Differentiation betweenPhaeocystis pouchetii (Har.) Lagerheim andPhaeocystis globosa Scherffel

Abstract

An Arctic clone of Phaeocystispouchetii LAGERHEIM was compared to Phaeocystis globosa SCHERFFEL isolated from the southern North Sea with regard to temperature tolerance and colony shapes. Already young P.pouchetii colonies (< 100/~m) show the typical distribution of the cells in groups, separated from each other by wide zones of cell-free mucilage; the maximum colony size is ca 2 mm in diameter. P.pouchetii colonies form clouds with bubble-like vesicles, spherical colony-shapes are seldom found. P.g/obosa colonies are spherical up to a size of 2 mm; the cells are distributed homogeneously over the periphery of the colonies. A 'pouchetii'-Iike distribution of cells never occurs either in the spherical young colonies or in the pear-shaped old colonies (size up to 8 mm). A development from the colony shape of the 'globosa'-type to the 'pouchetii'-type or vice versa was never found. Therefore the colony shape has to be considered a constant distinctive character. Single cells of P, pouchetii and P.globosa cannot be separated from each other by using the light microscope; this also holds for the flagellates and the non-motile cells. P.pouchetii grows well between 0 ~ and 14 ~ P.g/obosa between 4 ~ and 22 ~ respectively. Because of the distinctive differences in the morphology of the colonies and the differences in temperature tolerances we propose that Phaeocystis globosa should no longer be considered conspecific with Phaeocystis pouchetii.

Effect of increases in temperature and nutrients on phytoplankton community structure and photosynthesis in the western English Channel

“…), which usually occurred at temperatures <14°C. This has also been observed in other studies (Jahnke & Baumann 1987). According to the 'Margalef mandala', the stability of the water column is an important factor in controlling phytoplankton succession (Margalef 1978).…”

Grazing pressure of the calanoid copepod Temora longicornis on a Phaeocystis dominated spring bloom in a Dutch tidal inlet

“…Phytopiankton carbon was calculated by assuming that the chl a ratio Phaeocystisldiatoms equals the biovolume ratio Phaeocystisldiatoms in the samples and by applying a carbon/chl a ratio of 25 in diatoms (Riemann et al 1982) and 29 in Phaeocystis (Lancelot-van Beveren 1980). The Phaeocystis colonies in the samples were all of the globosa-type (Jahnke & Baumann 1987).…”

A taxonomic review of the genus Phaeocystis

“…The colonial stage, with cells very loosely interconnected and enclosed in a thin skin (Hamm et al 1999), is most easily recognized, although some species may form mucilaginous colonies or do not seem to have a colonial stage. Thousands of cells can occur in a colony that may reach 2 cm in diameter (Jahnke and Baumann 1987;Verity et al 1988;Rousseau et al 1994;Davidson and Marchant 1992). Colony sizes of 3 cm or more have been reported in blooms from China (Shen et al 2004).…”

“…Phaeocystis pouchetii (its correct orthography) occurs in cold waters and in its globular, lobed colonies, cells are arranged in packets of four (see Jahnke and Baumann 1987 for illustrations). Phaeocystis globosa was described by ScherVel (1900) from temperate waters and forms spherical colonies with cells arranged homogeneously within the colony (Jahnke and Baumann 1987), whereas older stages can assume distorted pear shapes (Bätje and Michaelis 1986). Early workers separated P. pouchetii and P. globosa based on diVerent distributions and colonial morphologies until Kornmann (1955) doubted the diVerentiation between the two species.…”