Prospects for the cultivation of economically important carrageenophytes in Southeast Mexico

Carrageenan, a hydrocolloid used in the food and pharmaceutical industry mainly as a thickener and stabilizer, has an annual global market of US $450 million. In Mexico, carrageenan imports doubled during the last years, reaching 4,400 t in 2008. Any carrageenan industrial project demands a regular supply of raw material from reliable sources capable to meet and maintain required volumes and qualities. Some carrageenophytes have been exploited traditionally in Baja California Peninsula (i.e., Chondracanthus canaliculatus). The recent demand, however, for carrageenan has increased the development of cultivation of economically important seaweeds mainly in the tropics. In the Yucatan peninsula, experimental cultivation of native and exotic species has been carried out during the last 10 years. Eucheuma isiforme, Solieria filiformis, Halymenia floresii, and the introduced Kappaphycus alvarezii represent potential raw material sources for the production of carrageenan. Demand for iota carrageenan-producing species which could be sourced from native species is not a market priority. On the contrary, the most in demand are kappa and lambda carrageenan-producing species. In this study, we analyze the prospects for the commercial cultivation of tropical economically important seaweeds in the Yucatan peninsula.     

Cultivation and utilisation of red seaweeds in the Western Indian Ocean (WIO) Region

Seaweed farming in the Western Indian Ocean (WIO) Region is carried out in a number of countries, most of them farming Eucheuma denticulatum, Kappaphycus alvarezii and Kappaphycus striatum. These species are farmed mostly in Tanzania with limited production in Madagascar, Mozambique and Kenya; current production (2012) stands at 15,966 t (dry weight) year^?1 of Eucheuma and Kappaphycus, valued at US$ 4.2 million with 95 % of this tonnage coming from Tanzania. Other countries in the region have limited or no seaweed production owing to problems of epiphytes, ice ice and markets. The problem of epiphytes coupled with ice ice that WIO countries are facing causes die-off of Kappaphycus which is the preferred species in foreign markets for its thicker gel, kappa carrageenan (vs. the weaker iota carrageenan from Eucheuma). New efforts are put to curb these problems including moving seaweed farms to deeper waters and cultivation trials of other carrageenophytes as well as agar-producing species, agarophytes. Research work has been initiated to evaluate Gracilaria and Hypnea farming and processing in Tanzania, the Republic of Mauritius and Mayotte. Gracilaria farming is at experimental stages as a biofilter of fishpond effluents and as potential species for the production of agar with growth rates of 1.5–1.9 % day^?1. Hypnea farming is only being initiated in Mauritius and Mayotte at present. Other innovations including value addition by making various seaweed products and encouraging the consumption of seaweed as food at least in Tanzania and Mauritius are increasing further the importance of the seaweed farming and processing industry in the WIO Region.     

Bioremediation potential of three carrageenophytes cultivated in tanks with seawater from fish farms

Intensive fish farming discharges large amount of nutrients, the majority of which are composed of dissolved nitrogen in ammonium form, which promotes eutrophication in coastal waters. Macroalgae have been proven to effectively reduce the nutrients of fish farm effluents and at the same time increase the economic output of the aquaculture system when economically important species are utilized. In this study, the potential of three high value carrageenophytes (Kappaphycus alvarezii, Kappaphycus sp., K. striatum) to extract ammonium in fish farm effluent collected from a milkfish (Chanos chanos) fish cage was investigated. To establish economic viability of the integrated culture system, the effects of elevated total ammonia of fish farm effluent on the growth rate, phycocolloid content, and quality of these seaweeds were determined. Tank cultivation trials showed that the three carrageenophytes substantially reduced the ammonium content of the fish farm effluent (41–66% reduction efficiency) and consequently attained maximum daily growth rates of 4.41%, 2.90%, and 2.75% for K. striatum, Kappaphycus sp., and K. alvarezii, respectively. Their carrageenan content was improved. Carrageenan quality, however, was not significantly enhanced. Elevated ammonium in fish farm effluent did not adversely affect the performance of tank cultivated Kappaphycus; thus, future integration of these seaweeds in fish farms is feasible. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

DIFFERENTIAL LOCALIZATION OF CARRAGEENAN GELLING SEQUENCES IN KAPPAPHYCUS ALVAREZII VAR. TAMBALANG (RHODOPHYTA) WITH FITC-CONJUGATED CARRAGEENAN OLIGOSACCHARIDES1

