Responsable scientifique
Research team / laboratory

Laboratoire LEAD

Mail
Hugues.Lemonnier@ifremer.fr
Téléphone
285 171
Logo organisme
Ifremer

ECOMINE

The lagoon of New Caledonia has an exceptional marine biodiversity, which has to be preserved face to strong environmental issues due to territory development. The mining industry and coastal urbanization represent a threat to marine biodiversity by increasing terrestrial inputs of organic matter and contaminants into coastal systems through riverine run-offs during cyclonic periods. In the area, the potential impacts of terrestrial inputs on marine microorganism diversity and community structure is not clearly defined at both temporal and spatial scales. Based on the coupled approach between environmental genomics (eDNA), coastal hydrology and geochemistry, this project will aim at understanding human activity impacts over microbial communities under three different and complementary perspectives:

1) Understanding the impacts of mining on microbial communities along the land-sea continuum at different time scales

(2) The analysis of shifts in microbial communities occurred over the last century in parallel to the development of the mining industry by means of the analyse of paleoarchives (sedaDNA and heavy metals) collected from sediment cores

(3) Develop health risk indicators to assess the arrival and/or the recrudescence of blooms of potential harmful microorganisms in relation to human activity development.

Promoting organization

Hugues Lemonnier

Responsable scientifique
Research team / laboratory

Laboratoire LEAD

Mail
Hugues.Lemonnier@ifremer.fr
Téléphone
285 171
Logo organisme
Ifremer
Project start date
May 2021
Estimated end date of project
December 2022
Accordéon

New Caledonia has exceptional terrestrial and marine biodiversity that must be preserved in the face of environmental pressures associated with land development and global warming. By increasing the inputs of contaminants, nutrients and organic matter into hydrosystems, human activities pose a threat to this biodiversity and the associated ecosystem services.

According to the "one health" concept, the resulting degradation is also a source of risk for human health and more particularly in terms of epidemics. The implementation of a regulation to protect and / or restore these hydrosystems requires defining their ecological states. About 300 methods have been developed around the world to characterize the state of environments, whether associated with fresh, brackish and marine waters. For example, the diatomaceous index is used today in the territory to characterize the ecological quality of watercourses. However, the tools developed so far remain expensive and their implementation sometimes takes a long time. However, in the context of climate change, it is important to put in place rapid tools to improve our ability to detect changes early in order to provide solutions to maintain the integrity (function and service) of ecosystems. .

In recent years, a new generation of tools with the ability to provide more complete information and in a faster manner has emerged through the characterization of communities by environmental DNA sequencing (eDNA). These tools are particularly well suited to monitoring microbial communities which are considered to be early indicators of environmental variations.

By combining environmental genomics (eDNA) and geochemistry approaches, this project will aim to (i) understand the impacts of mining activity on microbial communities at different time scales (annual, decadal, centennial) along the earth continuum - sea and (ii) to develop biotic indicators of the health of hydrosystems and coastal ecosystems and (iii) of health risks. Mining activity is targeted here because it is considered the main source of metal contaminants in ecosystems located downstream. The analyzes will be carried out to dissociate two types of impacts associated with this activity: deforestation which modifies the cycle of organic matter and the contribution of metals favored by the erosion of the zones put into exploitation. This work should make it possible to assess the capacity of ecosystems to absorb mining pressures through the analysis of the spatio-temporal variability of their structure and to identify new tools sensitive enough to detect changes at an early stage.

To carry out this study, three zones will be targeted in order to cover the different ultrabasic contexts of New Caledonia: the VKP zone made up of the Koniambo watersheds, the one south of Nouméa made up of the watersheds of the pirogues river and the river. Coulée and an area on the east coast made up of the Thio watershed. These study areas will allow us to take advantage of the achievements of research projects led by CRESICA (Tremor and Searsé) and CNRT (ADIIP, Dynamine, IMMILA, Quavar, Chronick) in geochemistry and sedimentology. The work will be carried out in two phases.

