Mass Production of Marine Macroalgae

Abstract

Macroscopic marine algae, or seaweeds, form an important living resource of the oceans as primary producers. People have collected seaweeds for food, both for humans and animals. They also have been a source of nutrient-rich fertilizers, as well as a source of gelling agents known as phycocolloids. More recently, macroalgae play significant roles in medicine and biotechnology. Today, seaweed cultivation techniques are standardized, routine, and economical. Several factors, including understanding the environmental regulation of life histories and asexual propagation of thalli, are responsible for the success of large-scale seaweed cultivation. Different taxa require different farming methodologies. During the last 50 years, approximately 100 seaweed taxa have been tested in field farms, but only a dozen are commercially cultivated today. Of these, only five genera (Laminaria, Undaria, Porphyra, Eucheuma/Kappaphycus, and Gracilaria ) represent around 98% of the world’s seaweed production.

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C Yarish and R Pereira. Mass Production of Marine Macroalgae. In Sven Erik Jørgensen
and Brian D. Fath (Editor-in-Chief), Ecological Engineering. Vol. [3] of Encyclopedia
of Ecology, 5 vols. pp. [2236-2247] Oxford: Elsevier.

Author's personal copy
Mass Production of Marine Macroalgae
R Pereira, Centre for Marine and Environmental Research – CIIMAR, Porto, Portugal
C Yarish, University of Connecticut, Stamford, CT, USA
ª2008 Elsevier B.V. All rights reserved.
Introduction
Macroalgae and Mariculture
Integrated Multitrophic Aquaculture
Conclusion
Further Reading
Introduction
This article deals with aspects of mass production of
marine macroalgae, also known as ‘seaweeds’. This term
traditionally includes only macroscopic, multicellular
marine red, green, and brown algae. Seaweeds are abun-
dant and ancient autotrophic organisms that can be found
in virtually all near-shore aquatic ecosystems and some
may attain a length of 50 m or more. Despite the variety of
life forms and the thousand of seaweed species described,
seaweed aquaculture is presently based in a relatively
small group of about 100 taxa. Of these, five genera
(Laminaria,Undaria,Porphyra,Eucheuma/Kappaphycus, and
Gracilaria) account for about 98% of world seaweed pro-
duction. The basic cultivation techniques of these genera
are described.
Macroalgae and Mariculture
Macroscopic marine algae (seaweeds or sea vegetables)
form an important living resource of the near-shore
environment. For millennia, people have collected sea-
weeds for food, fodder for animals, as well as fertilizers
and soil enhancers. More recently, seaweeds have become
important sources of various biochemicals, such as
phycocolloids, and are important in medicine and bio-
technology. We all use seaweed products in our daily life
in some way or other. For example, some seaweed poly-
saccharides (sometimes referred to as phycocolloids) are
used in toothpaste, soaps, shampoo, cosmetics, milk, ice
cream, processed meats and other foods, air fresheners,
and many other items. In many Asian countries such
as Japan, China, and Korea, they are dietary staples.
Seaweeds have also been gaining momentum as new
experimental systems for biological research and are
now being promoted in polyculture systems as an integral
part of integrated multi-trophic aquaculture (IMTA).
Traditionally, seaweeds were collected from natural
stocks or wild populations. However, these resources were
being depleted by overharvesting, so cultivation techniques
have been developed. Today, seaweed cultivation
techniques are standardized, routine, and economical.
Several factors may account for the success of large-scale
seaweed cultivation including the unravelling of complex
life histories, regenerative capacity of the thalli, prolific
spore production, and the understanding of environmental
interactions. Different taxa require different farming
methods. Although some seaweeds need one-step farming
through vegetative propagation, others need multistep
farming processes. The latter must be propagated from
spores and cannot survive if propagated vegetatively.
Eucheuma,Kappaphycus,andGracilaria are propagated vege-
tatively (one step), whereas Porphyra,Ulva,Laminaria,and
Undaria are started from spores.
Although large-scale open water cultivation of some
species has been carried out in many Asian countries,
other species are cultivated in tanks and ponds. For
example, Chondrus crispus Stackhouse has been mainly
cultivated in tanks in Canada. Gracilaria is being culti-
vated in tanks and raceways in Israel and in man-made
ponds in China, Taiwan, and Thailand. Tank cultivation
of some Eucheuma spp. was tried in Florida and other parts
of the world; however, it was economically unsuccessful.
Epiphytes, fouling, and critical nutrient requirements
caused serious problems. The major scientific challenges
for successful tank cultivation are: (1) site selection;
(2) tank design and construction; (3) knowledge of the
reproductive biology of the species; (4) selection of the
best strains; (5) control of the environmental variables
including temperature, pH or CO
2
availability, light and
salinity; (6) plant agitation to remove boundaries for
nutrient uptake; (7) seawater exchange/nutritional
requirements; and (8) stocking density. A critical review
of these factors may be found in the works of Craigie and
Shacklock (see the ‘Further reading’ section) which focus
on the cultivation of Chondrus crispus, the most success-
fully cultured seaweed species in tank-culture.
During the last 50 years, approximately 100 seaweed
taxa have been tested in field farms, but only a dozen are
being commercially cultivated today. Table 1 provides
production data for the top five taxa as of 2004. A brief
introduction to life cycles and cultivation techniques of
these species is presented in subsequent sections.
