Comparing the Effectiveness of Bamboo Floats and Plastic Bottles in Vertical Cultivation of Kappaphycus alvarezii for Mitigating Marine Debris Pathways: An Insight into Eco-Friendly Seaweed Aquaculture

The cultivation of seaweed is a subject of an ongoing debate due to its potential to provide ecosystem services and, concurrently, to serve as an entry point for marine debris, notably through the use of plastic bottle floats. This study aimed to compare the efficacy of bamboo floats against plastic bottles in the cultivation of Kappahycus alvarezii, with the objective of discerning their potential in mitigating marine debris pathways. Two types of float materials, each comprising three construction units, were devised for the vertical cultivation method over a 42-day period. Each construction unit, measuring 2 × 5m, incorporated three stretching ropes, fifteen hanging ropes, and 45 propagules planted vertically (at the top, middle, and bottom). The floats were constructed using either 330mL mineral water plastic bottles and 10cm long segments of used building construction bamboo, with 18 units of each type employed. The construction unit was designed to adopt a zigzag pattern between the bamboo float unit and the plastic bottle. Biomass production and semi-refined carrageenan (SRC) content of K. alvarezii were employed as indicators for evaluating float performance. The results indicated that there was no statistically significant difference in biomass production and SRC between the two float types (P> 0.05). The findings of this study suggested that bamboo holds the potential to replace plastic bottles as floats in seaweed cultivation, offering a promising avenue to mitigate marine debris pathways in sustainable mariculture.