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The role of dissolved organic matter ( DOM ) quality in the growth enhancement of Alexandrium fundyense (Dinophyceae) in laboratory culture 1
Author(s) -
Cawley Kaelin M.,
Koerfer Verena,
McKnight Diane M.
Publication year - 2013
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/jpy.12063
Subject(s) - biology , algal bloom , dissolved organic carbon , organic matter , plankton , colored dissolved organic matter , algae , bloom , environmental chemistry , dinophyceae , phytoplankton , aquatic plant , botany , ecology , nutrient , chemistry , macrophyte
Several algal species responsible for harmful algal blooms ( HAB s), such as Alexandrium fundyense , 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 HAB s 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 A. fundyense . We found that a terrestrially derived HDOM , Suwannee River humic acid ( SRHA ), did enhance A. fundyense growth; however, a microbially derived HDOM , Pony Lake fulvic acid (PLFA) did not enhance growth. A. fundyense grows in association with bacteria in culture and we observed that bacterial cell densities were much lower in A. fundyense cultures than in bacteria‐only cultures, consistent with bacterial grazing by A. fundyense 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 A. fundyense 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 A. fundyense growth, and that the differential effect is not a result of an effect on the growth of associated bacteria.