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Porphyra Cultivation
Porphyra has an annual value of more than US $1.3
billion and is considered the most valuable maricultured
seaweed in the world. According to the Food and
Agriculture Organization (FAO), nearly 1 397 660 metric
tons (mt) (wet weight) of Porphyra were produced through
mariculture. Porphyra has nearly 133 species distributed
all over the world, including 28 species from Japan, 30
from the North Atlantic coasts of Europe and America,
and 27 species from the Pacific coast of Canada and
the United States. Six species of Porphyra (namely
P.yezoensis Ueda, P.tenera Kjellman, P.haitanensis Chang
et Zhen Baofu, P.pseudolinearis Ueda, P.dentata Kjellman,
and P.angusta Okamura et Ueda) are usually cultivated in
Asia with the first three being the most commonly
cultivated.
Porphyra grows from 5 to 35 cm in length. The thalli are
either one or two cells thick, and each cell has one or two
stellate chloroplasts with a pyrenoid, depending on the
species. Porphyra has a biphasic heteromorphic life cycle
with an alternation between a macroscopic foliose thallus
(the gametophytic or haploid phase), and a microscopic
filamentous phase called the conchocelis (the sporophytic or
diploid phase). Porphyra reproduces by both sexual
and asexual modes of reproduction. In sexual reproduction,
certain mature vegetative cells of the thallus differentiate
into carpogonia, and others on the same or different thalli
differentiate into spermatangia. After fertilization by ame-
boid sperm, the resulting fertilized carpogonia divide to
form packets of spores called zygotospores (¼carpospores).
After release, the zygotospores germinate, usually on a
calcareous substrate, and develop into the filamentous ‘con-
chocelis’ phase. The conchocelis phase can survive in
adverse environmental conditions but eventually gives
rise to ‘fat filaments’, then conchosporangia, and finally
conchospores under the appropriate environmental condi-
tions. The conchospores germinate in a bipolar manner to
give rise to a chimeric thalli, thus completing the life cycle.
Asexual reproduction happens only in some species
(e.g., P.yezoensis), through formation of blade archeospores
(previously referred to as monospores). The conchocelis
serves as a perennating stage in nature. The conchocelis
can also be maintained in laboratory cultures for long
periods through vegetative propagation.
Cultivation of Porphyra began in Japan, Korea,
and China during the seventeenth century or possibly
earlier depending on folk-lore from each of those coun-
tries. Modern techniques for Porphyra cultivation were
introduced to these countries in the 1960s. The culture
methods of Porphyra in all countries are basically very
similar, with minor modifications, such as adaptations to
local growing areas and traditional practices of local farm-
ers. The cultivation technique involves four major steps
(Figure 1): (1) culture of conchocelis, fat filaments,
formation of the conchosporangia and production and
release of conchospores; (2) seeding of culture nets
with conchospores; (3) nursery rearing of sporelings; and
(4) harvesting.
Culture of conchocelis
In Asia, the culture of conchocelis starts around mid
spring (March/April). In nature, the conchocelis phase
grows within oysters, mussels, clams, or scallop shells.
However, in Japan, artificial substrata made of transparent
vinyl films covered with calcite granules, are beginning to
be used as substitute for mollusk shells. Usually, the
oyster shells or artificial shells are placed on the bottom
of shallow tanks filled with seawater for seeding to take
place (Figures 1a–1c).
Seeding may be accomplished by introducing
chopped pieces of fertile (ripe) Porphyra blades into the
seeding tank, which are removed after the release of the
zygotospores. The zygotospore suspension can be pre-
pared artificially by air-drying the fertile thalli
overnight and then immersing them in seawater for
4–5 h the next morning (this will induce mass shedding
of zygotospores) or by grinding the fertile blades and
separating the suspension of zygotospores by filtration.
The zygotospore suspension is then introduced into the
seeding tank, where the spores settle on the calcareous
substrate.
An alternative method, growing in popularity, is the
mass cultivation of conchocelis that is then seeded
Table 1 Production (metric tons) and value (thousand of US dollars) of the five most important seaweed genus produced by
aquaculture
Genus Production (mt)Value (10
3
USD)Three main producers
Laminaria 4 075 415 2 505 474.9 China (98.3%), Japan (1.2%), and South Korea (0.5%)
Undaria 2 519 905 1 015 040.5 China (87.1%), South Korea (10.4%), and Japan (2.5%)
Porphyra 1 397 660 1 338 994.7 China (58%), Japan (25.6%), and South Korea (16.4%)
Eucheuma and Kappaphycus 1 309 344 133 325.2 Philippines (92%), China (7.5%), and Tanzania (0.5%)
Gracilaria 948 282 385 793.7 China (93.7%), Vietnam (3.2%), and Chile (2.1%)
Total 10 250 606 5 378 629
Modified from Aquaculture production 2004 (2006) FAO Yearbook, Fishery Statistics, vol. 98/2. Rome: FAO.
Ecological Engineering |Mass Production of Marine Macroalgae 2237

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directly on calcareous substrates. The advantage of this
technique is the use of defined strains that give a more
consistent crop. In each case, the seeded substrates are
kept in large tanks (0.25–0.5 m deep). The shell substrates
are either hung vertically or spread across the bottom.
The conchocelis is allowed to develop during the rest of
the summer under low light levels (25–50 mmol photons
m
2
s
1
), at 16:8 h L:D and at 23 C.
