scholarly journals Outsized nutrient contributions from small tributaries to a Great Lake

2020 ◽  
Vol 117 (45) ◽  
pp. 28175-28182
Author(s):  
Robert J. Mooney ◽  
Emily H. Stanley ◽  
William C. Rosenthal ◽  
Peter C. Esselman ◽  
Anthony D. Kendall ◽  
...  
Keyword(s):  
Algal Blooms ◽  
Lake Michigan ◽  
Nutrient Loading ◽  
The United States ◽  
Ecological Impacts ◽  
Water Bodies ◽  
Nutrient Loads ◽  
Nutrient Inputs ◽  
Small Streams ◽  
Large Water

Excessive nitrogen (N) and phosphorus (P) loading is one of the greatest threats to aquatic ecosystems in the Anthropocene, causing eutrophication of rivers, lakes, and marine coastlines worldwide. For lakes across the United States, eutrophication is driven largely by nonpoint nutrient sources from tributaries that drain surrounding watersheds. Decades of monitoring and regulatory efforts have paid little attention to small tributaries of large water bodies, despite their ubiquity and potential local importance. We used a snapshot of nutrient inputs from nearly all tributaries of Lake Michigan—the world’s fifth largest freshwater lake by volume—to determine how land cover and dams alter nutrient inputs across watershed sizes. Loads, concentrations, stoichiometry (N:P), and bioavailability (percentage dissolved inorganic nutrients) varied by orders of magnitude among tributaries, creating a mosaic of coastal nutrient inputs. The 6 largest of 235 tributaries accounted for ∼70% of the daily N and P delivered to Lake Michigan. However, small tributaries exhibited nutrient loads that were high for their size and biased toward dissolved inorganic forms. Higher bioavailability of nutrients from small watersheds suggests greater potential to fuel algal blooms in coastal areas, especially given the likelihood that their plumes become trapped and then overlap in the nearshore zone. Our findings reveal an underappreciated role that small streams may play in driving coastal eutrophication in large water bodies. Although they represent only a modest proportion of lake-wide loads, expanding nutrient management efforts to address smaller watersheds could reduce the ecological impacts of nutrient loading on valuable nearshore ecosystems.

Prediction of harmful algal blooms in large water bodies using the combined EFDC and LSTM models

2021 ◽  
Vol 295 ◽  
pp. 113060
Author(s):  
Lei Zheng ◽  
Huipeng Wang ◽  
Cao Liu ◽  
Shurong Zhang ◽  
Aizhong Ding ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Water Bodies ◽  
Large Water

Water quality impacts from tidal flooding in the northeast coast of the U.S.

2020 ◽  
Author(s):  
Alfonso Macias-Tapia ◽  
Margaret Mulholland ◽  
Derek Loftis ◽  
Corday Selden ◽  
Peter Bernhardt
Keyword(s):  
Sea Level ◽  
Inorganic Nitrogen ◽  
Biological Effects ◽  
The United States ◽  
Coastal Flooding ◽  
Nitrogen Loading ◽  
Water Bodies ◽  
Nutrient Inputs ◽  
Tidal Flooding ◽  
Northeast Coast

<p>Little is known about the chemical and biological effects of tidal flooding on adjacent aquatic environments. Terrestrial systems accumulate various types of organic and inorganic matter that can be dissolved or carried into adjacent water bodies as floodwaters recede. In the northeast coast of the United States, the incidence and duration of coastal flooding has increased due to the high relative rates of sea level rise in the region.  Much of this flooding is tidal, occurring in the absence of rainfall during spring tides and/or when wind-induced Ekman transport is onshore.  While there are estimates of stormwater inputs into coastal systems, material (e.g., sediment, nutrients and contaminating bacteria) transported into the water bodies as tidal floodwaters recede have not been measured. Here, we will report estimates of nutrient loads transported in receding floodwaters during tidal flooding associated with perigean spring tides in 2017, 2018, and 2019. During each of the three years, at the highest point of the tide trained, citizen scientists were deployed to areas known to routinely flood in the Lafayette River watershed, a sub-tributary of the lower Chesapeake Bay, located in Norfolk, Virginia (USA). More than 100 samples were collected during each year as the flood waters retreated. Particulate carbon and nitrogen, total dissolved nitrogen, ammonium, nitrite, nitrate, urea, and phosphate were analyzed using standard colorimetric methods. Additionally, samples were analyzed for Enterococcus abundance each year. Results suggest that dissolved inorganic nitrogen loading during a single tidal flooding event exceeds the total annual load allocated for runoff in this sub-estuary.  Because tidal flooding is projected to increase in the future as sea level continues to rise, further research should proceed to better constraint the amounts and characteristics of loadings associated to tidal flooding events. Furthermore, these results suggest that managers should consider nutrient inputs via coastal flooding when setting restoration goals and targets.</p>

scholarly journals Role of external inputs of nutrients to aquatic ecosystems in determining prevalence of nitrogen vs. phosphorus limitation of net primary productivity

