Study of Recirculation Semi Intensive Seed Production (RESISP) 1207
Study of Recirculation Semi Intensive
Seed Production (RESISP) 1207
Masatoshi FUTAGAWA / CORDUNAP
September 7, 2012
Based on SISP (semi intensive seed
production) operation on October 2010, the method had disadvantages of
difficulty of larva estimation. The method improved to RESISP that culture
water at copepoda tank recirculates to separated larva tank.
The trials are conducting from July 2012
and 2nd trial is running now. There are some observations found and
information below.
RESISP1207
1st trial was conducted 23
days from July 28 to August 13, 2012. The system consist copepod tank (20 m3),
two larva tanks (1 m3) and pump (0.85kw, 3.8A). Copepod tank equip
three air stones at 50 cm depth due to low air pressure, two airlifts (lift up
water from bottom) and submersible light (400W). Bottom water was supplied to Larva
tank1 and return to copepod tank. Surface water was supplied to Larva tank 2 and
drain to outside of the system. Submersible light enhance growth of
phytoplankton during cloudy and the night, operated 18:00 to 7:00.
Initial water was
introduced with 120 µm bag-net on July 21 and fill up to 20 m3 until
3rd days culture (DC). Filter water was supplied 3 to 5 % per day
basically and increased 20 to 24 % when pH rose to over 8.2. Fertilizer,
potassium nitrate (15-0-14, 3ppm) and triple superphosphate (0-14-0, 0.5 ppm),
were applied after soaking in water by blender every day until 18 DC. Water temperature
(WT) and pH were read every morning at 10 AM.
Average WT was
17.1±0.3 ºC and
pH was 8.0±0.2 during culture. Water color turned to green at 5 DC and turned
to brown after that. Skeletonema spp.
and Chaetoceros spp. were abundant and
pH rise to 8.6 on 11 DC. Recirculation system was not operated due to over
capacity of pump, the motor became hot because of too much closed outlet.
However, the
planktons corrupted due to strong sunlight on 19 DC and culture water turned to
transparent. There were very few plankton observed, dead ones accumulated on
bottom and rot, mold grew. The operation was terminated at 23 DC and drained
totally on August 23.
Observations
There are several observations that
improve phytoplankton and copepod production as below.
- Intensive cultured phytoplankton like T-Isochrysis inoculated during initial water supply and culture useful phytoplankton to produce copepod easily.
- Fertilizers apply until water has color, until 3 to 5 DC usually.
- Filter water until water color turn to brown and remove bag-net to introduce copepod with supply water. In addition to that, inoculate copepods that come from intensive culture was ideal.
- Feed artificial feeds powder (1g/m3/day) when supply water without bag-net to enhance copepod propagation.
- Capacity of pump related to copepod multiplication and larva growth that 10 to 20 % of copepod biomass per day, equivalent 20 to 30 % of copepod tank volume approximately.
- Centrifuge pump is not ideal to moving water that damage plankton and copepod. Ideally, the water carries by airlift but it can’t lift more than 3 cm. It needs to invent how to lift higher.
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