| dc.description.abstract |
Phaeocystis globosa is an important bloom-forming marine phytoplankton
species that often accumulates to large levels in temperate and tropical waters and has significant impacts on food webs and biogeochemical cycles.
It can form “giant” colonies that reach 3cm in diameter. Microscopic observations, colony elemental composition, and pigment composition were analyzed to assess the characteristics of colonies as a function of colony size.
Particulate organic carbon (POC) per unit surface area, colonial cell density,
and chlorophyll a per unit surface area all increased with colony size, in contrast to results from temperate waters. Cellular chl a averaged 0.85pg chl ·
cell−1. Colonies had both photosynthetic and protective pigments, with fucoxanthin being the dominant accessory pigment. Based on chl a and pigment
levels, it appears colonies were acclimated to relatively low irradiances, likely
due to their life cycle and the extremely turbulent environment in which they
grew. Mucous carbon ranged from 16.2% to 79.2% of the total POC, and
mucous carbon per unit surface area increased with colony size, suggesting
that the mucous envelope did not thin as the colony grew. Based on elemental
composition, nitrogen did not appear to limit growth, but phosphorus:carbon
ratios were similar to those of P-limited cultures. Giant colonies represent an
extreme response to the environment, but they do not appear to have greatly
different characteristics than other tropical strains. |
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