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Bioécologie

La déforestation menace les oiseaux à grand bec et les graines de palmier au Brésil

27 Février 2016,

Publié par Bioécologie

Un article d'Emmanuel Perrin publié sur Maxisciences (8 juin 2013)

"Selon une nouvelle étude, la disparition des oiseaux à grand bec liée à la fragmentation des forêts tropicales brésiliennes a entrainé dans la région une diminution de la taille et de la vivacité des graines de palmier.

Nombreuses sont les conséquences de la déforestation. Pour les scientifiques, la prise de conscience des tenants et aboutissants d'une activité aussi dévastatrice est donc un véritable défi. Une nouvelle fois, une équipe internationale de chercheurs a mis en évidence une répercussion jusqu'à présent insoupçonnée. Selon leur nouvelle étude, la disparition des oiseaux à grands becs dans les forêts tropicales brésiliennes a entrainé au cours du dernier siècle une réduction notable des graines de palmiers.

Pour en arriver à une telle conclusion, les chercheurs ont récolté des graines sur des sites intacts de la forêt vierge brésilienne et les ont comparées avec celles des zones ayant servi dans les années 1800 aux exploitations de café et de Canne à Sucre. Au total, 9.000 graines provenant de 22 populations différentes d'Euterpe edulis ont été ramassées. Les résultats, publiés dans la revue Science (The birds and the seeds, Science, 31 mai 2013) mettent en évidence des graines nettement plus petites dans les zones de la forêt fragmentées par les plantations de sucre ou de café.

Selon les scientifiques, une telle conséquence serait directement liée à la disparition des oiseaux à grand bec et "disperseurs" de grosses graines, comme le toucan ou de grands cotingas. Ces animaux sont en effet incapables de nicher dans des territoires fragmentés par les plantations. Des analyses génétiques supplémentaires ont permis de déterminer le temps de réduction de la taille des graines de palmier après la perturbation initiale. Celui-ci ne serait que d'une centaine d'année.

Un changement aux lourdes conséquences

Ce bouleversement de l'écosystème peut avoir des effets désastreux. "Les petites graines sont plus vulnérables à la dessiccation et ne pourront (...)

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Un toucan toco (Ramphastos toco) - Photo de Lindolfo Souto (http://500px.com/LindolfoSouto)

Un toucan toco (Ramphastos toco) - Photo de Lindolfo Souto (http://500px.com/LindolfoSouto)

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)

Post-doctoral position

22 Février 2016,

Publié par Bioécologie

Post-doctoral position at the University of Lorraine (France)

Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), CNRS UMR 7360

Title: Predicting and understanding Rare Earth Element (REE) effects at the sediment-water interface

Context: Effective and sustainable use of strategic mineral resources is a high societal, scientific and economical priority. Yet, information on the interactions between REE and biota is often limited, especially for sediment-dwelling organisms that may be the most impacted by such activities.

In the absence of acid-mine drainage (AMD), cationic metals mobilized into the environment from mining activities (extraction and processing) actually tend to associate with suspended particulate matter (SPM) and accumulate into bed sediments. These phenomena reduce exposure of pelagic organisms to potentially harmful trace elements, but result in their corresponding accumulation in bottom sediments. Furthermore, even in the presence of AMD, the gradual neutralization of the acid effluents will eventually result in the deposition of metals to bed sediments via colloidal pumping, adsorption onto SPM and sedimentation. Understanding if and how mining of REE will result in adverse effects to organisms living inside bed sediments or at the sediment-water interface is therefore a highly relevant question for the all decision concerning present and foreseeable REE mining.

Objectives and work summary: In the current geopolitical and economical context, (re)opening of mining facilities for REE extraction is being explored in several countries. This project proposes to study if and how (re)opening of REE mines will alter the normal ecology of organisms living at the sediment- water interface. The proposed approach includes a field study at sites being considered for mining activities, in situ experiments with animal and vegetal model aquatic species and laboratory experiments. The overall objective of this post-doctoral position is to establish a solid knowledge of REE ecotoxicity to benthic organisms in order to ensure a sober management of natural resources.

The following specific objectives will constitute the core of the proposed work:

  • Establish baseline environmental conditions and trophic transfer at sites where rocks naturally rich in REE occur. The Labex consortium has already identified suitable study areas (perspective mining sites with different mineralogies of REE containing rocks) in Canada. Water, sediments and representative benthic organisms will be collected and analyzed for their REE content. Knowledge of baseline environmental conditions before anthropogenic activities is invaluable to manage mining activities during and after exploitation.
  • Determine the safe concentrations of REE mixtures to representative benthic organisms. Field sediments collected at perspective mining sites will be spiked with REE mixtures representative of the corresponding ore composition. A battery of model organisms will be exposed to the spiked sediments and monitored for relevant endpoints. Detailed characterization of exposure conditions will be carried out throughout the duration of the organisms’ exposure to contaminated sediments.
  • Explore possible early-warning endpoints of REE effects. Current knowledge surmises that a contaminant causes adverse effects when its metabolically active concentration inside an organism exceeds a certain threshold. Sub cellular distribution of REE will be studied in an attempt to establish such links. Alternatively, the use of behavioral responses or cellular biomarkers will be explored as early signals for effects at the individual and population levels.

