Sea ice biological communities and nutrient dynamics in the Canadian Basin of the Arctic Ocean.

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Melnikov I.A., Kolosova L.G., Welch H.E. and L.S. Zhitina

Salinity, concentrations of silicate (Si), phosphate (P), andchlorophyll a (chl a), andthe species composition of floral andfaunal communities were assessedin multi-year (MY) andfirst-year (FY) ice, and at the water-ice interface, during the SHEBA ice camp drift in the Canadian Basin of the Arctic Ocean, October 1997-October 1998. Mean integrated salinity values variedfrom 0.1 7 0.8% within the snow-ice boundary to 3.2 7 1.46% at the water-ice interface in the MY ice. Salinity of FY ice increasedwith increasing ice thickness, from 0.41 7 0.19% in October to 3.397 1.75% in March. We foundvery low concentrations of both Si andP in MY andFY ice in late fall (<0.01 mM), after the summer season of 1997. Mean integratedconcentration of nutrients increasedwith the freeze-up of ice, reaching maximum values in the summer of 1998. Ice algal biomass was dominated by diatoms in the MY and FY ice, with more pennate than centric species. Species of dinoflagellates and green algae were subdominant. Green algae, typically confined to the upper part of the ice, were distributed throughout the ice thickness. During summer, the brackish-water green alga Ulothrix implexa formedlong rope-like tufts attached to the hull of the icebreaker; development of this species has not previously been observedin the central Arctic Ocean. Biomass, cell abundance andchl a concentrations were high in the bottom sections of both MY and FY ice during the pre-freezing period, then decreased in winter and reached maximum values in spring andsummer. The total algal biomass showeda pattern similar to chl a dynamics, decreasing from 1.7 mg Cl_1 in October to values < 0.1 mg C l~ in winter. Algal carbon biomass andchl a concentration co-variedsignificantly in the FY ice (r2 = 0:79), but less so in the MY ice (r2 = 0:49). An unexpectedfeature with respect to sea ice invertebrates was the absolute absence of living interstitial fauna within the interior of MY and FY sea ice. In addition, the under-ice fauna was species-poor. Comparisons of SHEBA results with historical data showed that the physical-chemical characteristics of sea ice and the biological structure of ice communities found in this study were very different from conditions during the 1970s. It is likely that the changes resulted from increased melting of the arctic ice pack over the last two decades. © 2002 Publishedby Elsevier Science Ltd.

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  • Авторы: Melnikov I.A. (P.P. Shirshov Institute of Oceanology, Moscow, Russia), Kolosova L.G., Zhitina L.S.(M.V. Lomonosov Moscow State University, Moscow, Russia), Welch H.E. (Fresh Water Institute, Winnipeg, Canada)
  • Издание: Deep-Sea Research, 1 (49)
  • Год издания: 2002
  • Страницы: 1623-1649
  • Аннотация на английском языке: Salinity, concentrations of silicate (Si), phosphate (P), andchlorophyll a (chl a), andthe species composition of floral andfaunal communities were assessedin multi-year (MY) andfirst-year (FY) ice, and at the water-ice interface, during the SHEBA ice camp drift in the Canadian Basin of the Arctic Ocean, October 1997-October 1998. Mean integrated salinity values variedfrom 0.1 7 0.8% within the snow-ice boundary to 3.2 7 1.46% at the water-ice interface in the MY ice. Salinity of FY ice increasedwith increasing ice thickness, from 0.41 7 0.19% in October to 3.397 1.75% in March. We foundvery low concentrations of both Si andP in MY andFY ice in late fall (<0.01 mM), after the summer season of 1997. Mean integratedconcentration of nutrients increasedwith the freeze-up of ice, reaching maximum values in the summer of 1998. Ice algal biomass was dominated by diatoms in the MY and FY ice, with more pennate than centric species. Species of dinoflagellates and green algae were subdominant. Green algae, typically confined to the upper part of the ice, were distributed throughout the ice thickness. During summer, the brackish-water green alga Ulothrix implexa formedlong rope-like tufts attached to the hull of the icebreaker; development of this species has not previously been observedin the central Arctic Ocean. Biomass, cell abundance andchl a concentrations were high in the bottom sections of both MY and FY ice during the pre-freezing period, then decreased in winter and reached maximum values in spring andsummer. The total algal biomass showeda pattern similar to chl a dynamics, decreasing from 1.7 mg Cl_1 in October to values < 0.1 mg C l~ in winter. Algal carbon biomass andchl a concentration co-variedsignificantly in the FY ice (r2 = 0:79), but less so in the MY ice (r2 = 0:49). An unexpectedfeature with respect to sea ice invertebrates was the absolute absence of living interstitial fauna within the interior of MY and FY sea ice. In addition, the under-ice fauna was species-poor. Comparisons of SHEBA results with historical data showed that the physical-chemical characteristics of sea ice and the biological structure of ice communities found in this study were very different from conditions during the 1970s. It is likely that the changes resulted from increased melting of the arctic ice pack over the last two decades. © 2002 Publishedby Elsevier Science Ltd.
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