Complex studies of the Azov, Black, and Caspian seas performed on the Deneb survey vessel in 2007

Abstract

The study of the modern environmental processes taking place in the Azov and Black seas and in the Caspian region of Russia is one the priority tasks of the Southern Scientific Center of the Russian Academy of Sciences (SSC RAS). The SSC RAS, together with the Murmansk Marine Biological Institute of the Kola Scientific Center of the Russian Academy of Science, has been performing annual marine studies in the south of Russia in the last 10 years [1‐11]. The marine fishing vessel Deneb was bought and upgraded in December 2006, which has significantly allowed expanding the geography of the studies and the volume of the work. In 2007, the survey vessel Deneb performed 4 complex expeditions in the Azov, Black, and Caspian seas (table, Fig. 1). The complex studies included the following: meteorological observations, the study of the hydrological‐hydrochemical regime and the features of the spatial distribution of the plankton and benthos, palaeoecological studies, and realization of ship born observations of birds and marine mammals. The studies were carried out in correspondence with the conventional methods and guidelines for oceanographic studies. Standard equipment was used during the field work: STD probes; Apshtein, Judy, and X plankton nets; Petersen’s and van Vin’s bottom samplers; uniflow sediment tubes; Molchanov’s and BM-48 bathometers; oxygen and pH meters; photocolorimeters; etc. Field chemical analyses (oxygen, hydrogen sulfide, and biogenic elements) were performed in the ship’s chemical laboratory. The analysis of the carbon and nitrogen in the water and the bottom sediments, the analysis of the water ionic composition, and the determination of the heavy metals and oil products were performed in the complex interdisciplinary laboratory of the center using appropriate equipment (a Multi N/C 3100 analyzer, a Kapel’-105 device for capillary electrophoresis, a Kvant Z-ETA atomic absorption spectrometer, and a Spectrum BX FT-IR IR Fourier spectrophotometer). Azov Sea. The marine studies were carried out in the spring (after a mild winter; the temperatures of the air and water were above 0°e with a lack of ice cover), the summer (with anomalously high temperatures of the air and water), and the autumn of 2007. The seasonal fluctuations of the hydrological‐hydrochemical and hydrobiological regime of the water body were studied in the Azov sea. Spring. In the spring period, the expedition took place at increasing cyclonic activity accompanied by relatively low air temperatures ( 7.4–12.0°e ) and a strong east wind (up to 9 m/s). The spatial distribution of the thermohaline fields was studied along the Taganrog‐Kerch’ transect, and it was found that the temperature fluctuated from 12.0 to 9.0°e and the salinity within 3.45‐17.24‰. A stable vertical temperature gradient equal to 0.22°e /m was found in the southeastern part of the sea. The intensive wind agitation conditioned the low clarity of the sea’s water—from 0.4 m in the Taganrog Gulf to 3.5 m in the Kerch strait. The oxygen content in the surface and bottom layers was within 86‐142% and 87‐129% correspondingly, with relatively even distribution over the depth. The biogenic elements’ concentration range was 0‐2 µ g/l for nitrites, 0‐72 µ g/l for nitrates, and 0‐32 µ g/l for phosphates in the surface layer and 0‐13 µ g/l, 0‐20 µ g/l, and 0‐4.5 µ g/l in the bottom layer, correspondingly. A site with an anomaINFORMATION