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Biological Impact of Oil Pollution in Arctic and Deep-sea Environment

Periodic Reporting for period 1 - BIOPADE (Biological Impact of Oil Pollution in Arctic and Deep-sea Environment)

Période du rapport: 2017-10-01 au 2019-09-30

The increase of oil demand, associated with the depletion of easily exploitable oil deposits, led the oil industry to intensify the search for new oil areas in the Arctic and deep-sea ecosystems.The BIOPADE project aim was to increase the knowledge base of biological impact assessment of an oil spill in the Arctic and deep-sea ecosystems in the way to conduct potential relevant Spill Impact Mitigation Assessment (SIMA).
This was performed thanks the achievement of three objectives.
(i) Assess the potential long-term impacts of dispersed oil on a key Arctic species. For this, several levels of biological organizations of Gadus morhua were assessed to obtain data coupling both high response sensitivity and ecological relevance. This study reports that short-term impacts of oil compounds on low integration levels are not lasting at an integrative level, thus, highlighting effective compensation phenomena.
(ii) Expand knowledge of dispersed oil impacts in deep-benthic ecosystem. This was achieved using a new methodology on the cold-water coral Lophelia pertusa to directly reach the mitochondria metabolism. The activity of the respiratory chain complexes highlighted the dispersant impact on mitochondrial metabolism.
(iii) Develop bioassays to assess biological impact at depth to provide information on potential behavior and toxicity of chemicals. This was reealized through the adaptation of two classical bioassays (luminescent bacteria and biodegradation tests) at simulated depth.
BIOPADE results provide relevant biological data on the cost and the benefits of the chemical dispersant use in Arctic and deep-sea areas and constitute a valuable input for SIMA in the Arctic and deep-sea areas. Consequently, it gives further information to establish exploitation of oil resources in European marine areas.
The first objective of the project was focused on cod Gadus morhua by an assessment of the fish population using performance trait and more precisely a hypoxic challenge (HC) test (Task1). HC consists in a rapid decrease in water oxygenation until the experiment ended when fish lost their ability to maintain balance
Cods were then exposed to one of the following conditions (Task 2): control, mechanically and chemically dispersed oil or dispersant alone. Three others HC (Task 3) occurred 1, 8 and 24 weeks after the oil exposure. Fisch samplings were performed for biomarkers analysis at the end of the exposure and 2, 9 and 25 weeks post oil exposure.
This study demonstrates that short-term reported impacts of oil compounds on low integration levels are not lasting at an integrative level, thus, highlighting compensation phenomena and plasticity of cods’ fitness. This experimentation will be valorized through two publications: one focused on ecotoxicology and one focused on resistance and adaptation to hypoxia.
The second objective of the project was performed through three tasks. Suspecting compensation phenomena at lower biological organization levels during a first integrative study (TASK 1), we focused deeper in the metabolism of this coral species by adapting the methodology of tissue respiration on L. pertusa (TASK 2) to assess the different complex of the mitochondrial respiratory chain. After validation of this methodology, we used it in an ecotoxicological study on dispersed oil (TASK 3) and highlighted an impact of dispersant on proton leak. Objective 2 will be valorized through the writing of three publications: two on ecotoxicology and one focused on the methodology developed on mitochondria.

The third objective was to develop experimental tools making possible to assess toxicity and behavior of chemicals under high hydrostatic pressure. Firstly, hyperbaric chambers were developed and tested at 180bars to assess their resistance at high hydrostatic pressure (TASK 1). The first protocol was focused on the chemical behaviors under pressure with dodecane biodegradation measurements (TASK 2) by Alcanivorax borkumensis. Dodecane biodegradation were assessed during 24h at 1 and 100bars coupling hyperbaric chambers to an HPLC pump. No biodegradation was observed in both conditions by measuring dodecane and metabolite concentrations by GC-MS but confirming the proof of concept.
Then, a study was conducted on Aliivibrio fischeri, using their bioluminescence as a metabolism indicator (TASK 3). Adapted from an established protocol, photons produced by bacteria were brought to a luminometer, thanks to an optical fiber. After a successful comparative experimentation between our new device and the regular “microtox’’ material at atmospheric pressure, mmeasurements of photons were performed at 100 bars and allowed us to validate the proof of concept of a luminescent bacteria test adapted under pressure.
Authors of this work will improve their works with more data and some adjustments in the way to be able to protect their experimental devices soon with patents.
The experimentation performed on cod were focused on biomarkers of different level of biological organization (gene expression to performance traits). It provides data on potential synergistic short and medium-term effects of oil and dispersant application in the marine Arctic, both with a high response sensitivity and an ecological relevance. The use of hypoxia tolerance as biomarkers of fish functional integrity an Arctic species demonstrated a plasticity in adaptive capacities of juvenile cods. This kind of integrative biomarkers, closely related to the global environmental history of the assessed organism, provide relevant information about the resilience and vulnerability of fish after a stress period.
To obtain ecotoxicological trials in the deep-sea environment, we used two approaches, one with a large range bathymetric species and one by developing under pressure. For the first time, assessment of the different complex of the mitochondrial respiratory chain of Lophelia pertusa were evaluated and used it to observe a potential alteration by dispersant of the internal membrane of mitochondria. This methodology can be applied to several experimental studies in impact assessment using Lophelia pertusa as a model species. In this context of environmental monitoring in deep-sea ecosystem, no standardized bioassay was considering hydrostatic pressure, despite its crucial role on life. The development of mini hyperbaric chambers during BIOPADE project allowed to adapt two classical bioassays to assess the biodegradability and the toxicity of chemicals under high hydrostatic pressure.
By the coordinator supervision, the applicant improved his knowledge in communication skills and ecotoxicological in Arctic and deep-sea ecosystems. This lead, in addition to his research on the BIOPADE project, to the writing of two scientific papers focused on the oil context in Arctic and deep-sea ecosystems. Using this experience in ecophysiology, the applicant provides to the host organization new methodologies in biological impact assessment, coupling high response sensitivity on mitochondria and ecological relevance using performance traits on fish. Furthermore, bioassay developments under pressure will provide the possibility to market this research to private or public organizations. Finally, via the ERASMUS program, a master student course focused on physiology and ecotoxicology has been developed jointly by Brest and Tromsø University.
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