John A. Downing

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Because freshwater covers such a small fraction of the Earth’s surface area, inland freshwater ecosystems (particularly lakes, rivers, and reservoirs) have rarely been considered as potentially important quantitative components of the carbon cycle at either global or regional scales. By taking published estimates of gas exchange, sediment accumulation, and(More)
A controversial precept of aquatic ecology asserts that low ratios of nitrogen to phosphorus (N:P) lead to noxious and sometimes toxic blooms of Cyanobacteria. Cyanobacteria dominance is a major risk to human and ecosystem health. The stoichiometric control of Cyanobacteria therefore has become central to freshwater resource management. This controversial(More)
One of the major impediments to the integration of lentic ecosystems into global environmental analyses has been fragmentary data on the extent and size distribution of lakes, ponds, and impoundments. We use new data sources, enhanced spatial resolution, and new analytical approaches to provide new estimates of the global abundance of surface-water bodies.(More)
Inland waters (lakes, reservoirs, streams, and rivers) are often substantial methane (CH(4)) sources in the terrestrial landscape. They are, however, not yet well integrated in global greenhouse gas (GHG) budgets. Data from 474 freshwater ecosystems and the most recent global water area estimates indicate that freshwaters emit at least 103 teragrams of(More)
P early mussels (Unionacea) are among the most fascinating, most widespread, and most endangered animals in fresh waters. They play important roles in freshwater ecosystems and are economically valuable for their shells and pearls. Recent research, fueled by concern over widespread extinctions and population declines, has produced valuable and even(More)
We describe the relationships between summer average total phosphorus (TP) and the biomass of six major phytoplankton taxonomic groups from 91 north temperate lakes. Both regression and a locally weighted smoothing (LOWESS) analyses show that all groups increase with TP but over different nutrient ranges. At nutrient extremes, i.e. very low and high levels(More)
[1] We estimated organic carbon (OC) burial over the past century in 40 impoundments in one of the most intensively agricultural regions of the world. The volume of sediment deposited per unit time varied as a function of lake and watershed size, but smaller impoundments had greater deposition and accumulation rates per unit area. Annual water storage(More)
During May-September 2000-2001, physicochemical data were collected from 241 lakes in Missouri, Iowa, northeastern Kansas, and southern Minnesota U.S.A., to determine the environmental variables associated with high concentrations of the cyanobacterial hepatotoxin microcystin (MC). The study region represents a south-north latitudinal gradient in increasing(More)
We quantified macroinvertebrate community characteristics in nine temporary or permanent wetlands, and related these to environmental conditions. Macroinvertebrates inhabiting the water column and shallow sediment (42-cm depth) were sampled 20 months after wetland construction in June 2005. A total of 29 taxa were collected, and macroinvertebrate(More)