world market for carrageenans has maintained a steady annual growth of 10%. In the Philippines, however, the annual growth during the period 1993-1997 has ranged between 20-30%. This high growth rate is reflected in the demand for an additional 10 000 t of dried seaweeds by the carrageenan processors. The continuing discovery of new industrial uses of carrageenan will lead to an increasing demand for supplies of raw material. Thus the prospects for farming carrageenophytes are bright. ''E. arnoldii'' , although presently not used in any form, is readily farmable in shallow, near-surface habitats in the vicinity of coral growth.		On average, the world market for carrageenans has maintained a steady annual growth of 10%. In the Philippines, however, the annual growth during the period 1993-1997 has ranged between 20-30%. This high growth rate is reflected in the demand for an additional 10 000 t of dried seaweeds by the carrageenan processors. The continuing discovery of new industrial uses of carrageenan will lead to an increasing demand for supplies of raw material. Thus the prospects for farming carrageenophytes are bright. ''E. arnoldii'', although presently not used in any form, is readily farmable in shallow, near-surface habitats in the vicinity of coral growth.

	== Literature ==		== Literature ==


	* Doty, M.S., 1986. The production and use of Eucheuma. In: Doty, M.S., Caddy, J.F. & Santelices, B. (Editors): Case studies of seven commercial seaweed resources. FAO Fishery Technology Paper 281: 123-161.		* Doty, M.S., 1986. The production and use of Eucheuma. In: Doty, M.S., Caddy, J.F. & Santelices, B. (Editors): Case studies of seven commercial seaweed resources. FAO Fishery Technology Paper 281: 123-161.
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	== Authors ==		== Authors ==

	G.C. Trono Jr & W.S. Atmadja		*G.C. Trono Jr & W.S. Atmadja


	[[Category:Algae (PROSEA)]]		[[Category:Algae (PROSEA)]]
	[[Category:PROSEA]]		[[Category:PROSEA]]

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	* ''Eucheuma cottonii'' Weber Bosse, see for ''[[Kappaphycus cottonii]]'' (Weber Bosse) Doty ex H.D. Nguyen & Q.N. Huynh in [[Kappaphycus (PROSEA)\|separate article on ''Kappaphycus'' Doty]].		* ''Eucheuma cottonii'' Weber Bosse, see for ''[[Kappaphycus cottonii]]'' (Weber Bosse) Doty ex H.D. Nguyen & Q.N. Huynh in [[Kappaphycus (PROSEA)\|separate article on ''Kappaphycus'' Doty]].

	* ''Eucheuma denticulatum'' (Burm.f.) Collins & Herv., see separate article.		* ''[[Eucheuma denticulatum]]'' (Burm.f.) Collins & Herv., see [[Eucheuma denticulatum (PROSEA)\|separate article]].

	* ''Eucheuma gelatinum'' (Esper) J. Agardh ('gelatinae'), see separate article on ''Betaphycus gelatinus'' (Esper) Doty ex P.C. Silva, Basson & R.L. Moe.		* ''Eucheuma gelatinum'' (Esper) J. Agardh ('gelatinae'), see [[Betaphycus gelatinus (PROSEA)\|separate article]] on ''[[Betaphycus gelatinus]]'' (Esper) Doty ex P.C. Silva, Basson & R.L. Moe.

	* ''Eucheuma inerme'' F. Schmitz, see for ''Kappaphycus inermis'' (F. Schmitz) Doty ex H.D. Nguyen & Q.N. Huynh in separate article on ''Kappaphycus'' Doty.		* ''Eucheuma inerme'' F. Schmitz, see for ''[[Kappaphycus inermis]]'' (F. Schmitz) Doty ex H.D. Nguyen & Q.N. Huynh in [[Kappaphycus (PROSEA)\|separate article on ''Kappaphycus'' Doty]].

	* ''Eucheuma serra'' (J. Agardh) J. Agardh, Öfvers. Kongl. Svenska Vetensk.-Akad. Förhandl. 4(1): 16 (1847), synonym: ''Sphaerococcus serra'' J. Agardh (1841).		* ''[[Eucheuma serra]]'' (J. Agardh) J. Agardh, Öfvers. Kongl. Svenska Vetensk.-Akad. Förhandl. 4(1): 16 (1847), synonym: ''Sphaerococcus serra'' J. Agardh (1841).

