Effect of phytoplankton and temperature on the reproduction of the Pacific oyster Crassostrea gigas: Investigation through DEB theory

Abstract

DEB theory can be used to obtain a detailed description of energy allocation in organisms and the control of this allocation by temperature and food concentration. In this study, we modified the model of Bourlès et al. (2009) developed for the Pacific oyster, Crassostrea gigas, to improve the description of reproductive effort. The model was amended in two ways: a new set of parameters was incorporated and a full description of gonad construction in spring was added, with a new state variable. The application of this model to a dataset for oyster growth measured in four bays over two years showed that this model better described reproductive effort, without modifying overall growth dynamics. We then explored the reproductive responses of oysters to their environment in greater detail, by applying this new version of the model with the theoretical forcing variables of phytoplankton concentration and temperature. Spawning time was found to be driving principally by yearly mean temperature, and reproductive effort was found to depend mostly on the half-saturation coefficient of the functional response. These results highlight the importance of the half-saturation coefficient and provide additional support for field research on the food preferences of oysters. Highlights ► We developed an improved version of the DEB model for Pacific oyster, C. gigas. ► This model is used to give a deep insight into the ecophysiology of reproduction and the ecology of this species. ► It gives another utilization of the DEB theory as a tool to better understand ecology processes.

Numerical modelling of spatio-temporal variability of growth of Mytilus edulis (L.) and influence of its cultivation on ecosystem functioning

“…Handå et al, 2011;Filgueira et al, 2011;Maar et al, 2009;Rosland et al, 2009Rosland et al, , 2011Saraiva et al, 2011a;Thomas et al, 2011;van der Veer et al, 2006), Crassostrea gigas (e.g. Alunno-Bruscia et al, 2011;Barillé et al, 2011;Bernard et al, 2011;Bourlès et al, 2009;Emmery et al, 2011), and other species. Several authors have dynamically coupled DEB models with biogeochemical models to provide feedbacks from aquaculture farms to phytoplankton and nutrient dynamics.…”

Disruption of amylase genes by RNA interference affects reproduction in the Pacific oyster Crassostrea gigas

“…On examining the median part of the visceral mass, Royer et al (2008) found the percentage surface occupied by the gonad to be directly linked to the number and/or size of gametes produced and therefore representative of reproductive effort, which is linked to the proportion of energy allocated to reproduction (Todd and Havenhand, 1983;Normand et al, 2009). In the DEB theory, oyster reproductive effort was found to depend mostly on the halfsaturation coefficient for ingestion (Bernard et al, 2011). This environment-specific coefficient reflects quantitative and qualitative variability in the oysters' food (Alunno-Bruscia et al, 2011).…”

“…The DEB model describes four state variable dynamics: the energy stored in reserves, E, the energy allocated for structural growth, E V , the energy allocated to development and reproduction, E R , and the energy used in the construction of gametes, E GO (see Bernard et al, 2011 for full description). In the DEB model, a constant fraction, κ, of the energy mobilized from the reserves is allocated to growth and structural maintenance, the remainder (i.e.…”

“…A constant proportion of ingested energy is assimilated according to the absorption efficiency (also known as assimilation efficiency AE, %). The model formulation and parameter values used here are based on the study of Bernard et al (2011).…”

“…Pouvreau et al, 2006;Alunno-Bruscia et al, 2011). The recently improved version of the DEB model for C. gigas focused on the description of reproduction-related features and permitted a description of energy allocation to the gametogenesis and resorption processes (Bernard et al, 2011). Beyond the description of effects of variability in environmental forcing on energy intake and use, the DEB model appears to be a valuable tool for studying disturbance in individual energetics (Kooijman and Bedaux, 1996).…”