2021 ◽  
Author(s):  
R. W. Howarth ◽  
F. Chan ◽  
D. P. Swaney ◽  
R. M. Marino ◽  
M. Hayn
Keyword(s):  
Primary Productivity ◽  
Nutrient Loading ◽  
Net Primary Productivity ◽  
N:P Ratio ◽  
The United States ◽  
Marine Ecosystems ◽  
Nutrient Inputs ◽  
Redfield Ratio ◽  
Coastal Marine ◽  
Coastal Marine Ecosystems

AbstractWhether net primary productivity in an aquatic ecosystem is limited by nitrogen (N), limited by phosphorus (P), or co-limited by N & P is determined by the relative supply of N and P to phytoplankton compared to their elemental requirements for primary production, often characterized by the “Redfield” ratio. The supply of these essential nutrients is affected by both external inputs and biogeochemical processes within the ecosystem. In this paper, we examine external sources of nutrients to aquatic systems and how the balance of N to P inputs influences nutrient limitation. For ocean subtropical gyres, a relatively balanced input of N and P relative to the Redfield ratio from deep ocean sources often leads to near co-limitation by N and P. For lakes, the external nutrient inputs come largely from watershed sources, and we demonstrate that on average the N:P ratio for these inputs across the United States is well above that needed by phytoplankton, which may contribute to P limitation in those lake that experience this average nutrient loading. Watershed inputs are also important for estuaries and coastal marine ecosystems, but ocean sources of nutrients are also significant contributors to overall nutrient loads. The ocean-nutrient sources of N and P are very often at or below the Redfield ratio of 16:1 molar, and can be substantially so, particularly in areas where the continental shelf is wide. This large input of coastal ocean nutrients with a low N:P ratio is one factor that may make N limitation more likely in many coastal marine ecosystems than in lakes.

scholarly journals From heterotrophy to autotrophy: a freshwater estuarine ecosystem recovering from hypereutrophication

2009 ◽  
Vol 6 (3) ◽  
pp. 5431-5459 ◽  
Author(s):  
T. J. S. Cox ◽  
T. Maris ◽  
K. Soetaert ◽  
D. J. Conley ◽  
S. Van Damme ◽  
...  
Keyword(s):  
Algal Blooms ◽  
Alternative Stable States ◽  
Algal Growth ◽  
Nutrient Loads ◽  
Nutrient Inputs ◽  
Stable States ◽  
Estuarine Ecosystem ◽  
High Ammonia ◽  
Estuarine Systems ◽  
Algal Growth Inhibition

Abstract. Increased organic matter and nutrient loads have induced major changes in aquatic systems, including hypoxia and algal blooms. In enclosed ecosystems these changes were often not gradual due to non-linear mechanisms. Here we report a 40 year record of eutrophication and hypoxia on an estuarine ecosystem and its recovery from hypereutrophication. We observe a paradoxical increase in chlorophyll a concentrations with decreasing nutrient inputs, and we hypothesise that algal growth was inhibited due to hypereutrophication, either by elevated ammonium concentrations, severe hypoxia or the production of harmful substances in such a reduced environment. We study the dynamics of a simple but realistic mathematical model, incorporating the assumption of algal growth inhibition. It shows an autotrophic equilibrium with low ammonia inputs, and a heterotrophic equilibrium with high ammonia inputs. At intermediate ammonia inputs it displays two alternative stable states. We conclude that the recovery of hypereutrophic riverine/estuarine systems can exhibit threshold-like behaviour.

scholarly journals Long-term influence of climate and experimental eutrophication regimes on phytoplankton blooms