Recently, bioreactors have been developed for the
culture of ‘free-living conchocelis’ of native North
American Porphyra species in laboratory. In this method,
clones of conchocelis are vegetatively propagated to
produce enough biomass for mass production of conchos-
pores. Large amounts of conchocelis can be produced and
maintained in bioreactors under controlled temperature,
light, photoperiod, and salinity. The conchocelis are
induced, in mass, to produce reproductive fat filaments,
forming conchosporangia and conchospores. The process
is less cumbersome and requires less labor. Mass release
of conchospores can be induced as needed and seeded
onto nets.
Control of conchospore formation and release
Conchospore formation and release usually requires a
particular combination of conditions such as nutrient avail-
ability, temperature, photoperiod and photon flux density,
depending on the species. Conchospore release is pro-
moted by stirring, using compressed air bubbling, or by
treating cultures with lower temperature seawater (18 C
from 20–22 C). For the latter treatment, conchocelis-
bearing shells are transferred to lower temperature sea-
water tanks 5–7 days before seeding. Replacing the
seawater in conchocelis culture tanks and adding vitamin
B-12 can also promote conchospore release. To inhibit
conchospore release, conchocelis tanks may be covered
by black vinyl sheets and the culture seawater maintained
calm with little, if any, aeration.
Seeding culture nets with conchospores
Although the traditional method of the cultivation of
Porphyra (natural seeding of conchospores on bamboo
sticks and nets) may still be practiced in some areas
(especially Japan), the bulk of nori produced in Japan,
(a) (b)
(d)
(c)
(e) (f)
Figure 1 (a–d) Culture of conchocelis on oyster shells and rotary wheels for seeding of nets. (e) Nursery culture of Porphyra in Japan
Ikada system. (f) Floating ‘A’ frame system in China. (a–d) Courtesy of M. Notoya. (e) Courtesy of I. Levine. (f) After X. G. Fei
2238 Ecological Engineering |Mass Production of Marine Macroalgae

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China, and Korea depends on artificial seeding of con-
chospores from hatchery grown conchocelis. In these
countries, ‘seeding’ commences in autumn when the
water temperature begins to decrease to 18 C but this
can vary depending upon species. The nets are tradition-
ally 1.8 m wide and 18 m long and made of synthetic twine
3–5 mm in diameter. The nets may have a mesh size of
about 15 cm. In Korea, nets 2 m 100 m are now being
routinely used in commercial cultivation. Artificial seed-
ing may be done outdoors in the sea or indoors in shallow
hatchery tanks. Outdoor seeding is carried out in nursery
grounds by setting up layers of (12–16) nets on support
systems. Hatchery-produced mature conchocelis (con-
chocelis that has gone through several developmental
phases including fat filaments and conchosporangia) on
shells or on artificial substrata are placed in plastic bags
and hung under the nets. The released conchospores float
on the water and are collected in the nets. Indoor seeding
may be done by fixing the net either over a rotary wheel
or a conveyor belt that is rotated in a seeding tank con-
taining mature conchospore inoculum from the free-
living conchocelis culture (Figure 1d). Another method,
popular in China, is the indoor seeding of nets that are
suspended in shallow seeding tanks about 25 cm in depth.
The conchospores are inoculated by re-circulating water
via a submersible pump that is in the tank.
Sporeling stage
The nets that are seeded with the conchospores are
stacked into bundles of four or up to 12–16 nets. These
stacks of layered nets are transferred to the sea for nursery
cultivation. In nursery culture, the nets are put into the sea
and carefully monitored for blade development. During
this early stage, the nets are raised out of the water daily to
expose the young thalli to air and sun (nursery stage). This
exposure is necessary to reduce fouling organisms
(e.g., other seaweed species or microscopic algae such as
diatoms). In Japan, a popular system, called the ‘Ikada’
system, is used for this process (Figure 1e). In China,
Professor X. G. Fei has developed a floating A-frame
system that can be easily raised and lowered for support-
ing nursery nets and controlling the degree of exposure
(Figure 1f). Once blades are 2–3 mm, the nets can be
transferred to the farm sites or frozen for later use. These
nets are initially air-dried to reduce the water content of
Porphyra to 20–40% and then are stored at –20 C. The
frozen nets can then be used to replace lost or damaged
ones. When nursery-reared seedlings are 5–30 mm in
length, they are ready for out-planting. Seedlings may be
separated from the bundles using one of three methods of
cultivation: fixed pole, semifloating raft, or floating raft
(Figures 2a and 3a). The fixed pole method is used in
shallow intertidal areas (Figure 2b). The floating type is
designed for deeper waters. Specially designed harvesting
boats lift the growing Porphyra nets (Figures 2a and 3b–3d).
The semifloating raft is a hybrid of these two methods and
is most suitable for areas that have extensive intertidal
zones as at the mouth of the Yantzee River Estuary in
China (Figure 2c and Figure 3a).
Harvesting and processing
The out-planted Porphyra seedlings are allowed to grow
to 15–30 cm in about 40–50 days before they are mechani-
cally harvested (Figures 3c and 3d). The remaining thalli
are allowed to grow and may be ready for a second
harvest after another 15–20 days. Several harvests may
be made from the same nets in one growing season as
archeospores from the thalli reseed the nets during the
growing season. Nets may be routinely harvested 6–8
times during the growing season (every 15–20 days),
with yields of more than 3300 standard sheets (approxi-
mately 20 cm 20 cm) per year.
