We are investigating the feasibility of employing thermal manipulation, achieved via whole-lake destratification, to extirpate the cold water exotic rainbow smelt (Osmerus mordax) from Crystal Lake, WI. We focus here on the engineering implications of raising the hypolimnion water temperture to exceed the thermal range of the rainbow smelt. An energy balance approach was used to determine the timing and duration of mixing efforts to maximize heat gain and minimize loss to the atmosphere.

We examined benthic microbial communities in three contrasting subtidal salt marsh sediments over the course of a year to investigate the relationship between environmental conditions and benthic microbial community structure. Samples were collected monthly from a high energy, sandy beach, a tidal creek bed, and a Spartina alterniflora marsh border. The concentrations and biomasses of benthic microalgae (BMA), total and potentially active bacteria (measured by an enzyme-activated fluorogenic compound), heterotrophic protists, and metazoan meiofauna were measured at each location.

Background/Questions/Methods

Plant diversity has been studied extensively for its impact on a few basic measures, such as biomass production. However, relatively little is understood about interactions between plant diversity and microbial communities. Through removal of natural enemies with pesticide treatments, we found that foliar fungi have a significant impact on plant productivity, and that the impact is greater at higher than at lower plant diversity.

Drought-related tree mortality occurs worldwide, including recent episodes in piñon-juniper woodlands of the American west. Although the physiological mechanisms of mortality are poorly understood, carbon starvation may occur in trees that limit transpiration (E) to avoid hydraulic failure.

 Biogeochemical fluxes through urban residences contribute significantly to the overall biogeochemical cycles of cities and of the nation. However, little is known about how biogeochemical fluxes that contribute to environmental pollution vary among households, nor what factors contribute to that variation. We quantified the fluxes of carbon (C), nitrogen (N), and phosphorus (P) through households along an urban to exurban gradient in the Saint Paul-Minneapolis, Minnesota metropolitan area.

The dominant theme of socio-ecological research in the Luquillo LTER Research Program is the influence of land use change on local climate change, secondary forest dynamics, watershed and stream processes, and ecosystem services. Much of our research is being developed in the context of the steep urban to wildlands gradient from the Rio Piedras watershed (RPW) in the center of San Juan metropolitan area(SJMA) to the Luquillo Experimental Forest (LEF) some 25 km away.

Arctic warming has been linked to changes in carbon cycling in this region. Cold temperatures and anoxic conditions in the Arctic inhibit microbial activity, lowering decomposition rates. As a result mineralization rates are low, resulting in nitrogen-limited-system, further reducing biological activity. Evidence has shown that eliminating this constraint on nutrient availability results in a vegetation shift and loss of soil carbon; however, the mechanisms behind soil carbon loss are not understood.

Dissolved organic matter (DOM) dominates the material and energy fluxes within aquatic ecosystems. Carbon fuels the majority of microbial processes, including those that regulate in-stream nitrogen constituents. DOM sources and in situ transformations determine its chemical nature and lability within aquatic systems. Boulder Creek, which is located in the Colorado Front Range and spans an ecosystem gradient from the Continental Divide to the high plains, receives excess atmospheric nitrogen deposition due to its proximity to population centers and agricultural lands.

Ecosystems in topographically complex (mountainous) terrain are responsible for a majority of land-atmosphere CO2 exchange (net ecosystem exchange; NEE) across the western United States due to high inputs of winter precipitation as snowfall. NEE in these regions has been historically difficult to quantify using the eddy covariance (EC) method, however, due to complexities in surface terrain that lead to irregularities in streamline air flow, particularly advective fluxes during periods of low turbulent mixing.