Strain selection and physiology in the development of Gracilaria mariculture

Hansen, Judith E.

doi:10.1007/978-94-009-6560-7_13

“…The results from this study are important for potential commercialization, as algae from Site 2 had unusually large sizes and higher growth rates and would therefore be particularly suitable for use in aquaculture in Ireland. Similar phenotypic selection has previously led to the discovery of new, faster‐growing strains of commercial seaweeds (Neish and Fox 1971, Doty and Álvarez 1975, Doty 1978, Waaland 1978, Ryther et al 1979, Cheney et al 1981, Hansen 1984).…”

Section: Discussionmentioning

confidence: 92%

SEASONAL GROWTH AND PHENOTYPIC VARIATION IN PORPHYRA LINEARIS (RHODOPHYTA) POPULATIONS ON THE WEST COAST OF IRELAND¹

Varela-Álvarez

¹

,

Stengel

²

,

Guiry

³

2007

Journal of Phycology

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The phenology and seasonal growth of Porphyra linearis Grev. were investigated in two morphologically dissimilar populations from the west coast of Ireland. Thallus size and reproductive status of individuals were monitored monthly between June 1997 and June 1998. Both populations exhibited a similar phenology: gametophyte stages appeared on the shore in October, with spermatangial and zygotosporangial sori appearing the following February; the gametophyte stage began to degenerate in April and had disappeared completely by June. However, significant differences in growth and reproduction in the field and in cultures of plants from the two populations were observed. Thallus length and width of individuals from one population were significantly longer throughout the sample period, and reproduction and sporulation occurred 1 month earlier. Also, in situ relative growth rates (RGRs) of plants differed significantly and were correlated with different climatic factors (sunshine, day length, irradiance, rainfall, seawater temperature, and intertidal temperatures), suggesting that plants were affected by two different microhabitats. At one site, blades were more exposed to wave action, sunshine, and extreme minimum temperatures, while at the other site, blades were more protected in winter, spring, and early summer. In culture, RGRs of blades from the second site were higher than RGRs of blades from the first site under short days, corroborating the field results and suggesting a degree of phenotypic differentiation between the two populations. However, there were no sequence divergences of the RUBISCO spacer between strains of the two P. linearis populations.The genus Porphyra was first established by C. Agardh in 1824, and presently there are 267 species names in the AlgaeBase species data base, of which 113 are flagged as current (Guiry and Guiry 2006). These species generally occur intertidally or in the shallow subtidal attached to rocks and other seaweeds. Porphyra (known commonly as nori in Japan, zicai in China, and purple laver in Great Britain) is a major source of food for humans and is the most valuable seaweed grown by mariculture in the world today (Hanisak 1998). Several species of Porphyra occur along the North Atlantic coast of Europe, but none of these are currently grown under artificial conditions (Varela-Álvarez et al. 1999). If nori cultivation were to develop in Europe, one of the native species should be used. Porphyra linearis is a common winter alga in the high littoral and spray zones of northern Atlantic coasts (Bird 1973) and is considered a superior species with a pleasant flavor (McLachlan et al. 1971) and a higher protein content than other Porphyra spp. (McGregor 1992).Previous studies on the life history and phenology of putative P. linearis were conducted in Nova Scotia by Bird et al. (1972, Bird 1973 and in Port Erin by McGregor (1992). Bird et al. (1972, Bird 1973 observed that the first appearance of thalli in the supralittoral zone approximately coincided with a sea temperature of ...

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“…Pond and raceway culture (Shang, 1976;Chiang, 1981;Yang,1982;Friedlander and Lipkin,1982;Hansen, 1984;Rotmann, 1987).…”

Section: I Introductionmentioning

confidence: 99%

Sporulation, Pilot-Scale Farming, Agar Quality and Ecotypic Variation of the Agar Seaweed Gracilaria Sordida.

