Algae Production Biology and Species Live food aquaculture

Algae Production, Biology and Species Live food aquaculture training course www. aquatrain. org

Biology l Microalgae: microscopic single-celled eukaryotic planktonic algae ¡ To be magnified 100 – 400 X in order to recognize family ¡ Reproduction by cell division ¡ Some species have own movements by flagella, other drift passively ¡ Divided in 9 divisions according to pigment types etc. ¡ Photoautotrophic (also heterotrophic) organisms Live food aquaculture training course www. aquatrain. org

Photosynthesis As with all plants, algae photosynthesise, i. e. they convert carbon into organic matter. Light is the source of energy, which drives this reaction with wavelength and photoperiod the main factors. Photosynthesis: 6 CO 2 + 6 H 2 O = C 6 H 12 O 6 + 6 O 2 In the dark, algae shifts from photosynthesis to respiration, and the equation is reversed and glucose is needed for energy Live food aquaculture training course www. aquatrain. org

Growth dynamics Live food aquaculture training course www. aquatrain. org

Growth dynamics 1. Lag or induction phase This phase during which little increase in cell density occurs is relatively long when an algal culture is transferred from a plate to liquid culture. 2. Log or exponential phase: the cell density increases as a function of time according to a logarithmic function. 3. Phase of declining growth rate; cell division slows down when nutrients, light, p. H, carbon dioxide or other physical and chemical factors begin to limit growth. 4. Stationary plateau phase: the limiting factors and the growth rate are balanced, which results in a relatively constant cell density. 5. Death or "crash" phase: water quality deteriorates and nutrients are depleted to a level incapable of sustaining growth. Cell density decreases rapidly and the culture eventually collapses. Live food aquaculture training course www. aquatrain. org

Light Energy source Intensity; not to low, not to high (photo-inhibition) Fluorescent tubes emitting either in the blue or the red light spectrum are preferred, as these are the most active wavelengths for photosynthesis. Live food aquaculture training course www. aquatrain. org

Nutrients As the concentrations of cells in phytoplankton cultures are generally higher than those found in nature, algal cultures must therefore be enriched with additional nutrients and mineral to make up for the deficiencies in the seawater. Nutrients as nitrate and phosphate are important for synthesis of DNA Minerals, trace elements and vitamins are important for synthesis of pigments, enzymes etc. Live food aquaculture training course www. aquatrain. org

Criteria for choosing the right species Sufficient nutritional requirements for both the fish larvae and rotifers l Not poisonous for the predators l Sufficient cell size and digestibility in order to be filtered and digested by the rotifers l High reproduction rate, reliable and sustainable in standardized commercial growing systems l Live food aquaculture training course www. aquatrain. org

Information about species Different algal species are grown for different species of fish or shrimp depending on the culture technique. The typical species cultured are as follows; Shrimp culture Fish culture Tetraselmis chuii Tetraselmis suesica Nannochloropsis sp. Isochrysis galbana Chlamydamonas sp. Chaetoceros gracilis Monochrysis lutheri Nannochloris atomus Skeletonema sp Chrorella sp. Nannochloropsis oculata Spirulina platensis Pavlova lutheri Dunaliella sp. Pseudochrysis galbana Live food aquaculture training course www. aquatrain. org

Information about some microalgae species Prasinophyceae – greenish coloured algae Tetraselmis chuii l l l Large green flagellate, often used in larval rearing of shrimp, fish and shellfish Optimal salinity 15 - 36 0/00 Optimal temperature 15 33 C Typical densities in mass culture 300 -450 celles/ml Very high lipid content Live food aquaculture training course www. aquatrain. org

Prynesiophyceae – golden brown flagellate Isochrysis sp. Used especially as a primary algae in shellfish hatcheries l Size: 3 -5 um l Spherical to pear shaped l Isochrysis galbana tahition Size: 5 -6 um Prefer temperatures up to 30 C and high light intensities l High DHA level and is therefore used for growing rotifers l l Live food aquaculture training course www. aquatrain. org

Eustigatophyceae – greenish yellow algae Nannochloropsis l l l Live food aquaculture training course www. aquatrain. org Small green flagellate Size: 2 -4 um Used in rotifer production Popular as greenwater Keeps suspended in the water column High total lipid content and EPA level.

Bacillariophyceae - Diatoms Chaetoceros sp. • non-chainforming marine diatoms • golden brown, rectangular in shape • Size: 4 -6 um • Optimal temperature: 25 and 30 C • Optimal salinity: 17 and 25 ppt • Light intensity: 500 to 10, 000 lux Live food aquaculture training course www. aquatrain. org

Nutritional value in some species Live food aquaculture training course www. aquatrain. org

Summary algae species Live food aquaculture training course www. aquatrain. org