	* ''Eucheuma striatum'' Schmitz, see separate article on ''Kappaphycus striatus'' (F. Schmitz) Doty ex P.C. Silva.		* ''Eucheuma striatum'' Schmitz, see [[Kappaphycus striatus (PROSEA)\|separate article]] on ''[[Kappaphycus striatus]]'' (F. Schmitz) Doty ex P.C. Silva.

	== Vernacular names ==		== Vernacular names ==

	*Usually the vernacular names apply to all ''Eucheuma'' and ''Kappaphycus'' spp		*Usually the vernacular names apply to all ''Eucheuma'' and ''Kappaphycus'' spp.
	*Indonesia: agar-agar, agar besar (common names for all ''Eucheuma'' and ''Kappaphycus'' spp.), "spinosa" (common commercial name for all genuine ''Eucheuma'' spp., especially for ''E. denticulatum'' )		*Indonesia: agar-agar, agar besar (common names for all ''Eucheuma'' and ''Kappaphycus'' spp.), "spinosa" (common commercial name for all genuine ''Eucheuma'' spp., especially for ''E. denticulatum'')
	*Philippines: ruprupuuk (Ilocano), guso (Visayan), canot-canot (Ilocos Norte).		*Philippines: ruprupuuk (Ilocano), guso (Visayan), canot-canot (Ilocos Norte).

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	{{PROSEAUpperbar}}		{{PROSEAUpperbar}}
	{{DISPLAYTITLE:''Eucheuma J.'' (PROSEA)}}		{{DISPLAYTITLE:''Eucheuma'' (PROSEA)}}
	<big>''[[Eucheuma J.]]'' Agardh</big>		<big>''[[Eucheuma]]'' J. Agardh</big>
	__NOTOC__		__NOTOC__

	:Protologue: Öfvers. Kongl. Svenska Vetensk.-Akad. Förhandl. 4(1): 5-17 (1847).		:Protologue: Öfvers. Kongl. Svenska Vetensk.-Akad. Förhandl. 4(1): 5-17 (1847).

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	== Major species and synonyms ==		== Major species and synonyms ==

	* ''Eucheuma arnoldii'' Weber Bosse, Siboga Exped. Monogr. 59d: 421 (1928), synonym: ''E. cupressoideum'' Weber Bosse (1928).		* ''[[Eucheuma arnoldii]]'' Weber Bosse, Siboga Exped. Monogr. 59d: 421 (1928), synonym: ''E. cupressoideum'' Weber Bosse (1928).

	* ''Eucheuma cottonii'' Weber Bosse, see for ''Kappaphycus cottonii'' (Weber Bosse) Doty ex H.D. Nguyen & Q.N. Huynh in separate article on ''Kappaphycus'' Doty.		* ''Eucheuma cottonii'' Weber Bosse, see for ''[[Kappaphycus cottonii]]'' (Weber Bosse) Doty ex H.D. Nguyen & Q.N. Huynh in [[Kappaphycus (PROSEA)\|separate article on ''Kappaphycus'' Doty]].

	* ''Eucheuma denticulatum'' (Burm.f.) Collins & Herv., see separate article.		* ''Eucheuma denticulatum'' (Burm.f.) Collins & Herv., see separate article.

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Created page with "{{PROSEAUpperbar}} {{DISPLAYTITLE:''Eucheuma J.'' (PROSEA)}} <big>''Eucheuma J.'' Agardh</big> __NOTOC__ :Protologue: Öfvers. Kongl. Svenska Vetensk.-Akad. Förhandl. 4(..."

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{{PROSEAUpperbar}}
{{DISPLAYTITLE:''Eucheuma J.'' (PROSEA)}}
<big>''[[Eucheuma J.]]'' Agardh</big>
__NOTOC__

:Protologue: Öfvers. Kongl. Svenska Vetensk.-Akad. Förhandl. 4(1): 5-17 (1847).

:Family: Solieriaceae

:Chromosome number: 2''n''= possibly 20

== Major species and synonyms ==

* ''Eucheuma arnoldii'' Weber Bosse, Siboga Exped. Monogr. 59d: 421 (1928), synonym: ''E. cupressoideum'' Weber Bosse (1928).

