The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
C H R Heip - One of the best experts on this subject based on the ideXlab platform.
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benthic community structure and sediment processes on an intertidal flat results from the ecoflat project
Continental Shelf Research, 2001Co-Authors: P M J Herman, Jack J Middelburg, C H R HeipAbstract:Interactions between physical and biological processes in intertidal sediments have been the focus of studies in the framework of the ECOFLAT project. Process studies were focused on the Molenplaat, a 1.5 km(2) intertidal flat in the Westerschelde estuary, The Netherlands. Distinct spatial patterns in the biological community on the flat were found and related to patterns in bottom shear stress as derived from a hydrodynamic model. Based on these survey results five stations were selected with contrasting sediment composition and benthic communities. Long-term net sedimentation of mainly sand was deduced from radionuclide profiles. Sedimentation of mud on the surface of part of the intertidal flat was shown to be a seasonally cyclic process, with a magnitude sufficient to significantly affect the mud balance of the estuary. Measurements of erodability as a function of tidal current showed a biological control on this variable. Benthic microalgae stabilise the sediment surface, whereas the benthic macrofauna has a destabilising effect. Food web studies show that the contrasting biological communities (microbenthos, meiobenthos, Macrobenthos) at muddy and sandy sites have substantial differences in the quantitative aspects of their food web. Turnover of microalgae is much lower at muddy than at sandy sites, and this is mostly related to a lower grazing pressure. It is hypothesised that high mud content decreases the availability of benthic microalgae to grazers. We demonstrate a positive feedback between benthic microalgae and mud sedimentation which may lead to the existence of different stable states. This may explain the existence of relatively sharp boundaries and strong community contrasts in the presence of weak and smooth environmental gradients. [KEYWORDS: Tidal flat; westerschelde-estuary; ecosystem engineers arenicola -marina; microphytobenthos; netherlands; stability phytoplankton; Macrobenthos; organisms]
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ecology of estuarine Macrobenthos
Advances in Ecological Research, 1999Co-Authors: P M J Herman, Jack J Middelburg, J Van De Koppel, C H R HeipAbstract:Macrobenthos is an important component of estuarine ecosystems. Based on a cross-system comparison, we show that estuarine Macrobenthos may directly process a significant portion of the system-wide primary production, and that estuarine macrobenthic biomass may be predicted from primary production data. At large scales, food may be the prime limiting factor for benthic biomass. Depending on the characteristics of the system, grazing by benthic suspension feeders may be the most important factor determining system dynamics. The detailed spatial patterns and dynamics resulting from feeding interactions are discussed separately for suspension feeders and deposit feeders. The theory on local seston depletion and its consequences for spatial distribution of suspension feeders is compared critically with observed patterns of spatial distribution. It is concluded that additional non-linear interactions between biomass of the benthos and water currents must exist to explain the observed patterns. The relation between organic matter deposition fluxes and benthic community structure is discussed in the framework of the classical Pearson-Rosenberg paradigm. The importance of organic matter quality, in addition to quantity, is stressed. A simple model framework to investigate the relation between community structure and quantity of organic flux is proposed. Internal dynamics of benthic food webs are characterized by a high degree of omnivory (feeding on different trophic levels). This feature is contrasted with published data on food webs in other systems. It is hypothesized that the high quality of marine detritus (compared with terrestrial detritus) is the prime factor explaining the differences. Since theoretical studies suggest that omnivory destabilizes food webs, a number of stabilizing mechanisms in benthic food webs are discussed. Problems and mechanisms that could be explored fruitfully in theoretical studies and field comparisons are identified.
P M J Herman - One of the best experts on this subject based on the ideXlab platform.
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distribution and dynamics of intertidal Macrobenthos predicted from remote sensing response to microphytobenthos and environment
Marine Ecology Progress Series, 2008Co-Authors: P M J Herman, R M Forster, T Ysebaert, Francesca Rossi, E Knaeps, Y Plancke, S J IdesAbstract:We investigated which variables, including environmental variables and food availabil- ity, could predict the spatial distribution and dynamics of benthic macrofauna on an intertidal flat. A time series of Macrobenthos and sediment grain size samples was complemented by time series of microphytobenthos and saltmarsh vegetation biomass and sediment grain size from airborne hyper- spectral remote sensing, and elevation from laser altimetry. Response models were constructed to predict biomass and species richness of Macrobenthos as a function of the environmental variables. Total biomass and species richness was best predicted by a combination of microphytobenthos biomass and sediment characteristics as explanatory variables. Deep deposit feeders and surface deposit feeders also responded best to a combination of variables, with deep deposit feeders responding more strongly to sediment grain size and surface deposit feeders responding more strongly to microphytobenthos biomass. The environmental conditions to reach maximum biomass differed for each Macrobenthos species. Application of the response models to the remote sensing- derived maps of the environmental variables enabled significant predictions of the spatial distribu- tion of Macrobenthos biomass, demonstrating the differences in distribution of the Macrobenthos spe- cies. The models also revealed the sensitivity of the macrobenthic community to environmental change. In situ and remote sensing data demonstrated a significant fining of the sediment and a (tem- poral) increase in average microphytobenthos biomass. Field observations also showed a significant increase in species richness and changes in the relative abundance of species, with a decrease in Bathyporeia pilosa, and an increase in Nereis diversicolor, Pygospio elegans and Heteromastus filiformis. Such changes in Macrobenthos biomass and species richness were indeed predicted from the response models. The study demonstrates that the synoptic remote sensing techniques combined with field sampling allow efficient ecological mapping and monitoring.
