Comparison of ciliate communities in the anoxic hypolimnia of three lakes: general features and the influence of lake characteristics

Guhl, Barbara E.; Finlay, Bland J.; Schink, Bernhard

doi:10.1093/plankt/18.3.335

Cited by 35 publications

(43 citation statements)

References 44 publications

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“…This is in contrast to the observations of Brę k-Laitinen et al (2012), who found distinct ciliate communities in the epilimnion and hypolimnion of Lake Vesijärvi, and Guhl et al (1996), who reported less diverse ciliate communities in the oxygendepleted hypolimnion of Priest Pot and Esthwaite Water in the English Lake District and Lake Arcas in Spain. These authors suggested that, in addition to oxygen, the clear diversity patterns stem from monotonous food sources in the anoxic waters.…”

Section: Discussioncontrasting

confidence: 98%

“…In general, the abundance and vertical distribution of the grazers in MFWs is controlled by food and/or oxygen availability (Guhl et al 1996). Many studies have reported NF grazing on bacteria-sized particles (Sherr & Sherr 2002 and references therein), and since bacteria are abundant in humic lakes, NF growth is supposedly not limited by the availability of bacterial food resources.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

“…1995, Tulonen et al 2000. The high amount of OM sustains the high biomass of heterotrophic bacteria, which further support the growth of microzooplankton and macrozooplankton (Jones 1992, Daniel et al 2005.In general, the abundance and vertical distribution of the grazers in MFWs is controlled by food and/or oxygen availability (Guhl et al 1996). Many studies have reported NF grazing on bacteria-sized particles (Sherr & Sherr 2002 and references therein), and since bacteria are abundant in humic lakes, NF growth is supposedly not limited by the availability of bacterial food resources.…”

mentioning

confidence: 99%

“…2012, whereas the abundance and community structure of ciliated protozoa differ considerably in oxic versus anoxic waters (Guhl et al 1996, Gobler et al 2008, Brę k-Laitinen et al 2012. Some ciliates have specialized diets and are thus dependent on the location of their food resources (Amblard et al 1995, Guhl et al 1996, Verni & Gualtieri 1997, Gobler et al 2008, Brę k-Laitinen et al 2012.Since hypolimnetic oxygen depletion divides the water column into 2 separate parts, and since there are few studies of MFWs in humic lakes, we examined the vertical structure of the MFW in a strongly stratified boreal humic lake with an anoxic hypolimnion. In this lake, the anoxia has strengthened as a consequence of climate change (E. Peltomaa et al unpubl.).…”

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confidence: 99%

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Weak response of the microbial food web of a boreal humic lake to hypolimnetic anoxia

Peltomaa

Zingel

Ojala

2013

Aquat. Microb. Ecol.

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As a consequence of climate change, thermal stratification in lakes strengthens and increases the tendency towards hypolimnetic hypoxia or even anoxia. In the boreal zone, numerous lakes already undergo seasonal hypolimnetic anoxia, but its consequences for the microbial food web (MFW) are still largely unknown. However, the abundance as well as vertical distribution of predators, especially ciliates, in the MFW is generally assumed to be controlled by food and oxygen availability. To determine whether oxygen regulates the MFW, we studied the autotrophic picoplankton (APP), larger phytoplankton, bacteria, nanoflagellates (NFs) and ciliates present throughout the growing season in a small, humic and seasonally strongly stratified lake (ValkeaKotinen) with an anoxic hypolimnion. The prey numbers in Lake Valkea-Kotinen were low, whereas the predators were numerous. The abundance of NFs, which was coupled with that of bacteria, was especially high. However, our results indicated no clear response to oxygen conditions, although the abundances of the predators were generally higher in the oxic than in the anoxic water layers. The only ciliate feeding group that showed a clear response was the omnivores, which thrived in the hypoxic hypolimnion in early summer. The APP and bacterial abundances were in general high in the upper hypolimnion near the thermocline, which in Lake Valkea-Kotinen is prone to convective mixing. This diurnal disturbance nurtures the autotrophic and heterotrophic community around the thermocline and may also explain the rather high predator abundance in the MFW of Lake Valkea-Kotinen.KEY WORDS: Autotrophic picoplankton · Bacteria · Heterotrophic nanoflagellates · Ciliates · Thermocline · Convection Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 68: 91-105, 2013 92 place macrozooplankton as the main grazers (Masson & Pinel-Alloul 1998).In the boreal zone, numerous lakes regularly undergo seasonal hypolimnetic hypoxia and finally anoxia. The special characteristic of these usually small lakes is the high concentration of coloured organic matter (OM) deriving from the catchment, and thus MFW studies in these types of lakes typically focus on bacterial utilization of allochthonous carbon and ignore comprehensive description of the trophic structure of MFWs. Usually boreal lakes are dimictic, but as small and sheltered bodies of water they often undergo incomplete spring turnover and thus their hypolimnia remain anoxic after winter (Huotari et al. 2009). Due to rapid light attenuation, phytoplankton production in humic lakes is restricted to the upper few metres (Arvola 1984, Karlsson et al. 2009, Peltomaa & Ojala 2010. This results in depletion of epilimnetic inorganic nutrients -most often phosphorus -during summer. However, the nutrients are often abundant in the hypolimnia (Arvola 1984). Phytoplankton communities in humic lakes are dominated by flagellated species capable of migrating vertically between the epilimnion and the hypolimni...

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Section: Discussioncontrasting

confidence: 98%

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%