Dynamics of phyto- and bacterioplankton in a high Arctic lake on Franz Joseph Land archipelago

Abstract

Pelagic food web processes with focus on phyto-and bacterioplankton dynamics were followed in a high Arctic lake on Ziegler Island, Franz Joseph Land archipelago, during July and August 1996. The oligotrophlc, permanently ice-covered lake is characterized by a rather short pelagic food web with rotifers representing the highest trophic level. Phytoplankton biomass and net primary production averaging 1.8 pg chl a 1-' and 22 pg C 1-' d-', respectively, decreased dunng the investigation period. Photosynthetic extracellular release (P,,) corrected for bacterial uptake was high and contributed between 31 % (July) and 96% (August) of total primary production. The abundance of bacteria (9.3 to 17.3 X 10' ml-l) and flagellates (7.8 to 17.3 X 10' ml-l) varied within a narrow range. Bacterioplankton production ranging from 1.2 to 3.9 pg C 1-' d-' and bacterial growth rates (0.1 to 0.3 d-') increased with increasing % P,,, indicating that algal exudates are the major carbon source for bacterioplankton. Bacterial carbon demand (assuming a 50% growth efficiency) amounted to 19% of gross pelagic primary production (P,,,, + P,,) and 31 % of P,, during the investigation period. Evidence was found that bacterioplankton metabolism responds quickly to slight increases in temperature (1.2 to 2.0°C) with increased growth. Overall, production rates of phyto-and bacterioplankton in this high Arctic lake are simdar to other Arctic lakes studied thus far, and the food web structure is even simpler than in most lakes at similar latitudes.

Effect of solar radiation on photosynthetic extracellular carbon release and its microbial utilization in alpine and Arctic lakes

“…A similar conclusion was reached by Reche et al (1996) for another high-mountain lake and by Panzenböck et al (2000) for a high Arctic lake. In most studies, however, the amount of PER was insufficient to meet the BCD (Chrzanowski & Hubbard 1982, Cole et al 1982, Sondergaard et al 1985, Baines & Pace 1991, Descy et al 2002.…”

“…The % net PER obtained in GKS is at the upper end of values reported for oligotrophic lakes (e.g. Nalewajko & Schindler 1976, Tilzer & Horne 1979, Cole et al 1982 but similar to values estimated in oligotrophic mountain lakes (Reche et al 1996, Camarero et al 1999) and in Antarctic and Arctic lakes (Parker et al 1977, Panzenböck et al 2000.…”

“…The values of the biological parameters observed in LI and NYA are typical for Arctic lakes, whereas the primary production rates in LI range among the highest values reported for lakes of similar latitude (Markager et al 1999, Hobbie et al 2000, Panzenböck et al 2000, Ellis-Evans et al 2001, Laybourn-Parry & Marshall 2003, even using only the particulate primary production for comparison, since in most of these studies PER was not included in the primary production measurements. In the present study, carbon fixation (P tot ) would be underestimated by 21% in LI and by 51% in NYA if only the particulate fractions were considered.…”

Rates of dissolved organic carbon production and bacterial activity in the eastern North Atlantic Subtropical Gyre during summer

“…Although several studies focussing on the relationship between phytoplankton and bacterioplankton have shown a close coupling between the release of DOC and BP rates (e.g. Lancelot & Billen 1984, Panzenböck et al 2000, Morán et al 2001, other studies have found that the in situ production of phytoplankton-derived DOC would be insufficient to support the heterotrophic population (e.g. Williams & Yentsch 1976, Bode et al 2001.…”

Entry approach into pristine ice‐sealed lakes—Lake Vida, East Antarctica, a model ecosystem

“…Thereafter, only minor modifications of practices used in open-water lakes are usually required. Perennial ice-covered lakes have been studied and characterized in this manner in the Antarctic (Bird et al 1991;Priscu et al 1999;Wharton et al 1989) and the Arctic (Barnes 1960;Panzenbock et al 2000). Sampling practices in perennially ice-covered lakes have proceeded as they have in open-water lakes with little attention to instrument-associated "forward" contamination.…”