Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 415:141-158 (2010) - DOI: https://doi.org/10.3354/meps08659 Modelling the spatial heterogeneity of ecological processes in an intertidal estuarine bay: dynamic interactions between bivalves and phytoplankton Karine Grangeré1,2,*, Sébastien Lefebvre1,3, Cédric Bacher2, Philippe Cugier2, Alain Ménesguen2 1Université de Caen Basse-Normandie, UMR 100 IFREMER-UCBN PE2M Physiologie et Ecophysiologie des Mollusques Marins, Esplanade de la Paix, 14032 Caen cedex, France 2IFREMER, Département Dynamiques de l’Environnement côtier, Technopôle Brest-Iroise, z.i. Pointe du diable, B.P. 70, 29280 Plouzané, France 3Université de Lille1 sciences et technologies-CNRS UMR 8187 LOG «Laboratoire d’Océanographie et de Géoscience», Station Marine de Wimereux, 28 avenue Foch, 62930 Wimereux, France *Email: karine.grangere@unicaen.fr ABSTRACT: Spatial patterns in ecological communities result from a combination of physical and biological factors. In an estuarine intertidal bay, spatial differences have been found in the structure of phytoplanktonic communities and in the biological performance of cultivated oysters. It has been hypothesised that trophic heterogeneity exists, although the mechanisms controlling it remain undefined. Spatial and temporal interactions in the structure of phytoplanktonic biomass and in the biological performance of cultivated oysters were highlighted in this estuarine intertidal bay using a 2-dimensional hydrodynamic model coupled to a nutrient–phytoplankton–zooplankton bivalve food web model. The coupled models allowed a reproduction in space and time of variations in the main variables (i.e. nutrients, chlorophyll a (chl a) and bivalve growth and reproduction). Spatial patterns of chl a at the bay scale showed a dichotomy between the eastern and western parts of the bay, with a sharp drop in concentrations above the oyster area. At the smallest scale, significant spatial heterogeneity was obtained in terms of oyster dry weight (DW), with a difference of around 3.0 g between the lowest and the highest oyster DW. Influences of physical and biological factors were discriminated for spatial patterns of phytoplankton at a large scale and for spatial patterns of bivalves at a small scale. Bivalve density, immersion time (i.e. feeding time) and current velocity were identified as the main factors controlling the spatial patterns of phytoplankton and bivalve growth. The results of the model indicate that the effects of spatial scales are much larger than those of temporal scales; this conclusion differs from that expected through observations only. Top-down effects of oysters on phytoplankton biomass at local scales were revealed, whereas bottom-up effects drove primary productivity at the whole bay scale. In general, we conclude that spatial modelling is particularly appropriate to reveal spatial properties which would be difficult to observe directly. Knowledge of ecosystem functioning would be enhanced accordingly. KEY WORDS: Spatial heterogeneity · Hydrodynamics · Ecosystem model · Food supply · Bivalves · Dynamic energy budget model · Physiological status · Baie des Veys Full text in pdf format Supplementary material PreviousNextCite this article as: Grangeré K, Lefebvre S, Bacher C, Cugier P, Ménesguen A (2010) Modelling the spatial heterogeneity of ecological processes in an intertidal estuarine bay: dynamic interactions between bivalves and phytoplankton. Mar Ecol Prog Ser 415:141-158. https://doi.org/10.3354/meps08659Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 415. Online publication date: September 29, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.
Highlights
Processes of spatial heterogeneity have been shown to exert a crucial influence on ecosystem function (e.g. Dutilleul 1993, Legendre 1993, Borcard et al 2004).Both abiotic and biotic variables that govern the structuring of ecosystems display spatial patterns (Borcard et al 2004), so that living beings in nature are neither distributed uniformly nor completely at random (Legendre 1993)
The main biotic factor influencing the spatial pattern of benthic biomass is food availability (Fujii 2007, van der Wal et al 2008), and it is well known that abiotic processes play a key role in controlling the food supply to benthic filter feeders (Legendre et al 1997, Ysebaert et al 2003, Simpson et al 2007)
The present study was undertaken in order to identify the key processes that best explain the observed spatial heterogeneity in phytoplankton biomass and oyster growth
Summary
Processes of spatial heterogeneity have been shown to exert a crucial influence on ecosystem function (e.g. Dutilleul 1993, Legendre 1993, Borcard et al 2004).Both abiotic and biotic variables that govern the structuring of ecosystems display spatial patterns (Borcard et al 2004), so that living beings in nature are neither distributed uniformly nor completely at random (Legendre 1993). In areas with high benthic biomass, phytoplankton dynamics are strongly linked to benthic processes (Officer et al 1982, Herman et al 1999) In addition to these biotic processes, plankton are structured by abiotic processes such as currents, winds, or vertical stratification/mixing, which drive biological response mechanisms (Hayward & McGowan 1985, Mackas et al 1985, Ludovisi et al 2005) and cause the appearance of gradients or patchy structures (Legendre 1993). This is especially the case for continental shelf systems, where the spatial patterns of plankton are usually larger than in the open ocean (Mackas et al 1985). The study of spatial patterns is a crucial step to understanding ecosystem functioning (Borcard et al 2004)
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