Artemia culture

CULTURE OF
ARTEMIA
By
Dr. Varun Mishra
Ph.D. (Aquaculture)

INTRODUCTION
 Among the live diets used in the larviculture of fish
and shellfish, nauplii of the brine
shrimp Artemia constitute the most widely used
food item.
 Annually, over 2000 metric tons of
dry Artemia cysts are marketed worldwide for on-
site hatching into 0.4 mm nauplii.
 Indeed, the unique property of the small
branchiopod crustacean artemia to form dormant
embryos, so-called ‘cysts’, may account to a great
extent to the designation of a convenient, suitable,
or excellent larval food.

 Those cysts are available year-round in large
quantities along the shorelines of hypersaline lakes,
coastal lagoons and solar saltworks scattered over
the five continents.
 After harvesting and processing, cysts are made
available in cans as storable ‘on demand’ live feed.
 Upon some 24-h incubation in seawater, these
cysts release free-swimming nauplii that can
directly be fed as a nutritious live food source to the
larvae of a variety of marine as well as freshwater
organisms, which makes them the most convenient,
least labour-intensive live food available for
aquaculture.

 Artemia has been known to man for centuries, its use as
a food for the culture of larval organisms apparently
began only in the 1930’s, when several investigators
found that it made an excellent food for newly-hatched
fish larvae.
 During the 1940’s, most commercially available brine
shrimp cysts represented collections from natural saline
lakes and coastal saltworks. With the growing interest
for tropical hobby fish in the late 1940’s, commercial
value was attached to brine shrimp, thereby establishing
a new industry.
 Early pioneers exploited in 1951 the cyst production
of Artemia at the Great Salt Lake in Utah, USA. First
harvests of the lake yielded 16 tons of finished product.

 During the mid-1950’s, commercial attention for
brine shrimp was turned to controlled sources for
production in the San Francisco Bay region.
 It was found that brine shrimp and their cysts could
be produced as a by-product of solar saltworks.
 Since salt production entails management of the
evaporation process, yearly cyst and biomass
productions could be roughly predicted.

 In the 1960’s, commercial provisions originated
from these few sources in North America and
seemed to be unlimited.
 The expansion of aquaculture production in the
1970’s, the demand for Artemia cysts soon
exceeded the offer and prices rose exponentially,
turning Artemia into a bottleneck for the expansion
of the hatchery aquaculture of marine fishes and
crustaceans.
 In particular, many developing countries could
hardly afford to import the very expensive cy

 Genotypic and phenotypic variation (i.e. cyst size,
cyst hatching characteristics, caloric content and
fatty acid composition of the nauplii) determine.
 If a particular cyst product is suitable for hatchery
use of specific fish or shrimp species.

BIOLOGY AND ECOLOGY OF ARTEMIA
 In its natural environment at certain moments of the
year Artemia produces cysts that float at the water
surface and that are thrown ashore by wind and
waves.
 These cysts are metabolically inactive and do not
further develop as long as they are kept dry.
 Upon immersion in seawater, the biconcave-shaped
cysts hydrate, become spherical, and within the
shell the embryo resumes its interrupted
metabolism.

 After about 20 h the outer membrane of the cyst
bursts (“breaking”) and the embryo appears,
surrounded by the hatching membrane.
 While the embryo hangs underneath the empty
shell (“umbrella” stage) the development of the
nauplius is completed and within a short period of
time the hatching membrane is ruptured
(“hatching”) and the free-swimming nauplius is born

Harvesting of brine shrimp cysts from a saltpond

Cyst in breaking stage. (1) nauplius eye Embryo in “umbrella” stage
(left) and instar I nauplius
(right). (1) nauplius eye; (2)
antennula; (3) antenna; (4)
mandible.

 The first larval stage (instar I; 400 to 500 µm in
length) has a brownish-orange colour, a red
nauplius eye in the head region and three pairs of
appendages:
 The First antennae (sensorial function), the second
antennae (locomotory + filter-feeding function) and
the mandibles (food uptake function).

