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In the last 10 years studies on the management and exploitation of Chilean carrageenophytes have proliferated in response to the increasing development of the local processing industry. One of the most important sources of raw material for Chilean carrageenan, Setchell et Gardner, was the subject of an intensive study to design a commercial cultivation technique which could be an alternative to wild harvest. In this context this pilot study reports the first successful attempt to culture from spores to harvestable plants. A three-step farming approach was developed: (i) seeding of spores onto scallop shells followed by a two-month nursery period in a greenhouse (until the development of initial upright thalli from the discoid crust occurred), (ii) outplanting juvenile plants on shells in the sea on a long-line system (until thalli attained 3–4 cm diameter) and (iii) detachment of fronds from the shells, fixing of individuals to vertical ropes and growth until commercial size was reached. Additional experiments to compare bottom and suspended growth, cultivation by fragmentation and whole fronds and meristematic activity of different zones of the fronds were performed. This study shows the technical feasibility of culturing from spores, complemented with growth of vegetative fragments, in order to optimize the management of the culture. In the future, therefore, it may be possible to replace the heavy exploitation of wild beds in southern Chile with farming activities.

The addition of low concentrations of commercial kelp extract (: Kelpak®) in addition to fertiliser has proven to be beneficial in agriculture. It triggers rooting in field crops, increases yields and has other useful effects, such as parasite reduction. Its efficacy has been attributed to the fact that Kelpak® is produced by a cold process, and is a high auxin/low cytokinin product. The aim of this study was to investigate if seaweeds (which do not have a root system) grown in culture systems, would benefit from the addition of Kelpak® or a combination of Kelpak® and fertilizer. A preliminary laboratory experiment was carried out by growing excised 15mm tips of the red alga in culture dishes containing Provasoli Enriched Seawater medium to which various concentrations of Kelpak® were added. tips in some of the Kelpak® treatments (1:2500; 1:1000; 1:500) grew significantly better than the control. Further experiments were carried out on a pilot commercial scale at Jacobsbaai Sea Products Ltd. on the South African west coast. was grown in effluent from fish (turbot) culture, with additions of 1:5000, 1:2500 and 1:500 concentrations of Kelpak® once a week. The intermediate Kelpak® concentration (1:2500) produced the highest growth of in the turbot water, while the highest Kelpak® concentration (1:500) inhibited growth. In another experiment, various combinations of aquaculture effluent water, commercial fertiliser and Kelpak® at 1:2500 were used. Best growth of was obtained in turbotwater containing both fertiliser and Kelpak®. The results suggest that Kelpak® could be useful in commercial seaweed mariculture operations.

Regulations of the Alaska Department of Fish and Game require that all fisheries in the state have a harvest management plan. In southeast Alaska two species of floating kelps, and , have been commercially harvested since 1992 for use as agrochemicals by the Alaska Kelp Company. However, there is currently no harvest management plan for this fishery. The lack of a formalized management plan is one factor that has kept the kelp industry from expanding in the state. We have employed an aerial digital multispectral imaging system (DMSC) calibrated with ground truthing for performing such an assessment. The system can be flown at varying altitudes to achieve spatial resolutions ranging from 0.5 to 2 m. Rapid ground truthing techniques were developed using morphometric measurements to predict biomass. Analysis of the DMSC imagery showed that good correlations could be developed between the multispectral imagery and kelp biomass estimates collected at the ground-truth sites. Repeatable estimates of kelp bed area derived from the multispectral imagery could be made at varying tidal levels. However, broad scale maps of kelp biomass suitable for estimating harvest rates could not be made at different tide levels. Multispectral imagery suitable for this purpose must be collected at a standard tidal level.

is an economically important kelp in South Africa. The harvested kelp is used mainly as feed for cultured (abalone) on farms all along the South African South and West Coast. The effects that different harvesting methods have on the growth of sub-canopy kelps, kelp population structure and kelp recruitment were tested in a kelp bed at Bordjies Rif near Cape Town. Two 30 × 10 m sites were set up, about 100m apart, in near monoculture stands of . Each 30 × 10m area was subdivided into three treatments. In treatment 1 (T1) the whole ‘head’ of each kelp sporophyte that reached the surface was cut off between the bulb and the primary blade (‘lethal’ method). In treatment 2 (T2) (‘non-lethal’ method), the secondary fronds of all sporophytes that reached the surface were cut 20–30 cm from their junction with the primary blade, and removed. In the control plot, the kelp plants were not treated. Harvesting treatments were done approximately every four months, at low spring tide, from 3 March 2003 to 3 November 2003 (three treatments). The effects of harvesting on the kelps depend largely on the size of plant and the time the fronds were removed; however, no seasonal pattern could be observed. The different treatments had no effect on the growth rate, population structure or recruitment of the kelp. This means that factors other than light play an important role in the growth, structure and recruitment of the kelp beds in False Bay. Results are discussed in relation to current commercial harvesting practices.

In South Africa, more than 7000 t (f wt) of kelp () fronds are harvested annually to feed cultured abalone. and are conspicuous red algal epiphytes on older kelps and provide habitat and food for numerous animals. Over 4.5 y, we examined the effects of one destructive harvest of on these 3 epiphytes. Two 20 × 20m plots of kelp with similar epiphyte loads were demarcated. In one, all sporophytes with stipes longer than 50 cm were harvested. The other plot served as a control. After 2.5 y the biomass of in the harvested plot had recovered to control levels, but the epiphyte load (g epiphytes. kg kelp) was statistically lower in the harvested plot after 2.5 and 3.5 y, and only recovered after 4.5 y. While most commercial harvesters cut through the “heads” (primary blades) of the kelp, effectively killing them, a new, non-lethal method removes secondary blades 20–30 cm from their bases, leaving the meristems and primary blades intact. At 5 sites studied, and were found almost entirely on stipes and primary blades, and harvesting only distal parts of secondary blades limited losses to about 50% of biomass. To protect epiphytes, non-lethal harvesting is recommended and permanent non-harvest zones have been established in addition to limiting kelp yields and disallowing harvesting in Marine Protected Areas.

