An eco-friendly strategy using flax/polylactide composite to tackle the marine invasive sponge Celtodoryx ciocalyptoides (Burton, 1935)

Abstract

Summary: Discovered in the 1990s in the river of Etel (Morbihan, France), the marine invasive sponge Celtodoryx ciocalyptoides originating from the Chinese Yellow Sea is now well implanted on concrete pilings inside the Etel marina (Morbihan, France). Novel eco-friendly strategies are urgently needed in order to limit its adhesion on concrete and the risk of dispersal outside the marina. In this study, the anti-settlement and anti-attachment properties of flax/PLA, a biocomposite made of polylactide reinforced with flax fibres, were evaluated on sponge propagules’ behaviour. First, flax/PLA panels were immersed into the Etel marina for six years. The coverage onto PLA panels of marine invertebrates was estimated twice a year. In a second step, PLA panels were used as artificial support for invasive sponge transplants. In comparison, specimens were transplanted in mesh bags. Sponge weight increase was measured twice a year. Results indicated that the occurrence of the invasive sponge was delayed for two years on biocomposite in comparison with concrete. At the end of the six-year study, macrofouling by marine invertebrates did not exceed 70% of the surface of the panels and no C. ciocalyptoides specimens were observed. Once transplanted on PLA panels, sponge specimens were able to survive the first year without growing. After two years, none of the transplants survived while specimens in mesh bags increased their weight by 100%. These findings highlight the potential interest of biocomposite in the development of coastal and marine infrastructures. Keywords: Artificial substrate, Biocomposite, Celtodoryx ciocalyptoides, Marine invaders, Polylactide