Growth and Grazing Rates of the Heterotrophic Dinoflagellate Polykrikos kofoidii on Red‐Tide and Toxic Dinoflagellates

Abstract

We investigated growth rates, grazing rates, and prey selection of Polykrikos kofoidii when feeding on several species of red-tide and/or toxic dinoflagellates. Polykrikos kofoidii ingested all prey species used in this study, exhibiting positive growth on Lingulodinium polyedrum, Scrippsiella trochoidea, Ceratium furca, Gymnodinium catenatum, Gyrodinium impudicum, Prorocentrum micans, and the toxic dinoflagellate Amphidinium carterae, but not on P. minimum. Specific growth rates of P. kofoidii increased rapidly with increasing density of L. polyedrum, S. trochoidea, C. furca, and G. catenatum before saturating between 500-2,000 ng C ml(-1). Specific growth rates increased continuously when P. kofoidii was fed the other prey species. Maximum specific growth rates of P. kofoidii on G. catenatum (1.12 d(-1)), S. trochoidea (0.97 d(-1)), and L. polyedrum (0.83 d(-1)) were higher than those on C. furca (0.35 d(-1)), A. carterae (0.10 d(-1)), P. micans (0.06 d(-1)), G. impudicum (0.06 d(-1)), and P. minimum (-0.03 d(-1)). Threshold prey concentrations (where net growth = 0) were 54-288 ng C ml(-1). Maximum ingestion and clearance rates of P. kofoidii on these dinoflagellates were 5-24 ng C pseudocolony(-1) d(-1) and 1.0-5.9 microl pseudocolony(-1) h(-1), respectively. Polykrikos kofoidii strongly selected L. polyedrum over S. trochoidea in prey mixtures. Polykrikos kofoidii exhibited higher maximum growth, ingestion, and clearance rates than previously reported for the mixotrophic dinoflagellate Fragilidium cf. mexicanum or the heterotrophic dinoflagellates Protoperidinium cf. divergens and P. crassipes, when grown on the same prey species. Grazing coefficients calculated by combining field data on abundances of Polykrikos spp. and co-occurring red-tide dinoflagellate prey with laboratory data on ingestion rates obtained in the present study suggest that Polykrikos spp. sometimes have a considerable grazing impact on prey populations.

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

“…The μ max of Pfiesteria piscicida on Amphidinium carterae (1.21 d ; Jeong et al 1999Jeong et al , 2001bJeong et al , 2002 ) may not be able to compete and thus will be less abundant (Nakamura et al 1995, Jeong et al 2002.…”

“…Gyrodinium spp., and Protoperidinium spp. are 100 to 2000 cells ml -1 (Lessard 1984, Jacobson 1987, Jeong 1995, 1999, Jeong et al 2001b, Sherr & Sherr 2002, Jeong et al 2004b). The effects of P. piscicida and PLD grazing on blooms of the small naked algae tested in the present study may be greater than those of other heterotrophic dinoflagellates, because rates of ingestion by P. piscicida on some of these algae were comparable to those by other heterotrophic dinoflagellates on the same prey.…”

Growth and ingestion rates of heterotrophic dinoflagellates and a ciliate on the mixotrophic dinoflagellate Biecheleria cincta

“…Thus, low ingestion rates for G. moestrupii, G. spirale, and P. kofoidii on B. cincta are likely responsible for their negative growth rates. However, growth rates for G. moestrupii, G. spirale, and P. kofoidii are high when feeding on algal prey (Jeong et al 2001b, Kim and Jeong 2004. The maximum growth rates for G. moestrupii, G. spirale, and P. kofoidii when feeding on optimal prey (e.g., Alexandrium minutum, Prorocentrum minimum, and Gymnodinium catenatum) are as high as 1.60, 1.13, and 1.12 d , respectively (Jeong et al 2001b, Kim and Jeong 2004.…”

“…However, growth rates for G. moestrupii, G. spirale, and P. kofoidii are high when feeding on algal prey (Jeong et al 2001b, Kim and Jeong 2004. The maximum growth rates for G. moestrupii, G. spirale, and P. kofoidii when feeding on optimal prey (e.g., Alexandrium minutum, Prorocentrum minimum, and Gymnodinium catenatum) are as high as 1.60, 1.13, and 1.12 d , respectively (Jeong et al 2001b, Kim and Jeong 2004. We assume that the ecological niches of G. moestrupii, G. spirale, and P. kofoidii may be different from those of O. marina or Strobilidium sp., and competition among these protistan grazers might reduce when feeding on certain prey.…”

“…were relatively high (Table 3) , respectively) were much lower than their carbon contents (0.4, 1.3, and 4.2 ng C cell -1 , respectively) (Jeong et al 2001b, Kim and Jeong 2004). Thus, low ingestion rates for G. moestrupii, G. spirale, and P. kofoidii on B. cincta are likely responsible for their negative growth rates.…”