Management And Conservation Of Seaweed Culture Environmental Sciences Essay
|✅ Paper Type: Free Essay||✅ Subject: Environmental Sciences|
|✅ Wordcount: 5320 words||✅ Published: 1st Jan 2015|
Seaweeds have been used practically in Chinese Herbs since 2700 BC in Emperor of Shen Nung. Reports show that since 300BC, seaweeds have been a part of the Japanese diet and mainly eaten in the Oriental countries like Japan, China, Korea and recently, in USA and Europe. Korea shows highest seaweed consumption per capita in the world.
The most valuable commercial use of seaweeds is as raw material for extraction of phycocolloids (agar, alginate and carrageenan), which are used in several industries. Seaweeds have been collected from natural stocks or wild populations. In fact, these resources were being depleted by over-harvesting and hence, the need for their cultivation. Today seaweed cultivation techniques are standardised, perfected and made economically favourable.
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Besides, industry prefers a greater stability through sustained supply of quantity and quality of raw materials. In order to prevent overexploitation of natural seaweed habitats and to meet the needs of industry in an uninterrupted manner, nearly all brown seaweeds, 63 per cent of red seaweeds and 68 per cent of green seaweeds are being cultivated. Top five cultivated seaweeds in the world are Laminaria, Porphyra, Undaria, Eucheuma and Gracilaria. These together account for 5.97 million metric tonnes of seaweed production.
Top 10 countries producing seaweeds are China, Korea, Japan, Philippines, Indonesia, Chile, Taiwan, Vietnam, Russia and Italy. The current phycocolloids (seaweed gels) industry stands at over US$ 6.2 billion. The world production of commercial seaweeds has grown by 119 per cent since 1984 and presently, 221 species of seaweeds are utilised commercially including 145 species for food and 110 species for phycocolloid production (Anonymous, 2003).
Japan leads the world in the production of agar and consumption. The world most successful seaweed cultivation industries are in Asia. Large-scale seaweed mariculture is only carried out in Asia. Cultivating nori was started in the 1697 in Tokyo Bay and the species is mostly cultivated in Japan. There are many different ways to cultivate seaweed. Cultivating seaweed has been done for a long time and has been cultivated in different ways. Management and conservation of seaweed is needed as seaweed production mostly depending on wild stock.
SEAWEED AND THEIR USES
Macroscopic marine algae, popularly known as seaweeds, form one of the important living resources of the ocean. It is a source of raw material of alginate, agar and carrageenan, gelatinous substances collectively known as hydrocolloids or phycocolloids. It is widely used in both food and non-food industries.
Hydrocolloids have attained commercial significance as food additives. The food industry exploits their gelling, water-retention, emulsifying and other physical properties.
The applications of alginate find place in frozen foods, pastry fillings, syrups, bakery icings, dry mixes, meringues, frozen desserts, instant puddings, cooked puddings, chiffons, pie and pastry fillings, dessert gels, fabricated foods, salad dressings, meat and flavour sauces.
Agar is used in foods such as confectionery, meat and poultry products, desserts and beverages and moulded foods. It is widely used in paper manufacturing, culture media, packaging material, photography, leather industry, plywood manufacturing, preservation of foodstuffs, cosmetics industry and pharmaceutical industry.
Carrageenan is also employed in food industry. Its value in the manufacture of sausages, corned beef, meat balls, ham, preparations of poultry and fish, chocolates, dessert gels, ice creams, juice concentrates, marmalade, and sardine sauces. It is also used in the manufacturing of non-food items like beer, air fresheners, textiles, toothpastes, hair shampoos, sanitary napkins, tissues, culture media, and fungicides. Carrageenan is used in salad dressings and sauces, dietetic foods, and as a preservative in meat and fish products, dairy items and baked goods.
Figure 1:Carrageenan seaweed
It is an alternative to animal-based gelatin in food industries used as enhancer, emulsifier, gelling, thickening, binding and stabilizing agent and also in non- food application such as dentifrice, pharmacology and industrial products. For example, some seaweed polysaccharides are employed in the manufacture of toothpastes, soaps, shampoos, cosmetics, milk, ice creams, meat, processed food, air fresheners and also animal feed, fertilizers for plants and source of various chemicals. In several oriental countries like Japan, China, Korea, etc., seaweeds are a staple part of the diet.
