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Ecological controls on estuarine pla...

Chan, Francis.

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Ecological controls on estuarine planktonic nitrogen-fixation: The roles of grazing and cross -ecosystem patterns in phytoplankton mortality.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Ecological controls on estuarine planktonic nitrogen-fixation: The roles of grazing and cross -ecosystem patterns in phytoplankton mortality./
Author:	Chan, Francis.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2001,
Description:	303 p.
Notes:	Source: Dissertations Abstracts International, Volume: 63-05, Section: B.
Contained By:	Dissertations Abstracts International63-05B.
Subject:	Ecology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3011242
ISBN:	9780493206097

Ecological controls on estuarine planktonic nitrogen-fixation: The roles of grazing and cross -ecosystem patterns in phytoplankton mortality.
Chan, Francis.

Ecological controls on estuarine planktonic nitrogen-fixation: The roles of grazing and cross -ecosystem patterns in phytoplankton mortality. - Ann Arbor : ProQuest Dissertations & Theses, 2001 - 303 p.

Source: Dissertations Abstracts International, Volume: 63-05, Section: B.

Thesis (Ph.D.)--Cornell University, 2001.

This item must not be sold to any third party vendors.

The distribution and abundance of nitrogen (N)-fixing organisms is central to the persistence or alleviation of N-limitation in ecosystems. In many freshwater lakes, blooms of planktonic, heterocystic, N-fixing cyanobacteria are a common response to transient shortages of N. In surprising contrast, heterocystic cyanobacteria are largely absent from the water columns of estuaries, even where N strongly limits the rate of net primary production. Estuarine heterocystic cyanobacteria must thus face unique constraints relative to their counterparts in freshwaters and to all other estuarine phytoplankton taxa that are successful in forming seasonal blooms. This dissertation examines the ecological mechanisms that give rise to the scarcity of planktonic N-fixation in estuaries. In estuaries, trace-element limitation specific to N-fixers has been proposed to limit the growth of heterocystic cyanobacteria and thereby increase their vulnerability to suppression by herbivore consumers. In particular, reductions in colonial filament size by consumers are proposed to suppress the ability of heterocystic cyanobacteria to fix N and form blooms that are of significance to the N-economies of estuaries. In estuarine mesocosm and zooplankton grazing experiments, zooplankton consumers strongly and disproportionately inhibited the growth of heterocystic cyanobacteria in seawater. This sensitivity stemmed from size-structure dependent growth in heterocystic cyanobacteria, where reductions in filament colony size by grazers limited the ability of heterocystic cyanobacteria to produce heterocysts and fix N. Size-structure dependent growth was also clearly evident in in situ populations of heterocystic cyanobacteria in freshwater ponds. Temporally detailed sampling indicated that heterocystic cyanobacteria initially recruit to the water column at low densities as short and poorly heterocysted filaments. Rapid growth and bloom formation was possible only after cyanobacterial populations grew into long filaments that supported the development of heterocysts and active N-fixation. A comparative synthesis of phytoplankton biomass turnover rates further indicated that estuarine phytoplankton communities are subject to biomass-specific mortality rates that are ca. 3-fold higher than those experienced by their counterparts in freshwaters. The exclusion of heterocystic cyanobacteria from estuarine phytoplankton communities is likely to reflect the interactive effects of trace-element limitation, size-structure dependent growth, and the effects of consumer controls on estuarine N-fixer populations and phytoplankton community structures.

ISBN: 9780493206097Subjects--Topical Terms:

516476
Ecology.
Subjects--Index Terms:

Cross-ecosystem patterns

Ecological controls on estuarine planktonic nitrogen-fixation: The roles of grazing and cross -ecosystem patterns in phytoplankton mortality.
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245 1 0 $a Ecological controls on estuarine planktonic nitrogen-fixation: The roles of grazing and cross -ecosystem patterns in phytoplankton mortality.
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300 $a 303 p.
500 $a Source: Dissertations Abstracts International, Volume: 63-05, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Howarth, Robert W.;Pace, Michael L.
502 $a Thesis (Ph.D.)--Cornell University, 2001.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a The distribution and abundance of nitrogen (N)-fixing organisms is central to the persistence or alleviation of N-limitation in ecosystems. In many freshwater lakes, blooms of planktonic, heterocystic, N-fixing cyanobacteria are a common response to transient shortages of N. In surprising contrast, heterocystic cyanobacteria are largely absent from the water columns of estuaries, even where N strongly limits the rate of net primary production. Estuarine heterocystic cyanobacteria must thus face unique constraints relative to their counterparts in freshwaters and to all other estuarine phytoplankton taxa that are successful in forming seasonal blooms. This dissertation examines the ecological mechanisms that give rise to the scarcity of planktonic N-fixation in estuaries. In estuaries, trace-element limitation specific to N-fixers has been proposed to limit the growth of heterocystic cyanobacteria and thereby increase their vulnerability to suppression by herbivore consumers. In particular, reductions in colonial filament size by consumers are proposed to suppress the ability of heterocystic cyanobacteria to fix N and form blooms that are of significance to the N-economies of estuaries. In estuarine mesocosm and zooplankton grazing experiments, zooplankton consumers strongly and disproportionately inhibited the growth of heterocystic cyanobacteria in seawater. This sensitivity stemmed from size-structure dependent growth in heterocystic cyanobacteria, where reductions in filament colony size by grazers limited the ability of heterocystic cyanobacteria to produce heterocysts and fix N. Size-structure dependent growth was also clearly evident in in situ populations of heterocystic cyanobacteria in freshwater ponds. Temporally detailed sampling indicated that heterocystic cyanobacteria initially recruit to the water column at low densities as short and poorly heterocysted filaments. Rapid growth and bloom formation was possible only after cyanobacterial populations grew into long filaments that supported the development of heterocysts and active N-fixation. A comparative synthesis of phytoplankton biomass turnover rates further indicated that estuarine phytoplankton communities are subject to biomass-specific mortality rates that are ca. 3-fold higher than those experienced by their counterparts in freshwaters. The exclusion of heterocystic cyanobacteria from estuarine phytoplankton communities is likely to reflect the interactive effects of trace-element limitation, size-structure dependent growth, and the effects of consumer controls on estuarine N-fixer populations and phytoplankton community structures.
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650 4 $a Ecology. $3 516476
650 4 $a Biogeochemistry. $3 545717
653 $a Cross-ecosystem patterns
653 $a Estuarine
653 $a Grazing
653 $a Nitrogen fixation
653 $a Phytoplankton mortality
653 $a Planktonic
690 $a 0329
690 $a 0425
710 2 $a Cornell University. $3 530586
773 0 $t Dissertations Abstracts International $g 63-05B.
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791 $a Ph.D.
792 $a 2001
793 $a English
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