Received: 18 April 2019 Revised: 22 June 2019 Accepted: 2 July 2019 DOI: 10.1002/wat2.1373 OVERVIEW Nutrients, eutrophication and harmful algal blooms along the freshwater to marine continuum Wayne A. Wurtsbaugh1 | Hans W. Paerl2 | Walter K. Dodds3 1Watershed Sciences Department, Utah State University, Logan, Utah Abstract 2Institute of Marine Sciences, University of Agricultural, urban and industrial activities have dramatically increased aquatic North Carolina at Chapel Hill, Morehead nitrogen and phosphorus pollution (eutrophication), threatening water quality and City, North Carolina biotic integrity from headwater streams to coastal areas world-wide. Eutrophication 3Division of Biology, Kansas State creates multiple problems, including hypoxic “dead zones” that reduce fish and University, Manhattan, Kansas shellfish production; harmful algal blooms that create taste and odor problems and Correspondence threaten the safety of drinking water and aquatic food supplies; stimulation of Wayne A. Wurtsbaugh, Watershed Sciences Department, Utah State University, Logan, greenhouse gas releases; and degradation of cultural and social values of these Utah 94322-5210. waters. Conservative estimates of annual costs of eutrophication have indicated $1 Email:
[email protected] billion losses for European coastal waters and $2.4 billion for lakes and streams in Funding information the United States. Scientists have debated whether phosphorus, nitrogen, or both NSF Konza LTER, Grant/Award Numbers: need to be reduced to control eutrophication along the freshwater to marine contin- NSF OIA-1656006, NSF DEB 1065255; uum, but many management agencies worldwide are increasingly opting for dual Dimensions of Biodiversity, Grant/Award Numbers: 1831096, 1240851; US National control. The unidirectional flow of water and nutrients through streams, rivers, Science Foundation, Grant/Award Numbers: lakes, estuaries and ultimately coastal oceans adds additional complexity, as each CBET 1230543, 1840715, OCE 9905723, of these ecosystems may be limited by different factors.