Links to papers related to her topic can be downloaded using the following links:
Thursday, March 19, 2015
Dr. Mosher's Seminar
This Friday, we are hosting Dr. Jennifer Mosher as our invited seminar speaker. Dr. Mosher is a former YSU graduate student who earned her M.S. under the tutelage of Dr. Carl Johnston. I strongly urge that you engage with Dr. Mosher while she is here. Below is the flyer of her seminar.
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Dr. Mosher has prepared the following abstract for her presentation tomorrow:
ReplyDeleteMicrobes drive ecosystem processes, but the River Continuum Concept (RCC) is silent about microbes other than heterotrophic use of organic compounds. Nevertheless, the basic tenet of the RCC, i.e. communities adjust to patterns of organic loading and downstream communities capitalize on upstream processing inefficiencies, should hold true for microbial communities. We analyzed stream water DOM composition with ultra-high resolution mass spectrometry and high throughput pyrosequencing of bacterial 16S rRNA amplicons to characterize benthic microbial communities of first- through fifth-order streams from forested catchments: Neversink River, Catskill Mountains; White Clay Creek, Pennsylvania Piedmont; Rio Tempisquito, Cordillera de Guanacaste. Bacterial richness followed patterns of dissolved organic matter (DOM) molecular richness observed at the catchment scale while catchments exhibited synchronous declines in microbial and DOM richness with increasing stream order. Between 20% to 30% of bacterial genera were cosmopolitan, and major differences among communities were observed mostly at the catchment level, followed by habitat (riffle or run), and then stream order. The presence of algae influenced bacterial community structure. Our data, while different from the RCC prediction, are consistent with an intimate connectivity of first-order stream chemistry and terrestrial sources and exceptionally short uptake lengths in shallow, slower moving first-order streams.
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ReplyDeleteDr. Mosher's presentation focused on her research in microbial stream ecology in relation to the River Continuum Concept (RCC). Analyzing dissolved organic matter (DOM) composition across watersheds with different stream orders and habitats found that microbial richness influenced bacterial community structure. A longitudinal shift was seen when comparing the experimental bacterial curve compared to the RCC. This increase in diversity in first order streams proves the RCC to be limited in applicability to imperfect river models.
ReplyDeleteWhat impacts (human or environmental) on river systems can affect the widely accepted RCC?
One way that the RCC could be affected is by contamination by humans. This could be seen within our own backyard. The Mahoning River is considered to be one of the top 5 polluted rivers within the United States. This is largely due to the Steel Industry and the release of partially treated human waste over many decades as the city was growing. It has been found that within the sediments that line the river, there are high levels of polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls, and numerous heavy metals. Studies have been conducted upon microbial activity and how pollutants present within the river affect this. In some of these preliminary studies, the activity levels of some bacteria’s ability to degrade PAH were higher within highly contaminated areas versus lower. Further studies are needed to determine how these pollutants affect these bacterial on a genetic level.
ReplyDeleteAcid rain would have an affect on the RCC by negatively impacting the aquatic environment. Acid rain causes a decrease in the pH of the water making it overall too acidic for most of the naturally occurring habitat. When the water and the soil are incapable of neutralizing the acidic compounds from the acid rain then the aquatic environment is severely jeopardized. The acid rain begins to release aluminum into the surrounding environment which is toxic to aquatic species and organisms. Aluminum toxicity can affect the biodiversity of many microbial communities as well as completely degrade or denature them.
ReplyDeleteI am not too familiar with this area of biology but i believe human activities such as the dumping of sewages in water bodies affect the widely accepted RCC. Sewage dumping in water bodies like streams could lead to eutrophication of such streams. This would result in an explosive growth of algae and phytoplanktons leading to higher oxygen demand by this organisms. Excessive uptake of oxygen can result in a hypoxic condition of that stream. In this condition, strict aerobes might not be able to thrive and this might result in the depletion of the microbial diversity of the water body.
ReplyDeleteSewage runoff, especially during large snow melts and storms, can cause over-burdened water treatment systems. This will essentially result in partially or completely untreated water to flow into rivers and streams. This can lead to shifts in microbial diversity and a shift in the resources that bacteria rely on. This would most likely have an effect on the RCC.
ReplyDeleteDr. Mosher’s presentation was an interesting look into the world of stream ecology with regards to bacterial activity. The concept of a river’s size/order having such a significant effect on the bacterial community and its actions has a much greater depth that I could have realized.
ReplyDeleteAgricultural run-off, such as pesticides and fertilizers, and other ground-water pollution sources could have a significant effect on the RCC if they come into contact with river systems/streams. This type of effect could also increase in magnitude as stream order increases due to the additive effect of several potentially contaminated sources joining together.
The human influences along the banks will also have an effect. Trees and smaller plants with a lot of deep roots are going to hold sediment in place and prevent the bank from collapsing into the water. They also may serve as a filter to containments before runoff water enters the stream. If these trees are removed, sediments and pollutants could enter the water and change the quality. Roadways along waterways will also have an impact. Beyond the initial impacts of clearing a path for the road, salt runoff and trash thrown from vehicles will affect nearby water. Further back from the bank itself, all riparian land use will have an effect on the river through groundwater and runoff. Whether there is a factory or farm close to a river will impact the ecology of the river itself.
ReplyDeleteWithout being present for the talk, I would assume that 1st order streams don't fit into this concept due to their smaller size and thus increased susceptibility to variables like pollution, contamination, etc, all of which can be (and are) caused by humans.
ReplyDeleteAnother form of human impact can come from acid mine drainage, which refers to the outflow of acidic water from metal mines or coal mines. This run off can cause contamination of river water raising the pH as well as elevating toxic trace metals into the environment. HOwever, the use of various microorganisms that can thrive under these acidic conditions. It is even suggested of using certain bacteria for the purpose of bioremedation.
ReplyDeleteShift in micro-organims communities would affect the RCC. Different micro-organisms require different nutrients. If there is a drastic increase or decrease in one population, nutrient and even mineral availability will shift. For example if agricultural run-off caused an algal bloom in the first order stream, toxins would now be part of the element composition and would affect other microbial communities. The subsequent second order stream would be affected as a result, and so forth.
ReplyDeleteI am very pleased with all the above comments. They have been very thoughtful. Thanks for your response to Gabriella's question. I truly hope all of you enjoyed our guest's presentation.
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