Renato Westermeier

Red algal farming in Chile: a review

Abstract Production of seaweeds in Chile has fluctuated between 74,000 and 322,000 wet metric tons/year during the last 14 years, involving different species of Phaeophyta and Rhodophyta. Among Rhodophyta, the most important harvested species include the carrageenophytes Sarcothalia crispata, Mazzaella laminarioides, Gigartina skottsbergii, Chondracanthus chamissoi, and the agarophytes Gracilaria chilensis and Gelidium lingulatum. Other less important taxa are Gel. rex, M. membranacea, Ahnfeltia plicata, Ahnfeltiopsis furcellata, Porphyra columbina, Callophyllis variegata, Mastocarpus papillatus and Chondrus canaliculatus. Chilean production comes mainly from wild stocks, as at present, cultivation on a commercial scale is restricted to Gra. chilensis. Total landings of Gracilaria currently stand at 120,000 wet tons. Large-scale cultivated biomass of this species, on the other hand, has been the result of a sharp increase in the number of farms, from less than 10 in 1982 to almost 322 in 1996. A basic understanding of key biological and ecophysiological aspects, as well as the availability of propagation methods, permitted the development of large-scale Gracilaria farming operations. However, during the cultivation process, new problems arose for the farmers, such as abrupt production decline, pests and pathogens. Similar key knowledge is lacking for other Chilean Rhodophyta, which creates a bottleneck that prevents the development of seaweed farming activities other than Gracilaria. This situation prevails in spite of the growing pressure on wild stocks triggered by an increase in the demand for raw material by the industry, with the obvious danger of over-exploitation and the resulting collapse of fisheries. Taking the above into consideration, an effort has been made in recent years to provide the basic knowledge necessary for the management and cultivation of some of the most valuable seaweed resources in Chile. Thus, the main objective of this contribution is to summarize the present situation of red seaweed cultivation in the country. We will address this issue by reviewing the landing statistics of these resources, followed by a summary of recent information that favours cultivation. These include propagation methods, culture conditions and techniques, product quality, pest management, strain selection and the diversification of seaweeds currently exploited in Chile.

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.

Suspended farming of Gracilaria chilensis (Rhodophyta, Gigartinales) at Cariquilda River, Maullín, Chile

Abstract The algal genus Gracilaria has become the major source of commercial agar extraction in Chile. Recently G. chilensis Bird, McLachlan and Oliveira has been extensively cultivated in Southern Chile in response to wild crop deterioration. This paper evaluates the performance of this species under suspended cultivation, using ropes at two different depths. Treatments including different algal inoculum and harvesting methods were evaluated. Moreover, monthly thallus losses and epiphyte abundance were quantified. The highest biomass production was found in treatments placed at 0.5 m from the bottom. Factors such as light and water movement seem to regulate temporal patterns of biomass variation. Epiphytes exhibited a more marked incidence in the warmer months and were seen to be abundant in stands with a small algal inoculum. Finally, estimated yields of Gracilaria reach values close to 100 t·ha−1·yr−1 fresh weight. These data, together with small losses of algal thalli, suggest good economic opportunities for this suspension culture system.

Maullinia ectocarpii gen. et sp. nov. (Plasmodiophorea), an Intracellular Parasite in Ectocarpus siliculosus (Ectocarpales, Phaeophyceae) and other Filamentous Brown Algae

An obligate intracellular parasite infecting Ectocarpus spp. and other filamentous marine brown algae is described. The pathogen forms an unwalled multinucleate syncytium (plasmodium) within the host cell cytoplasm and causes hypertrophy. Cruciform nuclear divisions occur during early development. Mature plasmodia become transformed into single sporangia, filling the host cell completely, and then cleave into several hundred spores. The spores are motile with two unequal, whiplash-type flagella inserted subapically and also show amoeboid movement. Upon settlement, cysts with chitinous walls are formed. Infection of host cells is accomplished by means of an adhesorium and a stachel apparatus penetrating the host cell wall, and injection of the cyst content into the host cell cytoplasm. The parasite is characterized by features specific for the plasmodiophorids and is described as a new genus and species, Maullinia ectocarpii.

