Runoff of agricultural nutrients and sediments has led to re-eutrophication of lakes and impaired stream health in the Great Lakes Basin since around 2000 following earlier success in protecting water quality. Substantial investment in conservation actions has had insufficient impact, due in part to a limited basis for understanding the likely environmental outcomes of those investments. This article introduces a special section focusing on promoting investment that produces environmental outcomes as opposed to investing in conservation actions with unknown effects.

Quantifying rates of primary production and respiration is fundamental to understanding ecosystem function. This study utilized high-frequency time series, buoy-based sensor data to estimate daily primary production and respiration rates during the summers of 2012–2015 in southern Green Bay, Lake Michigan. Highly coherent diel oscillations of dissolved oxygen concentrations in epilimnetic waters were commonly observed for much of the summer via 30-min time intervals from the GLOS buoy (NOAA 45014) sensor array.

Lake Ontario's condition has fluctuated since European settlement, and our understanding of the linkages between observed ecosystem shifts and stressors is improving. Changes in the physical and chemical environment of the lake due to non-indigenous species, pollution, sedimentation, turbidity, and climate change altered the pelagic primary producers, so algal assessments have been valuable for tracking long-term conditions. We present a chronological account of algal assessments to summarize past and present environmental conditions in Lake Ontario.

Pollution by plastic debris is an increasing environmental concern in the Laurentian Great Lakes where it affects open-water, shoreline, and benthic environments. Open-water surveys reveal that, in certain areas of the Great Lakes, surface water densities of plastics are as high as those reported for areas of litter accumulation within oceanic gyres. Data from volunteer beach cleanups show that typically more than 80% of anthropogenic litter along the shorelines of the Great Lakes is comprised of plastics.

Pollution by plastic debris is an increasing environmental concern in the Laurentian Great Lakes where it affects open-water, shoreline, and benthic environments. Open-water surveys reveal that, in certain areas of the Great Lakes, surface water densities of plastics are as high as those reported for areas of litter accumulation within oceanic gyres. Data from volunteer beach cleanups show that typically more than 80% of anthropogenic litter along the shorelines of the Great Lakes is comprised of plastics.