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.     

Phylogenetic relationship of Kappaphycus Doty and Eucheuma J. Agardh (Solieriaceae, Rhodophyta) in Malaysia

The genera Kappaphycus Doty and Eucheuma J. Agardh are important sources of carrageenan in Malaysia, offering lucrative revenues to the carrageenan industry, economy, and the local community. The extensive range of morphotypes and the lack of distinct morphological characteristics led to the application of molecular systematics in elucidating this taxonomic confusion. Local varieties of Kappaphycus and Eucheuma, identified using putative external morphology, were analyzed using the mitochondrial cox2–3 spacer and plastid RuBisCO spacer molecular markers. Phylogenetic analysis of these and non-local specimens indicate that Kappaphycus and Eucheuma are genetically distinct. Three main genotypes of Kappaphycus alvarezii were identified, of which two are extant in Hawaii. Morphological and color variations are not supported by molecular data, indicating that most of the local names are not genetically based. Both the cox2–3 spacer and RuBisCO spacer generated phylogenetic trees with similar topology except in variation of nodal supports. The two markers showed clear separation between Kappaphycus and Eucheuma and the existence of three Malaysian Kappaphycus cultivars. Cox2–3 spacer data is more variable and provides better resolution than the RuBisCO spacer, showing that Kappaphycus is more diversified with a larger number of genotypes, strains, and species which are unique to Southeast Asia. Kappaphycus sp. “Aring-aring” appeared to be phenotypically and genotypically different from other Kappaphycus congeners, whereas Kappaphycus striatum exhibited two different genotypes. Our data indicate that Eucheuma denticulatum is the dominant species in Malaysian waters and also suggested paraphyly in Eucheuma which will require further studies. The application of molecular taxonomy on Malaysian Kappaphycus and Eucheuma proves useful, offering valuable insights into the taxonomy and distribution of these commercially important Rhodophytes.     

Systematics and genetic variation in commercial shape Kappaphycus and shape Eucheuma (Solieriaceae, Rhodophyta)

The systematics and taxonomy of Kappaphycus and Eucheuma (Solieriaceae) is confused and difficult due to morphological plasticity, lack of adequate characters to identify species and commercial names of convenience. These taxa are geographically widely dispersed through cultivation. Commercial, wild and herbarium sources were analysed; molecular markers provided insights into taxonomy and genetic variation, and where sources of genetic variation may be located. The mitochondrial cox2-3 and plastidal RuBisCo spacers were sequenced. There is a clear genetic distinction between K. alvarezii (“cottonii”) and K. striatum (“sacol”) samples. Kappaphycus alvarezii from Hawaii and some samples from Africa are also genetically distinct. Our data also show that all currently cultivated K. alvarezii from all over the world have a similar mitochondrial haplotype. Within Eucheuma denticulatum (“spinosum”) most African samples are again genetically distinct. Our data also suggest that currently cultivated E. denticulatum may have been “domesticated” several times, whereas this is not evident for the cultivated K. alvarezii. The present markers used do not distinguish all the morpho-types known in cultivation (e.g. var. tambalang, “giant” type) but do suggest that these markers may be useful to assess introductions and species identification in samples.     

Genetic diversity of Kappaphycus species (Gigartinales,Rhodophyta) in the Philippines

The mariculture of eucheumatoids (species of Kappaphycus and Eucheuma) in the Philippines has had a long history, dating back to the 1970s. Over this period, a number of varieties have been brought into domestication; some are now widely distributed and farmed in various regions of the country, but a significant number appear to have a more restricted distribution and are farmed only in certain areas. The taxonomy of many of these seaweed cultivars and their phylogenetic relationships still remain to be resolved at the specific and subspecific levels. In this study, two mitochondrial DNA markers, COI-5P region and cox2-3 intergenic spacer, were used to assess the genetic diversity of the farmed varieties and a few specimens collected from the wild. Analysis using haplotype networks revealed several new haplotypes for K. alvarezii, K. malesianus and K. striatus, mainly from specimens collected from eastern and southwestern regions of the Philippines. The inferred phylogenetic relationships based on both mtDNA markers resolved the identity of all the materials used in the study at the species level. We present molecular evidence that K. malesianus, in addition to K. alvarezii, K. cottonii, K. inermis, K. procrusteanus and K. striatus (and, hence, all currently recognized species of Kappaphycus) occurs in the Philippines. Collectively, these observations suggest that the Philippine archipelago has richer genetic diversity of farmed and wild Kappaphycus than do the other geographic regions, consistent with the hypothesis that the Philippines is, or is part of, the centre of Kappaphycus biodiversity in the world. These findings also reveal an untapped diversity that can potentially be exploited for improving the commercial production of these carrageenophytes.     

