Tiến Sĩ Optimisation of Artemia biomass production in salt ponds in Vietnam and use as feed ingredient in lo

LUẬN ÁN TIẾN SĨ (Thesis submitted in fulfilment of the requirements for the degree of Doctor (PhD) in Applied Biological Sciences)

OPTIMISATION OF ARTEMIA BIOMASS PRODUCTION IN SALT PONDS IN VIETNAM AND USE AS FEED INGREDIENT IN LOCAL AQUACULTURE ( Sản xuất tối ưu hóa sinh khối Artemia trong ao muối ở việt nam và sử dụng như thành phần thức ăn trong nuôi trồng thủy sản địa phương)

TABLE OF CONTENTS
Chapter 1 General introduction 1
Chapter 2 Literature review 7
Chapter 3 Culture of Artemia biomass
Section I Effect of partial harvesting strategies on Artemia biomass production in salt
works . 31
Section II Effect of different food supplements on proximate compositions and
Artemia biomass production in salt works 47
Secttion III Effect of different ratios of N:P on primary productivity: its combination
with feeding strategies for Artemia biomass production in salt ponds 69
Chapter 4 Drying Artemia biomass
Section I Total lipid and fatty acid contents of Artemia biomass dried using different
drying techniques 109
Section II Effect of solar drying on lipid and fatty acid composition of dried Artemia
biomass 117
Chapter 5 Application of Artemia biomass for target aquaculture species
Section I Formulated feeds containing fresh or dried Artemia biomass as live food
supplement for larval rearing of black tiger shrimp, Penaeus monodon 151
Section II Effect of fishmeal replacement with Artemia biomass as protein source in
practical diets for the giant freshwater prawn Macrobrachium rosenbergii
. 141
Section III Effect of different forms of Artemia biomass as a food source on survival,
molting and growth rate of mud crab, Scylla paramamosain . 157
Section IV Substituting fishmeal with Artemia meal in diets for goby
Pseudapocryptes elongatus: effects on survival, growth and feed
utilization . 173
Chapter 6 General discussion and conclusions 207
Chapter 7 References . 216
Summary/Samenvatting 239
Curriculum vitae 247

General introduction
Populations of the brine shrimp Artemia (Crustacea, Anostraca) are typical inhabitants of
extreme environments, such as hypersaline inland lakes, coastal lagoons, and solar salt
works, distributed all over the world, and characterized by communities with low species
diversity and simple trophic structures (Lenz, 1987; Lenz and Browne, 1991). Artemia can
be found in a great variety of habitats in terms of water chemistry (Lenz, 1987; Bowen et
al., 1988), altitude (Triantaphyllidis et al., 1998; Van Stappen, 2002) and climatic
conditions, from humid-subhumid to arid areas (Vanhaecke et al., 1987).
The first use of Artemia nauplii, hatched from cysts, is known from the 1930s when this
zooplankton organism was used as a suitable food source for fish larvae in the culture of
commercially important species (Sorgeloos, 1980b; Léger et al., 1986). Since then, Artemia
has been found to be a suitable food for diverse groups of organisms of the animal
kingdom, especially for a wide variety of marine and freshwater crustaceans and fishes
(Sorgeloos, 1980b). Also decapsulated Artemia cysts, juvenile and adult Artemia have
increasingly been used as appropriate diets for different fish and crustacean species
(Sorgeloos et al., 1998; Dhont and Sorgeloos, 2002; Lim et al., 2003).
Since the early 1990s cyst consumption has increased exponentially as a consequence of the
rapidly expanding shrimp and marine fish industries (Sorgeloos et al., 2001; Dhont and Van
Stappen, 2003). On the other hand, the limited supply of Artemia cysts, originating from
natural harvests, may lead to a serious bottleneck in many aquaculture developments
(Lavens and Sorgeloos, 2000b). In particular, in South East Asia where no natural
populations of Artemia occur, therefore diversification of Artemia sources has been
considered a possible solution to sustain the fast growing aquaculture industry. This
strategy has been performed by the exploration of natural harvesting from new Artemia
sites such as China (Xin et al., 1994), Iran (Van Stappen et al., 2001), Mexico and Chile
(Castro et al., 2006) etc. Furthermore, man-made introduction of Artemia into saltworks
and man-made ponds has also contributed to supplement cyst supply. This approach has
been conducted during the last couples of decades in several countries with a monsoon
climate. For instance, Philippines (De Los Santos et al., 1980), Thailand (Tarnchalanukit
and Wongrat, 1987), Vietnam (Quynh and Lam, 1987; Brands et al., 1995) and other
countries such as India, Sri Lanka, Iran (Hoa et al., 2007).