2019 ◽  
Author(s):  
Kateri R. Salk ◽  
Jason J. Venkiteswaran ◽  
Raoul-Marie Couture ◽  
Scott N. Higgins ◽  
Michael J. Paterson ◽  
...  
Keyword(s):  
Climate Change ◽  
Algal Blooms ◽  
Nutrient Loading ◽  
Data Availability ◽  
Change Scenario ◽  
Nutrient Loads ◽  
Phytoplankton Blooms ◽  
Experimental Lakes Area ◽  
Link Type

AbstractPhytoplankton blooms respond to multiple drivers, including climate change and nutrient loading. Here we examine a long-term dataset from Lake 227, a site exposed to a fertilization experiment (1969–present). Changes in nitrogen:phosphorus loading ratios (high N:P, low N:P, P-only) did not impact mean annual biomass, but blooms exhibited substantial inter- and intra-annual variability. We used a process-oriented lake model, MyLake, to successfully reproduce lake physics over 48 years and test if a P-limited model structure predicted blooms. The timing and magnitude of blooms was reproduced during the P-only period but not for the high and low N:P periods, perhaps due to N acquisition pathways not currently included in the model. A model scenario with no experimental fertilization confirmed P loading is the major driver of blooms, while a scenario that removed climate-driven temperature trends showed that increased spring temperatures have exacerbated blooms beyond the effects of fertilization alone.Significance StatementHarmful algal blooms and eutrophication are key water quality issues worldwide. Managing algal blooms is often difficult because multiple drivers, such as climate change and nutrient loading, act concurrently and potentially synergistically. Long-term datasets and simulation models allow us to parse the effects of interacting drivers of blooms. The performance of our model depended on the ratio of nitrogen to phosphorus inputs, suggesting that complex biological dynamics control blooms under variable nutrient loads. We found that blooms were dampened under a “no climate change” scenario, suggesting that the interaction of nutrient loading and increased temperature intensifies blooms. Our results highlight successes and gaps in our ability to model blooms, helping to establish future management recommendations.Data Availability StatementData and metadata will be made available in a GitHub repository (https://github.com/biogeochemistry/Lake-227). Upon manuscript acceptance, the repository will be made publicly available and a DOI will be provided. We request that data users contact the Experimental Lakes Area directly, per their data use policy (http://www.iisd.org/ela/wp-content/uploads/2016/04/Data-Terms-And-Conditions.pdf).

scholarly journals Legacy Phosphorus in Lake Okeechobee (Florida, USA) Sediments: A Review and New Perspective

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 39
Author(s):  
Thomas M. Missimer ◽  
Serge Thomas ◽  
Barry H. Rosen
Keyword(s):  
Algal Blooms ◽  
Nutrient Loading ◽  
Sediment Resuspension ◽  
Eutrophic Lake ◽  
The United States ◽  
Nutrient Ratios ◽  
Lake Okeechobee ◽  
Organic Sediment ◽  
Legacy Nutrients ◽  
New Perspective

Lake Okeechobee is one of the largest freshwater lakes in the United States. As a eutrophic lake, it has frequent algal blooms composed predominantly of the cyanobacterium genus Microcystis. Many of the algal blooms are associated with the resuspension of a thixotropic benthic mud containing legacy nutrients. Since Lake Okeechobee has an area of 1732 km2 (40–50 km radius) and a mean depth of only 2.7 m, there is sufficient fetch and shallow water depth to allow frequent wind, wave, and current generated events, which cause sediment resuspension. Three types of mud exist in the lake including an immobile dark-colored, consolidated mud, a brownish-colored mud, which is poorly consolidated and mobile, and a dark-colored thixotropic, highly mobile mud that is a mixture of organic matter and clay-sized minerals. Altogether, these muds contain an estimated 4.6 × 106 kg of total phosphorus and commensurate high amounts of labile nitrogen. The thixotropic mud covers most of the lakebed and contains the suitable nutrient ratios to trigger algal blooms. A bioassay analysis of the thixotropic mud compared to the consolidated mud showed that it produced up to 50% more nutrient mass compared to the consolidated mud. The thixotropic mud does not consolidate, thus remains mobile. The mobility is maintained by the dynamics of the algal blooms and bacterial decay of extracellular secretions (transparent exopolymer particles) that bind sediment, transfer it to the bottom, and undergo bacterial digestion causing gas emissions, thus maintaining the organic/sediment matrix in suspension. Despite major efforts to control external nutrient loading into the lake, the high frequency of algal blooms will continue until the muds bearing legacy nutrients are removed from the lake.

