Shrimp feed

1. PRESENTATION
ON
MICRO-ALGAE

2. PREPARED
BY
MD. INJA-MAMUN HAQUE
ABDUR RAZZAK HASAN
TAHTEHAL ENAM BORNO

3.  The base of the food chain in the marine
environment comprises Phytoplankton
 Phytoplankton is the main producer in marine
enviornment
 Most frequently used in commercial culture
operations

4. What is micro-algae???
 commonly known as seaweed
• Also referred to as phytoplankton, microphytes, or
planktonic algae
 Produce mass quantities of zooplankton
(rotifers, copepods, brine shrimp)
 This zooplankton serves as food source for larval
and early-juvenile stages of crustaceans and fish

5. Major classes of
cultured algal species
 More than 40 different species isolated and
cultured as pure strains in intensive systems
 currently used
8 major classes and 32 genera

6. Diatoms
 Skeletonema costatum
 Thalassiosira pseudonana
 Chaetoceros gracilis
 C. calcitrans

7. Flagellates
 Isochrysis galbana
 Tetraselmis suecica
 Monochrysis lutheri

8. Class
 Cyanophyceae
 Bacillariophyceae
 Haptophyceae
 Chrysophyceae
 Prasinophyceae
 Cryptophyceae
 Xanthophyceae
 Chlorophyceae

9. Figure 2.2. Some types of marine algae used
as
food in aquaculture (a) Tetraselmis spp. (b)
Dunaliella spp. (c) Chaetoceros spp. (Laing,
1991)

10. A generalized set of
conditions for culturing
micro-algae
Parameters Range Optima
Temperature (°C) 16-27 18-24
Salinity (g.l-1) 12-40 20-24
Light intensity (lux) 1,000-10,000
(depends on volume
and
density
2,500-5,000
Photoperiod
(light: dark, hours)
16:8
(minimum)
24:0
(maximum)
pH 7-9 8.2-8.7

11. Temperature controlled room for maintenance of algal
stock cultures in a bivalve hatchery: stock cultures in
test tubes (left)
and inoculation hood (right).

12. AERATION/MIXING

13. Why mixing is necessary???
 To ensure all cells of the population equally
exposed to the light and nutrients
 To prevent sedimentation of the algae
 To avoid thermal stratification
 To improve gas exchange between the
culture medium and the air

14. Mixing achieved by
 stirring daily by hand (test tubes,
erlenmeyers), aerating (bags, tanks)
 using paddle wheels
 jetpumps (ponds)
NB: not all algal species can mixing tolerate
vigorous

15. Aeration filter (Fox, 1983)

16. Growth dynamics
Growth of an axenic culture of micro-algae
characterized by five phases
1. Lag or indution phase
2. Exponential phase
3. Phase of declining growth rate
4. Stationary phase
5. Death or "crash" phase

18. Lag or induction phase
 little increase in cell
density occurs
 relatively long when an
algal culture is transferred
from a plate to liquid
culture
 attributed to the
physiological adaptation of
the cell metabolism to
growth

19. Lag phase(Cont.)
 the increase of the levels of enzymes and
metabolites involved in cell division and
carbon fixation
 exponentially growing algae have short lag
phases, which can seriously reduce the time
required for upscaling

20. Exponential phase
key to the success of algal
production
 the cell density increases as a
function of time t according
to a logarithmic function
 Ct = C0.emt
 Ct and C0 being the cell
concentrations at time t and 0
 m =specific growth rate
(dependent on algal
species,light intensity and
temperature)

21. Phase of declining
growth rate
 Cell division slows down
when
 nutrients
 light
 pH
 carbon dioxide
 other physical and
chemical factors
begin to limit growth.

22. Stationary phase
 the limiting factor and the
growth rate balanced,
 results in a relatively
constant cell density

23. Death or "crash" phase
 water quality deteriorates
 nutrients are depleted to a
level
 incapable of sustaining
growth.
 Cell density decreases
rapidly
 Culture eventually
collapses.