In the recent past, seaweeds have also been gaining momentum as new experimental systems for biological research and integrated aquaculture systems. Seaweed products are used in our daily lives in one or the other way.
PURPOSES OF SEAWEED MANAGEMENT AND CONSERVATION
Management and conservation of seaweeds is needed as seaweed resources are depletion over-time. Seaweed production mostly depending on wild stock and natural stock. Seaweed pollution also a major concern to consider in determine successful of managing coastal environment of the country. Seaweed grows out of control and caused pollutant to birds and marine life and further, leads to death of human when they consume of dangerous marine product.
SEAWEED AS USEFUL RESOURCES
Figure 2: Application of seaweeds
In the coast of Qingdao, East China, a huge blooms of seaweed covering some areas of sea. Local fishermen have been ordered to help clear the carpets of seaweed as it is believe would have to be treated as an obstruction to fishing vessels and other boats. It has resulted in increasing levels of pesticides and fertilizer entering the country’s waterways, providing a food source for the algae. Recent flooding caused by typhoons has also been causes (Anonymous, 2008).
Fishing vessels attempt to clear the green algae Workers bag up the seaweeds
Seaweed pollution in Qingdao
Figure 3: Seaweed pollution
3.2.1 FACTORS CONTRIBUTE TO SEAWEED POLLUTION
Seaweed pollution is definition given when seaweeds grow excessively in coastal ocean which may contribute harmful condition on seawater. Seaweeds blooming as a result of industrial, fertilizer and other sources input which run-off into coastal environment. The build-up of seaweeds will increase the photosynthesis and respiration processes which then lead to decomposing of organic matter. The decaying of dead seaweeds will produce hydrogen sulphide, a rotten and toxic gas to marine life and human as well.
Factors that may contribute to seaweed pollution in coastal ocean are stated as below:
Nitrates as fertilizer sources washed down from local cattle, pig and poultry farms
With increasing levels of pesticides and fertilizer entering the country’s waterways, it will providing a food source for the algae to bloom
Dumping of industrial waste and heavy metals in run-off areas such as leads and copper
Recent flooding caused by typhoons will increase the growth of algae in seawater column
And also combined with sunny weather enabled seaweeds build-up
3.2.2 EFFECT OF UNCONTROLLED SEAWEED GROWTH
Without proper management, seaweeds growth will cause many problems to environment especially marine lifes.
Difficult for vessel and boat passage in ocean water
Cut off access to food for local birds, fish and crustaceans
Death of marine life with depleted oxygen in the water
Further, hydrogen sulphide are produced by the decomposing seaweeds
Rotten smell and toxic will leads to death of individual life
4.0 PROBLEMS TOWARDS CONSERVATION OF SEAWEED
Unavailability of good quality seedlings – Inconsistency of the quality due to adulteration with foreign materials to the seaweed
Shortage of raw materials
Pollution in conservation areas (industrial waste etc.)
Lack of capital to venture into the industry
False cultivation method
Farmers are strongly urged to stop using raffia string for seaweed cultivation and replace them with nylon strings because using raffia string will affects the quality of carrageenan
Diseases affecting seaweeds (ice-ice)
Weather inconsistency (flooding, waves)
Unavailability of good quality seedlings
Lack of capital and R&D programmes
5.0 SEAWEED CULTIVATION
The cultivation of seaweed, principally for human consumption, is a traditional and still expanding industry in the east, especially in Japan, and increasing interest is being taken in the extension of these practices to other parts of the world for industrial as well as edible purposes. With supplies from certain naturally occurring resources failing to match rising demands and many of the world’s major untapped resources of seaweeds being remotely located, difficult of access or costly to harvest, cultivated raw materials almost certainly will become of increasing significance to processors of both edible and industrial products. Plastic bottles is a method that have been used in Sabah are used to keep seaweed called Euchema Kappaphychus Alverazii afloat.
Figure 4: Plastic bottle methods
Most seaweeds produce an enormous number of spores and they can be multiplied extensively if culture conditions are perfected. Such conditions depend upon attention to a number of factors. Care needs to be taken with the selection of protected habitats, free from pollution, and of suitable hydrographic environments; the algae need to be protected from predatory fish, sea urchins and other pests and parasites; transplanting of the germlings has to be undertaken with extreme care and harvesting carried out in such a way as to maintain peak productivity. In effect, a full knowledge of the plant’s biology and reproduction is a fundamental prerequisite to successful seaweed cultivation( Mathieson, 1973).