 The ventral side is covered by a large labrum (food
uptake: transfer of particles from the filtering setae into
the mouth).
 The instar I larva does not take up food as its digestive
system is not functional yet; it thrives completely on its
yolk reserves.
 After about 8 h the animal molts into the 2nd larval stage
(instar II). Small food particles (e.g. algal cells, bacteria,
detritus) ranging in size from 1 to 50 µm are filtered out
by the 2nd antennae and ingested into the functional
digestive tract.

 The larva grows and differentiates through about 15
molts.
 Paired lobular appendages are appearing in the
trunk region and differentiate into thoracopods .
 On both sides of the nauplius lateral complex eyes
are developing .
 From the 10th instar stage on, important
morphological as well as functional changes are
taking place: i.e. the antennae have lost their
locomotory function and undergo sexual
differentiation.

 In males they develop into hooked graspers, while
the female antennae degenerate into sensorial
appendages.
 The thoracopods are now differentiated into three
functional parts , namely the telopodites and
endopodites (locomotory and filter-feeding), and the
membranous exopodites (gills).

Instar V larva. (1) nauplius
eye; (2) lateral complex
eye; (3) antenna; (4)
labrum; (5) budding of
thoracopods; (6) digestive
tract.
Head and anterior thoracic region of
instar XII. (1) nauplius eye; (2) lateral
complex eye; (3) antennula; (4) antenna;
(5) exopodite; (6) telopodite; (7)
endopodite.

 Adult Artemia (1 cm in length) have an elongated
body with two stalked complex eyes, a linear
digestive tract, sensorial antennulae and 11 pairs of
functional thoracopods .
 The male has a paired penis in the posterior part of
the trunk region.
 Female Artemia can easily be recognized by the
brood pouch or uterus situated just behind the 11th
pair of thoracopods .
 Eggs develop in two tubular ovaries in the
abdomen. Once ripe they become spherical and
migrate via two oviducts into the unpaired uterus.

Head and thoracic
region of young male.
(1) antenna (2)
telopodite(3)exopodite
Posterior thoracic region, abdomen and
uterus of fertile female. (1) ripe eggs in
ovary and oviduct.

Head of an adult male. (1) antenna
(2) antennula (3) lateral complex eye
(4) mandible

 Fertilized eggs normally develop into free-
swimming nauplii (ovoviviparous reproduction)
which are released by the mother.
 In extreme conditions (e.g. high salinity, low oxygen
levels) the embryos only develop up to the gastrula
stage.

 At this moment they get surrounded by a thick shell
(secreted by the brown shell glands located in the
uterus), enter a state of metabolic standstill or
dormancy (diapause) and are then released by the
female (oviparous reproduction).
 In principle both oviparity and ovoviviparity are
found in all Artemia strains, and females can switch
in-between two reproduction cycles from one mode
of reproduction to the other.

 The cysts usually float in the high salinity waters
and are blown ashore where they accumulate and
dry.
 As a result of this dehydration process the
diapause mechanism is generally inactivated; cysts
are now in a state of quiescence and can resume
their further embryonic development when hydrated
in optimal hatching conditions.

 Under optimal conditions brine shrimp can live for
several months, grow from nauplius to adult in only
8 days time and reproduce at a rate of up to 300
nauplii or cysts every 4 days.
Artemia couple in riding position. (1)
uterus; (2) penis.

Detail of anterior thoracopods in adult
Artemia (1) exopodite
(2) telopodite (3) endopodite.
Uterus of oviparous Artemia filled with
cysts. (1) brown shell glands (darker
colour).

ECOLOGY AND NATURAL DISTRIBUTION
 Artemia populations are found in about 500 natural
salt lakes and man-made salterns scattered
throughout the tropical, subtropical and temperate
climatic zones, along coastlines as well as inland.
 This list still remains provisional as more extensive
survey work should lead to the discovery of many
more Artemia biotopes in different parts of the
world.
 The distribution of Artemia is discontinuous: not all
highly saline biotopes are populated with Artemia.

