A pilot-scale study of the vegetative propagation and suspended cultivation of the carrageenophyte alga Gigartina skottsbergii in southern Chile

Different propagation techniques for cultivation of vegetative Gigartina skottsbergii fronds were tested using a system of suspended ropes, to which inoculants were attached. Our results showed that triangular fragments obtained from the circular G. skottsbergii thalli produced harvestable frond of 800 cm² after 8 months. In contrast, inoculants of intact juvenile fronds of comparable size needed at least 10 months to reach the same size. A control experiment with spores developing on an artificial substrate showed that 20 months were needed to reach a surface of 500 cm², confirming the superiority of our fragment culture system. A pilot study demonstrated that with a density of six fronds m⁻¹ of farming line, the proposed system can be economically interesting for local fishermen.     

Cultivation of Gigartina skottsbergii (Gigartinales, Rhodophyta): Recent advances and challenges for the future

This study integrates landings statistics and biological studies of the red algaGigartina skottsbergii Setchell & Gardner. The analysis of the landings and carrageenan production in Chile suggeststhat this resource will suffer a strong harvesting pressure during the nextyears. Biological results on sporulation, germination, sporeling growth and survivorship in laboratory,indoor tanks and field conditions, indicated that cultivation of this species istechnically feasible, as spores can be seeded on ropes and other substrata. Vegetative propagation of this species through tissue fragmentationis also possible. Vegetative fragments of this carrageenophyte have 20 to30% higher growth rates than whole fronds in suspended culture systems. Protoplast production can be also explored for bypassing restrictions inspore availability. Major advantages that encourage the cultivation of G. skottsbergii include its gel quantity and quality, its pathogen-freecondition, a high reproduction potential and its regeneration capacity. Onthe other hand, the major constraints are related to its relatively slowgrowth as compared to other carrageenophytes, limited availability ofspores and high mortality during juvenile stages.     

Effects of UVB Radiation on the Initial Stages of Growth of Gigartina Skottsbergii, Sarcothalia Crispata and Mazzaella Laminarioides (Gigartinales, Rhodophyta)

The effects of UVB radiation on the growth of macroalgal thalli were evaluated using tetrasporophytic fronds of the Rhodophytes Gigartina skottsbergii, Sarcothalia crispata and Mazzaella laminarioides. The tetrasporophytic fronds were collected from nature and the tetrasporophyte sporelings grown in a temperature regulated chamber at 8 ± 2 ^∘C with a 12L:12D (Light: Dark) photoperiod, Photosynthetically Active Radiation (PAR) of 55 μmol photons m⁻² s⁻¹ and seawater enriched with 20 mL L⁻¹ of Provasoli medium. We exposed the thalli of these macroalgae to PAR (55 μmol photons m⁻² s⁻¹) and three treatments using a combination of PAR with three different levels of UVB radiation (0.10, 0.15 and 0.23 W m⁻² for G. skottsbergii and S. crispata and 0.02, 0.05 and 0.10 W m⁻² for M. laminarioides) during a period of 71 days. Growth of thalli was quantified by measuring their length using digitized photographs of samples.Important differences were detected in the growth of individuals cultured under the effects of UVB radiation, when compared to the control (i.e. plants exposed to PAR only). In the case of G. skottsbergii and S. crispata higher levels of UVB radiation resulted in slower growth of thalli. In nearly all measurements for the first two species, UVB radiation levels of 0.1 W m⁻² induced differences in thallus growth, while for M. laminarioides levels of UVB radiation of 0.1 W m⁻² were effective only after a prolonged period of exposure.Differential effects of UVB radiation on G. skottsbergii, S. crispata and M. laminarioides could interfere with the natural populations of these economically important macroalgal species in southern Chile, where they occur under the annual influence of the Antarctic Ozone Hole and the general thinning of the ozone layer.     