24. Algal culture techniques

25. Algal culture techniques
Indoor Outdoor
 allows control over
illumination, temperature,
nutrient level,
contamination with
predators and competing
algae
 make it very difficult to
grow specific algal cultures
for extended periods

26. Algal culture techniques
Open Closed.
 uncovered ponds and tanks
(indoors or outdoors)
 are more readily
contaminated
 closed culture vessels such
as tubes, flasks, carboys,
bags, etc

27. Algal culture techniques
Axenic =sterile Xenic.
 free of any foreign
organisms such as
 bacteria and require a strict
sterilization of all
glassware, culture media
and vessels to
avoid contamination.
 impractical for commercial
operations

28. Advantages and disadvantages of
various algal culture
techniquesCulture type Advantages Disadvantage
Indoors A high degree of control
(predictable)
Expensive
Outdoors Cheaper Little control (less
predictable
Closed Contamination less likely Expensive
Open Cheaper Contamination more
likely

29. Advantages and disadvantages of
various algal culture
techniquesCulture type Advantages Disadvantages
Axenic Predictable, less prone to
crashes
Expensive, difficult
Non-axenic Cheaper, less difficult More prone to crashes

30. Advantages and disadvantages of
various algal culture
techniquesCulture type Advantages Disadvantages
Continuous Efficient, provides a
consistent
supply of high-quality
cells,
automation, highest rate
of
production over
extended
periods
Difficult, usually only
possible to
culture small quantities,
complex,
equipment expenses may
be high
Semicontinuous Easier, somewhat
efficient
Sporadic quality, less
reliable
Batch Easiest, most reliable Least efficient, quality
may be
inconsistent

31. Batch culture method

32. Batch culture method
 Consists of a single inoculation of cells into a
container of fertilized seawater
 Followed by a growing period of several days
 Finally harvesting when the algal population
reaches its maximum or near-maximum density
 In practice, algae are transferred to larger
culture volumes prior to reaching the stationary
phase

33. Batch culture method
 larger culture volumes are brought to a
maximum density and harvested
 The following consecutive stages might be
utilized: test tubes,
 2 l flasks,
 5 and 20 l carboys,
 160 l cylinders,
 500 l indoor tanks,
 5,000 l to 25,000 l outdoor tank

34. Batch culture method
 According to the algal concentration, the
volume of the inoculum amounts to 2- 10% of
the final culture volume
 Where small amounts of algae required
indoor culture employs 10 to 20 l glass or
plastic carboys (may be kept on shelves
backlit with fluorescent tubes)

35. Batch culture systems for the
mass production of micro-algae in 150 l
cylinders.

36. Batch culture method
ADVANTAGE
Batch culture systems widely applied because
of
 Simplicity and flexibility
 Allowing to change species
 To remedy defects in the system rapidly

37. Batch culture method
DISADVANTAGE
 Batch culture not necessarily the most efficient method
 harvested just prior to the initiation of the stationary phase
 must thus always be maintained for a substantial period of time past
the maximum specific growth rate.
 the quality of the harvested cells may be less predictable than that in
continuous systems
 need to prevent contamination during the initial inoculation and early
growth period
 require a lot of labour to harvest, clean, sterilize, refill, and inoculate the
containers

38. Batch culture method
Carboy culture shelf (Fox,
1983
Carboy culture apparatus
(Fox, 1983).

39. Continuous culture

40. Continuous culture
 Culture in which a supply of fertilized seawater
continuously pumped into a growth chamber
 The excess culture simultaneously washed out,
permits the maintenance of cultures very close to
the maximum chamber
 Two categorie
 Turbidostat culture
 chemostat culture

41. Continuous culture
turbidostat culture chemostat culture
 the algal concentration is
kept at a preset level
 by diluting the culture
with fresh medium
 by means of an automatic
system.
 a flow of fresh medium is
introduced into the culture
at a steady, predetermined
rate.
 The latter adds a limiting
vital nutrient (e.g.nitrate)
at a fixed rate
 in this way the growth rate
and not the cell density is
kept constant.

