Thesis PHYCLIMED Past and future trajectories of MEDiterranean lagoons under CLIMate change : a[...]

Title

Thesis PHYCLIMED Past and future trajectories of MEDiterranean lagoons under CLIMate change : an integrated approach to hydrology and PHYtoplankton M/F - Sète - CDD

Position Summary

Deadline for applications: 7th of May, 2026

Ifremer's Occitanie Environment and Resources Laboratory (LEROC) is one of the nine laboratories that make up the COAST unit (Observation and Ecology of Coastal Ecosystem Restoration). It contributes its scientific and technical expertise on the quality of the marine ecosystem in the western Mediterranean.

LEROC is part of the MARBEC research unit (Marine Biodiversity, Exploitation and Conservation), whose four main sponsoring bodies are the IRD, Ifremer, the University of Montpellier and the CNRS. MARBEC is one of the largest laboratories working on marine biodiversity and its uses in France, with 285 staff members, including 96 researchers and senior lecturers.

Topic

Mediterranean lagoons are hotspots for climate change (CC) and are particularly vulnerable to it. These complex environments provide numerous ecosystem services, particularly in terms of food supply, such as shellfish farming and fishing. The combined effects of CC and oligotrophisation on phytoplankton are poorly understood, despite the fact that a decline in nutrient inputs has been observed in French Mediterranean lagoons over recent decades. Based on time series of lagoon, hydroclimatic and catchment evolution data, analysed retrospectively and with projections to 2050, this thesis aims to determine: 1) the influence of local climates and hydromorphology on lagoon functioning, 2) which phytoplankton taxa serve as indicators of CC, 3) which types of lagoons are more resilient. An interdisciplinary approach will be adopted, considering climate-watershed-lagoon systems. The thesis will provide relevant knowledge for assessing the impacts of CC on lagoons and anticipating future changes, by identifying scenarios according to sub-regions and lagoon types.

Responsibilities

The study will cover 16 lagoons in the regions along the French Mediterranean coast (Occitanie, PACA and Corsica) that are representative of the diversity of these ecosystems.

PHYCLIMED will use statistical analysis and artificial intelligence (AI) techniques to conduct a cross-analysis of time series characterising Mediterranean lagoon hydrosystems (climate/catchment/lagoon) over the period :

• climate data from the three Mediterranean regions;
• hydrological and hydromorphological data characterising the lagoons and their catchment areas;
• hydrological and phytoplankton data from 16 Mediterranean lagoons (DCE, REPHY/PHYTOBS).

The thesis project is structured around three main scientific questions:

Axis 1. Causal relationships between local climate, catchment hydrology and lagoon functioning

• identify the climatic (e.g. wind, rainfall, temperature, evapotranspiration) and hydrological variables characterising lagoon catchments (e.g. flow rates, soil moisture index, hydrological connectivity);
• consolidate lagoon hydromorphological groups by integrating the key variables characterising their local climate and catchment;
• analyse trends and shifts in lagoon variables (temperature, salinity, oxygen, nutrients, phytoplankton) by hydromorphological group.

Axis 2. Phytoplankton taxa as indicators of climate change

• conduct a more detailed retrospective analysis of the summer abundances of picocyanobacteria across all lagoons;
• identify, on a seasonal scale, the phytoplankton taxa that serve as climate change indicators in deep, marine-influenced and oligotrophic lagoons considered to be climate change sentinels;
• disentangle the effects of climatic, hydromorphological and trophic variables to model the responses of the indicator phytoplankton taxa.

Axis 3. Resilience of lagoon types

• Predict lagoon trajectories based on DRIAS climate scenarios up to 2050, using statistical modelling methods and AI techniques (machine learning);
• identify risk factors and resilience factors relating to lagoons' response to climate change;
• construct conceptual models for each type of lagoon, representing the climate/catchment/lagoon systems, incorporating the identified key variables and their interactions;
• validate these models with local experts (one lagoon per type).

The development of scenarios for the evolution of Mediterranean lagoons will draw on the DRIAS portal, which provides regional climate scenarios based on the IPCC projections.

The findings of the PhD research will be disseminated through high-impact scientific articles and presentations at national and international conferences.

The knowledge gained will also be shared with local stakeholders (users, managers, scientists, local authorities, decision-makers) across the Mediterranean regions. Efforts will be made to disseminate the results to the general public (e.g. video on the YouTube channel Écran de Savoirs' / University of Montpellier).

How are your activities organized?

• Full-time
• Occasional day trips (coastal vessels and small boats)

Who are you?

• A five-year degree in ecology (Master Degree), preferably in marine or aquatic ecology.

Skills, knowledge and experience

• A solid grounding in computational ecology (R software)
• The ability to implement and develop scripts (linear models, multivariate analyses, AI)
• Openness to interdisciplinary approaches
• Writing and communication skills in French and English

Qualities

• Rigorous approach
• Ability to work independently
• Enjoy working as part of a team

Benefits

• We have a teleworking agreement and our staff have 12 comp time days (after 6 months' seniority) and supra statutory leave.
• We allocate a significant budget to developing skills, through individual or collective training actions.
• We have a CSR policy inspired by the purposes of the institute (sustainable mobility allowance, etc.)

Application

Your application file must include in a pdf file :

• a CV
• a reference letter
• an academic transcript (Bachelor's degree + first year of Master's and first semester of second year of Master's).

Next Steps

• Review of your application
• In-person or video conference interview
• Interview before a doctoral school committee, with representatives from the doctoral school and Ifremer
• Approval of your application by the doctoral school council

Job details

Title

Thesis PHYCLIMED Past and future trajectories of MEDiterranean lagoons under CLIMate change : an integrated approach to hydrology and PHYtoplankton M/F - Sète - CDD

:59 (Europe/Paris)

:59 (CET)

Ifremer conceives and operates tools for observation, experimentation and monitoring, and manage the oceanographic databases.