DIATOMS AS FEED FOR AQUACULTURE
By John J. Perez C.
Greek diatomos, ‘cut in half ’
Pennate diatom
Pseudo-nitzschiaCentric diatomThalassiosira
siliceous hoops (girdle bands)
chlorophyll a, fluorescing red when illuminated with blue Light
Pores are species specific
Diatoms support the most productive fisheries
Crucial role of diatoms in the global carbon cycle
Thalassiosira pseudonana (34Mb)
Phaeodactylum tricornutum (27 Mb)
Fragilariopsis cylindrus (80 Mb)
Fragilariopsis cylindrus (Grunow in Cleve & Möller) W. Krieger in Helmcke & Krieger 1954
Pseudo-nitzschia multiseries (300 Mb)
Unique combination of genes and metabolic pathways distinguish diatoms
Enormous amounts of diversity encapsulated
within diatoms
Thalassiosira nordenskioeldii
Young auxospore of Pseudo-nitzschia multiseries
Two of the novel type of spores of Chaetoceros furcillatus
Thalassiosira taelata
http://www.aquatic.uoguelph.ca/Human/Research/ijkl/kaczmarskai.htm
Life in the ocean wavesCyanobacteria
Heterotrophic bacteriaArchaea
viruses
Eukaryotic phytoplankton
Protists
Benthic diatoms are the main food source for abalone post-larvae
monospecific cultures of benthic diatoms have successfully been employed as feed for the culture of abalone post-larvae
in Taiwan, abalone post-larvae grown in hatcheries are usually fed with natural populations of benthic diatoms, following the traditional method of using biofilms of
mixed benthic diatoms as the settlement substrata for abalone post-larvae in hatcheries
a photosynthetically active biofilm of diatoms, e.g. Gyrosigma spp
Biofilm of mixed centric diatoms
postlarvae of various abalone species have a better growth rate when fed with cultured diatoms than those fed with natural unknown species
of diatoms
Post Larval 'spat': After 2-3 weeks swimming around in the water column, the pelagic veliger larva loses its velium and metamorphoses into the post-larval stage (spat). It loses its positive phototaxis (movement towards the sunlight), moves down from the water surface, and settles on hard surfaces in intertidal and subtidal areas. Settlement is triggered by a chemical that is produced by Coralline algae and adult abalone. Abalone feed on Coralline algae and the presence of adults indicates a good habitat to live! The post-larva sheds its swimming hairs (cilia) and begins to develop the adult shell form. This is the first feeding stage where they start to feed on diatoms.
Carbajal-Miranda et al. (2005)
Navicula incerta
Amphiprora paludosa
Haliotis rufescens
Daume et al. (2000)
Navicula sp., N. jeffr
Cylindrotheca closterium
Cocconeis sp
Haliotis rubra Amphora sp.
Gordon et al. (2006)
Amphora luciae
Navicula cf. lenzii
Haliotis discus
Achnanthes longipes
Nitzschia spCocconeis p. Navicula britannica
Nitzschia ovalis
Kawamura et al. (1998)
Haliotis iris
Gallardo and Buen (2003)
Mixed diatoms vs. monospecific cultures of
Navicula
Haliotis asinina
little information concerning
diatoms as feed for Haliotis diversicolor
Kawamura et al., 1998
differences in the species of diatoms they have been fed
lipid, protein and extracellular polymeric substances (EPSs)
Poor and unpredictable performance of abalone postlarvae
Hypothetical cellular pathways and processes in iron-limited pennate diatom cells. All roman green or red type depicts gene transcripts found to be up- or down-regulated, respectively. Italicized and underlined green type indicates metabolites found to be enriched relative to total protein in iron-limited cells. DF, diffusion factor; EPS, extracellular polymeric substances; FR, ferric reductase; HMA, heavy metal-associated; PCD, programmed cell death; ROS, reactive oxygen species.
AIMS• to improve the growth and the survival of
abalone post-larval stages in a specific growth system using specific diatoms species
• a better understanding of their basic dietary requirements
farmers attempting to produce mollusks and crustaceans from the larval stage
• high cost of producing live food (microalgae)• up to 30% of the total cost of production
(Valenzuela-Espinoza et al., 1999).
Alternative
• use immobilized microalgae
• can be cheaper than algae produced by traditional methods
• ready for use (Chen, 2003).
Specific aims
• Survey the diversity of diatoms species found in H. diversicolor hatcheries.
• Isolate and develop a monoculture that could be immobilized and encapsulated in alginate beads for long-term storage as algal stock.
monospecific algal stocks used as feed for cultivating the post-larvae of H. diversicolor
• Lipids• Proteins• EPS – soluble EPS– bound EPS– internal carbohydrate– residual carbohydrate
Collection and preparatory cultures of benthic diatoms
Diatoms from small abalone hatchery ponds
scraped from abalone post-larvae settlement substrates (plastic plates)
collected in l L collection bottles
placed in a cool icebox
transported to the Algal Laboratory of the National Taiwan Ocean University, Keelung, Taiwan
Yean-Chang Chen, Ph.D.Associate Professor,
Department of Aquaculture,
National Taiwan Ocean University,
Keelung, TaiwanEmail:
[email protected]@ind.ntou.edu.tw
Tel: 886 2 24622192 ext. 5221Fax: 886 2 24633150====
Martek 120-liter photobioreactor
Deep aerated tank used for the culture of Nannochloropsis for aquaculture
Eicosapentaenoic acid (EPA, 5,8,11,14,17-cis-eicosapentaenoic acid)
• an n-3 C20-polyunsaturated fatty acid that is metabolically active.
20:5(n-3)
a carboxylic acid with a 20-carbon chain and five cis double bondsthe first double bond is located at the third carbon from the omega end.
with a double bond (C=C) starting after the third carbon atom from the end of the carbon chain.
EPA is an omega-3 fatty acid
EPA and its derivatives have proved beneficial in prevention and treatment of certain medical conditions
• coronary heart disease• blood platelet
aggregation• abnormal cholesterol
levels• several carcinomas
EPA is effective also in arresting and minimizing tumor growth
EPA is currently sourced from fish oil• No other sources are
commercially available. – fluctuates in price and quality. – contamination of fish oil with
pesticides and heavy metals.– an alternative economic and
consistent source of EPA is needed.
– Microalgae are one potential source.
Annual EPA demand
125 tones in Japan
demand is expected to increase dwindling supplies of
fish oil
Current market price of EPA ethyl ester (95% pure) about $650/kg