Coastal waters are increasingly susceptible to low-oxygen conditions where circulation or nutrient inputs have been altered by anthropogenic activities, leading to increased occurrence of coastal hypoxia worldwide. Low-oxygen conditions also occur naturally in coastal settings, typically in bottom water or landward of sills where circulation is weak. Here we identify and characterize a persistent, low-oxygen layer in the mid-w...

Agricultural land use increases the potential for soil erosion when the absence of vegetative cover during the fallow period makes fields vulnerable to runoff. Soil erosion can decrease crop yields and increase sedimentation in downstream water bodies. Agricultural conservation practices, such as the planting of winter cover crops, may protect soils and reduce erosion. To quantify the effect of cover crop use on field- and wat...

Climate change is increasing stream temperatures globally, likely impacting stream ecosystem processes. We conducted a stream warming experiment at the Notre Dame Experimental Mesocosm Facility using N = 24 recirculating mesocosms to examine the effect of warming on biofilm colonization of organic and inorganic substrata and rates of nutrient removal. We conducted an experiment with three temperature treatments (20°C, 23°C, an...

For many Arctic rivers and streams, climate‐driven intensification of permafrost thaw slumping is a major source of disturbance to aquatic habitats. Thaw slumps are dynamic landforms that severely increase total suspended solids (TSS) and nutrients in downstream reaches and can persist over decades. Effects may differ in magnitude as slumps cycle through periods of higher and lower activity, with expansion of retrogressive slu...

Every 17 years, Cicadidae Magicicada emerges in forests across the eastern USA, and their subsequent die-off provides a pulsed subsidy to streams, with unknown impacts on stream ecosystem function. To explore the impact of cicada subsidies on stream ecosystem function, and compare it with leaf litter inputs, we sequentially added dead cicadas and senescent leaf litter to replicated experimental streams. We added dead cicadas a...

Microplastics (particles

High levels of nutrient loads in a catchment indicate the presence of pollution sources that must be identified and quantified. These loads in surface and groundwater have been a major concern that impacts water quality in the Midwestern US, including the Great Lakes Basin. In this study, we use the Soil and Water Assessment Tool (SWAT) to assess the impact of land use changes on hydrology, nutrients, and sediment loads for th...

Watersheds of the coastal temperate rainforests of Pacific North America export large amounts of organic carbon (OC) to the coastal ocean. While it has been suggested that terrestrially derived organic matter could subsidize marine food webs and affect ocean biogeochemistry along the coastal margin, little work has been done to quantify and characterize OC across the freshwater to marine continuum. We conducted monthly and tar...

Studies of trophic‐level material and energy transfers are central to ecology. The use of isotopic tracers has now made it possible to measure trophic transfer efficiencies of important nutrients and to better understand how these materials move through food webs. We analyzed data from thirteen 15 N‐ammonium tracer addition experiments to quantify N transfer from basal resources to animals in headwater streams with varying phy...

We present a comprehensive data set of gross primary production (GPP) and ecosystem respiration (ER) in open‐canopy, nutrient‐rich streams draining row‐crop agriculture in the midwestern United States. We used two approaches to characterize temporal and spatial variation in whole‐stream metabolism: continuous measurements in one agricultural stream for 1 yr, and periodic daily measurements in six agricultural streams on six da...

Most nitrogen (N) assimilation in lake and marine ecosystems is often subsequently released via autochthonous dissolved organic nitrogen (DON) production, but autochthonous DON production has yet to be quantified in flowing waters. We measured in‐stream DON production following 24 h 15 N‐nitrate () tracer additions in 36 headwater streams, a subset of sites from the second Lotic Intersite Nitrogen eXperiment. Streams were loca...