Mollusks Continuously Monitoring Water Quality
Bivalves are in a unique position to observe the quality of their natural habitat, and could be vital allies when it comes to measuring and testing the impact of our industrial activities. A cost-effective, robust solution that minimizes the need for maintenance, biomonitoring through valvometry is one idea being explored by R&D to fulfill Total’s commitments as a responsible operator.
The driving force behind Total’s competitiveness
Nearly 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.
Researchers begin placing the bivalves into the water at the Dalnie Zelentsy experimental site in Russia.
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 the environment, particularly hydrocarbon pollution. In these invertebrates, any stress or stimulation leads to a significant increase in valve activity.
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 and 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 made available to the public in real time online.
Highly effective 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.
Scallop (Chlamys islandica) equipped with sensors.
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 and 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 River 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.
Rendering valvometry operational
Blue mussel (Mytilus edulis) equipped with an electrode.
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 and physiology) when presented with multiple stressors (hydrocarbons, metals, noise, turbidity, etc.).
The aim is to complete demonstration pilot tests by 2018 and 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.