Growth, feeding and ecological roles of the mixotrophic and heterotrophic dinoflagellates in marine planktonic food webs

Abstract

Planktonic mixotrophic and heterotrophic dinoflagellates are ubiquitous protists and often abundant in marine environments. Recently many phototrophic dinoflagellate species have been revealed to be mixotrophic organisms and also it is suggested that most dinoflagellates may be mixotrophic or heterotrophic protists. The mixotrophic and heterotrophic dinoflagellates are able to feed on diverse prey items including bacteria, picoeukaryotes, nanoflagellates, diatoms, other dinoflagellates, heterotrophic protists, and metazoans due to their diverse feeding mechanisms. In turn they are ingested by many kinds of predators. Thus, the roles of the dinoflagellates in marine planktonic food webs are very diverse. The present paper reviewed the kind of prey which mixotrophic and heterotrophic dinoflagellates are able to feed on, feeding mechanisms, growth and ingestion rates of dinoflagellates, grazing impact by dinoflagellate predators on natural prey populations, predators on dinoflagellates, and red tides dominated by dinoflagellates. Based on this information, we suggested a new marine planktonic food web focusing on mixotrophic and heterotrophic dinoflagellates and provided an insight on the roles of dinoflagellates in the food web.

The role of mixotrophic protists in the biological carbon pump

“…They photosynthesize using their intrinsic chloroplasts (for which they contain full genetic control; see , while obtaining nutrition through the ingestion of bacteria, hence competing with the HNFs for bacterial prey. While mixotrophic algal protists have been shown to feed on a wide array of types and sizes of prey (Jeong et al, 2010), in the system that we consider, bacteria are the primary prey item (Hartmann et al, 2012).…”

“…eutrophic, mesotrophic and oligotrophic, coastal to open-ocean systems; Pitta and Giannakourou, 2000;Burkholder et al, 2008;Hartmann et al, 2012;Sanders and Gast, 2012) as well as freshwater systems (Sanders, 1991a). Indeed, there is increasing evidence that in most aquatic systems the majority of protists are mixotrophs engaging in varying proportions of phototrophy and phagotrophy (Sanders, 1991b;Burkholder et al, 2008;Raven et al, 2009;Stoecker et al, 2009;Jeong et al, 2010;Lindehoff et al, 2010;Hansen, 2011;Johnson, 2011). Often the marine ecosystems are heavily dependent upon the activity of these mixotrophic protists (Pitta and Giannakourou, 2000;Unrein et al, 2007;Zubkov and Tarran, 2008;Hartmann et al, 2012;Sanders and Gast, 2012).…”

Molecular insights into a dinoflagellate bloom

“…produced by bacteria to prolong the bloom. Alternatively, if the blooming dinoflagellates are mixotrophic, which many of them are (Jeong et al, 2010), bacterial cultivation may provide a source of organic matter when inorganic nutrients are depleted to levels where autotrophy is no longer favored.…”

Analysis of the hydrographic conditions and cyst beds in the San Jorge Gulf, Argentina, that favor dinoflagellate population development including toxigenic species and their toxins

“…However, there were less toxins detected in the larger 50-200 μm and N200 μm size fractions (Table 8), which indicates that toxin transfer to higher trophic levels did not play an important role. However, heterotrophic and mixotrophic dinoflagellates are known for a low predator:prey size ratio (Hansen et al, 1994;Jeong et al, 2010) and thus may transfer toxins among species of the same size.…”