Gracilaria Cultivation
The red alga Gracilaria contributes approximately 66% of
the total agar production, according to the most recent
estimates. This contribution is likely to increase as culti-
vation expands and technologies are developed to
increase the gel strength of Gracilaria. Although more
than 150 species of Gracilaria have been reported from
different parts of the world, the taxonomy of the genus is
still in flux. Gracilaria is widely distributed all over
the world, but most of the species are reported to be
from subtropical and tropical waters. Major Gracilaria-
producing countries are by far, according to 2004 FAO
data, Chile and China, followed by Taiwan, South Africa,
Namibia, the Philippines, and Vietnam. Morphologically,
the thallus of Gracilaria is cylindrical, compressed, or
bladelike and irregularly branched, giving a bushy
appearance. Gracilaria has a typical Polysiphonia-type or
triphasic life history. The male and female gametophytes
in the early stages appear identical without the aid of a
magnifying lens. Subsequently, the latter can be easily
identified by the presence of cystocarps, which appear as
distinct hemispherical lumps all over the thalli. The
cystocarp releases a large number of carpospores (2n)
that give rise to the tetrasporophyte plants (2n). Each
diploid tetrasporophytic plant is morphologically similar
to the haploid gametophytic plants (i.e., they are iso-
morphic). The tetrasporophyte phase produces haploid
tetraspores by meiosis within cortical sporangia. The
tetrasporangia ultimately give rise to tetraspores that
germinate into male and female plants, thus completing
the triphasic life cycle.
Gracilaria is cultivated commercially through a num-
ber of methodologies.
Site selection for Gracilaria seedling cultivation is cri-
tical. Sites should be located near seawater sources for
open water cultivation. For pond cultivation, sites should
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be located near both seawater and freshwater sources to
insure salinity control. Sites should also be protected from
strong winds. Gracilaria tolerate a wide range of salinities
(10–24 psu), but it is important to check other ecological
conditions such as temperature, light, and pH (>7.5–8.0).
Healthy branches of Gracilaria from natural stock must
be selected for successful farming. Thalli of Gracilaria are
usually vegetatively propagated for successful large-scale
production; however, in some instances spores (either
carpospores or tetraspores) may also be used to seed
substrates for some farms.
Cultivation methods
Gracilaria cultivation is mainly practiced in three different
ways: open water cultivation, pond culture, and tank
culture. Open water cultivation is practiced in estuaries,
bays, and upwelling areas. Gracilaria has been cultivated
in ponds on a large scale only in China and Taiwan.
High
tide
Low
tide
Fixed pillar Semifloating raft All-floating raft
Three types of Por phyra cultivation
Favorable tidal range for Porp hyra
High tide level
Favorable tide range
Semifloating raft
Floating frames
Bamboo tubes
Short pillars (50
cm)
Nets
Mooring rope
20–30
M60
M
25–30
M
6
M
5
4
3
2
1
0
Local
tide
range
Low tide
level
Low
tide
Low
tide
High
tide
High
tide
(a)
(b)
(c)
Figure 2 (a) Three types of nori culture. (b) Cultivation methodologies for Porphyra: Determination of tidal level for cultivation.
(c) Semifloating raft culture of Porphyra. (a) Modified from Tseng CK (1981) Marine phycoculture in China. Proceedings of the
International Seaweed Symposium 10: 123–152. (b, c) Courtesy of X. G. Fei.
2240 Ecological Engineering |Mass Production of Marine Macroalgae

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Ponds are generally located in areas not exposed to strong
wind, situated near the sources of both freshwater and
seawater. Several species of economically important mar-
ine organisms (e.g., shrimp, crabs, fish, and prawns) are
co-cultured in the same pond at the same time – a type of
polyculture integrated multitrophic system. The use of
tanks may provide the greatest productivity per unit area
and is more efficient than any other type of farming. In this
type of system, several steps can be precisely controlled
and managed to reduce the labor input, although this type
of system has high operational (especially energy) costs.
Tank systems may hold promise for the processing of
nutrient-enriched waters from fed aquaculture systems
(i.e., from finfish or shrimp aquaculture within an
integrated multitrophic aquaculture system). Figure 4
illustrates the most common cultivation techniques used.
Figures 4a–4d show the bottom stocking method with
rocky substrata, insertion of Gracilaria in soft sediment,
and bottom stoking with Gracilaria attached to a plastic
tube, usually filled with sand. Figures 4e–4g
show the method of Gracilaria cultivation attached to
ropes in long line systems or in raft systems. The FAO
has published several technical papers on Gracilaria
cultivation.
Eucheuma and Kappaphycus Cultivation
Eucheuma and Kappaphycus are important carrageeno-
phytes and account for over 80% of world’s carrageenan
production. These taxa are abundant in the Philippines,
tropical Asia, East Africa, and the Western Pacific region.
Of more than two dozen species known, only Kappaphycus
alvarezii (Doty) Doty (formerly known as Eucheuma cottoni
Weber-van Bosse) and Eucheuma denticulatum (Burman)
Collins et Hervey (formerly known as Eucheuma spinosum
[Sonder] J. Agardh) are of major commercial importance.
