Results Directory UMM :Data Elmu:jurnal:A:Aquaculture:Vol186.Issue3-4.Jun2000:

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