- Short- and long-term dynamic processes in marine plankton, their correlation with fluctuations of environmental factors.
- Especially interesting is reaction of plankton organisms to anomalous climatic phenomena as an indication of natural limits of qualitative and quantitative variations of plankton; this may be helpful in analysis of anthropogenic influence on marine ecosystems.
- Zooplankton during winter period: strategies of survival in extreme conditions.
- Zooplankton in meromyctic reservoirs: distribution and dynamics.
- Zooplankton and salinity: influence of spring ice melting and terrestrial run-off.
- Seasonal dynamics and year-to-year fluctuations of zooplankton abundance in Antarctic and dependence of these processes on terrestrial influence (glaciers melting, run-off).
1993-1997 – St.-Petersburg State University, Dept. of Invertebrate Zoology, bachelor of science;
1997-1999 – St.-Petersburg State University, Dept. of Ichthyology and Hydrobiology, master of biology
1999-2002 – postgraduate student (ibidem).
1996 – 1998: the White Sea Biological Station, Zoological Institute, laboratory assistant;
2000 – 2001: the Biological Institute of St.-Petersburg State University, researcher;
2002 – present: the White Sea Biological Station, Zoological Institute, researcher.
Main research areas:
I finished the PhD thesis "Seasonal and long-term dynamics of the zooplankton community in Kandalaksha Bay of the White Sea in connection to water temperature dynamics", which is based on long-term (since 1961) zooplankton and environment monitoring near the White Sea Biological Station. The main goal of this study – to find time scale at which influence of temperature on zooplankton community is significant: season cycle, year-to-year fluctuations, single anomalous deviations from average level or long-term persistent trends. It was observed, that high amplitude of seasonal changes is characteristic for water temperature (up to 20°C at the surface) and also for zooplankton abundance, which changes from 0 to several thousand ind./m3. Extremely warm (1980) and cold (1966) years, and years with anomalously high (1964) and low (1983) zooplankton abundance were found. Quasi-cyclic fluctuations of these parameters with period length from 3 to 23 years and more (exceeding duration of monitoring) were revealed. The timing of spring water warming shifted to earlier time in the beginning of 1970-ies, this marked the beginning of the warm period, which continues up to now. As a result, by 2010 the timing of spring warming (3-5° thresholds) has advanced by almost 20 days. At the same time, timing of Calanus glacialis juveniles appearance has advanced also by 19 days. Timing of this event and timing of spring warming correlate positively (r = 0.6±0.11). All these indicate significance of spring warming course for early development of C. glacialis. Neither year-to-year fluctuations, nor extreme environmental conditions or quasi-cyclical oscillations had significant effect on zooplankton. The only significant correlation was observed between warm-water Temora longicornis and summer water temperature (r = 0.65±0.11). The results of analysis allow us to conclude that degree of water heating is one of the main factors, or trigger, which drives majority of biological processes in plankton during seasonal cycle. However, at the level of year-to-year or long-period changes temperature influences plankton in interaction with many other environmental factors, therefore we cannot reveal direct influence of temperature on zooplankton community dynamics.
Investigations of influence of currents on vertical zooplankton distribution and migrations were started in 2015 in collaboration with oceanologists. The hypothesis of use of currents by zooplankton for distribution or retention in distinct area is being considered. I expect also to reveal joint influence of currents (tidal) and illumination on zooplankton during seasonal change of night/day ratio. Chupa Inlet, where the investigations take place, is a fjord-type basin with currents directed mostly along its axis. So it is a good place for studies of currents influence on zooplankton.
The dynamics of zooplankton in winter period is being studied with the focus on quantitative and qualitative changes during the cold season and long-term abundance in this time of year. Among other, a great instability of timing of warming and ice melting in the White Sea was found, which shifts the spawning of cold water species within 1-2 months. Normally, spawning of these species begins under the ice.
There are many methods for characterization of community structure: indices of dominance or evenness. These indices are extremely rarely used in investigations of zooplankton. I plan to follow changes of these indices in time (during a year) and space (in different parts of the White Sea). It is interesting also to compare communities at different space scales: in bays of the White Sea, in different parts of the same bay and so on. Comparison of community state at different moments ("time sections") and different places is also interesting.
