Live food aquaculture training course

1
Artemia Biology and Strains
2
Artemia as live food advantages

• It is the ability of the Artemia to form dormant
  embryos or cysts that makes the Artemia nauplii
  the most widely used food item for the culture of
  fish and shellfish larvae.
• After harvesting and processing, cysts are packed
  into cans or buckets and become storable 'on
  demand' live feed.

3
Artemia as live food advantages

• Resting cysts can be stored for years
• Live nauplii can be available within 24-36 h
• Security/backup at breakdown of rotifer cultures
• Tailor-made bioencapsulation according to the
  species nutritional requirements
• Robust upon variation in environmental parameters

4
Systematics

• Phylum Arthropoda
• Class Crustacea
• Order Anostraca
• Familiy Artemidae

5
Collection of cysts from the surface

• large amounts of cysts are produced and
  released when environmental conditions
  deteriorate
• the cysts float to the surface in large
  concentrations
• at this stage, they are harvested and dried for
  the aquaculture and aquarium industry by
  commercial companies

6
Dry resting cysts in diapause

• Dry resting eggs (cysts) has an inactive
  metabolism and the embryo do not develop further
  as long as the cysts are kept dry or under anoxic
  conditions
• Main techniques for terminating diapause are
  dehydration, freezing and treatment with hydrogen
  peroxide

7
Hydration and activation

• Upon immersion in seawater, the cysts hydrate and
  become spherical
• Embryo resumes its reversibly interrupted
  metabolism at a water content of 60

8
Cyst Hatching

• Outer membranes of the cyst burst after about 24
  hours
• Embryo leaves the cyst shelll surrounded by the
  hatching membrane

9
Parasol stage and hatching

• Pre-nauplius stage is developing into Instar I
  before hatching
• Emergence of hatching membrane
• Characheristics
• colored brownish-orange due to the presence of
  yolk
• three pairs of appendages
• antennae which have a locomotory function,
• sensorial antennulae
• rudimentary mandible
• an unpaired red ocellus is situated in the head
  region between the antennulae.

10
Stage Instar II (metanauplius)

• Second larvae stage Instar II,
• functional digestive system,
• ingest particles of 1-50 µm
• Is reached about 8 hours after hatching

11
Further development

• Undertakes about 15 molts until it reaches the
  10th instar, with the following differention
• the body elongates
• patricles is filtered and ingested by the setae
  of the antennae
• paired lobular appendages which will
  differentiate into the thoracopods are budding in
  the trunk-region

12
Sex differentiation at 10th Instar
Female
Adult female (1 cm)
Male
13
Reproduction
Extreme conditions Ovipary
Good conditions ovovivipary
Uterus filled with nauplii
Uterus filled with resting eggs
14
Cyst Biology

• Cyst shell consist of 3 layers
• Alveolar layer
• Protection against UV and mechanical disruption
• Can be removed by hyopoclorite (decapsulation)
• Outer cuticular membrane
• Protects embryo from larger molecules than CO2
• Embryonic cuticle
• Transparent and elastic layer, develops into
  hatching membrane during incubation

15
Different strains found all around the world
16
Variability between strains of Artemia

• Nutritional value
• Size and energy content
• Hatching quality (hatching rate nauplii/100
  cysts hatching efficiency nauplii/g cysts)
• Number of cysts/g
• Growth rate of nauplii
• Specific cysts characteristics

17
Size and energy content (I)

• Selection of strains with regard to mouth size
• Example of gape with length in cod (figure)
• Prey size to gape ratio varies between 0,4 to 1
  in cod

Puvanendran et al. 2004. Can. J. Zool.
821380-1389.
18
Size and energy content (II)
Size, individual dry weight and energy content of
Artemia instar I nauplii from different cyst
sources hatched in standard conditions (35g.l-1,
25C)
19
Growth of nauplii
Growth of Artemia nauplii from different cyst
sources under standard culture conditions (7
days, darkness, 10 instar I nauplii/25 ml,
35g.l-1, 25C, fed with Dunaliella viridis)
20
Specific cysts characheristics

• Generally three supplies of small cysts San
  Fransisco Bay, Great Salt Lake and Vietnam

21
Specific cysts characheristics (II)

• Supplies of large cysts San Fransisco Bay, Great
  Salt Lake, Russia and China

22
Size of nauplii after 24 h enrichment