The ability of kappa (κ) and iota (ι) carrageenans to form gels is dependent upon the regular repeat of disaccharide units along the carbohydrate chain. Short, chemically- and enzymatically-purified fragments of κ and ι carrageenan were conjugated to fluorescein and used as specific hybridization probes for localization of κ and ι carrageenan gelling sequences within the cells walls and intercellular matrices of Kappaphycus alvarezii (Doty) Doty. The probes label cell walls and intercellular matrices under ionic conditions appropriate for gelation of κ and ι carrageenans. The distribution of κ and ι carrageenans in the matrix and cell walls of K. alvarezii was determined with respect to cell type (epidermis, cortex, medulla, and central axis) and age. The κ-probe labels the cell walls of all cell types except epidermal in both young and old tissues. In contrast, the ι-probe labels the cell walls of the epidermis in both young and old tissue and the cell walls of the thylles only in old tissue. Both probes label intercellular matrix material; however, ι-probe labelling is very much weaker than κ-probe labelling. The results indicate that FITC-conjugated carrageenan oligosaccharides are useful tools that provide information on gelling subunit distribution.     

Low molecular weight derivatives of different carrageenan types and their antiviral activity

A number of low molecular weight (LMW) fractions of carrageenans with different structural types were obtained by free radical depolymerization (H₂O₂), mild acid hydrolysis (HCl), and a specific enzyme. Three samples of carrageenans were depolymerized: kappa-carrageenan from Chondrus armatus, kappa-carrageenan from Kappaphycus alvarezii, and kappa/beta-carrageenan from Tichocarpus crinitus with initial molecular weights of 250, 390, and 400 kDa, respectively. The chemical depolymerization by two methods resulted to LMW derivatives of carrageenans with molecular weight from 1.2 to 3.5 kDa. Oligosaccharides of kappa- and kappa/beta-carrageenans with molecular weight of 2.2 and 4.3 kDa, respectively, were obtained after enzymatic depolymerization by recombinant kappa-carrageenase from Pseudoalteromonas carrageenovora. It was shown that the antiviral activity of high molecular weight carrageenans against tobacco mosaic virus was higher than that of their LWM derivatives independently on the depolymerization method. The method of depolymerization had some influence on the antiviral activity of carrageenan. LMW derivatives of kappa- and kappa/beta-carrageenans obtained by mild acid hydrolysis showed higher antiviral activity than the products of free radical depolymerization. The oligosaccharides prepared by enzymatic degradation possessed the lowest activity.     

Investigation of the application of Acadian Marine Plant Extract Powder (AMPEP) to enhance the growth, phenolic content, free radical scavenging, and iron chelating activities of Kappaphycus Doty (Solieriaceae, Gigartinales, Rhodophyta)

An optimization study on concentration (viz. 0.01, 0.1, and 1.0 g L^?1) and dipping time (i.e., 30 and 60 min) was conducted on three different color morphotypes (i.e., reddish brown, yellowish brown and purple) of the commercial carrageenophyte Kappaphycus alvarezii (Doty) Doty. The study tested the efficacy of Acadian Marine Plant Extract Powder (AMPEP) on the growth rate and occurrence of macro-epiphytes from August to November, representing the wet season of the Philippines. The optimum concentration and dipping time were obtained at 0.1 g L^?1 and 30 min, respectively. These optimum parameters were then further verified in a commercial nursery using the yellowish brown morphotype. In another experiment, K. alvarezii (tambalang purple morphotype) and Kappaphycus striatum (Schmitz) Doty (sacol green morphotype) with, and without, AMPEP dippings were tested for their total phenolic content, free radical scavenging and iron chelating activities. Seaweed dipped in AMPEP demonstrated higher growth rates than the control. Lower concentrations (i.e., 0.01-0.1 g L^?1) and shorter dipping time (e.g., 30 min) produced higher growth rates than the highest concentration (1.0 g L^?1) and longer (60 min) dipping time. The presence of macro-epiphytes such as filamentous Ulva did not adversely affect the robust growth of the three color morphotypes of K. alvarezii. The lowest and highest growth rates obtained in a commercial seaweed nursery using the optimum concentration and dipping time of AMPEP were observed in July and January with 0.8% and 6.7% day^?1, respectively. The antioxidant content of K. alvarezii (tambalang purple) and K. striatum (sacol green) responded differently to AMPEP dipping. The changes in total antioxidant activity followed almost the same trend as in phenolic content, in both K. alvarezii (tambalang purple) and K. striatum (sacol green), whereas, the iron chelating ability of both seaweeds with and without AMPEP dipping varied monthly. The results obtained for the use of AMPEP dips for commercial Kappaphycus cultivation demonstrated an effective management tool for improved farming protocols.     

