Grazing by the heterotrophic dinoflagellate Protoperidinium steinii on a Ceratium bloom

Abstract

Variations in heterotrophic dinoflagellate populations at a station in the inner Oslofjord, Norway, were studied by sampling at ca 4 d intervals. Cells were concentrated from 1 l samples by filtration before being counted in an inverted microscope. Additional data include autotrophic carbon biomass estimates based on microscopy of the phytoplankton, chlorophyll a (chl a) concentrations, and hydrography. A modest (2 to 4 µg chl a l -1 ) diatom bloom in September was followed by a large (up to 128 µg chl a l -1 ) dinoflagellate bloom in October, dominated by Ceratium furca. Altogether 25 thecate heterotrophic dinoflagellate species were recorded in this study. Their total biomass at all times was <1% of that of the autotrophic phytoplankton. Coinciding with the Ceratium bloom, there was a marked growth in Protoperidinium steinii, with cell numbers reaching > 2000 cells l -1. P. pyriforme, P. brevipes, P. curtipes, and Oblea rotunda showed more modest increases, while no significant response was seen in any of the other 20 heterotrophic dinoflagellates. In incubated plankton samples, we recorded 81 instances of P. steinii feeding on C. furca or on other dinoflagellates. Our study confirms previous laboratory findings suggesting that P. steinii belongs to the limited selection of Protoperidinium species capable of exploiting dinoflagellate prey in the natural environment. KEY WORDS: Oslofjord · Heterotrophic dinoflagellates · Protoperidinium steinii · Grazing · Ceratium furca Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 225: [161][162][163][164][165][166][167] 2002 lius & Kuylenstierna 1996, Matsuyama et al. 1999). This approach was used in a recent investigation of Protoperidinium species in the inner Oslofjord, based on approximate monthly sampling through 1 yr (Kjaeret et al. 2000). The present study from the same area made use of much more closely repeated sampling, carried out over 2 mo in the autumn during which a modest bloom consisting mainly of the diatom Pseudo-nitzschia pseudodelicatissima was succeeded by a large bloom dominated by the dinoflagellate Ceratium furca. Our goal was to see if close sampling combined with observations of live samples could provide more conclusive evidence of predator-prey relationships involving Protoperidinium spp. MATERIALS AND METHODSThe material was collected in the inner Oslofjord at or near the station Nakkholmen (59°53' N, 10°41' E) at time intervals of 2 to 7 d, from September 7 to November 1, 2000. Data on water temperature and salinity were obtained by means of a mini-STD probe. Sampling for chlorophyll a (chl a) was carried out by Niskin bottle casts from the surface to 20 m depth. The samples were filtered onto Whatman GF/C glass fiber filters (pore size ca 1 µm) and extracted with 90% acetone according to Strickland & Parsons (1972) for subsequent analysis in a Turner Designs TD-700 fluorometer. Samples for quantitative microscopy and for observations on live plankton were taken from 2 m depth, suppl...

Influence of benthic and pelagic environmental factors on the distribution of dinoflagellate cysts in surface sediments along the Swedish west coast

“…This suggests that water column mixing results in relatively more cysts being produced from heterotrophic species, probably via an increased diatom-rich food supply. The majority of Protoperidinium species appear to be diatom grazers, but some species can also utilize dinoflagellate prey (Jeong 1999, Olseng et al 2002. Field observations of planktonic Protoperidinium spp.…”

Taxonomy of dinoflagellates, the genus Protoperidium (Archaeperidinium), in coastal waters of Vietnam

“…Protoperidinium Bergh (1881) là một chi lớn của tảo hai roi (dinoflagellates), thường không có lục lạp và xem như là dị dưỡng [38]. Các tấm vỏ của chi tảo này được đặc trưng bởi ba tấm đai kết hợp với một tấm chuyển tiếp [5], và hiện nay có khoảng 280 loài [18].…”

Growth rates and starvation survival of three species of the pallium-feeding, thecate dinoflagellate genus Protoperidinium

“…Published coastal abundances of Protoperidinium spp. are usually < 5 cells ml -1 (Lessard 1991, Kjaeret et al 2000, Olseng et al 2002. Our own laboratory cultures have infrequently reached maximum concentrations of about 140 cells ml -1 for P. conicum and P. excentricum.…”

“…Populations of these 2 species would take more than 2 d to double in biomass. Olseng et al (2002) attributed rapid increases in Protoperidinium abundance to advection because growth rates of >1 division d -1 were considered highly unlikely. However, the measured maximum growth rate for P. conicum was more than twice the rate predicted from Hansen et al's (1997) regression, and was greater than most reported growth rates for the genus Protoperidinium ( Table 2).…”