Tài liệu này là một nghiên cứu về chuyên đề mô hình aquponic. Aquaponic hiện là mô hình sản xuất đang được áp dụng nhiều tại các nước phát triển để tạo nguồn thực phẩm rau sạch, thủy sản sạch. Ngoài ra Mô hình auqaponic được áp dụng ở những khu vực đô thị, hay khan hiếm về nước. Tài liệu hoàn toàn bằng tiếng anh, nên đòi hỏi người đọc cần có khả năng tốt về ngoại ngữ này.
Trang 1Effects of feeding frequency and photoperiod on water quality and
Jung-Yuan Lianga, Yew-Hu Chiena,b,*
a Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan
b Center of Marine Biotechnology and Bioenvironment, National Taiwan Ocean University, Keelung, Taiwan
a r t i c l e i n f o
Article history:
Received 25 December 2012
Received in revised form
30 March 2013
Accepted 31 March 2013
Available online 2 May 2013
Keywords:
Fish waste water
Aquaponics
Photoperiod
Feeding frequency
Tilapia
Water spinach
a b s t r a c t
A factorial arrangement of 6 treatments, 2 photoperiods for water spinach Ipomoea aquatica (12-h or 24-h light per day) X 3 feeding frequencies for red tilapia Oreochromis sp (an equal daily ration evenly fed 6, 4 or 2 times at 4-h, 6-h or 12-h interval, respectively) were assigned to 12 tanks Each tank was an aquaponics system containingfish and raft-supporting plant Water loss in 4 weeks was 3.3%, due to leaf transpiration mainly and evaporation Water quality remained safe and stable Nofish died Overall average weight gain was 43.9% for fish and 169.0% for plant 24-h light resulted in 2.4% higher fish growth, 12% higher plant growth and lower accumulation of all nitrogen and phosphate species in water than 12-h light Increased feeding frequency favored stable and good water quality and fastenedfish growth and plant growth by as much as 4.9% and 11%, respectively
Ó 2013 Elsevier Ltd All rights reserved
1 Introduction
Aquaculture is the culture of aquatic organisms, commonly
referred as animals, in a designated water body The water needs to
be treated whenever toxicants in it have built up beyond animal’s
safe level Toxicants such as ammonia and nitrite are derived from
decomposition of unconsumed feed and metabolites or waste of
the animals Hydroponics is the culture of aquatic plants in soilless
water where nutrients for plant’s growth come entirely from a
formulated fertilizer Aquaponics (a portmanteau of the terms
aquaculture and hydroponics) integrates aquaculture and
hydro-ponics into a common closed-loop eco-culture where a symbiotic
relationship is created in which water and nutrients are
recircu-lated and reused, concomitantly fully utilized and conserved In
aquaponics system, waste organic matters from aquaculture
sys-tem, which can become toxic to animals, are converted by microbes
into soluble nutrients for the plants and simultaneously,
hydro-ponics system has already treated the water and recirculates back
to aquaculture system with cleansed and safe water for the animals
Besides its ecological merits, aquaponics system can obtain extra
economic advantages: saving cost (input) on water treatment for aquaculture system, saving another cost on formulated fertilizer for hydroponics system and benefit from double outputs, harvest of animal and plant, by a single input,fish feed
Tilapia is the most commonly usedfish in aquaponics systems (Rakocy et al., 2006) for their high availability, fast growing, stress and diseases resistant and easy adaptation to indoor environment (Hussain, 2004) Water spinach or swamp cabbage Ipomoea aquatica
is a semiaquatic tropical macrophyte and commonly grown as a leaf vegetable in East and Southeast Asia It has hollow stems, rooting at the nodes and flourishes naturally in waterways or moist soil It requires little care to grow and hence low cost and popular in Taiwan It has been found effective in treating aquaculture waste water (Li and Li, 2009) and eutrophic water with undesirable levels
of nitrogen and/or phosphorus (Hu et al., 2008) Nutrients dynamics are quite complex in aquaponics system (Seawright et al., 1998) In such system, feed is the primary source of nutrients which are eventually tied up as the biomass of animal, plant and microbes or stayed free in water When no discharge, no nutrients are output until the animal and plant are harvested as economic crops Through microbial decomposition, the insoluble fish metabolite and un-consumed feed are converted into soluble nutrients which then can
be absorbed by plant Therefore, plant growth and production are indirectly related to feeding strategies,fish metabolic condition and microbial activity While plant removes the soluble nutrients, water
* Corresponding author Department of Aquaculture, National Taiwan Ocean
University, Keelung, Taiwan Tel.: þ886 2 24622192x5204; fax: þ886 2 24625393.
E-mail address: yhchien@mail.ntou.edu.tw (Y.-H Chien).