There are some themes, which need additional working hands and time:
- Small-scale vertical distribution of zooplankton. Sampling of plankton in standard layers (0-10, 10-25, 25-50 m etc.) do not always give impression of real space structure of zooplankton community. Observation of narrow layers may reveal small-scale structure of community.
- There are some species in study area, which were not distinguished during monitoring. These are Pseudocalanus acuspes è P. minutus. They demonstrate similar seasonal dynamics, and it is difficult to distinguish between them analyzing only seasonal cycle. However, they can have different ecological traits. So it is important to undertake also morphological analysis to understand life cycle traits of these species.
- Life cycles of some abundant species wait for investigation: Aglantha digitale, Evadne nordmanni, Podon leuckarti, Pleopis polyphaemoides, Fritillaria borealis and some others.
- Species composition of meroplankton and its seasonal changes are poorly studied.
During several years (2003, 2004, 2005 and 2007) I performed observations of zooplankton in the relic meromyctic lake Mogil’noe on Kil’din Island (the Barents Sea). The objectives of this study were: vertical and horizontal distribution of zooplankton, species composition and year-to-year changes of abundance. The dependence of composition and abundance of zooplankton on location within vertical gradient of salinity was revealed. The greatest abundance is typical for the layer with high salinity (>25 psu), whereas the lowest density was recorded in the surface and bottom 3-m horizons (the former is almost fresh, while the latter is poisoned with H2S and depleted of O2). However, in 2007 almost uniform vertical distribution of freshwater species Keratella hiemalis was noticed, which still needs explanation. Marine species prevail in the lake both in species number and abundance. Unexpectedly high abundance of marine Pseudocalanus sp. was found in the marine layer of the lake during all expeditions. This work was supported by the Russian Fund of Basic Research (grant N 07-04-01734-a).
During 5 years (2006-2011) I studied with colleagues zooplankton in the coastal zone of King-George Island (South Shetland Isles, Antarctica). We studied seasonal and year-to-year dynamics of zooplankton abundance and composition, special attention was paid to the influence of gradient "land – open sea" on the qualitative and quantitative characteristics of zooplankton. The amplitude of seasonal and year-to-year fluctuations of temperature and salinity in Ardley Inlet, where investigations took place, were very small. Vertical gradients also were negligible, which points out the importance of intensive vertical mixing in this area. On the contrary, seasonal and year-to-year changes of zooplankton abundance and composition were significant, due to appearance and disappearance of rare species and oscillations of dominant species abundance. Terrestrial influence (either covered with glacier, or not) were expressed in changes of vertical distribution of zooplankton (increase of depth of maximum abundance near shore), and also in changes of total abundance (it decreases in direction to open sea). Open ocean influence manifest itself in the increase of species diversity.
- Exploration, sustainable use and protection of natural resources of the White Sea. Proceedings of the XIII conference, Saint Petersburg, Zoological Institute RAS, 2017, 290 p. (In Russian).
- Usov N.V. 2015. Seasonal and long-term dynamics of the zooplankton community in Kandalaksha Bay of the White Sea in connection to water temperature dynamics. Synopsis of the PhD dissertation. Saint-Petersburg, 26 p.
- A variety of interactions in the marine environment. Abstracts volume from the 49 European Marine Biology Symposium, St.-Petersburg, 2014, 116 p.
- Usov N., I. Kutcheva, I. Primakov, D. Martynova. 2013. Every species is good in its season: Do the shifts in the annual temperature dynamics affect the phenology of the zooplankton species in the White Sea? Hydrobiologia, 706: 11-33.
- Persson J., Stige L.C., Stenseth N.C., Usov N., Martynova D. 2012. Scale-dependent effects of climate on two copepod species, Calanus glacialis and Pseudocalanus minutus, in an Arctic-boreal sea. Marine Ecology Progress Series, 468: 71-83
- Usov NV 2011. Dynamics of zooplankton in the seasonally ice-covered sea in terms of coastal areas of the White Sea. Bulletin of St.-Petersburg State University, Series 3, no. 3:3-14. (In Russian).
