Data/hora: 10/06/2024 08:12:06

Provedor de dados: | 5
País: | France
Título: | Modélisation de la dynamique du microphytobenthos des vasières intertidales du bassin de Marennes-Oléron. Effets des synchroniseurs physiques sur la régulation de la production
Autores: | Guarini, Jean-marc.
Data: | 1998-04-06
Ano: | 1998
Palavras-chave: | Microphytobenthos; Vasière intetidale; Modélisation; Dynamique de la biomasse; Expérimentation; Ecophysiologie; Couplage physique/biologie; Microphytobenthos; Intertidal mudflat; Modelling; Dynamics of the biomass; Experimentation; Ecophysiology; Physics/biology coupling.
Resumo: | The study aimed at quantifying the spatio-temporal evolution of microphytobenthic biomass in intertidal mudflats of Marennes-Oléron Bay. To reach this goal, a dynamic model has been proposed, including processes of primary production, active migration of epipelic diatoms and biomass lasses due to mortalities on one hand and resuspension in the water column during submersion on the other hand. The spatialisation is given by a hydrodynamic madel which calculates the water height everywhere. The photic environment of microphytobenthos is described in a discrete way, by means of two layers: the biofilm of epipelic algae « S »on the top of the sediment and the fust centimeter of the mud « F ». The endogenous vertical migration rhythm of epipelic algae controls the cell exchange between both layers: (i) an upward movement from F to S during the diurnal exposure period and a downward movement from S to F during night exposure and submersion periods. Because of this behavioural difference, two systems of ordinary differentiai equations have been formulated. During the diurnal exondation, only microalgae at the surface are able to photosynthesize at the level of the incident radiations. However, the number of cells in S is limited, and the exchanges from F to S are density-dependent. Production processes were studied experimentally; particularly, the shortterm temperature effect on the microphytobenthic photosynthetic capacity (Pmax) was quantified. In relation to it, a madel of the Mud Surface Temperature dynamics was developped to analyse the spatio-temporal dynamics of MST and Pmax. It was thus found out that microalgal photosynthesis exhibited thermo-inhibition during summer on mudflats. Loss terms were frrst considered to be global and were formulated as linear functions of the microphytobenthic biomass. It is shown that such a system, with fast commutations from one state to the other, reaches a cyclic equilibrium which was further validated by observed data series. In addition, the model reproduces the characteristics of the local seasonal dynamics and particularly the decrease of biomass in summer. However, the loss processes were not defmed weil enough to allow an accurate representation of the observed spatial structures. Sorne theoretical developments are proposed to improve the model formulation ; such new perspectives call for additional experiments in conjunction with the modelling approach. So, the existing system of equations can be used as a basis for future developments with the aim of testing hypotheses about microphytobenthos dynamics.
Tipo: | Text
Idioma: | Francês

Identificador:

http://archimer.ifremer.fr/doc/00439/55029/56462.pdf

http://archimer.ifremer.fr/doc/00439/55029/

Editor: | Université Pierre &amp; Marie Curie
Formato: | application/pdf

Fonte:

1998 Université Paris 6

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