Search results for "Fishe"

Glomales species associated with surface and deep rhizosphere of Faidherbia albida in Senegal

2000

Five arbuscular mycorrhizal (AM) fungal species were isolated and propagated from surface and deep rhizospheres of Faidherbia albida trees growing in two ecoclimatic zones of West Africa: the semi-arid Sahelian and the more humid Sudano-Guinean areas. Of these species, Glomus aggregatum, Glomus caledonium, and Glomus mosseae were trapped by F. albida roots when cultivated with either surface or deep soils. Glomus fasciculatum was found exclusively at the semi-arid Sahelian sites of Louga and Diokoul and Gigaspora margarita was isolated only from 16.5-m and 34-m-deep samples. Comparable glomalean fungal species richness was identified in deep (1.5–34 m) and surface (0.15 m) samples. The isol…

Multitrophic interactions in the rhizosphere Rhizosphere microbiology: at the interface of many disciplines and expertises.

2008

The rhizosphere – the soil compartment influenced by the root, including the root itself – is the most-active microbial habitat in soils. Indeed, the release by plant roots of a significant part of their photosynthates promotes microbial abundance and activities in the rhizosphere. This investment made by plants is paid back by microbial functions, which contribute to plant nutrition and protection against soil-borne diseases. Indeed, rhizosphere microorganisms play a major role in plant growth and health and, …

Mycorrhizae differentially influence the transfer of nitrogen among associated plants and their competitive relationships

2021

Abstract The formation of a common mycorrhizal network among roots of different plant species growing close to each other can influence plant community dynamics, regulating plant relationships through the differential transfer of nutrients from one plant to another. However, knowledge of the mechanisms that regulate this process is poor. Here we quantify the contribution of arbuscular mycorrhizae to the transfer of N among heterospecific plants growing adjacent to each other and examine whether the differential transfer of N within the plant community via mycorrhizae can alter competitive relationships among plant species. Plants of four species (wheat, pea, flax, and chicory) were grown in…

Einstein and Twentieth-Century Politics: ‘A Salutary Moral Influence’

2017

Bees increase oilseed rape yield under real field conditions

2018

prod 2018-210 EA GESTAD INRA; International audience; Oilseed rape (OSR, Brassica napus L.) is a common crop found in many European agricultural landscapes. It ispollinated by a wide variety of insects, but the reported contribution of pollinators to yield varies widely betweenstudies (from 0 to 50%). Moreover, such a contribution has seldom been estimated at the field scale in realfarming conditions. We analysed OSR yields in response to insect pollination; over four years, at two differentscales: farm fields and individual plants. We used both empirical and experimental approaches along a gradientof pollinator diversity and abundance. The empirical approach was based on farm surveys (151 …

Exploring the presence of pollutants at sea: Monitoring heavy metals and pesticides in loggerhead turtles (Caretta caretta) from the western Mediterr…

2017

Marine turtles are considered good sentinel species for environmental assessment because of their long lifespan, feeding ecology, habitat use and migratory nature. In the present study, we assessed presence of cadmium, lead and mercury, together with organic pollutants, both in fat and muscle tissue of 25 stranded loggerhead turtles (Caretta caretta) stranded along the Valencian Community coast (East Spain) (43.7±13.5cm). Mean concentrations of Cd, Pb and Hg were 0.04μg/g w.w., 0.09μg/g w.w. and 0.03μg/g w.w. in fat and 0.05μg/g, 0.08μg/g and 0.04μg/g in muscle, respectively. These measures indicate a relatively low mean heavy metal concentration, which may be explained by juvenile size and…

Otolith fingerprints reveals potential pollution exposure of newly settled juvenile Sparus aurata

2020

Abstract Coastal ecosystems are increasingly threatened by a wide range of human activities. Fish otolith chemistry, by creating a unique specific signature, can be used as a natural tag for determining life stage dispersal, spatial connectivity and population structure. In this study, we tested whether differences in otolith composition among juveniles of gilthead sea bream, Sparus aurata, could enable their proper allocation to polluted areas based on higher concentrations of elements related to contaminants. Otoliths were embedded, sectioned and analysed by LA-ICP-MS in line scan mode. Multivariate analysis confirmed clear separation between sites and elements. Samples from the site unde…

Detection of Allee effects in marine fishes: analytical biases generated by data availability and model selection

2017

The demographic Allee effect, or depensation, implies positive association between per capita population growth rate and population size at low abundances, thereby lowering growth ability of sparse populations. This can have far-reaching consequences on population recovery ability and colonization success. In the context of marine fishes, there is a widespread perception that Allee effects are rare or non-existent. However, studies that have failed to detect Allee effects in marine fishes have suffered from several fundamental methodological and data limitations. In the present study, we challenge the prevailing perception about the rarity of Allee effects by analysing nine populations of …

The effects of oil spills on marine fish: Implications of spatial variation in natural mortality.

2017

The effects of oil spills on marine biological systems are of great concern, especially in regions with high biological production of harvested resources such as in the Northeastern Atlantic. The scientific studies of the impact of oil spills on fish stocks tend to ignore that spatial patterns of natural mortality may influence the magnitude of the impact over time. Here, we first illustrate how spatial variation in natural mortality may affect the population impact by considering a thought experiment. Second, we consider an empirically based example of Northeast Arctic cod to extend the concept to a realistic setting. Finally, we present a scenario-based investigation of how the degree of …

Fine-scale population dynamics in a marine fish species inferred from dynamic state-space models

2017

1. Identifying the spatial scale of population structuring is critical for the conservation of natural populations and for drawing accurate ecological inferences. However, population studies often use spatially aggregated data to draw inferences about population trends and drivers, potentially masking ecologically relevant population sub‐structure and dynamics. 2. The goals of this study were to investigate how population dynamics models with and without spatial structure affect inferences on population trends and the identification of intrinsic drivers of population dynamics (e.g. density dependence). 3. Specifically, we developed dynamic, age‐structured, state‐space models to test differe…