Phytoplankton aggregate formation: observations of patterns and mechanisms of cell sticking and the significance of exopolymeric material

Thomas Kiørboe, Jorgen L. S. Hansen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Flocculation of 'sticky' phytoplankton cells into rapidly sinking aggregates has been invoked as a mechanism explaining mass sedimentation of phytoplankton blooms in the ocean. Phytoplankton stickiness, defined as the probability of adhesion upon collision, is one key factor determining the potential for aggregate formation. In the laboratory, we examined variation in stickiness in five species of diatoms and two species of flagellates grown in batch cultures. We also investigated the production of particulate mucus by phytoplankton cells and its role in aggregate formation, and we studied the effects of solute exudates on cell stickiness. Four of the five diatoms investigated were significantly sticky, while one diatom and both of the flagellates were not sticky. Stickiness varied considerably within species. In the diatom Skeletonema costatum, the typical but not entirely consistent pattern was that stickiness decreased with age of the batch cultures. We were otherwise unable to establish consistent relationships between cell stickiness and the growth stage of the algae, environmental concentrations of inorganic nutrients, and abundances of suspended and epiphytic bacteria. We showed that the diatom S. costatum at times excretes a solute substance that depresses flocculation. This may reduce cell losses from the euphotic zone during the growth phase due to flocculation and sedimentation. We demonstrated two different mechanisms of phytoplankton aggregate formation. In the diatom S. costatum, the cells are sticky in themselves, and coagulation depends on cell-cell sticking and does not involve mucus. Aggregates are composed solely of cells. Cells of the diatom Chaetoceros affinis, on the other hand, are not in themselves sticky. Transparent exopolymeric particles (TEP), produced by the diatom, cause the cells to aggregate and coagulation depends on TEP-cell rather than cell-cell sticking. Aggregates are formed of a mixture of mucus and cells. We found several species of diatoms and one flagellate species to produce copious amounts of TEP. TEP from some species (e.g. Coscinodiscus sp.) is sticky and may cause other, non-sticky particles to coagulate. This emphasizes the potential importance of diatom-derived particulate mucus for particle flocculation in the ocean.
Original languageEnglish
JournalJournal of Plankton Research
Volume15
Issue number9
Pages (from-to)993-1018
ISSN0142-7873
DOIs
Publication statusPublished - 1993

Cite this

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title = "Phytoplankton aggregate formation: observations of patterns and mechanisms of cell sticking and the significance of exopolymeric material",
abstract = "Flocculation of 'sticky' phytoplankton cells into rapidly sinking aggregates has been invoked as a mechanism explaining mass sedimentation of phytoplankton blooms in the ocean. Phytoplankton stickiness, defined as the probability of adhesion upon collision, is one key factor determining the potential for aggregate formation. In the laboratory, we examined variation in stickiness in five species of diatoms and two species of flagellates grown in batch cultures. We also investigated the production of particulate mucus by phytoplankton cells and its role in aggregate formation, and we studied the effects of solute exudates on cell stickiness. Four of the five diatoms investigated were significantly sticky, while one diatom and both of the flagellates were not sticky. Stickiness varied considerably within species. In the diatom Skeletonema costatum, the typical but not entirely consistent pattern was that stickiness decreased with age of the batch cultures. We were otherwise unable to establish consistent relationships between cell stickiness and the growth stage of the algae, environmental concentrations of inorganic nutrients, and abundances of suspended and epiphytic bacteria. We showed that the diatom S. costatum at times excretes a solute substance that depresses flocculation. This may reduce cell losses from the euphotic zone during the growth phase due to flocculation and sedimentation. We demonstrated two different mechanisms of phytoplankton aggregate formation. In the diatom S. costatum, the cells are sticky in themselves, and coagulation depends on cell-cell sticking and does not involve mucus. Aggregates are composed solely of cells. Cells of the diatom Chaetoceros affinis, on the other hand, are not in themselves sticky. Transparent exopolymeric particles (TEP), produced by the diatom, cause the cells to aggregate and coagulation depends on TEP-cell rather than cell-cell sticking. Aggregates are formed of a mixture of mucus and cells. We found several species of diatoms and one flagellate species to produce copious amounts of TEP. TEP from some species (e.g. Coscinodiscus sp.) is sticky and may cause other, non-sticky particles to coagulate. This emphasizes the potential importance of diatom-derived particulate mucus for particle flocculation in the ocean.",
author = "Thomas Ki{\o}rboe and Hansen, {Jorgen L. S.}",
year = "1993",
doi = "10.1093/plankt/15.9.993",
language = "English",
volume = "15",
pages = "993--1018",
journal = "Journal of Plankton Research",
issn = "0142-7873",
publisher = "Oxford University Press",
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}

Phytoplankton aggregate formation: observations of patterns and mechanisms of cell sticking and the significance of exopolymeric material. / Kiørboe, Thomas; Hansen, Jorgen L. S.

