Effect of hydrostatic pressure on the growth rates and encystment of flagellated protozoa isolated from a deep-sea hydrothermal vent and a deep shelf region

Abstract

Six isolates of deep-sea flagellated protozoa \yere grown in culture at 1 to 300 atm to measure their growth response to increasing hydrostatic pressure. Three kinetoplastid flagellates and 1 choanoflagellate were isolated from deep-sea hydrothermal vent samples and 2 chrysomonads were isolated from deep continental shelf sediments. The growth rates of 2 species isolated from the vent, CaeciteUus parvulus and Rhynchomonas nasuta, were compared to the growth rates of shallow-water strains of the same species. Deep-sea isolates of C. parvulus and R. nasuta had a higher rate of growth at higher pressures than did their shallow-water counterparts. Thls feature could result from adaptation to higher pressure upon sinking to depth or with time on the ocean bottom. Four of the 6 deep-sea isolates-C. parvulus, R. nasuta and the 2 chrysomonads-were capable of growth at pressures corresponding to their respective depths of collect~on, indicating that these species could be metabolically active at these depths. C. parvulus and R. nasuta encysted at pressures greater than their depth of collection. The choanoflagellate isolate was observed to encyst at pressures greater than 50 atm. These findings suggest a potential ecological role for encystment In deep-sea/water-column coupling. Cosmopolitan or epipelag~c species, such as C. parvulus and R nasuta, may be transported on sedimenting particles into the deep sea, where encystment at high pressure could serve as a mechanism for pelagic renewal by advection via hydrothermal plume entrainment and thermohaline circulation.

Tolerance of flagellated protists to high sulfide and metal concentrations potentially encountered at deep-sea hydrothermal vent

“…Hydrothermal vent and shallow-water flagellates were collected and isolated as described by Atkins et al (1998Atkins et al ( , 2000 ( Table 2). Note that both 64 Table 1.…”

“…The question remains as to how some organisms, particularly cosmopolitan species, are able to tolerate and survive under vent conditions. This is especially true for microorganisms like the flagellated protists that arrive in the deep sea on sinking particulate matter (Silver & Alldredge 1981, Patterson & Fenchel 1990) and have been shown to be members of deep-sea benthos (Burnett 1977, Turley et al 1988) and deep-sea vent microenvironments (Atkins et al 1998(Atkins et al , 2000.…”

Molecular identity of strains of heterotrophic flagellates isolated from surface waters and deep-sea sediments of the South Atlantic based on SSU rDNA

“…Among these aggregate-associated flagellates, suspensionand raptorial-feeding species (such as the genera Amastigomonas and Cafeteria) are attached to or move about the surface of aggregates . Since a significant proportion of detritus (and its associated microbial community) may leave the upper layers of the ocean and reach the deep-sea floor (Thiel et al 1990, Gooday & Rathburn 1999 these aggregates are presumed to contribute mainly to the existence of active microbial communities in the deep-sea , Atkins et al 1998, Arndt et al 2003. This could contribute to the wide geographical distribution of some species of flagellates (Caron 1991), as gene flow between the upper layers of the ocean and the deep sea is possible via sedimentation or water currents, as indicated by morphological (Arndt et al 2003) and molecular (Atkins et al 2000) studies.…”

“…This might be an indicator for endemism, although studies on the community structure have not revealed a specific geographic distribution (Lee & Patterson 1998, Al-Qassab et al 2002. The composition of flagellate communities in deep-sea environments and whether it is unique or not, is still unclear (Turley et al 1988, Turley & Carstens 1991, Atkins et al 1998, Hausmann et al 2002, Arndt et al 2003. Nearly all flagellates found in the deep sea have also been reported to occur in other locations , Atkins et al 2000, Arndt et al 2003.…”

Culturing and environmental DNA sequencing uncover hidden kinetoplastid biodiversity and a major marine clade within ancestrally freshwater Neobodo designis

“…Bodonids are common, heterotrophic protozoa that occur in a wide variety of environments, including marine, freshwater and soil, from the tropics to the Arctic (Al-Qassab et al, 2002;Larsen & Patterson, 1990;Patterson & Simpson, 1996;Vørs, 1992Vørs, , 1993. The bodonids Bodo saltans, Neobodo designis and Rhynchomonas nasuta are among the 20 most commonly seen zooflagellates (Patterson & Lee, 2000); it is often suggested that such protists are cosmopolitan and may have wide ecological tolerances (Atkins et al, 1998(Atkins et al, , 2000Finlay, 2002;Patterson & Lee, 2000;Patterson & Simpson, 1996). This frequent assumption of broad physiological tolerance and easy interchange between marine and freshwater environments was recently clearly contradicted for members of the genus Goniomonas, heterotrophic cryptomonads with deeply divergent marine and freshwater clades (von der Heyden et al, 2004a).…”