The most extensively cultured seaweed is Porphyra, the Japanese “nori”. Some 60 000 to 70 000 Japanese fisherman are now cultivating “nori” and producing the dried edible products which are very profitably marketed through a cooperative selling system. Porphyra culture in Japan dates back to the seventeenth century and the earliest cultural practices relied upon the positioning of tree (and later bamboo) twigs to capture the spores. Subsequently, nets became widely used as collecting agents instead of twigs and Conchooelis-phase of the Porphyra life-history.
This is a minutely filamentous, shell-boring stage which grows throughout the summer and which can be collected on oyster shells. In the autumn, when the temperature and light levels drop, the conchospores are liberated from the shells and attach themselves to a suitable medium (i.e., the collecting net) to grow into leafy thalli. The nets can thus be artificially “seeded” in tanks and then transported to the growing areas where they are attached to bamboo poles; about two months after budding the plants grow to between 15 and 20 cm in length and are then harvested.
Figure 5:Porphyra sp.
These and improved techniques (including freeze-drying of the thalli buds for storage) have resulted in marked increases in yields, in total output of “nori” and in profitability. Bardach et al. (1972) reported that in some areas up to 750 kg of “nori” can be obtained per hectare during the six to eight months’ growing season; the average production value of “nori” has risen from approximately U.S.$ 870 per ton in 1970 and 1971 to over U.S.$ 1 400 per ton in 1973, suggesting the possibility of gross earnings exceeding U.S.$ 1 000 per hectare. According to Suto (1974) “nori” farmers earn a “net income rate” of 60 to 70 percent, making Porphyra cultivation “the most profitable of all fisheries in Japan”.
The brown alga Undaria or “wakame”, is also extensively cultured in Japan. Two main systems are used – rope cultivation and stone “planting”. In the former method, strings of synthetic fibre are immersed in seaweed tanks with fertile Undaria weeds in the spring; enormous numbers of spores are released which adhere to the fibre. The fibres are lashed to frames and stored in tanks until late autumn when the young plants, having reached about 1 mm in length, are transferred to rafts in the sea.
The “wakame” grows quickly in the cold winter waters and is harvested when it has reached about 1 m in length. The amount of labour in “wakame” cultivation is much less than in “nori” farming; yields of about 10 kg of wet weed per 1 m of cultivating rope can be obtained in northern areas, about a half that yield in warmer districts (Suto, 1974). Where large quantities of Undaria are already growing “wild”, the planting of large stones or concrete blocks on the sea bottom has been found to help the attachment of the spores and the subsequent growth of the young plants.
Figure 6:Undaria sp.
Increasing amounts of Laminaria, or “kombu”, are also being cultivated in Japan, using similar stone planting and rope-culture techniques (MacFarlane, 1968). Laminaria culture, however, differs from the other two by the use of dynamite to improve the substrata and control harmful weeds (Wildman, 1974). Propagation of Laminaria has also been long practised in China. Druehl (1972) notes a unique Chinese method of fertilizing Laminaria through the use of porous, elongated earthenware bottles filled with nutrients and seawater which are placed, with young vegetative Laminaria plants, inside a basket-like structure made of bamboo poles and the whole suspended about 1 m below the sea surface.
Figure 7:Laminaria sp.
Some artificial propagation of Gelidium and other agarophytes is practised in Japan but it has not yet been possible to control the release of spores from these species as has been done with many other algae; moreover, the spores take two years to grow and reach harvestable size.
Figure 8:Gelidium sp.
A high valued species of Eucheuma have been introduced for cultivation or experimental purpose and where commercial quantities are currently being produced for the carrageenan industry such as Fiji, Philippines, USA (Hawaii, California, Florida), Kiribati (Christmas and Tarawa Islands), Tuvalu, Samoa, Malaysia, French Antilles, Tonga, Japan, Indonesia, Federal States of Micronesia, French Polynesia, Guam, China, Maldives, Solomon Islands, Tanzania, India, Cuba, Vietnam, Brazil, Venezuela, Kenya and Madagascar. However, introduction of exotics should not be done indiscriminately as it carries the risk of pathogen invasion, parasites, epiphytes and undesirable changes in the ecosystem.
