Feeding, growth and metabolism of the marine heterotrophic dinoflagellate Gyrodinium dominans

Abstract

Rates of grazing, growth, and respiration were studied in the heterotrophic dinoflagellate Gyrodinium dominans experiencing a single pulse of prey. Additionally, rates of grazing and growth were compared to those of G. dominans growing with constant concentrations of prey. The maximal specific growth rates of G. dominans with a single pulse of prey were similar to those observed when G. dominans was acclimated to constant levels of prey. Thus, our results support the hypothesis that the growth of G. dominans responds quickly to changes in the abundance of prey. Moreover, growth rates were negative when concentrations of prey were low; this would suggest that G. dominans is adapted to eutrophic conditions. Respiration rates were higher than growth rates when G. dominans was fed a single pulse of prey, and we hypothesize that the ability to respond numerically to a changing abundance of prey may inflict high metabolic costs. Gross growth efficiencies (GGEs), determined for G. dominans in both food availability conditions, were within the range of values reported for other heterotrophic protozoans, and while GGE decreased when concentrations of food were high in organisms fed a single pulse of food, the opposite was observed in organisms acclimatized to a constant level of food. KEY WORDS: Heterotrophic dinoflagellate · Grazing · Growth · Respiration · GGE Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 65: [65][66][67][68][69][70][71][72][73] 2011 sure. However, matter is lost at varying rates from each trophic level as it is transported up through the food web. Part of the ingested and assimilated matter is used for energy production in respiration before it is transported to the next level. The result is a balance between GGE and respiration, which controls the transport of energy to the upper food web. While the importance of GGE is obvious, the significance of respiration may be more obscure. As in metazoan grazers such as copepods , respiration rates may vary with the food conditions encountered, and they may, as a result, account for considerably varying portions of the total energy budget.Information about the ecological role of heterotrophic dinoflagellates is now increasing (e.g. Hansen 1991, 1992, Strom 1991, Nakamura et al. 1992, Jacobson & Anderson 1993, Strom & Buskey 1993, Verity et al. 1993, and some literature exists on their grazing and growth (e.g. Strom 1991, Hansen 1992, Jeong et al. 2005. However, knowledge about the underlying energetics of trophic transport by dinoflagellates is still sparse in comparison to our knowledge of ciliates (e.g. Verity 1985, Bernard & Rassoulzadegan 1990, Verity 1991. For instance, while Verity (1985) studied grazing, growth, excretion, and respiration in 2 tintinnid ciliate species, studies on Gyrodinium covered grazing and growth rates but unfortunately did not include respiration rates (Hansen 1992, Nakamura et al. 1992, 1995.In the present study, we measured grazing, growth, and respiration rates in ...

Adaptations to feast and famine in different strains of the marine heterotrophic dinoflagellates Gyrodinium dominans and Oxyrrhis marina

“…As reported by Schmoker et al (2011), we also observed a drop in ingestion rates of GYR at high prey concentrations. This may indicate that this species does not thrive well in eutrophic conditions, in contrast to OXY, which keeps feeding at maximum rates even at very high prey concentrations.…”

“…The rates found in this study fall within those reported by Goldman et al (1989), Roberts et al (2011), and Nakamura et al (1995) for OXY feeding on a variety of prey, and for overall heterotrophic dinoflagellates summarized by Jeong et al (2010). However, they are lower than the specific values presented by Schmoker et al (2011) and the per cell rates shown in Hantzsche & Boersma (2010) for GYR and OXY, respectively, feeding on RHO. The discrepancies between these specific works and our results will be discussed later.…”

“…The results are averages of 4 replicates; corresponding SE are given in parentheses below the values. AE was ex pressed as (μc + Rc) / Ic × 100; where μc and Ic = carbon-specific growth and ingestion rates, respectively GYR can also take advantage of discrete food supply, as demonstrated by Schmoker et al (2011), and by the evidence found in this study. For instance, it also showed some short-term superfluous feeding when previously starved; although to a lower extent than OXY.…”

Microzooplankton community structure investigated with imaging flow cytometry and automated live-cell staining

“…During the spring and summer, when the gyrodinoid morphotype was predominantly chlorophyll-containing, it may have been feeding on small autotrophs. Certain species of gyrodinoids, such as Gyrodinium dominans, have been found to respond quickly to increases in cryptophytes (Schmoker et al 2011), which can be important at that time of year.…”

Growth, Grazing, and Starvation Survival in Three Heterotrophic Dinoflagellate Species

“…; Schmoker et al. ), there are, to our knowledge, no reports of heterotrophic dinoflagellate growth rates after starvation. The focus of this study was to compare the functional and numerical responses of three cosmopolitan heterotrophic dinoflagellates ( O. marina , Gyrodinium spirale and G. dominans ) in response to different food conditions (continuously‐fed vs. starved) and over different time scales (hours vs. days).…”