Population studies and carrageenan properties of Chondracanthus teedei var. lusitanicus (Gigartinaceae, Rhodophyta)

Features of an intertidal population of Chondracanthus teedei var. lusitanicus, which occurs in sandy basins on rocky shores of part of the Portuguese coast (Buarcos, Figueira da Foz), were studied over one year. Biomass and plant size showed a small increase in early spring (April), a marked increase in early summer (June/July) and were at a minimum in late summer. There was generally more tetrasporophytes (4–32.5%) than female gametophytes (3–29%), which contrasts with other geographical regions where C. teedei populations have been studied, such as Brazil and France. However, non-fructified thalli predominated throughout the year. Phycocolloid extracts were compared for the various stages using spectroscopic methods (FTIR, FT-Raman, ¹H- and ¹³C-NMR). These showed a hybrid carrageenan belonging to the lambda family in the tetrasporophyte and a hybrid kappa-iota-mu-nu carrageenan in the female gametophyte and non-fructified thalli. The average phycocolloid content was 34.9% dry weight, with a maximum of 43.6% in July. The combination of high available biomass and phycocolloid content makes this species a potentially important source of kappa/iota hybrid carrageenan in Portugal additional to the traditionally harvested carrageenophytes.     

Kappaphycus alvarezii (Gigartinales, Rhodophyta) cultivated in Brazil: is it only one species?

Kappaphycus alvarezii which is endemic to the Indo-Pacific region is the main raw material for kappa carrageenan production. A seedling that was cultivated in Japan (originally from the Philippines) was introduced in a trial, for aquaculture purpose, in 1995, in São Paulo State, southeastern region of Brazil. It was later introduced in Santa Catarina State, in Southern Brazil. In 1998, another seedling that was brought from Venezuela, also originally from the Philippines, was commercially introduced at Ilha Grande Bay and later on at Sepetiba Bay, both in Rio de Janeiro State. The aim of this study was to characterize 21 samples from different farms (Rio de Janeiro and Santa Catarina States) and verify if they are K. alvarezii or other species. Based on the intergenic spacer cox2-3 sequences, phylogenetic relationships were inferred through neighbor joining, maximum likelihood, and Bayesian analyses. The topology of the trees suggests that all samples from the different farms form a monophyletic group of K. alvarezii. Statistical analysis of the cox2-3 marker calculated with median-joining network showed 38 variable positions defining 15 haplotypes for the studied samples of Kappaphycus. The most frequent K. alvarezii haplotype grouped the samples cultivated worldwide with the Brazilian samples. These results are important for better productivity and are environmentally desirable for introduction purposes since the species introduced is known and will help focusing the research on this species. This knowledge can be of assistance to the government in setting up environmental and cultivation protocols to achieve sustainability in macroalgae aquaculture.     

MONOCLONAL ANTIBODIES AS MOLECULAR MARKERS FOR THE INTRACELLULAR AND CELL WALL DISTRIBUTION OF CARRAGEENAN EPITOPES IN KAPPAPHYCUS (RHODOPHYTA) DURING TISSUE DEVELOPMENT1

Carrageenan, the major cell wall carbohydrate of certain red algae, is variable in structure and gelling properties. Sequence types include gelling (kappa and iota) and nongelling (lambda) types in addition to precursors, often in hybrid molecules containing more than one precursor and/or sequence type. Molecular markers to subunits were needed to study carrageenan synthesis, cell wall organization, and the relationship between structure and function. Monoclonal antibodies were produced to carrageenan, and their specificities were determined by competitive enzyme immunoassay. Antibodies were identified with specificities related to kappa, iota, and lambda carrageenan. The patterns of immunofluorescence localization on Kappaphycus alvarezii = Eucheuma alvarezii var. tambalang (Doty) sections were distinctive for each antibody. The antibody to a kappa-related epitope labeled mature tissue strongly; antibodies to an iota-related epitope and a lambda-related epitope labeled weakly, consistent with the kappa-enriched carrageenan produced by this alga. Kappa-related epitopes were distributed throughout the wall and matrix, whereas iota-related epitopes were concentrated in the middle lamella. Lambda-related epitopes were localized primarily at the plant cuticle where kappa and iota antigens were lacking. An antibody appeared to be specific for a precursor of the gelling subunits because it showed maximal wall and intracellular labeling at the youngest developmental stage. All antibodies labeled intracellular inclusions in the transition zone between the epidermis and medulla during the development of medullary cells from the peripheral meristem in young branches. The results demonstrate the intracellular synthesis of epitopes related to all major carrageenan subunits and their differential extracellular distribution.     