Intasuwan¹

0

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<p>The purpose of this study was to investigate the sporulation behaviour, the feasibility of farming in an open-water system, the quality and quantity of agar from a range of populations, and the genetic variation of the important agarophyte Gracilaria sordida W.A. Nelson (Gracilariales, Rhodophyta), which is widely distributed around New Zealand. The mean, total output of carpospores and tetraspores, and the periodicity of their release from G. sordida plants collected in the Wellington area, were measured under different levels of salinity, temperature, light intensity and daily exposure time to the air. The conditions that gave the greatest carpospore release were found to be approximately 15-35%. NaCl, l5-20' C, 50-200 uE.m-2 s-1 and 1-3 h daily exposure time. The conditions that gave the greatest tetraspore release were found to be approximately 15%. NaCl, l5-20' C, 150-200 uE.m-2 s-1 and 2-4 h daily exposure time. The diurnal periodicity of carpospore and tetraspore discharge based on hourly recordings was also measured. The peak rate of spore output occurred in the morning (7:00-8:00 hours) and in the late afternoon (16:00-17:00 hours). The carpospores and tetraspores not only had the same size but also showed the same germination pattern. A year-long pilot-scale farming project involving seeding the spores of sexually mature plants of G. sordida onto nets and ropes in Pauatahanui Inlet, Porirua Harbour, proved that this seaweed can be grown from spores on artificial substrates in field conditions. Of the artificial substrates tested, the best one for spore attachment was found to be polypropylene rope, and the relative growth rate on this substrate was maximal in spring (3.4%.d-1). The estimated production rate was 18.2 tonnes of dry weight per hectare per year. Problems encountered during field culture included epiphytes, sedimentation, storm damage and theft of floats and ropes. Yield and gel strength of agar extracts were studied from G. sordida collected in summer from 23 sites around the country. Native agar yield ranged from 17% to 32% (dry weight). The yield of native agar from cultured samples of these populations ranged from l0% to 29%. The yield of alkali-pretreated agar ranged from 9% to 24%. The gel strength of native agar ranged from 30 to 307 g.cm-2. Agar gel strength after alkali-pretreatment ranged from 230 to 625 g.cm-2. Native agar gel strength from cultured samples ranged from 177 to 342 g.cm-2. The gelling temperature of agar from wild populations ranged from 39 to 47' C for native agar and from 38 to 45' C for alkali-pretreated agar. The melting temperature of native agar ranged from 79 to 98' C. The melting temperature of alkali-pretreated agar ranged from 85 to 98' C. The maximum relative growth rate obtained from samples of G. sordida populations cultured in plastic bags was 6.2%.d-1, which was obtained from the Aramoana population. Starch gel electrophoresis of proteins was used to measure genetic variation in G. sordida. Protein extracts were prepared from 17 wild populations around New Zealand and from samples of these populations cultured in plastic bags. 20 isozyme loci were examined in G. sordida samples. Results indicated that G. sordida has low levels of genetic variation. Only two loci (Gd-1 and Pgm-1) of the 20 loci investigated were polymorphic (10%). Estimated heterozygosity of G. sordida was 0.011. There was no genetic variation between a native population and its cultured sample. The genetic distances between all populations were small. From the cluster analysis, all populations could be divided into two groups. Results indicated that populations were independent of each other, in which the effects of selection and genetic drift prevail. The buffer systems which gave the best protein resolution were Ridgeway (RW), Tris-EDTA-Borate (TEB) and Tris-Glycine (TG) and the enzyme which gave the best result in all buffer systems tested was Glucose-6-phosphate dehydrogenase (GD).</p>

show abstract

“…Pond and raceway culture (Shang, 1976;Chiang, 1981;Yang,1982;Friedlander and Lipkin,1982;Hansen, 1984;Rotmann, 1987).…”

Section: I Introductionmentioning

confidence: 99%

Sporulation, Pilot-Scale Farming, Agar Quality and Ecotypic Variation of the Agar Seaweed Gracilaria Sordida.

