NWT scientists are investigating how global changes like climate warming, nitrogen deposition, and the introduction of invasive species are altering food web dynamics within high elevation lake ecosystems. In alpine lakes, an extended summer season resulting from warmer climatic conditions will likely shift the limitation of phytoplankton production from flushing and UV stress to nutrient limitation and zooplankton grazing. The effect of solar ultraviolet radiation, which increases in intensity with elevation, can be modified by both temperature and DOM concentrations. Changes in climate (earlier ice-off, warming) reduce summer stream flow into Green Lake 4 in the Green Lakes Valley, while also increasing stratification and water temperatures, and raising late-season solute concentrations (including nitrate;Miller and McKnight 2012). These changes increase the amount of resources (N, P, silica) available to phytoplankton, increasing chlorophyll a levels and autochthonously-produced organic material that can help protect against UV damage. Daphnia populations also increase, likely resulting in greater phytoplankton herbivory. Dissolved organic matter inputs help attenuate the harmful effects of UV radiation and provide an added source of carbon that can fuel food-web dynamics. Lower in elevation, interannual changes in flushing rate are more buffered and solute transport from forested areas relax resource limitation across most climate conditions.
Investigators: Pieter Johnson, Diane McKnight
Rocky Mountain Lake Algae is a collaborative effort by Niwot Ridge LTER and Rocky Mountain Nat'l Park just North and west of Boulder Colorado. This site is part of an ongoing larger effort to study the ecology and biogeochemistry of Rocky Mountain Lakes. Website hosted a sister server was development was supported by the Niwot Ridge Long-Term Ecological Research Site and the National Science Foundation.
This site is an online database for ecolgical studies. Algae are a very large, diverse group of organisms that photosynthesize. few of the algae are closely related to one another and they belong to separate taxonomic groups. Rather than being members of the same evolutionary lineage, the algae share little history in common. Please click the link below.
Project Leader: Dr. Diane McKnight
This material is based upon work supported by the National Science Foundation under Cooperative Agreement #DEB-1027341. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necesarily reflect the views of the National Science Foundation.
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