Aquatic Microbes &
Terrestrial Organic Matter
Spatial
Correlations
&
Temporal
Correlations
Investigating microbes in Rocky Mountain National Park lakes. Building evidence that the terrestrial environment plays a role in shaping microbial communities in lakes.
Searching for microbial community shifts associated with
1) terrestrial influx of organic matter at ice-off (temporal) and
2) higher concentrations of organic matter near lake bottoms (spatial).
Black Lake
Rocky Mountain National Park
photo: Jim Westfall
Temporal
Correlations
Black Lake Intensive
A large influx of organic matter from the surrounding environment is flushed into the lake during spring snowmelt. Peak snowmelt occurs weeks before the lake is free of ice; but given there is likely a lag time for microbes to respond to the incoming organic matter, we waited until the lake was approximately 80% free of ice to begin sampling.
Photo: Jackson Ingram. Pine needles and other plant materials make their way into the lake during snowmelt.
Black Lake ice crystals
Video: Jackson Ingram. Vertical crystals formed overnight on the surface of Black Lake before our first visit. Check out the amazing sound it made as they broke apart under the paddle.
(Also note the large amount of plant debris that had washed into the lake!)
Methods Overview
We timed our visits to capture changes to the microbial community during spring melt. Our first visit was just before the lake melted, but the inlet and outlet streams were flowing. Our next visit we were able to get out on the lake as it was 80% ice-free. The lake was finally ice-free on our third visit and were able to collect samples twice per week for the following two weeks to capture and lag in changes to the microbial community.
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We collected water samples in sterile bottles at four depths within the lake as well as from the inlet and outlet at each visit when the lake was navigable.
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Photo: Kim Vincent. Black Lake June 20, 2017. Just before the last ice melted off the lake.
In addition to the concentration of terrestrially based carbon, the following water chemistry variables were tested to further characterize changes during peak runoff.
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pH
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Chl-a
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TDN
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NH3
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TDP (phosphorus)
Spatial
Correlations
Black Lake + 16 Additional Lakes
Some of the organic matter flushing in from the upland environment flushes right out the outlet without being processed within the lake. But other particles of organic matter sink to the bottom of the lake. In this part of the study, I aim to find taxonomic correlations spatially associated with higher concentrations of terrestrially derived organic matter.
Methods Overview
To see if microbial communities were correlated with areas of higher terrestrially-derived organic matter, we collected water samples in six different locations of Black Lake during the intensive temporal study as well as from the surface and bottom of 15 different lakes throughout the rest of the summer.
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Black Lake Intensive
We collected water samples at four depths within the lake as well as from the inlet and outlet at each visit when the lake was navigable.
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Photo and schematic: Kim Vincent. At each visit, we collected water samples from 6 locations in and near the lake. ​
Surface, inlet, and outlet samples were collected as grab samples. Sub-surface water samples were collected with a Van Dorn.
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What's a Van Dorn, you ask? Click here to see it in action.
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Sixteen Lake Comparison
We collected water samples at the surface and bottom of 16 additional lakes to see if the patterns we might see at Black Lake hold true for other lakes as well.
Snowbank
Frozen
Mills
Thunder
Helene
Odessa
Cony
