Overblog Suivre ce blog
Administration Créer mon blog

Articles avec #chercheurs - projets de recherche...

The aquatic-terrestrial model ecosystem – a possibility to integrate riparian food webs in stream mesocosm testing

27 Février 2016,

Publié par JMB

In this post, Matthias Wieczorek informs about their recent paper on the use of an aquatic-terrestrial model ecosystem to study cross-ecosystem effects of contaminants.

The scientific background

Emerging aquatic insects provide an important food source for predatory species in riparian food webs. If these aquatic insects are exposed to contaminants during their aquatic life stage, they may transport contaminants to riparian ecosystems during their emergence. Therefore, riparian food webs may be at risk from either an aquatic-terrestrial transfer of contaminants or from contaminant-driven reductions of emerging aquatic biomass. The objective of the present study was to develop an aquatic-terrestrial model ecosystem enabling the possibility to investigate such cross-ecosystem effects on a mesocosm scale under controlled conditions.

Read more here

The stream mesocosm facility at the Campus Landau (photo by M. Wieczorek)

The stream mesocosm facility at the Campus Landau (photo by M. Wieczorek)

Neurodevelopmental Disorders and Prenatal Residential Proximity to Agricultural Pesticides: The CHARGE Study

3 Février 2016,

Publié par Bioécologie

By Janie F. Shelton, Estella M. Geraghty, Daniel J. Tancredi, Lora D. Delwiche, Rebecca J. Schmidt, Beate Ritz, Robin L. Hansen, and Irva Hertz-Picciotto. June 2014.

  • Background: Gestational exposure to several common agricultural pesticides can induce developmental neurotoxicity in humans, and has been associated with developmental delay and autism.

    Objectives: We evaluated whether residential proximity to agricultural pesticides during pregnancy is associated with autism spectrum disorders (ASD) or developmental delay (DD) in the Childhood Autism Risks from Genetics and Environment (CHARGE) study.

    Methods: The CHARGE study is a population-based case–control study of ASD, DD, and typical development. For 970 participants, commercial pesticide application data from the California Pesticide Use Report (1997–2008) were linked to the addresses during pregnancy. Pounds of active ingredient applied for organophophates, organochlorines, pyrethroids, and carbamates were aggregated within 1.25-km, 1.5-km, and 1.75-km buffer distances from the home. Multinomial logistic regression was used to estimate the odds ratio (OR) of exposure comparing confirmed cases of ASD (n = 486) or DD (n = 168) with typically developing referents (n = 316).

    Results: Approximately one-third of CHARGE study mothers lived, during pregnancy, within 1.5 km (just under 1 mile) of an agricultural pesticide application. Proximity to organophosphates at some point during gestation was associated with a 60% increased risk for ASD, higher for third-trimester exposures (OR = 2.0; 95% CI: 1.1, 3.6), and second-trimester chlorpyrifos applications (OR = 3.3; 95% CI: 1.5, 7.4). Children of mothers residing near pyrethroid insecticide applications just before conception or during third trimester were at greater risk for both ASD and DD, with ORs ranging from 1.7 to 2.3. Risk for DD was increased in those near carbamate applications, but no specific vulnerable period was identified.

    Conclusions: This study of ASD strengthens the evidence linking neurodevelopmental disorders with gestational pesticide exposures, particularly organophosphates, and provides novel results of ASD and DD associations with, respectively, pyrethroids and carbamates.

More here

Why do some fish thrive in oil-polluted water?

3 Février 2016,

Publié par Bioécologie

Scientists thought guppies in Northern Trinidad could be a rare example of adaptation to crude oil pollution. But they found something else.

By Melody Enguix (26 JAN 2016):

When scientists from McGill University learned that some fish were proliferating in rivers and ponds polluted by oil extraction in Southern Trinidad, it caught their attention. They thought they had found a rare example of a species able to adapt to crude oil pollution.

At a time when humans are imposing an unprecedented burden on the world's ecosystems, studying how organisms can tolerate pollutants is crucial to understanding the impact of human activities – and to helping to mitigate it in the future.

Led by Dr. Gregor Rolshausen, then a postdoctoral researcher at McGill working with Prof. Andrew Hendry, the team went to study the guppy fish living in polluted areas, comparing their morphology and genetic makeup to those of similar guppies from non-polluted parts of Trinidad.

More here

Freshwater Information Platform

28 Septembre 2015,

Publié par Bioécologie

Major European research institutes have joined forces to enable and maintain the Freshwater Information Platform, a new community information resource.

Numerous EU funded projects addressing freshwater ecology and water management have generated websites, tools, databases and other products, which are intended for long-term use. However, many of them are not maintained after the project has ended and, moreover, they are dispersed across several project websites. For freshwater researchers and other users, it is challenging to gain an overview of projects and their products. The EU funded project BioFresh was the first to establish a platform — the Global Freshwater Biodiversity Information Platform — bringing together information and data on freshwater biodiversity in a clearly arranged and easily explorable way.

Irrationality in mate choice revealed by túngara frogs

7 Septembre 2015,

Publié par Bioécologie

Lea, A.M. and Ryan, M.J. 2015. Science, Vol. 349 no. 6251 pp. 964-966, DOI: 10.1126/science.aab2012

Mate choice models derive from traditional microeconomic decision theory and assume that individuals maximize their Darwinian fitness by making economically rational decisions. Rational choices exhibit regularity, whereby the relative strength of preferences between options remains stable when additional options are presented. We tested female frogs with three simulated males who differed in relative call attractiveness and call rate. In binary choice tests, females’ preferences favored stimulus caller B over caller A; however, with the addition of an inferior “decoy” C, females reversed their preferences and chose A over B. These results show that the relative valuation of mates is not independent of inferior alternatives in the choice set and therefore cannot be explained with the rational choice models currently used in sexual selection theory.

Read the full text