Abstract
The variability of sea ice in the Weddell Sea, along with melting of glaciers of the Antarctic Peninsula and ice shelves, determines the volumes of melt water entering the water area, which, among other things, affects the hydrophysical conditions of phytoplankton development. Based on the materials of a scientific cruise carried out in the Powell Basin in January–February 2020, the spatial distribution of melt water content and its influence on the hydrophysical structure of the surface layer, the vertical distribution of fluorescence values and, the content of chlorophyll a were investigated. Areas with the highest freshening were identified in the eastern part of the Powell Basin (shelf of the South Orkney Islands) and in the southwestern part of the basin in the area of ice removal from the Weddell Sea to the north. The least freshening was recorded in the northwestern part of the Powell Basin. It is shown that the distribution of melt water was the main factor enhancing the vertical stability of the surface layer. An increase in vertical stability led to the formation of hydrophysical environmental conditions preventing vertical mixing, which affected the development of phytoplankton communities, namely, their concentration within a limited depth range in the surface layer. In the absence of other factors limiting phytoplankton development in these, well-shown peaks of chlorophyll concentration in the 0–50 m layer were formed. These zones included the shelf area of the South Orkney Islands and northern boundary of the Powell Basin. In areas with an insignificant freshening effect, the fluorescence peaks were diffuse; the phytoplankton community developed in a wider depth range of the surface layer.
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ACKNOWLEDGMENTS
The authors thank the scientific staff of the expedition and crew of the R/V Akademik Mstislav Keldysh for their assistance in obtaining the data. The authors are grateful to Deputy Head of the Expedition, Doctor of Biological Sciences V.A. Spiridonov for discussing the idea of the study.
Funding
The study was carried out under a state task (topic no. 0128-2021-0017). Processing of hydrophysical data was supported by a grant of the President of the Russian Federation (MK-1492.2021.1.5). The data for the analysis of the thermohaline structure were collected on a cruise of the R/V Akademik Mstislav Keldysh with the support of the Russian Science Foundation (grant no. 21-77-20 004).
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Izhitskiy, A.S., Romanova, N.D., Vorobieva, O.V. et al. Impact of Ice Melting on Oceanographic and Hydrobiological Characteristics of Surface Waters in the Powell Basin, Weddell Sea, in January–February 2020. Oceanology 62, 439–446 (2022). https://doi.org/10.1134/S0001437022040154
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DOI: https://doi.org/10.1134/S0001437022040154