Limits...
Portrait of a Geothermal Spring, Hunter's Hot Springs, Oregon.

Castenholz RW - Life (Basel) (2015)

Bottom Line: All of these demarcations are easily visible in the field.In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology.Most of the temperature and chemical limits have been explained by field and laboratory experiments.

View Article: PubMed Central - PubMed

Affiliation: Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA. rcasten@uoregon.edu.

ABSTRACT
Although alkaline Hunter's Hot Springs in southeastern Oregon has been studied extensively for over 40 years, most of these studies and the subsequent publications were before the advent of molecular methods. However, there are many field observations and laboratory experiments that reveal the major aspects of the phototrophic species composition within various physical and chemical gradients of these springs. Relatively constant temperature boundaries demark the upper boundary of the unicellular cyanobacterium, Synechococcus at 73-74 °C (the world-wide upper limit for photosynthesis), and 68-70 °C the upper limit for Chloroflexus. The upper limit for the cover of the filamentous cyanobacterium, Geitlerinema (Oscillatoria) is at 54-55 °C, and the in situ lower limit at 47-48 °C for all three of these phototrophs due to the upper temperature limit for the grazing ostracod, Thermopsis. The in situ upper limit for the cyanobacteria Pleurocapsa and Calothrix is at ~47-48 °C, which are more grazer-resistant and grazer dependent. All of these demarcations are easily visible in the field. In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology. Most of the temperature and chemical limits have been explained by field and laboratory experiments.

No MeSH data available.


Related in: MedlinePlus

Geitlerinema terebriformis mat contracted and retreating under high midday light intensity at 49–53 °C, revealing Chloroflexus undermat, originally covered by the motile G. terebriformis mat during period of low light (Figure 7 in [15]).
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life-05-00332-f008: Geitlerinema terebriformis mat contracted and retreating under high midday light intensity at 49–53 °C, revealing Chloroflexus undermat, originally covered by the motile G. terebriformis mat during period of low light (Figure 7 in [15]).

Mentions: Castenholz [15] showed that at <55 °C in this and similar hot springs (e.g., Kah-nee-ta Hot Springs, Oregon), when the substrate was soft, G. terebriformis trichomes had a vertical downward “escape” movement to 1–2 mm below the substrate under high light intensity in addition to the clumping response [15,16,18] (Figure 6 and Figure 7). In addition to the consolidation of the G. terebriformis mat in response to increasing light intensity, the mat edge showed a phobic response to a temperature above 54–55 °C, i.e., upper temperature limit for growth when the stream flow changed [15]. The convergence and retreat of the mat with increasing light intensity or the advance of higher temperature also exposed, in many cases, an under-mat of orange or pink-colored Chloroflexus (Figure 8). This under-mat of Chloroflexus was visible as well at higher temperatures, below the Synechococcus top cover below about 68 °C (Figure 1 and Figure 2). G. terebriformis did not occur in at least one of the springs at Hunter’s (i.e., “Fenceline” an unofficial name) [20]. No macro-chemical differences were shown for this spring, and the basis of this difference was never established.


Portrait of a Geothermal Spring, Hunter's Hot Springs, Oregon.

Castenholz RW - Life (Basel) (2015)

Geitlerinema terebriformis mat contracted and retreating under high midday light intensity at 49–53 °C, revealing Chloroflexus undermat, originally covered by the motile G. terebriformis mat during period of low light (Figure 7 in [15]).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390855&req=5

life-05-00332-f008: Geitlerinema terebriformis mat contracted and retreating under high midday light intensity at 49–53 °C, revealing Chloroflexus undermat, originally covered by the motile G. terebriformis mat during period of low light (Figure 7 in [15]).
Mentions: Castenholz [15] showed that at <55 °C in this and similar hot springs (e.g., Kah-nee-ta Hot Springs, Oregon), when the substrate was soft, G. terebriformis trichomes had a vertical downward “escape” movement to 1–2 mm below the substrate under high light intensity in addition to the clumping response [15,16,18] (Figure 6 and Figure 7). In addition to the consolidation of the G. terebriformis mat in response to increasing light intensity, the mat edge showed a phobic response to a temperature above 54–55 °C, i.e., upper temperature limit for growth when the stream flow changed [15]. The convergence and retreat of the mat with increasing light intensity or the advance of higher temperature also exposed, in many cases, an under-mat of orange or pink-colored Chloroflexus (Figure 8). This under-mat of Chloroflexus was visible as well at higher temperatures, below the Synechococcus top cover below about 68 °C (Figure 1 and Figure 2). G. terebriformis did not occur in at least one of the springs at Hunter’s (i.e., “Fenceline” an unofficial name) [20]. No macro-chemical differences were shown for this spring, and the basis of this difference was never established.

Bottom Line: All of these demarcations are easily visible in the field.In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology.Most of the temperature and chemical limits have been explained by field and laboratory experiments.

View Article: PubMed Central - PubMed

Affiliation: Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA. rcasten@uoregon.edu.

ABSTRACT
Although alkaline Hunter's Hot Springs in southeastern Oregon has been studied extensively for over 40 years, most of these studies and the subsequent publications were before the advent of molecular methods. However, there are many field observations and laboratory experiments that reveal the major aspects of the phototrophic species composition within various physical and chemical gradients of these springs. Relatively constant temperature boundaries demark the upper boundary of the unicellular cyanobacterium, Synechococcus at 73-74 °C (the world-wide upper limit for photosynthesis), and 68-70 °C the upper limit for Chloroflexus. The upper limit for the cover of the filamentous cyanobacterium, Geitlerinema (Oscillatoria) is at 54-55 °C, and the in situ lower limit at 47-48 °C for all three of these phototrophs due to the upper temperature limit for the grazing ostracod, Thermopsis. The in situ upper limit for the cyanobacteria Pleurocapsa and Calothrix is at ~47-48 °C, which are more grazer-resistant and grazer dependent. All of these demarcations are easily visible in the field. In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology. Most of the temperature and chemical limits have been explained by field and laboratory experiments.

No MeSH data available.


Related in: MedlinePlus