* ''Eucheuma cottonii'' Weber Bosse, see for ''Kappaphycus cottonii'' (Weber Bosse) Doty ex H.D. Nguyen & Q.N. Huynh in separate article on ''Kappaphycus'' Doty.

* ''Eucheuma denticulatum'' (Burm.f.) Collins & Herv., see separate article.

* ''Eucheuma gelatinum'' (Esper) J. Agardh ('gelatinae'), see separate article on ''Betaphycus gelatinus'' (Esper) Doty ex P.C. Silva, Basson & R.L. Moe.

* ''Eucheuma inerme'' F. Schmitz, see for ''Kappaphycus inermis'' (F. Schmitz) Doty ex H.D. Nguyen & Q.N. Huynh in separate article on ''Kappaphycus'' Doty.

* ''Eucheuma serra'' (J. Agardh) J. Agardh, Öfvers. Kongl. Svenska Vetensk.-Akad. Förhandl. 4(1): 16 (1847), synonym: ''Sphaerococcus serra'' J. Agardh (1841).

* ''Eucheuma striatum'' Schmitz, see separate article on ''Kappaphycus striatus'' (F. Schmitz) Doty ex P.C. Silva.

== Vernacular names ==

*Usually the vernacular names apply to all ''Eucheuma'' and ''Kappaphycus'' spp
*Indonesia: agar-agar, agar besar (common names for all ''Eucheuma'' and ''Kappaphycus'' spp.), "spinosa" (common commercial name for all genuine ''Eucheuma'' spp., especially for ''E. denticulatum'' )
*Philippines: ruprupuuk (Ilocano), guso (Visayan), canot-canot (Ilocos Norte).

== Origin and geographic distribution ==

''Eucheuma'' is distributed throughout the tropics. Originally ''E. denticulatum'' and ''E. serra'' probably only occurred in the Indian Ocean and in South-East Asia. In most recent times especially ''E. denticulatum'' has been distributed to other areas by man. ''E. arnoldii'' has been recorded in the Indo-Malayan Archipelago in Indonesia and the Philippines, also from northern Queensland to the southern Ryukyu Islands and Taiwan. Farming trials with ''E. denticulatum'' and ''E. serra'' carried out before 1984 failed, but nowadays the former species is cultured in many localities.

== Uses ==

Species of the ''Eucheuma'' sections ''Eucheuma'' ( ''E. denticulatum'' , ''E. serra'' ) and ''Anaxiferae'' ( ''E. arnoldii'' ) are good sources of iota carrageenan. It appears that the carrageenan from ''E. denticulatum'' is the most valuable to industry, since it becomes an ideal iota carrageenan upon alkali modification. It is used in industrial food and beauty aid products, in pet foods, in granulated or hydrated gel components in various formulations, or prepared as a stew mixed with vegetables. The algae are eaten fresh or blanched in boiling water and mixed with salad garnish. In Vietnam thalli of ''Betaphycus'' Doty ex P.C. Silva, ''Eucheuma'' , and ''Kappaphycus'' are used in traditional medicine to reduce the incidence of tumors, ulcers and headaches. They are also used as manure and fertilizer.

== Production and international trade ==

Production and trade data on " ''Eucheuma'' " often apply to all Eucheumoid algae (thus on ''Betaphycus'' and ''Kappaphycus'' as well), to the group of carrageenan-producing seaweeds as a whole or even to all red seaweeds together. World production (wet weight) by phycoculture of all " ''Eucheuma'' " together in 1986 was 160 106 t. By 1994 this figure had been 384 980 t. Of these, Indonesia produced 77 462 t in 1986 and 115 000 t in 1994 (these data also include ''Gracilaria'' Grev. and ''Gelidiales'' ) (only for " ''Eucheuma spinosum'' " = ''E. denticulatum'' ). The Philippines probably produced 8173 t in 1986 and in 20 190 t in 1994. Production from natural populations of ''E. serra'' in 1984 in the Philippines was estimated to be 60 t (dry weight).

== Properties ==

It has been established that both female gametophytes and tetrasporophytes of ''E. arnoldii'' contain iota carrageenan and no other carrageenans. Gel strength in carrageenan of both life stages is 280 g/cm<sup>2</sup>. The carrageenan from cystocarpic material contains 22% 3,6-anhydro-galactose ester, while that of tetrasporic plants amounts to 23%. Cystocarpic plant carrageenan contains 32% sulphates, and tetrasporic plant carrageenan has 31%.

