Autumn-expedition to the Tarkhankut gas seep region by HYPOX partner IBSS

In November 2009, the Institute of Biology of the Southern Seas (IBSS) performs a land-based expedition to the Tarkhankut gas seeps region – a shallow area near the Crimea Peninsula. In continuation of the last field trip in September the intention is to follow up on the former investigations and to monitor seasonal changes that may occur. The observations conducted include physico-chemical as well as biological parameters:

Water column above the gas seeps: Dissolved oxygen, oxygen demand, temperature, pH

Seep-associated microbial mats: Sulfide and oxygen, redox-potential, pH, organic matter content (unstable and stable); micro- and macrozoobenthos under hypoxic conditions.

Preliminary conclusions:

Hypoxic conditions in the seep associated microbial mats as well as in the nearby water column prevail also in late autumn. However, compared to the situation in September, oxygen was found to penetrate deeper into the mat while sulfide concentrations decreased. Higher organisms adapted to microbial mats were observed to tolerate high sulphide concentrations and oxygen depletion for at least two months.

Fig. 1: Natasha Orekhova and Yury Vnukov in front of a profiling device that advances microsensors for oxygen and sulfide at 1mm steps into microbial mats (photo - M.Gulin).

Video: Vitaly Timofeev (diving) and Maksim Gulin (operating the rubberboat) take samples of mats, zoobenthos, and the water column (video - N.Orekhova).