Mixotrophy in the Phototrophic Harmful Alga Cochlodinium polykrikoides (Dinophycean): Prey Species, the Effects of Prey Concentration, and Grazing Impact

Abstract

We first reported here that the harmful alga Cochlodinium polykrikoides, which had been previously known as an autotrophic dinoflagellate, was a mixotrophic species. We investigated the kinds of prey species and the effects of the prey concentration on the growth and ingestion rates of C. polykrikoides when feeding on an unidentified cryptophyte species (Equivalent Spherical Diameter, ESD = 5.6 microm). We also calculated grazing coefficients by combining field data on abundances of C. polykrikoides and co-occurring cryptophytes with laboratory data on ingestion rates obtained in the present study. Cocholdinium polykrikoides fed on prey cells by engulfing the prey through the sulcus. Among the phytoplankton prey offered, C. polykrikoides ingested small phytoplankton species that had ESD's< or = 11 microm (e.g. the prymnesiophyte Isochrysis galbana, an unidentified cryptophyte, the cryptophyte Rhodomonas salina, the raphidophyte Heterosigma akashiwo, and the dinoflagellate Amphidinium carterae). It did not feed on larger phytoplankton species that had ESD's > or = 12 microm (e.g. the dinoflagellates Heterocapsa triquetra, Prorocentrum minimum, Scrippsiella sp., Alexandrium tamarense, Prorocentrum micans, Gymnodinium catenatum, Akashiwo sanguinea, and Lingulodinium polyedrum). Specific growth rates of C. polykrikoides on a cryptophyte increased with increasing mean prey concentration, with saturation at a mean prey concentration of approximately 270 ng C ml(-1) (i.e. 15,900 cells ml(-1)). The maximum specific growth rate (mixotrophic growth) of C. polykrikoides on a cryptophyte was 0.324 d(-1), under a 14:10 h light-dark cycle of 50 microE m(-2) s(-1), while its growth rate (phototrophic growth) under the same light conditions without added prey was 0.166 d(-1). Maximum ingestion and clearance rates of C. polykrikoides on a cryptophyte were 0.16 ng C grazer(-1)d(-1) (9.4 cells grazer(-1)d(-1)) and 0.33 microl grazer(-1)h(-1), respectively. Calculated grazing coefficients by C. polykrikoides on cryptophytes were 0.001-0.745 h(-1) (i.e. 0.1-53% of cryptophyte populations were removed by a C. polykrikoides population in 1 h). The results of the present study suggest that C. polykrikoides sometimes has a considerable grazing impact on populations of cryptophytes.

Feeding by the mixotrophic red-tide dinoflagellate Gonyaulax polygramma: mechanisms, prey species, effects of prey concentration, and grazing impact

“…The maximum ingestion and clearance rates of Gonyaulax polygramma feeding on a unialgal diet of a cryptophyte under the conditions provided in the present study (10.6 cells grazer (Jeong et al 2004). Therefore, G. polygramma may compete with C. polykrikoides for a cryptophyte prey if they co-occur.…”

“…Recently, red-tide dinoflagellates, previously known as phototrophic dinoflagellates, have been revealed to be mixotrophic (Bockstahler & Coats 1993, Jacobson & Anderson 1996, Granéli et al 1997, Stoecker et al 1997, Smalley et al 1999, Stoecker 1999, Skovgaard 2000, Jeong et al 2004). The thecate dinoflagellate Gonyaulax polygramma has caused red tides in the ABSTRACT: The red-tide dinoflagellate Gonyaulax polygramma (GenBank accession number = AJ833631), previously known as an exclusively autotrophic dinoflagellate, has been found to be a mixotrophic species.…”

Distribution of the heterotrophic dinoflagellate Pfiesteria piscicida in Korean waters and its consumption of mixotrophic dinoflagellates, raphidophytes and fish blood cells

“…; Jeong et al 2004aJeong et al , 2005c. According to our field data, the maximum abundances of P. piscicida (combined with PLDs) in Korean waters were ca.…”

Deleterious consequences of a red tide dinoflagellate Cochlodinium polykrikoides for the calanoid copepod Acartia tonsa

“…Bloom patches can achieve cell densities exceeding 10 5 cells ml -1 (Gobler et al 2008). C. polykrikoides isolated in East Asia can be mixotrophic, feeding on small phytoplankton species (<11 μm) by engulfing the prey through the sulcus (Jeong et al 2004). Strong diel vertical migration has been observed in field populations of C. polykrikoides (Park et al 2001).…”