Chemical screening of Brazilian marine algae producing carrageenans

The yield, IR spectra, 3,6-anhydro-d-galactose and sulfate content are given for several species of putative carrageenophytes from different sites on the Brazilian coast. Kappa carrageenan was found in Hypnea musciformis and Gigartina spp. ; all the other species tested yield an iota type. The lowest carrageenan yield was found in Cryptonemia crenulata (5%), and the highest in Gigartina sp. (72%); 3,6-anhydrogalactose content was highest in Hypnea musciformis and Gigartina spp., whereas sulfate was lowest in H. musciformis. Slight variations in the yield of carrageenans were found during the period of observation (March 1988 to May 1989), but no clear pattern could be recognized. No significant variation was observed in plants from different collection sites.     

Seasonal variations in thalli and carrageenan composition of Gigartina pistillata (Gmelin) Stackhouse (Rhodophyta, Gigartinales) harvested along the Atlantic coast of Morocco

The biology and biochemistry of Gigartina pistillata (Gmelin) Stackhouse collected monthly at Nation Beach (Morocco), was studied during one year. The biological study showed one period of active growth from April to July. The thallus composition was quite stable during the major part of the year. The dry matter was maximum in May and August and minimum in January. The maximum carrageenan content occurred in June and September (about 37%) and the minimum carrageenan content occurred in February (19.0%). The total nitrogen content varied significantly, with a maximum in January (1.98%) and a minimum in August (0.7%). The ash content was significant (23–32%) with a maximum in August and a minimum in May. The carrageenan extracted from natural populations of Gigartina pistillata was a mixture of lambda‐type and kappa‐type carrageenans. The 3,6‐anhydrogalactose varied between 4.5 mol% in June to 25 mol% in February. For industrial applications the extract could be considered as a lambda‐type. The best period for harvest of G. pistillata in Morocco is between July and August when biomass and viscosity are at their maximum. A relationship between the physical characteristics of G. pistillata carrageenans and its seasonal cycle was deduced.     

Chemical and gelling profile of ice-ice infected carrageenan from Kappaphycus striatum (Schmitz) Doty “sacol” strain (Solieriaceae, Gigartinales, Rhodophyta)

The occurrence of ice-ice disease in farmedKappaphycus spp. has tremendous implication on thecarrageenan industry in the Philippines. To elucidate the effect of thisdiseaseon the carrageenan quality, the chemical profile of carrageenan extracted fromhealthy and diseased Kappaphycus striatumsacol strain, was investigated using ¹³C and¹H NMR, FT-IR and GPC methods of analysis. The native carrageenanextracts were composed predominantly of kappa carrageenan with trace amounts ofiota and 6-O-methylated carrageenan. Structural evidence indicatesdepolymerization of carrageenan from the ice-ice infectedportion of the thallus (whitish and soft part) lowered levels of iota andmethylconstituents. This finding was correlated to its low number average molecularweight (30 kDa) value. Accordingly, appreciable decreases incarrageenan yield, gel strength and viscosity and increase in syneresis indexwere noted. On the other hand, archetype quality of kappa-carrageenan wasobserved from both healthy and uninfected portion of the diseased thalli.     

Evaluation of growth rate and semi‐refined carrageenan properties of tissue‐cultured Kappaphycus alvarezii (Rhodophyta,Gigartinales)

This study aimed to evaluate and compare the quality of κ‐carrageenan obtained from tissue‐cultured and field‐cultured Kappaphycus alvarezii. Carrageenan properties including yield, viscosity, gel strength and sulfate content were studied. After 60 days of cultivation, tissue‐cultured K. alvarezii showed a higher growth rate (6.3 ± 0.01% day^?1) than field‐cultured seedlings (3.4 ± 0.3% day^?1). The obtained carrageenan yield from tissue‐cultured (67.3 ± 16.4%) was higher than field‐cultured K. alvarezii (51.5 ± 21.0%). Gel viscosity of carrageenans from tissue‐cultured K. alvarezii (1280.0 ± 25.0 cP) was found significantly higher than field‐cultured samples (87.8 ± 20.9 cP). The 1.5% gel solution of tissue‐cultured and field‐cultured K. alvarezii exhibited gel strengths of 703.5 ± 14.1 and 288.3 ± 19.3 g cm^?2, respectively. The average sulfate content of carrageenans was found to be significantly different between tissue‐cultured and field‐cultured K. alvarezii with 34.2 ± 10.9 and 7.5 ± 6.7%, respectively. Tissue culture is recommended to produce high quality seedlings by providing optimized culture conditions to the seaweed. This approach can serve as an alternative way to solve the seedling shortage problems currently faced by the seaweed industry.     