Philippines is largely through the initiatives of one of the world’s largest phycocolloid manufacturers. The practical and economic feasibilities of culturing Eucheuma isiforme species in Florida have been illustrated by Dawes (1974) who considered two proposals, cultivation in natural sites (as in the Central Pacific) and in outdoor tanks. Dawes’ investigations indicated that tank culture would yield a much higher crop per unit area than mariculture in natural embayments. In the case of field culture, yields in the Florida Keys might average about 20 tons (4 tons dried, clean) Eucheuma per hectare but problems could arise from herbivores, storm damage and admixtures of other weeds; conversely, operating costs should be low. With controlled harvesting in culture tanks, Dawes postulated a potential yield of the equivalent of 243 tons dried, washed material per hectare; net profits, of course, must be considered in the light of tank construction, water movement costs, temperature control expenses, etc.
Figure 9:Eucheuma sp.
5.1 SEAWEED CULTIVATION IN MALAYSIA
Seaweed cultivation is one of Malaysia’s fastest growing sectors and is strongly supported by the government.
In the 9th Malaysian’s Development Plan, Sabah was mandated by the government to produce 250,000 metric ton seaweeds yearly by 2010. Currently, the state managed to produce 40,000 to 50,000 metric ton yearly only.
Singularly a Sabah product, main commercial species culture is Eucheuma cottonii. Environmental conditions around the Sabah coastline are generally favorable for culture of the species. Many of the operator there are Fillipino ancestry. Seaweed is sold as dried item. It take approximately 9 kg of seaweed to produce a kg of its dried form. Seaweed culture is low capital investment and has a fast turn over.
Figure 10:Seaweed Cultivation Project (Semporna)
In general according to report by DoF seaweed production still profitable from steady production volume recorded of recent (DoF, 2004a). Seaweed from Sabah is mainly for export market mainly to Denmark . Its dried form is sold directly to exporter without using any middlemen. Usually the later assists farmers by providing its aquaculture facilities hence an obligation to sell the product back. The price for a kg of dried form is about RM1.50. Of late however not many people wanted to get involved in the culture of seaweed because of better opportunities in other sectors. Beside price incentive, commercial production of it is quiet risky as the price is generally fluctuates and harvest largely depend on good sundrying condition. In addition future expend need to take into consideration of conflict with trees passing of fishing boats and promotion of tourism industry.
The international market is short of supply due to only up to 30% being produced for the world market. So far, South Korea, Mexico, Philippines, China and Japan are countries producing quality seaweed being ranked 15-30 pts for world market while seaweed produced in Sabah is ranked 30-45 pts.
Numerous annual production cycle. From planting till harvesting will take 45 to 60 days only. Thus volume will be substantial.
Figure 11:Seaweed cultivation in Malaysia
According to Barliotti and Silverthorne (1971), best period to harvest is Aug. to Nov. where agar content of the weed is at its highest, reproduction has already occurred and regeneration is at its maximum value
5.2 REQUIREMENT OF SEAWEED CULTIVATION
Choosing a site
Find suitable site for cultivating seaweed. A water temperature ranging form 25 °C to 30 °C is best for growing Eucheuma. Minimum water salinity required is about 28 ppt (parts per thousand) or more.
Figure 12: Seaweed should not be planted in front of a river mouth or in fresh water, as fresh water will kill the seaweed.
A white sandy bottom with the presence of a limited amount of natural seaweed, is probably the best place to cultivate Eucheuma. Eucheuma will not grow very well if the bottom is covered with seagrass because of food competition. A sea bottom with hard coral formations and coral heads also a muddy sea bottom is not a good site to establish farm.
Too many corals
Nice clean sandy bottom
Too many seaweeds
Moderate water movement is mostly preferred to strong water current. If the water current is too strong, it can damage plants and even wash away planted lines by pulling down the stakes. It will also slow down work as it is difficult work in areas with strong swift current. A constant exchange of ocean water with the changing of the tides and sufficient water movement as the one created by waves is needed. This will bring the necessary nutrients to the plants for a healthy growth. The direction that the water current flows is important for seaweed healthy.
Figure 14: Bad water flow: Seaweed farm set against water current. Strong water current can bend or even break the lines.
