Avaliação do crescimento da alga marinha gracilaria birdiae (gracilariales, rhodophyta), cultivada em estrutura de long-line

Abstract

To present dissertation it analyzes the effect of the brightness in the growth of the alga sea Gracilaria birdiae through the rate of specific growth (TCE) and biomass increase in different depths. A structure of the type long-line was used with main rope measuring 25m and 10 sec ondary strings of 2,5m installation to 200m of the coast with depth between 5m and 6m (tide evaporates). 12 seedlings were fastened by secondary rope with spacing of 20cm composing 12 depth lines. With 30 days it accomplished the measure of the weights of the seedlings of the structure identified by secondary rope and depth line. With 60 and 90 days the measure of the weights was just in the depth lines that presented seedlings in better physical conditions. In the tested depths from 0,2 to 2,4m, it was observed a better acting of the growth as well as better appearance and physical condition of the fastened seedlings from 0,2m to 1,2m, while fastened them from 1,4m to 1,8m or they had inferior growth or practically they didn't grow , and fastened them in the inferior limit from 2,0 to 2,4m reduced growth of the seedlings it was verified. The obtained medium weights presented significant statistical difference (F = 187,104; p = 0,05). TCE demonstrated negative correlation with the dept h (r = - 0,95; p = 0,05; n = 120). In the closest depths of the surface from 0,2 to 0,6m favored the growth of the algae reaching weights from 167,5 to 147,0g and TCE 2,92 and 2,69% day-1, among 0,8m to 1,2m weights from 139,0 to 124,0g and TCE fr om 2,29 to 1,90% day-1, and starting from 1,4m until 2,4m weights from 94,5 to 59,5g and TCE 0,9 to 0,53% day-1. The reduction in the weights below 1,2 m was quite accentuated evidencing that the algae had detriment in your growth with the reduction of the intensity brightness presenting reduced growth of some you change fastened in the extremities of the strings. The parameters of the water in the area of the cultivation temperature, salinity and degree of transparency of the water presented averages of 29,6 ± 2,41ºC, 35,6 ± 1,49‰ and 1,20 ± 0,76m. In the end of the experimental period (90 days) the seedlings reached final weight of 937,0g, ideal for crop. For Gracilaria birdiae, the brightness was the environmental factor that it affected your TCE and biomass production indeed, presenting in the conditions of the cultivation, satisfactory growth until the depth of 1,2m where the seedlings reached weight of 124,0 ± 9,94 g and TCE of 1,90 %dia-1.