Introduction of non-native species of Kappaphycus (Rhodophyta, Gigartinales) in subtropical waters: Comparative analysis of growth rates of Kappaphycus alvarezii and Kappaphycus striatum in vitro and in the sea in south-eastern Brazil

We compared the growth rates of Kappaphycus alvarezii (Doty) Doty ex P. Silva and Kappaphycus striatum (Schmitz) Doty, both, in vitro under different conditions of light and temperature, and in the sea. Temperature was the most important factor controlling the growth of both species, in vitro and in the field. In the sea there was a clear seasonal pattern in growth rate, attributed to temperature and salinity variation. The lower growth rates were registered in winter and spring, and the highest in summer and autumn months for both species. Based on growth rate in the field, and the production of viable tetraspores during the summer in Kappaphycus striatum, we conclude that is more profitable, and ecologically safer, to only continue with the introduction program of Kappaphycus alvarezii.     

Kappaphycus malesianus sp. nov.: a new species of Kappaphycus (Gigartinales,Rhodophyta) from Southeast Asia

A new species, Kappaphycus malesianus, is established as a new member of the genus Kappaphycus. Locally known as the “Aring-aring” variety by farmers in Malaysia and the Philippines, this variety has been commercially cultivated, often together with Kappaphycus alvarezii due to the similarities in morphology. Despite also producing kappa-carrageenan, the lower biomass of the K. malesianus when mixed with K. alvarezii ultimately affects the carrageenan yield. Morphological observations, on both wild and cultivated plants, coupled with molecular data have shown K. malesianus to be genetically distinct from its Kappaphycus congeners. The present study describes the morphology and anatomy of this new species as supported by DNA data, with additional morphological features for distinguishing between commercial Kappaphycus cultivars.     

Anticoagulant activity, paw edema and pleurisy induced carrageenan: Action of major types of commercial carrageenans

Considering the use of commercials carrageenans as a model for inflammation, the aim this work is a comparative study these compounds in the pro-inflammatory action by ear edema and pleurisy and to analyze their anticoagulant activity. Paw edema was induced by injecting kappa, iota and lambda carrageenans in saline solution into the hind paw of male Wistar rats (p < 0.05). The three types of carrageenans showed different volume in pleural exudates, characterized by fluid accumulation, a large number of neutrophils and raised NO production (p < 0.001). The activated partial thromboplastin time (aPTT) for kappa and iota carrageenans (100 μg) was 240 s and 132 s, respectively. Lambda carrageenan was the most potent anticoagulant at 240 s (20 μg). These carragenans demonstrated no anticoagulant action using the PT test in vitro. Histological analysis in paw edema demonstrated that iota and lambda carrageenans showed major cellular infiltration in relation to kappa. Thus, quantitative evaluation of inflammation demonstrated that iota and lambda carrageenans have higher inflammatory potential than do kappa carrageenans.     

Relationships among Eucheuma denticulatum,Eucheuma isiforme and Kappaphycus alvarezii (Gigartinales,Rhodophyta) based on nuclear ssu-rRNA gene sequences

The nuclear genes encoding small-subunit ribosomal RNAs (ssu-rDNAs) of the carrageenophytes Eucheuma denticulatum, E. isiforme and Kappaphycus alvarezii were amplified by the polymerase chain reaction, cloned and sequenced. The sequences range from 1767 (K. alvarezii) to 1781 (E. isiforme) nucleotides in length, and have guanine+cytosine contents between 51.2% (E. isiforme) and 51.5% (E. denticulatum). Pairwise sequence identities among these sequences ranged from 97.6% to 98.5%, levels comparable to some intergeneric identities within Gracilariales. In phylogenetic analyses, the two Eucheuma ssu-rDNAs group stably together vis-a-vis the ssu-rDNA of K. alvarezii, and these three ssu-rDNAs form a monophyletic group within a larger grouping of other carrageenophytes. The results demonstrate quantitatively that analysis of nuclear-encoded ssu-rDNA sequences is likely to be useful in resolving taxonomic, phylogenetic and biogeographic questions among tribe Eucheumatoideae Doty.     

