Interannual Differences in Nutrient Dynamics During a Brown Tide Bloom (<i>Aureococcus anophagefferens</i>) and the Interaction of <i>A. anophagefferens</i> with Heterotrophic Bacteria

<p>Blooms of <em>Aureococcus anophagefferens</em> (Brown Tides) in Chincoteague Bay were observed over a six-year period (2002–2007) during which interannual differences in nitrogen and carbon uptake and concentrations of dissolved constituents were compared at two sites, one in Maryland and the other in Virginia. Overall, I observed an increase in bloom intensity and duration over time. No single nitrogen compound was responsible for fueling blooms. Instead, <em>A. anophagefferens</em> demonstrated the ability to use a wide range of nitrogen compounds to meet its nutritional demands. Results show that NO₃-, NH₄+, urea, and DFAA were taken up simultaneously during blooms and the dominant source of N varied between years. Although photosynthesis was the dominant form of carbon acquisition, organic carbon uptake contributed up to 30% of the total carbon uptake.</p> <p>The contribution of <em>A. anophagefferens</em> and heterotrophic bacteria to total carbon and nitrogen uptake rates was also examined by using flow cytometry. Results demonstrated that it is possible to distinguish and quantify taxon-specific uptake of C and N by <em>A. anophagefferens</em> versus heterotrophic bacteria during incubations of natural assemblages using stable isotopes as tracers coupled with flow cytometry. Bacteria and <em>A. anophagefferens</em> cell-specific uptake rates reported here confirm that <em>A. anophagefferens</em> uses a wide range of N sources during blooms including NO₃-, NH₄+, urea, and DFAA-N and it, and not bacteria, are the dominant consumers of these resources in the environment. This finding has important implications for bacterial productivity studies that assume bacteria are the primary consumers of the amino acids</p> <p>C and N uptake was also examined over many diet light cycles to determine if dark C and N uptake augments photosynthetic C uptake and DIN uptake by <em>A. anophagefferens</em> during the day. Results demonstrated that <em>A. anophagefferens</em> actively takes up both organic C and organic and inorganic N during the day and night. This finding is critical for understanding the N and C nutrition of this organism because current dogma is that C uptake by photoautotrophs is limited to daylight hours and N uptake at night is low and limited to particular N compounds and environmental conditions.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ocean & Earth Sciences

Year dc:date.available

2010

Author dc:creator

• Boneillo, George Eric

Contributors dc:contributor

• Margaret R. Mulholland
• Fred C. Dobbs
• Andrew S. Gordon
• Michael W. Lomas

• Aureococcus anophagefferens
• Bacteria
• Blooms
• Brown tide
• Nutrients
• Oceanography

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Identifier

9781124483054

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:oeas_etds-1029