Duration: 24 months
Start: Spring – Summer 2025
Research objectives and hypotheses:
This post-doctorate is part of the ANR (French National Research Agency) STRANGE project (2023-2027) on the ecosystem services provided by aquatic insects in adjacent terrestrial environments. While the STRANGE project focuses on permanent aquatic environments, the aim of this post-doctorate is to quantify the biomass of aquatic insects (notably Diptera) emerging from temporary aquatic environments (ditches, flooded areas, wetlands, flooded grasslands, etc.) in order to model their fluxes in agricultural landscapes and estimate the associated ecosystem services (depollution by N and P export, fertilisation, support for food webs and pollination). To do this, it is necessary to identify all the temporary sources of aquatic insect emergence (in time and space), their diversity (floodable areas, ditches, etc.), their contribution to insect production and their hydrological functioning over time (i.e., seasons). The characterisation of these temporary aquatic areas will make it possible to quantify the biomass of insects produced throughout seasonal ecological monitoring and to model the associated flows. The main hypothesis is based on the fact that, compared with permanent habitats, temporary aquatic habitats represent an area where aquatic insect biomass production is currently largely underestimated. The second hypothesis is that the type of water supply to these environments (flooding or groundwater upwelling) will have a major impact on the temporal dynamics and therefore the production of biomass, the nature of the species that colonise them and therefore the ecosystem services provided, particularly in terms of nutrient flows (depollution, fertilisation).
This project has three innovative scientific aspects:
(1) The characterisation of temporary aquatic areas using new monitoring tools (i.e., UAV). The development of methods for systematic, large-scale mapping of submerged areas and their temporal fluctuations would constitute a major advance in the perception and quantification of the aquatic environment within our landscapes (often considered to be stable).
(2) The quantification of the biomass and emerging diversity of these temporary aquatic environments, mainly Diptera, which to date have never been quantified on a landscape scale. This is a scientific front at the interface between terrestrial ecology and aquatic ecology.
(3) The estimation of ecosystem services associated with aquatic insect fluxes. While very recent research has made it possible to model aquatic insect fluxes in a landscape on the basis of permanent aquatic environments, supplementing these tools with data relating to temporary aquatic environments would provide a much more exhaustive view of the impact of aquatic productivity on terrestrial environments.
Objectives and methodologies
Identification of temporary aquatic zones in space and time (Year 1).
The first objective will consist of characterising and quantifying the spatial and temporal evolution (i.e. seasonal fluctuations) of temporary aquatic zones in monitoring sites (i.e., Zones Ateliers Armorique and Brest-Iroise). The study areas are part of an interdisciplinary research network on socio-ecosystems and the environment in relation to societal issues approved by the CNRS (“Zone Atelier”). These long-term Socio-Ecological Research observatories provide a large amount of complementary environmental data.
The spatio-temporal characterisation and quantification of temporary water areas will be carried out using image analysis and photo-interpretation obtained by UAV overflights coupled with field surveys.
Characterisation of Insect biomass an diversity (year 1).
The second objective consists of quantifying biomass production and characterising the diversity of aquatic insects emerging in temporary environments in winter and early spring (flooded areas) through field monitoring. In temporary aquatic environments, emerging aquatic insects mainly belong to Diptera. To collect the insects, emergence traps will be set up in flooded meadows, ditches and wetlands during the flooding period. The insects will be identified and quantified in the laboratory, using the morphology and/or molecular tools.
Spatialisation of results (year 2).
The data obtained in objectives 1 and 2 will be integrated into flux models already developed within the laboratory and scientifically validated (Gerber et al. 2023).
Three stages will be necessary to produce these models:
1- Update the flux models developed for Ephemeroptera, Plecoptera and Trichoptera using Diptera data already collected as part of the ANR STRANGE project on the permanent streams.
2- Calibrate the model to integrate information relating to temporary aquatic environments (e.g. their surface areas, locations and hydrological functioning).
3- Weight the model by the biomass produced.
Host team
The person recruited will be affiliated with UMR CNRS 6553 ECOBIO (https://ecobio.univ-rennes.fr/en/). The research unit ECOBIO covers all areas of ecology: evolutionary ecology, behavioural ecology, community ecology, functional ecology and landscape ecology. The person recruited will benefit from the support of the technical platforms PEM (for molecular analyses), Ecolex (for support in field protocols and an optical center for the identification) and the D2T platform for the analysis of images obtained by drone. The person recruited will also be assisted by an engineer to carry out the technical parts of the project concerning the GIS analyses relating to the spatial modelling of the results.
Profile required
The candidate must have a PhD in terrestrial and/or aquatic ecology. Since, aquatic insect assemblages in temporary aquatic environment are mainly constitute by Diptera, a minimal experience on identification and/or ecology of Diptera would be greatly appreciated. Insects will be identified in the laboratory (on the basis of morphological criteria) and/or using molecular tools (barcoding and/or metabarcoding). However, experience in using molecular tools is not necessary, as training courses can be provided in our laboratory.
The candidate must have knowledge of data processing and an interest in basic and applied research. An aptitude for fieldwork, laboratory work and data processing is essential, as are good English writing skills.
The funding is intended for a post-doc who has spent at least 18 months outside France between May 1, 2021 and the start of the project.
Financial resources
The salary will be covered by the Bienvenüe program (https://msca-bienvenue.bretagne.bzh/). The BIENVENÜE funding covers are (1) a 24-month fellowship of a gross salary of 4 510€/month and (b) a full social security coverage according to French standards: family allowance, parental and sick leave, 25 vacation days per year minimum, transport contribution, pension contribution, unenmployment benefits.
The functional resources are associated with the STRANGE project (Ecosystem Services provided by sTReams to AdjaceNt aGricultural tErrestrial ecosystems; ANR funding, 2023-2027). This project brings together 10 French research units. It aims to assess the ecosystem services provided by aquatic ecosystems to adjacent agricultural environments via winged insects (crop fertilization, pollination, pest control services).
Supervision and application
The new recruit will be supervised by Christophe Piscart (Director of Research) at the CNRS, Benjamin Bergerot (Associate Professor) and Stéphane Derocles (Assistant Professor) at the University of Rennes.
To apply, please send a CV and covering letter to the supervisors (benjamin.bergerot@univ-rennes.fr, christophe.piscart@univ-rennes.fr and stephane.derocles@univ-rennes.fr
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