Simulation of the mollusc Ascoglossa Elysia subornata population dynamics: application to the potential biocontrol of Caulerpa taxifolia growth in the Mediterranean Sea

A multi-modelling simulation was performed to assess the potentialities of a biocontrol of the alga Caulerpa taxifolia (Valhl) C. Agardh by the Ascoglossa Elysia subornata (Verrill, 1901) in the Mediterranean Sea. With this aim in view, the biological and ecological parameters considered as key factors were identified in order to present a state of the art on biological and ecological parameters related to the behaviour of E. subornata toward C. taxifolia and toward the Mediterranean conditions. To this end, growth, survival, reproduction, feeding on C. taxifolia and foraging of E. subornata are studied. Simulations, taking into account spatial effects, give encouraging results and show that additional experiments in large mesocosm may be engaged to improve the actual knowledge of Elysia behaviour, the impact on C. taxifolia, the trophic relationships, etc. The results of simulations demonstrate that the greatest impacts on Caulerpa are obtained using either some adults or mixing adults and juvenile slugs. In any case, better results are obtained by a scattering of slugs on isolated spots rather than on clusters (with constant surfaces). Lastly, the choice of a suitable date for scattering increases the weak consumption of Caulerpa resulting from the scattering of juvenile slugs.