Effect of the commercial extract of the brown alga Ascophyllum nodosum Mont. on Kappaphycus alvarezii (Doty) Doty ex P.C. Silva in situ submitted to lethal temperatures

Kappaphycus alvarezii is being introduced in several countries and in some of them there is a need to adapt this cultivation to periods with lethal temperatures, such as the 16–18 °C that occurs in the winter in southern Brazil. Moreover, there is the need to maintain the seedlings during this lethal temperature period. Considering the promising results obtained with the commercial powder extract of Ascophyllum nodosum (Acadian marine plant extract powder—AMPEP) treatment in the cultivation of K. alvarezii in vitro and in the sea allowing more resistance to epiphytes and increasing the growth rate and carrageenan yield, it was hypothesized that seedlings previously subjected to an AMPEP treatment could be more resilient to lethal temperatures. The daily growth rate and carrageenan yield and gel quality (gel strength and gel viscosity) of K. alvarezii in vitro previously treated with AMPEP were analyzed under temperature stress. The daily growth rates and the gel strengths of the AMPEP-treated samples were increased. In spite of the lower carrageenan yield and lower gel viscosity, the values were within the ones accepted by the carrageenan industry. Thus, the treatment of the seedlings of the K. alvarezii with AMPEP solution can be used as an alternative to lower temperature effects on crops as a preventive action for the cultivation of the seedlings in tanks and in the sea in periods of low temperatures at sea.     

Macroalgae Biorefinery from <Emphasis Type="Italic">Kappaphycus alvarezii:</Emphasis> Conversion Modeling and Performance Prediction for India and Philippines as Examples

Marine macroalgae are potential sustainable feedstock for biorefinery. However, this use of macroalgae is limited today mostly because macroalgae farming takes place in rural areas in medium- and low-income countries, where technologies to convert this biomass to chemicals and biofuels are not available. The goal of this work is to develop models to enable optimization of material and exergy flows in macroalgal biorefineries. We developed models for the currently widely cultivated red macroalgae Kappaphycus alvarezii being biorefined for the production of bioethanol, carrageenan, fertilizer, and biogas. Using flux balance analysis, we developed a computational model that allows the prediction of various fermentation scenarios and the identification of the most efficient conversion of K. alvarezii to bioethanol. Furthermore, we propose the potential implementation of these models in rural farms that currently cultivate Kappaphycus in Philippines and in India.     

Clonal production of <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Doty) Doty in vitro

Micropropagation has proven to be a reliable method to mass produce certain crops. This method also has been applied in macroalgae to produce clones for seaweed farming. Protocols for callus production and shoot regeneration from protoplasts have been established for some seaweed species like Kappaphycus alvarezii. Cells and larger tissues, whether in solid or suspension medium, have been used to propagate clones which were later tested for suitability for farming. Although clonal production was successful, the long duration of culture in vitro limits the production process making the growing of Kappaphycus in vitro an expensive technique to produce clones. In this study, K. alvarezii was grown in vitro to develop a more efficient protocol for the production of clones. Small sections of Kappaphycus were grown in suspension for 1 month under the same temperature, light, and salinity. The type of media, source of explants, length of explants, and stocking density that resulted in the highest growth rate and survival rate were determined. Growth rate of K. alvarezii is significantly higher in media with inorganic nitrogen added than in Grund medium or Ascophyllum nodosum medium only. The appearance of shoot primordia as early as 5 days was observed in media with higher nitrogen concentration. Growth rates of explants approximately 3 and 5 mm are significantly higher than 10 mm sections. Shoots develop significantly faster in explants from tips than sections from older branches. Growth rate of K. alvarezii grown at 0.5, 0.75, 1, 1.25 s 10 mL^?1 of medium is not significantly different. This protocol could significantly reduce the (1) time of culture and (2) cost of plantlets production by not using plant growth regulators and formulated media in vitro. Nursery reared plantlets/propagules for farming would be affordable to the stakeholders for sustainability of seaweed production.     

