Role of the chloroplasts in the predatory dinoflagellate Karlodinium armiger

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 549:41-54 (2016) - DOI: https://doi.org/10.3354/meps11682 Role of the chloroplasts in the predatory dinoflagellate Karlodinium armiger Terje Berge*, Per Juel Hansen Centre for Ocean Life, Marine Biological Section, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark *Corresponding author: tberge@bio.ku.dk ABSTRACT: Karlodinium armiger is a phagotrophic dinoflagellate that synthesizes several small chloroplasts of haptophyte origin. It depends on light, but it grows very poorly in standard nutrient growth media (f/2) without food. When fed prey in the light, growth rates increase dramatically (μ = 0.65 d-1), suggesting that it relies heavily on phagotrophic nutrition. To explore the reasons for this phenomenon and the role of the plastids for the growth of K. armiger, we measured C14 fixation rates, chl a content and growth rates as a function of irradiance in short- and long-term prey-starved cultures. In starved cultures, rates of photosynthesis were relatively high and increased as a function of irradiance, even though growth rates remained low. In fed cultures, both ingestion and growth rates of K. armiger increased as a function of irradiance in a saturating manner. Cellular chl a contents and photosynthetic rates were ~40 and ~70% lower, respectively, in long-term compared to short-term starved phototrophic cells at irradiances of 70 to 250 µmol photons m-2 s-1. Carbon fixation was important for achieving high mixotrophic growth rates, especially in prey-limited conditions. However, under prey-saturated conditions, K. armiger seems to obtain most of its carbon through phagotrophy. Our data suggest that feeding stimulates the photosynthetic machinery under nutrient limitation, and that the poor phototrophic growth capacity of K. armiger in the absence of prey seems to be due to a lack or a very poor ability to take up essential inorganic nutrients. KEY WORDS: Mixotrophy · Photosynthesis · Phytoplankton · Growth · Ingestion · Dinoflagellates · Harmful algae Full text in pdf format PreviousNextCite this article as: Berge T, Hansen PJ (2016) Role of the chloroplasts in the predatory dinoflagellate Karlodinium armiger . Mar Ecol Prog Ser 549:41-54. https://doi.org/10.3354/meps11682 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 549. Online publication date: May 10, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.