WIDESPREAD PHAGOCYTOSIS OF CILIATES AND OTHER PROTISTS BY MARINE MIXOTROPHIC AND HETEROTROPHIC THECATE DINOFLAGELLATES¹

Abstract

An electron microscopic examination of large amorphous inclusions located in a variety of photosynthetic thecate dinoflagellates (Alexandrium ostenfeldii (Paulsen) Balech et Tangen, Gonyaulax diegensis Kofoid, Scrippsiella sp., Ceratium longipes (Bailey) Gran, and Prorocentrum micans Ehrenberg) and a nonphotosynthetic thecate species (Amylax sp.) revealed each inclusion to be a food vacuole, the majority of which were ingested ciliate prey. Recognizable features of these ciliates included linear arrays of basal bodies and cilia consistent with oligotrich polykinetid structure, characteristic macronuclei, chloroplasts (evidently kleptoplastids), cup‐shaped starch plates, and cylindrical extrusomes. Three species contained (apparent) nonciliate prey: Scrippsiella sp., whose food vacuoles consistently contained unusual and complex extrusome‐like cylindrical bodies having a distinctive six‐lobed, multilayered structure; P. micans, which contained an unidentified encysted cell; and a single A. ostenfeldii cell, containing a Dinophysis sp. dinoflagellate cell. Several food vacuoles of ciliate origin had a red hue. This, together with the resemblance of A. ostenfeldii cells to planozygotes, suggests that similar structures previously identified as accumulation bodies may in fact be food vacuoles and that feeding may in some cases be associated with sexual processes.

Phytoplankton and microzooplankton variability between the Subtropical and Polar Fronts south of Australia: Thriving under regenerative and new production in late summer

“…As reported by various authors [e.g., Gaines and Elbrachter, 1987] most of the known dinoflagellate species are heterotrophic or phagotrophic (mixotrophic) in nutrition, and there exist only very few obligatory phototrophic species [Lessard, 1991;Okolodkov, 1999]. For this reason the heterotrophic dinoflagellates chosen by us also include, except for the long known heterotrophs such as Protoperidiniurn, Gyrodiniurn, and Gyrnnodiniurn, such genera as Arnphidiniurn, Gonyaulax, and Ceratiurn, with the latter observed to feed on ciliates [Jacobson and Anderson, 1996].…”

Phagotrophy in phototrophs

“…Life form of organism (sensu Luther 1949): pla-planktophyte (small, in water body); ple-pleustophyte (large, in water body or resting on substrate); ha-haptophyte (attached to substrate particle that is large relative to size of organism); rhi-rhizophyte (with attachment organs in substratum of small particle size relative to the organism). Information presented in this table is from Albert et al 1992;Bennett et al 1990;Car-on et al 1990Car-on et al , 1993Clark 1992;Jacobsen and Anderson 1996;Jones et al 1994;Juniper et al 1989;Law and Lewis 1983;Marin and Ros 1992;Nygaard and Tobieson 1993;Raven 1981Raven , 1993aSmith and Douglas 1987;Tranvik et al 1989;andWilcox andWedemayer 1985, 1991 ic capacity and a low specific growth rate when relying on light and inorganic elemental supplies (C, N, P) (Myers and Graham 1956;Lewitus and Caron 1991). Chemoorganotrophic nutrition by saprotrophic use of glucose or by bacterivory gives much higher growth rates that are independent of light, NH4+, and H,PO,-.…”

Uptake of high molecular weight dextran by the dinoflagellate Alexandrium catenella

“…Whether or not PAS bodies have a similar function to food vacuoles is still an open question. Jacobson & Anderson (1996) hypothesized that inclusions with yellow autofluorescence in A. ostenfeldii may be digested remains of prey which would supply nutrient storage prior encystment.…”