Student profile: The candidate must be a highly-motivated and self-directed person with a recent university doctoral degree (or equivalent) in ecotoxicology or environmental toxicology. A solid background in biology, ecotoxicology, stress ecology and a strong interest for both experimental and in situ studies are required. He or she may demonstrate fundamental knowledge and / or quantitative analytical techniques and document acquired knowledge in these topics. Basic level in freshwater physico-chemistry will be also appreciated. The candidate will need to be fluency in English and in French (or willingness to learn French).

Funding: This post-doctoral position will be funded by the LabEx RESSOURCES21 which was selected by the French Ministry of Research and Education in the framework of the "Laboratoires d'Excellence" initiative. RESSOURCES21 proposes an integrated scientific and educational approach to the understanding, exploitation and environmental management of strategic metal resources for the 21th century. This post-doctoral fellowship is funded for one year with the possibility of a further extension for an additional year.

Host institution: LIEC (Laboratoire Interdisciplinaire des Environnements Continentaux), Metz, France. http://www.liec.univ-lorraine.fr

Salary: 45 k€ annual gross salary

Entry into service: May 2016

Applicants should send via email Curriculum Vitae and the names and email addresses of two references to:

Davide A.L. Vignati (david-anselmo.vignati@univ-lorraine.fr) & Laure Giamberini (laure.giamberini@univ-lorraine.fr)

Application deadline: March 15th 2016

Lake Superior Ice Stacking

21 Février 2016,

Publié par Bioécologie

Cette scène filmée par Dawn LaPointe montre une fine couche de glace à la surface du Lac Supérieur en Amérique du Nord venir se briser sur le rivage de Duluth dans le Minnesota.

Le grand voyage de Charles Darwin - Les origines de la théorie de l’évolution

17 Février 2016,

Publié par Bioécologie

En 1831, Charles Darwin a 22 ans. Naturaliste fraîchement diplômé de Cambridge, il se prépare à devenir pasteur, selon le voeu de son père. Mais une perspective autrement plus tentante s’offre soudain : participer, en tant que scientifique, à l’expédi­tion du Beagle, qui part cartographier l’Améri­que du Sud sous les ordres du jeune capitaine Fitzroy.

Un fabuleux voyage qui, au total, durera cinq ans, de la première étape (le cap Vert, où il découvre déjà plus de cent espèces différen­tes) aux îles Cocos, un atoll du Pacifique, via le Brésil, la Terre de Feu, les Galápagos, le Chili, l’Australie… Partout, Darwin explore, collecte, analyse, expédiant au fur et à mesure en Angleterre des milliers de spécimens, végé­taux et animaux, qui figurent aujourd’hui parmi les trésors scientifiques de la Couronne.

32nd International Conference on Environmental Geochemistry and Health

4 Février 2016,

Publié par Bioécologie

32nd International Conference on Environmental Geochemistry and Health
32nd International Conference on Environmental Geochemistry and Health

Organized by the Laboratoire G-Time of ULB (Laboratoire Geochemistry - Tracing by Isotopes, Elements and Minerals) this annual conference of the Society for Environmental Geochemistry and Health provides a forum for international scientists, consultants, regulatory authorities and other practitioners (public health / environmental health) with an interest in the links between environment and health and working in the broad area of environmental geochemistry.

Abstract submission deadline: March 2nd, 2016

For the 32nd SEGH there are three core themes (Dust and Aerosol; Isotopes and Speciation; Geochemistry and Health) and three special sessions (SpatioTemporal Trends of Metal Contaminants in the Atmosphere; Nanoparticles in the Environment: Fate and Effects; Geochemistry and Biomedical Issues).

Bioecologie put a spotlight on this Special Session:

Special Session 2 – Nanoparticles in the Environment: Fate and Effects

Special Session chaired by Camille Larue1,2, Laure Giamberini3,Eric Pinelli1,2, Laury Gauthier1,2

1 Université de Toulouse; INP, UPS; EcoLab (Laboratoire d’Ecologie Fonctionnelle et Environnement); ENSAT, France

2 CNRS; EcoLab; France

3Université de Lorraine, LIEC (Laboratoire Interdisciplinaire des Environnements Continentaux), France

Nanoparticles, both from natural and anthropogenic origins, have always existed in our environment. They are present in every compartments, from ultrafine atmospheric particles to nanoparticles present in the colloidal fraction of soils and water. Recent decades have seen the emergence of manufactured nanoparticles (NPs) with new properties used in various applications (medicine, electronics, computers, automotive industry, and in more than 1800 consumer products including food) raising concerns about their fate in the environment due to enhanced surface reactivity. If no strict regulations are currently effective concerning NPs, several OECD or FDA recommendations are already available for industry and toxicological testing. It has also been underlined the necessity to develop knowledge in analysis and characterization of NPs in physical and biological matrixes, and their eco(toxicity). This has led to a number of questions as their speciation, their interaction with other contaminants or their effects associated with human health and environmental risks. This session aims at being a discussion forum centered on: (i) NP physico-chemical characterization, (ii) their interactions with living organisms and (iii) their potential environmental and health issues. Young researchers are encouraged to present their work.


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