Phenology of Gigartina skottsbergii (Gigartinaceae, Rhodophyta) in Ancud Bay, southern Chile

This study reports the variations in biomass and reproductive phenology in a natural bed of Gigartina skottsbergii over a period of a year and correlates these variations with the abiotic factors solar radiation, number of daylight hours, water temperature and salinity. The results obtained show an annual production cycle with maximum biomass values in spring-summer, correlated with high solar radiation and to a lesser extent with salinity. Sexual reproduction was maximum in autumn-winter, correlated with low temperature and short-day conditions. The population showed a large gametophytic dominance according to size and biomass, which suggests that there is not ecological equivalence between the life history phases of the species. Finally, based on the results, a restriction of harvesting to spring-summer is suggested.

Sexual compatibility and hybrid formation between the giant kelp species Macrocystis pyrifera and M. integrifolia (Laminariales, Phaeophyceae) in Chile

Two species of giant kelp inhabit the coast of Chile: Macrocystis integrifolia and M. pyrifera, representing important economic resources. As part of our efforts to domesticate these kelps for mariculture, and to obtain superior cultivars, we studied their biological relationship. Hybridization experiments with clonal gametophyte cultures showed reciprocal cross-fertility and produced fertile hybrid sporophytes with intermediate morphological characters. This hybridization potential in the laboratory contrasts with the persistence of two morphologically well-defined sister taxa in natural habitats on the Pacific coast of South America. We conclude that M. integrifolia and M. pyrifera are conspecific and speculate that unknown mechanisms support the co-existence of two morphologically distinct taxa on the subspecific level.

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.

Biological bases for management of Iridaea laminarioides Bory in southern Chile

The harvest and export of Iridaea laminarioides Bory, the dominant species in the intertidal communities in southern Chile, have increased significantly in the last five years, reaching 15% of the total Chilean production of marine algae in 1985. Of this 15%, 48% is harvested from the X Region (SERNAP, 1985).

Limiting factors in optimizing seaweed yield in Chile

A number of factors influenced yield from natural beds of marine algae in Chile. These factors are related not only to biological and ecological knowledge of the algal resource, but also to external events, such as; (1) the pressure of international markets for raw material, (2) unemployment level of coastal workers, which increases the number of seasonal harvesters, (3) the low level of regulation enforcement along Chiles extensive coast, (4) the low level of education and income of algal harvesters, and (5) except for Gracilaria, the lack of a management plan for algal resources.

Variations of chemical composition and energy content in natural and genetically defined cultivars of Macrocystis from Chile

Seasonal and intra-thallus variations of energy content and chemical composition were assessed in an intertidal population of Macrocystis in southern Chile. Phylloid protein and lipid from cultured material were compared with seasonal variation in native Macrocystis. Furthermore, populations in northern and southern Chile and Falkland Islands were compared with various intra-/inter-cultivar genotypes of Chilean Macrocystis. Energetic values did not show seasonal or intra-thallus variations, with the exception of pneumatocysts, which had high levels of ash (49.9% DW) and low values of total energy (8.3% DW). Seasonal patterns were detected in protein and carbohydrate composition, with opposite trends. Likewise, holdfasts contained high amounts of protein (21.0% DW), and phylloids were high in soluble carbohydrates (4.5% DW). Lipids instead showed two peaks per year in an intertidal population and reached up to 0.4% DW. Alginic acid was the major organic compound in intertidal Macrocystis (46.8% DW), with differences on seasonal and intra-thallus levels. Mannitol content, in contrast, was erratic and lower than in other Laminariales (<5% DW). In general, protein and lipid content in our cultivars were 20% higher than in natural populations. Our experimental results indicate the possibility to manipulate the chemical composition of Macrocystis thalli through inter-/intra-specific crosses. This will be a basis, upon which selected genotypes can open new perspectives to Macrocystis mariculture industries in Chile.