Contents lists available atSciVerse ScienceDirect
International Biodeterioration & Biodegradation
j o u r n a l h o m e p a g e : w w w e l s e v i e r c o m / l o c a t e / i b i o d
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International Biodeterioration & Biodegradation 85 (2013) 693e700
Trang 2isfiltered Consequently, water quality or safe guard of fish growth
and production depends highly on the disposal capacity of the plant
Besides the above factors which affect the nutrient availability
for plant andfish, system designs, plant and fish species and other
physical factors such as temperature, light sources and photoperiod
all add up the managing complexity for a steady state of nutrient
flow, which can be essential for the stable and predictable
pro-duction offish and plant in aquaponics system Since photoperiod
affects photosynthesis and plant growth, the increase of
photope-riod may also increase the removal capacity of nutrients in aquatic
macrophyte Some studies have showed that the growth and
pro-ductivity offloating aquatic macrophytes are directly related to the
intensity and amount of light, so are the absorption rates for
nu-trients (Gopal, 1987;Urbanc-Bercic and Gaberscik, 1989).Petrucio
enabled two aquatic macrophytes to reduce more nutrients from
the water Feeding frequency can affect feed intake offish, quantity
of uneaten feed, feed utilization efficiency and consequently,
metabolite and excreta offish and water quality In an intensive
culture of fingerling walleye Stizostedion vitreum, Phillips et al
daily dissolved oxygen (DO) and lower total ammonia nitrogen
Postlarval Ayu Plecoglossus altivelis with higher feeding frequency
at lower feeding rate had higher survival and growth (Cho et al.,
2003) When fed at 10% body weight daily, newly weaned
Austra-lian snapper Pagrus auratus fed 8 times a day had higher growth
and lower size heterogeneity than fed 4 and 2 times a day (Tucker
et al., 2006) Therefore, in the present study we investigate under a
constant nutrient input, namely, the feeding rate, if increasing
photoperiod can increase plant production, concomitantly, plant’s
filtering capacity and nutrient concentration in water and also if
increasing feeding frequency can even out through time, fish
metabolite and excrete, concomitantly, stabilize water quality and
increasefish production
2 Materials and methods
The experiment had a factorial arrangement of 6 treatments,
namely, 3 feeding frequencies for red tilapia Oreochromis sp X 2
photoperiods for water spinach I aquatica Forsk Illumination was
12 h or 24 h daily An equal daily ration was evenly fed to thefish 2,
4 or 6 times at 12-h, 6-h and 4-h interval, respectively Each
treatment had 2 replicates or experimental units The experiment
was completed in 4 weeks
Each experiment unit had an orange plastic tank (115 cm L
102 cm W 99 cm H), filled with 1000 L freshwater and stocked
with 8fish at 467 30 g each or around 3.7 kg m3 Constant
aeration was provided at tank bottom by a membrane disc diffuser
(LTD-325/325 mm, Aquatek, Kaohsiung, Taiwan), which had a
membrane diameter of 32.5 cm and provided an intensive air
throughput of 0.02e0.12 CMM 1e3 mm diameter air bobbles A
piece of 3-cm thick polyethylene raft covered almost entire water
surface except a 15 cm 15 cm corner cut open, allowing an
automatic feeder release pellet feed into the water A cut plant stem
25.1 3.7 cm or 7.8 0.5 g was wrapped around with layers of
sponge, stuffed in a black plastic ring (4.5-cm D) thenfit into one of
the 63 evenly distributed round holes Total plant biomass on a raft
was 490.2 5.5 g Part of a stem was submerged to expose its first
bottom node, allowing for root initiation A piece of coarse screen
(2.54 cm mesh) was secured 20 cm below the polyethylene raft to
prevent the plant root from possible disturbance by thefish Each
tank was encased in a 200-cm tall wooden framework, which a
timer, a feeder and an illumination device could befixed onto A
near-sunlight 28-W 115-cm T5 tube was used for illumination,
hanging 25 cm above plant top and its height was adjusted as the
plant grew Top and sides of the framework were covered with black vinyl to obstruct the interference of illumination from outside
Each day same ration of feed for all experimental units was hand loaded in the funnel of a feeder Coupled with a timer, the feeder released feed 2, 4 or 6 times a day at 12 h, 6 h or 4 h interval, respectively, as designated in the experimental design In this 4 week period, daily ration was gradually decreased from 5% to 3% fish biomass as fish grew A commercial tilapia feed was used, which contained 25% crude protein, 3% crude fat, 12% crude ash, 6.5% crudefiber, 2% acid insoluble and 11% moisture No water was added or exchanged throughout the experiment
Water was sampled weekly and monitored for pH (HM-20P, DKK-TOA, Tokyo), dissolved DO and temperature (Oxi 330i, WTW GmbH, Weilheim, Germany) and electrical current (EC) (750II conductivity/TDS monitor, Myron L Company, Carlsbad, CA) Total ammonia-N (TAN), nitrite-N, nitrate-N, total nitrogen, soluble phosphate-P, total phosphorus were analyzed by flow injection analyzer (FIA) (Flow SolutionÔ FS3100, O I Analytical, College Station, TX) The absorbance wavelengths used and methods based for the analysis of those substances were 640 nm and phenol hy-pochlorite method (Solorzano, 1969) for ammonia nitrogen,
