Inferring functional traits in a deep-sea wood-boring bivalve using dynamic energy budget theory

S Lefebvre,S M Gaudron,G M Marques

doi:10.1038/s41598-021-02243-w

Abstract

For species in the deep sea, there is a knowledge gap related to their functional traits at all stages of their life cycles. Dynamic energy budget (DEB) theory has been proven to be an efficient framework for estimating functional traits throughout a life cycle using simulation modelling. An abj-DEB model, which compared with the standard DEB model includes an extra juvenile stage between the embryo and the usual juvenile stages, has been successfully implemented for the deep-sea Atlantic woodeater Xylonora atlantica. Most of the core and primary parameter values of the model were in the range of those found for shallow marine bivalve species; however, in comparison to shallow marine bivalves, X. atlantica required less energy conductance and energy to reach the puberty stage for the same range of body sizes, and its maximum reserve capacity was higher. Consequently, its size at first reproduction was small, and better survival under starvation conditions was expected. A series of functional traits were simulated according to different scenarios of food density and temperature. The results showed a weak cumulative number of oocytes, a low growth rate and a small maximum body size but an extended pelagic larval duration under deep-sea environmental conditions. Moreover, DEB modelling helped explain that some male X. atlantica individuals remain dwarfs while still reproducing by changing their energy allocation during their ontogenetic development in favour of reproduction. The estimation of functional traits using DEB modelling will be useful in further deep-sea studies on the connectivity and resilience of populations.

Highlights

For species in the deep sea, there is a knowledge gap related to their functional traits at all stages of their life cycles
The maximum assimilation rate pAm of X. atlantica was twofold lower than those of shallower marine bivalve species but ten- to 15-fold higher than that of the symbiotic shallow marine bivalve Thyasira cf. gouldi that relies on food both from its sulfur-oxidizing bacteria and POM33. pAm is linked to maximal structural body size (Lm), where X. atlantica had a greater Lm than that of the thiotrophic bivalve T. cf. gouldi
A Dynamic energy budget (DEB) model conducted for a deep-sea benthic species (Xylonora atlantica) was developed successfully for the first time, revealing specific adaptations to deep-sea and wood-fall habitats, this species has traits in common with shallow water marine bivalves

Summary

Introduction

For species in the deep sea, there is a knowledge gap related to their functional traits at all stages of their life cycles. A blueprint on the accomplishments needed for the decade was established by an international workgroup of experts in deep-sea biology and ecology, and some of the priority measurements needed were feeding regime, growth rate, longevity, fecundity, size at puberty, maximum body size and pelagic larval duration for benthic and pelagic deep-sea macro- and megafauna[2] This fundamental knowledge is necessary for understanding the connectivity and resilience of species populations and trophic network interactions in the ocean. A DEB model quantifies the energy allocation to reproduction (or acquisition of complexity) and growth of a species according to environmental conditions such as temperature and food availability at any stage of its life cycle[16]. Questions remain regarding how these tiny specimens of X. atlantica were able to reproduce having the size of young juveniles

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