Diatom assemblages promote ice formation in large lakes

We present evidence for the directed formation of ice by planktonic communities dominated by filamentous diatoms sampled from the ice-covered Laurentian Great Lakes. We hypothesize that ice formation promotes attachment of these non-motile phytoplankton to overlying ice, thereby maintaining a favora...

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Bibliographic Details
Published in:	The ISME Journal Vol. 7; no. 8; pp. 1632 - 1640
Main Authors:	D'souza, N A, Kawarasaki, Y, Gantz, J D, Lee, R E, Beall, B F N, Shtarkman, Y M, Koçer, Z A, Rogers, S O, Wildschutte, H, Bullerjahn, G S, McKay, R M L
Format:	Journal Article
Language:	English
Published:	London Nature Publishing Group UK 01-08-2013 Nature Publishing Group
Subjects:	631/158/2459 631/326/2565/855 Aquatic ecosystems Bacillariophyceae Bacteria Bacteria - classification Bacteria - isolation & purification Bacteria - ultrastructure Biomedical and Life Sciences Crystallization Diatoms - microbiology Diatoms - physiology Diatoms - ultrastructure DNA, Ribosomal - genetics Ecology Ecosystem Evolutionary Biology Frazil ice Freezing Freshwater High temperature Ice Ice cover Ice formation Lake ice Lakes Life cycles Life Sciences Microbial Ecology Microbial Genetics and Genomics Microbiology Microscopy, Electron, Scanning Molecular Sequence Data Nucleation Organic carbon Original original-article Phytoplankton Phytoplankton - microbiology Phytoplankton - physiology Temperature Winter North America, Erie L North America, Great Lakes diatoms ice nucleation lake
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Summary:	We present evidence for the directed formation of ice by planktonic communities dominated by filamentous diatoms sampled from the ice-covered Laurentian Great Lakes. We hypothesize that ice formation promotes attachment of these non-motile phytoplankton to overlying ice, thereby maintaining a favorable position for the diatoms in the photic zone. However, it is unclear whether the diatoms themselves are responsible for ice nucleation. Scanning electron microscopy revealed associations of bacterial epiphytes with the dominant diatoms of the phytoplankton assemblage, and bacteria isolated from the phytoplankton showed elevated temperatures of crystallization ( T c ) as high as −3 °C. Ice nucleation-active bacteria were identified as belonging to the genus Pseudomonas , but we could not demonstrate that they were sufficiently abundant to incite the observed freezing. Regardless of the source of ice nucleation activity, the resulting production of frazil ice may provide a means for the diatoms to be recruited to the overlying lake ice, thereby increasing their fitness. Bacterial epiphytes are likewise expected to benefit from their association with the diatoms as recipients of organic carbon excreted by their hosts. This novel mechanism illuminates a previously undescribed stage of the life cycle of the meroplanktonic diatoms that bloom in Lake Erie and other Great Lakes during winter and offers a model relevant to aquatic ecosystems having seasonal ice cover around the world.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Current Address: Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA. Current Address: Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.
ISSN:	1751-7362 1751-7370
DOI:	10.1038/ismej.2013.49