Shoots and clumps of shoots of the commercial brown seaweed (“rockweed”) add to the benthic complexity of the intertidal environment, providing an important habitat for invertebrates and vertebrates. To protect the structure of this habitat, management plans for the rockweed harvest of southern New Brunswick include restrictions on gear type and exploitation rates limited to 17% of the harvestable biomass. However, owing to physical and environmental factors, the harvest is not homogeneous, creating patches of exploitation ranging from 15 to 50%.

A direct relationship existed between clump vulnerability, weight and length in a controlled harvest at 50% exploitation within 8m by 8m plots. At this exploitation rate, the gear rarely impacted clumps below 50 g or 60 cm in length. Clumps larger than 300 g and 130 cm were reduced by up to 55% of their length and 78% of their biomass. The overall impacts of the harvest on intertidal habitat is however of short duration as biomass recovers after a year of the experimental harvest. The rapid recovery is mostly due to a stimulation of growth and branching of the suppressed shoots of the clumps. Some harvested plots showed biomass even higher than initial levels, suggesting an increase in productivity at least during the first year after the harvest.

The chemical structure, gel properties and biological activity of the carrageenans isolated from cystocarpic and sterile plants of were investigated. The total carrageenan content of the sterile plant was observed to be twice that of the cystocarpic plants. According to data obtained by C-NMR and FT IR, the gelling polysaccharides from cystocarpic and sterile plants of have similar structures and were identified as -carrageenans. The difference between these polysaccharides was in the ratio of the - and -segments, with a predominant content of -segments in cystocarpic plants (80%). Moreover, KCl-insoluble fractions possibly contain hetero-disperse precursor: amounts of this in the polysaccharide from sterile plants were more than that extracted from the cystocarpic plants. The KCl-soluble fractions (non gelling) were -carrageenans with another carrageenan type that had a lowamount of 3,6-anhydrogalactose. Carrageenans from cystocarpic stages showed good gelling properties, whereas those from sterile plants formed a very weak gel. Structural differences and molecular weight of carrageenans obviously determine the biological activity of the polysaccharides. Non gelling-carrageenans from both types of plants showed high macrophage-phosphatase activity and -carrageenan from cystocarpic plant possessed a potent anti-coagulant activity, which was extremely strong in a low concentration of 100g mL.

Specificities of actions of fucoidanases from the marine microorganism KMM 3296 and the marine mollusk were studied. The enzymes possess similar specificities and catalyze the cleavage of accessible -(1→3)-fucoside bonds in fucoidans with highly sulfated -(1→4; 1→3)-L-fucooligosaccharides. A high degree of sulfation of the fucose residues in fucoidans makes -(1→3)-L-fucoside bonds inaccessible for the action of the studied enzymes. The maximum degree of cleavage of fucoidan was achieved by the fucoidanase from the marine bacterium KMM 3296.

Marine filamentous fungi (103 strains) isolated from various marine habitats were studied for their ability to produce extracellular O-glycosylhydrolases. Cultural filtrates of these strains were shown to contain a series of glycanases (laminarinases, amylases, cellulases, pustulanases) and glycosidases (-glucosidases, N-acetyl--glucosaminidases, -galactosidases, -mannosidases). Two species of marine fungi from different habitats were chosen for isolation of laminarinases and detailed study on enzyme properties. The fungus associated with the alga C. Agardh was collected near the Kuril Islands, and was sampled from bottom deposits of South China Sea. Properties of extracellular laminarinases were similar: temperature optimums (40–45 °C), molecular masses (54–56 kDa), K (0.1–0.3 mg mL). Temperature stability of laminarinase of was significantly higher than those from . It is shown that these enzymes are specific to -1,3-bonds in glucans, release predominantly glucose from laminaran and do not catalyze reaction of transglycosylation. Accoding to these data enzymes are exo-1,3--D-glucan-glucanohydrolases (EC 3.2.1.58). Inhibitor analysis demonstrated the significant role of tryptophan and tyrosine residues in the catalytic activity of enzymes. Molecules of laminarinase contained the functionally important thiol group.

The proximate chemical composition (ash, soluble carbohydrate, lipid and protein) was determined in 30 common species of tropical Australian marine macroalgae from Darwin Harbour (12°26′S, 130°51′E), in summer (hot and wet) and winter (cool and dry). There was a wide diversity of species in both seasons (19 species in summer and 20 species in winter). In most species, the major component was soluble carbohydrate (chlorophytes range 2.5–25.8% dry weight (dw), phaeophytes range 8.4–22.2% dw, rhodophytes range 18.7–39.2% dw) with significantly higher ( < 0.05) percentages only in winter season rhodophytes. Highest percentages of protein were found in rhodophytes collected in the summer (range 4.8–12.8% dw), with significantly lower percentages (< 0.05) during winter. All species had lipid contents within the range 1.3–7.8% dw, with highest percentages in summer phaeophytes, but no significant differences between species or season. Most species had moderate to high ash contents (24.2–89.7% dw), with the highest percentages during summer. Compared with summer samples, macroalgae collected in winter had higher energy value and slightly lower percentages of inorganic matter. The variation of algal groups and chemical composition may influence the availability of the food source for the majority of herbivores, which in turn is likely to effect their ecology and community structure.