In the first phase, we will collect surface sediment samples, describe them and analyze them both in terms of eDNA and geochemistry. A minimum of five sites will be sampled per zone in the dry season and in the wet season, for a total of 30 samples for this phase. They will be positioned along the land - sea continuum. The second phase of the project will aim to reconstruct changes in microbial communities in parallel with the development of the mining industry, via the analysis of sedimentary archives by harvesting three sedimentary cores. about 1 to 2 meters deep. The choice of site will depend on the siltation conditions observed during the first sampling phase. About 40 samples will be selected for analysis of their ancient DNA content and chemical properties.

Les 28 et 29 mars 2022, le CRESICA organisait le séminaire "Au fil de l'eau" qui a permis de présenter l'état d'avancement du projet.

 

Visionnez la présentation fait lors du séminaire grâce à la vidéo du projet ECOMINE par H. Lemonnier.

 

Le 29 août 2023, le CRESICA organisait le séminaire de restitution "Au fil de l'eau" qui a permis de présenter les résultats du projet.

 Brochure: "Des projets de recherche sur la thématique de l'eau en Nouvelle-Calédonie."

Visionnez la présentation faite lors du séminaire grâce à la vidéo du projet ECOMINE par H. Lemonnier

Partenaires associés
Statut du projet
Projets achevés

SEARSE

For over 20 years, New Caledonia has been recognised as a global biodiversity hotspot possessing one of the world’s highest concentrations of endemic species. New Caledonia is encircled by the world’s largest coral reef complex.
 

Current economic, demographic and social changes in New Caledonia mean that coastlines and coastal environments are subject to increasing human-induced pressures.
The rivers play a key role in transporting sediments and dissolved constituents. Although these sedimentary loads are essential to the dynamics of coastal ecosystems, excess amounts may be harmful (nutrients, trace metals and other contaminants).
The SEARSE project aims to:
•    qualify and quantify sedimentary loads carried by rivers;
•    track them as they form sediment plumes in the lagoon around the Greater Noumea area;
To this end, analyses targeting concentrations of dissolved and particulate matter at outflows will be carried out, and the fate of sediment plumes in the lagoon environment around Greater Noumea will be monitored.
The SEARSE project will use the deterministic GR4J rainfall-runoff model, developed in 2017 by the LEAD team, and the Mars 3D hydrodynamic model developed by IFREMER.

 

Promoting organization

Hugues Lemonnier

Responsable scientifique
Research team / laboratory

Laboratoire LEAD

Mail
Hugues.Lemonnier@ifremer.fr
Téléphone
285 171
Logo organisme
Ifremer
Project start date
April 2018
Estimated end date of project
December 2020
Accordéon

New Caledonia is a vast territory possessing an exclusive economic zone (EEZ). Its maritime area comprises a variety of coral reef formations, lagoon areas, mangroves and very extensive expanses of ocean and seas.

New Caledonia’s exceptionally preserved marine biodiversity was recognised by the 2008 inscription of a majority of the lagoon and reef systems as a World Heritage Site (UNESCO).

For over a century, the mining industry has played a significant role in shaping the country’s landscapes and coastlines but there is an increasingly strong commitment to diversifying the economy and developing tourism and other sectors by leveraging factors such as the country’s attractiveness.

The vulnerability of these tropical ecosystems is a key issue both in terms of research and in terms of the challenges of achieving sustainable management (Territorial Innovation Strategy, 2015).

Any assessment of the environmental status of marine ecosystems must take into account the various human-induced pressures on the environment.

The fact that there is currently no quantification of human-induced pressures makes it very difficult to reach a clear understanding of the structuring processes which affect the integrity of this natural heritage and the related ecosystem services.
Adopting an ecosystem approach is vital to the implementation of an Integrated Coastal Ecosystems Management (ICZM) system.