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benthic community structure and sediment processes on an intertidal flat results from the ecoflat project
Continental Shelf Research, 2001Co-Authors: P M J Herman, Jack J Middelburg, C H R HeipAbstract:Interactions between physical and biological processes in intertidal sediments have been the focus of studies in the framework of the ECOFLAT project. Process studies were focused on the Molenplaat, a 1.5 km(2) intertidal flat in the Westerschelde estuary, The Netherlands. Distinct spatial patterns in the biological community on the flat were found and related to patterns in bottom shear stress as derived from a hydrodynamic model. Based on these survey results five stations were selected with contrasting sediment composition and benthic communities. Long-term net sedimentation of mainly sand was deduced from radionuclide profiles. Sedimentation of mud on the surface of part of the intertidal flat was shown to be a seasonally cyclic process, with a magnitude sufficient to significantly affect the mud balance of the estuary. Measurements of erodability as a function of tidal current showed a biological control on this variable. Benthic microalgae stabilise the sediment surface, whereas the benthic macrofauna has a destabilising effect. Food web studies show that the contrasting biological communities (microbenthos, meiobenthos, Macrobenthos) at muddy and sandy sites have substantial differences in the quantitative aspects of their food web. Turnover of microalgae is much lower at muddy than at sandy sites, and this is mostly related to a lower grazing pressure. It is hypothesised that high mud content decreases the availability of benthic microalgae to grazers. We demonstrate a positive feedback between benthic microalgae and mud sedimentation which may lead to the existence of different stable states. This may explain the existence of relatively sharp boundaries and strong community contrasts in the presence of weak and smooth environmental gradients. [KEYWORDS: Tidal flat; westerschelde-estuary; ecosystem engineers arenicola -marina; microphytobenthos; netherlands; stability phytoplankton; Macrobenthos; organisms]
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ecology of estuarine Macrobenthos
Advances in Ecological Research, 1999Co-Authors: P M J Herman, Jack J Middelburg, J Van De Koppel, C H R HeipAbstract:Macrobenthos is an important component of estuarine ecosystems. Based on a cross-system comparison, we show that estuarine Macrobenthos may directly process a significant portion of the system-wide primary production, and that estuarine macrobenthic biomass may be predicted from primary production data. At large scales, food may be the prime limiting factor for benthic biomass. Depending on the characteristics of the system, grazing by benthic suspension feeders may be the most important factor determining system dynamics. The detailed spatial patterns and dynamics resulting from feeding interactions are discussed separately for suspension feeders and deposit feeders. The theory on local seston depletion and its consequences for spatial distribution of suspension feeders is compared critically with observed patterns of spatial distribution. It is concluded that additional non-linear interactions between biomass of the benthos and water currents must exist to explain the observed patterns. The relation between organic matter deposition fluxes and benthic community structure is discussed in the framework of the classical Pearson-Rosenberg paradigm. The importance of organic matter quality, in addition to quantity, is stressed. A simple model framework to investigate the relation between community structure and quantity of organic flux is proposed. Internal dynamics of benthic food webs are characterized by a high degree of omnivory (feeding on different trophic levels). This feature is contrasted with published data on food webs in other systems. It is hypothesized that the high quality of marine detritus (compared with terrestrial detritus) is the prime factor explaining the differences. Since theoretical studies suggest that omnivory destabilizes food webs, a number of stabilizing mechanisms in benthic food webs are discussed. Problems and mechanisms that could be explored fruitfully in theoretical studies and field comparisons are identified.
Hongxia Zhou - One of the best experts on this subject based on the ideXlab platform.