Optimization of culture conditions for the direct regeneration of Kappaphycus alvarezii (Rhodophyta,Solieriaceae)

Cultivation of seaweeds on a commercial scale requires a large number of propagules with desirable phenotypic traits which include high growth rates and resistance to diseases. Seaweed micropropagation can be considered as one of the best methods to provide a large amount of seedlings for commercial cultivation. This study was carried out to optimize the parameters known to affect the growth of Kappaphycus alvarezii in vitro and subsequently improve the production of seedlings through micropropagation. Suitability of media, concentration of phytoregulators, types and concentration of fertilizers, culture density, light intensity, interval of aeration activity, salinity, and pH were found to be critical factors for the growth of K. alvarezii. The optimum condition for direct regeneration of K. alvarezii in a culture vessel was found to be cultivation of explants in Provasoli's enriched seawater (PES) media supplemented with 2.5 mg L^?1 6-benzylaminopurine (BAP), 1.0 mg L^?1 indole-3-acetic acid (IAA), and 3.0 mg L^?1 natural seaweed extract (NSE) with culture density of 0.4 %?w/v, under light intensity of 75 μmol photons m^?2 s^?1, continuous aeration of 30.0 L h^?1, salinity of 30.0 ppt, and pH 7.5. An airlift photobioreactor was constructed for the mass propagation of K. alvarezii explants with optimum culture conditions obtained from the study. The optimum growth rates of the K. alvarezii explants in culture vessels (5.5 % day^?1) and photobioreactor (6.5 % day^?1) were found to be higher than the growth rate observed in field trials in the open sea (3.5 % day^?1). The information compiled during the course of this study will be of utility to commercial seaweed cultivators.     

Ultrastructural,morphological, and molecular characterization of Colaconema infestans (Colaconematales,Rhodophyta) and its host Kappaphycus alvarezii (Gigartinales,Rhodophyta) cultivated in the Brazilian tropical region

Endophytic and epiphytic infections have caused serious problems for Kappaphycus farmers, such as reduction in biomass production and decrease in the yield and quality of carrageenan. During environmental monitoring from January 2011 to December 2012, along Pitimbu Beach, Paraíba State, northeastern Brazil, drifting thalli of Kappaphycus alvarezii (Gigartinales, Rhodophyta) were detected with red spots, apparently caused by epiphytic/endophytic infections. Therefore, drifting thalli of K. alvarezii farmed along the northeastern Brazilian coast were cultured in the laboratory and submitted to molecular and morphological analyses to identify and characterize the causative agent and its effects on the cellular structure and ultrastructure of the host alga K. alvarezii that was found to be infected by the endophyte Colaconema infestans (Colaconematales) identified through morphological and rbcL molecular evidence. Infected thalli of K. alvarezii were processed and analyzed through light, transmission electron, and scanning electron microscopy. Alterations were observed in morphology and cellular organization, including structural changes of chloroplasts and decrease in floridean starch grains, along with increased cell wall thickness. Therefore, while no outbreak has been reported, the discovery of C. infestans infection in drifting thallus of K. alvarezii suggests a potential threat to its cultivation that should be monitored.     

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.     

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.     

Inhibitory activities of three Malaysian edible seaweeds on lipase and α-amylase

Ethanol extracts, dried powders and fibres (total and soluble fibre) of the tropical red algae Kappaphycus alvarezii, Kappaphycus striatus and Eucheuma denticulatum were analysed for their effect on lipase and α-amylase activity using turbidimetric method and dinitrosalicylic acid (DNS) assay, respectively. The nutrient composition analyses were determined using standard methods. The ethanol extract of dried K. striatus (Ks-III) showed the highest reduction in lipase activity with 92 % inhibition followed by seaweed powders (K. alvarezii (Ka-III), K. striatus (Ks-III) and E. denticulatum (Ed-III)) with average inhibition of 60 %. Soluble fibres of K. alvarezii (Ka-V) and E. denticulatum (Ed-V) showed significant inhibition with 60 and 57 % reduction, respectively. Only the ethanol extract of fresh E. denticulatum (Ed-I) showed 88 % inhibition of α-amylase. Nutritional component analyses showed that all three seaweeds are low in crude fat, suggesting the possible use of seaweed as a dietary supplement and for potential weight and glycaemia management.     

