Prospecção de áreas propícias para o cultivo de macroalgas na região da costa negra, Ceará, Brasil

Abstract

The aims of this thesis was to verify the potentiality and to prospect of suitable areas for the farm of the seaweed Gracilaria birdiae in the region of Costa Negra, west coast of the state of Ceará, Brazil. Experimental cultures were carried out in long line systems in two beaches of the region, namely Lagoa da Volta and Volta do Rio, where the performance indicators were followed: weight gain (g), biomass gain (kg) and Specific growth (% of weight.day-1). During the growing experiment from, June 9th to July 24 2016 (45 days), the following indicators were monitored: turbidity (FNU), total dissolved solids (mg.L-1), electrical conductivity (mS.cm-1), pH, water temperature (°C), salinity, Secchi transparency (cm), rate of oxygen saturation (%) and dissolved oxygen concentration (mg.L-1), current velocity (m.s-1) and wind velocity (m.s-1). Using the last six environmental indicators, the novel Aptitude to Algiculture Index (IAA) was proposed, which used a scale of aptitude to algiculture divided into five levels according to the score obtained: Low Apt (0 - 32), Apt (33-66) and High Apt (67-100). From the IAA method, an application for mobile devices was developed in order to be used with a tool to aid in the exploration of the algiculture areas in the region studied. As a result of the experimental farms, as well as the IAA results, it was observed that the Beach of Lagoa da Volta provided better conditions for macroalgae farm, and the results of performance were about 2.5 times better in relation to Beach of Volta do Rio were classified as Low Apt according to the IAA classification, however, the values obtained in the first one were higher than in the latter, corroborating with the results of the experimental cultures. The results of the prospection of new areas for agriculture with the use of the IAA application, presented the following results according to the proposed aptitude scale: Beach of Barrinha was classified as Very Apt (72.46 points); Beach of the Patos (53,06 points), Beach of Almofala (50,95 points), Beach of the Island of the Coqueiros (44,22 points), Beach of Arpoeiras (42,72 points) 59 points), Beach of Torrões (38.23 points), Beach of Preá (36.21 points) and Beach of Espraiado (34.93 points) classified as Apt and Beach of Imburanas (29.93 points) classified as Little Apt. In conclusion, we can say that it is possible to cultivate macroalgae in the studied region, the IAA proved to be effective in your evaluation, pointing to the area with the highest potential, the same one that obtained the best farm result. The IAA application proved to be a useful tool in the exploration of new areas for algicutura, informing level of aptitude on site. The prospection on the 10 beaches visited in the region of Costa Negra, besides the two that were studied, pointed out that Beach of Barrinha is the one with the greatest aptitude for algiculture. Further studies are recommended to confirm the effectiveness of the IAA, as well as improvements to the applicative.