In Vietnam, Artemia production is successfully conducted on a seasonal basis in the
coastal areas of the Mekong Delta, southern Vietnam (Brands et al., 1995; Baert et al.,
1997). To date this region is an important supplier of high-quality Artemia cysts that are
used in domestic aquaculture as well as for export. This activity has had significant positive
socio-economic impacts for the local rural populations (Hoa et al., 2007; Son, 2008). In
practice, cysts produced during the previous culture season are used to establish, by
inoculation, a new population of Artemia. This practice may favour the accumulation of
adaptations to the new environment (Frankenberg et al., 2000). This Artemia culture system
is referred to as semi-intensive (Tackaert and Sorgeloos, 1991) and static (Quynh and Lam,
1987; Brands et al., 1995). Semi-intensive refers to small seasonal man-managed ponds in
which Artemia is inoculated at high densities (between 60 and 100 nauplii L-1). Ponds are
managed intensively (i.e. inoculation of selected strains, manipulation of primary and
secondary production, predator control, etc.) but most of the management procedures are
empirical. Furthermore, Artemia production in Vietnam has largely focused on cyst
production, and all techniques and methodologies developed to optimize Artemia
production have used maximal high-quality cyst production as their primary target (Brands
et al., 1995; Baert et al., 1997; Hoa et al., 2007).
Artemia is a non-selective particle feeder, feeding on microalgae, detritus and bacteria,
where the only limiting factor is the size of the ingested particles (Van Stappen, 1996;
Fernández, 2001; Dhont and Sorgeloos, 2002). Although the feeding and filtration biology
of Artemia has been studied in laboratory tests (Coutteau and Sorgeloos, 1989; Evjemo and
Olsen, 1999; Fernández, 2001), up to now, this type of study has not been extended to the
field, and there is very little information on optimal Artemia biomass production in salt
works. Artemia biomass is an excellent food source in aquaculture as it converts detritus
and phytoplankton into high-quality proteins, thus extracting nutrients from the aquatic
environment (Sorgeloos, 1985). Artemia biomass is valorised as a high-quality feed for
ornamental fish (Lim et al., 2001; 2003), as a nursery food for marine fish, shrimp, prawn
and crab (Merchie, 1996; Sorgeloos et al., 1998; Dhont and Sorgeloos, 2002), as an overall
high-protein ingredient for aquaculture feeds, and as maturation trigger in shrimp
broodstock (Naessens et al., 1997; Wouters et al., 2002).
In pond systems, the success of Artemia cyst and biomass production relies on the
favourable growth of the Artemia population after inoculation. This growth is, amongst
others, significantly influenced by the food management of the culture ponds. The final
yield of Artemia biomass can also be considerably affected by various technical aspects,
such as harvesting strategies (Brands et al., 1995; Baert et al., 1996, Anh and Hoa, 2004).
Hence, substantial research is required to (1) optimize culture techniques, in particular in
relation to the effects of organic and inorganic fertilizers on the production of microalgae as
a natural food for Artemia, (2) on the use of supplementary feeds and (3) on adequate
harvesting strategies. Moreover, there is a need for (4) research into the possible
applications of Artemia biomass products in Vietnamese aquaculture. Farming of highly
valuable aquaculture species in the Mekong delta has been studied for several species such
as Penaeid shrimp (Nghia et al., 1997a,b; Phuong et al., 2008), freshwater prawn
Macrobrachium rosenbergii (Thang, 1995; Lan et al., 2006). Similar work exists for the
mud crab Scylla spp. (Dat, 1999; Ut et al., 2007a,b) and for different types of polyculture of
marine and freshwater species (Rothuis et al., 1998; Minh et al., 2001; Lan et al., 2003).
Recently, Vietnamese aquaculture activities have been expanding with the culture of new
target marine aquatic species such as swimming crab (Portunidae), cobia (Rachycentridae),
grouper (Serranidae), goby (Gobiidae), eel (Anguillidae), Areola babylon (Buccinidae), etc.
(MoFI, 2006). These new species offer opportunities for diversification in the use of
Artemia, including live juveniles and adults as well as frozen or dried Artemia biomass.
This indicates that there is a high potential market for Artemia biomass not only in the
Mekong Delta but also along the coast line of central Vietnam (Hoa et al., 2007).