In: Journal of Plankton Research, Vol. 15, No. 9, 1993, p. 993-1018.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Phytoplankton aggregate formation: observations of patterns and mechanisms of cell sticking and the significance of exopolymeric material

AU - Kiørboe, Thomas

AU - Hansen, Jorgen L. S.

PY - 1993

Y1 - 1993

N2 - Flocculation of 'sticky' phytoplankton cells into rapidly sinking aggregates has been invoked as a mechanism explaining mass sedimentation of phytoplankton blooms in the ocean. Phytoplankton stickiness, defined as the probability of adhesion upon collision, is one key factor determining the potential for aggregate formation. In the laboratory, we examined variation in stickiness in five species of diatoms and two species of flagellates grown in batch cultures. We also investigated the production of particulate mucus by phytoplankton cells and its role in aggregate formation, and we studied the effects of solute exudates on cell stickiness. Four of the five diatoms investigated were significantly sticky, while one diatom and both of the flagellates were not sticky. Stickiness varied considerably within species. In the diatom Skeletonema costatum, the typical but not entirely consistent pattern was that stickiness decreased with age of the batch cultures. We were otherwise unable to establish consistent relationships between cell stickiness and the growth stage of the algae, environmental concentrations of inorganic nutrients, and abundances of suspended and epiphytic bacteria. We showed that the diatom S. costatum at times excretes a solute substance that depresses flocculation. This may reduce cell losses from the euphotic zone during the growth phase due to flocculation and sedimentation. We demonstrated two different mechanisms of phytoplankton aggregate formation. In the diatom S. costatum, the cells are sticky in themselves, and coagulation depends on cell-cell sticking and does not involve mucus. Aggregates are composed solely of cells. Cells of the diatom Chaetoceros affinis, on the other hand, are not in themselves sticky. Transparent exopolymeric particles (TEP), produced by the diatom, cause the cells to aggregate and coagulation depends on TEP-cell rather than cell-cell sticking. Aggregates are formed of a mixture of mucus and cells. We found several species of diatoms and one flagellate species to produce copious amounts of TEP. TEP from some species (e.g. Coscinodiscus sp.) is sticky and may cause other, non-sticky particles to coagulate. This emphasizes the potential importance of diatom-derived particulate mucus for particle flocculation in the ocean.

AB - Flocculation of 'sticky' phytoplankton cells into rapidly sinking aggregates has been invoked as a mechanism explaining mass sedimentation of phytoplankton blooms in the ocean. Phytoplankton stickiness, defined as the probability of adhesion upon collision, is one key factor determining the potential for aggregate formation. In the laboratory, we examined variation in stickiness in five species of diatoms and two species of flagellates grown in batch cultures. We also investigated the production of particulate mucus by phytoplankton cells and its role in aggregate formation, and we studied the effects of solute exudates on cell stickiness. Four of the five diatoms investigated were significantly sticky, while one diatom and both of the flagellates were not sticky. Stickiness varied considerably within species. In the diatom Skeletonema costatum, the typical but not entirely consistent pattern was that stickiness decreased with age of the batch cultures. We were otherwise unable to establish consistent relationships between cell stickiness and the growth stage of the algae, environmental concentrations of inorganic nutrients, and abundances of suspended and epiphytic bacteria. We showed that the diatom S. costatum at times excretes a solute substance that depresses flocculation. This may reduce cell losses from the euphotic zone during the growth phase due to flocculation and sedimentation. We demonstrated two different mechanisms of phytoplankton aggregate formation. In the diatom S. costatum, the cells are sticky in themselves, and coagulation depends on cell-cell sticking and does not involve mucus. Aggregates are composed solely of cells. Cells of the diatom Chaetoceros affinis, on the other hand, are not in themselves sticky. Transparent exopolymeric particles (TEP), produced by the diatom, cause the cells to aggregate and coagulation depends on TEP-cell rather than cell-cell sticking. Aggregates are formed of a mixture of mucus and cells. We found several species of diatoms and one flagellate species to produce copious amounts of TEP. TEP from some species (e.g. Coscinodiscus sp.) is sticky and may cause other, non-sticky particles to coagulate. This emphasizes the potential importance of diatom-derived particulate mucus for particle flocculation in the ocean.

U2 - 10.1093/plankt/15.9.993

DO - 10.1093/plankt/15.9.993

M3 - Journal article

VL - 15

SP - 993

EP - 1018

JO - Journal of Plankton Research

JF - Journal of Plankton Research

SN - 0142-7873

IS - 9

ER -