Figure 15:Good water flow: water current flows into the farm
Clear seawater allows sunlight to penetrate more easily to the plants. Seaweed planted close to the sea surface grows faster and healthier compared to that planted close to the sea bottom or in deep water.
Seaweed planted in shallow water near the surface (30 to 50 centimeters) receives plenty of sunlight and its growth will be good.
Seaweed planted in deep water (more than 1 meter from the sea surface) does not get enough sunlight and its growth will be poor.
It is important to consider the water depth while selecting the area of cultivation. At least knee deep water at spring low tide (0.5 meter) is the minimum water depth required to cultivate Eucheuma. In shallower waters seaweed can still grow, but it might be exposed to direct sunlight and wind. As soon as your seaweed is exposed to sun and wind, the tender tips of the plants are destroyed and if exposed for a long time (2 to 3 hours), the whitening of the branches can be seen. This will indicate that part of the seaweed has been killed. Eventually branches will break and drift away from the whitened area.
Too deep at spring low tide
Sufficient water depth at spring low tide
Too shallow at spring low tide
Turbid water (muddy) will not sustain good seaweed growth. Chemical pollution will kill the seaweed as in the case of most marine plants and animals.
There are at least 3 methods can use to cultivate seaweed such as Off-bottom (Fixed bottom method), Raft or Floating method and Longline method.
Wooden stakes are driven into the sea bottom 20 to 25 centimeters apart form each other in straight rows. The stakes should be 5 to 10 centimeter in diameter and 1 or 1.5 meter long. At least 0.5 meter of the stake should be driven into the sand to make them secure.
Figure 18:Seaweed line is typically suspended in the Off-bottom Method.
A 3 millimeter thick polypropylene rope 5 meters long is firmly stretched between two stakes. Attached to the 3 millimeter rope (line) are 30 pieces of raffia (polypropylene strings). Each of lanting material (seed), the size of the palm of your hand (150 grams), is tied to the raffia strings. The 3 millimeter rope, is suspended at least 20 to 30 centimeters from the sea bottom to prevent the growing seaweed from being tossed on the sand and 20 to 30 centimeters below the water surface at low tide to avoid the seaweeds from being exposed to direct sun light. Direct sun light will kill the exposed parts.
The raffia strings, should be 20 centimeter in length with both ends knotted to prevent fraying as shown in the previous photo. The raffia strings are firmly tied to a 3 millimeter rope in such a way that it will not move along the rope as the seaweed grows bigger, or during rough weather.
Prepare the lines as quickly as possible and place them in sea water. Seed will grow better if the time of seaweed kept out of the water is limited. Tie the raffia strings to lines on shore before tie seaweed seeds to them.
The off-bottom method can be prepare the lines either on shore, in the shallow water at low tide, or in punt near the farm.
Raft or Floating Method
In the floating method, seaweed is attached to some device that keeps the seaweed floating; rising and falling, with the tidal changes. Seaweed is keep about 50 centimeters below the water surface. The floating devise can be a simple frame made of bamboos, mangrove wood, or bush timber durable in seawater. Tie together four 2.5 meter long bamboos into a square frame and stretch 3 millimeter ropes (lines) inside the frame.
In a 2.5 meter square frame, stretch up to 15 lines, 10 to 15 centimeter apart. Each line will carry 15 pieces of seaweed tied to the 3 millimeter rope with raffia. In a frame like the one described, it can plant up to 225 pieces of seaweed.
In this method seaweed can be tied on shore by placing the raft on a support (oil drums or wooden posts).
Figure 19: Square floating frame built with mangrove wood.
The square floating frame, should be anchored to the sea bottom as shown in the figure. As the seaweed starts to grow and become heavier, the frame will sink. To avoid this, be sure to attach to the frame extra bamboos or floaters. Floaters can be simply made of styrofoam or bags filled with unhusked coconuts.
Figure 20: A floating frame with additional bamboo to assure sufficient buoyancy.
The longline method is similar to the raft or floating method in several ways. In fact, seaweed is hung to a rope which is suspended by floaters. In this method, however, the main rope is thicker; about 10 to 15 millimeters in diameter. This rope is tied to plastic floaters or bamboo set at 4 to 5 meters interval and anchored at each end. The pieces of raffia holding the seaweed, can be tied to the main rope in two ways.
Figure 21: Simplest way. The raffia string are directly tied to the main rope.
