ESONET: The Black Sea
With anoxic conditions in the deep, problems with invasive species and high sediment loads delivered to the system, this area has unique problems requiring long term stations.
The Black Sea represents an almost landlocked basin and the largest anoxic water mass on earth. It is a key region for the south European climate as it is the source for the south European rain fall. The coastal zone is densely populated with approximately 16 million inhabitants and an annual 4 million tourists visiting the sea coast. Since the early 70s, there has been a rapid rise in nutrients, organic eutrophication and chemical pollution due to transportation, construction, tourism and the use of pesticides and fertilizers. In addition, high intensity gas seeps, gas hydrates, mud volcanoes and earth quakes are frequent. Both in turn affect the Black Sea biota and biological resources. The intense marine traffic and offshore exploration of oil and gas constitute additional sources of marine pollution.
The biological components of the Black Sea ecosystem are strongly dependent on its geographical position and morphology. The upper water layer, supporting a unique biodiversity of species is so thin and fragile that the effects of pollution, unsustainable fishing or destruction of habitats and landscape result in dramatic ecological changes which have knock-on socio-economic impacts. In deeper anoxic waters, unique microbial ecosystems form reef-like structures above methane seeps. However, knowledge about life in the deep layer is still very limited. The disturbance of the natural balance between the two water layers could trigger irreversible damage to the ecosystem and people of the Black Sea.
Sites of significance
- Zernov's Phylophora fields (unique ecosystem endangered by hypoxia since the 1960s)
- Dnjepr paleo-delta at the shelf margin (shallow, above gas hydrate stability zone, gas plumes cross anoxic/oxic interface and may reach sea surface)
- Dvurechenskiy mud volcano area at the Sorokin Trough (deep, below gas hydrate stability zone, 1000m high gas flare detected 2002)
- Danube Delta (major river discharge)
- Dniestr and Dniepr River mouths
- Varna & Bosporus (earth quake occurrence)
The long-term cabled observatory will provide:
- Continuous data on high intensity gas flares and environmental control parameters of gas and fluid discharge (e.g. bottom currents, microseismicity, earthquakes, gas hydrate stability, role of mud volcanoes)
- Continuous input data for ecosystem approach on adaptive management of the Black Sea to (1) provide evidence for the causes and effects of eutrophication and (2) to assess the effectiveness of measures proposed to control eutrophication
- Protection of this sensitive and unique European ecosystem
Bathymetry of the Paleo Dnepr delta area with position of hydro-acoustically detected gas flares.
Sea floor features in Black Sea. Bacterial mats, encrustaceans and gas bubbles streaming upwards from vents. Images courtesy GHOSTDABS - Hamburg University.
The proposed regional network in the Black Sea. The putative cable routes in pink are not realistic the lines simply link sites of interest.
3D map of the proposed regional network in the Black Sea.