Morphology and in situ sedimentation of the cysts of a planktonic oligotrich ciliate, Strombidium capitatum

Abstract

The cysts of the oligotrich ciliate Strombidium capitatum isolated from the natural sediments in Onagawa Bay, Japan, and Masan Bay, Korea, were described and incubated to produce vegetative cells. The vegetative cells that were obtained were observed after protargol staining and with a scanning microscope and then described. The cysts of S. capitatum were spherical with a papula and spiny surface. Their size varied from 55 to 62 µm in total length and from 45 to 55 µm in width. Seasonal changes in the vegetative population and in sedimentation of the newly formed cysts were investigated in situ in both bays. Planktonic vegetative cells peaked in autumn (December) in Onagawa Bay and in spring (April) in Masan Bay, when water temperature was ca. 15°C. In contrast, the cells were not detected in either bay in summer. Mass encystment occurred in March in Onagawa Bay and in November in Masan Bay without coincidence with the peaks in vegetative populations at either locality. These results indicate that S. capitatum is adapted to low and moderate temperatures and aestivates during warm summer.KEY WORDS: Strombidium capitatum · Cyst morphology · Cyst sedimentation · Oligotrich ciliate · Excystment · Onagawa Bay · Masan Bay Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 53: [173][174][175][176][177][178][179] 2008 We isolated a type of oligotrich cyst possessing a papula from marine sediments in Korean and Japanese embayments facing respectively to the East/Japan Sea and the northwest Pacific, which was identified to be Strombidium capitatum on the basis of the excysted vegetative cells. To illustrate and compare population dynamics in 2 localities, we observed the seasonality of vegetative and cyst populations in the 2 embayments. MATERIALS AND METHODSPlanktonic population and sinking cysts in the water column. Abundance of Strombidium capitatum in the water column was investigated monthly from July 1993 to July 1994 at a station in Onagawa Bay, Japan, and from October 2005 to November 2006 at a station in Masan Bay, Korea (Fig. 1). Average water depths at the stations were 17 and 10 m, respectively. Water samples were collected using a Van Dorn bottle at 0.5, 10, and 15 m (adding 15 m in 1994) in Onagawa Bay and at 0.5 m in Masan Bay. The samples were fixed immediately in Bouin's solution at a final concentration of 5% and then treated with the quantitative protargol staining (QPS) method (Montagnes & Lynn 1987). Water temperature and salinity were recorded using a digital bathythermograph. Chlorophyll a (chl a) concentration in Onagawa Bay was measured for 2 size fractions using in vivo fluorometry.In Onagawa Bay, sinking cysts were collected with a cylindrical sediment trap of 58 cm in height and 14 cm in inner diameter. The basic configuration of the trap is given by Sasaki & Nishizawa (1981). The trap was deployed at 12 m depth intermittently, typically for 3 to 7 d mo -1 from July 1993 to July 1994. Although a similar cylindrical trap of 45 cm in heigh...

Reconciling Cladistic and Genetic Analyses in Choreotrichid Ciliates (Ciliophora, Spirotricha, Oligotrichea)

“…Besides the data already analysed by Agatha and Strüder‐Kypke (), recent findings from live and silver‐impregnated specimens and electron microscopic studies are included (Agatha , , b, ; Agatha and Foissner ; Agatha and Tsai ; Foissner et al. ; Kim and Taniguchi ; Kim Y.‐O. et al.…”

“…The consideration of the halteriids and oligotrichids in the present cladistic analysis of the choreotrichids allows not only the reconstruction of the last common ancestor, which entered the pelagial, but also the detection of convergences and adaptations to the planktonic life style. Besides the data already analysed by Agatha and Stru¨der-Kypke (2007), recent findings from live and silver-impregnated specimens and electron microscopic studies are included (Agatha 2008(Agatha , 2010a(Agatha , b, 2011Agatha and Foissner 2009;Agatha and Tsai 2008;Foissner et al 2007;Kim and Taniguchi 2007;Kim Y.-O. et al 2008Kim Y.-O.…”

Global Diversity of Aloricate Oligotrichea (Protista, Ciliophora, Spirotricha) in Marine and Brackish Sea Water

“…Apparently, open water species follow a seasonal encystment-excystment cycle [39], [41], [48], whereas the oligotrichid tide-pool ciliate Strombidium oculatum demonstrates a circatidal behaviour, encysting before high tide and excysting during low tide [42]–[44], [46], [49]–[51]. The resting cysts are flask-shaped or spindle-shaped with a solid, hollow, or frothy plug closing the emergence pore.…”

Seasonal Dynamics of Ciliate Cysts and the Impact of Short-Term Change of Salinity in a Eutrophic Coastal Marine Ecosystem

“…The most frequently used cyst collection methods are long term using sediment traps to obtain flux from surface over several weeks or months (Müller 1996;Müller and Wünsch 1999;Kim et al 2008). However, this method is difficult to compare with environment factors directly.…”