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Hydrothermal Vents and Cold Seeps
  • Discovery only 1977 by warm seawater at 2500 m depth off Galapagos
  • Hydrothermal activity as warm (5-100°C), diffuse flow from cracks or hot (250-400°C), superheated water from chimneys; temperature around vents is 8-23°C by mixing with cold seawater
  • Hydrogen sulphide (H2S) is common, normally highly toxic to animals
  • New species account for 95% of specimens recovered from hot vents, among them the red tube-worm Riftia sp. (Vestimentifera) and the archaea, a group of evolutionary old and simple bacteria-like cells

    The tube-worm Riftia up to 1.5 m long, 3.7 cm thick, growth 85 cm/yr; tube length up to 3 m; density up to 170 m    -2

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  • Cold Seeps discovered 1984 at the base of the Florida Escarpment at 3270 m depth; hypersaline with sulphide and methane seep out onto the sea-floor; temperature is cold, but species composition similar to hot vents
  • Short-term environments: persist only for serveral years

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  • High biomass but low diversity: only few species adapted to the harsh environmental conditions; 90% of species are endemic to vents and seeps
  • High temperature variance
  • Hydrogen sulphide (H2S) is high, and oxygen concentrations can switch rapidly from oxic to anoxic
  • Salinity ranges from one third to twice the normal deep-sea values
  • Hydrothermal fluid contains high concentration of inorganic substances that precipitate upon contact with seawater and constantly cover the organisms‘ body surface
  • Superheated water contains high metal concentrations (zinc, copper), which form metal-sulphide precipitates but also expose organisms to high concentrations of toxic metals
  • Short-lived and scattered habitat of small size (25-60 m in diameter) requires fast growth, early maturation, high number of offspring, larval dispersal to settle new habitats
Energy Source of Vents and Seeps: H2S
  • Hydrogen sulphide is the primary energy source for hot vents and cold seeps
  • Chemosynthesis by symbiontic bacteria convert H2S into organic material: H2S + CO2 + O2 + H20 = CH2O + H2SO4
  • Detoxification in other animals (mussels, echiurid worm Urechis) is performed by symbiontic bacteria as well

     
Distribution of Hot Vents and Cold Seeps

Links to hot vent and cold seep sites: