Deoxygenation is a major global environmental problem affecting marine waters and is among the most widespread deleterious anthropogenically induced consequences which may be catastrophic for living organisms. Oxygen Minimum Zones (OMZs) may appear in various parts of the ocean where water ventilation is not able to renew the O2 consumed by respiration. In the coastal area, the occurrence and expansion of OMZs mainly result from the combined action of climate warming that reinforces the stratification (i.e. stronger and longer stratification, lower solubility of oxygen) and anthropogenic eutrophication that enhances the amount of organic matter to remineralize.
The BENTHOX project is targeted towards the understanding of marine coastal hypoxia and its consequences on benthic-pelagic exchanges, diagenesis and ecosystem functioning. It aims at developing appropriate assessment tools and methodologies to better understand the mechanisms behind coastal hypoxia and its impact on the status of the benthic ecosystem and biogeochemical cycling. Since the benthic compartment is a key player in the occurrence of coastal OMZs, a lot of efforts will be devoted to the modelling and understanding of this compartment which has been often oversimplified in previous ocean models.
BENTHOX addresses the following key scientific questions (KSQ):
1) What is the impact of bottom hypoxia on benthic nutrient cycling, benthic-pelagic fluxes and the activity of benthic organisms?
2) Which (paleo)-proxies can be used to reconstruct the long term history of hypoxia?
3) Which tools can be used to provide management strategies that will control the level of bottom hypoxia and preserve the Good Environmental Status (GES) of marine waters?
4) Which tools can be used to investigate and differentiate the drivers of bottom hypoxia?
The Black Sea is chosen as a pilot area because the occurrence of hypoxia is shown to significantly increase between the 70's and the 90's, implying modifications of the benthos. Some regions of its north-western shelf (NWS) are still seasonally affected by hypoxia.
BENTHOX is a 4-year project (1/10/2015-30/09/2019) financed by the FNRS.
BENTHOX proposes to use a holistic and interdisciplinary approach combining field surveys and data collection, mathematical modelling, statistical analysis and diagnostics computation. The Black Sea north-western shelf (BS-NWS) which exhibits seasonal hypoxia has been chosen as a test case area. Specific data will be collected in order to link locally the O2 level, the benthos composition, the benthic-pelagic fluxes and sediment processes. New data will be collected in the framework of a EU-United Nations Development Program EMBLAS (Environmental Monitoring in the Black Sea, http://emblasproject.org/).
New data sets (benthic-pelagic fluxes, biodiversity) that will be included in international data bases/Parameterization of benthic-pelagic fluxes that can be incorporated in large scale models and tested in hypoxic environments
Assessment of the impact of hypoxia on benthic fluxes, diagenetic pathways, and biodiversity.
Identification of paleo-proxies of hypoxia and reconstruction of the long term history of hypoxia in the Black Sea since the Holocene.
Multi-decadal assessment of hypoxia variability in answer to eutrophication and climate change