543 nm and Pink azo dye method (APHA, 1992) for nitrite nitrogen,
543 nm and CdeCu reduction method (Bendschneider and
ni-trate nitrogen, 543 nm and CdeCu reduction method (Strickland
nitrogen, 885 nm and molybdenum blue method (Strickland and Parsons, 1972) for phosphate and 885 nm and method by
phosphorus Analysis of five days’ Biochemical Oxygen Demand (BOD5) was based bySawyer et al (2003) Biomass offish and plant was measured at 0, 2 and 4 wk In wk 2, plant 25 cm above the raft was cut, weighed and harvested In wk 4, allfish and whole plant were harvested Fish weight gain (%) was calculated as the ratio of average individualfish weight in wk 2 or wk 4 to average individual fish weight in wk 0 Plant weight gain (%) in wk 2 was calculated as the ratio of the biomass of cut part/initial biomass and plant weight gain (%) in wk 4 further added the ratio of the biomass of whole plant/initial biomass
Three-way ANOVAs were performed to determine time effect, the effects of photoperiod and feeding frequency and their inter-action onfish and plant growth and water parameters Duncan’s multiple range test (DMRT) was used to compare differences among levels of a factor The significant level applied to all analyses was set to 5% SAS version 9.0 software (SAS Institute, Inc., Cary, NC) was used for statistical analysis
3 Results and discussion 3.1 System setup (Fig 1) Raft aquaponics can be the most simple and least cost aqua-ponics system The essential elements of an aquaponic system as suggested byRakocy et al (2006)arefish-rearing tanks, a settleable and suspended solids removal component, a biofilter, a hydroponic component and a sump In raft aquaponics if the plant and its supporting media such as gravel and coarse sand can provide suf-ficient biofiltration, a separate biofilter is not needed (Rakocy et al., 2006) Solids removal component is highly recommended by
fish fecal waste and unconsumed feed accumulate, deposit and decompose anaerobically in tank bottom, the reduced toxic prod-ucts can deteriorate water and harm thefish In our system, the upwelling afloat from disk membrane diffuser kept the solids J.-Y Liang, Y.-H Chien / International Biodeterioration & Biodegradation 85 (2013) 693e700
694
Trang 3suspended and the effective aeration from the diffuser could
mineralize the organic particles so that little deposition was
observed in tank bottom at the end of experiment
The level of polyethylene raft descended average 3.3 cm so that
the water loss in 4 wk was estimated only about 3.3% or about
0.1% d1 Since water surface was afloat with polyethylene raft, only
the feeding corner area (15 cm 15 cm) was open to evaporation
Other part of the water loss could be attributed to transpiration at
the leaf surface, which could be quite limited, too Aquaponic
sys-tem is a recirculating aquaculture syssys-tem (RAS) as defined by
Blidariu and Grozea (2011): an aquaculture system that in-corporates the treatment and reuse of water with less than 10% of total water volume replaced per day Water replacement can vary with the system setup In a Nile tilapia and lettuce aquaponics system wherefish culture tanks, aquaponic channels, netting tanks, clarifier and sump were open to evaporation, 1.4% of the total sys-tem water was added daily to compensate the evaporation and transpiration losses (Al-Hafedh et al., 2008) The water consump-tion forfish production in the present study was 0.020 m3kg1or 20.0 L kg1when calculating from the following data on per tank base: initialfish biomass 3.7 kg, overall average fish weight gain 43.9%, initial water volume 1000 L, water loss 3.3% The other water consumption data from previous studies are as the following: extensivefish culture >5 m3kg1and semi-intensivefish culture 2.5 m3kg1(both cited byAl-Hafedh et al., 2008), aquaponics by
(1997)0.25 m3kg1 3.2 Treatment effects onfish survival and growth and plant growth (Fig 2)
Both feeding frequency (FF) (no of meals d1) and photoperiod (PP) (illumination h d1) had no effect onfish mortality since no fish died throughout the experiment Increased FF favored fish growth since in wk 2fish weight gain (WG) for 6 d1was already 1.2% and 2.2% higher than WG for 4 d1and 2 d1, respectively, but there was no difference between WG for 4 d1and for 2 d1 FF effect on growth became even more pronounce in wk 4 that 6 d1 had 3.0% and 4.9% more WG than 4 d1 and 2 d1, respectively Generally,fish growth increases with feeding frequency In indoor, intensivefish culture systems, fish may be fed as many as 5 times per day in order to maximize growth at optimum temperatures
Feeding frequency
b 20.0 (0.9)
b 41.6 (1.9)
b 21.0 (0.9)
b 43.5 (1.9)
a 22.2 (0.4)
a 46.5 (0.8)
10
20
30
40
50
60
c 133 (4)
c 164 (8)
b 134 (4)
b 169 (9)
a 138 (6)
a 175 (8)
120
140
160
180
200
Photoperiod 12h d-1 24h d-1
b 20.5 (1.7)
b 42.7 (3.5)
a 21.6 (1.1)
a 45.1 (2.3)
10
20
30
40
50
60
b 131 (2)
b 163 (6) a
139 (3)
a 175 (4)
Fig 2 Mean value and standard deviation (in parenthesis) of fish weight gain (upper) and plant weight gain (bottom) of the tilapiaewater spinach aquaponic system under the effects of feeding frequency (n ¼ 4) (left) and photoperiod (n ¼ 6) (right) during two sampling periods Mean values without sharing a common letter are significant different
0.05).
Fig 1 A tilapiaewater spinach raft aquaponics system setup.
