Assessing Phytoplankton and Bacterioplankton Production During Early Spring in Lake Erken, Sweden

AUTOR(ES)
RESUMO

The spring development of both phytoplankton and bacterioplankton was investigated between 18 April and 7 May 1983 in mesotrophic Lake Erken, Sweden. By using the lake as a batch culture, our aim was to estimate, via different methods, the production of phytoplankton and bacterioplankton in the lake and to compare these production estimates with the actual increase in phytoplankton and bacterioplankton biomass. The average water temperature was 3.5°C. Of the phytoplankton biomass, >90% was the diatom Stephanodiscus hantzchii var. pusillus, by the peak of the bloom. The 14C and O2 methods of estimating primary production gave equivalent results (r = 0.999) with a photosynthetic quotient of 1.63. The theoretical photosynthetic quotient predicted from the C/NO3 N assimilation ratio was 1.57. The total integrated incorporation of [14C]bicarbonate into particulate material (>1 μm) was similar to the increase in phytoplankton carbon determined from cell counts. Bacterioplankton increased from 0.5 × 109 to 1.52 × 109 cells liter−1 (∼0.5 μg of C liter−1 day−1). Estimates of bacterioplankton production from rates of [3H]thymidine incorporation were ca. 1.2 to 1.7 μg of C liter−1 day−1. Bacterial respiration, measured by a high-precision Winkler technique, was estimated as 4.8 μg of C liter−1 day−1, indicating a bacterial growth yield of 25%. The bulk of the bacterioplankton production was accounted for by algal extracellular products. Gross bacterioplankton production (production plus respiration) was 20% of gross primary production, per square meter of surface area. We found no indication that bacterioplankton production was underestimated by the [3H]thymidine incorporation method.

ACESSO AO ARTIGO

Documentos Relacionados