Open-sea cultivation by transplanting young fronds of the kelp Saccharina latissima

Saccharina latissima is an economically and ecologically important native kelp. As its limited supply from wild stock cannot meet increasing current and future demands, methods for its cultivation in the ocean need to be developed. This kelp is now beginning to be farmed off the Atlantic coast of Spain using a regular method similar to the “forced cultivation” technique used with Asian kelps (kombu). Its cultivation is also a growing enterprise in other European countries. In this study, the open-sea farming of S. latissima using the transplanting method is tested on a commercial scale. This cultivation method has not been studied with kelp species outside Asian waters. The tested method includes the following steps: indoor production of seedlings, pre-culture in greenhouse tanks, and open-sea cultivation by transplanting young fronds. Results demonstrate that open-sea cultivation using transplanted young fronds is a technically and biologically viable method. The mean yield obtained (7.8 kg fresh wt per meter rope equivalent to 45.6 t fresh wt per hectare farm) is satisfactory, considering the low densities of transplanted fronds (25–30 fronds per meter rope). Moreover, these values are comparable to those reported in previous cultivations with this species, as well as in the farming of similar kelps. The transplanting method used in conjunction with the regular cultivation method has valuable practical applications for the commercial farming of S. latissima.     

Recent trends of seaweed production in Chile

In the last fourteen years the production of seaweeds in Chile has ranged from 74 000 to 229 000 wet metric tons per year and has included about twenty species belonging to Phaeophyta and Rhodophyta. The only source of this production has been the exploitation of natural beds, except for Gracilaria, which is the only case of commercial cultivation and contributes significant quantities to total production. Initially most of the raw material was exported but currently important quantities of Gracilaria and several carrageenophytes are being processed by local industry. Changes in production of the main resources are analyzed with consideration of potential demand, level of knowledge about natural beds, and the situation of total Gracilaria farming, in order to attempt predictions for the supply. Current possibilities of applying new technologies to cultivate other economically important Chilean seaweeds are also analyzed and discussed.     

Cultivation of Grateloupia acuminata (Halymeniaceae,Rhodophyta) by regeneration from cut fragments of basal crusts and upright thalli

Regeneration of Grateloupia acuminata Okamura from fragments of basal crusts and young upright thalli was studied in culture. The carpospores and tetraspores develop into basal crusts and these in turn produce upright thalli. When the crusts and the young upright thalli were cut into fragments, the fragments of basal crusts regenerated into new crusts, whereas those of upright thalli formed adventitious filaments. For cultivation in the sea, the cut fragments of basal crusts were inoculated onto oyster shells and synthetic twines of Nori-net and cultured for about one month in the laboratory. The oyster shells and the twines with regenerated crusts were then transferred into the sea from September to December. Many upright thalli developed and grew well during the cold season of the year (December to March).Author for correspondence     

Suspended cultivation of Gracilaria in the sea

Suspended rope cultivation systems for Gracilaria or Gracilariopsis can be seeded from spores but vegetative propagation is used for those which are currently commercially successful. Such systems and methods have been recently developed for the shallow lagoon areas around Lüderitz, Namibia and deeper open water sites off the Araya Peninsula, Venezuela. Various sites, substrata, depths and seeding methods have been assessed and have resulted in average commercial growth rates of about 3.5% per day. Netlon ‘Superope’ has been demonstrated to be more suitable than laid rope as a substratum for outplanted vegetative Gracilaria gracilis in Namibia as it does not compress the thalli as they grow. An efficient method, using hooks, has been developed to ‘seed’ the Superope. There is a very low incidence of algal epiphytism: mainly Ceramium and Ulva sp. In Venezuela, pilot rope cultivation systems for Gracilariopsis tenuifrons proved successful and have good commercial prospects.     

