Efeito de diferentes intensidades de luz no sistema de cultivo integrado de ulva fasciata (Ulvaceaem, Chlorophyta) e o peixe-palhaço Amphiprion Ocellaris

Abstract

The objective of this study was to analyze, through experiments in microcosms, the reduction and/or removal of residues with Ulva fasciata in an integrated system, with the cultivation of clownfish Amphiprion ocellaris, using different light intensities. 50L aquariums were used with a density of 10 fish/aquarium, (Tl = 2.73cm±0.02cm and Tw = 0.38g±0.009g), with an 8L superimposed tray, for the cultivation of U. fasciata, with initial weight 150g per experimental unit. The aquariums received constant aeration, being maintained at a temperature of 23oC and a salinity of 30. Three different light intensities were tested, with three replicates for each treatment, during 12 hours of artificial light/day. It was tested: cultivation of A. ocellaris with Ulva, with 1 lamp =16.4k lux (low light intensity - A); cultivation of A. ocellaris and Ulva, with 2 lamps =22.5k lux (intermediate light intensity - B); cultivation of A. ocellaris and Ulva, with 3 lamps =29.8k lux (high light intensity - C); and controls: Ulva cultivation, with low light intensity - D; cultivation of Ulva with intermediate light intensity – E; and cultivation of Ulva with high light intensity - F. The pH varied from 7.6-8.5 and from 28 days onwards it decreased, with no significant difference between treatments. In the control, the pH pattern remained similar to those in experiments with the presence of fish. The TSD ranged from 77.5-89.0mg/l, decreasing on days 7-14. The TSD in controls showed a gradual decrease except in the E treatment at 35 days. The OD for the three treatments increased over the 42 days, ranging between 5.6-6.6mg/l. In the control, there was a slight reduction in OD from 14 to 28 days. NH3 increased gradually from 28 days onwards with 0.004mg/l. NO2- reached averages of 2.4 mg/l at 42 days, being higher in treatments A. NO3- did not show a significant difference between treatments and days of experiments. In control treatments, the values of NH3, NO2-, NO3-and PO43- remained close to zero. The survival percentage of A. ocellaris in the entire experiment was 100%. The condition factor (K) was higher in treatments A and B. K showed a negative correlation with pH and TSD and a positive correlation with OD, NH3; NO2- and PO43-. K showed no significant difference with NO3- content. Higher Ulva biomass occurred during 21 days for treatment C, followed by treatments B and A. Biomass did not show a significant correlation with OD, NH3, NO2- and NO3-, but showed a positive correlation with PO43- and a negative correlation with the TSD. In controls, treatment F maintained the highest biomasses. The highest TC occurred in the first two weeks, for treatment C. TC did not show a correlation with OD, TSD, NH3, NO2- and NO3-, but apositive correlation with pH and a negative correlation with PO43-. In the control group, TC was elevated for up to 21 days, decreasing later. The integrated cultivation between U. fasciata x A. ocellaris was efficient in both cultivars, however with different light intensity demands. The performance of the fish responded better to treatments A and B. The pH levels with low alkalinity and lower TSD favored fish cultivation. On the other hand, macroalgae developed well in treatment C during the first three weeks of the study, exhibiting greater bioremediation effects on water quality. After this period, the increase in biomass triggered competition for irradiance, favoring its degradation due to the increase in PO43- and TSD and the reduction in pH. The results obtained are essential for the management and exploitation of these species, whose applications range from innovations in Aquaculture to the forefront of environmental remediation strategies.