During the last 30 years, these species have been success-
fully introduced to more than 20 countries for
commercial cultivation. The thalli of Eucheuma and
Kappaphycus are cartilaginous, cylindrical to compressed,
and branched. Some taxa may be prostrate or erect in
habit. Gametophytic and sporophytic thalli have been
reported for many species. Fertile female thalli develop
distinct cystocarps, which appear as mammillate struc-
tures. The life cycle is triphasic (same as in Gracilaria) and
consists of three stages: tetrasporophyte (2n), gameto-
phyte (n), and carposporophyte (2n). The gametophyte
is dioecious. The male thallus produces ameboid sperma-
tia within spermatangia. The female thallus produces
many few-celled carpogonial branches in the cortex of
the thallus, of which the tip acts as the carpogonium or
receptor cell for the spermatia. Fertilization results in the
carposporophyte within the tissue of the female gameto-
phyte. The carposporophyte produces carpospores (2n)
mitotically that once released develop into the
tetrasporophyte phase. Subsequently, the tetrasporophyte
produces tetrasporangia, which undergo meiotic divisions
producing tetraspores (n). Upon their release, the tetra-
spores develop into male and female gametophytes, thus
completing the life cycle.
(a)
(c) (d)
(b)
Figure 3 (a) Installation of Porphyra nets on semifloating raft. (b) Korean style floating culture of Porphyra. (c, d) Harvesting boat for
Porphyra. (b) Courtesy of E. Hwang. (c, d) Courtesy of M. Notoya.
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The steps in the farming of these genera include:
(1) site selection, (2) selection of cultivation methodology,
(3) farm maintenance, and (4) harvesting and drying.
Site selection is very important. The site should be far
from sources of freshwater such as rivers, creeks, and
estuarine areas, as well as other sources of nutrient or
industrial wastes. The site should be protected from strong
tidal or wind-generated waves, which can destroy the
farm. A fixed, off-bottom monoline method is the most
popular and convenient method used. Floating methods
(raft or long lines) are used when space prohibits the use of
the off-bottom monoline method. Maintenance of the farm
consists of weeding, repair to the support system, replace-
ment of lost seedlings, and removal of benthic grazers.
Farm maintenance is a critical aspect of euchemoid
(¼Kappaphycus) cultivation. Usually, the plants are har-
vested after 6 weeks, when each seedling weighs up to 1 kg
(Figure 5).
Laminaria Cultivation
Laminaria japonica Areschoug (commonly called ‘kelp’) is
the most widely cultivated species that is primarily culti-
vated in China, Korea, and Japan. According to the FAO,
4 074 415 mt (wet weight) of Laminaria were harvested
globally in 2004, mainly through cultivation. China is
the largest producer of Laminaria, contributing over 4.0
billion kg wet weight. L. japonica grows well on reefs or
stones in the subtidal zone, at a depth of 2–15 m (some-
times up to 30 m). They prefer sheltered and calm seas,
rather than open waters. The thalli of the edible kelp
L.japonica are large, up to 2–5 m in length, but sometimes
may grow up to 10 m. The life cycle of Laminaria is well
understood. It consists of an alternation of generations
between a microscopic gametophytic phase and a very
large macroscopic sporophytic phase. In the field, the
frond (the sporophytic phase) usually matures during
spring and late autumn. The sporophyte releases the
zoospores that settle down on a substratum. They imme-
diately germinate and grow into microscopic male and
female gametophytes in equal ratios. Upon reaching
maturity, the filamentous male gametophyte releases
motile biflagellate sperm (from an antheridium) that fer-
tilize a large nonmotile egg that is extruded from the
oogonium. Within 15–20 days, young sporophytes
develop, thus completing the life cycle. In nature,
L.japonica is a biennial, and the frond reaches a harvest-
able size in about 20 months after germination. The
cultivation period can be reduced to as little as 8–10
months through a technique called ‘forced cultivation’.
As with Undaria (another species of kelp), the cultivation
of Laminaria consists of four phases: (1) collection and
settlement of zoospores on seed strings; (2) production
of seedlings; (3) transplantations and outgrowing of seed-
lings; and (4) harvesting (Figure 6).
Traditionally, the collection of zoospores is carried out
in spring or in some cases in early autumn when fertile
thalli are available and the water temperature increases or
(a) (b)
(c)
(d)
(e) (f)
(g)
Figure 4 (a–d) Bottom stocking of Gracilaria using direct and
plastic tube method. (a) Transplantation of rocky substrata with
attached Gracilaria to new sites. (b) Gracilaria attached to rocks,
with rubber bands for anchorage in soft sediments. (c) Insertion of
Gracilaria into soft sediments using a fork. (d) Gracilaria attached
to sand filled plastic tubes. (e–g) Attachment of Gracilaria to ropes.
(a–d) Modified from Santelices B and Doty M (1989) A review of
Gracilaria farming. Aquaculture 78: 98–133; Oliveira EC and Alveal
K(1990)ThemaricultureofGracilaria (Rhodophyta) for the
production of agar. In: Akatsuka I (ed.) Introduction to Applied
Phycology, pp. 553–564. The Hague, The Netherlands: SPB
Academic Publishing; from Critchley AT and Ohno M (eds.) (1997)
Cultivation and farming of marine plants. In: CD-ROM, Expert
Centre for Taxonomic Identification (ETI), University of Amsterdam,
Amsterdam, ISBN 3-540-14549-4. New york: Springer. (e–g) From
Critchley AT and Ohno M (eds.) (1997) Cultivation and farming of
marine plants. In: CD-ROM, Expert Centre for Taxonomic
Identification (ETI), University of Amsterdam, Amsterdam,
ISBN 3-540-14549-4. New york: Springer.