Artificial Seed Production and Cultivation of the Edible Brown Alga, Sargassum Fulvellum (Turner) C. Agardh: Developing a new Species for Seaweed Cultivation in Korea

Sargassum fulvellum is a brown alga recently introduced to the seaweed cultivation industry in Korea. There is current interest in the commercial scale of aquaculture of this species. For the artificial seeding and cultivation of this alga, growth and maturation were investigated from September 2002 to August 2003. Indoor culture experiments for maturation induction were also conducted at temperatures of 5, 10, 15, 20 and 25 ^∘C and irradiances of 20, 50, 80 and 100 μmol photons m⁻² s⁻¹ under 16:8 h (L:D) photoperiod. Within a given culture test range, higher temperature and irradiance levels favoured the maturation of receptacles in S. fulvellum. Using temperature and irradiance control for thalli, artificial seed production of this species could be done one month earlier than thalli matured in nature. Under natural condition, receptacle formation of the plants began in February, and the eggs were released from March to April. For mature thalli of 200 g wet wt., artificial seeding was complete enough for attachment on seed strings of 100 m. Mean production obtained from the artificial seeding technique in situ was 3.0 kg wet wt m⁻¹ of culture rope during the cultivation period.     

UVB effects on early developmental stages of commercially important macroalgae in southern Chile

High levels of ultraviolet-B radiation (UVB) could represent a danger to seaweeds by affecting their physiological processes and development. The aim of this work was to study the effects of UVB radiation on early developmental stages of commercially and ecologically important marine algal species in southern Chile, considering spores survival and embryos growth. Spores of Mazzaella laminarioides, Gigartina skottsbergii, Sarcothalia crispata and embryos of G. skottsbergii and Macrocystis pyrifera were submitted to treatments of a) photosynthetically active radiation (PAR: Control), b) PAR+UVA (PA) and c) PAR+UVA+UVB (PAB). UV radiation did not affect spore survival of M. laminarioides S. crispata and G. skottsbergii (P = 0.55, P = 0.6 & P = 0.25 respectively), but did provoke differences in the growth rate of G. skottsbergii embryos (P = 0.00). Differences in survival and growth of M. pyrifera embryos were also observed (P = 0.001 & P = 0.007, respectively). Differences in growth of M. pyrifera embryos were observed only in the first five days, whereas changes in survival persisted until the end of the experiment. Additionally, UVB provoked morphological alteration in M. pyrifera embryos, as evidenced by progressive curling. These results suggest that the initial stages of the subtidal algae species G. skottsbergii and M. pyrifera cultivated in laboratory conditions were sensitive to UVA and UVB radiation, and their recruitment and development could be affected as well in natural conditions found in southern South America, where the ozone layer has thinned more than in other parts of the planet.     

A comparative analysis of wild and laboratory grown Laminaria abyssalis (Phaeophyta) using modulated fluorescence

Laminaria abyssalis fronds were either collected at the Brazilian costal area - 40 meters below sea level - or grown in the laboratory. The photochemical yield as defined by the Fv/Fm and the Fo - the dark fluorescence level when all PSII centers are open - varied with the distance from the stipe to the tip of the blade in wild grown fronds while it stayed constant in the laboratory grown plants. The chlorophyll a/c ratio levels decreased in the wild fronds from 12 (near the stipe) to 6 near the top. The chlorophyll c content increased from 0.8 to near 1.7 mg cm^–2 in the wild fronds. The laboratory fronds did not show variations in their chlorophyll contents. The wild fronds pattern changed after 2 months kept in the laboratory, producing similar results to those grown in the laboratory. The results indicate that the levels of the antenna complex in the wild fronds increase from the stipe to the top of the blade, in a fashion similar of the sun/shade leaves. Also, results show, that this alga is able to adapt itself to new light conditions, possibly increasing its level of antenna complex and photosynthetic units.Abbreviations PSII Photosystem II - Fo Chlorophyll fluorescence when all PSII are opened - Fm Chlorophyll Fluorescence when all PSII are closed - Fv Variable Fluorescence (Fm-Fo) - Fv/Fm Quantum Yield for Photochemistry     