Risk of infestation of population by opisthorchiasis causative agent in the middle and lower current of the Iset river. influence of loimopotential of the focus of infestation on the risk values

2017 ◽  
pp. 52-56
Author(s):  
A.V. Ushakov ◽  
R.G. Fattakhov ◽  
T.F. Stepanova
Keyword(s):  
Causative Agent ◽  
Water Bodies ◽  
Risk Of Infection ◽  
Natural Focus ◽  
Opisthorchis Felineus ◽  
Large Water

The risk of infestation of the population by the opisthorchiasis causative agent in the middle and lower reaches of the Iset River was estimated. Areas with the highest risk of peoples infection by Opisthorchis felineus’ metacercaria are identified. These territories are confined to the zones of removal of the opisthorchiasis causative agent, which are river beds and large water bodies that constantly connect with rivers. Steady risk of infection of the population is determined by the loimopotential of the opisthorchiasis natural focus. The general infestation of juveniles fishes in the middle and lower current of the Iset River made 9,9 %, annuals – 21,5 %, two-year-olds – 19,5 %.

Water Quality Trends in Hamilton Harbour: 1987 to 1995

1996 ◽  
Vol 31 (3) ◽  
pp. 473-484 ◽  
Author(s):  
Murray N. Charlton ◽  
Robin Le Sage
Keyword(s):  
Algal Blooms ◽  
Action Plan ◽  
Secchi Depth ◽  
Water Clarity ◽  
Nutrient Loads ◽  
Hamilton Harbour ◽  
Near Shore ◽  
The Media ◽  
Park Area ◽  
Water Quality Trends

Abstract A series of water samples and Secchi depth measurements were conducted in Hamilton Harbour between 1987 and 1995. The data indicate little recent improvement in the harbour generally. Detection of real improvements may require high frequency sampling and a more extensive sample grid once a cause for improvement is in place. Some measures, such as chlorophyll and Secchi depth, approach RAP initial goals sometimes during recent years, but algal blooms still occur, which prevent attainment of satisfactory average conditions. The cause of aesthetic improvements in water clarity reported in the media was investigated with sampling along an inshore-offshore transect and intense Secchi measurements in the LaSalle Park area. The data are consistent with a transient clarifying effect of zebra mussels on structures near shore. The need to reduce nutrient loads as recommended in the Remedial Action Plan continues.

scholarly journals Marine harmful algal blooms (HABs) in the United States: History, current status and future trends

Harmful Algae ◽  
2021 ◽  
pp. 101975
Author(s):  
Donald M. Anderson ◽  
Elizabeth Fensin ◽  
Christopher J. Gobler ◽  
Alicia E. Hoeglund ◽  
Katherine A. Hubbard ◽  
...  
Keyword(s):  
United States ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
United States History ◽  
The United States ◽  
Current Status ◽  
Future Trends ◽  
States History

scholarly journals Agricultural Conservation Practices and Aquatic Ecological Responses

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1687
Author(s):  
Richard E. Lizotte ◽  
Peter C. Smiley ◽  
Robert B. Gillespie ◽  
Scott S. Knight
Keyword(s):  
Aquatic Ecosystems ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Soil Health ◽  
Conservation Agriculture ◽  
Agricultural Runoff ◽  
The United States ◽  
Ecosystem Structure ◽  
Ecological Responses ◽  
And Function

Conservation agriculture practices (CAs) have been internationally promoted and used for decades to enhance soil health and mitigate soil loss. An additional benefit of CAs has been mitigation of agricultural runoff impacts on aquatic ecosystems. Countries across the globe have agricultural agencies that provide programs for farmers to implement a variety of CAs. Increasingly there is a need to demonstrate that CAs can provide ecological improvements in aquatic ecosystems. Growing global concerns of lost habitat, biodiversity, and ecosystem services, increased eutrophication and associated harmful algal blooms are expected to intensify with increasing global populations and changing climate. We conducted a literature review identifying 88 studies linking CAs to aquatic ecological responses since 2000. Most studies were conducted in North America (78%), primarily the United States (73%), within the framework of the USDA Conservation Effects Assessment Project. Identified studies most frequently documented macroinvertebrate (31%), fish (28%), and algal (20%) responses to riparian (29%), wetland (18%), or combinations (32%) of CAs and/or responses to eutrophication (27%) and pesticide contamination (23%). Notable research gaps include better understanding of biogeochemistry with CAs, quantitative links between varying CAs and ecological responses, and linkages of CAs with aquatic ecosystem structure and function.

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