42. Continuous culture
Algae Culture density for
highest yield (cells per
μl
Usual life of culture
(weeks)
Tetraselmis suecica 2 000 3-6
Chroomonas salina 3 000 2-3
Dunaliella tertiolecta 4 000 3-4
Isochrysis galbana
Monochrysis lutheri
Pseudoisochrysis
paradoxa
20 000 2-3
Continuous culture methods for various types of algae in 40 l
internally-illuminated vessels (suitable for flagellates only) (modified
from
Laing, 1991),

43. Continuous culture
 Diagram of a continuous culture
apparatus (not drawn to scale):
 (1) enriched seawater
 medium reservoir (200 l);
 (2) peristaltic pump;
 (3)resistance sensing relay (50-
5000 ohm)
 (4) lightdependent
 resistor (ORP 12);
 (5) cartridge filter (0.45
 μm);
 (6) culture vessel (40 l);
 (7) six 80 W fluorescent tubes
(Laing, 1991).

44. ADVANTAGE
OF
Continuous culture
 Producing algae of more predictable quality
 Amenable to technological control and
automation

45. DISADVANTAGE
OF
Continuous culture
 Relatively high cost and complexity
 Requirements for constant illumination and
temperature mostly restrict continuous systems
to indoors
 This only feasible for relatively small production
scales.

46. Harvesting and preserving
micro-algae
 High-density algal cultures concentrated by either
chemical flocculation or centrifugation
 Products such as aluminum sulphate and ferric
chloride cause cells to coagulate and precipitate to
the bottom or float to the surface
 Recovery of the algal biomass is then accomplished
by
 1.siphoning off the supernatant
 2.skimming cells off the surface

47. Harvesting and preserving
micro-algae
 Coagulated algae no longer suitable as food for
filter-feeders
 Centrifugation of large volumes of algal culture
usually performed using a cream separator
 Cells deposited on the walls of the
 Centrifuge head as a thick algal paste
 The resulting slurry stored for 1-2 weeks in the
refrigerator or frozen

48. Harvesting and preserving
micro-algae
 Cryoprotective agents (glucose,
dimethylsulfoxide) added to maintain cell
integrity during freezing
 Cultures stored in hermetically sealed vials lose
their viability more rapidly than those kept in
cotton-plugged vials
 Concentrated cultures of Tetraselmis suecica kept
in darkness at 4°C maintain their viability

49. Nutritional value of
micro-algae
Depends on
 1. cell size
 2.digestibility
 3. production of toxic compounds
 4.biochemical composition
There marked differences in the compositions of
the micro-algal classes and species

50. Nutritional value
Protein 12-35%
Lipid 7.2-23%
Carbohydrate 4.6-23%

51. Use of micro-algae in
Aquaculture
Bivalve molluscs
 Intensive rearing of bivalves relied on the
production of live algae
 Comprises on average 30% of the operating
costs in a bivalve hatchery

52. use of micro-algae in
Aquaculture
Pinhead shrimp
 Added during the non-feeding nauplius stage
 algae available immediately upon molting
into the protozoea stage.

53. Penaeid shrimp
Requirements for cultured algae in hatchery
and
nursery culture of bivalve molluscs (Utting
and Spencer, 1991

54. Use of micro-algae in
Aquaculture
Marine fish
 "green water technique" part of the
commonly applied techniques for rearing
larvae of
 Gilthead seabream Sparus aurata
 Milkfish Chanos chanos
 Halibut Hippoglossus hippoglossus

55. Effects of the presence of
micro-algae
in the larval rearing tank
 stabilizing the water quality in static rearing
systems(remove metabolic by-products,
produce oxygen);
 a direct food source through active uptake by
the larvae with the polysaccharides present in
the algal cell walls possibly stimulating the
non-specific immune system in the larvae

56. Effects of the presence of
micro-algae
in the larval rearing tank
 an indirect source of nutrients for fish larvae
through the live feed (i.e. by maintaining the
nutritional value of the live prey organisms in the
tank)
 increasing feeding incidence by enhancing visual
contrast and light dispersion
 microbial control by algal exudates in tank water
and/or larval gut

57. Effects of the presence of
micro-algae
in the larval rearing tank
 an indirect source of nutrients for fish larvae
through the live feed (i.e. by maintaining the
nutritional value of the live prey organisms in the
tank)
 increasing feeding incidence by enhancing visual
contrast and light dispersion
 microbial control by algal exudates in tank water
and/or larval gut

58. References