No correlation between the growth of in vitro cultured Yucca valida clones and the growth of their mother plants in the field

Yucca valida is a close relative to Yucca schidigera and a potential alternative source of the steroidal saponins extracted from the tissues of the latter. The exploitation from the wild is not only inefficient but endangers the natural populations and an alternative to these would be their domestication and establishment of commercial plantations. Both species have a long life span cycle and low growth rates affected by environmental conditions that make it difficult to select fast growing, high yield elite individuals for cloning purposes. Here, we report the in vitro establishment and propagation of mature Y. valida plants derived from seed that showed very different growth rates in an experimental field and their propagative and growth characteristics in vitro. No correlation was found between the growth of field cultivated plants and the relative increase of fresh (FW) or dry weight (DW) of in vitro cultured plants.     

Production and application of filaments of <Emphasis Type="BoldItalic">Grateloupia turuturu</Emphasis> (Halymeniaceae,Rhodophyta)

Filaments from Grateloupia turuturu were obtained through germination of spores, regeneration from fragments of discoid crusts and erect thalli. The rates of filament formation through the three ways were 5.3 ± 1.2%, 100%, and 62.3 ± 5.6%, respectively. Discoid crusts were the best materials for the production of filaments. The obtained filaments were cloned in stationary and aerated culture. The differentiations of filaments were observed. When attached to the substrata, filaments differentiated into discoid crusts from which erect thalli grew, whereas for filaments in suspension culture, some cells in the filaments differentiated into spherical structures that also formed new erect thalli. Moreover, fragments of filaments (< 100 μ m) were seeded onto nori-nets. The regenerated plantlets grew into adult thalli in field cultivation.     

Growth and survival performance of the gametophyte of Gigartina skottsbergii (Rhodophyta, Gigartinales) under defined nutrient conditions in laboratory culture

Gigartina skottsbergii is a commercially important carrageenan producer that has been suffering severe extraction pressure in Chile’s Magellan Region and Cape Horn Archipelago since 1998. In order to create baseline information for its cultivation and repopulation, we studied the effects of agricultural fertilizers on growth of G. skottsbergii early developmental stages. The culture media utilized were: a) seawater + Bayfoland, b) seawater + Superphosphate, c) seawater + Urea, d) seawater + Provasoli and e) seawater as a control. The culture conditions were: a) 12L:12D photoperiod; b) temperature 8 ± 1°C and c) irradiance at 45 μmol photons m⁻² s⁻¹. After 60 days, higher relative growth rates between treatments were observed; the treatments that included Bayfoland and Provasoli showed greater growth (382 ± 55 and 378 ± 50 μm, respectively,) compared to Superphosphate (88 ± 16 μm), control (78 ± 10 μm) and Urea (70 ± 11 μm) treatments, after 81 days. The Urea treatment and the control had inhibitory effects on G. skottsbergii germlings growth and survival, as evidenced by progressive loss of pigmentation and death after 60 days. These results showed that Bayfoland was an excellent alternative to develop cultures.     