Trang 4Feeding frequency
a
6.5
(0.1)
a 25.4 (1.0)
a 38.8 (1.3)
a 44.7 (5.8)
a 46.0 (4.6)
a
6.5
(0.1)
a 23.8 (0.9)
b 35.7 (2.8)
b 38.6 (10.0)
b 40.9 (7.8)
a 6.5 (0.1)
a 24.1
ab 36.6 (5.1)
b 37.3 (13.6)
c 37.4 (9.9)
-1 )
a
0.1
(0.1)
a 21.5
a 33.0 (3.2)
a 36.7 (3.6)
a 38.5
a 0.1
(0.1
a 21.3
a 32.4
ab
(6.1)
a 0.1 (0.1)
a 20.6
a 32.6
b 32.0
b 32.0
-1 )
Week
Photoperiod 12h d-1 24h d-1
a 6.5 (0.1)
a 25.4 (2.5)
a 38.9 (1.9)
a 46.3 (3.2)
a 47.8 (1.7)
a 6.5 (0.1)
a 23.4 (0.7)
b 35.1 (3.6)
b 34.1 (5.3)
b 35.1 (6.2)
a 0.1 (0)
a 20.5
a 33.6
a 40.0
a 39.9
a 0.1 (0.1)
a 20.9
a
30.1
0
10
20
30
40
50
-1 )
Week
Fig 3 Mean value and standard deviation (in parenthesis) of total nitrogen (upper) and nitrate-N (bottom) concentration in water of the tilapiaewater spinach aquaponic system under the effects of feeding frequency (n ¼ 4) (left) and photoperiod (n ¼ 6) (right) during two sampling periods Mean values without sharing a common letter are significant different (p 0.05).
Feeding frequency
a
0.1
(0)
a 0.8 (0.5)
a 3.2 (2.2)
a 4.7 (2.2)
a 5.0 (1.8)
a
0.1
(0)
a 0.7 (0.2)
a 1.1 (0.6)
ab 3.1 (3.1)
ab 3.0 (2.8)
a 0.1
(0)
a 0.8 (0.3)
a 0.7 (0.4)
b 2.0 (2.4)
b 2.2 (1.4)
0
1
2
3
4
5
6
7
8
-1 )
a
0.1
(0)
a 0.5 (0.2)
a 0.8 (0.2)
a 1.3 (0.4)
a 0.5 (0.7) a
0.1
(0
a 0.6 (0.2)
a 0.6 (0.2)
a 0.8 (0.7)
a 0.8 (0.6)
a 0.1 (0)
a 0.6
(0.1)
a 0.7
0.5 (0.2)
-1 )
Week
Photoperiod 12h d-1 24h d-1
a 0.1 (0)
a 0.9 (0.2)
a 1.8 (1.6)
a 6.2 (0.7) a
5.2 (1.7)
a 0.1 (0)
a 0.6 (0.1)
a 1.5 (1.9)
b 1.3 (1.2)
b 1.6 (1.8)
0 1 2 3 4 5 6 7 8
-1 )
a 0.1 (0)
a 0.6 (0.1)
a 0.6 (0.2)
a 0.9
0.7 (0.2)
a 0.1 (0)
a 0.6 (0.1)
a 0.6 (0.2)
a 1.0 (0.2)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
-1 )
Week
Fig 4 Mean value and standard deviation (in parenthesis) of ammonia-N (upper) and nitrite-N (bottom) concentration in water of the tilapiaewater spinach aquaponic system under the effects of feeding frequency (n ¼ 4) (left) and photoperiod (n ¼ 6) (right) during two sampling periods Mean values without sharing a common letter are significant
0.05).
J.-Y Liang, Y.-H Chien / International Biodeterioration & Biodegradation 85 (2013) 693e700 696
Trang 5(Craig and Helfrich, 2002).Riche et al (2004)found that feeding
tilapia at intervals shorter than the time required for the return of
appetite can lead to gastric overload resulting in reduced
absorp-tion efficiency The return of appetite following a satiation meal,
defined as the point that consumption is equivalent to the amount
of the previous meal evacuated, is approximately 4 h in Nile tilapia
held at 28C In the present study, the interval of the highest FF,
6 d1was no shorter than 4 h and the absorption efficiency should
not be reduced In an intensive culture of fingerling walleye
S vitreum,Phillips et al (1998)found that higher frequency feeding
resulted in higher daily DO and lower TAN but had no effect onfish
growth and size distribution In conclusion, higher FF with less feed
given at a time can result in higher absorption efficiency and lower
excretion into water, consequently, less nutrient accumulation in
water
Long PP increased fish growth since full day illumination
(24 h d1) resulted in 1.1% and 2.4% higher WG than half-day
illu-mination (12 h d1) in wk 2 and wk 4, respectively The present
results was not consistent with the results of El-Sayed and
niloticus under four photoperiod (light:dark, L:D) cycles (24L:0D,
18L:6D, 12L:12D and 6L:18D) at same feeding rate and feeding