Carrageenan from ''E. serra'' has not been available for extraction and descriptive analysis. However, infrared analysis has shown spectra very similar to those of ''E. denticulatum'' , while molecular data (rbcL sequences) show differences with ''E. denticulatum'' as well as similarities with that species. Thalli of ''E. serra'' (from Japan) give high yields of lectins, identified as at least two different isolectins. Their quantities greatly exceed the yields from other macroalgae or other marine organisms.

== Description ==

Plants with cylindrical to flattened, erect, bushy or prostrate, fleshy to cartilaginous thalli of large size reaching over 1 kg in biomass, producing determinate spines in pairs or whorls at apex or margins and ventral surface of branches. Branches arising through spines becoming indeterminate. Secondary spines produced irregularly or uniformly over the older surfaces; branch in cross-section composed of three tissues: cortex with radiating cellular filaments of small diameter, medulla of large thick-walled cells surrounding dense central core consisting of thick-walled rhizoidal hyphae. Thalli multiaxial filamentous becoming strongly pseudo-parenchymatous. Life cycle triphasic, diplo-haplontic and isomorphic. Tetrasporangia zonate and embedded in the cortex. Gametophytes dioecious, with cystocarps borne near tips of branchlets; spermatangia in surface sori.

* ''E. arnoldii'' . Thalli forming thick clumps with many clavate branches with slightly acute apices, densely covered with simple or compound spinose tubercles forming verticils at distinct "nodes" separated by "internodes", verticils overlapping at distal portion of branches so obscuring verticillate arrangement; section of a branch revealing a medulla composed of large rounded cells interspersed with smaller ones; cortical cells very small, ovoid or elongated; central core not evident. This ''Eucheuma'' mimics the habit of the ''Acropora'' coral with which it is closely associated.

* ''E. serra'' . Thalli prostrate, with a disc-like holdfast with many branches arising in an irregular and circular pattern, main axes terete in basal parts, compressed to flattened in middle to apical parts, dorsal and ventral sides differing in colour: dorsal parts milky white or milky yellow, occasionally with light red spots, ventral parts dark to light red. Sporophytes (with more terete branches and circular thorn-like protuberances) and gametophytes slightly differing in morphology: male gametophytes with mainly sagittate protuberances, female gametophytes having these also frequently on dorsal side of flattened thalli; protuberances may change into carpogonia. Medulla of axes and branches consisting of crowded rhizoid-shaped cells surrounded by a cortex of irregularly arranged thick-walled rounded cells and an outer cortex of small cells of epidermal structure.

== Other botanical information ==

The taxonomy of Eucheumoid algae has recently been reviewed. The new genera ''Betaphycus'' Doty ex P.C. Silva, in which several species of the section ''Gelatiliforma'' Doty & Norris are included, and ''Kappaphycus'' Doty, which was the ''Eucheuma'' section ''Cottoniformia'' Doty & Norris, have been separated from ''Eucheuma'' proper. Main characteristics used to distinguish the different species and genera of the Eucheumoids are the nature of the undamaged apical segment, the location of the cystocarp, the presence or absence of an axial core and the nature of the gel. Of the species that have remained in ''Eucheuma'' , ''E. arnoldii'' , which belongs to the ''Eucheuma'' section ''Anaxiferae'' Weber Bosse, has cylindrical branches producing compound spines arranged in whorls. Branches do not possess a cylindrical hyphal or rhizoidal core, cystocarps are borne on the main axes and the principal wall component is iota carrageenan. In ''E. denticulatum'' , which together with ''E. serra'' , belongs to the section ''Eucheuma'' , branches are cylindrical and spines are simple, regularly arranged in pairs or may form whorls. Cross-section of a branch shows a cylindrical axial core consisting of rhizoids, the cystocarps are borne on spinose laterals and the main polysaccharide component of the walls is iota carrageenan. The morphology of the ''Eucheuma/Betaphycus/Kappaphycus'' clade in a phylogenetic study inferred from molecular data (rbcL sequences) is well supported. Although three of the four Doty & Norris sections (and thus also the separate new genera) receive strong support, the remaining species within the genus ''Eucheuma'' do not form a natural group, nor does the section ''Eucheuma'' itself. Thus further taxonomic research is needed to elucidate the phylogeny of this group of carrageenophytes.

