Annelid polychaetes experience metabolic acceleration as other Lophotrochozoans: Inferences on the life cycle of Arenicola marina with a Dynamic Energy Budget model

Arenicola marina is a polychaete (Lophotrochozoan) displaying a complex bentho-pelagic life cycle with two larval dispersal phases, only partially described up to now. A Dynamic Energy Budget (DEB) model was applied to the species in order to reconstruct its life cycle and growth under in situ environmental conditions. Two types of DEB models are usually applied to other Lophotrochozoans displaying similar life cycles: the standard (std-) model, applied to polychaetes (5 entries among the 1524 of the Add-my-Pet database on the 18/10/2018), and the abj-model, which includes an acceleration of metabolism between birth and metamorphosis, and which has been applied to most molluscs (77 abj-entries out of the 80 mollusc entries) enabling better fit predictions for the early life stages. The parameter estimation was performed with both models to assess the suitability of an abj-model for A. marina. The zero-variate dataset consisted of length and age data at different life cycle stages, the lifespan, the maximum observed length, and the wet weight of an egg. The uni-variate dataset consisted of two growth experiments from the literature at two food levels and several temperatures, laboratory data of oxygen consumption at several temperatures, and fecundity for different lengths. The predictions of the abj-model fitted better to the data (SMSE = 0.29). The acceleration coefficient was ca 11, which is similar to mollusc values. The field growth curves and the scaled functional responses (as a proxy of food levels) were suitably reconstructed with the new parameter set. The reconstruction of the early life-stages chronology according to in situ environmental conditions of a temperate marine ecosystem indicated a first dispersal phase of 5 days followed by a 7 months temporary settlement before a second dispersal phase in spring, at the end of metamorphosis. We emphasize the need for using abj-models for polychaetes in future studies.