frequency for 90 days and found thatfish performance was not
significantly affected by photoperiods Since in all tanks the
poly-ethylene raft blocked most illumination onto the water, the only
difference in illumination resulted from the two PP was that the
feeding corner of 24 h d1received twice illumination as 12 h d1,
which might somewhat helpfish’s feeding and then the growth FF
and PP had no interaction effect onfish growth
Plant partial harvest in wk 2 had already showed thatfish FF
helped for plant growth since plant WG increased with FF, namely,
6 d1> 4 d1> 2 d1in both wk 2 and wk 4 In wk 4 while the whole plant was harvest, 6 d1had 11% and 6% more WG than 2 d1 and 4 d1, respectively Long illumination had positive effect on plant growth since PP at 24 h d1obtained 8% and 12% higher WG than 12 h d1in wk 2 and wk 4, respectively It is comprehensible that longer illumination resulted in longer photosynthesis and faster plant growth but not comprehensible how higher FF can link
to better plant growth
3.3 Treatment effects on nitrogen species (Figs 3and4)
In total nitrogen (TN), nitrate-N contributed around 88%, ammonia-N (TAN) 11% and nitrite-N < 1% Regardless of the treatments, the overall average TN, nitrate-N and TAN increased markedly until wk 2, slightly wk 2 to 3 and leveled off wk 3 to 4, showing their accumulation had lessened The overall average nitrite-N reached its peak in wk 3, 0.9 mg L1and decreased to 0.6 mg L1in wk 4 The ammonia (NH3) safe level for Nile tilapia is 0.42 mg L1(Stickney, 1979;Karasu Benli and Koksal, 2005) Since this safe ammonia level is expressed in terms of free NH3, it has to
be transformed into TAN When the NH3 fraction from TAN at overall average pH 6.69 and temperature 29.6 C, 0.5% are accounted for, the TAN safe level for Nile tilapia is 84 mg L1, which
is far higher than the highest TAN in the present study Therefore, it can be concluded that our aquaponics system ammonia toxicity risk free In the present study, the highly oxidized environment made nitrite-N, the transitional nitrogen species in nitrification process unstable and in very low concentration, and probably insensitive to the treatment effect throughout the experiment
TN, nitrate-N and TAN decreased with increased FF since wk 2
or wk 3 The adverse effect of FF on nitrogen species was most
Feeding frequency
a
3.6
(0.1)
a 15.6 (4.9)
a 36.4 (8.7)
a 61.8 (10.6)
a 70.7
a
3.3
(0.1)
a 12.6 (3.5)
b 22.0 (1.2)
a 53.6
a 71.6 (4.8)
a 3.6
(0.1)
a 14.8
b 25.4
a 57.1 (4.4)
a 63.6 (11.0)
-1 )
a
3.4
(0.1)
a 13.3 (3.8)
a 22.4 (4.2)
a 45.7 (7.6)
a 64.9 (6.6)
a
3.3
(0.1)
a 11.3 (1.1)
a 18.2 (3.2)
a 42.3 (4.2)
ab 62.5 (3.4)
a 3.4 (0.1)
a 12.6 (0.7)
a 20.4 (1.2)
a 40.7 (8.7)
b 56.7 (9.4)
-1 )
Week
Photoperiod 12h d-1 24h d-1
a 3.5 (0.1)
a 15.5 (3.1)
a 31.2 (9.8)
a 59.7 (7.7)
a 73.2 (5.3)
a 3.6 (0.1)
a 13.1 (2.7)
b 24.6 (5.8)
a 55.3 (6.5)
b 64.1 (8.4)
-1 )
a 3.3 (0.1)
a 12.8 (3.4)
a 21.3 (3.9)
a 47.7 (5.5)
a 65.7 (4.8)
a 3.4 (0.1)
a 12.0 (2.6)
a 19.4 (2.5)
b 38.1 (4.0)
b 57.1 (6.8)
-1 )
Week
Fig 5 Mean value and standard deviation (in parenthesis) of total phosphorus (upper) and phosphate (bottom) concentration in water of the tilapiaewater spinach aquaponic system under the effects of feeding frequency (n ¼ 4) (left) and photoperiod (n ¼ 6) (right) during two sampling periods Mean values without sharing a common letter are significant different (p 0.05).
