Carbon uptake and turnover rates of phytoplankton in Newfoundland coastal waters

Pauley, Kevin Eugene (1986) Carbon uptake and turnover rates of phytoplankton in Newfoundland coastal waters. Masters thesis, Memorial University of Newfoundland.

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Abstract

In situ enclosure experiments were completed during phytoplankton bloom and non-bloom conditions in coastal Newfoundland waters. Carbon uptake, pool size and turnover rates of various phytoplankton species and size components were studied using ¹⁴C track autoradiography and standard filtration techniques. Total POC was approximately 313 μg l⁻¹ during bloom conditions compared to 188 μg l⁻¹ in the non bloom enclosure. Approximately 76% of tho POC pool in the bloom enclosure was labelled over three days whereas only 32% was labelled in the non-bloom experiment. The measurement of ¹⁴C uptake yielded estimates of primary production for bloom and non-bloom conditions in the range of 100 μg C l⁻¹ d⁻¹, which were greater than maximum estimates recorded for the highly productive Grand Banks region (ca. 82 μg C l⁻¹ d⁻¹). The measurement of specific cellular carbon uptake over time revealed that, while carbon pool sizes of phytoplankters during bloom conditions agreed well with values found in literature, similar taxa associated with the non-bloom experiment had pools about one half the expected size. Diatoms were responsible for about 51% of the carbon uptake and phytoflagellate nanoplankters 16% during the the bloom. In contrast, nanoplankton accounted for 25% of the non-bloom uptake. The remaining uptake in both experiments could not be attributed to identifiable particulate sources. This suggests that energy flow to higher trophic levels may not be soley through a classical algar-grazer food chain during non-bloom conditions.

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