Occasional pathogenic bacteria promoting ice-ice disease in the carrageenan-producing red algae Kappaphycus alvarezii and Eucheuma denticulatum (Solieriaceae,Gigartinales, Rhodophyta)

The bacterial isolates from normal and diseased branches of Kappaphycus alvarezii and Eucheuma denticulatum in the Philippines were examined for possible role in the development of the ice-ice disease. The numbers of bacteria on and in ice-iced branches were 10–100 times greater than those from normal, healthy ones. Gram-positive bacteria predominated in almost all branch sources, but with an increasing proportion of agar-lysing bacteria in branches suffering from the ice-ice disease. These agar-lysing bacteria were composed of yellow and non-pigmented, spreading colonies identified to the Cytophaga-Flavobacterium complex and the Vibrio group. Among isolates which mainly appeared on ice-iced branches, two strains, designated as P11 (Vibrio sp.) and P25 (Cytophage sp.), which showed pathogenic activity, were obtained. These strains caused early ice-ice whitening of K. alvarezii especially when subjecting branches to environmental stress, such as reduced salinity and light intensity, suggesting that these bacteria were occasionally pathogenic. This paper offers new evidence of bacterial role in the development of so-called ice-ice disease among farmed species of Kappaphycus.     

Ploidy determination of three Kappaphycus alvarezii strains (Rhodophyta, Gigartinales) by confocal fluorescence microscopy

Kappaphycus alvarezii is a red alga that is commercially important as a source of carrageenan. Since K. alvarezii presents large phenotypic plasticity and rarely develops reproductive structures in culture, identification of gametophytic and tetrasporophytic phases in cultivation systems are difficult. The aim of this study was to determine the ploidy of three K. alvarezii strains previously identified as brown “tetrasporophyte”, brown “gametophyte” and “Edison de Paula” (EP). Nuclei from these strains were stained with DAPI, and analyzed using confocal fluorescence microscopy and ImageJ software. The brown “tetrasporophyte” had the highest nuclear fluorescence intensity, consistent with a diploid tetrasporophyte (2N). The brown “gametophyte” and “EP” strains had nuclear fluorescence intensities of 55.78% and 57.10% in relation to the tetrasporophyte, respectively, consistent with haploid gametophytes (N). The present study demonstrated that this technique can be used as a rapid and effective tool to distinguish between haploid (gametophytic) and diploid (tetrasporophytic) plants of K. alvarezii, in addition to help identify new strains developed through alterations of ploidy level.     

The commercial red seaweed <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis>—an overview on farming and environment

Commercial cultivation of the red alga Kappaphycus alvarezii (Doty) Doty has been satisfying the demand of the carrageenan industry for more than 40 years. For the past four decades, this species has been globally introduced to many maritime countries for experimental and commercial cultivation as a sustainable alternate livelihood for coastal villagers. Accompanying the introduction is an increasing concern over the species effects on the biodiversity of endemic ecosystems. The introductions of non-endemic cultivars have resulted in the adaptation of quarantine procedures to minimize bioinvasions of additional invasive species. The present review focuses on Kappaphycus farming techniques through the application of biotechnological tools, ecological interactions with endemic ecosystems, future K. alvarezii farming potentials in Asia, Africa, and the Pacific, and the challenges for prospective farmers, i.e., low raw material market value, diseases, grazing, etc. The introduction of Kappaphycus cultivation to tropical countries will continue due to the high production values realized, coastal villages searching for alternative livelihoods, and the increased global industrial demand for carrageenan.     

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.     