Trang 6pronounced on TN and TAN in wk 4 when their concentrations
were in the order of 2 d1> 4 d1> 6 d1 FF showed no effect on
nitrite-N, possibly due to its low concentration, <1 mg L1, and
relatively wide variation Juvenile (3.0 0.2 g) gibel carp (Carassius
auratus gibelio) were fed to satiation for 8 weeks to investigate the
effect of feeding frequency (2, 3, 4, 12 and 24 meals per day) on
growth, feed utilization and size variation, the results showed that
apparent digestibility of protein and energy increased significantly
at high feeding frequencies (Zhou et al., 2003) Higher feeding
frequency leads to better apparent digestibility may explain lower
concentration of nitrogen excreted into water
PP exhibited its effect on reducing TN, nitrate-N and TAN since
wk 2, wk 3 and wk 3, respectively In wk 4, the reductions were
28.7% ((47.8 35.1)/47.8), 26.3% and 69.2% for TN, nitrate-N and
TAN, respectively However, PP had no effect on nitrite-N Various
nitrogen forms have different effects on growth and nitrogen
up-take of plants Several studies have shown that aquatic
macro-phytes grow well when NH4þis the main nitrogen source probably
because less energy is needed for NH4þ uptake and assimilation
compared to NO3 nutrition (Petrucio and Esteves, 2000;
Jampeetong and Brix, 2009) When four aquatic macrophytes were
supplied with different inorganic nitrogen treatments: NH4þ and
NO3 each alone and together, the NH4þ uptake rate was still
significantly higher than the NO3 uptake rate (Jampeetong et al.,
Eich-hornia crassipes under 12 h d1PP removed from water 7.4% more
TN and 4.1% more NH4þthan under 10 h d1PP
3.4 Treatment effects on phosphate species (Fig 5)
Both total phosphorus (TP) and phosphate ðPO4 Þ increased
continuously The overall average TP and PO4 were 27.9 mg L1
and 20.4 mg L1 in wk 2 and increased 146% and 201% to 68.7 mg L1and 61.4 mg L1in wk 4, respectively FF had no effect
on TP throughout the experiment FF was effective in reducing
PO4 until wk 4 when 6 d1had lower phosphate concentration than 2 d1 PP at 24 h d1resulted in lower TP than at 12 h d1in wk
2 and wk 4 and such lowering PO4 effect occurred in wk 3 and wk
under 12 h d1PP removes 9.2% more TP and 9.9% more PO4 than under 10 h d1PP
3.5 Treatment effects on electric current and BOD5(Fig 6) Dissolved nutrients are measured collectively as total dissolved solids (TDS), expressed as ppm, or as the capacity of the nutrient solution to conduct an electrical current (EC), expressed as millimhos cm1(mmho cm1) In the present study EC increased all the time Its overall average value was 376mmho cm1in wk 0 and increase 84% to 694mmho cm1in wk 4 This increase trend could
be attributed to the increase of ions derived from mineralization of accumulated organic matter Increased FF reduced EC starting in wk
3 In both wk 3 and 4, ECs in 6 d1and 4 d1were lower than EC in
2 d1but were not different between them PP also took effect in
wk 3 that 24 h d1had lower EC than 12 h d1 In wk 4, 24 h d1 reduced EC by 19% Rakocy et al (2006) considered that in an aquaponic system, TDS remains 200e400 ppm or EC 0.3e 0.6 mmho cm1will produce good results in plant production If dissolved nutrients are steadily increasing and approach 2000 ppm
as TDS or 3.5 mmho cm1 as EC, phytotoxicity can occur and increasing the water exchange rate or reducing thefish stocking rate and feed input will quickly reduce nutrient accumulation In the present study, the EC in wk 4 was around 700mmho cm1, of which the level of dissolved nutrients was suitable for plant’s Feeding frequency
a
376
(1)
a 429 (10)
a 510
a 649 (43)
a 746 (70)
a
376
(2)
a 403 (29)
a 467 (39)
b 582 (53)
b 663 (99)
a 376 (1)
a 410
a 475 (17)
b 554 (100)
b 655 (108)
a
5.5
(0.1)
a 26.3 (10.5)
a 49.9 (18.6)
a 69.8 (24.6)
a 80.3 (15.0)
a
5.6
(0.1)
a 18.4 (7.4)
a 28.9 (13.3)
a 78.8 (23.8)
ab 78.2 (24.8)
a 5.5 (0.1)
a 20.1 (10.5)
a 33.8 (15.6)
a 62.2 (20.0)
b 60.5 (28.5)
D 5
-1 )
Week
Photoperiod 12h d-1 24h d-1
a 375 (1)
a 422 (25)
a 500 (27)
a 649 (34)
a 762 (34)
a 376 (1)
a 406 (20)
a 468 (33)
b 541 (65)
b 614 (75)
a 5.5 (0.1)
a 24.5 (11.2)
a 43.2 (21.3)
a 80.6 (19.3)
a 88.3 (17.9)
a 5.5 (0.1)
a 18.7 (6.3)
a 31.9 (11.1)
a 59.8 (20.5)
b 57.7 (17.2)
D 5
-1 )
Week
Fig 6 Mean value and standard deviation (in parenthesis) of electrical conductivity (upper) and BOD concentration (bottom) in water of the tilapiaewater spinach aquaponic system under the effects of feeding frequency (n ¼ 4) (left) and photoperiod (n ¼ 6) (right) during two sampling periods Mean values without sharing a common letter are significant different (p 0.05).