 

Rivière la coulée –  copyright Elise Coignot
La Coulée river - Copyright Elise Coignot

 

Ultimately, the SEARSE project should make it possible to:

•    model the fate of dissolved compounds in the marine environment;
•    analyze the fate of some contaminants in the marine environment;
•    provide data allowing hydrologic landscapes in the lagoon around Greater Noumea to be defined and mapped.

With the goal of reaching a clearer understanding of:

•    ecosystem functioning in New Caledonia’s lagoon;
•    connectivity between lagoon fish communities;
•    initial sources of trace metal accumulation in the food chain.

The SEARSE project aims to conduct:

•    analyses of concentrations of dissolved and particulate matter at 4 outflows: the Dumbea, La Coulée, Rivière des Pirogues and Tontouta rivers;
•    monitoring of sediment plumes in the lagoon environment around Greater Noumea.

Analyses will identify essential characteristics for each river and quantify sedimentary loads carried by rivers into New Caledonia’s lagoon:

•    total suspended solids (TSS)
•    nutrients (ammonium, nitrates, phosphates and silicates)
•    metals (Cr, Ni, Fe, Mn, Cu, Zn and Al),
•    nitrogen, carbon and phosphorus,
•    organic material in dissolved and particulate form (including COD, CDOM and FDOM),
•    biological particles (bacteria and phytoplankton).

The monitoring process aims to:

•    establish maps of hydrological landscapes;
•    estimate the influence of fluvial loads on these landscapes.

 

carto dumbea, la coulée, la rivière des pirogues copyright Elise Coignot
Mapping of the Dumbea, La Coulée, Rivière des Pirogues rivers - Copyright Elise Coignot

 

Prélèvement avec bouteille Niskin  Copyright Hugues Lemonnier
Sampling using Niskin bottle
Copyright Hugues Lemonnier

The SEARSE project will conduct analyses based on the deterministic GR4J rainfall-runoff model to quantify sediment exports of dissolved and particulate matter from rivers.

This model, developed in 2017 by the IFREMER LEAD team, is designed to estimate river flows on an hourly time-step, from rain data.
These analyses were conducted in four Greater Noumea catchments (Desclaux et al., 2018).

A 300-m hydrodynamic model was developed around the Greater Noumea area to analyse the fate of river outflow waters.

Analyses will be linked to data rates from the GR4H model, with water characteristics at the 4 outflows (Dumbea, La Coulée, Rivière des Pirogues, La Tontouta).

The purchase of drifting buoys will allow tracking of the fate of the plumes and various materials that make up the lagoon.
There will be a special focus on the fate of genetic and functional diversity in microorganisms, excellent markers of environmental changes in the plumes.

This research work will be carried out as part of the assignment of an IFREMER expert from France.

 

Progress report on the monitoring of rivers at outflows in the south of New Caledonia, available at: https://archimer.ifremer.fr  

Boher L., Coignot E., Lopez E., Royer F., Lemonnier H., 2018. Monitoring fluorescent organic materials upstream from estuaries in the south of New Caledonia. End of contract report CSD IFREMER-LEAD. p. 38

Mot-Clé(s): Rivières, Matière organique fluorescente, dynamique


The workshop of the programm "Au fil de l'eau" took place on 17 and 18 September 2019, at the UNC.

Tuesday 18 September was dedicated to the intermediate results of the "Au fil de l'eau" program (whose presentation is available on the french's page of the project). This restitution day was an opportunity to exchange on the various projects that make up the program, between research professionals, actors from the public, private and associative sectors working on these themes.

 

 

Les 28 et 29 mars 2022, le CRESICA organisait le séminaire "Au fil de l'eau" qui a permis de présenter les résultats du projet.

 

Brochure : "Quel bilan après trois années de projets de recherche sur la thématique de l'eau en Nouvelle-Calédonie ? "

 

Rapport final : projet SEARSE

Visionnez la présentation faite lors du séminaire grâce à la vidéo du projet SEARSE par H. Lemonnier.

 

Partenaires associés
Statut du projet
Projets achevés