A review of the life history,reproduction and phenology of Gracilaria

The basic life history of the red alga Gracilaria is of the three-phase Polysiphonia type but a number of species show deviations. Plants can bear both gametangia and tetrasporangia, either on separate parts of the thallus or on the same. Explanations include the in situ germination of tetraspores (allowing gametophytic thalli to be epiphytic on tetrasporophytes), the coalescence of spores or developing discs (resulting in chimaeras), mitotic recombination during cell division in the mature diploid thallus (resulting in patches of diploid male and female cells on the tetrasporophyte), a mutation eliminating the repression of female expression allowing haploid male plants to be bisexual and initial failure of cell walls to form during the development of tetraspores. Polyploids can be produced from plants with diploid gametangia. The sexes and phases are usually morphologically identical but gametophytes or their parts may be smaller. The growth rates of the sexes may differ and diploid juveniles may survive better than haploid. Neither polyploidy nor hybridization results in superior growth. The sex ratio is probably 1:1 but females may appear to be more abundant. Diploid and haploid phases are usually either about equal or diploids predominate, often depending on the type of substratum. At high latitudes reproduction peaks in late summer whereas in the tropics it may be high all year. In temperate regions growth rate is fastest and biomass highest in late summer; in the tropics peak biomass is mainly in the winter. Spermatia are effective for only a few h. Spores vary in size around 25 \m, diploid ones usually being larger. Cystocarps or tetrasporangia in the field may not currently be releasing spores. In the laboratory spore release shows a diurnal rhythm, peaking during the night or day according to the species. All the above attributes are potentially important in planning and executing Gracilaria cultivation.     

Population dynamics and culture studies of the edible red alga Callophyllis variegata (Kallymeniaceae)

Callophyllis variegata is a red alga that has been exported to Japan as an edible seaweed over the past few years. Available data strongly suggest that after a few years of exploitation of the C. variegata stands in southern Chile, a decline of its abundance seems to be occurring. However, there is not sufficient knowledge available to sustain harvesting strategies or to develop cultivation techniques. This study describes the C. variegata landings in the south of Chile and also provides some basic data on the biology of this species. Experiments related to the cultivation of early developmental stages, frond cultivation under controlled conditions and the regeneration capacity of the holdfast of this red alga are also presented. Spore production occurs mainly in autumn and winter and survival of carpospores decreased as the temperature increased from 8 to 12°C. Survival of tetraspores increased significantly, from 50 to 60% to over 80%, when temperature was raised from 8 to 12°C. Carpospore survival was also significantly affected by the photon flux density. This effect was mainly at 8°C, whereas at 33 µmol m^?2 s^?1 the survival of the spores is always low. The cultivation of apical portions of C. variegata under laboratory conditions showed that lower temperatures (8°C) significantly increased growth. Salinity and photon flux density did not have an effect on specific growth rate. Laboratory experiments demonstrated that holdfasts can regenerate fronds and that these fronds can be excised and cultivated, and are far more tolerant to environmental factors than the apical portions.     

Micropopulation differentiation in phenol content and susceptibility to herbivory in the Chilean kelp Lessonia nigrescenss (Phaeophyta,Laminariales)

Micropopulation differences in phenol content between intertidal and subtidal individuals of the kelp Lessonia nigrescens were found. Subtidal plants showed: (1) significantly higher phenol content than intertidal individuals, in vegetative and reproductive tissues, (2) intra-plant differences, with higher content in apical frond tissues, (3) higher resistance to consumption by herbivorous fishes. The microscopic progeny of subtidal plants showed the same trend as adult plants: (1) haploid spores from subtidal plants had higher phenol content than spores from intertidal individuals, and (2) the microscopic sporophytes derived from subtidal spores and gametophytes were less consumed by herbivorous snails (Tegula tridentata) than those derived from intertidal plant propagules. No increase in phenol content was detected after mechanical injury to experimental fronds, or after transplantation to the subtidal environment.In addition to the absence of inducible responses, the different phenol content between intertidal and subtidal individuals, in adult diploid plants and also in the haploid progeny, suggests that both environments differ someway enough to fix the mentioned features on the plants of Lessonia nigrescens. It is likely that the differences in herbivory between the two distributional extremes contributed to the observed pattern.     

