Search results for "Dynamic"
showing 10 items of 12329 documents
Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave su…
2021
The authors acknowledge COST Action ES 1105 "CYANOCOST Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management" and COST Action Global Change Biology ES 1201 NETLAKE -Networking Lake Observatories in Europe" for contributing to this study through networking and knowledge sharing with European experts in the field. We acknowledge the members of the Global Lake Ecological Observatory Network (GLEON) for their collaborative spirit and enthusiasm that inspired the grassroots effort of the EMLS. E.M. was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation to Bas Ibelings and by supplementary funding from University of Geneva…
Cellulose ether emulsions as fat source in cocoa creams: Thermorheological properties (flow and viscoelasticity)
2019
Flow behaviour and viscoelastic properties at three different temperatures (20, 45 and 70 °C) of cocoa filling creams have been studied. These creams were composed of cocoa, starch, sugar, skimmed milk powder and non-digestible cellulose ether emulsions as fat source. Two types of methylcelluloses, MC, and two types of hydroxypropyl methylcelluloses, HPMC, with different chemical substitution degrees were employed. Results showed important differences in zero shear viscosity and shear thinning character at room temperature, due to the different internal structure revealed by the viscoelastic moduli spectra. Temperature sweeps of storage modulus showed different temperature gelation dependin…
Effects of a mobile disturbance pattern on dynamic patch networks and metapopulation persistence
2021
Abstract Motivation Certain early-succession habitats may emerge only at restricted locations following disturbance. Therefore, whether disturbances tend to occur at certain sites or not can significantly affect habitat availability and metapopulation persistence of early-successional habitat specialists. Available models that combine metapopulation and landscape processes do not address how to model mobile, spatially shifting disturbance intensities independent of factors of site suitability. We present a model that allows the study on how a mobile disturbance pattern, of either natural or anthropogenic origin, affects patch network and metapopulation dynamics in realistic, heterogeneous l…
Low temperature trumps high food availability to determine the distribution of intertidal mussels Perna perna in South Africa
2016
Explanations of species distributions often assume that the absence of a species is due to its inability to tolerate an environmental variable. Recent modelling techniques based on the dynamic energy budget (DEB) theory offer an effective way of identifying how interacting environmental parameters influence distributions through non-lethal effects on growth and development. The mussel Perna perna is an abundant ecosystem engineer around the coasts of Africa, South America and the Arabian peninsula, with an unexplained 1500 km lacuna in its distribution on the west coast of South Africa. We used a DEB approach to explain its distribution in southern Africa and test the hypothesis that this l…
High-resolution numerical modelling of the barotropic tides in the Gulf of Gabes, eastern Mediterranean Sea (Tunisia)
2017
International audience; A high-resolution 2D barotropic tidal model was developed for the Gulf of Gabes and used to characterise hydrodynamic processes and tidal dynamics. The model is based on the Regional Ocean Modelling System. It is forced at the open boundaries by the semidiurnal M2 and S2 astronomical components while meteorological forcing has been neglected. The model results show good agreement with observations confirming that it reproduces the gulf's main tidal characteristics reasonably well. In fact, the simulated semidiurnal tidal components M2 and S2 generate important sea level variations and coastal currents. Tidal propagation is directed to the gulf's western sector while …
Eight decades of sampling reveal a contemporary novel fish assemblage in coastal nursery habitats.
2015
In order to adequately monitor biodiversity trends through time and their responses to natural or anthropogenic impacts, researchers require long time series that are often unavailable. This general lack of datasets that are several decades or longer makes establishing a background or baseline of diversity metrics difficult - especially when attempting to understand species composition changes against a backdrop of climate and ecological variability. Here, we present an analysis of a community of juvenile nearshore fishes based on nearly 8 decades of highly standardized Norwegian survey records. Using multivariate statistical techniques, we: (i) characterize the change in taxonomic communit…
Trans-equatorial migration routes, staging sites and wintering areas of a High-Arctic avian predator: the Long-tailed Skua (Stercorarius longicaudus).
2013
The Long-tailed Skua, a small (,300 g) Arctic-breeding predator and seabird, is a functionally very important component of the Arctic vertebrate communities in summer, but little is known about its migration and winter distribution. We used lightlevel geolocators to track the annual movements of eight adult birds breeding in north-east Greenland (n = 3) and Svalbard (n = 5). All birds wintered in the Southern Hemisphere (mean arrival-departure dates on wintering grounds: 24 October-21 March): five along the south-west coast of Africa (0–40uS, 0–15uE), in the productive Benguela upwelling, and three further south (30–40uS, 0–50uE), in an area extending into the south-west Indian Ocean. Diffe…
The irreducible uncertainty of the demography–environment interaction in ecology
2002
The interpretation of ecological data has been greatly improved by bridging the gap between ecological and statistical models. The major challenge is to separate competing hypotheses concerning demography, or other ecological relationships, and environmental variability (noise). In this paper we demonstrate that this may be an arduous, if not impossible, task. It is the lack of adequate ecological theory, rather than statistical sophistication, which leads to this problem. A reconstruction of underlying ecological processes can only be done if we are certain of either the demographic or the noise model, which is something that can only be achieved by an improved theory of stochastic ecologi…
A modified niche model for generating food webs with stage‐structured consumers: The stabilizing effects of life‐history stages on complex food webs
2021
Abstract Almost all organisms grow in size during their lifetime and switch diets, trophic positions, and interacting partners as they grow. Such ontogenetic development introduces life‐history stages and flows of biomass between the stages through growth and reproduction. However, current research on complex food webs rarely considers life‐history stages. The few previously proposed methods do not take full advantage of the existing food web structural models that can produce realistic food web topologies.We extended the niche model developed by Williams and Martinez (Nature, 2000, 404, 180–183) to generate food webs that included trophic species with a life‐history stage structure. Our me…
Environmental change and disease dynamics: effects of intensive forest management on Puumala hantavirus infection in boreal bank vole populations.
2012
Intensive management of Fennoscandian forests has led to a mosaic of woodlands in different stages of maturity. The main rodent host of the zoonotic Puumala hantavirus (PUUV) is the bank vole (Myodes glareolus), a species that can be found in all woodlands and especially mature forests. We investigated the influence of forest age structure on PUUV infection dynamics in bank voles. Over four years, we trapped small mammals twice a year in a forest network of different succession stages in Northern Finland. Our study sites represented four forest age classes from young (4 to 30 years) to mature (over 100 years) forests. We show that PUUV-infected bank voles occurred commonly in all forest age…