Journal ArticleDOI
Harmful Algal Blooms and Eutrophication: Nutrient Sources, Composition, and Consequences
TLDR
The relationship between harmful algal blooms and eutrophication of coastal waters from human activities has been investigated in this paper, focusing on sources of nutrients, known effects of nutrient loading and reduction, new understanding of pathways of nutrient acquisition among HAB species, and relationships between nutrients and toxic algae.Abstract:
Although algal blooms, including those considered toxic or harmful, can be natural phenomena, the nature of the global problem of harmful algal blooms (HABs) has expanded both in extent and its public perception over the last several decades. Of concern, especially for resource managers, is the potential relationship between HABs and the accelerated eutrophication of coastal waters from human activities. We address current insights into the relationships between HABs and eutrophication, focusing on sources of nutrients, known effects of nutrient loading and reduction, new understanding of pathways of nutrient acquisition among HAB species, and relationships between nutrients and toxic algae. Through specific, regional, and global examples of these various relationships, we offer both an assessment of the state of understanding, and the uncertainties that require future research efforts. The sources of nutrients poten- tially stimulating algal blooms include sewage, atmospheric deposition, groundwater flow, as well as agricultural and aquaculture runoff and discharge. On a global basis, strong correlations have been demonstrated between total phos- phorus inputs and phytoplankton production in freshwaters, and between total nitrogen input and phytoplankton pro- duction in estuarine and marine waters. There are also numerous examples in geographic regions ranging from the largest and second largest U.S. mainland estuaries (Chesapeake Bay and the Albemarle-Pamlico Estuarine System), to the Inland Sea of Japan, the Black Sea, and Chinese coastal waters, where increases in nutrient loading have been linked with the development of large biomass blooms, leading to anoxia and even toxic or harmful impacts on fisheries re- sources, ecosystems, and human health or recreation. Many of these regions have witnessed reductions in phytoplankton biomass (as chlorophyll a) or HAB incidence when nutrient controls were put in place. Shifts in species composition have often been attributed to changes in nutrient supply ratios, primarily N:P or N:Si. Recently this concept has been extended to include organic forms of nutrients, and an elevation in the ratio of dissolved organic carbon to dissolved organic nitrogen (DOC:DON) has been observed during several recent blooms. The physiological strategies by which different groups of species acquire their nutrients have become better understood, and alternate modes of nutrition such as heterotrophy and mixotrophy are now recognized as common among HAB species. Despite our increased un- derstanding of the pathways by which nutrients are delivered to ecosystems and the pathways by which they are assimilated differentially by different groups of species, the relationships between nutrient delivery and the development of blooms and their potential toxicity or harmfulness remain poorly understood. Many factors such as algal species presence/ abundance, degree of flushing or water exchange, weather conditions, and presence and abundance of grazers contribute to the success of a given species at a given point in time. Similar nutrient loads do not have the same impact in different environments or in the same environment at different points in time. Eutrophication is one of several mechanisms by which harmful algae appear to be increasing in extent and duration in many locations. Although important, it is not the only explanation for blooms or toxic outbreaks. Nutrient enrichment has been strongly linked to stimulation of some harmful species, but for others it has not been an apparent contributing factor. The overall effect of nutrient over- enrichment on harmful algal species is clearly species specific.read more
Citations
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Journal ArticleDOI
Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment.
Julio A. Camargo,Álvaro Alonso +1 more
TL;DR: In this article, a global assessment of the effects of inorganic nitrogen pollution in aquatic ecosystems is presented, with detailed multi-scale data, and three major environmental problems: (1) increasing the concentration of hydrogen ions in freshwater ecosystems without much acid-neutralizing capacity, resulting in acidification of those systems; (2) stimulating or enhancing the development, maintenance and proliferation of primary producers, leading to eutrophication of aquatic ecosystems; (3) reaching toxic levels that impair the ability of aquatic animals to survive, grow and reproduce.
Journal ArticleDOI
The rise of harmful cyanobacteria blooms: The potential roles of eutrophication and climate change
TL;DR: A review of the relationship between eutrophication, climate change and cyanobacterial blooms in freshwater, estuarine, and marine ecosystems can be found in this paper.
Journal ArticleDOI
Eutrophication science: where do we go from here?
Val H. Smith,David W. Schindler +1 more
TL;DR: It will be important to resolve ongoing debates about the optimal design of nutrient loading controls as a water quality management strategy for estuarine and coastal marine ecosystems.
Journal ArticleDOI
Eutrophication and harmful algal blooms: A scientific consensus
J. Heisler,Patricia M. Glibert,JoAnn M. Burkholder,Donald M. Anderson,William P. Cochlan,William C. Dennison,Quay Dortch,Christopher J. Gobler,Cynthia A. Heil,E. Humphries,Alan J. Lewitus,Alan J. Lewitus,Robert E. Magnien,Harold G. Marshall,Kevin G. Sellner,Dean A. Stockwell,Diane K. Stoecker,M. Suddleson +17 more
TL;DR: In January 2003, the US Environmental Protection Agency sponsored a "roundtable discussion" to develop a consensus on the relationship between eutrophication and harmful algal blooms, specifically targeting those relationships for which management actions may be appropriate.
Journal ArticleDOI
Eutrophication of lakes cannot be controlled by reducing nitrogen input: Results of a 37-year whole-ecosystem experiment
David W. Schindler,Robert E. Hecky,David L. Findlay,M. P. Stainton,Brian R. Parker,Michael J. Paterson,Kenneth G. Beaty,M. Lyng,S. E. M. Kasian +8 more
TL;DR: Reducing nitrogen inputs increasingly favored nitrogen-fixing cyanobacteria as a response by the phytoplankton community to extreme seasonal nitrogen limitation, and the lake remained highly eutrophic, despite showing indications of extreme nitrogen limitation seasonally.
References
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Journal ArticleDOI
Human alteration of the global nitrogen cycle: sources and consequences
Peter M. Vitousek,John D. Aber,Robert W. Howarth,Gene E. Likens,Pamela A. Matson,David W. Schindler,William H. Schlesinger,David Tilman +7 more
TL;DR: In this article, a review of available scientific evidence shows that human alterations of the nitrogen cycle have approximately doubled the rate of nitrogen input into the terrestrial nitrogen cycle, with these rates still increasing; increased concentrations of the potent greenhouse gas N 2O globally, and increased concentration of other oxides of nitrogen that drive the formation of photochemical smog over large regions of Earth.
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TL;DR: The state of knowledge regarding the principal considerations in the design of programmes and studies for monitoring water resources and supplies and describes the approaches and procedures used as mentioned in this paper, and the information needed for protecting drinking water sources and recreational water bodies from the health hazards caused by cyanobacteria and their toxins.
Journal ArticleDOI
Agricultural Intensification and Ecosystem Properties
TL;DR: The use of ecologically based management strategies can increase the sustainability of agricultural production while reducing off-site consequences and have serious local, regional, and global environmental consequences.
Journal ArticleDOI
Uptake of new and regenerated forms of nitrogen in primary productivity1
TL;DR: The role of zooplankton in regenerating nitrogen as ammonia in the Sargasso Sea is examined theoretically in this article, showing that only about 10% of the daily ammonia uptake by phytoplanton living in the upper 100 m.
Journal ArticleDOI
Coastal marine eutrophication: A definition, social causes, and future concerns
TL;DR: There is a need in the marine research and management communities for a clear operational definition of the term, eutrophication, and the following are proposed: this definition is consistent with historical usage and emphasizes that eUTrophication is a process, not a trophic state.
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