Monitoring of Kappaphycus alvarezii: a case study in the municipality of Pitimbu–PB

The cultivation of marine algae, especially red macroalgae, has grown significantly in recent decades, becoming an important source of raw material for various commercial sectors. The species Kappaphycus alvarezii has been used in this context, but this introduction into natural areas can represent ecological risks. This study seeks to evaluate if there is evidence of natural colonization of Kappaphycus alvarezii on reefs near cultivation areas and if this activity affects local reef cover. Three sampling areas were analyzed: one with a history of cultivation of the species and two control areas, all belonging to the same reef complex in the municipality of Pitimbu, Paraíba. Data collection was realized by underwater images (photoquadrats), subsequently analyzed with the CoralNet system, complemented by manual species inventory. Analyses compared the total macroalgae cover and diversity between areas, using the Shannon index. The results showed no evidence of Kappaphycus alvarezii adhering to natural substrates or reproductive structures of the species. These findings indicate a low potential for ecological invasion, suggesting that algae cultivation can be viable under appropriate environmental management practices. However, the current legislation prohibiting cultivation in the Northeast region needs to be reviewed, considering the results obtained and the possibility of sustainable use of the species.