Additional pieces of rope, 0.5 to 1 meter long, can be tied to the main line and the raffia strings can be tied to them.
Seaweed has to be hung near the water surface to receive sufficient sunlight and can suspend the main line about 0.5 meter below the water surface.
As described in the first two methods, the lines can be prepared on shore. Tie seaweed seeds to the main line once the line is already stretched and suspended with floaters and prepare the lines from punt as shown in the drawing below.
Figure 23:Drawing of a longline being shot from a punt.
What are the advantages and disadvantages among these three culture methods?
Simple to construct
Difficult to locate a good area
Easy to manage
You might lose your crop during rough weather
You can prepare your lines on shore
You cannot move your farm if needed
Do not require much money to start
You might find more grazer fish around your seaweed
You can use local wood to prepare the stakes
You need to construct a drying rack
The farm is easy to reach at low tide
Raft or Floating Method
Can be utilized in shallow or deep waters
You might have difficulty finding bamboo
You do not need a sandy sea bottom bed
You need to find float materials
You can move your floating rafts if you need to
The frame might break or sink during rough weather
Most of the planting can be done on shore
The frame can be damaged by motor-driven boats
You do not need to construct a drying rack
You might need somebody to help you to handle the frame
You can use local wood to construct your frame
The seaweed seems to grow faster
You can set your longline almost anywhere
The ropes are costly
The seaweed seems to grow faster
Planting and harvesting cannot be easily done on shore
You can move the longline to another area
You need to buy expensive floaters
The longline can be damaged by motor-driven boats
Cover seaweed with tarpaulin or coconut leaves. Use styrofoam boxes to transport your seaweed. In this case, make a few holes on the upper edges of the box to facilitate aeration. Remember to keep the seaweed moist. Do not fill the box with seawater as this will make the seaweed rot rapidly unless the sea water is constantly circulated.
Seaweed farmers pouring seawater over a jute bag and a styrofoam box filled with seaweed.
Keep the seeds covered to protect them from direct sunlight. Pour some seawater over them at regular intervals. Preparing the lines from your punt, might take several hours and if not covered and kept moist, the seaweed seeds will be spoiled.
Disease and predators
During December to April, seaweed is more susceptible to diseases and is readily harmed by grazers. Also during this period, the growth of Eucheuma slows down and cyclones and bad weather may cause some damage to your farm. Drying in this period can also be difficult, as it is the wet season in Fiji.
As frequently observed, rabbit and puffer fish are the main seaweed grazers. In addition to these, sea urchins and sea turtles are also often seen damaging the seaweed plants.
After the warmer months, the rabbit fish grazing becomes a minor problem. In fact, rabbit fish move away from the seaweed. It is always a good idea to set your farm far away from coral heads, since these fishes normally live around the corals and move out to graze on seaweed.
Do not leave rubbish (tins, unused stakes, bits of wood, etc.) as these make a very good home for rabbit fish.
Whitened areas are more exposed to fungal infection. Especially during the warmer months, fungal infection can spread quite rapidly and the seaweed plants show large portions of discolored branches commonly seen as white and pink areas. “Ice Ice” is the common term used to describe seaweed plants in this condition.
Apart from occasional bad weather (rough sea and heavy rain), the effect of cyclones occurring during the summer months can be devastating. If a cyclone season is expected, harvest as much seaweed as you can and keep it on shore protected from wind and rain.
Put aside sufficient seaweed to allow you to re-start farming after the cyclone has passed by. Remember to keep this seaweed in bags moist with seawater at all times. That seaweed will be your re-planting material.
If seaweed is kept small during this period, and not allowed to become over-mature, little damage is expected. Decide to harvest after 4 or 5 weeks of growth instead of waiting for 6 or 8 weeks. Experience after going through several cyclones suggest that this strategy could limit your damage.
Also, be sure that stakes are firmly erected otherwise the strong water currents and swells during cyclones might wash away your effort.
After the cyclone has gone through, tangled lines should be entangled and secured again. Badly damaged seaweed should be completely removed and replaced with new seeds.
6.0 MANAGEMENT AND CONSERVATION OF SEAWEEDS
In the case of already heavily exploited resources, future potential has also to be considered in the light of the growing need, in some important cases, for management and protection. Some commentators (including Stanford, the discoverer of algin acid, as lo
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