MOLLUSCS TO MONITOR WATER QUALITY
Three years of experiments in the Barents Sea
Effective, reliable ecosystem monitoring is an integral part of the process for reducing the environmental risks associated with our industrial activities. This is especially true when we operate in vulnerable or difficult-to-access areas, such as extremely cold regions where harsh weather conditions require that we minimize the number of human interventions.
In 2012 we began testing high-frequency non-invasive valvometry, an innovative online biomonitoring technique, under these conditions as a possible alternative to existing physical-chemical monitoring solutions.
The method consists of continuously monitoring the bivalves' opening and closing cycles to detect behavioral disturbances associated with environment alterations, particularly hydrocarbon pollution. Any stress or stimulation leads to a significant increase in the valve activity of these invertebrates.
The in situ experiment was conducted in collaboration with the University of Bordeaux and CNRS (France) as well as the Murmansk Marine Biology Institute (MMBI, Russia). Two valvometers (Mytilus edulis mussels and Chlamys islandica scallops equipped with micro-sensors) were tested in the shallow waters of the Barents Sea near the MMBI coastal research station in Dalnie Zelentsy. A probe was also installed in October 2014 to continuously monitor water quality (temperature, nutrient levels, turbidity), so that we could refine our interpretation of the valvometric readings. All data were continuously transferred directly to the University of Bordeaux for analysis and available to the public in real time online.
Ultra-high performance biomonitoring
Data were collected continuously in two sets: the first lasting one year (October 2012 to September 2013) and the second almost two years (October 2014 to July 2016) with no major technical failures recorded, demonstrating the feasibility of our biomonitoring project. We achieved our initial goal of creating a system capable of functioning without interruption for at least one year, requiring zero maintenance and having no adverse effect on quality of life for the animals involved.
The analysis of mollusk valve activity enabled us to monitor the changes in natural environmental conditions (day/night alterations, tidal effects, etc.) and the health of the animals (biological rhythms, growth rate, spawning season). Scallop births, observed for the first time under these experimental conditions (bivalves equipped with micro-sensors living in a cage), demonstrated that these animals had no trouble adapting to the device. No negative impact on their well-being from the experimental system was observed.
Eliminating the need for maintenance over such a long period of time is a decisive advantage for valvometry over traditional offshore monitoring techniques that require frequent upkeep due to incrustations (algae or bacteria). And this is not the only selling point.
It is also an extremely effective monitoring tool. Twice, once in the summer and once in the winter, we exposed the valvometers to small quantities of hydrocarbons, which were introduced for a brief period of time under controlled conditions approved by local authorities. These tests confirmed the animals' extreme sensitivity to pollutants, 10 to 100 times greater than that of typical physical-chemical probes and detectors. This sensitivity was documented during previous tests in the laboratory and in a controlled (freshwater) environment at the Pilot Rivers experimental site of the Lacq Study and Research Hub.
Extremely cost-effective and requiring very little power, this technology also provides a continuous stream of data in real time that can be sent to a monitoring office or a website accessible to our stakeholders.
Toward operational valvometry
Some work must still be done before valvometry can be considered a fully operational system. For instance, as there are many events that might affect the valve activity of mollusks in their natural habitat, we must be able to confidently tell which are caused by the presence of hydrocarbons resulting from chronic spills or accidental leaks.
This is the goal of the work begun with the University of Bordeaux in January 2016, whose primary objective is to test the animals' reaction (valve behavior, physiology) when presented with multiple stressors (hydrocarbons, metals, noise, turbidity, etc.).
With several operational pilot tests in progress, the aim now is to extend the scope of application for this technology to our various area of operation, particularly tropical regions, so that it can be used to perform environmental monitoring for our offshore or coastal activities.
RESTORING DEGRADED CORAL ECOSYSTEMS
Why are coral reefs — “the rainforests of the sea” — so important to marine biodiversity?
Coral reefs are built on a symbiotic relationship between sea animals (scleractinian corals) and micro-algae (zooxanthellae). They occupy less than 0.1% of the ocean floor but are home to 25% of all marine species, illustrating their crucial role in marine biotopes.
Primarily located in shallow coastal areas, coral reefs provide a wide range of ecosystem services (see below) and play a key role in protecting shorelines from erosion and waves. By trapping carbon in their calcium carbonate skeletons throughout their lifespan, corals also create a vast carbon sink that helps reduce the amount of carbon dioxide (CO2) in the atmosphere.
Severe bleaching has affected corals in the Middle East, in certain seas in Asia and in the Pacific Ocean. What solutions can TotalEnergies provide to counter this loss of biodiversity?
We created the REEF program in response to a lack of sustainable and realistic operational solutions for the large-scale restoration of coral reefs. REEF is part of our efforts to reduce the environmental impact of our operations. But it’s important to recognize that certain global phenomena will continue to have a decisive impact on ecosystem health and development.
And let’s not forget that coral reef restoration is still in its infancy. The traditional approach, which was used at Yemen LNG in the early 2000s, involved taking cuttings and transferring the corals from one area to another. This method works but it requires many onsite diving hours, which represent a significant cost and a considerable safety risk for the teams involved. The translocation of corals from nurseries (known as “coral gardening”) is another technique currently in use.
New methods are also being developed, such as the sexual propagation approach, which is based on larval capture and rearing. However, this method has only been tested to date on a small number of species. Sinking manmade structures to enhance natural recolonization is still a fairly rare occurrence....
Can you tell us a bit about the REEF project?
REEF started out in 2016 in partnership with Seaboost. The aim is to restore coral reefs using an innovative solution to passively catalyze the coral colonization process. The solution is based on the development of an artificial object (REEF module) whose characteristics (structure, shape, roughness, porosity, pH, materials, etc.) encourage the spontaneous settlement of coral larvae (planulae), and their development and survival.
Once colonized by the corals, the REEF module is moved to a damaged area to enable reseeding (i.e. larvae released by the coral colonies on the REEF module). This produces a domino effect, triggering the restoration of large swathes of coral reefs over long distances.
Different test phases will be conducted up until 2021, in cooperation with the Center for Island Research and Environmental Observatory (CRIOBE) on the Island of Moorea in French Polynesia. These tests will enable us to assess the biocompatibility and performance levels of the different materials and surfaces chosen, so that we can build artificial structures capable of encouraging coral settlement, development and growth. Our research work is crucial in determining the properties required to optimize the settlement and survival of coral colonies on the REEF modules, in terms of both quantity and diversity.
In early 2020, as part of a trial developed in collaboration with Qatar University and the Total Research Center - Qatar (TRC-Q), we will submerge 18 REEF modules in the Persian Gulf at water depths of 20 meters. After around two years, some of the colonized modules will be relocated to test their mobility. The trial will be included in a thesis on coral restoration and underwater monitoring.
What hopes do you have for the world’s coral reefs, thanks to the REEF program?
Designed specifically for the large-scale restoration of coral reefs, this type of movable structure could be placed in coral sanctuaries for colonization as a preventive measure, and then transferred to a damaged area when needed.
The aim is to facilitate recolonization and a gradual build-up of resilience — two objectives that generally require many years to achieve and may even be impossible without human intervention. Little by little, we hope that degraded coral reefs will recover and reclaim their role in biodiversity.
REEF modules have been designed so that they can be produced, installed and maintained by local communities. They therefore contribute to social and industrial development, while also generating a net positive impact for the communities concerned.
For more information:
- Innovative techniques - Environment - PERL