- Usov N.V. 2007. Representativeness of sampling by plankton nets with different mesh size. II Scientific conference "Ecological investigations of the White Sea organisms". 18-22 July WSBS ZIN RAS, Cape Kartesh: 138-139. (in Russian)
- Usov N.V. 2007. Long-term dynamics of temperature, salinity and zooplankton abundance in Chupa Inlet of Kandalaksha Bay in summer. Problems of investigation, rational use and protection of natural resources of the White Sea. Materials of X International Conference. Arkhangelsk: 226-230. (in Russian)
- Primakov I.M., Martynova D.M., Usov N.V., Kutcheva I.P. 2007. The main lines of investigation of the White Sea pelagial by the staff of the White Sa Biological Station of Zoological institute RAS. II Scientific conference "Ecological investigations of the White Sea organisms". 18-22 July 2007. WSBS ZIN RAS, Cape Kartesh: 96-100. (in Russian)
- Usov N., Martynova D., Primakov I. 2006. Flexibility of zooplankton community to the hydrological environmental changes in the White Sea. Adaptations of Marine Organisms and Problems of Global Climate Changes. Russian-German Scientific Workshop. - St. Petersburg, April 2006: 16.
- Usov N.V. 2005. About the book "International atlas of ocean", vol. 7. Marine Biology (Biologiya Morya) (Russia), 31, 3: 227. (in Russian)
- Bobkov A.A., Usov N.V., Tsepelev B.Yu. 2005. Hydrometeorological factors influencing temperature anomalies formation near Cape Kartesh. Bulletin of S.-Petersburg State University (Vestnik Sankt-Peterburgskogo Gosudarstvennogo Universiteta). 7, 2: 115-119. (in Russian)
- Berger V.Ja., Primakov I.M., Usov N.V., Kutcheva I.P.. 2004. Monitoring of pelagic zone in the Chupa Inlet of the White Sea. Multidisciplinary studies of Processes, Characteristics and Resources of Russians Seas of the North-East Basin. Apatity. Kola RC RAS, 1, Chap. 7: 215-222.(In Rusian).
- Zubakha M. A., Usov N. V. 2004. Optimum Temperatures for Common Zooplankton Species in the White Sea. Russian Journal of Marine Biology, 30, 5: 293-297. (in English)
- Usov N.V. 2004. Review of book " V. Berger, A. Naumov, M. Zubaha, N. Usov, I. Smolyar, R. Tatusko, S. Levitus 36-Year Time Series (1963-1998) of Zooplankton, Temperature and Salinity in the White Sea. S-Peterburg - Washington, 2003, 362 p.". Oceanology. (Okeanologiya), 44: 9-51. (in Russian)
- Usov N.V. 2003. The winter zooplankton of the Chupa Inlet (the White Sea). Accounting session on the results of work in 2002. ZIN RAS, S.-Petersburg: 35-36. (in Russian)
- Usov N.V. 2003. The winter zooplankton of the Chupa Inlet (the White Sea). Proceedings of the Zoological Institute, S-Petersburg 299: 181-186.
- Berger V., Naumov A., Zubaha M., Usov N., Smolyar I., Tatusko R.,Levitus S. 2003. 36-Year Time Series (1963-1998) of Zooplankton, Temperature and Salinity in the White Sea. S-Peterburg Washington, Silver Springs :362
- Usov N.V. 2000. Influence of year-to-year differences of water temperature on dynamic characteristics of zooplankton. Proceedings of the VIII annual scientific conference "XXI century: the young, ecology, noosphere and stable development" - SPb.: 99. (in Russian).
- Usov N.V. 1999. Life cycles and season dynamics of the most abundant zooplankton species of the White Sea. Proceedings of the VII annual scientific conference "XXI century: the young, education, ecology, noosphere" - SPb.: 106. (in Russian)