2242 Ecological Engineering |Mass Production of Marine Macroalgae

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decreases to about 15 C, depending upon the season. The
Chinese technique of intermediate nursery culture is
employed to bring the plants to a size of 5–10 cm before
transplanting to the nursery grounds (Figure 6f). The
seed string (after 30–60 days) may then be transferred to
the sea and fixed to rafts consisting of a series of bamboo
segments anchored to the bottom by ropes or long lines
(50 m). Another major enhancement in the cultivation of
L. japonica has been the raising of sporelings via the mass
culture of gametophyte clones. Female and male gameto-
phyte clones are mass cultured individually, followed by
the induction of gametogenesis for each phase. With
reared clones, mass quantities of sporelings (with desired
traits) can be successfully produced, thereby reducing the
need for long-term cultivation in temperature-controlled
greenhouses or environmentally controlled rooms. The
(a) (b)
(c)
(d) (e)
Figure 5 Aspects of Gracilaria,Eucheuma, and Kappaphycus cultivation on ropes. (a and b) Gracilaria attachment and insertion in
rope culture. (c) Open water cultivation of Kappaphycus and Eucheuma on monofilament long lines. (d and e). Open water cultivation
and harvesting of Kappaphycus. Courtesy of T. Chopin.
Ecological Engineering |Mass Production of Marine Macroalgae 2243

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sporelings are transplanted to the seed string and then
inserted within the braided long lines that are usually
50–100 m long (Figure 6a). Raft-supported long-line sys-
tems are of two types, namely the single-line (bamboo or
rubber tube) and the double-line raft system (Figures 6a
and 6b). Thirty or more sporelings (attached to the polye-
ster seed string) are transplanted to a 2 m (or shorter) piece
of rope. One end of the growing rope (containing the seed
string with sporelings) is attached at regular intervals
(50 cm) to the main support rope of a raft or long-line
system so that the culture rope hangs vertically (the stan-
dard Japanese drop-line system; Figure 6b).
Aside from light and water temperature, nutrients
(especially NO
3

–N) were found to be a limiting factor
Porous fertilizer jar
Porous fertilizer
cylinder
Young sporophytes
Rope
Anchor
Parallel
Upright
Perpendicular
Bamboo tube
(d)
(a)
(b)
(c)
(e)
(f)
Figure 6 (a) Single-line bamboo rafts and (b) double-line bamboo rafts. (a–c) Bamboo rafts used for culture of Laminaria in China.
(d) Long line with Laminaria after 8 months of growth in the Yellow Sea, China. (e) Long line with Laminaria in South Korea. (f) Young
sporophytes growing on long line. (a–c) Modified from Cheng TH (1969) Production of kelp. A major aspect of China’s exploitation of
the sea. Economic Botany 23: 215–236. (e) Courtesy of E. Hwang.
2244 Ecological Engineering |Mass Production of Marine Macroalgae

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in the culture of Laminaria. Traditional culture was often
limited to waters that were highly fertile, such as those
found in bays. As culture systems were moved away from
near-shore bays to offshore sites, the introduction of
commercial fertilizers (using porous fertilizer cylinders
that release nutrients gradually) has significantly
extended the kelp-growing area to these deeper oceanic
waters. Harvesting of L.japonica takes place during late
April to June depending on oceanographic conditions
(Figures 6d and 6e). The blades are cut from the cultiva-
tion ropes and washed in seawater to remove diatoms,
hydrozoans, and other attached organisms. Afterward, the
blades are dried naturally in the sun for several days on
any available surface. When weather conditions are unfa-
vorable for natural drying, oil-powered dryers may be
used.
Undaria Cultivation
The brown algal genus Undaria (another species of ‘kelp’)
is an important food delicacy in Japan and Korea (tradi-
tionally known as ‘wakame’). It is sold boiled or dried and
is especially appreciated as an ingredient for soybean
paste soup (‘misoshiru’) and seaweed salad. Undaria has
three species (Undaria pinnatifida [Harvey] Suringar,
Undaria undarioides [Yendo] Okamura, and Undaria peter-
oseniana [Kjellman] Okamura), and of these, U.pinnatifida
is the most important. The production of Undaria has
tremendously increased, since its cultivation started in
China, by 2000. According to the FAO data, 2 519 905 mt
(wet weight), valued at more than 1.0 billion USD, of
Undaria was produced globally through culture in 2004,
with 2 196 070 mt coming from China alone. In nature,
Undaria commonly grows in open seas or within bays on
the temperate coasts of Japan, Korea, China, and other
areas of the northwest Pacific which may have a rocky
substrate. Usually, the frond grows to a length of 1–2 m.
The life cycle of Undaria consists of a microscopic game-
tophytic phase and a large macroscopic sporophytic phase
and is essentially an annual species. Young fronds of
Undaria appear late in October to early November and
grow rapidly until early spring. The mature sporophytes
release zoospores that germinate on rocky substrata and
develop into male and female gametophytes. After ferti-
lization, the zygote develops into a sporophyte, thereby
completing the life cycle. The cultivation of Undaria
consists of four stages and is essentially identical to that
of Laminaria (Figure 7). It consists of collection of zoos-
pores and seedlings, culture of gametophyte germlings,
outgrowing of thalli, and the harvesting and processing of
the thalli.
