The role of dissolved organic matter (DOM) quality in the growth enhancement of Alexandrium fundyense (Dinophyceae) in laboratory culture1. Issue 3 (8th April 2013)

• Record Type: Journal Article
• Authors: Cawley, Kaelin M.; Koerfer, Verena; McKnight, Diane M.; Raven, J.
• Is Part Of: Journal of phycology. Volume 49:Issue 3(2013:Jun.)
• Page Start: 546
• Page End: 554
• Publication Date: 2013-04-08
• Subjects: Algae -- Periodicals; 579.8
• DOI: 10.1111/jpy.12063
• Languages: English
• ISSNs: 0022-3646

Abstract

<abstract abstract-type="main" id="jpy12063-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Several algal species responsible for harmful algal blooms (HABs), such as <italic>Alexandrium fundyense</italic>, are mixotrophic under certain environmental conditions. The ability to switch between photosynthetic and heterotrophic modes of growth may play a role in the development of HABs in coastal regions. We examined the influence of humic dissolved organic matter (HDOM) derived from terrestrial (plant/soil) and microbial sources on the growth of <italic>A. fundyense</italic>. We found that a terrestrially derived HDOM, Suwannee River humic acid (SRHA), did enhance <italic>A. fundyense</italic> growth; however, a microbially derived HDOM, Pony Lake fulvic acid (PLFA) did not enhance growth. <italic>A. fundyense</italic> grows in association with bacteria in culture and we observed that bacterial cell densities were much lower in <italic>A. fundyense</italic> cultures than in bacteria‐only cultures, consistent with bacterial grazing by <italic>A. fundyense</italic> in culture. In bacteria‐only cultures with added algal exudates (EX), the addition of PLFA and SRHA resulted in a slight increase in bacterial cell density compared to cultures without HDOM added. Changes over time in the chemical quality of the HDOM in the <italic>A. fundyense</italic> cultures reflected contributions of microbially derived material with similar characteristics as the PLFA. Overall, these results suggest that the chemical differences between SRHA and PLFA are responsible for the greater effect of SRHA on <italic>A. fundyense</italic> growth, and that the differential effect is not a result of an effect on the growth of associated bacteria.</p> </abstract>