3. Results
3.1. Abalone unit Average water temperature in the abalone tanks ranged from 208C in winter to 288C
in summer. Levels of pH, oxygen and salinity were stable throughout the year and ranged between 7.4–7.6, 7.8–8.8 mg l
-1
and 40–41 ppt, respectively. Growth rate by weight slowed as the animals grew larger, but growth rate by length
Ž was lower in juveniles of the larger size than in small juveniles and in adults Table 1;
. Ž
. Fig. 2 . From October 1995 to December 1996 the juvenile abalone Group I more then
Ž .
tripled their length and multiplied their weight by nearly 30 fold Table 1 . They increased their weight on averaged by nearly 1 day
y1
and their length by 66.5 mm
y1
Ž .
day . Their FCR was above 5 and the survival 75. The adult abalone Group II
Ž .
increased 25 in length and doubled their weight in half a year Table 1 . Daily growth averaged only 0.34 by weight, but nearly equalled the juveniles’ length increase at 59
mm day
y1
. FCR of the adults was nearly triple that of the juveniles, 14.2, but survival Ž
. was better, at 95. The juveniles in the second period Group III gained in weight
nearly 8 fold and doubled their length in 224 days. Their daily growth averaged about the same as that of the juveniles from Group I, at nearly 1, while their length increased
y1
Ž .
on average by only 40 mm day Table 1 . Their FCR was intermediate between those
Ž .
y1
of the other two groups Table 1 . The total abalone yield was 9.4 kg year , with 40
Ž .
meat and meat dw protein content of 75 1 mean sd, n s 4 . 3.2. Fish unit
Average water temperature in the fish tank ranged from 19.18C in winter to 27.98C in summer. Salinity levels were constant throughout the year at 41 ppt. The pH levels
ranged between 7.1–8.0. Oxygen levels were relatively low and ranged between 2.5–6.3
y1
Ž
y3
. mg l
. Annual fish production was 28 kg 35 kg m . The fish grew in a year from 40
Ž .
g to commercial weight of 470 g, but growth was slow in the summer months Fig. 3 .
y1
Ž Average growth was 0.67 day
, FCR averaged 2 and the survival was 95 Table .
1 . 3.3. Seaweed unit
Water temperature in the seaweed tanks ranged from 18.18C in winter to average temperature of 31.28C in summer. Salinity was stable and at 41 ppt throughout the year.
Ž .
Ž
y1
. The daily levels of pH 8.5–8.9 and dissolved oxygen 8.9–9.07 mg l
were high, as typical for intensive photosynthetic culture. U. lactuca grew at a stable rate throughout
Ž .
the year, yielding on average 233 g fresh weight a day and 78 kg annually Fig. 4 . dw Ž
. protein in this seaweed averaged 28 4
n s 4 . Only 46 of the yield was transferred to the abalone, the rest was harvested.
Annual production of G. conferta was poor, only 14 kg, of which half was in useless Ž
. fragments Fig. 4 , because of frequent culture crashes. dw protein content of this
Ž .
seaweed averaged 33 3 n s 4 . The useful yield was given to the abalone, with the additional import of over 5 kg from another system.
A. Neori
et al.
r Aquaculture
186 2000
279 –
291 284
Table 1 Ž
.
a
Growth parameters meansd measured for the abalone and the fish in the integrated mariculture system Initial weight
Final weight Initial length
Final length SGR
Growth FCR
Survival
y1 y1
Ž . Ž .
Ž .
Ž .
Ž .
Ž .
Ž .
Ž . g
g mm
mm day
mm day fwrfw
Ž .
Abalone I 374 days 0.230.04
6.71.1 11.32.3
36.24.4 0.93
66.5 5.16
75 Ž
. Abalone II 184 days
15.74.6 32.34.7
44.22.1 55.15.2
0.34 59
14.2 95
Ž .
Abalone III 224 days 0.70.11
5.50.3 16.63.1
33.73.7 0.92
40 8.26
85
b
Ž .
Fish 374 days 40.45.1
47025 NA
NA 0.67
NA 2
95
a
Ž .
Ž .
See detailed comparisons with published data in Shpigel et al. 1993 and in Table 2 of Shpigel et al. 1996 .
b
dw feed per fw yield.
Ž .
Ž .
Ž .
Fig. 2. Abalone average sizes sd during the experiment. Abalone Group I l ; Abalone Group II ; Ž .
Abalone Group III X .