The mature sporophylls are first partially dehydrated
to induce release of zoospores and are then placed in
culture tanks filled with seawater. Another seeding
process called the ‘free-living technique’ uses vegetative
gametophytes grown in flasks and is similar to the
Laminaria rearing technology of clonal gametophyte tech-
nology. The seeded twine (usually 50 m of seed string)
wrapped frames (Figure 7d) are removed from the seed-
ing tank and arranged vertically in a temperature-
controlled culture tank about 1 m deep. During summer
and early autumn, the zoospores develop into micro-
scopic gametophytes on the seeding frames that are
wrapped with the twine. The germlings are allowed to
develop to seedlings (2–3 cm) before removal and out-
planting along the open coast. The out-planting of nur-
sery-grown seedlings starts in autumn when water
temperature is about 20 C. The original seeding ropes,
which initially had seed string inserted within the braided
rope, are cut into lengths of 4–6 cm (with approximately
10 seedlings each) and inserted into the twist of the main
cultivation rope. They are then set into the sea using rafts
or long lines (Figures 7a–7c). Generally, Undaria reaches
a harvestable size about 3–5 months after it is transferred
to the sea when they reach a length of 0.5–1.0 m
(Figure 7e). After the rope is hauled up from the sea on
the boat, the cultivated thalli are cut from the rope with a
sickle. Each harvested frond is approximately 5 kg in wet
weight. The crop may be sold fresh, sun-dried, or artifi-
cially dried.
Integrated Multitrophic Aquaculture
The recently described concept of IMTA provides an
alternative approach for sustainable aquaculture.
Intensive culture of fish or shrimp is now being practiced
in many places as integrated units with seaweeds and
mollusk culture. In these IMTA systems, the extractive
components (seaweed and mollusks) extract their nutri-
ents from the effluents of the fed components (fish or
shrimp). Solar energy drives the productivity of these
IMTA systems. This approach, besides being a form of
balanced ecosystem management, prevents potential
environmental impacts from fed aquaculture. It also pro-
vides exciting new opportunities for valuable crops of
seaweeds. The seaweed IMTA component may include
species of Porphyra,Laminaria,Undaria, and Gracilaria.
Conclusion
Seaweeds are autotrophic organisms that use sunlight to
extract from the water dissolved inorganic nutrients and
produce biomass (the general functional principle of pri-
mary producers in an ecosystem). For that reason, besides
being a healthy and nutritious food, as well as the source of
compounds for other applications, seaweeds are crucial
Ecological Engineering |Mass Production of Marine Macroalgae 2245

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elements for sound ecosystem management. The sustain-
able exploitation of marine resources (e.g., fed aquaculture
of finfish and shrimp) will need to be balanced with the
establishment of mass production of seaweeds for the sus-
tainable growth of aquaculture in the twenty-first century.
Seaweed aquaculture already represents 23% of the
world’s aquaculture production, but ‘marine agronomy’ is
still in its infancy and seaweed potential is far from being
fully exploited.
See also: Mass Cultivation of Freshwater Microalgae;
Multitrophic Integration for Sustainable Marine
Aquaculture.
Further Reading
Akiyama K and Kurogi M (1982) Cultivation of Undaria pinnatifida
(Harvey) Suringar, the decrease in crops from natural plants following
crop increase from cultivation. Bulletin of the Tohoku Regional
Fisheries Research Laboratory 44: 91–100.
Aquaculture production 2004 (2006) FAO Yearbook, Fishery Statistics,
vol. 98/2. Rome: FAO.
Buschmann AH, Correa JA, Westermeier R, Herna´ ndez-Gonsa´ lez MC,
and Norambuena R (2001) Red algal farming in Chile: A review.
Aquaculture 194: 203–220.
Cheng TH (1969) Production of kelp. A major aspect of China’s
exploitation of the sea. Economic Botany 23: 215–236.
Chopin T, Yarish C, Wilkes R, et al. (1999) Developing Porphyra/salmon
integrated aquaculture for bioremediation and diversification of the
aquaculture industry. Journal of Applied Phycology 11: 463–472.
Craigie JS and Shacklock PF (1995) Culture of Irish moss.
In: Boghen AD (eds.) Cold-Water Aquaculture in Atlantic Canada,
2nd edn., pp. 363–390. University of Moncton, Moncton: Canadian
Institute for Research on Regional Development.
Critchley AT and Ohno M (eds.) (1997) Cultivation and farming of
marine plants. In: CD-ROM, Expert Centre for Taxonomic
Identification (ETI), University of Amsterdam, Amsterdam,
ISBN 3-540-14549-4. New york: Springer.
Critchley AT and Ohno M (2001) Cultivation and Farming of Marine
Plants. ETI World Biodiversity Database, CDROM Series.
http://www.eti.uva.nl/products/catalogue/
cd_detail.php?id=177&referrer=search (accessed December 2007).
Graham LE and Wilcox LW (2000) Algae. Upper Saddle River, NJ:
Prentice-Hall.
He P and Yarish C (2006) The developmental regulation of mass
cultures of free-living conchocelis for commercial net seeding of
Porphyra leucosticta from Northeast America. Aquaculture
257: 373–381.