Seasonality of red and green macroalgae from Antarctica—a long-term culture study under fluctuating Antarctic daylengths

Summary The seasonal development of the endemic Antarctic alga Palmaria decipiens (Palmariales, Rhodophyta) and of the Antarctic-cold temperate algae Iridaea cordata, Gigartina skottsbergii (Gigartinales, Rhodophyta), Enteromorpha bulbosa (Ulvales, Chlorophyta) and Acrosiphonia arcta (Acrosiphoniales, Chlorophyta) was monitored during two years in a culture study under fluctuating daylengths mimicking the conditions on King George Island (Antarctica). Temperature was kept constant at 0°C and nutrient levels were maintained at 0.6 moles m^–3 nitrate and 0.025 moles m^–3 phosphate. In P. decipiens, blades on germlings and on thalli from the previous season are initiated under Antarctic winter conditions and show maximum growth in October. Formation of blades on old thalli of I. cordata and G. skottsbergii started between June and August, maximum growth occurred in December. Sporangia started to form in G. skottsbergii in September and March and spore release was observed 9 months later at 27 mol photons m^–2s^–1. E. bulbosa and A. arcta grew optimally in November and December conditions. Spore or gamete release was observed in December and January in plants kept at 46 mol m ^–2 s^–1 and in January to March in plants kept at lower photon fluence rates, respectively. The minimum light requirements for completion of the life cycle were 31.4 mol m^–2 year^–1 in A. arcta, 47.1 mol m^–2 year^–1 in E. bulbosa and P. decipiens and 141.3 molm^–2 year^–1 in I. cordata and G. skottsbergii. These values suggest lower distribution limits of either 53±23 m, 49 ±22 m and 38±17 m in clear offshore waters or of 28 ±5 m, 26±5 m and 20±4 m in small inshore fjords of the Antarctic Peninsula region.Contribution No. 282 of the Alfred-Wegener-Institute für Polar-u. Meeresforschung     

Practical and descriptive techniques for Gelidium rex (Gelidiales,Rhodophyta) culture

Hydrobiologia - Research on the culture of Gelidium rex was approached from two points of view, growth of thalli from spores and growth from re-attachment. Mollusk shells, which are very easy to...     

Assessment of populations ofGracilaria chilensis (Graeilariales,Rhodophyta) utilizing RAPDs

Phenotypic variability and mixing of material due to massive cultivation for commercial purposes has contributed to the taxonomic confusion ofGracilaria in Chile. At least four species with cylindrical thalli and similar morphology have been recorded. However, since establishment ofG. chilensis, most of the collected thalli have been attributed to this species despite the lack of diagnostic features. In an attempt to resolve whetherGracilaria from 3 localities where it grows in natural and artificial populations belongs to the same species, gametophytic samples were compared by applying RAPD-PCR to their total DNA. This was analysed using 25 different 10-mer primers from which 21 revealed polymorphism within and between populations. Similarity matrices and cluster analyses were performed based on the presence/absence of bands representing fragments of DNA generated by random amplification. Similarity values between two of the populations were equivalent to those detected within a third, indicating the mixing of genetic material due to transplant between the two former localities. Similarities between samples of ChileanGracilaria andG. tenuistipitata from Sweden are considerably lower (0.45–0.53) than those between populations from Chile (0.74–0.88), confirming the existence of a single specific taxon,G. chilensis, in these three localities.     

Cultivation of Gracilaria on the sea-bottom in southern Chile: a review

This review contains information about the cultivation techniques, strategies, problems and new challenges faced as well as an economic analysis of the income-producing capacity of Gracilaria farming, considering the variability of environmental systems where this alga is cultivated in southern Chile. The development of Gracilaria farming in Chile was made possible by an increased market demand, as well as the existence of basic knowledge that permitted the management of wild stocks and the initiation of cultivation practices. Subtidal cultivation systems appear to be more productive than intertidal systems and are less susceptible to wave action than intertidal cultivation areas. In relation to farming practices, this difference implies that planting and harvesting methods and strategies vary between habitats where cultivation is being carried out on a commercial scale. Several problems such as the environmental impact of different cultivation methods adopted by the farmers, the management of contaminating organisms and strain selection appear to be important and new areas for future research. Finally, an analysis of the income-producing capacity indicates that environmental differences also have important consequences for the management strategies of Gracilaria cultivation.