Karyology,nuclear genome quantification and characterization of the carrageenophytesEucheuma andKappaphycus (Gigartinales)

DNA reassociation kinetics were used to determine nuclear genome organization and complexity in the carrageenophyteKappaphycus alvarezii. Results indicate the presence of three second order components corresponding to fast (12%), intermediate (38%) and slow (50%) fractions. Microspectrophotometry with the DNA-localizing fluorochrome DAPI confirmed ploidy level differences in the gametophytic and tetrasporophytic phases. Comparison of mean nuclear DNA (I _f ) values to chicken erythrocytes (RBC) resulted in pg/2C genome estimates:Eucheuma denticulatum=0.35,E. isiforme=0.44,Kappaphycus alvarezii=0.32 andK. striatum=0.42. Karyological studies of tetraspore mother cells during diakinesis using aceto-orcein revealed a chromosome complement of 10 forEucheuma denticulatum andKappaphycus alvarezii.     

Does biofouling influence <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Doty) Doty ex Silva farming production in Brazil?

The commercial cultivation of Kappaphycus alvarezii is the main source of raw material for the carrageenan industry. Brazilian commercial farming uses floating rafts that serve as substrata for fouling organisms that may affect production of the carrageenophyte seedlings. The aim of this work was to identify and quantify the biofouling on floating rafts at Sepetiba Bay, Rio de Janeiro State (23° 02′ 25″ S and 43° 53′ 39″ W), and to evaluate seedling damage caused by epibionts and endobionts. Samples were collected from August 2006 to August 2007. In each assessment, organisms contained in random sampling areas of 18 quadrats of 0.10 m² (n = 18) were removed from floating rafts. K. alvarezii seedling samples were collected to verify the presence of epibionts or endobionts (n = 30). Twenty-four taxa belonging to seven groups of animals and three groups of seaweed were found. The percentage occurrence estimated 13 dominant organisms and amphipod tubes: e.g., Chondracanthus tedii, Cladophora vagabunda, Gracilariopsis tenuifrons, Hypnea spinella, Hypnea musciformis, Hincksia mitchelliae, Spyridia spp., Ulva spp., Bowerbankia sp., Bugula neritina, Botryllus sp., Haplosclerida sp., and Perna perna. Richness, equitability, diversity, and total biomass varied significantly during the study period (p < 0.001). There was a tendency for higher biomass values in August 2007. After 6 months, epibionts (i.e., Chlorophyta, Rhodophyta, Chordata, Cnidaria and Ectoprocta) were found on K. alvarezii seedlings. Endobionts were not found in this study. The biofouling biomass was not found to have a significant effect on K. alvarezii daily growth rate, carrageenan yield, or quality (gel strength and viscosity; p > 0.05).     

Genetic diversity of Kappaphycus Doty and Eucheuma J. Agardh (Solieriaceae,Rhodophyta) in Southeast Asia

The commercial importance of carrageenophytes Kappaphycus and Eucheuma is well known, with much interest in terms of cultivation, marketing, and research. Considering the many lucrative prospects, these red seaweeds were introduced into various parts of the world for farming, where merely a few were comprehensively documented. Despite being extensively cultivated throughout Southeast Asia, the genetic diversity of Kappaphycus and Eucheuma is poorly studied, where heavy reliance is placed on the use of local or commercial names for identifications. This study used the mitochondrial-encoded cox1 and cox2–3 spacer genetic markers to investigate the Kappaphycus and Eucheuma haplotypes, cultivated and wild, available throughout Southeast Asia. Concatenated cox1–cox2–3 spacer datasets were also analyzed. The near full-length cox1 gene is preferred at revealing the genetic diversity of Kappaphycus and Eucheuma, provided a larger reference database is available. Both molecular markers were capable of delineating common members of the genus Kappaphycus (i.e., Kappaphycus alvarezii, Kappaphycus striatus, and Kappaphycus cottonii) and Eucheuma denticulatum, and revealed interesting genotypes and new species which may be potential alternatives to the common cultivars as well as materials for research. The relative scarcity of Eucheuma species is discussed and future sites for sampling are recommended.