 Brine shrimp thrive very well in natural seawater,
they cannot migrate from one saline biotope to
another via the seas, as they depend on their
physiological adaptations to high salinity to avoid
predation and competition with other filter feeders.
 Its physiological adaptations to high salinity provide
a very efficient ecological defense against
predation, as brine shrimp possess:

 A very efficient osmoregulatory system.
 The capacity to synthesize very efficient respiratory
pigments to cope with the low O2 levels at high
salinities.
 The ability to produce dormant cysts when
environmental conditions endanger the survival of
the species.
 Artemia therefore, is only found at salinities where
its predators cannot survive (³ 70 g.l-1).
 As a result of extreme physiological stress and
water toxicity Artemia dies off at salinities close to
NaCl saturation, i.e. 250 g.l-1 and higher.

 As Artemia is incapable of active dispersion, wind
and waterfowl (especially flamingos) are the most
important natural dispersion vectors.
 The floating cysts adhere to feet and feathers of
birds, and when ingested they remain intact for at
least a couple of days in the digestive tract of birds.
 Consequently the absence of migrating birds is
probably the reason why certain areas that are
suitable for Artemia (e.g. salinas along the
northeast coast of Brazil) are not naturally inhabited
by brine shrimp.

 Next to the natural dispersion of cysts, deliberate
inoculation of Artemia in solar salt works by man
has been a common practice in the past.
 Since the seventies man has been responsable for
several Artemia introductions in South America and
Australia.
 Salt production improvement or for aquaculture
purposes.
 Additionally, temporal Artemia populations are
found in tropical areas with a distinct wet and dry
season (monsoon climate), through inoculation in
seasonal salt operations (e.g. Central America,
Southeast Asia).

LIFE HISTORY TRAITS AND REPRODUCTIVE CAPACITY-
 Life history and reproductive characteristics
of Artemia strains are important factors when an
introduction of brine shrimp in a new habitat is
considered.
 When competition with a local strain is to be
expected.
 These competitive abilities are related to factors like
the length of reproductive, pre- and post-
reproductive period, total life span, number of
offspring per brood, broods per female, time in-
between broods etc.

 In general New World (bisexual) populations have a
very large number of offspring per brood.
 A large number of offspring/day/female and a fast
development time to sexual maturity, which favours
this group to Old World bisexual and
parthenogenetic Artemia.

 Age at first reproduction is a key factor determining
the population growth rate, and the rate of
colonisation of new environments with limited
nutrient resources.
 If environmental preferences and nutritional factors
don’t interfere, New World bisexuals generally
outcompete parthenogenetic strains.
 The latter in their turn predominating over Old
World bisexuals.

 Inoculation experiments in natural habitats
therefore require prior screening of candidate
strains and of eventual local populations, as well as
the study of prevailing environmental conditions.
 Uncontrolled introduction of Artemia may thus lead
to a decrease of natural variability.
 Before inoculation of Artemia in a habitat with a
local strain is undertaken, sufficient cyst material of
the local population must be collected and stored in
order to safeguard its gene-pool.

NUTRITIONAL VALUE
 In the late seventies, when many fish and shrimp
hatcheries started to go commercial, switching from
one source of Artemia to another provoked
unexpected problems.
 Very significant differences in production yields
were even obtained with distinct Artemia batches of
the same geographical origin.
 Especially the pattern of total lipids and fatty acid
composition, as well as the metabolization of fatty
acids in the Artemia, seemed to differ widely from
strain to strain.

 Even from batch to batch, as a consequence of the
fluctuations in biochemical composition of the
primary producers (mainly unicellular algae)
available to the adult population.
 Cyst products from inland resources are more
constant in composition, be it however at
suboptimal low levels.
 Appropriate techniques have thus been developed
to improve the lipid profile of
deficient Artemia strains

 Taking advantage of the indiscriminate filter-feeding
behaviour of Artemia.
 Applying simple methods lipophilic compounds can
be easily incorporated in to the Artemia before
being offered as a prey .
 A number of other compounds also appear to be
variable from strain to strain.

 Nutritional components such as total amount of free
amino acids, pigments (canthaxanthin), vitamin C,
minerals and trace elements.
 Contamination with chemicals such as pesticides
and heavy metals.

Artemia culture

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