Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica
In the Ross Sea, there are two major phytoplankton functional groups: diatoms and prymnesiophytes (dominated by Phaeocystis antarctica). Phaeocystis antarctica often occurs in colonial form, but also as solitary cells, and the two forms have distinct ecological roles. A comparison of the growth char...
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fthighwire:oai:open-archive.highwire.org:plankt:31/7/701 2023-05-15T14:03:57+02:00 Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica Shields, Amy R. Smith, Walker O. 2009-07-01 00:00:00.0 text/html http://plankt.oxfordjournals.org/cgi/content/short/31/7/701 https://doi.org/10.1093/plankt/fbp022 en eng Oxford University Press http://plankt.oxfordjournals.org/cgi/content/short/31/7/701 http://dx.doi.org/10.1093/plankt/fbp022 Copyright (C) 2009, Oxford University Press FEATURED ARTICLE TEXT 2009 fthighwire https://doi.org/10.1093/plankt/fbp022 2013-05-27T04:54:37Z In the Ross Sea, there are two major phytoplankton functional groups: diatoms and prymnesiophytes (dominated by Phaeocystis antarctica). Phaeocystis antarctica often occurs in colonial form, but also as solitary cells, and the two forms have distinct ecological roles. A comparison of the growth characteristics of solitary and colonial forms of Phaeocystis sp. is essential to understanding the differential impact each has on biogeochemical and ecological processes, and to allow parameterization of each form in numerical models. We measured the biomass and photosynthetic responses of two size fractions (>20 and <20 µm), representing colonies and solitary cells, at locations dominated by P. antarctica to assess the relative photosynthetic potential of the two forms. While the relative contribution of each form to total P. antarctica biomass differed among years, there were no significant differences between maximum photosynthetic rates of colonial and solitary forms within years. Substantial interannual variations in biomass and maximum photosynthetic rates normalized to chlorophyll a (P<f> m B</f>) and initial light-limited rates of photosynthesis (α) were observed among years for the colonial fractions; however, interannual variations in maximum rates of photosynthesis or α of solitary cells were not observed. A laboratory experiment with P. antarctica, together with field data, showed that growth stage of colonies strongly affected the maximum photosynthetic rates. Under nutrient-replete conditions and exponential growth, colonial cells had higher maximum photosynthetic rates than solitary cells, but as growth rate declined and senescence began, the solitary cells' rates became greater. This may be a reason for the high abundance of colonies that is often found in the Ross Sea during austral spring. Our results suggest that photosynthetic rates may influence the composition of the morphotypes of Phaeocystis, but do not appear to be the sole factor in regulating this critical biological variable. Text Antarc* Antarctica Ross Sea HighWire Press (Stanford University) Austral Ross Sea Journal of Plankton Research 31 7 701 712 |
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HighWire Press (Stanford University) |
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English |
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FEATURED ARTICLE |
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FEATURED ARTICLE Shields, Amy R. Smith, Walker O. Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica |
topic_facet |
FEATURED ARTICLE |
description |
In the Ross Sea, there are two major phytoplankton functional groups: diatoms and prymnesiophytes (dominated by Phaeocystis antarctica). Phaeocystis antarctica often occurs in colonial form, but also as solitary cells, and the two forms have distinct ecological roles. A comparison of the growth characteristics of solitary and colonial forms of Phaeocystis sp. is essential to understanding the differential impact each has on biogeochemical and ecological processes, and to allow parameterization of each form in numerical models. We measured the biomass and photosynthetic responses of two size fractions (>20 and <20 µm), representing colonies and solitary cells, at locations dominated by P. antarctica to assess the relative photosynthetic potential of the two forms. While the relative contribution of each form to total P. antarctica biomass differed among years, there were no significant differences between maximum photosynthetic rates of colonial and solitary forms within years. Substantial interannual variations in biomass and maximum photosynthetic rates normalized to chlorophyll a (P<f> m B</f>) and initial light-limited rates of photosynthesis (α) were observed among years for the colonial fractions; however, interannual variations in maximum rates of photosynthesis or α of solitary cells were not observed. A laboratory experiment with P. antarctica, together with field data, showed that growth stage of colonies strongly affected the maximum photosynthetic rates. Under nutrient-replete conditions and exponential growth, colonial cells had higher maximum photosynthetic rates than solitary cells, but as growth rate declined and senescence began, the solitary cells' rates became greater. This may be a reason for the high abundance of colonies that is often found in the Ross Sea during austral spring. Our results suggest that photosynthetic rates may influence the composition of the morphotypes of Phaeocystis, but do not appear to be the sole factor in regulating this critical biological variable. |
format |
Text |
author |
Shields, Amy R. Smith, Walker O. |
author_facet |
Shields, Amy R. Smith, Walker O. |
author_sort |
Shields, Amy R. |
title |
Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica |
title_short |
Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica |
title_full |
Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica |
title_fullStr |
Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica |
title_full_unstemmed |
Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica |
title_sort |
size-fractionated photosynthesis/irradiance relationships during phaeocystis antarctica-dominated blooms in the ross sea, antarctica |
publisher |
Oxford University Press |
publishDate |
2009 |
url |
http://plankt.oxfordjournals.org/cgi/content/short/31/7/701 https://doi.org/10.1093/plankt/fbp022 |
geographic |
Austral Ross Sea |
geographic_facet |
Austral Ross Sea |
genre |
Antarc* Antarctica Ross Sea |
genre_facet |
Antarc* Antarctica Ross Sea |
op_relation |
http://plankt.oxfordjournals.org/cgi/content/short/31/7/701 http://dx.doi.org/10.1093/plankt/fbp022 |
op_rights |
Copyright (C) 2009, Oxford University Press |
op_doi |
https://doi.org/10.1093/plankt/fbp022 |
container_title |
Journal of Plankton Research |
container_volume |
31 |
container_issue |
7 |
container_start_page |
701 |
op_container_end_page |
712 |
_version_ |
1766274858195353600 |