Marine cultivation of the red alga Gracilaria birdiae at Icapuí county, Ceará State

Abstract

The extraction of seaweed due to global demand for phycocolloids by industries has affected the sustainability of these marine resources, as the result of need and lack of knowledge related to mariculture in Brazil. This study aimed to evaluate the performance of red marine alga Gracilaria birdiae cultivated in the coastal zone of Icapuí, Ceará, Brazil, from September to November 2006. Seedlings (100±5.84 g) previously selected from a natural bank were grown during 56 days in long-line structures. Every 15 days, weight gain and Relative Growth Rate - RGR (% day-1) of the algae were assessed. The results showed a high correlation (r = 0.99; p < 0.05) between the time of cultivation and the average weight of the algae. However, average daily temperature showed a low correlation (r = 0.420) with biomass gain, possibly due to lower water transparency resulting from the proximity of coastal structures. Mean RGR was 3.44% day-1 after 56 days of cultivation; this growth can be improved over an annual monitoring period.