Impacts of glyphosate on photosynthetic behaviors in Kappaphycus alvarezii and Neosiphonia savatieri detected by JIP-test

Neosiphonia savatieri, a filamentous red alga, had spread and caused a massive death of its host Kappaphycus alvarezii since March 2009 in China. With an aim to found a specific method to eliminate the N. savatieri efficiently from carrageenan producing K. alvarezii, the effects of glyphosate on the photosynthetic behaviors of K. alvarezii and N. savatieri were comparatively studied by using fast chlorophyll a (Chl a) fluorescence kinetics. A dose- and time-dependent changes of fast Chl a fluorescence kinetics were obtained in N. savatieri treated by glyphosate, meanwhile no significant change was detected in the K. alvarezii under the same treatment conditions. Moreover, the maximum PSII photochemical efficiency for dark-adapted tissues (F _V/F _m) of N. savatieri decreased significantly when the N. savatieri was treated with glyphosate. Above results were further supported by transitory offshore glyphosate soak experiment. The brownish-red N. savatieri turned to be olivine then drew off within 5?days after soaking in >1?g?L^?1 of glyphosate for more than 1?min, meanwhile, no visible harmful effects were detected on K. alvarezii. Based on above results, glyphosate is suggested to be an effective chemical to eliminate N. savatieri from K. alvarezii.     

Ecological risk assessment of the introduction of exotic carrageenophytes in the tropical Western Atlantic

The potential risks of cultivating carrageenophyte genera for commercial purposes in the circumtropical belt are debated. However, species introductions of two such genera, Kappaphycus Doty and Eucheuma J. Agardh, have been reported in 30 different locations in this region over the last 30 years. On several occasions, these introductions did not adequately evaluate potential environmental risks or were conducted without approval from local regulatory bodies. In the present paper, a working protocol is proposed for the quarantine and assessment of the possible effects of the introduction of Kappaphycus alvarezii and Kappaphycus striatus to shallow marine ecosystems of the tropical Western Atlantic. This protocol is based on field data following from the introduction of eucheumoids onto the Cuban shelf in the early 1990s. It was demonstrated that the propagation of either carrageenophyte in oligotrophic waters of the Cuban Archipelago did not pose a potential risk to the region’s biodiversity due to the synergic combination of high herbivory and low rates of growth. Physical features of the substrate and depth were the most important regulators of grazing. These environmental conditions restrict potential cultivation sites in the Cuban Archipelago to a few small regions where nutrient pulses are well established. In these areas, when the canopy of cultivated carrageenophytes is sufficiently high, a significant effect on benthic communities is observed. In consideration of the need to protect places with high intrinsic value, this fact should be considered during site selection.     

Bioethanol production from the acid hydrolysate of the carrageenophyte Kappaphycus alvarezii (cottonii)

Seaweed resources can be used as raw materials to produce bioethanol, a renewable biofuel, to overcome fossil fuel depletion and environmental problems. Red seaweeds possess high amount of bioethanol-producible carbohydrates. Among 55 species tested, the carrageenophyte Kappaphycus alvarezii (also known as cottonii) was selected as the best resource for bioethanol production. This species is one of the most abundant and easily cultured red seaweeds. The main components of carrageenan are d-galactose-4-sulfate and 3,6-anhydro-d-galactose-2-sulfate, which are potentially fermentable d-typed carbohydrates. The seaweed powder was hydrolyzed with 0.2?M sulfuric acid and fermented with brewer’s yeast. The ethanol yield from the K. alvarezii hydrolysate was 0.21?g?g^?1-galactose, which corresponded to a 41% theoretical yield. It revealed a relative ethanol production of 66% comparing to that of pure galactose.     

A molecular method for identification of the morphologically plastic invasive algal genera Eucheuma and Kappaphycus (Rhodophyta, Gigartinales) in Hawaii

A paucity of diagnostic morphological characters for identification and high morphological plasticity within the genera Eucheuma and Kappaphycus has led to confusion about the distributions and spread of three introduced eucheumoid species in Hawaii. Entities previously identified as E. denticulatum, K. alvarezii, and K. striatum have had profound negative effects on Oahu’s coral reef ecosystems. The use of molecular tools to aid identification of algal species has been promising in other morphologically challenging taxa. We used three molecular markers (partial nuclear 28S rRNA, partial plastid 23S rRNA, and mitochondrial 5′ COI) and followed a DNA barcoding-like approach to identify Eucheuma and Kappaphycus samples from Hawaii. Neighbor-joining analyses were congruent in their separation of Eucheuma and Kappaphycus, and the resulting clusters were consistent with those revealed for global comparisons with the mitochondrial cox2-3 spacer and GenBank data. Based on these results, new insights were revealed into the distribution of these groups in Hawaii.