The use of the name ''Eucheuma serra'' has given rise to many problems. The type material clearly belongs to a genuine ''Eucheuma'' sp., containing iota carrageenan. However, it has been identified as " ''Eucheuma gelatinae'' " (= ''Betaphycus gelatinus'' ), which contains beta carrageenan, and also as " ''Eucheuma edule'' ", which might belong to the genus ''Kappaphycus'' .

== Ecology ==

''E. arnoldii'' is commonly found growing on dead coral fragments on platforms, solid coral pavements, coral rubble, algal limestone and living coral. It is generally associated with branching coral colonies and is quite limited in its vertical distribution: at low intertidal to shallow subtidal zones about 1.25 m above the lowest tide level to about 1.2 m below mean low water. It is usually absent in habitats where conditions permit sand deposition. Its habitat is generally influenced by swift current and silt-free water and the alga is present under these conditions throughout the year.

Because of its sprawling and closely adhering habit it is often difficult to detect specimens of ''E. serra'' , especially when they grow mixed with turf-forming algae. It grows on rocks and corals and occurs in intertidal pools, where it can even be exposed to the air at low tide, but also at depths up to 20 m. It is especially found in locations with clear water and heavy surf or on walls of channels with rather strong currents.

== Propagation and planting ==

''Eucheuma'' is largely propagated by vegetative fragmentation.

== Diseases and pests ==

One of the major diseases in cultivated ''Eucheuma'' is "ice-ice" disease.

== Yield ==

Carrageenan yield in cystocarpic material of ''E. arnoldii'' is 53% and in tetrasporic material 47%.

== Prospects ==

On average, the world market for carrageenans has maintained a steady annual growth of 10%. In the Philippines, however, the annual growth during the period 1993-1997 has ranged between 20-30%. This high growth rate is reflected in the demand for an additional 10 000 t of dried seaweeds by the carrageenan processors. The continuing discovery of new industrial uses of carrageenan will lead to an increasing demand for supplies of raw material. Thus the prospects for farming carrageenophytes are bright. ''E. arnoldii'' , although presently not used in any form, is readily farmable in shallow, near-surface habitats in the vicinity of coral growth.

== Literature ==

* Doty, M.S., 1986. The production and use of Eucheuma. In: Doty, M.S., Caddy, J.F. & Santelices, B. (Editors): Case studies of seven commercial seaweed resources. FAO Fishery Technology Paper 281: 123-161.
* Doty, M.S., 1988. Prodromus ad systematica Eucheumatoideorum: a tribe of commercial seaweeds related to Eucheuma (Solieriaceae, Gigartinales). In: Abbott, I.A. (Editor): Taxonomy of economic seaweeds 2. pp. 159-208.
* Doty, M.S. & Norris, J.N., 1985. Eucheuma species (Solieriaceae, Rhodophyta) that are major sources of carrageenan. In: Abbott, I.A. & Norris, J.N. (Editors): Taxonomy of economic seaweeds 1. pp. 47-65.
* Fredericq, S., Freshwater, D.W. & Hommersand, M.H., 1999. Observations on the phylogenetic systematics and biogeography of the Solieriaceae (Gigartinales, Rhodophyta) inferred from rbcL sequences and morphological evidence. Hydrobiologia 398/399: 25-38.
* Hatta, A.M., 1992. Eucheuma arnoldii Weber-van Bosse (Gigartinales, Rhodophyta). Informasi penemuan pertama di perairan Kepulauan Kai Kecil - Maluku Tenggara [Eucheuma arnoldii Weber-van Bosse (Gigartinales, Rhodophyta). Information on the first finding in Kai Kecil Islands water - -Southeastern Maluku]. Perairan Maluku dan Sekitarnya 4: 1-9.
* Kawakubo, A., Makino, H., Ohnishi, J., Hirohara, H. & Hori, K., 1997. The marine red alga Eucheuma serra J. Agardh, a high yielding source of isolectins. Journal of Applied Phycology 9: 331-338.

== Authors ==

G.C. Trono Jr & W.S. Atmadja

[[Category:Algae (PROSEA)]]
[[Category:PROSEA]]