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Successful Production in Semi-biofloc in Indonesia
An Aquaculture Experience Farm in Java operates a hybrid system,
based on a careful balance between autotrophic and heterotrophic
organisms which gave average outputs of 20 tonnes/ha in early 2013, Agus
Saiful Huda, Junaedi Ispinanto, Fauzan Bahri and Olivier Decamp, INVE
Aquaculture report.
High water exchange is standard practice
to maintain suitable water quality in intensive shrimp production
systems. However, environmental and biosecurity issues led farmers to
develop methods relying on reduced or zero water exchange. A method that
is commonly found in Thailand relies on recirculation systems where
incoming water is treated in a reservoir before being pumped into
rearing ponds, and where the pond effluent is directed towards a
settling pond and treated before being either discharged to the
environment or re-used for the next pond stocking.
Another example is the Biofloc Technology (BFT) system that was
developed to reduce the risk of pathogen entry, minimise effluent
discharge and protect the surrounding environment. For further
information on BFT, please refer to publications in trade magazines and
scientific journals, including those of Dr Yoram Avnimelech and Dr Ngan
Taw.
The concept was applied in Indonesia, first at PT Central Pertiwi
Bahari, then at other farms in Medan, Java and Bali. The success of
these systems relies on high stocking density, adequate aeration, as
well as the right amount and form of carbon/nitrogen ratio fed to the
system. The understanding of the basic concept, the right tools to
monitor the system and the right infrastructure will explain the success
or failure of the technology under commercial conditions.
Despite the interest of many Indonesian shrimp farmers in the
technology, the failure of various projects due to unsuitable facilities
(no back-up in the case of power failure and limited monitoring), or
incorrect number and position of the paddlewheel aerators, led farmers
to move away from BFT. Many Indonesian farms (around 50%, personal
communication Cindomas) switched to the semi-biofloc system (i.e. the
hybrid system), using a rearing protocol adapted to local
characteristics, facilities and infrastructure. The purpose of this
article is to describe the semi-biofloc or hybrid system, as applied in
farms in East Java.
The hybrid system, as operated in many Indonesian farms, is based on a
careful balance between autotrophic and heterotrophic organisms. These
organisms create what we call bio-microfloc which is a smooth and
compact aggregate matter made of green algae (mostly chlorella) and
bacteria (mostly Bacillus supplied via commercial probiotic),
as well as detritus, organic particles and protozoa. The organisms from
the bio-microfloc control water quality by converting uneaten feed, dead
plankton and shrimp faeces into compounds that are non- toxic.
This action of the biofloc organisms not only detoxifies the system
but also improves the stability of the rearing environment. As a
consequence, the bio-microfloc can be called ‘bio-conditioner’. The
bio-microflocs are also a natural source of food for shrimp. For further
information on the composition of the biofloc, and also the impact of
probiotics on the nutritional value of the biofloc, we refer to
publications, among others, from The Oceanic Institute (USA), Texas
A&M (USA), Waddell Mariculture Center (USA), and the Fundação
Universidade Federal do Rio Grande (Brazil).
Contrary to the full BFT, the balance between phytoplankton and
bacteria is of the order of 30-40% autotrophs and 60-70% heterotrophs.
With the development of the bio-microfloc, the pond water colour can be
described as light brown or cream. The volume of bio-microfloc in the
pond water has to be managed through the addition of chemicals (calcium
carbonate, magnesium carbonate), organic matter, and microbial products
(Sanolife PRO-W) or limited water exchange.
The shrimp pond is prepared for 20 days and stabilised (with algae
and bacteria) before stocking the post larvae (PL10). Key parameters are
water colour, pH, alkalinity, and the composition of plankton and
bacteria. As with BFT, aeration is very important. Paddlewheels must be
positioned correctly in order to maximize oxygenation (above 4 ppm, for
shrimp and the organic degradation of organic matter), improve water
circulation and mixing (to avoid stratification) while directing the
sludge towards the central area of the pond. (Photo 1)
Photo 1. View of pond with paddlewheel aerators
Problems with aerators can affect the suspension of biofloc, thus
leading to the accumulation of biofloc biomass, the creation of anoxic
zones and the dramatic reduction in dissolved oxygen. Power failures
over an hour in duration can be critical. Back-up power generators must
be available. Contrary to the zero-water exchange heterotrophic system,
siphoning is routinely performed to control the organic matter
(especially excess nitrogen), as well as the checking for the presence
of dead shrimp. Water transparency is maintained at a Secchi disk
reading of 25-30 cm. Limited water exchange is carried out if required.
Example from a farm in Indonesia
The farm, Aquaculture Experience, is located in Kabupaten Lamongan,
East Java. It includes 40 ponds, of an average size of 3,000 m2 . Ponds are fully lined with HDPE. The total area of the farm is 27 ha.
