Alginate-based hydrogels as a new alternative for control of the invasive coral Tubastraea coccinea Lesson, 1830

Alginate-based hydrogels as a new alternative for control of the invasive coral Tubastraea coccinea Lesson, 1830

Matheus da Silva Barbosa^a, Suelen Gauna Trindade^a, Luciana V. R. de Messano^b; Luciana Altvater^b; Ricardo Coutinho^b; Carlos Speglich^c, Edvaldo Sabadini^a,*

1. Department of Physical-Chemistry, Institute of Chemistry, University of Campinas, P.O. BOX 6154, 13084-862, Campinas, São Paulo, Brazil. Telephone: +55 19 3521313.
2. Department of Marine Biotechnology, Institute of Marine Studies Admiral Paulo Moreira, IEAPM – Rua Kioto 253, Arraial do Cabo, RJ, Brazil. Telephone: +55 22 26229012.
3. PETROBRAS Research Center – CENPES, Rio de Janeiro, RJ, Brazil

The widespread movement of ships often introduces invasive species that pose a threat to native ecosystems, potentially causing significant environmental and socioeconomic impacts. One such invader is the sun-coral (Tubastraea spp), originally from the Indian-Pacific Ocean, which has been introduced to the Atlantic Ocean and is rapidly spreading due to its competitive abilities and lack of natural predators [1]. To address this invasion while minimizing harm to coexisting species in the region, in this work researchers have developed a hydrogel based on alginate and acetic acid. We show that this hydrogel reduces the pH at the contact site, effectively eliminating the sun-coral after short exposure periods (Figure 1). Alginate was chosen as the polymeric matrix due to its biodegradability and the ability to modulate its mechanical and rheological response.

Additionally, this study proposes a management methodology for sun-coral using a remotely operated vehicle (ROV) to apply the biocidal formulation, covering all colonies (Figure 2). A calcium solution is also applied to crosslinking the polymer and enhance the hydrogel's resistance to shear stress caused by seawater movement. This approach can surpass manual coral removal by divers, the current management strategy [2]. It is efficient, highly localized, prevents larval release associated with coral handling, and eliminates risks to diver safety. Moreover, it allows for application in offshore environments.

To assess the scalability and real-world feasibility of this technology, a mobile system for hydrogel preparation and pumping was developed (Figure 3). The methodology was tested in two pilot trials: one at a port structure in Arraial do Cabo and another at a docked drilling platform in Angra dos Reis, Rio de Janeiro, Brazil.

References

[1] J. C. Creed, B. P. Masi, and M. C. Mantelatto, Biol Invasions, vol. 21, pp. 1227–1247, 2019.

[2] R. dos S. Costa et al., Ocean Coast. Res., vol. 70, pp. 1–7, 2022.