engleski

Std instead of abj type DEB model should be assumed when fitting freshwater crayfish ontogeny

Freshwater crayfish have evolved from marine crustaceans, losing a larval (planktonic) stage along the way. This resulted in a shorter and simpler ontogeny compared to their marine relatives: the little crayfish stay attached to their mother after hatching, and at the onset of feeding ("birth" in DEB) they already physically resemble juveniles. Most of the crustaceans in the AmP database are, however, marine decapods, and the prevailing model type for crustaceans is therefore the abj-type DEB model. Unlike the standard model which assumes a constant metabolism throughout the life cycle, the abj model has a slower embryonic phase, with metabolism accelerating between birth and the turning point called metabolic metamorphosis. The metabolic metamorphosis most often (but not always) coincides with physical metamorphosis, i.e., the individual transforming from the larval into the juvenile stage. In this study, we compared performances of abj and std types of DEB model for freshwater crayfish. We applied the std-type model and compared its fit to abj- type model for the two existing freshwater crayfish entries in AmP database (signal crayfish, Pacifastacus leniusculus and noble crayfish, Astacus astacus), as well as for an additional species we added to the database (marbled crayfish, Procambarus viriginalis). For marbled crayfish, we included temperature sensitivity via multi-parameter Arrhenius correction. For all crayfish, we allow for a delay in onset of embryonic development, or a time needed to build up the reserve mobilization pathways - parameter t0. We find that the std model fully describes the ontogeny of freshwater crayfish, resulting in predictions that match the observations of growth (age-length, age- weight), development (age at hatching, birth, puberty), and energetics (initial energy in an egg). We therefore suggest that the simpler std- type model be preferentially used over the abj- type model when fitting parameters for freshwater crayfish.

freshwater crayfish ; metamorphosis ; metabolic acceleration ; model selection

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