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impacts of an alien species spartina alterniflora on the Macrobenthos community of jiangsu coastal inter tidal ecosystem
Ecological Engineering, 2009Co-Authors: Hongxia ZhouAbstract:Abstract Spartina alterniflora , a species vegetating on inter-tidal flats that was introduced from the eastern coast of United States, has become a hot topic, focusing on its invasion within local species in the coastal zone of China. Impacts of S. alterniflora on the inter-tidal Macrobenthos community in the Jiangsu coastland are addressed by comparing the Macrobenthos characteristics in a mudflat and in a four-year-old Spartina salt marsh that had earlier been a mudflat. During the period October 2002–July 2003, we studied the distribution pattern and diversity of Macrobenthos, and discussed their correlation with environmental factors caused by Spartina vegetation. The results showed that a total of 43 Macrobenthos species were found, mainly consisting of Mollusca, Crustacea, and Annelida. Ten Macrobenthos species were found in the Spartina salt marsh, and 36 species were found in the mudflat. Life forms and functional groups of Macrobenthos in the Spartina salt marsh were obviously distrinct from that of the mudflat. The study showed that Macrobenthos diversity in the Spartina salt marsh decreased, and the community structure altered obviously, whereas the biomass showed no differences in different seasons. Statistical analysis demonstrated that seasonal change of Macrobenthos diversity in the Spartina salt marsh negatively related to content of sediment organic matter, total N, bulk density, height and biomass of Spartina vegetation, and positively related to the density of Spartina . All these differences suggested the obvious effects of the Spartina vegetation on the Jiangsu inter-tidal benthic macroinvertebrate ecology. Furthermore, the investigation also showed that the niche of the native Macrobenthos living in the mudflat has been transferred down, seaward, due to the invasion of Spartina in our study site.
Hyunjoo Oh - One of the best experts on this subject based on the ideXlab platform.
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Macrobenthos habitat mapping in a tidal flat using remotely sensed data and a gis based probabilistic model
Marine Pollution Bulletin, 2011Co-Authors: Jong-kuk Choi, Hyunjoo OhAbstract:This paper proposes and tests a method of producing macrofauna habitat potential maps based on a weights-of-evidence model (a probabilistic approach) for the Hwangdo tidal flat, Korea. Samples of Macrobenthos were collected during field work, and we considered five mollusca species for habitat mapping. A weights-of-evidence model was used to calculate the relative weights of 10 control factors that affect the Macrobenthos habitat. The control factors were compiled as a spatial database from remotely sensed data combined with GIS analysis. The relative weight of each factor was integrated as a species potential index (SPI), which produced habitat potential maps. The maps were compared with the surveyed habitat locations, revealing a strong correlation between the potential maps and species locations. The combination of a GIS-based weights-of-evidence model and remote sensing techniques is an effective method in determining areas of Macrobenthos habitat potential in a tidal flat setting.
Takashi Sakamaki - One of the best experts on this subject based on the ideXlab platform.
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Watershed Effects on Chemical Properties of Sediment and Primary Consumption in Estuarine Tidal Flats: Importance of Watershed Size and Food Selectivity by Macrobenthos
Ecosystems, 2010Co-Authors: Takashi Sakamaki, Jennifer Y. T. Shum, John S. RichardsonAbstract:Particulate organic matter transported from rivers to estuaries (POM_R) varies quantitatively and qualitatively across estuaries; however, a lack of comparative studies poses a challenge in general understanding of responses of estuarine food webs to POM_R input. We studied 20 estuarine tidal flats of the Pacific Northwest coast of North America, with watershed areas ranging from 7 to 8000 km^2. We used carbon-stable isotope (δ^13C) to test the hypothesis that the nutritional contribution of POM_R to Macrobenthos is proportional to relative abundances of POM_R in tidal flat sediments. The predominant origin of total POM (TPOM) in tidal flat sediments generally shifted from marine-origin POM (POM_M) to POM_R as watershed area increased; however, terrestrial-origin POM_R with high C/N predominated sediment TPOM even in estuaries with small watershed areas. Some Macrobenthos species assimilated POM sources in proportion to sediment TPOM composition, and incorporated POM_R in POM_R-predominant sediments. These species were considered to have low food selectivity; however, the relative nutritional contribution of POM_R to these Macrobenthos was still lower than the fraction of POM_R in sediment TPOM. Other species disproportionately utilized POM_M and/or benthic microalgae regardless of the relative abundance of POM_R, indicating their high food selectivity. The species-specific, low- or high-food selectivity was likely linked with deposit-feeding and filter-feeding, respectively. Hence, our hypothesis was supported conditionally. Our findings indicate that watershed area, relative abundance of POM_R in an estuary, and food selectivity of estuarine species are key factors controlling the tightness of linkage between watersheds and estuarine food webs.
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Is sediment mud content a significant predictor of Macrobenthos abundance in low-mud-content tidal flats?
Marine and Freshwater Research, 2009Co-Authors: Takashi Sakamaki, Osamu NishimuraAbstract:Sediment mud content is a significant predictor of Macrobenthos abundance in marine soft-bottom habitats. However, the mechanisms behind the non-linearity generally shown in mud–Macrobenthos relationships have not been examined. The present study analysed spatial distributions of sediment properties and Macrobenthos in a tidal flat system of the north-east coast of Japan and tested the hypothesis: the non-linearity of mud–Macrobenthos relationship corresponds to changes in bed elevation variability and sediment cohesiveness. For two Macrobenthos species studied, Nuttallia olivacea (Bivalvia) and Hediste spp. (Polychaeta), the relationships between mud content (