J.-Y Liang, Y.-H Chien / International Biodeterioration & Biodegradation 85 (2013) 693e700 698
Trang 7growth and only 1/5 of the concerned EC, 3.5 mmho cm1, showing
that our aquaponics operated considerably satisfactory
The increasing trend of BOD5 lessened in wk 3 when overall
average BOD5in wk 3, 70.2 mg L1was not different from that in wk
4, 73.0 mg L1 Only until wk 4 when FF had effect on BOD5that
6 d1had 24% lower BOD5than 2 d1 Also only until wk 4 PP had
effect on BOD5that 24 h d1resulted in 35% less BOD5than 12 h d1
Among several conditions that biofilter performs optimally the
BOD5should be<20 mg L1(Rakocy et al., 2006) In the present
study the raft aquaponics system did not equip with a separate or
independent biofilter, but had water spinach’s root cluster and
polyethylene raft’s undersurface functioned as a biofilter, of which
the BOD5might not be subjected to the limitation of<20 mg L1
since BOD5in all treatments were already close to 20 mg L1in wk 2
and much greater afterward Lessfish excretion in higher FF can
be the reason for lower BOD5 PP at 24 h d1 might lead to
higherfiltering function in plant root and resulted in lower BOD5
than PP at 12 h d1 However, why until wk 4 this happened was not
known
3.6 Treatment effects on dissolved oxygen, pH and temperature
The overall average water temperature was 29.6 0.1C There
was no trend on temperature change with a maximum 30.1C in
wk 2 and minimum 29.4C in wk 4 FF did not affect temperature as
expected Full day illumination neither result in higher temperature
than half day illumination the possible reasons could be: (1) the T5
tube’s fluoresce light does not generate much heat and the tube
itself seldom reaches 37C as the specification claims, therefore,
not much difference in heat gain from longer illumination and (2)
polyethylene raft blocked the water from receiving light and itself
was a thermo insulator
The overall average pH was 6.7 0.3 Weekly average pHs were
7.2, 7.3, 6.4, 6.4 and 6.2 for wk 0 to 4, respectively A significant pH
drop during wk 1 to wk 2 could be coincided with the
measure-ment right after the plant’s partial harvest Speculation for such pH
change is not intended here since similar gap has not been
observed or evident in the other water parameters No treatment
effects, neither FF nor PP, were found
The overall average dissolved oxygen (DO) was 6.64
0.25 mg L1, which was 86e88% saturated since 100% saturation
level at water temperature 29e30C was 7.67e7.54 mg L1 It is
suggested that DO should be maintained>5 mg L1for aquaculture
(Boyd, 1992;Graber and Junge, 2009) Aeration provided all DO in
this system and the membrane disc diffuser had demonstrated its
efficiency here No time and treatment effects on DO were found
levels in aquaponics systems for the health of root (Goto et al., 1996)
and the elimination of reduced toxicants in water
4 Conclusion and recommendation
The present study demonstrated that the tilapiaewater spinach
raft aquaponics we used in this study was extremely effective in
fish waste treatment and also water conserved In 4 weeks’
pro-duction period, only 3.3% water was lost due to vegetable leaf
transpiration and minor evaporation Consequently, water
con-sumption forfish production was exceptionally low, 20.0 L kg1 No
fish died Overall average weight gain was 43.9% for fish and 169.0%
for plant Water quality remained safe and stable Furthermore, as
expected the extending photoperiod and increasing feeding
fre-quency increased bothfish and plant production and lessened the
accumulation of nitrogen and phosphorus nutrients in water These
findings are valuable and applicable in the development of
aqua-ponics and biological waste reuse
Current work can befine-tuned to increase feeding frequency to
8 d1and 12 d1and add two more illumination levels between
24 h d1and 12 h d1, namely, 20 h d1and 16 h d1so that a model for optimal feeding frequency and photoperiod can be constructed
to further improve the efficiency Researches are worth to explore
on the effects of various Illumination regimes, such as light in-tensity and light sources, i.e., different color LED (light-emitting diodes), T5, incandescent lamp, halogen lamp,fluorescence lamp and so on for most efficient illumination in energy saving, plant growth, water treatment andfish growth
References APHA (American Public Health Association), 1992 Standard Methods for Exami-nation of Water and Wastewater, eighteenth ed American Public Health As-sociation, American Water Works Association and Water Pollution Control Federation, Washington, D.C., USA.
Al-Hafedh, Y.S., Alam, A., Beltagi, M.S., 2008 Food production and water conser-vation in a recirculating aquaponic system in Saudi Arabia at different ratios of fish feed to plants Journal of World Aquaculture Society 39, 510e520 Blidariu, F., Grozea, A., 2011 Increasing the economical efficiency and sustainability
of indoor fish farming by means of aquaponics e review Animal Science and Biotechnology 44, 1e8.
Bendschneider, K., Robinson, R.J., 1952 A new spectrophotometric determination of nitrite in seawater Journal of Marine Research 2, 87e96.
Boyd,, C.E., 1992 Water Quality in Ponds for Aquaculture Alabama Agricultural Experimental Station, Auburn University, Auburn, Ms.
Cho, S.H., Lim, Y.S., Lee, J.H., Lee, J.K., Park, S., Lee, S.M., 2003 Effects of feeding rate and feeding frequency on survival, growth, and body composition of Ayu post-larvae Plecoglossus altivelis Journal of World Aquaculture Society 34, 85e91.
Craig, S., Helfrich, L.A., 2002 Understanding Fish Nutrition, Feeds, and Feeding Virginia Cooperative Extension Publication 420-256 Virginia Polytechnic Institute and State University, Petersbury, VA, p 5.
El-Sayed, A.M.E., Kawanna, M., 2004 Effects of photoperiod on the performance of farmed Nile tilapia Oreochromis niloticus: I Growth, feed utilization efficiency and survival of fry and fingerlings Aquaculture 231, 393e402.
Gopal, B., 1987 Water hyacinth Elsevier Aquatic Plant Studies 1, 471.