Intasuwan¹

0

View full text Add to dashboard Cite

<p>The purpose of this study was to investigate the sporulation behaviour, the feasibility of farming in an open-water system, the quality and quantity of agar from a range of populations, and the genetic variation of the important agarophyte Gracilaria sordida W.A. Nelson (Gracilariales, Rhodophyta), which is widely distributed around New Zealand. The mean, total output of carpospores and tetraspores, and the periodicity of their release from G. sordida plants collected in the Wellington area, were measured under different levels of salinity, temperature, light intensity and daily exposure time to the air. The conditions that gave the greatest carpospore release were found to be approximately 15-35%. NaCl, l5-20' C, 50-200 uE.m-2 s-1 and 1-3 h daily exposure time. The conditions that gave the greatest tetraspore release were found to be approximately 15%. NaCl, l5-20' C, 150-200 uE.m-2 s-1 and 2-4 h daily exposure time. The diurnal periodicity of carpospore and tetraspore discharge based on hourly recordings was also measured. The peak rate of spore output occurred in the morning (7:00-8:00 hours) and in the late afternoon (16:00-17:00 hours). The carpospores and tetraspores not only had the same size but also showed the same germination pattern. A year-long pilot-scale farming project involving seeding the spores of sexually mature plants of G. sordida onto nets and ropes in Pauatahanui Inlet, Porirua Harbour, proved that this seaweed can be grown from spores on artificial substrates in field conditions. Of the artificial substrates tested, the best one for spore attachment was found to be polypropylene rope, and the relative growth rate on this substrate was maximal in spring (3.4%.d-1). The estimated production rate was 18.2 tonnes of dry weight per hectare per year. Problems encountered during field culture included epiphytes, sedimentation, storm damage and theft of floats and ropes. Yield and gel strength of agar extracts were studied from G. sordida collected in summer from 23 sites around the country. Native agar yield ranged from 17% to 32% (dry weight). The yield of native agar from cultured samples of these populations ranged from l0% to 29%. The yield of alkali-pretreated agar ranged from 9% to 24%. The gel strength of native agar ranged from 30 to 307 g.cm-2. Agar gel strength after alkali-pretreatment ranged from 230 to 625 g.cm-2. Native agar gel strength from cultured samples ranged from 177 to 342 g.cm-2. The gelling temperature of agar from wild populations ranged from 39 to 47' C for native agar and from 38 to 45' C for alkali-pretreated agar. The melting temperature of native agar ranged from 79 to 98' C. The melting temperature of alkali-pretreated agar ranged from 85 to 98' C. The maximum relative growth rate obtained from samples of G. sordida populations cultured in plastic bags was 6.2%.d-1, which was obtained from the Aramoana population. Starch gel electrophoresis of proteins was used to measure genetic variation in G. sordida. Protein extracts were prepared from 17 wild populations around New Zealand and from samples of these populations cultured in plastic bags. 20 isozyme loci were examined in G. sordida samples. Results indicated that G. sordida has low levels of genetic variation. Only two loci (Gd-1 and Pgm-1) of the 20 loci investigated were polymorphic (10%). Estimated heterozygosity of G. sordida was 0.011. There was no genetic variation between a native population and its cultured sample. The genetic distances between all populations were small. From the cluster analysis, all populations could be divided into two groups. Results indicated that populations were independent of each other, in which the effects of selection and genetic drift prevail. The buffer systems which gave the best protein resolution were Ridgeway (RW), Tris-EDTA-Borate (TEB) and Tris-Glycine (TG) and the enzyme which gave the best result in all buffer systems tested was Glucose-6-phosphate dehydrogenase (GD).</p>

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Strain selection and physiology in the development of Gracilaria mariculture

Cited by 9 publications

References 10 publications

SEASONAL GROWTH AND PHENOTYPIC VARIATION IN PORPHYRA LINEARIS (RHODOPHYTA) POPULATIONS ON THE WEST COAST OF IRELAND¹

SEASONAL GROWTH AND PHENOTYPIC VARIATION IN PORPHYRA LINEARIS (RHODOPHYTA) POPULATIONS ON THE WEST COAST OF IRELAND¹

Sporulation, Pilot-Scale Farming, Agar Quality and Ecotypic Variation of the Agar Seaweed Gracilaria Sordida.

Sporulation, Pilot-Scale Farming, Agar Quality and Ecotypic Variation of the Agar Seaweed Gracilaria Sordida.

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Strain selection and physiology in the development of Gracilaria mariculture

Cited by 9 publications

References 10 publications

SEASONAL GROWTH AND PHENOTYPIC VARIATION IN PORPHYRA LINEARIS (RHODOPHYTA) POPULATIONS ON THE WEST COAST OF IRELAND1

SEASONAL GROWTH AND PHENOTYPIC VARIATION IN PORPHYRA LINEARIS (RHODOPHYTA) POPULATIONS ON THE WEST COAST OF IRELAND1

Sporulation, Pilot-Scale Farming, Agar Quality and Ecotypic Variation of the Agar Seaweed Gracilaria Sordida.

Sporulation, Pilot-Scale Farming, Agar Quality and Ecotypic Variation of the Agar Seaweed Gracilaria Sordida.

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SEASONAL GROWTH AND PHENOTYPIC VARIATION IN PORPHYRA LINEARIS (RHODOPHYTA) POPULATIONS ON THE WEST COAST OF IRELAND¹

SEASONAL GROWTH AND PHENOTYPIC VARIATION IN PORPHYRA LINEARIS (RHODOPHYTA) POPULATIONS ON THE WEST COAST OF IRELAND¹