Dynamics in carbohydrate composition of Phaeocystis pouchetii colonies during spring blooms in mesocosms
The colony-forming microalgae Phaeocystis produces two major pools of carbohydrates: in mucopolysaccharides in the colony matrix and intracellular storage glucan. Both have different functions and separate degradation pathways in the ecosystem, so a partial precipitation method was developed to dist...
| Published in: | Journal of Sea Research |
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| Main Authors: | , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2006
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| Subjects: | |
| Online Access: | https://hdl.handle.net/11370/c1714a57-1231-4693-be29-de53c8b6cf6b https://research.rug.nl/en/publications/c1714a57-1231-4693-be29-de53c8b6cf6b https://doi.org/10.1016/j.seares.2005.10.005 |
| Summary: | The colony-forming microalgae Phaeocystis produces two major pools of carbohydrates: in mucopolysaccharides in the colony matrix and intracellular storage glucan. Both have different functions and separate degradation pathways in the ecosystem, so a partial precipitation method was developed to distinguish the dynamics of the two pools. Changes in concentration in response to variation in nutrients and irradiance were followed during a spring bloom of Phaeocystis pouchetii colonies in mesocosms near Bergen, Norway. Upon nutrient limitation, the carbohydrate to carbon ratio of the colonies increased from 15% during the growth phase, to more than 50% during the decline phase. During the growth phase of the bloom, the carbohydrate concentration and composition were influenced by irradiance: glucan concentrations showed strong diel dynamics and increased with higher light levels, whereas mucopolysaccharide concentrations were unaffected. During the exponential growth phase, glucan contributed 6-11% to P. pouchetii carbon, depending on the time of the day. During the decline of the bloom, the glucan contribution increased up to 60%. We provide further evidence for the concept that the Phaeocystis colony matrix is built with a relatively small but constant amount of carbohydrates, compared to the large quantities of glucan produced during Phacocystis spring blooms. Since a major part of Phaeocystis primary production is recycled in the water column by bacteria, this vast glucan injection is a potential determinant of the magnitude and composition of the microbial community following a bloom. (c) 2005 Elsevier B.V. All rights reserved. |
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