Preparation for 20 days prior to stocking
After preparing the reservoir and pond, including setting up the
biosecurity measures, i.e. crab protection and bird nets, the important
phase of water preparation starts. This is the disinfection of the water
using Sanocare PUR 1.2 ppm, followed by the initial enrichment of the
rearing environment with the right nutrients. These include dolomite (10
ppm), a source of calcium carbonate and magnesium carbonate (Kaptan 3
ppm) and Bacillus mixture (Sanolife PRO-W 10 ppm). The small particles, together with the Bacillus
mixture, are in fact a ‘floc starter’. These products are applied on a
regular basis over a period of 2 weeks or so until the pond water is
stable with the right balance of microorganisms. This is followed by the
‘directing phase’ where a more stable environment is obtained (Figure
1).
Culture operations
After stocking animals (PL10), the pond management consists of
maintaining a stable environment through (1) strengthening the system
and (2) controlling the system. The composition of the algal community
is controlled through the manipulation of the N: P (nitrogen:
phosphorus) ratio following Redfield stoichiometry, with targets of N: P
ratio of 25: 1 (20-25 ppm nitrate and 0.5-1 ppm phosphate).
Frequent addition of a source of nitrate (Sanolife Nutrilake 5 ppm)
is required. In order to maintain the right equilibrium between algae
and bacteria, the right mixture of Bacillus is frequently
applied (Sanolife PRO-W 10 ppm). In order to compensate for mineral
deficiencies, additives are mixed with the feed (protein content of
30-35%). Molasses is added 2 or 3 times per week at a dose of 10-15
kg/ha.
A combination of Sanolife PRO-W, dolomite and Kaptan 5 ppm is applied
to establish and maintain aggregate (microfloc), with a target of 2-3
mL/L volume in Imhoff cones within 1.5-2 hours. This is different from
the BFT system where the biofloc volume is generally higher, up to 15
mL/L. In order to maintain the stability of the system, water exchange
is kept at a minimum. In addition to water quality management, feeding
and shrimp health management, the mixed biofloc system also requires
specific attention.and management.
This includes the use of a central drain and siphon to remove the
excess organic matter that would accumulate in the central area of the
pond (following the right positioning of the paddle wheel). An
additional benefit of the frequent siphoning is the evaluation of the
shrimp moult and the observation of dead shrimp that would have
accumulated in the central area (Photo 2).
Figure 1. Overview of the various phases in the hybrid system, as operated at the Aquaculture Experience farm.
Photo 2. After siphoning, workers check for dead shrimp or any indication of problems in the pond.
Two additional steps are taken. The immune system of the shrimp is
optimised through the regular coating with a mixture of immunostimulants
and nutraceuticals (Sano TOP-S). The feed conversion rate is improved
through the coating of probiotics (Sanolife PRO-2).
Performance of recent crops
Tables 1 and 2 give the results of the last two culture cycles in
late 2012 and early 2013 respectively. The operation at the farm with
the hybrid system has led to the stable production of shrimp. The
stocking density is only an estimation as there is a tendency for
hatcheries to supply a higher number of PLs to the farm. Fine-tuning of
the protocol to the conditions prevailing in this part of East Java led
to an improvement of the feed conversion ratio (FCR) with an increase in
the productivity.
Table 1. Harvest data from Aquaculture Experience farm operated under semi-biofloc in autumn 2012.
Table 2. Harvest data from Aquaculture Experience, farm operated under semi-biofloc in January 2013.
The phytoplankton was dominated by green algae with blue-green algae
kept below 10% of the total community most of the time. Water
transparency was reduced from 40-60 cm in the first weeks of the crop to
20-30 cm in the last 2 months of the crop (Figure 2).
Conclusions
As with other intensive shrimp rearing systems, it is important to
have a well defined check list for each stage of cultivation, detailing
the potential hazards at each stage, the precautionary measures, the
parameters to be followed, and also the contingency plan. For each
problem, an action plan (a solution) should be defined in advance.
Looking at the ‘Early Warning System’, based on daily observation, we
include parameters such as discolouration of the shrimp, changes in
body shape and behaviour, extreme size variation, status of shrimp
hepatopancreas and faeces, and slower growth rate.
Figure 2.
Characteristics of the phytoplankton: water transparency (Secchi disc
reading, cm), percentage of green algae and blue green algae in the
total phytoplankton.
The important points to consider are:
- Production must be biologically feasible, but also technically and economically viable.
- Production should be right from the first time. Avoid the mistake at the beginning.
- Prevention and control of disease through:
a. Reduction and control of stressful factors. System must be as stable as possible.
b. Stimulation and activation of the
immune system continuously. This is achieved through the coating of a
mixture of immunostimulants and nutraceuticals.
c. Control of pathogens, such as Vibrio, virus and fungi.
d. Identification of appropriate treatment in case of disease.
e. Containment of disease.
f. Optimization of the feed digestibility and absorption. This is achieved through the coating of Bacillus probiotics.
January 2016
Fonte: http://www.thefishsite.com/articles/2156/successful-production-in-semibiofloc-in-indonesia/
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