Goto, E., Both, A.J., Albright, L.D., Langhans, R.W., Leed, A.R., 1996 Effect of dissolved oxygen concentration on lettuce growth in floating hydroponicsProceedings of the International Symposium in Plant Production in Closed Systems Acta Horticulture 440, 205e210.
Graber, A., Junge, R., 2009 Aquaponic systems: nutrient recycling from fish wastewater by vegetable production Desalination 246, 147e156.
Grasshoff, K., Ehrhardt, M., Ehrhardt, K., 1983 Methods of Seawater Analysis Verlag Chemie, Federal Republic of Germany, p 419.
Hussain, M.G., 2004 Farming of Tilapia e Breeding Plans, Mass Seed Production and Aquaculture Techniques Bangladesh Fisheries Research Institute, Mymensingh
2201, Bangladesh, p 149.
Hu, M.H., Ao, Y.S., Yang, X.E., Li, T.Q., 2008 Treating eutrophic water for nutrient reduction using an aquatic macrophyte (Ipomoea aquatica Forsskal) in a deep flow technique system Agriculture Water Management 95, 607e615 Jampeetong, A., Brix, H., 2009 Nitrogen nutrition of Salvinia natans: effect of inorganic nitrogen form on growth, morphology, nitrate reductase activity and uptake kinetics of ammonium and nitrate Aquatic Botany 90, 67e73 Jampeetong, A., Brix, H., Kantawanichkul, S., 2012 Effectsof inorganic nitrogen forms on growth, morphology, nitrogen uptake capacity and nutrient allocation
of four tropical aquatic macrophytes (Salvinia cucullata, Ipomoea aquatica, Cyperus involucratus and Vetiveria zizanioides) Aquatic Botany 97, 10e16 Karasu Benli, A.C., Koksal, G., 2005 The acute toxicity of ammonia on tilapia (Oreochromis niloticus L.) larvae and fingerlings Turkish Journal of Veterinary Animal Science 29, 339e344.
Li, W., Li, Z., 2009 In situ nutrient removal from aquaculture wastewater by aquatic vegetable Ipomoea aquatic vegetable Ipomoea aquatica on floating beds Water Science and Technology 59, 1937e1943.
Petrucio, M.M., Esteves, F.A., 2000 Influence of photoperiod on the uptake of ni-trogen and phosphorus in the water by Eichhornia crassipes and Salvinia auriculata Review of Brasilia Biology 60, 373e379.
Phillips, T.A., Summerfelt, R.C., Clayton, R.D., 1998 Feeding frequency effects on water quality and growth of walleye fingerlings in intensive culture Progressive Fish-Culturist 60, 1e8.
Rakocy, J.E., Bailey, D.S., Shultz, K.A., Cole, W.M., 1997 Evaluation of a commercial-scale aquaponic unit for the production of tilapia and lettuce In: Fitzsimmons, K (Ed.), Tilapia Aquaculture: Proceedings of the Fourth International Symposium on Tilapia in Aquaculture at Orlando, Florida Northeast Regional Agricultural Engineering Service, Ithaca, New York, USA,
pp 357e372.
Rakocy, J.E., Masser, M.P., Losordo, T.M., 2006 Recirculating Aquaculture Tank-Production Systems: Aquaponics e Integrating Fish and Plant Culture Southern
Trang 8Riche, M., Haley, D.K., Oeetker, M., Garbrecht, S., Garling, D.L., 2004 Effect of feeding
frequency on gastric evacuation and the return of appetite in tilapia
Oreo-chromis niloticus (L.) Aquaculture 234, 657e673.
Sawyer, C.N., McCarty, P.L., Parkin, G.F., 2003 Chemistry for Environmental
Engi-neering and Science, fifth ed McGraw-Hill, New York.
Seawright, D.E., Stickney, R.R., Walker, R.B., 1998 Nutrient dynamics in integrated
aquaculture-hydroponics systems Aquaculture 160, 215e237.
Solorzano, L., 1969 Determination of ammonia in natural waters by the phenol
hypochlorite method Limnology and Oceanography 14, 700e801.
Stickney, R.R., 1979 Principles of Warmwater Aquaculture John Wiley and Sons Inc.,
New York, NY, USA, p 375.
Strickland, J.D.H., Parsons, T.R., 1972 A practical handbook of seawater analysis Fishery Research Board of Canada Bulletin 167, 310.
Tucker, B.J., Booth, M.A., Allan, G.L., Booth, D., Fielder, D.S., 2006 Effects of photo-period and feeding frequency on performance of newly weaned Australian snapper Pagrus auratus Aquaculture 258, 514e520.
Urbanc-Bercic, O., Gaberscik, A., 1989 The influence of temperature and light in-tensity on activity of water hyacinth (Eichhornia crassipes (Mart.) Solms.) Aquatic Botany 35, 403e408.
Zhou, Z., Cui, Y., Xie, S., Zhu, X., Lei, W., Xue, M., Yang, Y., 2003 Effect of feeding frequency on growth, feed utilization, and size variation of juvenile gibel carp (Carassius auratus gibelio) Journal of Applied Ichthyology 19, 244e249 J.-Y Liang, Y.-H Chien / International Biodeterioration & Biodegradation 85 (2013) 693e700
700