Project: Interannual Variability in the Antarctic-Ross Sea (IVARS): Nutrients and Seasonal Production

NSF Award Abstract:
During the past few decades of oceanographic research, it has been recognized that significant variations in biogeochemical processes occur among years. Interannual variations in the Southern Ocean are known to occur in ice extent and concentration, in the composition of herbivore communities, and in bird and marine mammal distributions and reproductive success. However, little is known about the interannual variations in production of phytoplankton or the role that these variations play in the food web. This project will collect time series data on the seasonal production of phytoplankton in the southern Ross Sea, Antarctica. Furthermore, it will assess the interannual variations of the production of the two major functional groups of the system, diatoms and Phaeocystis Antarctica, a colonial haptophyte. The Ross Sea provides a unique setting for this type of investigation for a number of reasons. For example, a de facto time-series has already been initiated in the Ross Sea through the concentration of a number of programs in the past ten years. It also is well known that the species diversity is reduced relative to other systems and its seasonal production is as great as anywhere in the Antarctic. Most importantly, seasonal production of both the total phytoplankton community (as well as its two functional groups) can be estimated from late summer nutrient profiles. The project will involve short cruises on the US Coast Guard ice breakers in the southern Ross Sea that will allow the collection of water column nutrient and particulate after data at specific locations in the late summer of each of five years. Additionally, two moorings with in situ nitrate analyzers moored at fifteen will be deployed, thus collecting for the first time in the in the Antarctic a time-series of euphotic zone nutrient concentrations over the entire growing season. All nutrient data will be used to calculate seasonal production for each year in the southern Ross Sea and compared to previously collected information, thereby providing an assessment of interannual variations in net community production. Particulate matter data will allow us to estimate the amount of export from the surface layer by late summer, and therefore calculate the interannual variability of this ecosystem process. Interannual variations of seasonal production (and of the major taxa of producers) are a potentially significant feature in the growth and survival of higher trophic levels within the food web of the Ross Sea. They are also important in order to understand the natural variability in biogeochemical processes of the region. Because polar regions such as the Ross Sea are predicted to be impacted by future climate change, biological changes are also anticipated. Placing these changes in the context of natural variability is an essential element of understanding and predicting such alterations. This research thus seeks to quantify the natural variability of an Antarctic coastal system, and ultimately understand its causes and impacts on food webs and biogeochemical cycles of the Ross Sea.

Related publications:
Smith, W.O., Jr., M.S. Dinniman, J.M. Klinck, and E. Hofmann. 2003. Biogeochemical climatologies in the Ross Sea, Antarctica: seasonal patterns of nutrients and biomass. Deep-Sea Res. II 50: 3083-3101.

Smith, W.O., Jr., A.R. Shields, J.A. Peloquin, G. Catalano, S. Tozzi, M.S. Dinniman and V.A. Asper. 2006. Biogeochemical budgets in the Ross Sea:  variations among years. Deep-Sea Res. II 53: 815-833.

Tremblay, J.-E. and W.O. Smith, Jr.  2007. Phytoplankton processes in polynyas.  In:  Polynyas: Windows to the World’s Oceans (W.O. Smith, Jr. and D.G. Barber, eds.), Elsevier, Amsterdam, Pp. 239-270.

Smith, W.O. Jr. and D.G. Barber (Eds.).  2007. Polynyas: Windows to the World’s Oceans. Elsevier, Amsterdam. 437 pp.

Smith, W.O. Jr. and D.G. Barber. 2007. Polynyas and climate change: a view to the future.  In: Polynyas: Windows to the World’s Oceans (W.O. Smith, Jr. and D.G. Barber, eds.), Elsevier, Amsterdam, Pp. 409-417.

Smith, W.O. Jr., D.G. Ainley and R. Cattaneo-Vietti. 2007. Trophic interactions within the Ross Sea continental shelf ecosystem. Phil. Trans. Roy. Soc., ser. B 362: 95-111.

Peloquin, J. A., and W. O. Smith, Jr.  2007. Phytoplankton blooms in the Ross Sea, Antarctica: Interannual variability in magnitude, temporal patterns, and composition. J. Geophys. Res. 112: C08013, doi:10.1029/2006JC003816.

Smith, W.O. Jr. and J.C. Comiso. 2009. Southern Ocean primary productivity: variability and a view to the future. In Smithsonian at the Poles: Contributions to International Polar Year Science (I. Krupnik, M.A. Lang, and S.E. Miller, Eds.), Smithsonian Inst. Scholarly Press, Washington, D.C., pp. 309-318.

Smith, W.O. Jr., M. Dinniman, G.R. DiTullio, S. Tozzi, O. Mangoni, M. Modigh and V. Saggiomo. 2010. Phytoplankton photosynthetic pigments in the Ross Sea: Patterns and relationships among functional groups. J. Mar. Systems 82: 177-185.

Smith, W.O. Jr., V. Asper, S. Tozzi, X. Liu and S.E. Stammerjohn. 2011a. Surface layer variability in the Ross Sea, Antarctica as assessed by in situ fluorescence measurements. Prog. Oceanogr.  88: 28-45 (doi: 10.1016/j.pocean.2010.08.002).

Smith, W.O. Jr., A.R. Shields, J. Dreyer, J.A. Peloquin and V. Asper. 2011b. Interannual variability in vertical export in the Ross Sea: magnitude, composition, and environmental correlates. Deep-Sea Res. I 58: 147-159.

Liu, X. and W.O. Smith, Jr.  2012. A statistical analysis of the controls on phytoplankton distribution in the Ross Sea, Antarctica. J. Mar. Systems 94: 135-144.

Smith, W.O. Jr., P.N. Sedwick, K.R. Arrigo, D.G. Ainley, and A.H. Orsi. 2012. The Ross Sea in a sea of change. Oceanography 25: 44-57.

Peloquin, J., C. Swan, N. Gruber, M. Vogt, H. Claustre, J. Ras, J. Uitz, J-C. Marty, R. Barlow, M. Behrenfeld, R. Bidigare, H. Dierssen, G. DiTullio, E. Fernandez, C. Gallienne, S. Gibb, R. Goericke, L. Harding, E. Head, P. Holligan, S. Hooker, D. Karl, T. Knap, M. Landry, R. Letelier, C.A. Llewellyn, M. Lomas, M. Lucas, A. Mannino, J.-C. Marty, B. G. Mitchell, F. Müller-Karger, N. Nelson, C. O'Brien, B. Prezelin, D. Repeta, W. O. Smith, Jr., D. Smythe-Wright, R. Stumpf, A. Subramaniam, K. Suzuki, C. Trees, M. Vernet, K. Wasmund, and S. Wright. 2014. The MAREDAT global database of high performance liquid chromatography marine pigment measurements.  Earth System Science Data 5: 109-123.

Smith, W.O. Jr., D.G. Ainley, K.R. Arrigo, and M.S. Dinniman. 2014. The oceanography and ecology of the Ross Sea.  Annu. Rev. Mar. Sci. 6: 469-487.

Smith, W.O., Jr. and K. Donaldson. 2015. Photosynthesis-irradiance responses in the Ross Sea, Antarctica: a meta-analysis. Biogeosciences 12: 1-11.

Asper, V.L. and W.O. Smith, Jr. Variations in the abundance and distribution of aggregates in the Ross Sea, Antarctica. Deep-Sea Res. I (submitted).

Smith, W.O., Jr. and D.E. Kaufman. Particulate organic carbon climatologies in the Ross Sea: evidence for seasonal acclimations within phytoplankton. Prog. Oceanogr. (submitted).