Side view Top view
Culture rope
Weight
Vertical hanging, single line
Horizontal hanging, bamboo raft
Horizontal hanging, single line
(a)
Hanging rope
Culture rope
Cable rope
Anchor
(sand bag)
(e)
(d)
(c)
(b)
Figure 7 (a–c) Methods for Undaria cultivation. (d) Undaria spore collector. The frame is 50 cm 50 cm and synthetic seed string is
wound around the frame. (e) Open water cultivation of Undaria. (a–c) Modified from Akiyama K and Kurogi M (1982) Cultivation of
Undaria pinnatifida (Harvey) Suringar, the decrease in crops from natural plants following crop increase from cultivation. Bulletin of the
Tohoku Regional Fisheries Research Laboratory 44: 91–100. (e) Courtesy of E. Hwang.
2246 Ecological Engineering |Mass Production of Marine Macroalgae

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McHugh DJ (2003) A guide to the seaweed industry. FAO Fisheries
Technical Paper 441, 107pp. Rome: Food and Agriculture
Organization of the United Nations.
McVey JP, Stickney RR, Yarish C, and Chopin T (2002) Aquatic
polyculture and balanced ecosystem management: New paradigms
for seafood production. In: Stickney RR and McVey JP (eds.)
Responsible Marine Aquaculture, pp. 91–104. New York: CABI
Publishing.
Neish IC (2003) The ABC of Eucheuma Seaplant Production.
http://www.surialink.com/abc_eucheuma/index.htm
(accessed December 2007).
Neori A, Chopin T, Troell M, et al. (2004) Integrated
aquaculture: Rationale, evolution and state of the art emphasizing
seaweed biofiltration in modern mariculture. Aquaculture
231: 361–391.
Neori A, Troell M, Chopin T, et al. (2007) The need for a balanced
ecosystem approach to blue revolution aquaculture. Environment
49(3): 37–43.
Ohno M and Matsuoka M (1997) Cultivation of the brown alga Laminaria
‘Kombu’. In: Critchley AT and Ohno M (eds.) Cultivation and Farming
of Marine Plants, ETI World Biodiversity Database CD-ROM Series,
ETI Information Services Ltd., and Unesco. http://www.eti.uva.nl/
products/catalogue/cd_detail.php?id=177&referrer=search
(accessed December 2007).
Oliveira EC and Alveal K (1990) The mariculture of Gracilaria
(Rhodophyta) for the production of agar. In: Akatsuka I (ed.)
Introduction to Applied Phycology, pp. 553–564. The Hague, The
Netherlands: SPB Academic Publishing.
Oliveira EC, Alveal K, and Anderson RJ (2000) Mariculture of the agar-
producing Gracilarioid red algae. Review in Fisheries Science
8(4): 345–377.
Sahoo D and Yarish C (2005) Mariculture of seaweeds. In: Anderson RA
(eds.) Algal Culturing Techniques, pp. 219–238. Amsterdam: Elsevier
Academic Press.
Santelices B and Doty M (1989) A review of Gracilaria farming.
Aquaculture 78: 98–133.
Material and Metal Ecology
M A Reuter, Ausmelt Ltd, Melbourne, VIC, Australia
A van Schaik, MARAS (Material Recycling and Sustainability), Den Haag, The Netherlands
ª2008 Elsevier B.V. All rights reserved.
Introduction
The Metal Wheel – Material and Metal Ecology
Product Design and Fundamental Recycling
Optimization Models
Recycling 1153 ELVs – From Theory to Practice
Material and Metal Ecology
Further Reading
Introduction
‘Metals and materials’ are used in a wide range of pro-
ducts and applications ranging from consumer products
(cars, electronics, white and brown goods, etc.) to con-
structions (buildings, roads) and agriculture (fertilizers),
etc. The social and ecological value of the materials in
these applications is not only determined by the ‘in-use
value’ of these applications such as functionality, durabil-
ity, safety, reduced energy consumption, esthetics, etc.,
but also by the possibility of these materials to return from
their original application into the ‘resource cycle’ after
their functional lives/use at the lowest environmental
impact. The design of the product determines the selec-
tion of materials to be applied in the products as well as
the complexity of the material combinations and interac-
tions within this product (e.g., welded, glued, alloyed,
layered). These actions directly affect the recyclability
of the materials, that is, whether the material cycle can
be closed and whether one can speak of an industrial
ecological system.
Figure 1 indicates that the social/environmental value
of materials and metals can only be properly determined if
both the resource cycle and the ‘technology/design cycle’
are fundamentally understood and described, but more
important that tools are available to link these three inse-
parable disciplines. The interconnectivity between the
resource cycle (i.e., the primary and secondary material
cycles), the technology/design cycle (i.e., product design,
recycling technology, materials processing, etc.) and the
nature (social/environmental) cycle is depicted by Figure 1.
Nature cycle
society/environment
Resource cycle
- Energy
- Materials
(primary/secondary)
Technology and
design cycle
- Science
- Design
- Technology
Figure 1 Philosophy: toward sustainability and material and
metal ecology by linking the indicated cycles. Reproduced from
van Schaik A and Reuter MA (2004) The time-varying factors
influencing the recycling rate of products. Resources,
Conservation and Recycling 40(4), pp. 301–328, with permission
from Elsevier.
Global Ecology |Material and Metal Ecology 2247