3.4. Ammonia monitoring The two daily values of ammonia electrode readings in each compartment were
Ž .
averaged daily and then monthly Fig. 5 . Inflow ammonia concentration was negligible, and the abalone added only a little ammonia to the water. The fish compartment
produced the bulk of the ammonia, which was then consistently removed by both seaweed tanks.
Ž .
Ž . Ž
. Fig. 3. Average weight per fish v and growth rate sd of the fish during the experiment.
Ž .
Ž .
Fig. 4. Seaweed cumulative yields during the experiment. U. lactuca l and G. conferta v .
3.5. Nitrogen transformations and budgets Ž
. The analytical autoanalyser nitrogen data from three sampling dates, in April, July
and November, have been averaged and condensed into four nitrogen budgets, one for
Fig. 5. Daily monitoring of ammonia concentrations in the water, averaged for each month, at the different compartments of the integrated mariculture system. Measurements were taken with an ammonia electrode.
Ž .
Ž .
Ž . Ž
. Ž
. Inflow from the sea l ; abalone effluents B ; fish effluents sd
; Gracilaria effluents v ; UlÕa Ž .
effluents X .
each of the three culture compartments and the fourth for the entire integrated culture Ž
. system Table 2 .
3.5.1. Abalone unit N-budget The only significant N input to this unit was seaweed protein. The abalone assimi-
Ž .
lated nearly 40 of this input N Table 2 . Over 60 of the input was unassimilated nitrogen, released from the abalone vessels as ammonia, feces and mucus.
3.5.2. Fish unit N-budget The major N input to the fish tank was protein in the feed as well as a small quantity
Ž .
as dissolved N from the abalone tanks Table 2 . The fish assimilated nearly 20 of this
Table 2 Nitrogen budgets of each unit of the integrated mariculture system and of the whole system
y1 y1
Unit N-form
kg year g N year
Abalone Seaweed input
47 410
100 Abalone harvest
9.4 154
38 Effluent ammonia
15049 37
Feces and mucus 107
26 Deficit
y1 Fish
Feed input 54
3918 96
Influent ammonia 150
4 Fish harvest
28 768
19 Effluent ammonia
1879189 46
Feces 392
10 Deficit
1030 25
Seaweed: UlÕa Influent ammonia
939 100
Harvest 78
629 67
Effluent Ammonia 19514
21 Deficit
116 12
Seaweed: Gracilaria Influent ammonia
939 100
Harvest 7
67 7
Fragments 7
67 7
Effluent ammonia 19941
21 Deficit
607 65
Whole System Feed input
54 3918
100 Fish yield
28 768
19 Fish feces
392 10
UlÕa yield 78
629 16
UlÕa exported 42
339 8.6
Gracilaria yield 14
134 3.4
Gracilaria discarded 7
67 1.7
Gracilaria imported 5.6
53 1.4
Abalone yield 9.4
154 3.9
Abalone feces and mucus 107
2.7 Ammonia in effluents
39354 10
Deficit 1805
46
quantity. Fifty six of the input was unassimilated nitrogen, released from the fish tank as ammonia and feces. A deficit of 25 was presumably comprised of unmeasured
Ž .
forms of combined nitrogen nitrite, nitrate and DON, see Krom et al., 1995 , algal Ž
. growth on the walls and loss to denitrification Dvir et al., 1999 .
3.5.3. Seaweed units N-budgets Both seaweed tanks received equal amounts of nutrients. The UlÕa tank harvest
Ž .
removed on average 67 of its ammonia input Table 2 . The Gracilaria tank
Ž performed inadequately, because of frequent frond disintegration as in Neori et al.,
. 1998 . This resulted in an N deficit that constituted about 16 of the input to the entire
integrated system. The Gracilaria deficit presumably consisted of algal growth on the walls, seaweed fragments, nitrate and DON.
3.5.4. Budget of the entire integrated system Ž
. The overall N-budget of the system Table 2; Fig. 1 has fish feed as its major input.
Ž .
The outputs are of three categories: harvests fish, abalone, exported seaweed , ammonia Ž
in the seaweed effluents and a deficit consisting of unmeasured entities of dissolved N, .
particulate N, algal growth on the walls and denitrification . About a third of the deficit was contributed by the frond fragmentation in the Gracilaria culture.
Ž .
The harvest category, 38 of the N input, consisted of fish 19 , seaweed Ž
. Ž
. 19, over half of it in exported and discarded biomass N and abalone 4 .
Had both seaweed tanks cultured UlÕa, the exported seaweed would have increased to 32 and the deficit would have dropped below 30.
4. Discussion