Data/hora: 11/06/2024 11:19:21

Provedor de dados: | 5
País: | France
Título: | Effets d’une exposition alimentaire chronique à un mélange environnemental de PCB et PBDE sur les traits d’histoire de vie, la bioénergétique et la dynamique des populations de poissons
Autores: | Horri, Khaled.
Data: | 2018-04-12
Ano: | 2018
Palavras-chave: | Poisson-zèbre; Écotoxicologie; Polluants organiques persistants; Allocation d’énergie; Modes d’action; Dynamique des populations; Populations structurées; Zebrafish; Ecotoxicology; Persistent organic pollutants; Energy allocation; Modes of action; Population dynamics; Structured populations.
Resumo: | Persistent organic pollutants (POPs) are a broad group of compounds with varying physicochemical and toxic properties. Among POP, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are two families of hydrophobic compounds sharing some similar environmental properties such as hydrophobicity, persistence, bioaccumulation and toxicity. Previous studies have demonstrated that these compounds could affect fish life-history traits such as survival, growth and reproductive success. However, few studies have focused on environmental situations as most previous works investigated the effect of either single congeners, or single families of molecules among POP, or high concentrations, so that results can hardly be transposed to natural populations. The present thesis focuses on the evaluation of individual and population responses of fish to a chronic dietary exposure to an environmentally realistic marine mixture of PCBs and PBDEs. It is divided into three parts. The first part aimed to evaluate the effects of an experimental exposure to a mixture of PCBs and PBDEs that is representative of the Seine estuary on the life-history traits of zebrafish taken as a model species. Exposure was conducted through diet from the first meal and throughout the life cycle of the fish. Life-history traits of exposed fish were compared to those of control individuals using several replicate populations in each treatment. The results showed a slower growth, but to a larger asymptotic length, and delayed spawning probability in exposed fish. In addition, offspring issued from early spawning events of exposed fish exhibited a lower larval survival under starvation condition. These results suggest an increase in energy allocation towards growth at the expense of maturation, maintenance and reproduction in exposed individuals, which could correspond to a shift in the energy trade-off between these two compartments. The second part aimed to identify, on the basis of a bioenergetic model, the physiological modes of action (PMoA) of PCBs and PBDEs that can explain the experimental results. A Dynamic Energy Budget (DEB) model was calibrated for each treatment using experimental data and the estimated model parameters were compared between control and exposed fish. The DEB model revealed two potential PMoAs: the first one was through an increase of the fraction of energy allocated to somatic maintenance and growth at the expense of maturation, its maintenance and reproduction and the second one was through an increase of the cost of production of an egg. The third part focused on the population dynamical consequences of the individual life-history effects of the two identified PMoAs of PCBs and PBDEs. A Physiologically Structured Population Model (PSP) was coupled with (i) the DEB model to describe the ontogenetic trajectory of individuals’ life-history traits, and (ii) a dynamic resource model to include the feedback loop between individuals and their resource. The DEB-PSP model predicted a lower abundance and a higher biomass in exposed population compared to control population. These results could be explained by a weaker fecundity that leads to a lower abundance of individuals and an increased growth, which results into a larger biomass by overcompensating the numerical deficit for populations. The bifurcation analysis of the independent effects of the two PMoAs showed that they participate jointly in the decrease of the abundance and the increase of the biomass of the exposed population. The model also predicted that lower intensities of size-independent natural mortality are necessary to drive exposed population to extinction relative to control population, whereas higher intensities are necessary when mortality decreases with size as for predation mortality. When fishing mortality is added to predation mortality and increases with size, as in trawl fisheries, the control population seems to persist at higher exploitation rates than the exposed one. Finally, the exposed population may allow for a larger maximum sustainable yield but at a lower exploitation rate, thus exposing the contaminated population to a higher risk of overexploitation.
Tipo: | Text
Idioma: | Francês

Identificador:

http://archimer.ifremer.fr/doc/00444/55592/57219.pdf

http://archimer.ifremer.fr/doc/00444/55592/

Editor: | Université du Havre
Formato: | application/pdf

Fonte:

2018 Université du Havre

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