Trace Element Transformation during the Development of an Estuarine Algal Bloom

Sanders, James G.; Riedel, Gerhardt F.

doi:10.2307/1352599

Cited by 68 publications

(54 citation statements)

References 38 publications

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“…To what extent is the efficiency of trophic transfer and the biological trapping of toxic substances enhanced by nutrient stimulation of algal production? The speciation and toxicity of some contaminants, such as arsenic and copper (Sanders & Riedel 1993), are also transformed by algal metabolism or excretory products. Does nutrient-enhanced algal production cause change in the overall toxicity of contaminants discharged into coastal waters?…”

Section: A View To the Future: How Can This Science Advance?mentioning

confidence: 99%

Our evolving conceptual model of the coastal eutrophication problem

Cloern¹

2001

Mar. Ecol. Prog. Ser.

2,423

1,533

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A primary focus of coastal science during the past 3 decades has been the question: How does anthropogenic nutrient enrichment cause change in the structure or function of nearshore coastal ecosystems? This theme of environmental science is recent, so our conceptual model of the coastal eutrophication problem continues to change rapidly. In this review, I suggest that the early (Phase I) conceptual model was strongly influenced by limnologists, who began intense study of lake eutrophication by the 1960s. The Phase I model emphasized changing nutrient input as a signal, and responses to that signal as increased phytoplankton biomass and primary production, decomposition of phytoplanktonderived organic matter, and enhanced depletion of oxygen from bottom waters. Coastal research in recent decades has identified key differences in the responses of lakes and coastal-estuarine ecosystems to nutrient enrichment. The contemporary (Phase II) conceptual model reflects those differences and includes explicit recognition of (1) system-specific attributes that act as a filter to modulate the responses to enrichment (leading to large differences among estuarine-coastal systems in their sensitivity to nutrient enrichment); and (2) a complex suite of direct and indirect responses including linked changes in: water transparency, distribution of vascular plants and biomass of macroalgae, sediment biogeochemistry and nutrient cycling, nutrient ratios and their regulation of phytoplankton community composition, frequency of toxic/harmful algal blooms, habitat quality for metazoans, reproduction/growth/survival of pelagic and benthic invertebrates, and subtle changes such as shifts in the seasonality of ecosystem functions. Each aspect of the Phase II model is illustrated here with examples from coastal ecosystems around the world. In the last section of this review I present one vision of the next (Phase III) stage in the evolution of our conceptual model, organized around 5 questions that will guide coastal science in the early 21st century: (1) How do system-specific attributes constrain or amplify the responses of coastal ecosystems to nutrient enrichment? (2) How does nutrient enrichment interact with other stressors (toxic contaminants, fishing harvest, aquaculture, nonindigenous species, habitat loss, climate change, hydrologic manipulations) to change coastal ecosystems? (3) How are responses to multiple stressors linked? (4) How does human-induced change in the coastal zone impact the Earth system as habitat for humanity and other species? (5) How can a deeper scientific understanding of the coastal eutrophication problem be applied to develop tools for building strategies at ecosystem restoration or rehabilitation? Mar Ecol Prog Ser 210: 223-253, 2001 mobilize the nutrient elements nitrogen and phosphorus through land clearing, production and applications of fertilizer, discharge of human waste, animal production, and combustion of fossil fuels (e.g. Nixon 1995). As a result of these activities, surface wat...

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Section: A View To the Future: How Can This Science Advance?mentioning

confidence: 99%

Our evolving conceptual model of the coastal eutrophication problem

Cloern¹

2001

Mar. Ecol. Prog. Ser.

2,423

1,533

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“…Arsenic methylation is slow relative to nutrient cycling, requiring days to convert a majority of the As from inorganic As to organic As even at times of high production and low N : P ratio (Sanders and Windom 1980;Sanders and Riedel 1993). Demethylation is also relatively slow (Sanders 1979;Scudlark and Johnson 1982).…”

Section: Treatment Effects On Dissolved Trace Elementsmentioning

confidence: 99%

The interrelationships among trace element cycling, nutrient loading, and system complexity in estuaries: A mesocosm study

Riedel¹,

Sanders

2003

Estuaries

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Biogeochemical interactions between a suite of trace elements and nutrients were examined in a series of experimental mesocosm experiments to understand how multiple stressors affect estuarine environments and how these effects are modified by the complexity of the system used to examine them. Experimental treatment included additions of nutrients and trace elements separately and combined, along with a gradient in experimental system complexity. Eight mesocosm experiments were carried out from 1996 through 1998. Increased nutrients generally decreased dissolved trace element concentrations, in large part through an increase in phytoplankton biomass, but also by increasing the concentration of metals in the particles. Trace element additions increased dissolved nutrients by decreasing phytoplankton biomass. The presence of sediments reduced both dissolved trace element and nutrient concentrations. Other complexity treatments had weaker effects on both dissolved nutrients and trace elements. Many of the observed effects appeared to be seasonal, occurring only in spring, or their magnitude was greater in spring. This may be linked to a change from phosphorus to nitrogen limitation that often occurs in the Patuxent River estuary in the late spring or early summer period.

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“…In oxic water or sediment, arsenite oxidizes relatively rapidly, with a half-time on the order of days, depending upon temperature, pH, biological activity, and the presence of iron and manganese hydroxides (Johnson and Pilson 1975;Scudlark andJohnson 1982;De Vitre et al 1991). However, many algae can convert arsenate to arsenite (Johnson and Burke 1978;Sanders and Windom 1980;Sanders and Riedel 1993). This may be a process to avoid toxicity from arsenate, which can replace phosphate in many physiological pathways with undesirable results (Planas and Healey 1978;Sanders 1979;Nissen and Benson 1982;Wangberg and Blanck 1990).…”

Section: Introductionmentioning

confidence: 99%

The Annual Cycle of Arsenic in a Temperate Estuary

Riedel

1993

Estuaries

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Dissolved concentrations of four forms of arsenic: arsenite, arsenate, monomethylarsenic, and dimethylarsenic, were measured in the Patuxent River Estuary near Benedict, Maryland, over two annual cycles. In each year, total arsenic concentrations peaked in the summer, in lateJuly and August, while minimum concentrations occurred in winter. Except in late winter, arsenate was a predominant form of arsenic present. In late winter and spring, dimethylarsenic was also a predominant form. A period of monomethylarsenic abundance occurred in summer, following the predominance of dimethylarsenic. Arsenite occurred irregularly in spring. Concurrent temperature and salinity measurements indicate that total arsenic concentrations rose before the summer increase in salinity, suggesting an arsenic source other than the end members, the Patuxent River or Chesapeake Bay.

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Trace Element Transformation during the Development of an Estuarine Algal Bloom

Cited by 68 publications

References 38 publications

Our evolving conceptual model of the coastal eutrophication problem

Our evolving conceptual model of the coastal eutrophication problem

The interrelationships among trace element cycling, nutrient loading, and system complexity in estuaries: A mesocosm study

The Annual Cycle of Arsenic in a Temperate Estuary

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